JP2003157592A - Optical recording medium and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an optical recording medium which can effectively expel an optical recording medium of which the defect projects largely from the surface of a light transmission layer. SOLUTION: The method of manufacturing the optical recording medium which has at least the light transmission layer 3 and a recording layer 2 and with which the recording and/or reproducing of data is performed by irradiating the recording layer 2 with a laser beam through the light transmission layer 3 includes at least a projecting defect inspection process step of detecting the projecting defect 14 sticking to the light transmission layer 3 or projecting from the light transmission layer 3. As a result, the optical recording medium of which the defects projects largely from the surface of the light transmission layer 3 can be effectively expelled and therefore the optical recording medium having a high possibility of such defect coming into collision against an objective lens or a support for supporting the same can be expelled.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical recording medium, and more particularly to an optical recording medium having a thin light transmitting layer.
The present invention also relates to a method for manufacturing an optical recording medium, and in particular,
The present invention relates to a method for manufacturing an optical recording medium having a thin light transmitting layer.

[0002]

2. Description of the Related Art Conventionally, optical recording media represented by CD and DVD have been widely used as recording media for recording digital data. In reading data from such an optical recording medium, so-called error correction processing is performed, and if the read data contains an error, this is corrected and restored to correct data. . The level of error that can be corrected by the error correction process differs depending on the algorithm, but if the level of error exceeds this level, the error cannot be corrected anymore, and the data before and after the adjacent data is used. Compensation data is generated.

One of the main causes of such data error is the presence of defects contained in the light transmitting layer in the optical recording medium. Defects contained in the light transmitting layer include the inclusion of foreign matter and the generation of bubbles. Generally, the larger the size of the defect, the higher the level of error that occurs in the data. Therefore, when manufacturing an optical recording medium, a predetermined allowable size (critical value) is set for defects contained in the light transmitting layer so that a high level error that cannot be corrected even by an error correction process does not occur. If the light transmitting layer contains a defect having a size larger than this, the optical recording medium is treated as a defective product.

Generally, in the error correction process, if the maximum size of the defect contained in the light transmitting layer exceeds a predetermined value, the possibility that the error cannot be corrected rapidly increases. Therefore, conventionally, in the manufacture of an optical recording medium, the critical value of the defect contained in the light transmitting layer is set according to such a predetermined value, and the defect having a size exceeding the critical value is contained in the light transmitting layer. In such cases, it was usual to handle the optical recording medium as a defective product.

[0005]

By the way, in recent years, in order to record a large amount of digital data, the light transmitting layer of an optical recording medium is made thin and a laser beam used for reading data is converged. A technique for setting a very small distance (working distance) between the objective lens and the surface of the optical recording medium has attracted attention. If the light transmission layer is thinned and the working distance is set narrow as described above, the effective spot of the laser beam can be narrowed down to an extremely small value as compared with the conventional case, so that higher density recording can be performed.

However, as a result of the thinning of the light transmitting layer, when the film thickness is close to or smaller than the size of the defect which is more likely to be uncorrectable by the error correction process, the light transmitting layer is included in the light transmitting layer. If the critical value of the defect is set to the same size as the size of the defect that is more likely to be uncorrectable by the error correction process, then even if the optical recording medium has a large protrusion from the surface, it is treated as a good product. There is a possibility that As described above, since the working distance is set to be extremely narrow when reading data from this type of optical recording medium, when an optical recording medium having a large defect protruding from the surface is treated as a good product, it is projected. Defects may come into contact with the objective lens or the support that supports it.

Therefore, an object of the present invention is to provide an optical recording medium in which the defects protruding from the surface of the light transmitting layer are reduced.

Yet another object of the present invention is to provide an improved optical recording medium having a thin light transmitting layer.

Still another object of the present invention is to provide an optical recording medium manufacturing method capable of effectively eliminating an optical recording medium having a large number of defects protruding from the surface of the light transmitting layer. .

Yet another object of the present invention is to provide an improved method of manufacturing an optical recording medium having a thin light transmitting layer.

[0011]

The object of the present invention is to:
A method of manufacturing an optical recording medium, comprising at least a light transmitting layer and a recording layer, wherein data is reproduced and / or recorded by irradiating the recording layer with a laser beam through the light transmitting layer. It is achieved by a method for manufacturing an optical recording medium, which comprises at least a protruding defect inspection step of detecting a protruding defect adhered to or protruding from the light transmitting layer.

According to the present invention, it is possible to effectively eliminate an optical recording medium having a large number of defects protruding from the surface of the light transmitting layer, so that the defects come into contact with the objective lens and the support that supports it. It is possible to eliminate an optical recording medium that has a high risk. For this reason, especially
It is suitable for manufacturing an optical recording medium for recording / reproducing data with a small distance set.

In a preferred embodiment of the present invention, the thickness of the light transmitting layer is 50 to 150 μm.

In a further preferred aspect of the present invention, in the projecting defect inspection step, the critical value of the projecting defect height is selected within the range of about 1 μm to about 120 μm.

In a further preferred aspect of the present invention, the critical value for the height is selected in the range of about 2 μm to about 100 μm.

[0016] In a further preferred aspect of the present invention, the critical value of the height is selected within the range of about 5 µm to about 50 µm.

In a further preferred aspect of the present invention, the method further includes an internal defect inspection step of detecting an internal defect included in the light transmitting layer, wherein the internal defect inspection step is performed in the first direction of the internal defect. The critical value and the critical value in the second direction different from the first direction are set to different values.

According to a further preferred embodiment of the present invention, since the critical values of the internal defect size are defined separately from the two directions, the yield can be significantly reduced by setting these critical values appropriately. Without letting
It becomes possible to effectively eliminate defective disks.

In a further preferred aspect of the present invention, the first direction is a direction substantially perpendicular to the optical axis of the laser light, and the second direction is the optical axis of the laser light. In contrast, it is a substantially horizontal direction.

In a further preferred aspect of the present invention, the critical value in the first direction is larger than the critical value in the second direction.

The above-mentioned object of the present invention is also provided with at least a light transmitting layer and a recording layer, and light for reproducing and / or recording data by irradiating the recording layer with a laser beam through the light transmitting layer. In the recording medium, the height of the largest protruding defect having the maximum height from the surface of the light transmitting layer among the protruding defects attached to the light transmitting layer or protruding from the light transmitting layer has a height of about 1 μm to about. It is achieved by an optical recording medium characterized by having a thickness of 120 μm.

According to the present invention, since the height of the protruding defect is suppressed, the possibility of such defect contacting the objective lens and the support that supports it during data recording / reproduction is greatly reduced. To do. For this reason, especially
It is suitable for an optical recording medium for recording / reproducing data with a small distance set.

In a preferred embodiment of the present invention, the maximum protruding defect has a height of about 2 μm to about 100 μm.

In a further preferred aspect of the present invention, the height of the maximum protruding defect is about 5 μm to about 50 μm.

In a further preferred aspect of the present invention, the internal defect contained in the light-transmitting layer has a maximum length in the first direction, which is greater than a length of the first maximum internal defect in the direction. Among the internal defects included in the light transmitting layer, the length of the second maximum internal defect having the maximum length in the second direction is shorter than that of the second maximum internal defect.

According to a further preferred embodiment of the present invention, the length of the second largest internal defect in the second direction is shorter than the length of the first largest internal defect in the first direction. In addition, the yield is not significantly reduced during manufacturing.

In a further preferred aspect of the present invention, the first direction is substantially perpendicular to the optical axis of the laser light, and the second direction is the optical axis of the laser light. In contrast, it is a substantially horizontal direction.

In a further preferred aspect of the present invention, the thickness of the light transmitting layer is 50 to 150 μm.

The above object of the present invention is also a light which comprises at least a light transmitting layer and a recording layer, and by which the recording layer is irradiated with a laser beam through the light transmitting layer to reproduce and / or record data. In the method of manufacturing the recording medium,
At least a protruding defect inspection step of detecting a protruding defect attached to the light transmitting layer or protruding from the light transmitting layer is included. This is achieved by a method for manufacturing an optical recording medium, characterized in that the critical value in the second direction different from the one direction is set to a different value.

According to the present invention, it is possible to effectively eliminate a defective disk that is highly likely to have a protruding defect in contact (crash) with the objective lens or a support body that supports the objective lens, and significantly reduce the yield. It is possible to effectively eliminate a defective disk having a protruding defect that may cause an error of a level that cannot be corrected by the error correction process.

In a preferred embodiment of the present invention, the thickness of the light transmitting layer is 50 to 150 μm.

In a further preferred aspect of the present invention, the first direction is a direction substantially perpendicular to the optical axis of the laser light, and the second direction is an optical axis of the laser light. In contrast, it is a substantially horizontal direction.

In a further preferred aspect of the present invention, the critical value in the first direction is larger than the critical value in the second direction.

[0034]

DETAILED DESCRIPTION OF THE INVENTION Referring to the accompanying drawings,
A preferred embodiment of the present invention will be described in detail.

A method of manufacturing an optical recording medium according to a preferred embodiment of the present invention roughly includes a film forming step and an inspection step. The film forming step is a step for forming a plurality of layers forming the optical recording medium, and the inspection step is a step for inspecting the optical recording medium produced by the film forming step for defects. Hereinafter, each of these steps will be described.

FIG. 1 is a flow chart schematically showing the film forming process.

As shown in FIG. 1, in the film forming process, first, a substrate 1 having a groove on one surface and a center hole 4 in the center thereof is manufactured (step S1). Here, the substrate 1 can be manufactured by using a die in which a stamper having irregularities corresponding to the grooves is arranged and injecting a molten material into the die. The material of the substrate 1 is not particularly limited, but polycarbonate is preferably used. Here, the thickness of the substrate 1 is not particularly limited, but is set to about 1.1 mm in this embodiment.

Next, the recording layer 2 is formed on the surface of the substrate 1 on which the groove is provided (step S2). It is preferable to use a sputtering method for forming the recording layer 2. The structure of the recording layer 2 is not particularly limited, but preferably has a multilayer structure including at least a phase change film. In this case, it is more preferable to include a dielectric film as a protective film for the phase change film. However, it is not essential for the recording layer 2 to include a phase change film, and various known recordable layers may be used, and it is a read-only recording layer in which information is recorded in advance. It doesn't matter. Here, the thickness of the recording layer 2 is not particularly limited, but is set to about 40 nm in the present embodiment.

Next, the light transmission layer 3 is formed on the recording layer 2 (step S3). Although not particularly limited, it is preferable to use an ultraviolet curable resin as the material of the light transmitting layer 3, and it is preferable to use a spin coating method for forming the same. The light transmitting layer 3 may have a single-layer structure or a multi-layer structure having a hard coat film as the outermost layer. Here, the thickness of the light transmitting layer 3 is not particularly limited, but in the present embodiment, it is set to 50 to 150 μm, preferably about 100 μm.

FIG. 2 is a sectional view schematically showing the structure of the optical recording medium manufactured by the above-mentioned film forming process.

As shown in FIG. 2, in the optical recording medium manufactured by the above-mentioned film forming process, laser light is substantially perpendicular to the recording layer 2 from the surface side on which the light transmitting layer 3 is formed. Data can be reproduced and / or recorded by irradiating the. Although not particularly limited, the laser beam used for reproducing and / or recording data on such an optical recording medium is, for example, about 405 nm.
It is possible to use laser light having a wavelength of.

In the optical recording medium having such a structure, the NA (numerical aperture) of the objective lens for converging the laser light is increased to, for example, 0.8 or more, and the effective laser light applied to the recording layer 2 is obtained. Since high density recording is performed by narrowing the spot to an extremely small size, the film thickness of the light transmitting layer 3 is set to be extremely thin (about 100 μm) as described above, and further, the distance from the surface of the optical recording medium (working It is necessary to set the distance) to a very small value, for example, about 130 μm.

Next, the inspection process will be described.

FIG. 3 is a flow chart schematically showing the inspection process.

As shown in FIG. 3, in the inspection process, first, a defect (protrusion defect) protruding from the light transmitting layer 3 is detected.
Then, it is inspected whether or not there is a defect in which the height of the protruding portion exceeds the first critical value (step S4). Here, the defects refer to all the elements that impede the straight traveling of the laser light in the light transmitting layer 3, such as foreign substances mixed in the light transmitting layer 3 and bubbles generated or sealed inside the light transmitting layer 3.
As a result of the inspection, when it is determined that the protruding defect exceeding the first critical value exists, the optical recording medium is treated as a defective product (step S5). Although not particularly limited, the inspection of the protruding defect in step S4 can be performed using a surface shape measuring microscope.

Considering that the working distance is about 130 μm, the first critical value is about 1
It is preferable to select in the range of μm to about 120 μm. When the first critical value is set to less than 1 μm, the optical recording medium is treated as a defective product due to the presence of protruding defects at a level that does not actually affect the reproduction and / or recording of data. If the first critical value is set to a value exceeding 120 μm, the projection defect may come into contact (crash) with the objective lens or the support that supports it due to fluctuations in the working distance during actual use. A high-quality optical recording medium may be handled as a good product. Also, the first
It is more preferable to select the critical value of within the range of about 2 μm to about 100 μm. If the first critical value is selected within this range, the yield can be further improved while preventing the occurrence of crashes more effectively. Furthermore, the first critical value is about 5 μm.
It is particularly preferable to select in the range of about 50 μm. If the first critical value is selected within this range, the yield can be further improved while preventing the occurrence of crashes more effectively.

FIGS. 4A to 4D are schematic cross-sectional views of optical recording media having protruding defects 11 to 14, respectively.

A part of the protruding defect 11 shown in FIG. 4A is buried in the light transmitting layer 3, and the remaining part protrudes from the surface of the optical recording medium. However, FIG.
Since the height of the protruding defect 11 shown in (a) is less than or equal to the first critical value, it does not serve as the basis for determining that the optical recording medium is defective in step S4.

Further, the protruding defect 12 shown in FIG.
However, a part thereof is buried in the light transmitting layer 3 and the remaining part is projected from the surface of the optical recording medium. However, the height of the protruding defect 12 exceeds the first critical value. Therefore, the optical recording medium is determined to be defective in step S4.

On the other hand, the protruding defect 13 shown in FIG.
Are not buried in the light transmitting layer 3 and exist in a state of being attached to the surface of the light transmitting layer 3. However, FIG.
Since the height of the protruding defect 13 shown in (c) is less than or equal to the first critical value, it does not serve as a basis for determining that the optical recording medium is defective in step S4.

Further, the protruding defect 14 shown in FIG.
Is not buried in the light transmitting layer 3 and is present in a state of being attached to the surface of the light transmitting layer 3.
Since its height exceeds the first critical value, the optical recording medium is determined to be defective in step S4.

If it is determined in step S4 that there are no protruding defects exceeding the first critical value, then some or all of the defects (internal defects) buried in the light transmitting layer 3 are detected. Then, it is inspected whether or not there is an internal defect exceeding at least one of the second critical value and the third critical value (step S6). As a result of such inspection, the second
If it is determined that there is an internal defect exceeding at least one of the third and the third critical values, the optical recording medium is treated as a defective product (step S5), and at least one of the second and the third critical values is treated. If it is determined that there are no more internal defects than the above, the optical recording medium is treated as a non-defective product in this inspection process (step S7). still,
Although not particularly limited, the inspection of the internal defect in step S6 can be performed by irradiating the light transmitting layer 3 with a laser beam for inspection from an oblique direction and measuring the amount of the reflected light. .

Here, the second critical value is the critical value of the length of the internal defect, and the length in the direction perpendicular to the optical axis of the laser light (horizontal direction to the surface of the optical recording medium). Is the critical value of On the other hand, the third critical value is also the critical value of the length of the internal defect, and is the critical value of the length in the horizontal direction (the direction perpendicular to the surface of the optical recording medium) with respect to the optical axis of the laser light. It is a value. As described above, in this embodiment, the critical value of the internal defect size is defined separately from the two directions.

Here, as the second and third critical values,
It is preferable to set in consideration of the size of a defect that increases the possibility that correction cannot be performed by the error correction process. Specifically, when a general error correction process is used, the size of a defect that increases the possibility of being unable to correct is about 200 μm.
It is about m. However, in this embodiment,
Since the light transmission layer 3 of the optical recording medium to be inspected is thin (about 100 μm), internal defects having a long length in the horizontal direction (vertical direction to the surface of the optical recording medium) with respect to the optical axis of the laser beam are generated. Most of the optical recording media that it has are eliminated in step S4. Therefore, in the present embodiment, it is possible to set the second critical value larger than the size of the defect that increases the possibility of being uncorrectable.

Specifically, the second critical value is about 3
It is preferable to select within the range of 0 μm to about 500 μm. If the second critical value is set to less than 30 μm,
In reality, since the optical recording medium is treated as a defective product due to the presence of internal defects having a level that does not affect the reproduction and / or recording of data, the yield may be excessively deteriorated, and the second critical value may be 500 μm. If the value is set to be larger than, there is a possibility that an optical recording medium having a defect of a level that cannot be corrected by the error correction process is treated as a good product. The second critical value is about 40 μm
More preferably, it is selected within the range of about 300 μm. If the second critical value is selected within this range, the occurrence of uncorrectable errors can be prevented more effectively,
The yield can be further improved. Furthermore, the second
It is particularly preferable to select the critical value of in the range of about 50 μm to about 200 μm. If the second critical value is selected within such a range, the yield can be further improved while preventing the occurrence of uncorrectable errors more effectively.

It is most preferable that the second critical value is substantially the same as the size of the defect, which increases the possibility that the correction cannot be performed by the error correction process. In the present embodiment, it is set to about 200 μm. Is most preferred.

On the other hand, the third critical value is about 10 μm.
It is preferred to choose a value less than the second critical value within the range of about 220 μm. The third critical value is 10
If it is set to less than μm, the yield may be deteriorated excessively, and if the third critical value is set to a value exceeding 220 μm, an optical recording medium containing a defect of a level that cannot be corrected by the error correction process is treated as a good product. There is a risk. Further, as the third critical value, it is more preferable to select a value smaller than the second critical value within the range of about 30 μm to about 200 μm. If the third critical value is selected within this range, the yield can be further improved while more effectively preventing the occurrence of uncorrectable errors. Furthermore, as the third critical value, about 50
It is particularly preferred to choose a value smaller than the second critical value in the range from μm to about 100 μm. If the third critical value is selected within this range, the yield can be further improved while preventing the occurrence of uncorrectable errors more effectively.

It is most preferable that the third critical value is substantially the same as the film thickness of the light transmitting layer 3, and in the present embodiment, it is most preferably set to about 100 μm. Further, considering the yield, the third critical value may be set larger than the film thickness of the light transmission layer 3.

FIG. 5A is a schematic plan view of the optical recording medium having the internal defect 21, and FIG. 5B is a schematic sectional view thereof.

In the internal defect 21 shown in FIGS. 5A and 5B, the maximum value of the length in the direction perpendicular to the optical axis of the laser light exceeds the second critical value, and The maximum length in the horizontal direction with respect to the optical axis of
Exceeds the critical value of. Therefore, the optical recording medium having such an internal defect 21 is determined to be a defective product in step S6.

FIG. 6A is a schematic plan view of the optical recording medium having the internal defect 22, and FIG. 6B is a schematic sectional view thereof.

In the internal defect 22 shown in FIGS. 6A and 6B, the maximum value of the length in the direction perpendicular to the optical axis of the laser light exceeds the second critical value. The maximum value of the length in the horizontal direction with respect to the optical axis of does not exceed the third critical value. The optical recording medium having such an internal defect 22 is also determined to be a defective product in step S6.

FIG. 7A is a schematic plan view of an optical recording medium having internal defects 23, and FIG. 7B is a schematic sectional view thereof.

In the internal defect 23 shown in FIGS. 7A and 7B, the maximum value of the length in the direction perpendicular to the optical axis of the laser light does not exceed the second critical value. The maximum value of the length in the horizontal direction with respect to the optical axis of is above the third critical value. The optical recording medium having such an internal defect 23 is also determined to be a defective product in step S6.

FIG. 8A is a schematic plan view of an optical recording medium having internal defects 24, and FIG. 8B is a schematic sectional view thereof.

In the internal defect 24 shown in FIGS. 8A and 8B, the maximum value of the length in the direction perpendicular to the optical axis of the laser light does not exceed the second critical value, and The maximum length in the horizontal direction with respect to the optical axis of the laser light is the third
The critical value of is not exceeded. Such an internal defect 24 is
In step S6, it is not the basis for determining that the optical recording medium is defective.

As described above, in step S6, the critical value of the internal defect size is defined separately from the two directions, and the critical value of the length in the direction perpendicular to the optical axis of the laser light (second critical value) is determined. ) Is set to be longer than the critical value (23rd critical value) of the length in the horizontal direction with respect to the optical axis of the laser light. Therefore, defective disks can be effectively eliminated without significantly reducing the yield.

As described above, according to this embodiment, in the inspection step, it is inspected whether or not there is a protruding defect in which the height of the protruding portion exceeds the first critical value. In step S4), it is possible to effectively eliminate a defective disk having a high possibility that a protruding defect will come into contact (crash) with the objective lens or a support body supporting the objective lens.

Further, in the present embodiment, in the inspection of the internal defect (step S6), the judgment is performed by using the second and third critical values having different values, so that the yield is remarkably reduced. Without doing so, it is possible to effectively eliminate a defective disk having an internal defect that may cause an error of a level that cannot be corrected by the error correction process.

Next, another preferable inspection process will be described.

FIG. 9 is a flowchart schematically showing another preferable inspection process, which is performed instead of or in addition to the inspection process described with reference to FIG.

As shown in FIG. 9, in this inspection step, first, at least one of the fourth critical value and the fifth critical value is a protruding defect in which at least a part of the light transmitting layer 3 protrudes. It is inspected whether or not there are protruding defects exceeding the number (step S8). As a result of the inspection, when it is determined that the internal defect exceeding at least one of the fourth and fifth critical values exists, the optical recording medium is treated as a defective product (step S5), and the fourth and fifth.
If it is determined that there is no internal defect exceeding at least one of the critical values of, the optical recording medium is treated as a non-defective product in this inspection process (step S7).
Although not particularly limited, the inspection of the protruding defect in step S8 can be performed using a surface shape measuring microscope.

Here, the fourth critical value is the critical value of the height of the protruding portion of the protruding defect. On the other hand, the fifth critical value is
Similarly, it is a critical value of the length of the protruding portion of the protruding defect, and is a critical value of the length in the direction perpendicular to the optical axis of the laser light (horizontal direction to the surface of the optical recording medium). As described above, in this inspection process, the critical value of the size of the protruding portion is defined separately from the two directions.

Here, the fourth critical value is preferably selected within the range of about 1 μm to about 120 μm, like the above-mentioned first critical value, and about 2 μm to about 100 μm.
More preferably, it is selected within the range of μm,
It is particularly preferable to select within the range of about 5 μm to about 50 μm. The fifth critical value is preferably selected within the range of about 30 μm to about 500 μm, like the second critical value described above, and is about 40 μm to about 3 μm.
It is more preferable to select in the range of 00 μm, and it is particularly preferable to select in the range of about 50 μm to about 200 μm.

As described above, in this inspection process, since the critical value of the size of the protruding portion is defined separately from the two directions (step S8), the protruding defect on the objective lens or the supporting body for supporting the same is obtained. It is possible to effectively eliminate defective disks that are likely to come into contact (crash) with each other, and to produce a protruding defect that can cause an error that cannot be corrected by error correction processing without significantly lowering the yield. It is possible to effectively eliminate the defective disk having

The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. It goes without saying that it is a thing.

For example, in the above-mentioned embodiment, the preferable range of the value to be selected as the first critical value is specified, but such a value is specified based on the working distance, and the present invention is based on this. It is not limited. Therefore, when the working distance is different from that of the above-mentioned embodiment, the appropriate first critical value may be selected accordingly.

In the above embodiment, the preferable range of the values to be selected as the second and third critical values is specified. However, such a value causes an error of a level that cannot be corrected by the error correction processing. It is specified based on the size of the obtained internal defect, and the present invention is not limited to this. Therefore, if the size of the internal defect that may cause an error that cannot be corrected by the error correction process is different from that in the above embodiment, appropriate second and third critical values may be selected accordingly. Good.

Further, in the film forming step in the above embodiment, the recording layer 2 and the light transmitting layer 3 are formed on the substrate 1 in this order. On the contrary, the recording layer is formed on the light transmitting layer 3. 2 and the substrate 1 may be formed in this order.

In the inspection process of the above embodiment, the inspection of the internal defects (step S6) is performed after the inspection of the protruding defects (step S4) is completed, but the order may be reversed.

[0081]

As described above, according to the present invention,
It is possible to effectively eliminate a defective disk having a protrusion defect in which the protrusion amount from the surface of the light transmission layer is large. Here, since the protrusion from the surface of the light transmitting layer becomes a problem particularly in the optical recording medium in which the working distance is set narrow at the time of recording / reproducing, the present invention provides an optical recording medium having a thin light transmitting layer and the same. It is particularly suitable for manufacturing methods.

[Brief description of drawings]

FIG. 1 is a flowchart schematically showing a film forming process.

FIG. 2 is a cross-sectional view schematically showing a structure of an optical recording medium manufactured by a film forming process.

FIG. 3 is a flowchart schematically showing an inspection process.

4A to 4D are protrusion defects 11 to 1 respectively.
4 is a schematic cross-sectional view of an optical recording medium having No. 4.

5A is a schematic plan view of an optical recording medium having an internal defect 21, and FIG. 5B is a schematic sectional view thereof.

6A is a schematic plan view of an optical recording medium having an internal defect 22, and FIG. 6B is a schematic sectional view thereof.

7A is a schematic plan view of an optical recording medium having an internal defect 23, and FIG. 7B is a schematic sectional view thereof.

8A is a schematic plan view of an optical recording medium having an internal defect 24, and FIG. 8B is a schematic sectional view thereof.

FIG. 9 is a flowchart schematically showing another preferable inspection process.

[Explanation of symbols]

1 substrate 2 recording layers 3 Light transmission layer 4 center hall 11-14 Projection defect 21-24 Internal defect

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Claims (11)

[Claims] 1. A light-transmissive layer and a recording layer are provided at least,
In a method of manufacturing an optical recording medium in which data is reproduced and / or recorded by irradiating the recording layer with a laser beam through the light transmitting layer, the method adheres to the light transmitting layer or protrudes from the light transmitting layer. A method for manufacturing an optical recording medium, comprising at least a protrusion defect inspection step of detecting a protrusion defect. 2. The thickness of the light transmitting layer is 50 to 150 μm.
The method of manufacturing an optical recording medium according to claim 1, wherein 3. The projection defect inspection step, wherein the critical value of the height of the projection defects is selected within the range of about 1 μm to about 120 μm.
A method for manufacturing the optical recording medium according to. 4. The critical value of the height is about 2 μm to about 100.
The method for manufacturing an optical recording medium according to claim 3, wherein the optical recording medium is selected within a range of μm. 5. The height critical value is about 5 μm to about 50 μm.
The method for producing an optical recording medium according to claim 4, wherein the optical recording medium is selected within the range of m. 6. A light-transmitting layer and a recording layer are provided,
An optical recording medium for reproducing and / or recording data by irradiating the recording layer with a laser beam through the light transmitting layer, the protrusion being attached to the light transmitting layer or protruding from the light transmitting layer. Among the defects, the height of the maximum protruding defect having the maximum height from the surface of the light transmission layer is about 1 μm.
An optical recording medium characterized by having a thickness of m to about 120 μm. 7. The film thickness of the light transmitting layer is 50 to 150 μm.
7. The optical recording medium according to claim 6, wherein 8. At least a light transmitting layer and a recording layer are provided,
In a method of manufacturing an optical recording medium in which data is reproduced and / or recorded by irradiating the recording layer with a laser beam through the light transmitting layer, the method adheres to the light transmitting layer or protrudes from the light transmitting layer. At least a protrusion defect inspection step of detecting a protrusion defect is included, and in the inspection step, a threshold value in a first direction of a protrusion of the protrusion defect and a threshold value in a second direction different from the first direction. Are set to different values. 9. The thickness of the light transmitting layer is 50 to 150 μm.
9. The method for manufacturing an optical recording medium according to claim 8, wherein 10. The direction in which the first direction is substantially perpendicular to the optical axis of the laser light and the second direction is substantially horizontal in the optical axis of the laser light. 10. The method for manufacturing an optical recording medium according to claim 8, wherein: 11. The method of manufacturing an optical recording medium according to claim 10, wherein the critical value in the first direction is larger than the critical value in the second direction.