Write once type information recording medium, and its coloring material

The present invention relates to a write-once information recording medium capable of recording and reproducing information by a short wavelength laser beam such as a blue laser beam and a dye material thereof.

As is well known, in recent years, with the spread of personal computers and the like, the importance of media for storing digital data has increased. For example, at present, information recording media capable of digitally recording and reproducing long-time video information, audio information, and the like have become widespread. In addition, information recording media for digital recording and reproduction have also been used in mobile devices such as mobile phones.

Here, as this kind of information recording medium, it has a large recording capacity of information, has high random access performance capable of quickly searching for desired recorded information, and is compact and lightweight, and has excellent storage stability and portability. Moreover, disc-shaped ones are often used because they are economically inexpensive and the like.

At present, as such a disc-shaped information recording medium, a so-called optical disc, which can record and reproduce information in a non-contact manner by irradiating a laser beam, has become the mainstream. This optical disc mainly complies with the CD (Compact Disk) standard or the DVD (Digital Versatile Disk) standard, and compatibility between the two standards is also provided.

Optical discs include read-only types such as CD-DA (Digital Audio), CD-ROM (Read Only Memory), DVD-V (Video), and DVD-ROM, which cannot record information, and CD-R (Recordable). ), DVD-R, etc., which allows you to write information only once, and CD-RW (ReWritable), DVD-RW, etc., which allows you to rewrite information as many times as you like. There are three types.

Of these, write-once optical discs that use an organic dye for the recording layer are the most widespread as those capable of recording because of their low manufacturing cost. This is because when the recording capacity of information exceeds 700MB (Mega Bytes), there is almost no use for erasing the recorded information and rewriting it with new information, and it is sufficient to record it only once. is there.

In a write-once optical disc that uses an organic dye for the recording layer, when the recording area (track) defined by the groove is irradiated with laser light and the resin substrate is heated above the glass transition point Tg, the organic dye film in the groove is formed. As a result of causing a photochemical reaction to generate a negative pressure, the resin substrate is deformed in the groove to form a recording mark.

A typical organic dye used for a CD-R having a recording / playback laser beam wavelength of about 780 nm is a phthalocyanine dye such as IRGAPHOR Ultragreen MX manufactured by Ciba Specialty Chemicals. Further, a typical organic dye used for DVD-R having a wavelength of laser light for recording / reproduction of about 650 nm is an azo metal complex dye manufactured by Mitsubishi Chemical Media.

By the way, in the next-generation optical disc that realizes higher density and higher performance recording / reproduction than the current optical disc, a blue laser beam having a wavelength of about 405 nm is used as the recording / reproducing laser beam. However, an organic dye material capable of obtaining practically sufficient recording / reproducing characteristics by using such short wavelength light has not been developed so far.

That is, in the current optical discs that perform recording / reproduction using infrared laser light or red laser light, an organic dye material having an absorption maximum on the shorter wavelength side than the wavelength (780 nm, 650 nm) of the recording / reproducing laser light is used. .. As a result, in the current optical disc, the light reflectance of the recording mark portion formed by irradiating the laser beam is lower than the light reflectance before the laser beam irradiation, that is, so-called H (High) to L (Low). Realizes the characteristics.

On the other hand, when recording / reproducing using blue laser light, an organic dye material having an absorption maximum on the shorter wavelength side than the wavelength (405 nm) of the recording / reproducing laser light has stability against ultraviolet rays and storage durability. Not only is it poor, but it is also poorly stable against heat, and has the problem of low contrast and resolution of recorded marks.

In addition, since the bleeding of the recording mark tends to be large, it affects the adjacent tracks and the cross light characteristics are likely to be deteriorated. Further, the recording sensitivity is also lowered, and there is an inconvenience that a sufficient reproduction signal SN (Signal to Noise) ratio and bit error rate cannot be obtained.

In addition, under the condition that the information is not recorded on the adjacent track, the recording sensitivity may be obtained for the time being, but if the information is recorded on the adjacent track, the cross light to the adjacent track is large, so that the reproduction signal The signal-to-noise ratio becomes low, the bit error rate becomes high, and the level does not reach a level suitable for practical use.

Patent Document 1 discloses an optical recording medium in which the absorption maximum of the organic dye compound contained in the recording layer is longer than the wavelength of the writing light. However, Patent Document 1 does not describe any configuration that enhances the performance of the optical disc itself, such as a change in light reflectance before and after laser irradiation, a reproduced signal SN ratio, and a bit error rate. is there.<patcit num="1"><text>JP-A-2002-74740</text></patcit>

<p> Therefore, the present invention has been made in consideration of the above circumstances. For example, a short wavelength laser beam such as a blue laser beam is used to record and reproduce information at a high density and with sufficiently practically suitable level of performance. It is an object of the present invention to provide a write-once information recording medium and a dye material thereof.</p>

<p> The write-once information recording medium according to the present invention includes a transparent resin substrate on which concentric or spiral grooves are formed and a recording film formed on the grooves on the transparent resin substrate, and is irradiated with short wavelength laser light. The recording mark is formed by the above, and the light reflectance of the recording mark portion formed by the irradiation of the short wavelength laser light is higher than the light reflectance before the irradiation of the short wavelength laser light. It is a thing.</p><p> Further, the dye material for a write-once information recording medium according to the present invention includes a transparent resin substrate having concentric or spiral grooves formed therein, a recording film formed so as to fill the grooves on the transparent resin substrate, and the like. An organic dye material used for a recording film of a write-once information recording medium having a metal reflecting film formed on a recording film and a recording mark formed by irradiation with a short wavelength laser light, and a part or all of the material. Is composed of a dye part and an anion part made of an organic metal complex, and the light reflectance of the recording mark part formed by irradiation with short wavelength laser light is higher than the light reflectance before irradiation with short wavelength laser light. It is configured to have high characteristics.</p>

<p> According to the above invention, since the recording film having a higher light reflectance of the recording mark portion formed by the irradiation than before the irradiation of the short wavelength laser light is provided, even if the short wavelength laser light is used. It is excellent in storage durability, reproduction signal SN ratio, bit error rate, etc., and can record and reproduce information with high density and sufficiently practically suitable level of performance.</p>

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The write-once information recording medium described in this embodiment includes a transparent resin substrate formed in a disk shape from a synthetic resin material such as polycarbonate. Grooves are formed concentrically or spirally on this transparent resin substrate. This transparent resin substrate can be manufactured by injection molding using a stamper.

Then, a recording film containing an organic dye is formed on the transparent resin substrate so as to fill the groove. As the organic dye forming this recording film, a dye whose maximum absorption wavelength region is shifted to a longer wavelength side than the recording wavelength (405 nm) is used. Further, the absorption is not extinguished in the recording wavelength region, but is designed to have a considerable light absorption.

As a result, when the track before information recording is focused or tracked by the recording laser beam, the light reflectance becomes low. The laser light causes a decomposition reaction of the dye, and the light absorption rate decreases, so that the light reflectance of the recording mark portion increases. Therefore, the so-called L to H characteristic that the light reflectance of the recording mark portion formed by irradiating the laser beam is higher than the light reflectance before the laser beam irradiation is realized.

The heat generated may cause the transparent resin substrate, particularly the bottom of the groove, to be deformed. In this case, a phase difference may occur in the reflected light.

The organic dye can be made into a liquid by dissolving it in a solvent, and can be easily applied to the surface of a transparent resin substrate by a spin coating method. In this case, the film thickness can be controlled with high accuracy by controlling the dilution rate with the solvent and the rotation speed at the time of spin coating.

The organic dye consists of a dye part and a counterion (anion) part. As the pigment portion, a cyanine pigment, a styryl pigment, or the like can be used. In particular, cyanine dyes and styryl dyes are suitable because the absorption rate with respect to the recording wavelength can be easily controlled.

Among them, the monomethine cyanine dye having a monomethine chain has a maximum absorption and an absorbance in the recording wavelength range (400 nm to 405 nm) of about 0.3 to 0.5, preferably around 0.3 to 0.5, by thinning the recording film applied to the transparent resin substrate. It can be easily adjusted to around 0.4. Therefore, it is possible to improve the recording / reproducing characteristics, and it is possible to design both the light reflectance and the recording sensitivity.

As the anion portion, it is preferable to use an organometallic complex from the viewpoint of photostability. The organometallic complex having cobalt or nickel as the central metal is particularly excellent in photostability.

The azo metal complex is the best, and the solubility when 2,2,3,3-tetrafluoro-1-propanol (TFP) is used as a solvent is also good, so that a solution for spin coating can be easily prepared. Can be done. In addition, since it can be recycled after spin coating, it is possible to reduce the cost of manufacturing an optical disc.

FIG. 1 shows four examples of dyes A to D as organic dye materials. The dye A has a dye portion (cation portion) as a styryl dye and an anion portion as an azo metal complex 1. The dye C has a dye portion (cation portion) as a styryl dye and an anion portion as an azo metal complex 2. The dye D has a dye part (cation part) as a monomethicyanine dye and an anion part as an azo metal complex 1. A simple substance of the organometallic complex can also be used. For example, dye B is a nickel complex dye.

Then, the disk substrate coated with the organic dye thin film after the spin coating is dried with a hot plate or a clean oven at a temperature of about 80 ° C., and then sputtered onto the thin film to form an antireflection film. A metal thin film is formed. As the metal reflective film material, for example, Au, Ag, Cu, Al or an alloy thereof, an alloy or the like is used.

After that, a write-once optical disc is manufactured as a write-once information recording medium by spin-coating an ultraviolet curable resin on a metal film and laminating a protective disk substrate.

Here, the general formula 1 shows the general formula of the styryl dye which becomes the dye part of the dyes A and C, and the general formula 2 shows the general formula of the azo metal complex which becomes the anion part of the dyes A and C. .. Further, the general formula 3 shows the general formula of the monomethinecyanine dye which is the dye part of the dye D, and the general formula 4 shows the general formula of the azo metal complex which is the anion part of the dye D.<chemistry num="1"><img file="JP2005293772A_D0001.tif" /></chemistry>

<chemistry num="2"><img file="JP2005293772A_D0002.tif" /></chemistry>

<chemistry num="3"><img file="JP2005293772A_D0003.tif" /></chemistry>

<chemistry num="4"><img file="JP2005293772A_D0004.tif" /></chemistry>

In the general formula of the styryl dye, Z3 represents an aromatic ring, and the aromatic ring may have a substituent. Y31 represents a carbon atom or a hetero atom. R31, R32, and R33 represent aliphatic hydrocarbon groups that are the same as or different from each other, and these aliphatic hydrocarbon groups may have a substituent. R34 and R35 each independently represent a hydrogen atom or an appropriate substituent, and when Y31 is a heteroatom, either or both of R34 and R35 are absent.

Further, in the general formula of the monomethinecyanine dye, Z1 and Z2 represent the same or different aromatic rings, and these aromatic rings may have a substituent. Y11 and Y12 independently represent carbon atoms or heteroatoms. R11 and R12 represent aliphatic hydrocarbon groups, and these aliphatic hydrocarbon groups may have a substituent. R13, R14, R15, and R16 each independently represent a hydrogen atom or an appropriate substituent, and when Y11 and Y12 are heteroatoms, part or all of R13, R14, R15, and R16 are absent.

The monomethicyanin dye used in this embodiment includes an imidazoline ring, an imidazole ring, which may have one or more substituents at both ends of a monomethine chain which may have one or more substituents, and which are the same or different from each other. Benzoimidazole ring, α-naphthoimidazole ring, β-naphthoimidazole ring, indole ring, isoindole ring, indolenin ring, isoindrenine ring, benzoindrenine ring, pyridinoindrenine ring, oxazoline ring, oxazole ring , Isooxazole ring, benzoxazole ring, pyridinooxazole ring, α-naphthoxazole ring, β-naphthoxazole ring, selenazoline ring, selenazole ring, benzoselenazole ring, α-naphthoselazole ring, β-naphthoselazole ring , Thiazoline ring, thiazole ring, isothiazole ring, benzothiazole ring, α-naphthiazole ring, β-naphthiazole ring, tellurazoline ring, tellurazole ring, benzoterazole ring, α-naphtholazole ring, β-naphtholazole ring Rings, as well as aclysine rings, anthracene rings, isoquinoline rings, isopyrrole rings, imidazoline rings, indandione rings, indazole rings, indarin rings, oxazole rings, carbazole rings, xanthene rings, quinazoline rings, quinoxalin rings, quinoline rings, Chroman ring, cyclohexanedione ring, cyclopentandione ring, synnoline ring, thiazole ring, thiooxazoledone ring, thiophene ring, thionaphthene ring, thiobarbituric acid ring, thiohydrantin ring, tetrazole ring, triazine ring, naphthalene ring, naphthylidine ring Piperazin ring, pyrazine ring, pyrazole ring, pyrazoline ring, pyrazolidine ring, pyrazolone ring, pyran ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrylium ring, pyrrolidine ring, pyrrolin ring, pyrrole ring, phenazine ring, phenanthridin ring, Phenantren ring, phenanthrolin ring, phthalazine ring, pteridine ring, flazan ring, furan ring, purine ring, benzene ring, benzoxazole ring, benzopyran ring, morpholinExamples thereof include pigments formed by binding cyclic nuclei such as a ring and a rhodanine ring.

In addition, through the general formulas of monomethinecyanine dyes and styryl dyes, Z1 to Z3 represent, for example, aromatic rings such as benzene ring, naphthalene ring, pyridine ring, quinoline ring, and quinoxaline ring, and these aromatic rings have substituents. You may have one or more. Examples of the substituent include a methyl group, a trifluoromethyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group and a tert. -Alipid hydrocarbon groups such as pentyl group, 1-methylpentyl group, 2-methylpentyl group, hexyl group, isohexyl group, 5-methylhexyl group, heptyl group, octyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group. , Alicyclic hydrocarbon group such as cyclohexyl group, phenyl group, biphenylyl group, o-tolyl group, m-tolyl group, p-tolyl group, xsilyl group, mesityl group, o-cumenyl group, m-cumenyl group, p -Aromatic hydrocarbon groups such as cumenyl group, methoxy group, trifluoromethoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, sec-butoxy group, tert-butoxy group, pentyloxy group, phenoxy group, benzoyl Halogen such as ether group such as oxy group, methoxycarbonyl group, trifluoromethoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, ester group such as acetoxy group and benzoyloxy group, fluoro group, chloro group, bromo group and iodo group. Group, methylthio group, ethylthio group, propylthio group, butylthio group, phenylthio group and other thio groups, methylsulfamoyl group, dimethylsulfamoyl group, ethylsulfamoyl group, diethylsulfamoyl group, propylsulfamoyl group , Dipropyl sulfamoyl group, butyl sulfamoyl group, sulfamoyl group such as dibutyl sulfamoyl group, primary amino group, methyl amino group, dimethyl amino group, ethyl amino group, diethyl amino group, propyl amino group, dipropyl Amino group, isopropylamino group, diisopropylamino group, Amino groups such as tylamino group, dibutylamino group and piperidino group, methylcarbamoyl group, dimethylcarbamoyl group, ethylcarbamoyl group, diethylcarbamoyl group, propylcarbamoyl group, carbamoyl group such as dipropylcarbamoyl group, and hydroxy group and carboxy group. Examples thereof include a group, a cyano group, a nitro group, a sulfino group, a sulfo group, a mesyl group and the like. In the general formula, Z1 and Z2 may be the same or different from each other.

Y11, Y12, Y31 in the general formulas of monomethinecyanine dyes and styryl dyes represent carbon atoms or heteroatoms. Examples of the hetero atom include group 15 and group 16 atoms in the periodic table such as nitrogen atom, oxygen atom, sulfur atom, selenium atom, and tellurium atom. The carbon atoms in Y11, Y12, and Y31 may be, for example, an atomic group mainly composed of two carbon atoms such as an ethylene group and a vinylene group. Further, Y11 and Y12 in the general formula of the monomethinecyanine pigment may be the same or different from each other.

R11, R12, R13, R32, R33 in the general formulas of monomethinecyanine pigments and styryl pigments represent aliphatic hydrocarbon groups. Examples of aliphatic hydrocarbon groups are methyl group, ethyl group, propyl group, isopropyl group, isopropenyl group, 1-propenyl group, 2-propenyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl. Group, 2-butenyl group, 1,3-butadienyl group, pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 1-methylpentyl group, 2-methylpentyl group, 2-pentenyl group, hexyl group, isohexyl group , 5-Methylhexyl group, heptyl group, octyl group and the like. This aliphatic hydrocarbon group may have one or more substituents similar to those in Z1 to Z3.

In addition, R11, R12 in the general formula of the monomethicyanine dye and R13, R32, R33 in the general formula of the styryl dye may be the same or different from each other.

R13 to R16, R34, and R35 in the general formulas of monomethinecyanine dyes and styryl dyes independently represent hydrogen atoms or appropriate substituents in the individual general formulas. Examples of the substituent include a methyl group, a trifluoromethyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group and a tert. -Adioxide group such as pentyl group, 1-methylpentyl group, 2-methylpentyl group, hexyl group, isohexyl group, 5-methylhexyl group, heptyl group, octyl group, methoxy group, trifluoromethoxy group, ethoxy A group, a propoxy group, a butoxy group, a tert-butoxy group, a pentyloxy group, a phenoxy group, an ether group such as a benzoyloxy group, a halogen group such as a fluoro group, a chloro group, a bromo group, an iodo group, and a hydroxy group. Examples thereof include a carboxy group, a cyano group and a nitro group. In the general formula of monomethicyanine dye and styryl dye, when Y11, Y12, Y31 are heteroatoms, a part or all of R13 to R16 in Z1 and Z2, or one of R34 and R35 in Z3. Or both will not exist.

Further, in the general formula of the above azo metal complex, A and A ́ contains one or more heteroatoms selected from nitrogen atom, oxygen atom, sulfur atom, selenium atom and tellurium atom, which are the same or different from each other, for example, frill group, thienyl group, pyrrolyl group, pyridyl group, piperidino group. , Piperidyl group, quinolyl group, isooxazolyl group and other 5-membered to 10-membered heterocyclic groups. The heterocyclic group includes, for example, a methyl group, a trifluoromethyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, and the like. aliphatic hydrocarbon groups such as tert-pentyl group, 1-methylpentyl group, 2-methylpentyl group, hexyl group, isohexyl group, 5-methylhexyl group, methoxycarbonyl group, trifluoromethoxycarbonyl group, ethoxycarbonyl group, Ester groups such as propoxycarbonyl group, acetoxy group, trifluoroacetoxy group, benzoyloxy group, phenyl group, biphenylyl group, o-tolyl group, m-tolyl group, p-tolyl group, o-cumenyl group, m-cumenyl group , P-Cumenyl group, xsilyl group, mesityl group, styryl group, cinnamoyl group, naphthyl group and other aromatic hydrocarbon groups, and one or more substituents such as carboxy group, hydroxy group, cyano group and nitro group. You may have.

The azo compounds constituting the azo-based organic metal complex represented by the general formula are carbonyl in the molecule with a diazonium salt having R21, R22 or R23, R24 corresponding to the general formula according to a conventional method. It can be obtained by reacting with a heterocyclic compound having an active methylene group adjacent to the group, for example, an isooxazolone compound, an oxazolone compound, a thionaphthene compound, a pyrazolone compound, a barbitulic acid compound, a hydantin compound, a rodanine compound and the like. .. Y21 and Y22 represent heteroatoms that are the same as or different from each other selected from the elements of Group 16 in the periodic table, such as oxygen atom, sulfur atom, selenium atom, and tellurium atom.

The azo metal complex represented by the general formula is usually used in the form of a metal complex in which one or more of them are coordinated to a metal (central atom). Examples of metal elements that serve as central atoms include scandium, yttrium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, technetium, renium, iron, ruthenium, osmium, cobalt, and rhodium. , Iridium, nickel, palladium, platinum, copper, silver, gold, zinc, osmium, mercury and the like, and cobalt is particularly preferable.

FIG. 2A shows the change in the absorbance of the irradiated laser beam with respect to the wavelength of the dye A. FIG. 2B shows the change in the absorbance of the irradiated laser beam with respect to the wavelength of the dye B. FIG. 2 (c) shows the change in the absorbance of the irradiated laser beam with respect to the wavelength of the dye C.

Further, FIG. 3A shows the change in the absorbance of the irradiated laser beam with respect to the wavelength of the dye D. FIG. 3 (b) shows the change in the absorbance of the irradiated laser light with respect to the wavelength in the anion portion of the dye D.

As is clear from the characteristics shown in FIGS. 2 and 3, the maximum absorption wavelength region of each of the dyes A to D is shifted to a longer wavelength side than the recording wavelength (405 nm). The write-once optical disk described in this embodiment contains an organic dye having the above-mentioned characteristics in the recording film, and has a higher light reflectance after laser light irradiation than the light reflectance before laser light irradiation. By configuring it to have so-called L to H characteristics, even if short-wavelength laser light such as blue laser light is used, storage durability, reproduction signal SN ratio, bit error rate, etc. It is possible to record and reproduce information with high density and sufficiently practical level of performance.

That is, in this write-once optical disk, since the maximum absorption wavelength of the recording film containing the organic dye is on the longer wavelength side than the wavelength of the recording laser light, the absorption of short wavelength light such as ultraviolet rays can be suppressed to a small value. , Excellent optical stability and high reliability of information recording and reproduction.

Further, since the light reflectance is low at the time of information recording, cross light due to reflection diffusion does not occur. Therefore, even when the information is recorded on the adjacent track, the reproduced signal SN ratio and the bit error rate Deterioration can be reduced. Further, the contrast and resolution of the recording mark can be maintained with high quality even with respect to heat, and the recording sensitivity design can be easily performed.

In order to obtain good L to H characteristics, it is desirable that the absorbance at the recording wavelength (405 nm) is 0.3 or more. More preferably, it is 0.4 or more.

Here, the shape of the groove, which is the recording / playback track of the write-once optical disc, greatly affects the recording / playback characteristics. As a result of diligent research by the inventors of this invention, it was found that the relationship between the width of the groove and the width of the land is particularly important.

That is, it was found that when the groove width is equal to or narrower than the land width, the reproduction signal SN ratio and the bit error rate of the recorded information tend to deteriorate. That is, it was found that better recording / playback characteristics can be obtained when the groove width is wider than the land width.

In general, in order to record information on a writable optical disc, various address information such as a track number, a sector number, a segment number, and an ECC (Error Checking and Correcting) block address number are recorded on the optical disc in advance. It is necessary to keep it.

As a means for recording such address information, it can be realized by wobble (meandering) the groove in the radial direction of the optical disc. That is, the recording of address information by wobble is a means of modulating the wobble frequency corresponding to the address information, a means of modulating the wobble amplitude corresponding to the address information, a means of modulating the wobble phase corresponding to the address information, and a wobble. This can be realized by means for modulating the polarity reversal interval of the above in correspondence with the address information. Further, not only the wobble groove but also the means of using the height change of the land together, that is, the means of embedding the prepit in the land can be used.

It was also found that the wobble amplitude of the groove, the depth of the groove, and the like also have a great influence on the characteristics of recording and reproduction.

Hereinafter, the above-described embodiment will be described based on the examples. First, create a disc stamper for a high-density R disc by the following procedure. That is, as shown in FIG. 4A, a silicon wafer 11 for semiconductor manufacturing, which is formed in a disk shape having a diameter of 200 mm and a thickness of 0.725 mm, is prepared.

The silicon wafer 11 is immersed in a mixed solution of hot concentrated sulfuric acid and hydrogen peroxide solution (liquid temperature 100 ° C.) for 5 minutes. Next, the silicon wafer 11 is rinsed by immersing it in ultrapure water, ultrasonically cleaned, then immersed in a warm ultrapure water tank at 70 ° C. and gradually pulled up to dry.

Then, as shown in FIG. 4B, an electron beam resist film 12 is formed on the surface of the silicon wafer 11. The electron beam resist film 12 is agitated by mixing an electron beam resist (ZEP520A7 manufactured by Nippon Zeon) with a weight of 100% of anisole solvent (ZEP-A manufactured by Nippon Zeon) on the surface of a silicon wafer 11 by a weight of 86.2%. It is formed by spin-coating the resist solution.

The spin coating conditions are as follows: the silicon wafer 11 is vacuum-chucked on the spin table, the resist solution 12 is dropped on the center of the silicon wafer 11 through a 0.1 micron filter while the rotation of the spin table is stopped, and then the silicon wafer 11 is spun at 2500 rpm. Rotate the table.

Then, as shown in FIG. 4 (c), the groove 13 is formed on the electron beam resist film 12. In this method, the silicon wafer 11 coated with the electron beam resist film 12 is placed in a vacuum chamber of an electron beam cutting machine, and 10^-5After exhausting to the Pa stand, the silicon wafer 11 is rotated, the electron beam resist film 12 is irradiated with an electron beam from the electron gun 14, and a concentric or spiral groove pattern is recorded by the electron beam.

The recording conditions for the groove pattern are an electron beam acceleration voltage of 50 kV, a beam current of 120 nA, a beam diameter of 110 nm, and a recording line velocity of 1.1 m / sec. Further, the recording area of the groove 13 is a range in which the radius of the silicon wafer 11 is 23 mm to 59 mm.

Then, the silicon wafer 11 after the groove 13 is recorded is taken out from the vacuum chamber of the electron beam cutting machine and dipped in the organic developer 16 in the immersion tank 15 as shown in FIG. 4 (d) for dip development. The resist pattern of the groove 13 is formed by performing the above.

Next, as shown in FIG. 4 (e), a Ni thin film 17 is formed on the surface of the resist pattern and made conductive by performing DC sputtering of the Ni film.

Then, as shown in FIG. 5A, Ni electroplating is performed on the Ni thin film 17 to form a Ni plating layer 18 having a thickness of 247 μm. Then, as shown in FIG. 5 (b), the Ni plating layer 18 is peeled off, spin-cleaned, and then the residual resist on the surface is peeled off by oxygen RIE. After that, as shown in FIG. 5 (c), a protective film is applied to the Ni plating layer 18, the back surface side is polished, and the inner and outer diameters are processed to prepare the disc stamper 19.

Next, a write-once optical disc is created using this disc stamper 19. That is, as shown in FIG. 6 (a), by injection molding with the injection molding apparatus SD40 manufactured by Sumitomo Heavy Industries, Ltd. using the disc stamper 19, the thickness is 0.6 mm as shown in FIG. 6 (b). Duplicate the transparent disk substrate 20 made of polycarbonate. As a matter of course, a groove 21 is formed on the disk substrate 20.

After that, as shown in FIG. 6 (c), a groove 21 of the disk substrate 20 is formed by using a dispenser 22 having a nozzle diameter of 21 G to form an organic dye solution 23, which will be described later, in which an organic dye is dissolved in a solvent. Hanging on the surface. Next, by controlling the rotation of the disk substrate 20, as shown in FIG. 6D, the organic dye solution 23 fills the groove 21 to form the recording film 24.

As for the spin coating condition of the recording film 24, first, the disk substrate 20 is rotationally driven from a stopped state to 300 rpm in 1 second, and while the disk substrate 20 is held in this state for 8 seconds, the organic dye solution 23 is applied by the dispenser 22. Next, the rotation speed of the disk substrate 20 is increased to 1800 rpm in 2 seconds, and the disk substrate 20 is held in this state for 15 seconds. After that, the rotation speed of the disk substrate 20 is increased to 3000 rpm in 2 seconds, and the state is held for 3 seconds.

By controlling the rotation speed in the second stage, the film thickness of the recording film 24 can be controlled. That is, if the rotation speed in the second stage is reduced, the film thickness of the recording film 24 can be increased.

Next, the disk substrate 20 coated with the recording film 24 is baked at 80 ° C. for 30 minutes in a clean oven, and a 100 nm metal film 25 is sputtered on the recording film 24 as shown in FIG. 6 (e). To do. As the metal film 25, an Ag alloy containing 1% AgND and 1% Cu is used, but sterling silver can also be used.

Then, as shown in FIG. 6 (f), an ultraviolet curable resin 26 is spin-coated on the metal film 25, and a disk substrate 27 made of polycarbonate having a thickness of 0.6 mm is attached to record an organic dye. The write-once optical disk (R disk) 28 included in 24 will be created.

Here, as shown in FIG. 8, the write-once optical disk 28 created as described above is for recording / playback by the optical head 29 from the surface of the disk substrate 20 opposite to the surface coated with the recording film 24. Laser light is incident.

In this case, the bottom surface 21a of the groove 21 formed on the disk substrate 20 and the land 30 sandwiched between the adjacent grooves 21 serve as an information recording track. The recording track composed of the bottom surface 21a of the groove 21 is referred to as a groove track Gt, and the recording track composed of the land 30 is referred to as a land track Lt.

The difference in height between the land track Lt surface and the groove track Gt surface is referred to as the groove depth Gh. Furthermore, the width of the groove track Gt seen at a height of about 1/2 of the groove depth Gh is called the groove width Gw, and the width of the land track Lt seen at a height of about 1/2 of the groove depth Gh is called the land width. Called Lw.

Further, as described above, the groove track Gt is wobbled to record various address information. FIG. 9 (a) shows a case where adjacent groove tracks Gt are in phase, and FIG. 9 (b) shows a case where adjacent groove tracks Gt are out of phase. Depending on the region of the write-once optical disc 28, the adjacent groove tracks Gt will have various phase differences.

Next, the production of the above-mentioned organic dye solution 23 will be described. As the organic dye solution 23, a solution having a solution concentration of 1.2% obtained by dissolving 1.2 g of organic dye powder in 100 ml of TFP by weight is used. The condition for dissolution in the solvent is to put the dye powder in the solvent and apply ultrasonic waves for 30 minutes.

As organic dyes, in addition to the above-mentioned four types of dyes A to D, seven types of mixed dyes F to L are prepared by mixing two or more of these dyes.

The mixed dye F is a dye D to which 5% of the dye B is added, that is, a mixture of 1 g of the dye D and 0.05 g of the dye B.

The mixed dye G is a dye D mixed with a monomethine cyanine dye (anion part azometal complex 3) as a dye E at a ratio of 7: 3 (= D: E), and further added with a dye B of 5%. That is, the dye B was mixed at a ratio of 0.05 g to 1 g of the dye at which the dyes D and E were mixed at a ratio of 7: 3.

The mixed dye H is a mixture of dye D and dye A at a ratio of 1: 1 (= D: A).

The mixed dye I is obtained by adding 10% of the dye B to the dye D, that is, a mixture of the dye B at a ratio of 0.10 g to 1 g of the dye D.

The mixed dye J is obtained by adding 15% of the dye B to the dye D, that is, a mixture of the dye B at a ratio of 0.15 g to 1 g of the dye D.

The mixed dye K is obtained by adding the azo metal complex 1 of the anion part to the dye D, increasing the anion ratio to dye part: anion part = 1: 1.5, and further adding 15% of the dye B.

The mixed dye L is obtained by adding the azo metal complex 1 of the anion portion to the dye D, further increasing the anion ratio of the dye portion: anion portion = 1: 2.0, and further adding 15% of the dye B.

FIGS. 10 (a) to 10 (g) show changes in the absorbance of the irradiated laser light with respect to the wavelength of the mixed dyes F to L, respectively. In all of the mixed dyes F to L, the maximum absorption wavelength region is shifted to the longer wavelength side than the recording wavelength (405 nm), and the absorbance at the recording wavelength (405 nm) exists in the vicinity of approximately 0.4.

Using the 11 types of organic dyes A to D and F to L described above, write-once optical discs 28 are prepared by the above methods, and the evaluation test is carried out by recording and reproducing them on the groove track Gt. .. As the evaluation device, a pulse tech optical disc evaluation device is used.

The test conditions are that the objective lens aperture ratio NA of the optical head 29 is 0.65, the wavelength of the laser beam for recording and reproduction is 405 nm, and the linear velocity during recording and reproduction is 6.61 m / sec. The recorded signal is 8-12 modulated random data, and is a waveform recorded with a constant recording power and two types of bias powers 1 and 2, as shown in FIG.

The track pitch is 400 nm, the groove width Gw is set to 1.1 for the land width Lw 1, the wobble amplitude of the groove track Gt is set to 14 nm, and the groove depth Gh is set to 90 nm. Wobble phase modulation is used to record address information by wobble.

Here, three types of evaluation characteristics are measured: the carrier noise ratio CNR of the reproduced signal, the SN ratio PRSNR (partial response signal to noise ratio) at the time of partial response, and the predicted bit error rate SbER (simulated bit error rate). ing. The definition and measurement method of PRSNR are described in the book that can be purchased from DVD Format Logo Licensing Co., Ltd. This is the Annex H part of DVD Specifications for High Density Read-Only Disc PART 1 Physical Specifications Version 0.9. The PRS NR is preferably 15 or more. The definition and measurement method of SbER are described in the book available from DVD Format Logo Licensing Co., Ltd. This is the Annex H part of DVD Specifications for High Density Read-Only Disc PART 1 Physical Specifications Version 0.9. SbER is 5.0 × 10^-5It is preferable to make the following. In addition, PRSNR and SbER are measured with information recorded on adjacent tracks.

FIG. 12 shows the measurement results of each write-once optical disc 28 using the dyes A to D and F to L. Judging from the measurement results shown in FIG. 12, it can be seen that the write-once optical discs 28 using the dyes B and C are not suitable for practical use because the measurement results of CNR, PRSNR, and SbER are not sufficient.

On the other hand, the write-once optical discs 28 using the dyes A, D, F, G, H, I, J, K, and L have obtained good measurement results. The measurement result of the write-once optical disc 28 using the dye A is also good, but the measurement result of the write-once optical disc 28 using the dye D is particularly good. Furthermore, the measurement results of each write-once optical disc 28 using the dyes F, I, J, K, and L are excellent.

Next, a test is conducted to evaluate the degree of deterioration due to repeated reproduction for each write-once optical disc 28 using dyes D, F, G, H, I, J, K, and L having good measurement results. .. That is, with a laser power for reproduction of 0.8 mW, reproduction is performed 10,000 times, and the degree of deterioration of PRSNR and SbER is measured.

FIG. 13 shows the measurement results of each write-once optical disc 28 using the dyes D, F, G, H, I, J, K, and L. It can be seen that the write-once optical disc 28 using the dye G does not have good measurement results of PRSNR and SbER. Compared with the measurement result of the write-once optical disc 28 using the dye D, the measurement result of each write-once optical disc 28 using the dyes F, H, I, J, K and L is better.

Above all, the measurement results of the write-once optical discs 28 using the dyes J, K, and L are particularly good, and the measurement results of the write-once optical discs 28 using the dye L are the best.

From the above, it can be seen that as the organic dye material used for the recording film 24, a material having a styryl dye or a monomethicyanine dye in the dye portion and an azo metal complex in the anion portion is preferable.

It can also be seen that a mixture of the styryl pigment and the monomethicyanine pigment is also good. Furthermore, it can be seen that the one to which the nickel metal complex is added is excellent. Further, it can be seen that the one in which the mixing ratio of the azo metal complex in the anion portion is increased is excellent in the regenerated light durability.

Next, a disc stamper 19 in which the groove width Gw is changed to 0.7 to 1.8 with respect to the land width Lw 1 is created, and the write-once optical disc 28 using the dye J is used using this disc stamper 19. An evaluation test is carried out by creating and recording / reproducing the groove track Gt.

Three types of evaluation characteristics are measured: light reflectance, SbER, and PRSNR. The definition and measurement method of light reflectance is described in a book that can be purchased from DVD Format Logo Licensing Co., Ltd. DVD Specifications for High Density Read-Only Disc PART 1 This is the Annex D part of Physical Specifications Version 0.9. The reflectance is 16% or more, more preferably 18% or more, and preferably 32% or less.

FIG. 14 shows the measurement result of the light reflectance with respect to the groove width Gw. FIG. 15 shows the measurement result of SbER with respect to the groove width Gw. FIG. 16 shows the measurement result of PRSNR with respect to the groove width Gw. In the measurement result of PRSNR shown in FIG. 16, the solid line indicates the state in which the information is recorded in the adjacent track, and the dotted line indicates the state in which the information is not recorded in the adjacent track.

Here, it is desirable that the light reflectance is approximately 16.0% or more, more preferably 18.0% or more, and 32.0% or less. For SbER, 5.0 × 10^-5It is said that it is good to do the following. For PRSNR, it is better to set it to 15 or more.

Therefore, when these conditions are applied to FIGS. 14 to 16, it is possible to obtain good characteristics that the groove width Gw is in the range of 1.05 to 1.5 when the land width Lw is 1. You can see that.

Further, FIGS. 14 to 16 show the characteristics of the write-once optical disc 28 using the dye J when the groove width Gw is changed, but other dyes D, F, G, H, I, For each write-once optical disc 28 using K and L, the results of measuring the light reflectance, SbER, and PRSNR when the groove width Gw was changed showed that the groove width was equal to the land width Lw 1. Good results are obtained when Gw is in the range of "1.05 to 1.5".

The present invention is not limited to the above-described embodiment as it is, and at the implementation stage, the constituent elements can be variously modified and embodied within a range that does not deviate from the gist thereof. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the above-described embodiment. For example, some components may be deleted from all the components shown in the embodiment. Further, the components according to different embodiments may be combined as appropriate.

Further, when the management information (system read-in) is inserted into a certain part of the disc, for example, in the innermost peripheral region, this low-to-high recording disc can exert the maximum effect. The management information forms a pit row on the disk board similar to the ROM disk board. Management of whether the disc is play-only, write-once, or rewritable, what the recording / playback wavelength is, whether it is low-to-high or high-to-low, and what the recorded data capacity is. Information is recorded as a pit row. The track pitch of the groove in the recording data area is selected to be 400 nm or 320 to 300 nm, but the track pitch of the pit row in this management information area is formed wider than that, and the data bit pitch of the pit is also wider than that of the recording data area. It is good that the larger the value, the easier the reproduction and the easier the determination of the management information. Figures 17 (a) and 17 (b) show the playback signal waveform in the system read-in area of the high-to-low recording disc and the playback signal waveform after recording data in the recording data area (area where the groove is formed). The comparison between the reproduced signal waveform in the system read-in area of the low-to-high recording disc and the reproduced signal waveform after recording the data in the recorded data area (area in which the groove is formed) is shown. As is clear from this figure, it can be seen that the low-to-high disk has the same signal level position in the system read-in area and the data area, and is easier to play back in the drive.

<figref num="1">The figure which shows the embodiment of this invention and shows 4 examples of the organic dye material to be contained in a recording film.</figref><figref num="2">A characteristic diagram showing three of the organic dye materials to explain the change in absorbance with respect to the wavelength of the laser beam.</figref><figref num="3">A characteristic diagram showing the remaining one of the organic dye materials to explain the change in absorbance with respect to the wavelength of the laser beam.</figref><figref num="4">The figure shown for demonstrating a part of the method of making a disk stamper for making a write-once optical disk in the same embodiment.</figref><figref num="5">The figure shown for demonstrating the rest of the method of making the disk stamper.</figref><figref num="6">The figure shown for demonstrating the method of making the write-once type optical disk.</figref><figref num="7">The figure which shows in order to explain the spin coating condition of the organic dye solution in the method of making the postscript type optical disk.</figref><figref num="8">The figure which shows in order to explain the relationship between a groove and a land in the write-once type optical disk.</figref><figref num="9">The figure which shows to explain the wobble of the groove track in the write-once type optical disk.</figref><figref num="10">A characteristic diagram showing seven examples of other organic dye materials contained in the recording film to explain the change in absorbance with respect to the wavelength of laser light.</figref><figref num="11">The waveform diagram which shows an example of the signal to be recorded in order to perform the evaluation test of the recording / reproduction evaluation on the write-once type optical disk.</figref><figref num="12">The figure which shows 11 examples of the organic dye material for demonstrating the measurement result which carried out the evaluation test of the write-once optical disk.</figref><figref num="13">The figure which shows 8 examples of the organic dye material for demonstrating the measurement result which performed the reproduction durability test of the write-once optical disk.</figref><figref num="14">The characteristic diagram which shows for explaining the relation | relationship between the groove width and the light reflectance of the write-once type optical disk.</figref><figref num="15">The characteristic diagram shown to explain the relation between the groove width of the write-once optical disk and the predicted bit error rate.</figref><figref num="16">The characteristic diagram shown to explain the relationship between the groove width of the write-once optical disc and the SN ratio at the time of partial response.</figref><figref num="17">The figure shown for demonstrating the reproduction signal waveform of a high-to-Low disc and a Low-to-High disc.</figref>

Code description

11 ... Silicon wafer, 12 ... Electron beam resist film, 13 ... Groove, 14 ... Electron gun, 15 ... Immersion tank, 16 ... Organic developer, 17 ... Ni thin film , 18 ... Ni Plating Layer, 19 ... Disc Stamper, 20 ... Disc Substrate, 21 ... Groove, 22 ... Dispenser, 23 ... Organic Dye Solution, 24 ... Recording Film, 25 ... metal film, 26 ... UV curable resin, 27 ... disk substrate, 28 ... write-once optical disk, 29 ... optical head, 30 ... land.