JP2505264B2 - Method for manufacturing optical information recording medium - Google Patents

Description

The present invention relates to a method for manufacturing an optical information recording medium such as an optical disc, and more particularly to a method for manufacturing an optical information recording medium using the 2P method. .

[Prior Art] One of the optical disk recording methods is a CAV (Constant Angular Velocity) method in which the angular velocity on the recording area is constant. In this method, the recording density gradually increases toward the outer periphery of the disk. It has the drawback of going down. In order to eliminate this drawback and increase the recording density, CLV (Constant Linear V
elocity) method or MCAV (Modified Constant Ang
Regular Velocity (MCV) method, MCLV (Modified Constant Linea)
r Velocity) method is adopted.

These systems are configured so that the recording density is almost constant in the inner peripheral portion, the middle portion, and the outer peripheral portion of the disk, but especially in the MCAV type and MCLV type disks, the recording area is arranged along the radial direction of the disk. It is divided into blocks of several to several tens of stages, and the number of sectors in the block increases as it goes to the outer periphery. FIG. 8 is an explanatory view of this format. Reference numeral 7 in the drawing is a prepit set string in which a large number of prepits 8 (see FIG. 9) are arranged. As shown in the figure, the end portions of most of the prepet set rows 7 are displaced from the end portions of the prepet set rows 7 of the adjacent blocks and face the sector portions of the adjacent blocks.

On the other hand, as one of the methods for manufacturing an optical disk, for example, an ultraviolet coin resin is spread between a transparent substrate such as glass and a stamper on which an inversion pattern of a signal pattern is formed, and an inversion pattern of the stamper is formed. There is known a so-called 2P method for transferring a film onto a replica layer.

In this way, a groove (pre-groove) for tracking is formed on the surface of the optical disk, and the laser beam is focused on the spot on the recording layer on the disk surface by the guide of this groove to locally melt it. By this, holes (pripits) were formed and desired information was recorded.

[Problems to be Solved by the Invention] FIG. 9 is an enlarged cross-sectional view in the AA direction in the circle of FIG. In the figure, 3 is a replica layer made of an ultraviolet curable resin or the like, 5 is a recording layer, and 9 is a pre-groove.

By the way, since the recording layer 5 is formed by using a thin film forming technique such as vapor deposition or sputtering, the peripheral surface 10 of the concave pit 8 having a groove deeper than the pregroove 9 has a very thin film thickness. The UV curable resin used for the optical disc has a relatively high water absorption rate of about 2 to 3%. Therefore, during assembly of the optical disk, moisture in the air permeates the replica layer 3 from the peripheral surface 10 of the prepit 8 as indicated by a dotted arrow. As described above, since a large number of prepets 8 are arranged in a row to form the prepit aggregate row 7, the water infiltration locally occurs near the prepite aggregate row 7, and as a result, the replica layer 3 is partially formed. Swell to.

When the prepite set rows 7 of adjacent blocks are arranged directly above each other, there is no problem because the swelling of the replica layer 3 cancels each other in the radial direction of the disk. However, it is extremely rare that the prepet set rows 7 are arranged in a straight line with each other between the blocks, and in most cases, the ends of the prepet set rows 7 face the sector portions of the adjacent blocks. In such a case, as shown in FIG. 9, the swelling of the replica layer 3 extends to the sector portion of the adjacent block, and for that reason, the CL
In V, MCAV, and MCLV systems, the laser pick-up is swung to the left and right of the track over hundreds to thousands of tracks near the boundary between the blocks. Therefore, the tracking noise becomes high, and there is an area (dead zone) that cannot be used for recording, and in an optical disc with a large number of blocks, this dead zone becomes large, and the recording capacity drops significantly. The recording density is lower than that of the CAV method.

An object of the present invention is to provide a method for manufacturing a highly reliable optical information recording medium by solving the drawbacks of the prior art with respect to the CLV system, MCAV system and MCLV system disks and reducing tracking noise. is there.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides at least a transparent substrate and a replica layer provided on the transparent substrate and provided with a large number of signal recesses such as prepits and pregrooves. And an optical information recording medium having a hermetically sealed structure in which the replica layer and the recording layer are shielded from the atmosphere after the assembly is completed, provided with a recording layer formed on the replica layer by a thin film forming technique such as vapor deposition or sputtering. In the manufacturing method, before the replica layer and the recording layer are shielded from the atmosphere, a dehydration step such as baking or vacuum dehydration for removing water that has permeated the replica layer is provided.

[Operation] By removing moisture that has penetrated into the replica layer during the assembly process by dehydration processing such as baking or vacuum dehydration, swelling of the replica layer can be reduced or eliminated, and as a result, tracking noise is reduced. Thus, a highly reliable optical information recording medium can be obtained.

[Embodiment] FIGS. 1A to 1D are process diagrams for explaining a manufacturing process of a recording single plate of an optical disk according to Embodiment 1. FIGS.
As shown in (a) of the figure, the groove (depth 0.09 μm,
Width 0.40 μm) and pit (depth 0.16 μm, width 0.60 μm)
A nickel stamper 1 having an outer diameter of 300 mm and having a diameter of m) is prepared.

Outside diameter 300 after baking silane coupling agent (γ-methacryloxypropyltrimethoxysilane) at 110 ℃ for 30 minutes
The thickness of the resin layer 3 is obtained by pressing the transparent substrate 2 to the stamper 1 side by interposing an ultraviolet curable resin 3 described later between the transparent substrate 2 made of a glass disk having a thickness of 1.2 mm and a thickness of 1.2 mm and the stamper 1. Is maintained at about 80 μm.

Then, as shown in FIG. 1 (b), an energy ray having a light intensity of 150 mw / cm ^{2 at} a wavelength of 320 to 400 nm is irradiated from the transparent substrate 2 side for 30 seconds by using a high-pressure mercury lamp 4, and the ultraviolet curable resin layer 3 is cured to form a replica layer.

Next, as shown in FIG. 1C, the stamper 1 is peeled off from the resin layer 3 (replica layer) to obtain a transparent substrate 2 with an information pattern. Thereafter, as shown in FIG. 1D, a Te—Se—Pb type recording layer 5 is vacuum-deposited on the resin layer 3 to a thickness of 30 nm.

FIG. 2 is a diagram showing a modified example of the recording single plate, and is different from the optical disc shown in FIG. 1 in that the replica layer 3 and the recording layer 5 are different.
A base layer 6 made of nitrocellulose, polytetrafluoroethylene (fluorine resin), or the like is provided between and.

3 to 5 are sectional views of an optical disk using these recording single plates.

In the case of the optical disc shown in FIG. 3, the recording layer 5 side of two recording single plates are placed inside each other, and the recording layer 5 side is laminated with the inner peripheral spacer 11 and the outer peripheral spacer 12 bonded to each other. It has become.

In the case of the optical disc shown in FIG. 4, one recording single plate and one protective plate 13 are attached to each other via the inner peripheral spacer 11 and the outer peripheral spacer 12 so that the recording layer 5 is located inside. It has a record-type Air Sun Germany type structure.

The optical disc shown in FIG. 5 has a single-plate structure in which a moisture-resistant protective layer 14 is formed by coating on the recording layer 5 of the recording single plate.

In any of the structures shown in FIGS. 3 to 5, the recording layer 5 has a closed structure that is shielded from the atmosphere when the optical disc is completely assembled.

CLV, MCAV, or MCLV optical discs having these various structures are usually assembled in the atmosphere, but most of the water penetrates into the replica layer 3 immediately after the recording layer 5 is formed. No, no wetting has occurred. However, until the recording layer 5 is formed as described above and the assembly of the optical disk is completed, in other words, the replica layer 3 and the recording layer 5 are shielded from the atmosphere, Water penetrates from the thin portion, and the replica layer 3 partially swells.

Therefore, if the water absorbed in the replica layer 3 is dehydrated, this deformation can be restored. Baking and vacuum dehydration are effective for this dehydration treatment.

As the baking conditions, for example, a recording single plate having a replica layer and a recording layer formed on a transparent substrate is heated at a temperature between room temperature and about 100 ° C. and a relative humidity of about 40% RH or less at about 30%. Leave it for about 50 minutes to dehydrate, and then assemble the optical disk promptly (for example, within about 30 minutes).

The conditions for vacuum dehydration are as follows: the recording veneer is left in a vacuum chamber having a vacuum degree of 0.1 to 1 Torr for about 12 hours to perform dehydration treatment, and then an optical disc is assembled promptly (for example, within about 30 minutes). In order to shorten the holding time in the vacuum chamber, the recording veneer can be heated to about 100 ° C. or lower in the vacuum chamber.

 Next, a specific example of the dehydration process will be described.

(Specific Example 1) A recording veneer having a replica layer and a recording layer formed on a transparent substrate is left for 2 hours in an atmosphere of 80 ° C. and 20% RH or less for baking, and then the optical disc is heated within 30 minutes. The assembly is completed to form a closed structure.

(Specific Example 2) A recording veneer having a replica layer and a recording layer formed on a transparent substrate is vacuum dehydrated in a vacuum chamber having a vacuum degree of 1 Torr for about 12 hours. Complete the assembly into a closed structure.

Although baking or vacuum dehydration of the recording single plate was performed in the above-described specific example, the present invention is not limited to this, and for example, an optical disc is assembled in an unsealed state, and then dehydration treatment is performed. It is also possible to make a closed structure after processing.

FIG. 6 is a diagram showing a manufacturing example thereof, and as shown in the figure, one moisture removing passage 15 such as a groove or a hole penetrating from the inside to the outside or a plurality of moisture removing passages 15 at predetermined intervals in the circumferential direction. The optical disk is assembled in a non-sealed state by using the formed outer peripheral spacer 12. For example, by leaving this in a vacuum chamber having a vacuum degree of 1 to 2 Torr for 12 hours, the moisture in the replica layer is sucked and removed through the moisture removal passage 15,
Immediately thereafter, the moisture removal passage 15 is closed with an adhesive 16 such as an epoxy resin to form a closed structure.

[Effects of the Invention] FIG. 7 is a noise characteristic diagram of the first and second specific examples and a conventional example in which the dehydration process of the replica layer is not performed. In this figure, the vertical axis represents tracking noise ([noise magnitude of adjacent blocks due to swelling of the replica layer / amplitude of tracking jump signal]), and the horizontal axis represents the number of tracks (distance from the block boundary line). / 1 track pitch) to show the correlation between the two.

The level of tracking noise that has no effect on normal recording / reproduction is 5% or less as shown by the dotted line in FIG.

Therefore, in the case of the conventional one, 40 on the inner side of the block boundary line.
0 tracks, about 400 tracks on the outer circumference, 800 in total
Tracks are not available for recording and are in dead zone. On the other hand, the present invention has low tracking noise, is flat in any track, and can be used near the block boundary line to prevent a decrease in recording capacity.
The advantages of the MCAV method or the MCLV method can be fully exhibited, and a highly reliable optical information recording medium can be manufactured.

[Brief description of drawings]

1 (a) to 1 (d) are manufacturing process diagrams of a recording veneer according to an embodiment of the present invention, FIG. 2 is a sectional view showing a modified example of the recording veneer, FIG. 3, FIG. 4 and FIG. FIG. 5 is a sectional view of an optical disk according to an embodiment of the present invention, FIG. 6 is an explanatory view showing another example of dehydration treatment, FIG. 7 is a tracking noise characteristic view, and FIG.
The figure shows a partially enlarged plan view of an optical disk using the CLV system, MCAV system, or MCLV system. Fig. 9 is A in the circle of Fig. 8.
It is an expanded sectional view of the A line direction. 2 ... Transparent substrate, 3 ... Replica layer, 5 ... Recording layer, 7
…… Prepit assembly line, 8 …… Prepit, 9 …… Pregroove, 15 …… Water removal passage.

Claims (3)

(57) [Claims] 1. A transparent substrate, a replica layer formed on the transparent substrate and having a large number of recesses for signals, and a recording layer formed on the replica layer by a thin film forming technique. In a method for manufacturing an optical information recording medium having a hermetically sealed structure in which the replica layer and the recording layer are shielded from the atmosphere, a dehydration step of removing water that has penetrated into the replica layer before shielding the replica layer and the recording layer from the atmosphere A method for manufacturing an optical information recording medium, characterized by comprising: 2. The method for manufacturing an optical information recording medium according to claim 1, wherein the dehydration step is baking. 3. The method for manufacturing an optical information recording medium according to claim 1, wherein the dehydration step is a vacuum dehydration process.