JP2002237100A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording medium which is specially suitable for a civilian DVD-R. SOLUTION: The optical recording medium manufactured by forming a recording layer containing organic dyestuff and a reflecting layer on a disklike substrate formed with a guide groove is characterized by that the depth and/or width of the guide groove is increased from the inner periphery to the outer periphery of the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical recording medium having an organic dye as a recording layer, and more particularly to a consumer DVD-R.

[0002]

2. Description of the Related Art In recent years, for high-density recording of an optical recording medium,
Attention has been paid to shortening the oscillation wavelength of a recording / reproducing laser beam, and a wavelength of 780 n is generally used for a CD-based optical recording medium.
As an optical recording medium capable of recording and reproducing with a laser beam having a wavelength shorter than m and 830 nm, a DVD-based optical recording medium using a semiconductor laser beam having a wavelength of 630 nm to 680 nm for recording and reproducing has been developed.

[0003] Various types of such optical recording media have been proposed. Among them, organic dye-based optical recording media include:
It has the features of being inexpensive and easy to manufacture in terms of process. With respect to the organic dye-based optical recording medium, a wavelength of 640 has recently been used.
The standard of a 3.95 GB capacity of a write-once optical recording medium (DVD-R) that performs recording and reproduction with a laser beam in the vicinity of nm has been established. A method for controlling the edge has been established, and a system optimal for high-density recording has been put to practical use on a recording apparatus.

Recently, however, the demand for DVD-Rs for consumer use has increased, and wavelengths of 660 nm to 67
Wavelength of 640 nm using a semiconductor laser near 0 nm.
An optical recording medium capable of performing optical recording at a high density equivalent to the use of a nearby laser beam is being developed. On the other hand, when the optical recording medium is used for a computer, CAV, which records from the innermost circumference to the outermost circumference at the same angular velocity, is usually used.
ZCAV (constant angular velocity recording method) is required. In that case, it is required to have a recording sensitivity corresponding to a linear velocity of 1 × to 2 × or higher in one medium surface, or to have a small recording speed dependency.

[0005]

The consumer DVD-R according to the present invention has stable and good recording characteristics with respect to drives of various design concepts depending on manufacturers, including inexpensive ones. Is required. The main specifications to be satisfied by the recorded medium are already existing DVD-
It is equivalent to the specifications of ROM and DVD-Video media, and in order to realize it, the characteristics in the unrecorded medium surface at a radius of 23 to 58.3 mm from the center of the media (in the DVD-R standard, It is described as "unrecorded disc specifications", and includes a push-pull signal, etc. Hereinafter, the uniformity of the unrecorded characteristics and the recording characteristics (DVD-R standard) In this document, it is described as "recorded disc specifications", and includes recording sensitivity, jitter characteristics, error rate, etc.).

It is also essential to provide a medium which is inexpensive and has excellent durability.

[0007]

Means for Solving the Problems Stable and good recording can be performed in any user zone (the area where the guide groove is provided and where information can be recorded) in the inner, middle and outer peripheral portions of the optical recording medium. The inventors of the present invention have made intensive studies and have reached the present invention described below. That is, the present invention
(1) In an optical recording medium in which a recording layer containing an organic dye and a reflective layer are formed on a disk-shaped substrate on which a guide groove is formed, the groove depth and / or groove width of the guide groove is set to An optical recording medium characterized by increasing from an inner circumference to an outer circumference. (2) In an optical recording medium in which a recording layer containing an organic dye and a reflection layer are formed on a disc-shaped substrate having a guide groove formed thereon, preformat information is formed as land prepits. The maximum length in the direction parallel to the guide groove at the bottom of the prepit is 0.20
An optical recording medium having a thickness of from 0.31 μm to 0.31 μm. And (3) in an optical recording medium in which a recording layer containing an organic dye and a reflection layer are formed on a disk-shaped substrate, the surface deflection acceleration of the recording layer forming surface of the optical recording medium is ± 5 m / s ² or less. An optical recording medium characterized by the following.

[0008]

Embodiments of the present invention will be described below. In the optical recording medium of the present invention, the portion of the recording layer irradiated with the recording laser light is heated by absorbing the laser light to reach the decomposition temperature of the organic dye (the main temperature at which the main dye starts to be described later). As the organic dye decomposes and decomposes, the film thickness decreases and the optical properties of that portion change, resulting in a change in the phase of the return light, and in addition, a change in reflectivity due to the flow deformation of the substrate. In this case, recording is performed by performing the recording, and reproduction is performed by detecting a change in the reflectance.

In the present invention, a known substrate such as a resin such as polycarbonate, polymethacrylate and amorphous polyolefin is used as the transparent substrate, and has a guide groove for tracking servo. Generally, in an organic dye-based optical recording medium, the optimum range of the track pitch and the groove depth of the guide groove provided on the substrate depends on the wavelength of the recording / reproducing light.

For example, in the case of an optical recording medium for recording / reproducing at a wavelength of 600 nm to 700 nm, the groove depth is 100 to
180 nm is preferable, and 140 to 180 nm is more preferable. In the case of an optical recording medium for recording / reproducing at a wavelength of 400 nm to 500 nm, the groove depth is preferably 80 to 150 nm. When the lower limit of the groove depth is less than 80 nm, it may be difficult to obtain a sufficient recording modulation degree and obtain a sufficient push-pull signal. It tends to be difficult to obtain a high reflectance.

However, when a recording layer is formed by spin-coating a solution containing an organic dye on such a substrate, it is difficult to dry the solvent or to spread the liquid from the inner circumference to the outer circumference. There was a tendency for the film to be too thick and the grooves to be filled too much. As a result, D _g in FIG. 2, that is, the film thickness of the groove portion of the recording layer corresponding to the guide groove (hereinafter, simply referred to as “film thickness of the groove portion of the recording layer”) changes from the inner circumference to the outer circumference. There was a problem that uniformity of various characteristics such as a push-pull signal and recording sensitivity in the medium surface could not be obtained, the sensitivity became insufficient at the outer periphery, errors increased, and the quality of video and data at the outer periphery deteriorated.

The present inventors have found that in order to prevent this, it is preferable to increase the groove depth and / or groove width of the guide groove from the inner periphery to the outer periphery of the substrate. By increasing the groove depth from the inner periphery toward the outer periphery, it is possible to prevent the grooves of the recording layer (grooves formed on the recording layer surface corresponding to the guide grooves on the substrate) from being excessively filled by spin coating.

When the thickness of the recording layer formed by spin coating is increased at the outer periphery, the width of the groove in the recording layer is reduced, and the recording sensitivity is likely to be reduced. However, the groove width is increased from the inner periphery toward the outer periphery. This can alleviate a decrease in recording sensitivity. Further, by increasing the groove width, it is possible to alleviate the reduction in the transferability of the substrate at the outer peripheral portion of the substrate. Therefore, increasing the depth of the guide groove in the outer peripheral portion of the substrate is particularly effective for achieving uniformity of the unrecorded characteristics such as push-pull mainly over the entire medium surface, and increasing the groove width in the outer peripheral portion. Is particularly effective in realizing the uniformity of the recording sensitivity over the entire medium surface, the uniformity of the resulting jitter, and the uniformity of the error rate (PI error).

The depth of the guide groove of the substrate is determined by measuring the optical groove shape.
The range from 140 to 155 nm is preferred. If the depth is smaller than 140 nm, a sufficient recording modulation degree may not be obtained, and a sufficient push-pull tends to be hardly obtained. 155nm
If it is deeper, the transfer of the groove at the time of forming the substrate tends to be difficult. A radius of 45 from the center of the circle on the outer periphery of the substrate
The groove depth in mm is preferably 5 to 9 nm deeper than in a radius of 25 mm. If it is shallower than 45 nm, sufficient push-pull uniformity may not be obtained. If it exceeds 9 nm, on the contrary, it may be too deep, which may impair push-pull uniformity.

Alternatively, the groove depth of the guide groove of the substrate measured by AFM (atomic force microscope) is 150 to 180 nm, and the groove depth at a radius of 58 mm from the center is 23 mm.
It is preferably 5 to 20 nm deeper than in mm. In the present invention, the optical groove shape measurement and AF
Two methods were introduced: measurement by M. The optical groove shape was measured using DGM-DVD-TII He-Cd 325 nm manufactured by FUSO ELECTRONICS CO., LTD. The AFM used was Digital Instruments Nanoscope II.

The value of the groove depth obtained by the optical groove shape measurement may be different from the value of the groove depth obtained by the AFM measurement. This is mainly due to the fact that the part to be measured is slightly different.
As shown in FIG. 6, when the groove depth is measured by the AFM, the height difference b between the highest part of the adjacent land (the top part of the convex part when convexly curved) and the bottom part of the groove part is used. _{It is considered} that _sub2 is measured, and in the optical groove shape measurement, the height difference b _sub1 between the start point of the curved portion of the land and the bottom of the groove is measured. Therefore, the groove depth is likely to be larger in the AFM measurement than in the optical groove shape measurement by the height of the curvature of the land.

Therefore, in the optical recording medium according to the present invention, the depth of the guide groove of the substrate in the optical groove shape measurement is 140 to 155.
The groove depth at a radius of 45 mm from the center is 5 to 9 nm deeper than that at a radius of 25 mm, or the groove depth measured by AFM of the guide groove of the substrate is 150 to 1
It is preferably 80 nm, and the groove depth at a radius of 58 mm from the center is preferably 10 to 20 nm deeper than at a radius of 23 mm.

Alternatively, regarding the groove depth obtained by measuring the optical groove shape, the value of the groove depth at a position y 27000 tracks outside the position x with respect to the value of the groove depth at a certain position x exceeds 1.00 times. It is preferably 1.07 times or less, more preferably 1.02 times or more and 1.07 times or less. In the case of the groove depth measured by the AFM, the value of the groove depth at the outermost circumference is more than 1.00 times and equal to or less than 1.13 times the value of the groove depth at the innermost circumference. More preferably, it is 1.03 times or more and 1.13 times or less.

In order to ensure uniformity of recording characteristics such as sensitivity in the medium plane, the groove width (half width) of the guide groove of the substrate measured by measuring the optical groove shape is 0.28 μm to 0.31 μm, more preferably 0.29 μm. It is preferably from μm to 0.31 μm. Groove width is 0.
If it is less than 28 μm, the groove width is too narrow, and the jitter margin of the recording layer is narrow, so that good characteristics may not be obtained. On the other hand, if it exceeds 0.31 μm, it is too wide, so that the distortion in the longitudinal direction of the reproduction waveform of the recording signal is too large, and good jitter characteristics may not be obtained.

Further, the groove width at a radius of 45 mm from the center is 0.003 to 0.010 more than at a radius of 25 mm.
It is preferably μm wide. If the increase in the groove width is less than 0.003 μm, it is difficult to obtain uniformity of sensitivity toward the outer periphery. On the other hand, when the thickness exceeds 0.01 μm, the width becomes too wide, and the uniformity of jitter characteristics may be impaired. Also, 27000 from the position x with respect to the value of the groove width at a certain position x
The value of the groove width at the position y outside the track is preferably more than 1.00 and not more than 1.04, and 1.01 or less.
It is more preferable that the value is not less than twice and not more than 1.04 times.

The uniformity of push-pull is determined by DV
According to the D-R standard (ver.1.0), it is 15% or less in the entire user zone, but in the present invention, as a stricter standard, a preferable range is 10% or less in a region having a radius of 23 to 57 mm from the center. . Regarding the recording characteristics, as a characteristic that can sufficiently cope with drives and recorders of various design concepts, the jitter from 23 to 57.5 mm is 8.4% or less, and the asymmetry (a
Symmetry) was set to 5% or less, and the PI error (maximum value) was set to 100 or less.

As a method of increasing the depth of the guide groove of the substrate toward the outer periphery as in the present invention, for example, in the step of forming the guide groove on the transparent resin substrate by a photoresist method, a glass master is used. The thickness of the photoresist to be spin-coated is changed (increased) from the inner circumference to the outer circumference. Further, as a method of increasing the groove width toward the outer periphery, there is a method of changing the power of laser light from the inner periphery to the outer periphery when exposing the photoresist layer applied on the glass master.

The groove depth and groove width preferably change (increase) at a substantially constant rate from the innermost circumference to the outermost circumference of the medium from the viewpoint of ease of stamper manufacture, but the rate of increase is not constant. Alternatively, it may be from an inner circumference to an outer circumference to some extent. For example, the groove depth or groove width is substantially constant from the inner peripheral portion to the middle peripheral portion, and the groove depth or the groove width may be increased only from the middle peripheral portion to the outer peripheral portion. Further, the groove depth or groove width may be gradually increased from the inner peripheral portion to the middle peripheral portion, and the groove depth or the groove width may be substantially constant from the middle peripheral portion to the outer peripheral portion.

The latter example will be described more specifically. In the guide groove forming region on the substrate, the innermost circumference is position a, a portion closer to the outer circumference by 63% in the radial direction from position a is position b, and the outermost circumference is position c. As for the groove depth by the optical groove shape measurement, the value at position b is preferably 1.00 to 1.07 times the value at position a, and 1.02 to 1.07.
The value at position c is preferably 0.95 to 1.01 times the value at position b. When the value at position b is 1.00 times the value at position a (ie, the same depth), the value at position c with respect to the value at position b is more than 1.00 times and preferably not more than 1.01 times. .

This is because the transfer is excessive and the shape of the wall surface of the guide groove becomes irregular, so that the recording characteristics deteriorate. In the optical recording medium of the present invention, preformat information such as address information is formed as land prepits (LPP) on the substrate. For example, in the case of a DVD-R for consumer use, recording is often performed by a drive or recorder equipped with an inexpensive laser having a longer wavelength than that of a conventional DVD-R. The recording characteristics tend to be easily affected by the shape and size of the land pre-pits because the recording characteristics are low. In order to suppress the influence on the recording characteristics, the maximum length in the direction parallel to the guide groove at the bottom of the land pre-pit, which is shown as l _{LLP in} FIG. 3 or 4, must be 0.20 μm to 0.31 μm. No. If it is less than 0.20 μm, the land pre-pits are too small to read the address information correctly, and the moving image may not be recorded correctly. On the other hand, if the thickness exceeds 0.31 μm, the recording signal quality is too large to affect the recording characteristics, and the quality of the recording signal is liable to deteriorate, such as deterioration of jitter and error.

As shown in FIG. 3 or FIG. 4, the shape of the land prepit is substantially circular (including an elliptical shape), saddle shape,
There may be a bridge-like structure in which one side is widened. Among them, a substantially circular shape that fits inside the land width of the substrate as shown in FIGS. 3A to 3C is preferable. The land width of the substrate is preferably 1.3 to 1.7 times the groove width, from the viewpoints of securing a sufficient land pre-pit signal intensity and reducing the influence on the recording portion.

The width of the land of the substrate is equal to the width of the guide groove of the substrate.
If it is less than three times, the groove width is relatively too wide, and good recording tends to be difficult. If it exceeds 1.7 times, the groove width is too narrow, so that the land pudding pits easily enter the field of view of the beam, which may adversely affect reproduction and recording. It is more preferable that the bottom of the land prepit and the bottom of the guide groove of the substrate are on the same plane.

The recording layer is usually obtained by spin-coating a solution obtained by dissolving an organic dye and various additives as necessary in a solvent on a transparent substrate. The solvent is preferably a solvent which dissolves an organic dye and various additives at a high concentration and does not erode the transparent substrate. For example, a fluorinated alcohol having a boiling point of 100 to 150 ° C. and a carbon number of 3 or more, ie, 1H , 1H, 3H-tetrafluoropropanol, 1H, 1H, 5H-octafluoropentanol, 1H, 1H, 3H-hexafluorobutanol and the like are preferably used. When the boiling point is less than 100 ° C., the solvent evaporates rapidly during spin coating, so that the coating solution does not reach the outer peripheral side from the radius of 40 mm of the medium, and the film thickness distribution in the radial direction tends to be large. Characteristics may not be obtained. In addition, the boiling point is 150 ° C.
When it exceeds, the evaporation takes time and the solvent tends to remain in the film, so that good recording jitter may not be obtained.

The refractive index n of the recording layer is usually 2.0 to 3.0,
Preferably it is 2.3 to 2.6, and the extinction coefficient k is 0.0.
3 to 0.10 is preferred. In particular, as in the present invention, when a medium having better recording sensitivity than the conventional DVD-R is used, k is 0.08 to 0.10 at the wavelength of the recording / reproducing light, which is relatively large. Dyes are preferred. The measurement of n and k of the recording layer in the present invention can be performed by the following method. A recording layer forming solution containing an organic dye is placed on a mirror replica so as to cover approximately half of the surface of the board, spin-coated, a reflective layer is sputtered on a part of this recording layer, and a step from the uncoated part is formed. Was measured with a three-dimensional surface roughness meter (ZYGO: Maxim5800, manufactured by Canon Inc.) to determine the film thickness, and an automatic wavelength scanning ellipsometer (MEL-
After measuring multiple incident angles with a 30S type), n and k with good convergence are determined with reference to the above-mentioned film thickness, and the optical constants n and k for obtaining them are determined.
And

In a consumer DVD-R, the groove depth of the recording layer in an unrecorded state is 60 to 75% of the groove depth of the substrate at the same position, and the film thickness of the recording layer is smaller than that of the land. It is preferable that the thickness be 10 to 50 nm in the part and 80 to 105 nm in the groove. Since the recording / reproducing light wavelength of the consumer DVD-R has been increased from about 640 nm used for the conventional DVD-R to about 660-670 nm,
The difference in reflectivity (radial contrast) between the land and the groove became smaller. Therefore, in order to obtain a sufficient radial contrast for stable tracking, it is preferable that the groove depth of the recording layer is larger.

The inclination angle of the wall surface of the groove of the recording layer viewed from an SEM image of the same size in the vertical and horizontal directions is preferably 10 ° to 40 °. As shown in FIG. 2, the “inclination angle of the wall surface of the groove of the recording layer” is defined by an extension of the wall surface (side surface) of the groove of the recording layer and the surface of the recording layer laminated on the land portion of the substrate. The angles θ _abs and θ ′ _abs are meant. When the angle is less than 10 °, the height difference between the land and the land corresponding to the guide groove and the land of the substrate, which is generated on the surface of the recording layer, is too small to make a distinction. May not be possible. On the other hand, when the angle exceeds 40 °, the thickness of the groove portion of the recording layer becomes small, and a sufficient recording modulation degree may not be obtained. The inclination angle of the wall surface of the groove of the recording layer is more preferably 20 ° to 30 °.

The measurement of θ _abs and θ ′ _abs is performed as follows. First, the optical recording medium was subjected to ion etching (the present inventors used “Hitachi FB-2000A” manufactured by Hitachi, Ltd.), and the cross section of the medium exposed to the surface was sampled at a sample angle of 50 °.
At an angle of 1 °, the interface between the recording layer and the reflective layer was scaled by the SEM (the present inventors used “Hitachi S-900 type” manufactured by Hitachi, Ltd.) at 1 × length (the present inventors 100,000 times). Observe and θ _abs
And θ ′ _abs were measured.

As an example of the organic dye, any skeleton dye such as a cyanine-based, phthalocyanine-based, or gold-containing azo dye may be used as long as the dye satisfies the above-mentioned basic physical property conditions, but a metal-containing azo dye is particularly preferable. In order to reduce the amount of heat generated during the decomposition of the dye or to improve the recording sensitivity, the recording layer contains a sublimable compound or a compound that absorbs heat during the decomposition in an amount of about 3 to 20% by weight of the dye. You may. Examples of such compounds include low molecular weight cyanine dyes, thiophene compounds, and azo dyes (not metal chelated).

The reflective layer is preferably a metal film that efficiently reflects the laser light transmitted through the recording layer. The wavelength region of the recording / reproducing light used for ordinary optical recording, that is, 400 nm
In order to prevent the reflectance from decreasing at 700 nm to 700 nm, the refractive index of light in the wavelength range of recording / reproducing wavelength ± 5 nm must be 0.1 to 700 nm.
It is preferable that the extinction coefficient k is 1.5 to 1.5. Particularly, when the refractive index is 0.1 to 0.2 and the extinction coefficient is 3 to 5, it is more preferable because a high reflectance can be obtained. But,
In the case of aiming for even higher linear velocity recording, it is considered necessary to consider the influence of the reflectance of the metal reflection layer and the thermal conductivity.

When the metal reflective layer is sputtered, it is necessary to minimize the amount of interfacial oxygen. This is because there are a large number of dyes whose behavior during thermal decomposition is greatly changed by the presence of oxygen. The material of the metal reflection layer is preferably a silver alloy containing 0.1 to 1 at% of a gold or platinum group element, or an aluminum alloy or a copper alloy. Since the sputtered film of such an alloy target has a greater film strength (a property of suppressing an excessive deformation because of a force opposing an increase in internal pressure during recording) than silver, a recording power margin, It is preferable because environmental resistance is ensured.

The appropriate thickness of the reflective layer is 40 nm to 200 nm. Also, in sputtered films of silver, aluminum, copper and many silver, aluminum, and copper alloys, grain boundaries of several tens of nanometers may be generated in a high-temperature and high-humidity environment test, or grain growth may be observed, It has been found that this has a bad influence on the characteristics of the archival (life characteristics of the recording section). As means for suppressing the generation and growth of the grain boundaries, the ultimate vacuum degree at the time of sputtering should be improved by 10 times or more as compared with the conventional method, or it should enter between metal atoms such as H, B, C and N. As a fourth additive element, there may be added an atom which forms a solid solution that has a low mobility and easily moves, such as Co, Mn, Cr, Gd, Ti, and Mg. The grain boundary has a sectional shape SE.
M or the surface obtained by breaking the medium and peeling off the metal reflective layer at the interface with the recording layer can be observed by SEM.

In the optical recording medium of the present invention, a protective layer is laminated on the reflective layer in order to prevent the formation of holes in the metal reflective layer in the recording portion and to suppress the asymmetry of deformation. Is better. It is preferable that the protective layer is formed of an ultraviolet curable resin. In addition, usually, the thickness of the protective layer is set to 1 μm or more, preferably 3 μm or more so that suppression of curing by oxygen or the like does not occur.

Furthermore, an optical recording medium may be obtained by laminating the above-described substrate having at least a recording layer and a reflective layer on a substrate and another substrate or a substrate having an arbitrary layer on the substrate. . For bonding, use a cationic delayed-curing type ultraviolet curable resin or a viscosity of 30 to 8
It is preferable to use an adhesive which is a radical type instant curing type ultraviolet curing resin of 00 cps. The thickness of the adhesive layer formed on the adhesive is not particularly limited, but is usually about 10 to 20 μm. The “substrate having an arbitrary layer” to be bonded may be the above-described substrate provided with at least a recording layer and a reflective layer on the substrate (that is, the same substrate), or may be aluminum or the like on the substrate. A medium in which a protective layer is laminated on a metal reflection layer may be used, but the warpage of both surfaces is adjusted so that the tilt angle in the tangential direction to the track direction of the recording / reproducing surface after bonding is 0.3 degrees or less. It is preferable to combine

Also, centering at the time of bonding and
It is necessary to pay sufficient attention to the eccentricity of the substrate itself, and it is preferable that the eccentricity after bonding is sufficiently small so as to be 20 μm or less. If the value exceeds the above range, a good jitter value may not be obtained unless a pickup (a drive having a tilt servo mechanism) that performs extremely high-precision adjustment is used. As a result, the error rate becomes poor. There is a risk.

Further, it is preferable that the surface deflection acceleration of the bonded recording surface is ± 5 m / s ² or less. If it is out of this range, there is a possibility that a sufficient characteristic margin cannot be obtained in a consumer drive or recorder. In particular, when using a device in which the tilt servo mechanism during recording is simplified,
It is not possible to follow a rapid change in the plane runout acceleration, and a local distortion occurs in the recording waveform, which may result in an increase in jitter or error. Surface run-out acceleration increases due to dust on the protective layer and adhesive layer of the medium, unevenness in the thickness of the protective layer and adhesive layer due to the incorporation of bubbles, and the degree of engagement of the resin with the mold during molding of the resin substrate. I do.

As an adhesive, a viscosity of 30 cps to 300 c
When a radical type instant curing type ultraviolet curable resin of ps is used and bonded so that the maximum length of the void in the adhesive layer after the adhesive is cured is 10 μm or less, the bonding is performed to improve impact resistance. It is preferable in terms of strength. This is preferable when, for example, information related to the production of a medium is formed as an optical barcode by a laser. In particular,
When the optical barcode is formed by irradiating the above laser beam after bonding, if a gap having a maximum length exceeding 10 μm is present in the adhesive layer, the structure of the adhesive layer appears on the barcode portion. Signal quality may be degraded.

[0042]

[Example 1]

<Production Example of Optical Recording Medium> On an injection-molded polycarbonate substrate having a thickness of 0.59 to 0.61 mm, the track pitch is 0.73 to 0.74 μm, and the groove depth by the optical groove shape measurement is radius 22. To a groove depth of 145 nm, 153 nm, and 152 nm (25 mm, 45 mm, and 56 mm, respectively) from the center.
the difference between the groove depths at 8 mm and 45 mm is 8 nm)
The groove width also increases continuously from 22 to 56 mm like the groove width, and the groove width at 25 mm, 45 mm, and 56 mm is 0.293 μm, 0.298 μm, and 0.305 μm.
(The difference in groove width between 25mm and 45mm is 0.005μ
m) was formed.

On this substrate, 1.7 w of a metal-containing azo dye was placed.
A t% octafluoropentanol solution was spin-coated and dried at 90 ° C. for 30 minutes. In this state, the absorption maximum (maximum absorption wavelength) of the absorption spectrum (measured with an ultraviolet-visible spectrophotometer) of the recording layer was 598 nm. A silver alloy containing 97 atom% or more of Ag is sputtered on the recording layer to form a reflective layer, and an ultraviolet curable resin (Dainippon Ink SD-318) is spin-coated thereon to a thickness of 6 μm. A protective layer was formed.

On the protective layer, a cationic delay type ultraviolet curable resin is applied with a mesh (300) screen, and the metal surface of a dummy substrate (in which an injection molded polycarbonate substrate is provided with a metal film) is bonded. An optical recording medium was formed. <Evaluation Example of Optical Recording Medium> Wavelength 567 nm (NA = 0.6
Using the evaluator equipped with the semiconductor laser of (0) (Pulstec “DDU-1000”), the amplitude of the push-pull signal (the difference signal of the pickup between the groove and the land crossing signal) of the medium is measured using the groove and land. Was divided by the average value of the sum signal traversing the
At 6 mm and 57 mm, 0.38, 0.41,
0.39 and 0.37, and the distribution ((maximum value−minimum value) / (maximum value + minimum value)) was as good as 5.1%.

(Note that in the DVD-R standard version 1.0,
It is stated that the distribution does not exceed 15% in the recordable area. In the present invention, since the evaluation is performed at a radius of 23 to 57 mm, it is preferable that the value does not exceed 10%. Also, using an evaluator equipped with a semiconductor laser having a wavelength of 657 nm (NA = 0.65) as the medium, the recording power was fixed at 9.6 mw, and the recording linear velocity was 3.5 m / s (1 × speed). -1
Six-modulation EFM + signals were recorded from 23 to 57.5 mm.
When the medium after recording was reproduced with a ROM reproduction inspection machine (“LM220A” manufactured by Shibasoku Co., Ltd.) equipped with a semiconductor laser having a wavelength of 647 nm (NA = 0.60), the medium was 23 mm
Asymmetry at 7.5mm

[0046]

(Equation 1)

Are 10.3% and 10.1%, respectively.
The difference was as high as 0.2%, and the sensitivity was high. (In consideration of the drive margin, 23m
The difference in asymmetry between m and 57.5 mm is preferably 5% or less. ) Jitter and PI error were also good. The groove depth of the recording layer of this medium measured by AFM was 102 nm, 105 nm, 103 nm, and 107 nm at radii of 23 mm, 40 mm, 55 mm, and 58 mm, respectively, and the groove depth of the substrate at the same position (158 nm, 16
5%, 168 nm and 171 nm), 6%
4%, 61%, and 63%.

When the cross section of this medium was cut out by ion etching and observed by SEM, the inclination angle of the groove wall of the recording layer in an image of the same length and width obtained at a sample inclination angle of 50 degrees was 20 to 30 degrees. Met. The shape of the land pre-pit was (c) in FIG. 3 from the inner circumference to the middle circumference, and (a) in the outermost circumference, and the maximum length of the land pre-pit was 0.23 μm.

The calorific value of the organic dye used in the recording layer of this optical recording medium in DSC measurement in nitrogen was 490 kJ / mol, and the calorific value in differential thermal balance measurement in nitrogen was 15.2 μV / mg. Met. When the radius of the recording layer is 40 mm, the land thickness is 30 nm and the groove thickness is 9
It was 5 nm.

The surface run-out acceleration of the medium is from 23 mm to 5
It was 2 m / s ² or less up to 8.3 mm. Tables 1 and 2 show the above evaluation results. Examples 2 to 5 and Comparative Examples 1 to 4 Optical recording media were produced and obtained in the same manner as in Example 1 except that substrates having the groove depths and widths shown in Tables 1 and 2 were used. The media was evaluated. The recording and reproducing conditions are the same as in the first embodiment. The results are shown in Tables 1 and 2.

[0051]

[Table 1]

[0052]

[Table 2]

[0053]

According to the present invention, a drive and a recorder are provided.
It is possible to provide a consumer DVD-R recording medium having a wide margin and good recording characteristics even for high-speed recording.

[Brief description of the drawings]

FIG. 1 illustrates an example of the configuration of an optical recording medium according to the present invention.
It is a principal part expanded sectional view.

FIG. 2 is an enlarged cross-sectional view of a main part for explaining a film thickness, an angle, and the like in the optical recording medium.

FIG. 3 is a diagram illustrating an example of a shape of a land prepit and a maximum length in the optical recording medium.

FIG. 4 is a diagram illustrating an example of a shape of a land prepit and a maximum length in the optical recording medium.

FIG. 5 is a diagram showing an emission pulse corresponding to a 5T mark length used for recording on the optical recording medium.

FIG. 6 is a view for explaining a groove depth by optical groove shape measurement and measurement using AFM in the same optical recording medium.

[Explanation of symbols]

1 substrate 2 recording layer 3 reflecting layer 4 protective layer 5 guide groove (groove) 6 land portion 7 land prepit W _g groove width (half width) of the guide groove of the substrate W _l land width P track pitch d of the guide groove of the substrate by the groove depth d _sub1 optical groove shape measuring of the guide groove of the _sub substrate, is observed at the groove of the guide groove of the substrate depth d _sub2 AFM, the groove depth of the groove depth d _abs recording layer of the guide groove of the substrate D _g Thickness of the groove of the recording layer D _l Thickness of the land of the recording layer θ _abs , θ ′ _Abs Angle of inclination of the wall of the groove of the recording layer l At the bottom of the _LPP land _prepit , in the direction parallel to the guide groove Maximum length

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshihiro Noda 1000 Kamoshita-cho, Aoba-ku, Yokohama-shi, Kanagawa Prefecture Inside Mitsubishi Chemical Corporation (72) Inventor Keiichi Ota 3-10 Kuroshiki-shi, Okayama Prefecture Mitsubishi Chemical Corporation Inside Mitsubishi Chemical Corporation (72) Inventor Shuji Takeshima 1000 Kamoshita-cho, Aoba-ku, Yokohama-shi, Kanagawa Prefecture F-term in Mitsubishi Chemical Corporation 5D029 WB15 WB19 WC01 WD30

Claims (4)

[Claims] 1. A disk-shaped substrate on which a guide groove is formed,
An optical recording medium comprising a recording layer and a reflective layer containing an organic dye, wherein the groove depth and / or groove width of the guide groove is increased from the inner periphery to the outer periphery of the substrate. Medium. 2. The method according to claim 1, wherein the depth of the guide groove of the substrate in the optical groove shape measurement is 140 to 155 nm, and the groove depth at a radius of 45 mm from the center is 5 to 9 nm deeper than at a radius of 25 mm. 2. The optical recording medium according to 1. 3. The groove depth of the guide groove of the substrate as observed by an atomic force microscope is 150 to 180 nm, and the groove depth at a radius of 58 mm from the center is 5 to 20 nm deeper than at a radius of 23 mm. The optical recording medium according to claim 1, wherein 4. The groove width of an optical groove shape measurement of a guide groove of a substrate is 0.28 to 0.31 μm, and the radius is 45 m from the center.
groove width at m = 0.003 than at radius 25 mm
The optical recording medium according to any one of claims 1 to 3, wherein the optical recording medium is wider by 0.010 µm.