JPH08129780A - Optical recording medium - Google Patents

Abstract

PURPOSE: To obtain a hybrid disk having signal characteristics satisfying orange book (CD-R) standards by forming dyestuff films of specific shapes on prepit and pregrooves. CONSTITUTION: A disk-shaped substrate 1 formed with the prepits 6 and the pregrooves 5 is provided thereon with a dyestuff layer 2, a reflection layer 3 and a protective layer 4. The prepits 6 have a half-power band width of 0.4 to O.7μm and depth of 200 to 400nm and the difference in the optical path length between the prepit parts 6 and the prepits 6 is specified to >=0.20 to <=0.4λ(where λ is the wavelength of a laser beam for reproduction). The pregrooves 5 have a half-power band width of 0.3 to 0.6μm and depth of 170 to 250nm and the difference in the optical path length between the pregrooves 5 and the pregrooves 5 is specified to <=0.15λ.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, and more particularly to an optical recording medium capable of recording and reproducing information by laser light having a prepit portion and a pregroove portion provided on a substrate.

[0002]

2. Description of the Related Art As an optical recording medium having a reflective layer on a substrate, a recordable or recordable CD (CD-R) corresponding to the compact disc (hereinafter abbreviated as CD) standard has been proposed [eg Nikkei Electronics. , No. 46
5, P.I. 107, January 23, 1989]. As shown in FIG. 1, this optical recording medium has a recording layer 2, a reflective layer 3 and a protective layer 4 formed in this order on a substrate 1. When the recording layer of this optical recording medium is irradiated with a laser beam such as a semiconductor laser with high power, the recording layer undergoes a physical or chemical change to record information in the form of pits. Information on the pits can be reproduced by irradiating the formed pits with low-power laser light and detecting the reflected light.
A wavelength of 770 is generally used for recording / reproduction of such an optical recording medium.
A near-infrared semiconductor laser of 830 nm is used for the Red Book (CD) and Yellow Book (CD-R).
OM), Orange Book (CD-R), and the like, and therefore has the characteristic of being compatible with CD players and CD-ROM players.

Dyes used in commercially available CD-Rs are roughly classified into phthalocyanine dyes and cyanine dyes. It is known that these dyes have different optical characteristics that are important for the signal characteristics of the medium. That is, the refractive index of a dye used in a commercially available CD player or the like at a wavelength of 770 to 830 nm for reproducing laser light is 2.0 to 2.3 for a phthalocyanine dye, and 2.8 for a cyanine dye. The value of ˜2.9 is about 0.5, which is lower for the phthalocyanine dye. The refractive index of the dye is the most important parameter in designing the medium. In particular, the two dyes affect the optimum conditions in the medium design (for example, the pit and groove shape of the substrate, the coating of the dye, and the like) because they affect the reflectance and the modulation of the signal. The shape of the film) differs greatly. That is, since the cyanine dye has a higher refractive index than the phthalocyanine dye, the reflectance is high, and the depths of the pits and the grooves can be made shallow, so that the substrate can be easily molded. On the other hand, the phthalocyanine dye has an advantage over the cyanine dye in that the recording time can be shortened because it has excellent durability against light, heat, humidity, etc. and excellent high-speed recording characteristics. .

Recently, as a new type of CD-R, a combination of a read-only area (ROM area) such as the above-mentioned CD or CD-ROM and a recordable or recordable area (RAM area) such as the above-mentioned CD-R is used. Recording media have been proposed. This optical recording medium is called a hybrid disc in the Orange Book, which is the standard for CD-R, and
In the M area, pre-pits are provided on the substrate like a music CD or CD-ROM, and in the RAM area the CD-R
As described above, the pregroove is formed on the substrate.

As a method of forming the ROM area of the hybrid disk, there are the following two methods. That is, 1. A method in which an optical recording medium that can record on the entire surface is prepared, and the manufacturer records each piece of information as a ROM area using a recording device and provides it to the user.

2. ROM area is a conventional CD or CD-R
A method in which pre-pits are formed on the substrate in advance at the stage of substrate molding like OM and the remaining area is used as a recordable area (RAM area).

Considering the mass productivity of media, it is considered that the second method of forming prepits on the substrate in advance is superior. Various proposals have been made for an optical recording medium in which a ROM area is formed by such a method, but there are two types according to the structure of the medium.

One is that no recording layer is provided in the ROM area,
This is a medium in which a recording layer is formed only in the RAM area.
The method of applying only the RAM area in this way is presumed to be due to the following reason. That is, normally, when a dye is applied by a spin coating method onto a substrate on which prepits or pregrooves are formed, a phenomenon occurs in which the prepits or pregrooves are filled with the dye. In the case of the ROM area, the pre-pits formed in advance are the same as those of the conventional CD or CD-ROM, and if the direct reflection layer is formed, a signal satisfying the CD standard can be obtained. If a reflective layer is provided from the above, the pre-pit shape will change, and the Orange Book (CD-R)
It becomes impossible to satisfy the standard. Therefore, in the ROM area, the same pits as those of a normal CD are used, so that the dye layer is not formed in the pit portion.
Such methods are disclosed in JP-A-2-195540, JP-A-3-225638, JP-A-4-143938 and JP-A-4.
-167238, JP-A-4-172635, and JP-A-4-172635
176033, JP-A-4-245042, JP-A-4-4-2
55931, JP-A-4-3566743, JP-A-4-37
2735, JP-A-5-67349, and JP-A-5-1592.
There are 95 and so on.

However, the above method has the following drawbacks. The recording layer is usually formed by the spin coating method, but in this case, it is impossible to accurately paint the boundary between the ROM area and the RAM area. For this reason, some of the ROM area may be coated with dye, or R
It is difficult to form the area with good reproducibility because a recording / reproduction impossible area occurs at the boundary part because the dye is not applied to a part of the AM area. Further, the existence of such a recording / reproduction impossible area causes a decrease in storage capacity. CD-R
In the Orange Book, which is the standard of the above, a medium (called a hybrid disk) in which the ROM area and the RAM area already exist is standardized. In this method, the time of the ROM area and the RAM area described in the Orange Book is It is impossible to meet the standard of making information continuous.

Therefore, a method has been proposed in which the recording / reproducing area at the boundary between the ROM area and the RAM area is eliminated to obtain a signal characteristic satisfying the Orange Book standard.
The method is to provide a recording layer in both the ROM area and the RAM area as shown in FIG. 1, and by controlling the shapes of the prepit portion and the pregroove portion and the dye film thicknesses thereof, the ROM area and the RAM area. CD-
Signal characteristics satisfying the Orange Book standard, which is the standard for R, can be obtained.

The above methods include the following. That is, JP-A-3-241538 and JP-A-4-14653.
6, JP-A-4-146537, JP-A-4-162222
7, JP-A-4-177636, JP-A-4-24301
9, JP-A-4-289535, JP-A-4-28953
6, JP-A-4-302833, JP-A-4-33522
3, JP-A-5-12680, JP-A-5-36087, JP-A-5-67355, JP-A-4-286734, JP-A-4-289532, JP-A-4-289534, JP-A-5.
-73964, JP-A-5-114178, JP-A5-1
59377 and JP-A-5-159878.

In these methods, the ROM area and the RAM are defined by defining the shapes of the prepit portion and the pregroove portion and the shape of each dye film when the dye is applied.
The signal characteristics of the area satisfy the Orange Book standard.

For example, according to Japanese Patent Laid-Open No. 4-146537, the half width of the prepits is 0.2 to 1.4 μm and the depth is 150 to 400 nm.
In addition, as shown in the following formula [Equation 1], the total optical path length between the substrate and the dye layer at the bottom of the prepit is λ / 8 than the total optical path length between the substrate and the dye layer at the prepit portion.
It is described that the signal characteristics in the ROM area satisfy the standard by making the length longer (where λ is the wavelength of the reproducing laser light). However, when a phthalocyanine dye having a lower refractive index than the cyanine dye is used in the recording layer, under this condition, the optical path length difference between the pre-pit bottom and the pre-pit is too small to obtain a modulation degree that satisfies the Orange Book standard. There is.

[0014]

[Equation 1] Prepit condition Half width W_p= 0.2 to 1.4 (μm) depth d_p= 150-400 (nm) Optical path length difference (L_p) L_p ≧ λ / 8 (= 0.125λ) [however, L_p= N_sd_p+ N_d(T_pl-T_p) = N_sd
_p+ N_d(Δ_p-D_p), N_sAnd n_dIs it
The wavelength (λ) of the laser light for reproduction of the substrate and dye layer respectively
Refractive index, d_pAnd d_gAre the pre-pit and
Regroove depth, t_plAnd t_pIs the pre-pit
The film thickness of the dye layer at the space and the bottom of the prepit, t_glAnd t_g
Is the color between the pregroove and the bottom of the pregroove.
Thickness of elementary layer, δ_pAt the interface between the dye layer and the reflective layer
Depth at bottom of pit (δ_p= D _p+ T_pl-T_p)so
is there. ]

Regarding the pregroove portion, the half width of the pregroove is 0.2 to 1.4 μm and the depth is 170 to.
The depth of the prepit is set to 200 nm, and the depth of the prepit is expressed by the optical path length rather than the depth of the pregroove as shown in the following equation (2). Λ / 8 (= 0.125λ) (where λ is the reproducing laser beam). Wavelength)) and the total optical path length between the substrate and the dye layer at the bottom of the prepit is λ / 8 (=
0.125λ) (where λ is the wavelength of the reproducing laser beam) or more, it is described that signal characteristics satisfying the Orange Book (CD-R) standard can be obtained. However, when a phthalocyanine dye is used. As with the pre-pit portion, there are cases where the signal characteristics satisfying the standard cannot be obtained.

[0016]

[Formula 2] Pregroove condition Half width W_g= 0.2 to 1.4 (μm) depth d_g= 170 to 200 (nm) Difference between prepit and pregroove depth (optical path length) n_s(D_p-D_g) ≧ λ / 8 (= 0.125λ) Optical path length difference (L_p) L_g≧ λ / 8 (= 0.125λ) [however, L_g= N_sd_g+ N_d(T_gl-T_g) = N_sd
_g+ N_d(Δ_g-D_g), N_sAnd n_dIs it
The wavelength (λ) of the laser light for reproduction of the substrate and dye layer respectively
Refractive index, d_pAnd d_gAre the pre-pit and
Regroove depth, t_glAnd t_gIs the pre-pit
The film thickness of the dye layer at the space and the bottom of the prepit, t_glAnd t_g
Is the color between the pregroove and the bottom of the pregroove.
Thickness of elementary layer, δ_gAt the interface between the dye layer and the reflective layer
Depth at bottom of pit (δ_g= D _g+ T_gl-T_g)so
is there. According to Japanese Patent Laid-Open No. 4-289532, pre-pits and pre-pits
The following conditions [Equation 3] and
Wow,

[0017]

[Formula 3] Condition of pre-pit portion 0.3λ ≦ | 2 {n_sd_p-N_d(D_p+ T_pl−
t_p)} | <0.5λ Pre-groove condition | 2 {n_sd_g-N_d(D_g+ T_gl-T_g)} | <0.3λ [where n_sAnd n_dRegenerate substrate and dye layer respectively
Refractive Index at Wavelength (λ) of Laser Light for Use, d_pAnd d_g
Is the depth of the pre-pit and the pre-groove, t_plOver
And t_pAre between the pre-pit and the bottom of the pre-pit, respectively.
Film thickness of dye layer, t _glAnd t_gBetween pregrooves
And the thickness of the dye layer at the bottom of the pre-groove. ] Full
If added, a good reproduced signal with a large degree of modulation can be obtained.
it can. However, when phthalocyanine dye is used,
In this case, under these conditions, the pit lower part of the pre-pit part and the pit
The difference in optical path length between parts is too small to meet the Orange Book standard.
In some cases, sufficient recording / reproducing characteristics cannot be obtained. further,
According to Japanese Patent Laid-Open No. 4-335223, [Equation 4],

[0018]

[Equation 4] Pre-pit condition 0.15λ ≦ L_p≦ 0.24λ and pregroove condition 0.02λ ≦ L_g≤0.08λ [However, L_p= N_sd_p+ N_d(T_pl-T_p) = N_sd
_p+ N_d(Δ_p-D_p), L_g= N_s× d_g+ N_d(T
_gl-T_g) = N_sd_g+ N_d(Δ_g-D_g),
n_sAnd n_dIs the laser for reproducing the substrate and dye layer, respectively
Refractive index at the wavelength of light (λ), d_pAnd d_gEach
Depth of pre-pit and pre-groove, t _plAnd t_pIs
Of the dye layer between the pre-pits and the bottom of the pre-pits
Film thickness, t_glAnd t_gBetween the pregroove and the
The thickness of the dye layer at the bottom of the regroove, δ _pAnd δ_gEach
At the interface between the dye layer and the reflective layer.
Depth at bottom of regroove (δ_p= D_p+ T_pl−
t_p, Δ_g= D_g+ T_gl-T_g). ] Please
A good reproduction signal with a large degree of modulation can be obtained.
However, when a phthalocyanine dye is used, this
Under the conditions, the optical path length difference in the pit is too small,
If the modulation level is too small to meet the Orange Book standard,
There is a match.

[0019]

An object of the present invention is to provide an optical recording medium in which a dye layer, a reflective layer and a protective layer are provided in this order on a disk-shaped substrate on which prepits and pregrooves are formed, A phthalocyanine dye is used in the dye layer by making the pre-pits deep enough so that the difference in the optical path length between the pit and the pit and the difference in the optical path between the pre-groove and the group are within a specific range. Even if you were there, the Orange Book (CD-
It was found that an optical recording medium having good signal characteristics satisfying the R) standard can be provided, and the present invention was completed.

[0020]

Means for Solving the Problems The inventors of the present invention have made extensive studies to solve the above problems, and as a result, have proposed the present invention. That is, this problem is solved by the following invention. That is, the present invention is an optical recording medium in which a dye layer, a reflective layer, and a protective layer are provided in this order on a disk-shaped substrate on which prepits and pregrooves are formed, and the prepits have a half-value width of 0.4. ~ 0.7μm, depth 2
Has a length of 0.00 to 400 nm, and a difference in optical path length between the pit portion and the pit portion is 0.20λ (where λ is the wavelength of the reproducing laser beam) or more and 0.40λ or less, and the pregroove is half Price range 0.3-0.6 μm, depth 170-25
An optical recording medium having an optical path length of 0 nm and a difference in optical path length between the groove portion and the groove portion is 0.15λ (where λ is the wavelength of the reproducing laser light) or less. In particular, the present invention is directed to an optical recording medium in which the dye layer is made of a phthalocyanine dye, and in particular, an optical recording medium in which the reflective layer is made of a metal containing Au as a main component. According to the present invention, it is possible to provide a hybrid disc having signal characteristics that satisfy the Orange Book standard.

The specific structure of the present invention will be described below. The optical recording medium of the present invention has a structure in which a recording layer and a reflective layer are formed in this order on a substrate on which spiral prepits and pregroove tracks are formed. In FIG. 1, the right V-shaped groove 5 is a pre-groove, and the left substantially V-shaped groove 6 is a pre-pit. That is, in the above optical recording medium, a read-only ROM area in which pre-pits 6 are formed as recording signals is provided on the inner peripheral side substrate, and a write-once RAM area composed of pre-grooves 5 is provided on the outer peripheral side substrate. There is. ROM area and RA
Two or more M areas may be provided as needed, and the ROM area may be on the outer peripheral side and the RAM area may be on the inner peripheral side. It is also possible to perform wobbling on the prepit and pregroove tracks and use the wobbling cycle at that time as absolute time data.

The prepits and pregrooves according to the present invention are characterized by having a specific shape. That is, the half width of the pre-pit (1 / the depth of the pit)
Width of the pit at a depth of 2) is 0.4 to 0.7 μm,
The thickness is preferably 0.45 to 0.65 μm, and particularly preferably 0.5 to 0.6 μm. Further, the depth of the prepit is as deep as 200 to 400 nm, preferably 250 to 350 nm, and particularly preferably 280 to 32.
It is 0 nm. If the full width at half maximum or the depth of the pre-pit is out of the above range, the modulation degree or the servo signal becomes small and the Orange Book standard may not be satisfied.

On the other hand, the half-value width of the pre-groove (the width of the pit at a depth of 1/2 of the pit depth) is 0.3 to 0.6.
μm, preferably 0.4 to 0.6 μm, particularly preferably 0.45 to 0.55 μm, and the depth of the pregroove is 170 to 250 nm, preferably 180 to 230.
nm, particularly preferably 190 to 220 nm. If the full width at half maximum or the depth of the pre-groove is out of the above range, the modulation degree and the servo signal become small like the pre-pit, and the Orange Book standard may not be satisfied.

It is desirable that the cross-sectional shape of the pre-pit is substantially trapezoidal. This is because the depth of the prepit can be set by the resist film thickness because it is deeper than the pregroove, and the stamper can be easily manufactured. On the other hand, it is desirable that the pre-groove has a substantially V-shaped cross section. This is because if the pre-groove is a deep groove, the reflectance satisfying the Orange Book standard cannot be obtained, so it must be shallower than the depth of the pre-pit. Therefore, in terms of manufacturing the stamper, the pre-groove shape is preferably substantially V-shaped.

The material of the substrate may basically be transparent at the wavelengths of the recording light and the reproducing light. For example, a polymer material such as a polycarbonate resin, a vinyl chloride resin, an acrylic resin such as polymethylmethacrylate, a polystyrene resin, an epoxy resin, or an inorganic material such as glass is used. These substrate materials are formed into a disc-shaped substrate by an injection molding method or the like. Polycarbonate resin is most suitable in consideration of transparency and substrate moldability.

Next, a recording layer having a film thickness of about 10 to 200 nm is formed on the substrate. The recording layer in the present invention has a specific shape in the prepit portion and the pregroove portion. The details will be described below with reference to FIG.
In FIG. 1, a dye layer 2 made of a dye is formed on the surface of a substrate 1 made of resin, a reflective layer 3 made of a metal is formed on the dye layer 2, and a protective layer 4 is further formed on the reflective layer 3. There is. Pre-pits 6 and pre-grooves 5 are formed on the substrate 1. The dye layer 2 is formed by applying a dye coating solution prepared by dissolving a dye in an organic solvent by a spin coating method and drying it. When the method of applying the dye solution is used as described above, the dye is depressed and buried in accordance with the pre-pits 6 and the pre-grooves 5, so that the film thickness t _p of the dye layer 2 at the pit bottom 7 of the pre-pits 6 is the substrate. It is sufficiently larger than the film thickness t _pl of the dye layer 2 in the pre-pit portion 8 of No. 1. Assuming that the depth of the prepits is d _p , the depth δ _p of the prepits at the interface between the reflective layer 3 and the dye layer 2 is expressed by [Equation 5], as is apparent from [FIG. 1].

[0027]

Δ _p = d _p + t _pl −t _p The difference (L _p ) in the optical path length between the pre-pit bottom portion 7 and the pre-pit portion 8 is expressed by the following equation [Equation 6].

[0028]

L _p = n _s d _p + n _d (t _pl −t _p ) = n _s d _p + n _d (δ _p −d _p ) where n _s is the refractive index of the substrate 1 and n _d is This is the refractive index of the dye layer 2.

Usually, the refractive index (n _d ) of the dye layer is larger than the refractive index (n _s ) of the substrate, and the depth (d _p ) of the prepits is deeper than that of the conventional one. The difference in optical path length (L _p ) in the section 8 becomes large.

In the optical recording medium according to the present invention, the difference in the optical path length (L
_p ) is configured to be 0.20λ or more and 0.40λ or less, preferably 0.25λ or more and 0.35λ or less. When L _p is less than 0.20λ, the difference in optical path length between the pit bottom and the pit is too small, and when L _p exceeds 0.40λ, conversely, the difference in optical path length between the pit bottom and the pit is too large. , The degree of modulation decreases, and the Orange Book (CD-
R) Good signal characteristics satisfying the standards cannot be obtained. On the other hand, the pre-groove bottom part 9 and the pre-groove part 10
The difference (L _g ) in the optical path length at is expressed by the following equation [Equation 7].

[0031]

L _g = n _s d _g + n _d (t _gl −t _g ) = n _s d _g + n _d (δ _g −d _g ) where d _g is the depth of the pre-groove and δ _g is the reflective layer. 3 and the depth of the pre-groove at the interface between the dye layer 2 (δ _g = d _g
+ T _gl −t _g ), t _gl is the film thickness of the dye layer 2 in the pre-groove part 9, and t _g is the film thickness of the dye layer 2 in the pre-groove bottom part 8.

In the optical recording medium of the present invention, the difference (L) in the optical path length between the pre-groove bottom portion 9 and the pre-groove portion 10
_g ) is configured to be smaller than 0.15λ, preferably smaller than 0.10λ. When L _g exceeds 0.15λ, the optical path length is too large and the reflectance is lowered, so that the Orange Book (CD-R) standard cannot be satisfied.

The dye used in the recording layer in the present invention is not particularly limited per se, but a phthalocyanine dye, especially a phthalocyanine dye having a substituent and soluble in an organic solvent having a metal atom in the center is used. Is preferred. Examples of the substituent include halogen such as hydrogen, chlorine, bromine and iodine, a substituted or unsubstituted alkyl group, an aryl group, an unsaturated alkyl group, an alkoxyl group, an aryloxy group, an unsaturated alkoxyl group, an alkylthio group, an arylthio group. , Unsaturated alkylthio groups, carboxylic acid ester groups, carboxylic acid amide groups, silyl groups, amino groups and the like. Specific examples of the substituent include an alkyl group such as a methyl group, an ethyl group, an n-propyl group, and an n- group.
Butyl group, isobutyl group, n-pentyl group, neopentyl group, isoamyl group, 2-methylbutyl group, n-hexyl group, 2-methylpentyl group, 3-methylpentyl group,
4-methylpentyl group, 2-ethylbutyl group, n-heptyl group, 2-methylhexyl group, 3-methylhexyl group, 4-methylhexyl group, 5-methylhexyl group, 2
-Ethylhexyl group, 3-ethylpentyl group, n-octyl group, 2-methylheptyl group, 3-methylheptyl group, 4-methylheptyl group, 5-methylheptyl group, 2
-Ethylhexyl group, 3-ethylhexyl group, n-nonyl group, n-decyl group, primary alkyl group such as n-dodecyl group, isopropyl group, sec-butyl group, 1-ethylpropyl group, 1-methylbutyl group, 1, 2-dimethylpropyl group, 1-methylheptyl group, 1-ethylbutyl group,
1,3-dimethylbutyl group, 1,2-dimethylbutyl group, 1-ethyl-2-methylpropyl group, 1-methylhexyl group, 1-ethylheptyl group, 1-propylbutyl group, 1-isopropyl-2- Methylpropyl group, 1-ethyl-2-methylbutyl group, 1-propyl-2-methylpropyl group, 1-methylheptyl group, 1-ethylhexyl group, 1-propylpentyl group, 1-isopropylpentyl group, 1-isopropyl- 2-methylbutyl group, 1-
Secondary alkyl groups such as isopropyl-3-methylbutyl group, 1-methyloctyl group, 1-ethylheptyl group, 1-propylhexyl group, 1-isobutyl-3-methylbutyl group, tert-butyl group, tert-hexyl group,
Tertiary alkyl groups such as tert-amino group and tert-octyl group, cyclohexyl group, 4-methylcyclohexyl group, 4-ethylcyclohexyl group, 4-tert-butylcyclohexyl group, 4- (2-ethylhexyl) cyclohexyl group, bornyl A cycloalkyl group such as a group, an isobrunil group, and an adamantane group, and an aryl group includes a phenyl group, an ethylphenyl group, a butylphenyl group, a nonylphenyl group, a naphthyl group, a butylnaphthyl group, a nonylnaphthyl group, and the like. The unsaturated alkyl group, ethylene group, propylene group, butylene group, hexene group, octene group, dodecene group, cyclohexene group,
A butylhexene group and the like can be mentioned. Further, these alkyl group, aryl group and unsaturated alkyl group may be substituted with a hydroxyl group, a halogen group or the like, and may be substituted with the alkyl group or aryl group via an atom such as oxygen, sulfur or nitrogen. May be. Examples of the alkyl group or aryl group substituted via oxygen include a methoxymethyl group, a methoxyethyl group, an ethoxymethyl group, an ethoxyethyl group,
Butoxyethyl group, ethoxyethoxyethyl group, phenoxyethyl group, methoxypropyl group, ethoxypropyl group, methoxyphenyl group, butoxyphenyl group, polyoxyethylene group, polyoxyethylene group, polyoxypropylene group, etc. Examples of the substituted alkyl group or aryl group include a methylthioethyl group, an ethylthioethyl group, an ethylthiopropyl group, a phenylthioethyl group, a methylthiophenyl group, and a butylthiophenyl group, which are substituted through nitrogen. Examples of the group and the aryl group include a dimethylaminoethyl group, a diethylaminoethyl group, a diethylaminopropyl group, a dimethylaminophenyl group and a dibutylaminophenyl group.

On the other hand, the central metal of the phthalocyanine dye is preferably a divalent metal, specifically, Ca or M.
g, Zn, Cu, Ni, Pd, Fe, Pb, Co, P
Examples thereof include t, Cd, Ru and the like. The content of these dyes in the recording layer is not particularly limited, but is usually 30-
It is about 100% by weight.

The above phthalocyanine dyes may be used as a mixture of two or more kinds of phthalocyanine dyes, if necessary, and as long as the effects of the present invention are not impaired, a light absorber, a combustion accelerator, a quencher, Additives such as UV absorbers, adhesives and resin binders may be mixed or introduced as a substituent.

The light absorber has absorption at the wavelength of recording light,
An organic dye is desirable because it is for increasing the sensitivity of the phthalocyanine dye film. For example, naphthalocyanine dyes, porphyrin dyes, azo dyes, pentamethine cyanine dyes, squarylium dyes, pyrylium dyes, thiopyrylium dyes, azurenium dyes, naphthoquinone dyes, anthraquinone dyes, indophenol dyes, Triphenylmethane dyes, xanthene dyes, indanthrene dyes, indigo dyes, thioindigo dyes, merocyanine dyes, thiazine dyes, acridine dyes, and oxazine dyes are often used. Phthalocyanine dyes are particularly desirable in terms of absorption wavelength region. It is also possible to use a mixture of a plurality of these dyes.

Examples of the combustion accelerator are lead compounds such as tetraethyl lead and tetramethyl lead which are metallic anti-knocking agents, and Mn compounds such as simantrene (Mn (C ₅ H ₅ ) (CO) ₃ ). , And iron biscyclopentadienyl complex (ferrocene), which is a metallocene compound,
Ti, V, Mn, Cr, Co, Ni, Mo, Ru, R
Examples thereof include biscyclopentadienyl metal complexes such as h, Zr, Lu, Ta, W, Os, Ir, Sc and Y. Among them, ferrocene, ruthenocene, osmocene, nickelocene, titanocene and their derivatives have a good combustion promoting effect. As the iron-based metal compound, in addition to metallocene, iron formate, iron oxalate, iron laurate, iron naphthenate, iron stearate, iron butyrate and other organic acid iron compounds, acetylacetonato iron complex, phenanthroline iron complex, bispyridine Iron complex, ethylenediamineiron complex, ethylenediaminetetraacetate iron complex, diethylenetriamineiron complex, diethyleneglycoldimethyletheriron complex, diphosphinoiron complex, dimethylglyoximate iron complex, etc. chelate iron complex, carbonyliron complex, cyanoiron complex, ammineiron complex, etc. Iron complex, ferrous chloride, ferric chloride, ferrous bromide,
Examples thereof include iron halides such as ferric iron, inorganic iron salts such as iron nitrate and iron sulfate, and iron oxide. The iron-based metal compound used here is soluble in organic solvents,
In addition, it is desirable that the wet heat resistance and the light resistance are good. Particularly, acetylacetonato iron complex, iron carbonyl complex and the like are very preferable in that good solubility can be obtained.
The above combustion accelerator introduces a substituent if necessary,
Multiple substances may be mixed or an additive substance such as a binder may be added. These dyes are formed on a substrate by a coating method such as a spin coating method or a casting method, a sputtering method, a chemical vapor deposition method, a vacuum vapor deposition method or the like. In the present invention, the spin coating method is most suitable for forming the dye film having a specific shape in the pit portion and the groove portion.

In the spin coating method, a coating solution in which a dye is dissolved or dispersed is used. At this time, the solvent must be selected so as not to damage the substrate. For example, n-hexane, n-octane, aliphatic hydrocarbon solvents such as isooctane, cyclohexane, methylcyclohexane, ethylcyclohexane, propylcyclohexane, dimethylcyclohexane, cyclic hydrocarbon solvents such as diethylcyclohexane, benzene, toluene, xylene, Aromatic hydrocarbon solvents such as ethylbenzene, chloroform, carbon tetrachloride, dichloromethane, 2,2,3
Halogenated hydrocarbon solvent such as 3-tetrafluoro-1-propanol, alcohol solvent such as methanol, ethanol, 1-propanol, 2-propanol, diacetone alcohol, dioxane, tetrahydrofuran, diethyl ether, dibutyl ether, diisopropyl ether, etc. Examples of the ether solvent, cellosolve solvent such as methyl cellosolve and ethyl cellosolve, ketone solvent such as acetone and methyl isobutyl ketone, ester solvent such as ethyl acetate, methyl acetate and butyl acetate. These organic solvents may be used alone or in combination of two or more.

In forming the phthalocyanine dye film, the boiling point of n-octane, ethylcyclohexane, dimethylcyclohexane, etc. is 12 in the above coating solvent.
An organic solvent at about 0 to 140 ° C. is used alone, or a coating solvent obtained by mixing these with dioxane, xylene, toluene, propylcyclohexane or the like at a volume ratio of about 0.1 to 10% is preferably used.

As a preferable coating condition, for example, a low speed rotation (100 to 10
(00 rpm) for 1 to 10 seconds, and immediately thereafter, high speed rotation (2000 to 5000 rpm) applies 10 to 6
A uniform dye film can be formed by drying for 0 seconds. Further, the recording layer is not limited to one layer, and a plurality of dyes may be formed in multiple layers as required.

Next, on the recording layer, a thickness of 50 to 300 nm,
Preferably, a reflective layer having a thickness of 100 to 150 nm is formed. The material of the reflective layer has a sufficiently high reflectance at the wavelength of the reproduction light, such as Au, Al, Ag, Cu, Ti, Cr,
Metals of Ni, Pt, Ta, Cr and Pd can be used alone or as an alloy. Among these, Au
And Al have a high reflectance and are suitable as a material for the reflective layer.
Other than the above, the following may be included. For example,
Mg, Se, Hf, V, Nb, Ru, W, Mn, Re,
Fe, Co, Rh, Ir, Cu, Zn, Cd, Ga, I
Metals and semimetals such as n, Si, Ge, Te, Pb, Po, Sn and Bi can be mentioned. Further, a material containing Au as a main component is preferable because a reflective layer having a high reflectance can be easily obtained. Here, the main component means that the content rate is, for example, 50% or more. It is also possible to stack a low refractive index thin film and a high refractive index thin film alternately with a material other than metal to form a multilayer film and use it as a reflective layer.

As a method of forming the reflective layer, for example,
Examples thereof include a sputtering method, a chemical vapor deposition method, a vacuum vapor deposition method and the like. Among them, the sputtering method is the most widely used method. Further, a reflection amplification layer or an adhesive layer may be provided between the recording layer and the reflection layer in order to increase the reflectance or improve the adhesion.

Further, a protective layer may be formed on the reflective layer. The material of the protective layer is not particularly limited as long as it protects the reflective layer from external force. Examples of the organic substance include a thermoplastic resin, a thermosetting resin, a UV curable resin, and the like. For example, a UV curable resin is preferable. Further, as the inorganic substance, SiO ₂ , SiN ₄ , Mg
F _2, SnO ₂ and the like. A thermoplastic resin, a thermosetting resin, etc. can be formed by dissolving in a suitable solvent, applying a coating solution, and drying. The UV curable resin can be formed as it is or by dissolving it in a suitable solvent to prepare a coating solution, applying the coating solution, and irradiating it with UV light to cure it. As the UV curable resin, for example, an acrylate resin such as urethane acrylate, epoxy acrylate, polyester acrylate can be used. These materials may be used alone or as a mixture, and may be used not only as a single layer but also as a multilayer film. As a method of forming the protective layer, a coating method such as a spin coating method or a casting method, a sputtering method, a chemical vapor deposition method, or the like is used as in the recording layer, and among them, the spin coating method is preferable. The optical recording medium thus manufactured has signal characteristics satisfying the Orange Book (CD-R) standard, and is commercially available from conventional CD players and CDs.
-It can be reproduced well even with a ROM player.

[0044]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited thereto. [Embodiment 1] A prepit in which an EFM signal having a track pitch of 1.6 µm, a pit half-value width of 0.50 µm, and a pit depth (d _p ) of 300 nm is recorded is formed in a region of a diameter of 46 mm to 80 mm, and a diameter of 80 mm. Track pitch of 1.6 μm, half width of groove (W _g ) 0.35 μm, depth of groove (d _g ) 210
nm of the pregroove is formed disk-like polycarbonate substrate (outer diameter 120 mm, thickness 1.2 mm, refractive index (n _s) 1.58) was used. On the other hand, 0.25 g of the phthalocyanine dye represented by [Chemical Formula 1] was dissolved in 10 ml of a coating solvent obtained by adding 3% o-xylene to ethylcyclohexane to prepare a dye solution.

[0045]

Embedded image

This dye solution was applied onto the above substrate by spin coating at a substrate rotation speed of 750 rpm for 5 seconds and then dried at a rotation speed of 3000 rpm for 10 seconds to form a dye layer, and then at 70 ° C. for 2 hours. It was dried by heating to remove the residual solvent. At this time, the refractive index (n _d ) of the dye film is 2.20.
Met. At this time, the average film thickness of the dye was about 100 nm.

Au was sputtered on the dye layer using a spattering apparatus (CDI-900) manufactured by Balzers,
A reflective layer having a thickness of 100 nm was formed. Argon gas was used as the sputtering gas. Sputtering conditions are sputter power 2.5 kW, sputter gas pressure 1.0 × 10 ^-2 To
performed at rr. Furthermore, the UV curable resin SD is applied on the reflective layer.
After spin-coating -17 (manufactured by Dainippon Ink and Chemicals, Inc.), it was irradiated with ultraviolet rays to form a protective layer having a thickness of 6 μm.

Using a commercially available CD writer (CDD521 manufactured by Philips), the groove portion of the sample was subjected to EFM.
The signal was recorded. After recording, a signal was reproduced using an optical disc evaluation device DDU-1000 manufactured by Pulstec Industrial Co., Ltd. equipped with a 780 nm red semiconductor laser head, the reflectance and the modulation factor of the 11T signal were measured with a digital oscilloscope, and a KENWOOD CD decoder was used. Used to measure the error rate. Further, in order to calculate the optical path length difference (L _p ) between the pit bottom part and the pit part and the optical path length difference (L _g ) between the groove bottom part and the groove part of the sample, a dye layer is formed on the substrate and then the thickness is increased. Using an Au sputtered film having a thickness of about 10 nm, the depressions (δ _p and δ _g ) in the dye film at the pits and the grooves were measured using a scanning tunneling microscope (Kurasurf-101A). The recess depth measured pit portion and the dye layer of the groove portion from the equation [equation 8] follows using as the value of the [delta] _p and [delta] _g, were calculated L _p and L _g.

[0049]

[Equation 8] L _p = n _s d _p + n _d (δ _p −d _p ) L _g = n _s d _g + n _d (δ _g −d _g ) As a result of evaluating the signal characteristics, as shown in [Table 1]. In both the pre-pit part and the pre-groove part, the 11T modulation and reflectance are orange book standards (11T modulation is 60% or more,
Good characteristics satisfying a reflectance of 65% or more were obtained.

[0050]

[Table 1]

Example 2 A medium was prepared in the same manner as in Example 1 except that dimethylcyclohexane + 4% o-xylene was used as the coating solvent, and δ _p and δ _g were determined by the same method as in Example 1. It measured and _Lp and _Lg were calculated _| required. As a result of evaluating the signal characteristics, as shown in [Table 1], the 11T modulation degree and the reflectance of both the prepit portion and the pregroove portion are Orange Book standards (11T modulation degree is 60% or more,
Good characteristics satisfying a reflectance of 65% or more were obtained.

Example 3 A medium was prepared in the same manner as in Example 1 except that ethylcyclohexane + 1% propylcyclohexane was used as the coating solvent, and δ _p and δ _g were measured by the same method as in Example 1. Then, L _p and L _g were obtained. As a result of evaluating the signal characteristics, as shown in [Table 1], the 11T modulation degree and the reflectance of both the repit portion and the pre-groove portion are Orange Book standard (11T modulation degree is 60%).
%, The reflectance is 65% or more), and good characteristics were obtained.

[Embodiment 4] The same procedure as in Embodiment 1 was carried out except that the half width (W _p ) of the prepit was 0.55 μm and the half width (W _g ) of the pre-groove was 0.40 μm. A medium was prepared and δ _p and δ were prepared in the same manner as in Example 1.
_g was measured and L _p and L _g were determined. As a result of evaluating the signal characteristics, as shown in [Table 1], the 11T modulation degree and the reflectance of both the prepit portion and the pregroove portion are Orange Book standard (11T modulation degree is 60% or more, reflectance is 65%.
Good characteristics satisfying the above) were obtained.

Example 5 A medium was prepared in the same manner as in Example 4 except that the prepit depth (d _p ) was 250 nm and the coating solvent was ethylcyclohexane. Δ _p and δ _g with
_p and L _g were determined. As a result of evaluating the signal characteristics, as shown in [Table 1], the 11T modulation degree and the reflectance of both the prepit portion and the pregroove portion are in accordance with the Orange Book standard (1
Good characteristics satisfying a 1T modulation of 60% or more and a reflectance of 65% or more were obtained.

Example 6 A medium was prepared in the same manner as in Example 5 except that dimethylcyclohexane + 1% o-xylene was used as the coating solvent, and δ _p and δ _g were determined by the same method as in Example 1. It measured and _Lp and _Lg were calculated _| required. As a result of evaluating the signal characteristics, as shown in [Table 1], the 11T modulation degree and the reflectance of both the prepit portion and the pregroove portion are Orange Book standards (11T modulation degree is 60% or more,
Good characteristics satisfying a reflectance of 65% or more were obtained.

Comparative Example 1 A medium was prepared in the same manner as in Example 1 except that the coating solvent was propylcyclohexane + 6% toluene, and δ _p and δ _g were measured by the same method as in Example 1. Then, L _p and L _g were obtained. As a result of evaluating the signal characteristics, as shown in [Table 1], the prepit portion has a small degree of modulation, a large number of errors occur, reproduction is poor, and the pregroove portion also has a small reflectance and modulation degree.
An error occurred and I could not meet the Orange Book standard.

Comparative Example 2 A medium was prepared in the same manner as in Example 1 except that the prepit depth (d _p ) was 250 nm and the coating solvent was propylcyclohexane + 6% toluene. In a similar way δ _p and δ
_g was measured and L _p and L _g were determined. As a result of evaluating the signal characteristics, as shown in [Table 1], the prepit portion has a small degree of modulation, a large number of errors occur, reproduction is poor, and the pregroove portion also has a small reflectance and modulation degree and an error. It occurred and could not satisfy the Orange Book standard.

[Comparative Example 3] In Example 1, the half width of the prepit (W _p ) was 0.55 μm, the half width of the pre-groove (W _g ) was 0.40 μm, and the depth of the pre-groove (d).
_g ) was 230 nm and the coating solvent was propylcyclohexane + 6% toluene. A medium was prepared in the same manner, and δ _p and δ _g were measured by the same method as in Example 1, and L
_p and L _g were determined. As a result of evaluating the signal characteristics, as shown in [Table 1], the prepit portion has a small degree of modulation, a large number of errors occur, reproduction is poor, and the pregroove portion also has a small reflectance and modulation degree and an error occurs. However, I was not able to meet the Orange Book standard.

[Comparative Example 4] In the same manner as in Example 1, except that the prepit depth (d _p ) was 250 nm, the pregroove depth (d _g ) was 230 nm, and the coating solvent was dibutyl ether. A medium was prepared, δ _p and δ _g were measured in the same manner as in Example 1, and L _p and L _g were obtained. As a result of evaluating the signal characteristics, as shown in [Table 1], the prepit portion has a small degree of modulation, a large number of errors occur, reproduction is poor, and the pregroove portion also has a small reflectance and modulation degree and an error occurs. However, I was not able to meet the Orange Book standard.

Comparative Example 5 A medium was prepared in the same manner as in Comparative Example 4 except that the coating solvent was ethylcyclohexane + 8% toluene.
_P and δ _g were measured to determine L _p and L _g . As a result of evaluating the signal characteristics, as shown in [Table 1], the prepit portion has a small degree of modulation, a large number of errors occur, reproduction is poor, and the pregroove portion also has a small reflectance and modulation degree and an error. It occurred and could not satisfy the Orange Book standard.

Comparative Example 6 A medium was prepared in the same manner as in Comparative Example 2 except that propylcyclohexane was used as the coating solvent, and δ _p and δ _g were measured by the same method as in Example 1 to obtain L _p. And L _g were determined. As a result of evaluating the signal characteristics, as shown in Table 1, the prepit portion has a small modulation degree, a large number of errors occur, and reproduction is poor, and the pregroove portion also has a small reflectance and modulation degree and an error occurs. I could not meet the Orange Book standard.

[0062]

As described above, according to the present invention, the full width at half maximum of the pits in the prepit portion is 0.4 to 0.7 μm,
The depth is set to 200 to 400 nm, the optical path length difference between the pit bottom portion and the pit portion is set to 0.20λ (where λ is the wavelength of the reproducing laser light) or more and 0.40λ or less, and the groove in the pre-groove portion is By setting the half width to 0.3 to 0.6 μm and the optical path length difference between the groove bottom portion and the groove portion to 0.15λ or less, a hybrid disc having good signal characteristics satisfying the Orange Book standard can be obtained. It becomes possible to provide.

[Brief description of drawings]

FIG. 1 is a cross-sectional structure diagram of an optical recording medium.

[Explanation of symbols]

1 substrate 2 recording layer 3 reflective layer 4 protective layer 5 pre-groove 6 pre-pit 7 pre-pit bottom 8 pre-pit area 9 pre-groove bottom 10 pre-groove area d _p pre-pit depth t _p dye thickness on pre-pit bottom t _pl pre-pit Dye film thickness on the interspace δ _p Prepit depth at the interface between the reflective layer 3 and the dye layer 2 d _g Pregroove depth t _g Dye film thickness on the bottom of the pregroove t _gl Dye film on the pregroove space Thickness δ _g Depth of pregroove at the interface between reflective layer 3 and dye layer 2

Claims (3)

[Claims] 1. An optical recording medium in which a dye layer, a reflective layer, and a protective layer are provided in this order on a disk-shaped substrate on which prepits and pregrooves are formed, the prepits having a half-value width of 0.4 to 0.7 μm, a depth of 200 to 400 nm, and a difference in optical path length between the pit portion and the pit portion is 0.20λ (where λ is the wavelength of the reproducing laser light) or more and 0.40λ or less. , The pregroove has a half width of 0.
3 to 0.6 μm, a depth of 170 to 250 nm, and a difference in optical path length between the groove portion and the groove portion is 0.15λ (where λ is the wavelength of the reproducing laser light) or less. Characteristic optical recording medium. 2. The optical recording medium according to claim 1, wherein the dye layer comprises a phthalocyanine dye. 3. The optical recording medium according to claim 1, wherein the reflective layer is made of a metal containing Au as a main component.