JP2005050497A - Optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical recording medium of a single-sided two-layer recording and reproducing type wherein satisfactory recording signal characteristics can be obtained from two information recording layers. <P>SOLUTION: In the optical recording medium, optically readable information can be recorded and/or reproduced. A first substrate formed by laminating at least a first recording layer composed of an organic coloring matter and a first translucent reflection layer and a second substrate formed by laminating at least a second reflection layer and a second recording layer composed of an organic coloring matter are provided via a transparent intermediate layer so as to be positioned on outer sides thereof. The first reflection layer is essentially composed of one of Au, Ag and Cu, composed of an alloy containing at least one selected from a group composed of Au, Ag, Cu, Al, Ti, V, Cr, Ni, Nd, Mg, Pd, Zr, Pt, Ta, W, Si, Zn and In and has a light transmittance of 30 to 60% and a light reflectance of 15 to 35%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical recording medium that records and reproduces information by irradiating a light beam, and particularly to a dual-layer DVD (Digital Video Disc or Digital Versatile Disc) having two write-once information recording layers. It is.

In addition to optical recording media such as read-only DVD-ROMs, recordable DVDs (DVD + RW, DVD + R, DVD-R, DVD-RW, DVD-RAM, etc.) have been put into practical use. These DVD + R, DVD + RW, etc. are positioned on the extension of conventional recordable CD-R, CD-RW (recordable compact disc) technology, and are recorded to ensure playback compatibility with playback-only DVDs. The density (track pitch, signal mark length) and substrate thickness are designed to meet the DVD conditions from the CD conditions.
For example, in the case of DVD + R, an information recording substrate having an optical recording layer provided by spin coating a dye on a substrate and a metal reflective layer behind it is formed in the same shape via a bonding material as in CD-R. A configuration in which the substrate is bonded is adopted. In this case, a dye material is used for the optical recording layer. CD-R is characterized by having a high reflectivity (65%) that satisfies the CD standard. In order to obtain a high reflectivity in the above configuration, the light absorption layer has a recording / reproducing light wavelength. This is because a specific complex refractive index needs to be satisfied, and the light absorption characteristics of the dye are suitable. The same applies to DVDs.

  By the way, a read-only DVD has been proposed that has two information recording layers in order to increase the recording capacity. FIG. 1 is a sectional view showing the structure of a DVD having such two information recording layers. The board | substrate 1 and the board | substrate 2 are bonded together by pinching | interposing the transparent intermediate | middle layer 5 formed with the ultraviolet curing resin. A translucent layer 3 that is a first information recording layer on which an uneven recording mark is formed is formed on the inner surface of the substrate 1, and a second information recording layer is formed on the inner surface of the substrate 2. A reflective layer 4 is formed. The semi-transmissive layer 3 is formed using a dielectric film or a thin metal film, and the reflective layer 4 is formed from a metal film or the like. Information recorded in each information recording layer is read by the effect of reflecting / interfering the reproduction laser beam. Since signals are read from the two information recording layers, a maximum storage capacity of about 8.5 GB can be obtained. Moreover, the thickness of the board | substrate 1 and the thickness of the board | substrate 2 are each 0.6 mm, and the thickness of the transparent intermediate | middle layer 5 is about 40 micrometers. The transflective layer 3 is formed so that the reflectance thereof is about 30%, and the laser light irradiated for reproducing the information of the second information recording layer is about the total light amount in the first information recording layer. After 30% of the light is reflected and attenuated, it is reflected by the reflective layer 4 as the second information recording layer, further attenuated by the semi-transmissive layer 3, and then leaves the disc. The signal of each information recording layer can be reproduced by narrowing the laser light, which is the reproduction light, so that the focal point comes on the first or second information recording layer and detecting the reflected light. In the case of DVD, the laser beam wavelength used for recording / reproduction is about 650 nm.

  However, the above recordable DVDs, that is, DVD + R, DVD-R, DVD-RW, DVD + RW, and the like have only one information recording layer that can be read from one side, and in order to obtain a larger storage capacity with these optical information media. It was necessary to reproduce from both sides. The reason for this is that, since a single-sided dual-layer recording / reproducing type optical recording medium has two information recording layers, when a signal is recorded by irradiating a writing laser beam with focus on the information recording layer from the optical pickup. Since the first information recording layer attenuates the laser beam, there is a problem that the light absorption and the light reflection necessary for the recording of the second information recording layer cannot be achieved at the same time.

As a technique for addressing the above problem, Patent Document 1 discloses a single-sided dual-layer recording / reproducing type optical recording medium having an information layer having a translucent reflective film and an information layer having a reflective film, the translucent reflective film A material using an alloy containing Ag as a main component and adding Au or the like is disclosed. However, there is no specific explanation about the medium using the dye recording layer. Naturally, when the semi-transmissive first reflective film (corresponding to the semi-transparent reflective film), which is the subject of the present invention, is thinned, the resin layer There is no description or suggestion that this problem must be solved in order to obtain a practical medium, since the components react with the dye recording layer and degrade the dye recording layer.
Japanese Patent Application Laid-Open No. 2004-228688 also discloses a light having a configuration in which two information recording layers made of an organic dye can be written from one side of an optical recording medium during recording and the two information recording layers are read from one side of the optical recording medium during reproduction. Although a recording medium is disclosed, as a specific example, the conventional substrate surface incident recording structure and the recording film surface incident structure are used in a configuration in which two kinds of substrates are pasted. Cannot solve the problem of absorption reflection. Further, there is no description at all about the problems of the present invention relating to the deterioration of the dye recording layer and the means for solving the problems.

JP 2002-140838 A JP 11-66622 A

  An object of the present invention is to provide a single-sided dual-layer recording / reproducing type optical recording medium that solves the above-mentioned problems and that can obtain good recording signal characteristics from two information recording layers.

As a result of intensive studies, the present inventors have found an optical recording medium that meets the above-mentioned purpose. That is, the said subject is solved by the following invention of 1) -7) (henceforth this invention 1-7).
1) An optical recording medium capable of recording and / or reproducing optically readable information, and at least a first substrate on which a first recording layer made of an organic dye and a semi-transmissive first reflective layer are laminated A second substrate on which at least a second reflective layer and a second recording layer made of an organic dye are laminated is provided so that both substrates are located outside via a transparent intermediate layer, and the first reflective layer is One of Au, Ag and Cu as the main component, selected from Au, Ag, Cu, Al, Ti, V, Cr, Ni, Nd, Mg, Pd, Zr, Pt, Ta, W, Si, Zn, In An optical recording medium comprising the above-described alloy containing at least one kind, wherein the reflective layer has a light transmittance of 30 to 60% and a light reflectance of 15 to 35%.
2) An optical recording medium capable of recording and / or reproducing optically readable information, and at least a first substrate on which a first recording layer made of an organic dye and a semi-transmissive first reflective layer are laminated. A second substrate on which at least a second reflective layer and a second recording layer made of an organic dye are laminated is provided so that both substrates are located outside via a transparent intermediate layer, and the first reflective layer is One of Au, Ag and Cu as the main component, selected from Au, Ag, Cu, Al, Ti, V, Cr, Ni, Nd, Mg, Pd, Zr, Pt, Ta, W, Si, Zn, In The alloy containing at least one selected from the above and a metal or metalloid oxide and / or nitride mixture, the light transmittance of the reflective layer is 30 to 60%, and the light reflectance is 15 to 35. %, An optical recording medium.
3) An optical recording medium capable of recording and / or reproducing optically readable information, and at least a first substrate on which a first recording layer made of an organic dye and a semi-transmissive first reflective layer are laminated A second substrate on which at least a second reflective layer and a second recording layer made of an organic dye are laminated is provided so that both substrates are located outside via a transparent intermediate layer, and the first reflective layer is It is made of a mixture of at least two kinds selected from metal or metalloid simple substance, oxide, and nitride, and the light transmittance of the reflective layer is 30 to 60% and the light reflectance is 15 to 35%. A characteristic optical recording medium.
4) An optical recording medium capable of recording and / or reproducing optically readable information, and at least a first substrate on which a first recording layer made of an organic dye and a semi-transmissive first reflective layer are laminated. A second substrate on which at least a second reflective layer and a second recording layer made of an organic dye are laminated is provided so that both substrates are located outside via a transparent intermediate layer, and the first reflective layer is a metal Alternatively, it is made of a single metal, the light transmittance of the reflective layer is 30 to 60% and the light reflectance is 15 to 35%, and the auxiliary layer is made of an oxide or nitride of metal or metalloid. A characteristic optical recording medium.
5) An optical recording medium capable of recording and / or reproducing optically readable information, and at least a first substrate on which a first recording layer made of an organic dye and a semi-transmissive first reflective layer are laminated A second substrate on which at least a second reflective layer and a second recording layer made of an organic dye are laminated is provided so that both substrates are located outside via a transparent intermediate layer, and the first reflective layer is One of Au, Ag and Cu as the main component, selected from Au, Ag, Cu, Al, Ti, V, Cr, Ni, Nd, Mg, Pd, Zr, Pt, Ta, W, Si, Zn, In The reflective layer has a light transmittance of 30 to 60% and a light reflectance of 15 to 35%, and the auxiliary layer is a metal or metalloid oxide or nitride. An optical recording medium comprising:
6) The metal or metalloid used for the first reflective layer is any one of Au, Ag, Cu, Al, Ti, Cr, Mg, Ta, W, Si, Zr, and the first reflective layer or the auxiliary layer The metal or metalloid oxide used is at least one of aluminum oxide, titanium oxide, chromium oxide, magnesium oxide, zirconium oxide, tantalum oxide, silicon oxide, calcium oxide, tin oxide, indium oxide, and indium tin oxide. The optical recording medium according to any one of 2) to 5), comprising:
7) The metal or metalloid used in the first reflective layer is any one of Au, Ag, Cu, Al, Ti, Cr, Mg, Ta, W, Si, and Zr, and the first reflective layer or the auxiliary layer The optical recording medium according to any one of 2) to 5), wherein the metal or metalloid nitride used contains at least one of aluminum nitride, titanium nitride, silicon nitride, and zirconium nitride.

Hereinafter, the present invention will be described in detail.
As described above, in the prior art, since the first information recording layer attenuates laser light, it is difficult to achieve both light absorption and light reflection necessary for recording on the second information recording layer. As a means for solving this problem, it is conceivable to make the semi-transmissive first reflective layer thin. In that case, a transparent intermediate layer provided in contact with the first reflective layer, an overcoat layer, etc. There arises a new problem that the component of the resin layer reacts with the organic dye of the first recording layer through the first reflective layer and deteriorates the characteristics of the first recording layer. The present invention solves these problems by devising the material of the semi-transmissive first reflective layer and the configuration of the layer in contact with the first reflective layer.
That is, in the first aspect of the invention, by using an alloy having a specific composition as the material of the first reflective layer, a thin film with fine crystal grains and excellent corrosion resistance can be obtained. Reaction with organic dyes can be prevented. Furthermore, in the present inventions 2 to 5, by using a mixture of specific materials or laminating an auxiliary layer, the reaction between the components of the resin layer and the organic dye of the first recording layer is suppressed, and the first recording is performed. Degradation of the layer characteristics can be prevented.

An example of the layer structure of the optical recording medium of the present invention is shown in FIG.
A first substrate having a first information layer in which a first recording layer made of an organic dye and a semi-transmissive first reflective layer are sequentially laminated on a surface having a light guide groove, and a second substrate on a surface having a light guide groove. A reflective layer, a second recording layer made of an organic dye, and a second substrate having a second information layer in which a barrier layer is sequentially laminated, with the recording layer facing inward so that the laminated films face each other through a transparent intermediate layer The optical recording medium performs recording and reproduction of signal information on the first and second recording layers by bonding and irradiating laser light from the first substrate side.
The first reflective layer is formed of an alloy, formed of a mixture of an alloy and a metal or metalloid oxide and / or nitride, or at least selected from a metal or metalloid simple substance, oxide, or nitride. By forming with two types of mixture, an optical recording medium with few defects and high reliability can be obtained.

  The semi-transmissive first reflective layer needs to have a light transmittance of 30 to 60% and a light reflectance of 15 to 35% with respect to the recording / reproducing laser beam. Outside this numerical range, the light transmittance is too low to make recording / reproduction of the second recording layer difficult, or the light reflectance is too low to make recording / reproduction of the first recording layer difficult. Playback becomes difficult. In order to make the above numerical range, the film thickness may be selected in accordance with a material appropriately selected from the materials described later. The film thickness is usually 5 to 30 nm. If the thickness is less than 5 nm, it is difficult to prevent deterioration of the characteristics of the first recording layer, which is not preferable. If the thickness exceeds 30 nm, it is difficult to satisfy the light transmittance.

The first information layer has the same configuration as a conventional single recording layer medium (DVD + R, DVD-R, etc.) in which the first recording layer and the first reflective layer formed on the first substrate are bonded to the second substrate. By doing so, the reflectance and the recording signal modulation degree (contrast) are obtained by the multiple interference effect of both the upper and lower interfaces of the first recording layer and the substrate deformation at the time of mark formation.
Further, for the second information layer having a configuration different from that of the first information layer, the reflectance and the recording signal modulation degree (contrast) are obtained by the light absorption characteristics of the second recording layer made of the substrate groove shape and the organic dye, It is preferable to arrange the recording mark shape by disposing the second recording layer between the inorganic layers (second reflective layer and barrier layer) which are not easily deformed.
In order to obtain the above effect, the thickness of the second recording layer is preferably 1.5 to 2.5 times the thickness of the first recording layer. When the film thickness ratio of the recording layer is out of this range, the ease of spreading of the recording mark differs, and it becomes difficult to record the two recording layers with the same recording strategy (light emission pulse pattern of recording laser). The method for forming a recording layer made of an organic dye is generally a method of spin-coating a dye dissolved in a coating solvent. When a film is formed on a substrate on which guide grooves are formed, a groove portion and a groove portion are formed. Causes a difference in pigment film thickness.

As shown in FIG. 2, the groove shapes formed in the first substrate and the second substrate are not the same. In the case of 4.7 GB, 0.74 μm pitch DVD + R, and DVD-R, the groove shape of the first substrate is preferably groove depth: 1000 to 2000 mm and groove width (bottom width): 0.2 to 0.3 μm. In the case of spin coating, since the groove tends to be filled with a dye, the interface shape between the first recording layer and the first reflective layer is determined by this filling amount and the substrate groove shape, so that the interface reflection is reduced. The above range is suitable for use.
On the other hand, the groove shape of the second substrate is preferably groove depth: 200 to 600 mm and groove width: 0.2 to 0.4 μm. As shown in FIG. 2, since the interface shape between the second recording layer and the second reflection layer is determined by the substrate groove shape, the above range is suitable for utilizing the interface reflection.
If the groove depth is deeper than the groove shape range in both the first substrate and the second substrate, the reflectivity is likely to decrease. If the groove depth is shallower than the groove shape range or the groove width is deviated, the shape of the formed recording mark is difficult to obtain and jitter is likely to increase.

In DVD + R, in order to achieve reproduction compatibility with DVD-ROM, a tracking guide groove called groove forms a meander called wobble, and the wobble cycle is 32 times the data clock, that is, about It is 818 kHz. The relationship between this wobble and data sector is that 93 out of 26 EFM Sync Frames (8-14 modulation / sync frame) in one data sector correspond to 2 EFM Sync Frames. . Of the 93 wobbles, 8 are composed of a phase modulation part called ADIP Unit (address in pregroove unit) and 85 monotone wobbles, and the sync part of the data sector is the 16th. The relationship is located in the wobble. Further, four ECC addresses (words) are stored in one ECC block (error correction code block), which is an error correction block of data, in a basic unit. That is, one address is included in four data sectors. The ADIP Word is composed of one ADIP Sync Unit (sink unit) and 51 ADIP Data Units (data units). Each Unit corresponds to the 93 wobbles. Of the 51 ADIP Data Units, 1 bit (bit) is reserved, 2 bits to 23 bits are address information ADIP Data Bit, 24 bits to 31 bits are 8 bits auxiliary data for storing various information about the disk, 32 bits to 51 bits The remaining 20 bits up to are configured as parity bits (parity bits) for error correction.
In DVD-R, the pre-format is a continuous groove and CLV shape by wobbled grooves as in DVD + R, but the wobble signal is a single frequency (186 T period) signal without modulation, and the address signal is a land between grooves. A pre-pit system is used.

A preferable dye film thickness is 40 to 1000 mm in the first recording layer (groove), and 600 to 3000 mm in the second recording layer (inter-groove). This is because if the dye film thickness is thinner than this range, it is difficult to obtain the degree of signal modulation (contrast). On the contrary, if the dye film thickness is thick, the mark shapes are difficult to align and jitter is likely to increase.
As an example of the layer structure different from FIG. 2, as shown in FIG. 3 and FIG. 4, the first reflective layer is composed of a single metal or semimetal, or is composed of the same alloy as that of the present invention 1, and the first reflective layer is formed. By laminating an auxiliary layer made of a metal or metalloid oxide or nitride film having a high light transmittance in contact with the first layer, the first layer can be more effectively compared with the case of using only a very thin first reflective layer. The reaction between the organic dye of the recording layer and the resin such as the transparent intermediate layer and the overcoat layer can be suppressed, and the deterioration of the characteristics of the first recording layer can be prevented. By providing the auxiliary layer, an optical recording medium satisfying the problems of the present invention can be obtained even if the first reflective layer is composed of a single metal or semimetal, but the same alloy as that of the present invention 1 is used for the first reflective layer. If is used, the film thickness of the first reflective layer can be set thinner.

Hereinafter, materials used for the optical recording medium of the present invention will be specifically described.
The optical recording medium of the present invention is configured to obtain high reflectivity by the multiple interference effect on both the upper and lower interfaces of a recording layer made of an organic dye, like DVD + R and CD-R, and as a recording layer made of an organic dye. Requires optical characteristics having a large refractive index n and a relatively small absorption k at the recording / reproducing wavelength. Preferred ranges are n> 2, 0.03 <k <0.2. Such optical characteristics can be obtained by utilizing the characteristics of the long wavelength end of the light absorption band of the dye film.
Examples of organic dye materials that can be used for the first and second recording layers include cyanine dyes, phthalocyanine dyes, pyrylium / thiopyrylium dyes, azurenium dyes, squarylium dyes, azo dyes, and formazan chelate dyes. Dyes, Ni, Cr and other metal complex dyes, naphthoquinone dyes / anthraquinone dyes, indophenol dyes, indoaniline dyes, triphenylmethane dyes, triallylmethane dyes, aminium dyes / diimonium dyes, nitroso compounds Can be mentioned.
Furthermore, other 3rd components, for example, a binder, a stabilizer, etc. can be contained as needed. Among them, as a dye compound in which the maximum absorption wavelength of the light absorption spectrum of the film is 580 to 620 nm and desired optical characteristics can be easily obtained at the laser beam wavelength for DVD (about 650 nm), the film forming property and optical characteristics by solvent coating can be obtained. In view of ease of adjustment, at least one dye selected from a phthalocyanine dye, a cyanine dye, an azo dye, and a squarylium dye is preferable.

  The substrate material used in the present invention can be arbitrarily selected from various materials used in conventional information recording media. Examples include acrylic resins such as polymethyl methacrylate, vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers, glasses and ceramics such as epoxy resins, polycarbonate resins, amorphous polyolefins, polyesters, and soda lime glass. Can be mentioned. In particular, polymethyl methacrylate, polycarbonate resin, epoxy resin, amorphous polyolefin, polyester and glass are preferable from the viewpoint of dimensional stability, transparency, flatness, etc., but polycarbonate resin is most preferable from the viewpoint of ease of molding.

  As the semi-transmissive first reflective layer material, a substance having a high reflectivity with respect to the laser light wavelength is preferable, and examples thereof include Au, Ag, Cu, Al, Ti, V, Cr, Ni, Nd, Mg, and Pd. , Zr, Pt, Ta, W, Si, Zn, In, and at least one kind of metal and metalloid can be mentioned. Among them, any one of Au, Ag, and Cu is a main component, Au, 0.1 to 10% by weight of at least one selected from Ag, Cu, Al, Ti, V, Cr, Ni, Nd, Mg, Pd, Zr, Pt, Ta, W, Si, Zn, and In was added. An alloy is preferable, and In is particularly preferable (since it is an alloy, naturally, combinations of Au and Au, Ag and Ag, and Cu and Cu are excluded). By adding 0.1% by weight or more, the crystal grains become fine and a thin film having excellent corrosion resistance is obtained. However, adding more than 10% by weight is not preferable because the reflectance decreases. The base material is most preferably Ag having a high sputter rate, and the additive is particularly preferably Au, Cu, Mg, or In having a small refractive index n and a large absorption coefficient k. Table 1 shows optical constants n and k of various simple substances described in Handbook of Optical Constants of Solids (Academic, 1985), measured wavelengths, and measured photon energy. As shown in FIG. 6, a 65 nm-thick dye recording layer (n, k) = (2.3, 0.04), a semi-transmissive layer on a polycarbonate substrate (n, k) = (1.56, 0). When the transparent intermediate layer (n, k) = (1.56, 0) is stacked and the n, k and film thickness of the semi-transmissive layer are changed to reflectivity of 25%, the transmittance for n and k is The plotted figure is shown. It can be seen from FIG. 6 that the light utilization efficiency is higher as the refractive index of the semi-transmissive reflective layer is smaller. Ag has the smallest n among all elements and has the highest light utilization efficiency. Therefore, it is particularly preferable that the total amount of additives is 5% by weight or less in order not to impair the characteristics.

Moreover, you may provide a 1st overcoat layer for chemical and physical protection of a 1st reflective layer like FIG. 4, FIG. As these materials, ultraviolet curable resin (eg, acrylic resin) or the like can be used.
In the present invention, since the first recording layer made of organic dye and the transparent intermediate layer or first overcoat layer made of resin are in contact with each other through the very thin first reflective layer, the component of the resin layer is interposed through the first reflective layer. Therefore, it is necessary not to be compatible with or react with the organic dye. When the crystal grains of the first reflective layer are large as in the case of a pure metal thin film, the thin film tends to be island-shaped, and resin or the like easily penetrates from the grain boundary, so that the characteristics of the first recording layer are deteriorated.

Examples of the metal or metalloid oxide used in the first reflective layer or auxiliary layer include aluminum oxide, titanium oxide, chromium oxide, magnesium oxide, zirconium oxide, tantalum oxide, silicon oxide, calcium oxide, tin oxide, indium oxide, Examples thereof include indium tin oxide. Similarly, examples of the metal or metalloid nitride include aluminum nitride, titanium nitride, silicon nitride, and zirconium nitride.
A barrier layer may be provided between the second recording layer and the transparent intermediate layer for the purpose of chemically and physically protecting the second recording layer made of a dye. Examples of materials used for the barrier layer _{include SiO, SiO 2, MgF 2,} SnO 2, ZnS, optical transparency, such as ZnS-SiO ₂ is high inorganic material. The film thickness of the barrier layer needs to be in the range of 100 to 2000 mm.
The transparent intermediate layer is preferably used as an adhesive layer, and as the material thereof, an existing acrylate-based, epoxy-based, urethane-based ultraviolet curable adhesive or thermosetting adhesive can be used. Furthermore, the method of bonding with a transparent sheet may be used.
Further, as shown in FIG. 5, a second overcoat layer may be provided between the barrier layer and the transparent intermediate layer with an acrylic, epoxy-based ultraviolet curable resin or the like for chemical and physical protection.

In the case where an alloy containing Au, Ag, or Cu as a main component is used as the material for the semi-transmissive first reflective layer, Au, Ag, Cu, Al, Using a target to which 1 to 10% by weight of at least one selected from Ti, V, Cr, Ni, Nd, Mg, Pd, Zr, Pt, Ta, W, Si, Zn, and In was added, a pressure of 0. An alloy reflective layer can be formed by sputtering at a power of 1 to ²⁰ W / cm ^{2 in} an Ar atmosphere of 01 Pa to several Pa.
Further, as a material of the semi-transmissive first reflective layer, when using a mixture of the above alloy and a metal or metalloid oxide and / or nitride, or a metal or metalloid simple substance, oxide, In the case of using at least two kinds of mixtures selected from nitrides, they can be formed by sputtering using a target in which each material is mixed at a predetermined ratio. Moreover, a mixture thin film can also be formed by simultaneously discharging and sputtering a plurality of targets on which each material of the mixture is set.

When laminating the first reflective layer made of metal or metalloid and the auxiliary layer made of metal or metalloid oxide or nitride, first, Au, Ag, Cu, Al, Ti, Cr, Mg, Ta, A film made of any of W, Si, Zr, etc. is formed by sputtering, followed by aluminum oxide, titanium oxide, chromium oxide, magnesium oxide, zirconium oxide, tantalum oxide, silicon oxide, calcium oxide, tin oxide, indium oxide, etc. A laminated film may be formed by sputtering using a target consisting of at least one of the above, and Al, Ti, Cr, Mg, Zr, Ta, Si, Ca, Oxidized by reactive sputtering using Ar, O ₂ mixed gas, targeting at least one of Sn, In, ITO, etc. A film may be formed.
Similarly, a nitride film can be laminated on the sputtered film made of the above metal or metalloid with at least one of aluminum nitride, titanium nitride, silicon nitride, zirconium nitride and the like as targets, and Al, Ti, A nitride film can also be formed with a mixed gas of Ar and N ₂ with at least one of Si, Zr, etc. as a target.
Further, when an auxiliary layer similar to the above is laminated on the first reflective layer made of an alloy mainly composed of any one of Au, Ag, and Cu, the reflective layer made of the alloy is first formed by sputtering. Subsequently, an auxiliary layer may be laminated in the same manner as described above.

  According to the present invention, a single-sided, double-layer recording / reproducing type in which good recording signal characteristics can be obtained from two information recording layers with high sensitivity, no deterioration under a high temperature and high humidity environment, and high productivity and reliability. An optical recording medium can be provided.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited by these Examples.

更に、第１の記録層の上に、Ａｒをスパッタガスとし、表１に示す第１反射層組成と同じ組成のスパッタリングターゲットを用いて、スパッタ法により実施例１〜３０、比較例１〜７の第１反射層を形成した。スパッタリングはＵｎａｘｉｓ社製スパッタリング装置Ｂｉｇ Ｓｐｒｉｎｔｅｒを用いて、Ａｒ流量２０ｓｃｃｍ、スパッタリングパワー０．５ｋＷで行い、スパッタリングレートは概ね５．５ｎｍ／ｓとした。 <Examples 1-32 and Comparative Examples 1-7>
A first substrate having a guide groove uneven pattern having a depth of about 150 nm, a groove width of about 0.25 μm, and a track pitch of 0.74 μm is prepared on the surface of a polycarbonate substrate having a diameter of 120 mm and a thickness of 0.58 mm. The squarylium dye compound of [Chemical formula 1] and the formazan chelate dye of the following [Chemical formula 2] are mixed at a ratio of 7: 3, dissolved in 2,2,3,3-tetrafluoropropanol, and spin-coated as a coating solution. Thus, the first recording layer was provided. This recording layer had a maximum absorption wavelength of 609 nm and an absorbance (Abs) at the maximum absorption wavelength of 0.65. At this time, the thickness of the recording layer in the groove portion was 60 nm.

Further, Examples 1 to 30 and Comparative Examples 1 to 7 are formed on the first recording layer by sputtering using Ar as a sputtering gas and using a sputtering target having the same composition as the first reflective layer composition shown in Table 1. The first reflective layer was formed. Sputtering was performed using a sputtering apparatus Big Sprinter manufactured by Unaxis, with an Ar flow rate of 20 sccm and a sputtering power of 0.5 kW, and the sputtering rate was approximately 5.5 nm / s.

On the other hand, a second substrate having a guide groove uneven pattern having a depth of about 20 nm, a groove width of about 0.25 μm, and a track pitch of 0.74 μm is prepared on the surface of a polycarbonate substrate having a diameter of 120 mm and a thickness of 0.60 mm. As a sputtering gas, Ag was formed to a thickness of about 120 nm by sputtering to form a second reflective layer. Sputtering was performed using the same apparatus as the first reflective layer at an Ar flow rate of 20 sccm and a sputtering power of 3.5 kW, and the sputtering rate was 30 nm / s.
Further, the second recording layer is formed by spin-coating the squarylium dye compound of [Chemical Formula 1] on the second reflective layer so that the absorbance is 1.6, and Ar is formed thereon. As a sputtering gas, ZnS—SiO ₂ was provided to a thickness of about 100 nm by a sputtering method to form a barrier layer.
Next, the film-formed first substrate and second substrate were bonded with an ultraviolet curable adhesive (KARAYAD DVD003 manufactured by Nippon Kayaku Co., Ltd.) to obtain an optical recording medium having a layer structure shown in FIG.

A DVD (8-16) signal was recorded on these media using a DVD evaluation apparatus (DDU1000 manufactured by Pulstec Corporation, wavelength: 657 nm, NA: 0.65) at a linear velocity of 8.5 m / s. When the reproduction was evaluated at a linear velocity of .49 m / s, the results shown in Table 1 below were obtained. The recording strategy was (n-2) T multi-pulse system, and the multi-pulse width was 10/16.
Table 1 shows the results of measurement and evaluation of data to clock jitter (data to clock jitter) after these optical recording media were stored for 300 hours under high temperature and high humidity (80 ° C., 85% RH) conditions. . The evaluation criteria are ◎: 8% or less, ◯: less than 9%, and x: 9% or more.
In addition, when the waveform after being stored under the same conditions was observed, in Comparative Examples 1, 2, 5, 6, and 7, a partial decrease in reflectance (dropout) was observed, and deterioration of the reflective film was observed. . In Comparative Example 3, the reflectivity was too low to reproduce with a DVD-ROM drive. In Comparative Example 4, since the reflectance was too high, the light reaching the second recording layer was too weak to record on the second recording layer.

<Examples 33 to 59>
On the first recording layer, Ar was used as a sputtering gas, and the first reflective layer and the auxiliary layer were sequentially formed by sputtering using the same sputtering target having the same composition as the first reflective layer and auxiliary layer shown in Table 2 below. Except for this point, the optical recording medium having the layer structure shown in FIG. 3 was obtained in the same manner as in Example 1.
Recording and reproduction evaluation was performed on these media in the same manner as in Example 1. The results are shown in Table 2.
In addition, Table 1 shows the results (◎ ○ ×) of examining the influence of storage under the high temperature and high humidity conditions for these media in the same manner as in Example 1. Furthermore, after the storage, none of the media showed a partial drop in reflectance (dropout), and the storage characteristics were good. All the recording sensitivities were 30 mW or less.

Sectional drawing which shows the structure of DVD which has a two-layer information recording layer. The figure which shows the layer structural example of the optical recording medium of this invention. The figure which shows the other layer structural example (when it has an auxiliary | assistant layer) of the optical recording medium of this invention. The figure which shows the other layer structural example (when further having a 1st overcoat layer) of the optical recording medium of this invention. The figure which shows the other layer structural example (when it has a 1st, 2nd overcoat layer) of the optical recording medium of this invention. The figure which shows the transmittance | permeability simulation result of the optical recording medium of this invention.

Explanation of symbols

1 Substrate 2 Substrate 3 Transflective layer 4 Reflective layer 5 Transparent intermediate layer

Claims (7)

  An optical recording medium capable of recording and / or reproducing optically readable information, comprising at least a first substrate on which a first recording layer made of an organic dye and a semi-transmissive first reflective layer are laminated, and at least A second substrate on which a second recording layer and a second recording layer made of an organic dye are laminated are provided so that both substrates are on the outside through a transparent intermediate layer, and the first reflection layer is Au, One of Ag and Cu as a main component, selected from Au, Ag, Cu, Al, Ti, V, Cr, Ni, Nd, Mg, Pd, Zr, Pt, Ta, W, Si, Zn, In An optical recording medium comprising an alloy containing at least one kind, wherein the light transmittance of the reflective layer is 30 to 60% and the light reflectance is 15 to 35%.   An optical recording medium capable of recording and / or reproducing optically readable information, comprising at least a first substrate on which a first recording layer made of an organic dye and a semi-transmissive first reflective layer are laminated, and at least A second substrate on which a second recording layer and a second recording layer made of an organic dye are laminated are provided so that both substrates are on the outside through a transparent intermediate layer, and the first reflection layer is Au, One of Ag and Cu as a main component, selected from Au, Ag, Cu, Al, Ti, V, Cr, Ni, Nd, Mg, Pd, Zr, Pt, Ta, W, Si, Zn, In It is made of a mixture of an alloy containing at least one kind and a metal or metalloid oxide and / or nitride, and the light transmittance of the reflective layer is 30 to 60% and the light reflectance is 15 to 35%. An optical recording medium comprising:   An optical recording medium capable of recording and / or reproducing optically readable information, comprising at least a first substrate on which a first recording layer made of an organic dye and a semi-transmissive first reflective layer are laminated, and at least The second reflective layer and the second substrate on which the second recording layer made of an organic dye is laminated are provided so that both substrates are outside through the transparent intermediate layer, and the first reflective layer is made of metal or It is composed of at least two kinds of mixtures selected from a single metal, an oxide, and a nitride, and the reflective layer has a light transmittance of 30 to 60% and a light reflectance of 15 to 35%. Optical recording media.   An optical recording medium capable of recording and / or reproducing optically readable information, comprising at least a first substrate on which a first recording layer made of an organic dye and a semi-transmissive first reflective layer are laminated, and at least A second reflective layer and a second substrate on which a second recording layer made of an organic dye is laminated so that both substrates are located outside via a transparent intermediate layer, and the first reflective layer is made of metal or half It is made of a single metal, the light transmittance of the reflective layer is 30 to 60% and the light reflectance is 15 to 35%, and the auxiliary layer is made of an oxide or nitride of a metal or a semimetal. Optical recording media.   An optical recording medium capable of recording and / or reproducing optically readable information, comprising at least a first substrate on which a first recording layer made of an organic dye and a semi-transmissive first reflective layer are laminated, and at least A second substrate on which a second recording layer and a second recording layer made of an organic dye are laminated are provided so that both substrates are on the outside through a transparent intermediate layer, and the first reflection layer is Au, One of Ag and Cu as a main component, selected from Au, Ag, Cu, Al, Ti, V, Cr, Ni, Nd, Mg, Pd, Zr, Pt, Ta, W, Si, Zn, In It is made of an alloy containing at least one kind, the light transmittance of the reflective layer is 30 to 60% and the light reflectance is 15 to 35%, and the auxiliary layer is made of a metal or metalloid oxide or nitride. An optical recording medium characterized by the above.   The metal or metalloid used for the first reflective layer is any one of Au, Ag, Cu, Al, Ti, Cr, Mg, Ta, W, Si, and Zr, and is used for the first reflective layer or the auxiliary layer. The metal or metalloid oxide includes at least one of aluminum oxide, titanium oxide, chromium oxide, magnesium oxide, zirconium oxide, tantalum oxide, silicon oxide, calcium oxide, tin oxide, indium oxide, and indium tin oxide. The optical recording medium according to claim 2, wherein: The metal or metalloid used for the first reflective layer is any one of Au, Ag, Cu, Al, Ti, Cr, Mg, Ta, W, Si, and Zr, and is used for the first reflective layer or the auxiliary layer. 6. The optical recording medium according to claim 2, wherein the metal or metalloid nitride includes at least one of aluminum nitride, titanium nitride, silicon nitride, and zirconium nitride.

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