JP2004087070A - Write-once optical recording media - Google Patents

Abstract

A write-once optical recording medium made of an organic material capable of recording even in a blue laser wavelength region, and capable of increasing the density, having a large degree of modulation, and having a recording characteristic against fluctuations in recording / reproducing wavelength. Write-once optical recording medium with little change in reflectance and reflectivity, and even when a material having no absorption maximum at the laser wavelength used for recording is selected as a recording material, it is possible to perform detailed recording shape control. Of optical recording media.
A postscript wherein a lower heat-receiving layer, a light-absorbing layer made of an inorganic material, and an upper heat-receiving layer are provided in this order on a light-transmitting substrate, and further a reflection layer is provided directly or via an intermediate layer. In the type optical recording medium, the lower heat receiving layer and / or the upper heat receiving layer cause the material to undergo a thermal state change (melting, melting, decomposition, sublimation, etc.) at a lower temperature than the light absorbing layer, and / or A write-once optical recording medium that causes a shape change (expansion, depression, cavitation, irregularity deformation, etc.) due to heat.
[Selection diagram] Fig. 1

Description

【００４９】
＜記録条件＞
記録線速度：６．０（ｍ／ｓ）
記録ストラテジ：Ｂａｓｉｃ　ｓｔｒａｔｅｇｙ（基本ストラテジ）
Ｔｔｏｐ−Ｔｍｐ＝１．４０−０．７５（Ｔ）
記録パワー：１１．０（ｍＷ）
記録パターン：３Ｔ、４Ｔ、５Ｔ、８Ｔ、１４Ｔの単一周期信号
上記の記録条件は記録媒体の記録部を観察しながら決定した。具体的には、熱受容層を境目として媒体を剥離し光学顕微鏡で観察したところ、変質部の色素材料が反射層に優先的に癒着し、非変質部は光吸収層側に優先的に癒着していた。更に、熱受容層を境目として剥離された反射層及び光吸収層にエタノールを滴下して変質の範囲を測定し、その結果を記録条件に反映させることにより、上記の記録条件を見出した。
ランドに記録した場合の記録部の断面の様子を図８に、グルーブに記録した場合の記録部の断面の様子を図９に示す。各図中の１０１（×印の部分）は、下部熱受容層及び上部熱受容層の材料が変質した部分を示しており、これらの図から分るように、本実施例では、熱受容層の記録スポットの中央部の色素量が減少し、溶解特性が変化する変質が見られた。
ここで、用いた記録スポット径ｒとは、ｒ＝λ／ＮＡ×１．２２（エアリー像）で表される範囲である。
この媒体では、光吸収層に１０個以上のφ＝２μｍのポア、４個のφ＝５μｍのポア、１個のφ＝１０μｍのポアが存在し、この影響により、２２５μｍ^２の範囲で、平均膜厚より平均膜厚の２％以上薄い部分があったが、プレーヤーでエラー訂正され良好に再生することができた。
また、ポアが存在しない部分でも島状の平均膜厚より平均膜厚の２％以上薄い部分が確認できた。この部分は連続気泡ではなく独立気泡となっていた。
このように、記録部の形状や記録部の変質の程度を、上記変質の確認方法により確認することにより、未記録部の反射率を１００とした場合の記録部の反射率を１０〜２５０の範囲で任意に調整できる。
【００５０】
実施例２
光吸収層としてＳｉＣをスパッタ法により成膜した点以外は、実施例１と同様にして追記型光記録媒体を作製し、実施例１と同様の記録を行ったところ、明瞭な信号が得られた。
光吸収層を、ＳｉＣに代えて、Ｆｅ、Ｔｉ、Ｚｒ、Ｔａ、Ｃｒ、Ｍｏ、Ｗ、Ｎｉ、Ｒｈ、Ｐｄ、Ｐｔ、Ｃｕ、Ａｇ、Ａｕ、Ｚｎ、Ａｌ、Ｉｎ、Ｇｅ、Ｔｅ、Ｓｎ、Ｂｉ、Ｓｂ、Ｔｌ及びＰｔからなる群より選ばれる少なくとも一種の物質を用いて成膜した場合も同様の効果が得られた。
【００５１】
実施例３
基板上に、ＳｉＣをスパッタ法で成膜し、その上に下記〔化２〕のシアニン色素と〔化３〕のメロシアニン色素の混合物からなる有機材料層をスピンコート法によって形成し、平均膜厚１００ｎｍの二層構造の下部熱受容層を形成した点以外は、実施例１と同様にして追記型光記録媒体を作製し、実施例１と同様の記録を行ったところ、短マーク、長マークとも、変調度が充分大きく非常に明瞭な信号が得られた。
【００５２】
【化２】

【化３】

【００５３】
実施例４
基板上に、ＳｉＣをスパッタ法で成膜し、その上に、下記一般式〔化４〕で示されるフタロシアニン色素の一種であるテトラβ−（１−ベンズイミダゾリル）フタロシアニンと下記一般式〔化５〕で示されるナフタロシアニン色素の一種であるバナジル−５，１４，２３，３２−テトラフェニル−２，３−ナフタロシアニンとの混合物からなる有機材料層をスピンコート法によって形成し、平均膜厚１００ｎｍの二層構造の下部熱受容層を形成した点以外は、実施例１と同様にして追記型光記録媒体を作製し、実施例１と同様の記録を行ったところ、短マーク、長マークとも、変調度が充分大きく非常に明瞭な信号が得られた。
【００５４】
【化４】

【化５】

【００５５】
実施例５
基板上に、ＳｉＣをスパッタ法で成膜し、その上に下記一般式〔化６〕で示されるアゾ染料の一種であるＲ_１〜Ｒ_６＝Ｈの染料からなる有機材料層をスピンコート法によって形成し、平均膜厚１００ｎｍの二層構造の下部熱受容層を形成した点以外は、実施例１と同様にして追記型光記録媒体を作製し、実施例１と同様の記録を行ったところ、短マーク、長マークとも、変調度が充分大きく非常に明瞭な信号が得られた。
【化６】

【００５６】
実施例６〜８
図１、図２に示すプリフォーマットパターンを有するポリカーボネート基板上に、１重量％に調整されたアゾベンゼンのフッ化アルコール溶液をスピンコートし、アゾベンゼンのλｍａｘ＝５９７ｎｍの吸光度が０．２になるように、下部熱受容層（光吸収性を有する）を形成した。このアゾベンゼンの分解温度は３８７度である。
次に、この下部熱受容層上に、スパッタ法で、膜厚５ｎｍ（実施例６）、１０ｎｍ（実施例７）、１５ｎｍ（実施例８）のＳｉＣ膜を形成し光吸収層とした。
次に、各光吸収層上に、１重量％に調整されたアゾベンゼンのフッ化アルコール溶液をスピンコートし、アゾベンゼンのλｍａｘ＝５９７ｎｍの吸光度が０．４になるようにして上部熱受容層を形成した。
次に、各上部熱受容層上に、スパッタ法により膜厚１００ｎｍの銀膜を形成し反射層とした。
次に、各反射層上に、大日本インキ化学工業社製の光硬化性樹脂ＳＤ１７００（熱伝導率１．０以下）を膜厚５μｍで積層し保護層とした。
以上のようにして作製した実施例６〜８の媒体に、波長４０５ｎｍ、膜面パワー１０ｍＷの光を照射し、媒体を６ｍ／ｓで回転させながら記録を行ったところ、光吸収層が光を吸収し、その熱で下部熱受容層、上部熱受容層、反射層が変形し、記録前後に十分な反射率差が得られる良好な記録を行うことができた。
【００５７】
実施例９〜１１
図１、図２に示すプリフォーマットパターンを有するポリカーボネート基板上に、１重量％に調整されたシアニン色素のフッ化アルコール溶液をスピンコートし、シアニン色素のλｍａｘ＝６３２ｎｍの吸光度が０．２になるように、下部熱受容層（光吸収性を有する）を形成した。このシアニン色素の分解温度は１６０度である。
次に、この下部熱受容層上に、スパッタ法で膜厚、５ｎｍ（実施例９）、１０ｎｍ（実施例１０）、１５ｎｍ（実施例１１）のＳｉＣ膜を形成し光吸収層とした。
次に、各光吸収層上に、アゾベンゼンのフッ化アルコール溶液をスピンコートし、アゾベンゼンのλｍａｘ＝５９７ｎｍの吸光度が０．４になるように上部熱受容層を形成した。
次に、各上部熱受容層上に、スパッタ法で膜厚１００ｎｍの銀膜を形成し反射層とした。
次に、各反射層上に、大日本インキ化学工業社製の光硬化性樹脂ＳＤ１７００（熱伝導率１．０以下）を膜厚５μｍで積層し保護層とした。
以上のようにして作製した実施例９〜１１の媒体に、波長４０５ｎｍ、膜面パワー１０ｍＷの光を照射し、媒体を６ｍ／ｓで回転させながら記録を行ったところ、光吸収層が光を吸収し、その熱で下部熱受容層、上部熱受容層、反射層が変形し、記録前後に十分な反射率差が得られる良好な記録を行うことができた。
【００５８】
実施例１２
図１、図２に示すプリフォーマットパターンを有するポリカーボネート基板１上に、銀膜をスパッタ法で成膜して反射層とし、その上に、実施例１と同じ〔化１〕で示される色素からなる有機材料層（上部熱受容層に相当）をスピンコート法によって形成し（平均膜厚１００ｎｍ）、その上に、ＳｉＣ光吸収層を厚さ１２ｎｍで設けた光記録媒体を作成し、その上に、〔化１〕で示される色素からなる有機材料層（下部熱受容層に相当）をスピンコート法によって形成し、更にその上に、０．１ｍｍのポリカーボネート製保護層を積層した。
なお、４０５ｎｍにおける〔化１〕の複素屈折率は、１．４８５−ｉ０．０６９であり、追記型光記録媒体に用いる有機材料に要求される複素屈折率に対し、著しく劣った複素屈折率である（例えばＤＶＤ−Ｒに用いられている色素の、記録再生波長近傍での複素屈折率は、２．５−ｉ０．１０程度である）。
上記光記録媒体に対し、パルステック工業社製の光ディスク評価装置ＤＤＵ−１０００を用いて、以下の条件で記録を行なった結果、短マーク及び長マークとも、変調度が充分大きく非常に明瞭な信号が得られた。
＜記録条件＞
記録線密度：０．０９１７（μｍ／ｂｉｔ）
記録線速度：６．０（ｍ／ｓ）
記録ストラテジ：Ｂａｓｉｃ　ｓｔｒａｔｅｇｙ　Ｔｔｏｐ−Ｔｍｐ＝
１．４０−０．７５（Ｔ）
記録パワー：１１．０（ｍＷ）
記録パターン：３Ｔ、４Ｔ、５Ｔ、８Ｔ、１４Ｔの単一周期信号
【００５９】
【発明の効果】
本発明１〜１５によれば、大容量で波長依存性が少なく、ジッターの少ない良好な記録を行うことができる追記型光記録媒体を提供できる。
更に本発明３によれば、コントラストの大きな信号特性を有する追記型光記録媒体を提供できる。
更に本発明８によれば、記録形状の把握が容易であり、記録条件の算出が簡単な追記型光記録媒体を提供できる。
更に本発明１２によれば、光から熱への変換が良好な追記型光記録媒体を提供できる。
更に本発明１３によれば、記録層の多層化が可能な追記型光記録媒体を提供できる。
本発明１４によれば、記録の際に光吸収層より発する熱で反射層が変形することにより大きなコントラストが得られる追記型光記録媒体を提供できる。
本発明１５によれば、キズや水等から保護された追記型光記録媒体を提供できる。
【図面の簡単な説明】
【図１】本発明の追記型光記録媒体の層構成の一例（第一の例）を示す要部拡大断面図。
【図２】本発明の追記型光記録媒体（光ディスク）の構成の一例を示す斜視図。
【図３】本発明の追記型光記録媒体の記録状態の一例を示す要部拡大断面図。
【図４】本発明の追記型光記録媒体の記録状態の一例を示す要部拡大断面図。
【図５】本発明の追記型光記録媒体の記録状態の一例を示す要部拡大断面図。
【図６】本発明の追記型光記録媒体の記録状態の一例を示す要部拡大断面図。
【図７】本発明の追記型光記録媒体の記録状態の一例を示す要部拡大断面図。
【図８】本発明の追記型光記録媒体の記録状態における熱受容層の変質の様子を示す要部拡大断面図（ランド記録の場合）。
【図９】本発明の追記型光記録媒体の記録状態における熱受容層の変質の様子を示す要部拡大断面図（グルーブ記録の場合）。
【図１０】本発明の追記型光記録媒体の第二の例の要部拡大断面図。
【図１１】本発明の追記型光記録媒体（ディスク）の製造工程の一例のフローチャート。
【符号の説明】
１　透明基板
１ａ　センタ孔
２　プリフォーマットパターン
２ａ　案内溝
２ｂ　プリピット
２ｃ　ランド部
３　下部熱受容層
４　無機材料からなる光吸収層
５　上部熱受容層
６　中間層
１０　反射層
１５　保護層
１０１　色素の変質した部分[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a write-once optical recording medium on which information can be recorded and reproduced by a laser.
[0002]
[Prior art]
The development of a blue laser capable of recording at an ultra-high density is progressing rapidly, and a write-once optical recording medium corresponding to the development is being developed.
In a conventional write-once optical recording medium, a recording pit is formed by irradiating a recording layer made of an organic material with a laser beam and mainly causing a change in the refractive index due to decomposition and deterioration of the organic material. The optical constant and decomposition behavior of the organic material used are important factors for forming a good recording pit.
Therefore, as the organic material used for the recording layer, it is necessary to select an appropriate material having optical properties and decomposition behavior with respect to the blue laser wavelength.
However, no material has been found whose optical properties with respect to the wavelength of the blue laser have a value comparable to that of the conventional art. Because, in order to have the absorption band of the organic material near the blue laser wavelength, it is necessary to reduce the molecular skeleton or shorten the conjugated system, but this causes a decrease in the absorption coefficient, that is, a decrease in the refractive index. That's why.
That is, there are many organic materials having an absorption band near the wavelength of the blue laser, and although the absorption coefficient can be controlled, a large degree of modulation cannot be obtained because the organic material does not have a large refractive index.
[0003]
Patent Documents 1 to 5 disclose, for example, organic materials compatible with a blue laser. However, in these publications, only the spectra of the solution and the thin film are measured in the examples, and there is no description about recording / reproducing.
In Patent Documents 6 to 8, although recording is described in Examples, the recording wavelength is 488 nm, and there is no description on recording conditions or recording density, only that a good recording pit was formed. It is.
In Patent Document 9, although recording is described in Examples, the recording wavelength is 430 nm, and there is no description about recording conditions or recording density, but only a statement that a good degree of modulation was obtained. .
[0004]
Patent Documents 10 to 19 include examples in which recording is performed at a recording wavelength of 430 nm and an NA of 0.65 in Examples, but the recording density is as low as 0.4 μm (the recording density is equivalent to that of DVD).
Patent Document 20 describes a recording / reproducing wavelength of 405 to 408 nm, but does not specifically describe a recording density, and is a low recording density condition of recording a 14T-EFM signal.
[0005]
Further, regarding the layer configuration and recording method different from the conventional CD and DVD optical recording media, the following technologies are disclosed.
Patent Document 21 discloses a technique of performing recording by changing the extinction coefficient (absorption coefficient in the present invention) of a saturable absorbing dye in a configuration of a substrate / a saturable absorbing dye-containing layer / a reflective layer.
Patent Document 22 discloses a technique in which recording is performed by discoloring or deforming a metal vapor deposited layer by heat generated by the light absorbing layer in a configuration of a substrate / metal vapor deposited layer / light absorbing layer / protective sheet. .
Patent Document 23 discloses a technique of performing recording by changing the film thickness of a recording layer and changing the depth of a groove in a configuration of a substrate / dielectric layer / recording layer including a light absorber / reflection layer. .
Patent Document 24 discloses a technique of performing recording by changing the thickness of a recording layer by 10 to 30% in a configuration of a substrate / a recording layer including a light absorber / a metal reflection layer.
[0006]
Patent Document 25 discloses a technique of performing recording by increasing the groove width of a substrate by 20 to 40% with respect to an unrecorded portion in a configuration of a substrate / a recording layer containing an organic dye / a metal reflective layer / a protective layer. It has been disclosed.
Patent Document 26 discloses a technique of performing recording by forming a bubble by deforming a metal thin film in a configuration of a substrate / intermediate layer / metal thin film.
Patent Literature 27 discloses a technique in which heat is released to an insulating film to correct a recording portion by using a structure of a substrate / insulating layer / cyanine recording film / reflective film / protective film.
Patent Document 28 discloses that a recording auxiliary layer is deformed into a concave shape, and a light reflecting layer is deformed into a concave shape along with the deformation of the recording auxiliary layer in a configuration of a substrate / a light absorbing layer / a recording auxiliary layer / a light reflecting layer. Discloses a technique for performing recording.
[0007]
Patent Document 29 discloses that a recording auxiliary layer is formed in a concave shape with a configuration of a substrate / a light absorbing layer / a porous recording auxiliary layer / a light reflecting layer or a substrate / a porous recording auxiliary layer / a light absorbing layer / a light reflecting layer. There is disclosed a technique of performing recording by deforming the light reflection layer in a concave shape along with the deformation of the recording auxiliary layer.
Patent Document 30 discloses a configuration in which a substrate / porous light absorbing layer / light reflecting layer has a configuration in which the light absorbing layer is deformed concavely and the light reflecting layer is deformed concavely along the deformation of the light absorbing layer. Is disclosed.
Patent Literature 31 discloses a configuration of a substrate / a recording layer containing an organic dye / a recording auxiliary layer, in which the recording auxiliary layer and the organic dye are compatible with each other and the absorption spectrum of the organic dye is shifted to a shorter wavelength side to perform recording. Performing techniques are disclosed.
However, none of the above techniques aims at realizing an optical recording medium in the blue laser wavelength range, and is not a layer configuration or a recording method effective in the blue laser wavelength range.
[0008]
As described above, at the present stage, the recording layer of the conventional write-once type optical recording medium is required in the blue laser wavelength region, particularly in the vicinity of 405 nm, which is the center of the oscillation wavelength of the blue semiconductor laser currently in practical use. Almost no organic material has an optical constant similar to the optical constant. Further, there is no example in which recording conditions are clarified in the vicinity of 405 nm and recording is performed at a higher recording density than that of DVD.
Further, the examples in the above publications are experiments with a conventional disk configuration, and effective for a layer configuration, a recording principle, and a recording method for easily realizing a write-once optical recording medium made of an organic material in a blue laser wavelength region. No suggestion.
Conventionally, in a write-once optical recording medium made of an organic material, the wavelength dependence of the optical constant of the organic material is large (the optical constant greatly fluctuates depending on the wavelength). However, there is a problem that recording characteristics such as recording sensitivity, modulation degree, jitter, and error rate, reflectance, and the like greatly change with respect to fluctuation of the recording / reproducing wavelength due to the above.
[0009]
On the other hand, as a conventional technique, Patent Documents 32 to 37 disclose, in an optical recording medium having a substrate on which a pre-groove is formed and a metal recording film, a buffer layer, and a reflective layer sequentially laminated on the substrate, the buffer. The layer is a substance having a low absorbance to a laser beam having a wavelength of 600 to 800 nm, from an organic substance having an absorbance (k) of 1.0 or less at 650 nm and 0.1 or less at 780 nm. An optical recording medium has been proposed.
In Patent Document 38, as a technique relating to an underlayer, an increasing / decreasing layer made of gelatin, casein, polyvinyl alcohol (PVA) and the like and a metal thin film recording layer made of Cr, Ni, Au and the like are laminated in this order on a substrate. A recording medium is disclosed. According to the optical recording principle of the recording medium, the metal thin film absorbs the heat of the irradiated laser beam, and the heat deforms the increase / decrease layer and the metal thin film to form recording pits. However, since the recording pits of the recording medium are exposed, it is difficult to store the recorded information for a long time.
[0010]
Further, Patent Document 39 discloses a transparent substrate on which a preformat pattern having at least a light beam guide portion is formed, and a light-reflecting material attached to a preformat pattern forming surface of the transparent substrate via an organic dye layer. Film, a recording film made of a heat mode recording material or a photon mode recording material laminated directly or via another thin film on the light reflective film, and a protective film covering the outside of the recording film. A write-once optical recording medium characterized as a feature has been proposed.
Further, in Patent Document 40, the disk substrate is formed of polymethyl methacrylate, polycarbonate, or epoxy resin, the recording layer is formed of an alloy mainly containing tellurium, and the underlayer is methane, propane, ethylene, propylene, At least one selected from acetylene, benzene, styrene, tetramethylsilane, hexamethyldisilane, hexamethyldisilazane, hexamethylsiloxane, octamethylcyclotetrasiloxane, tetramethyltin, tetramethylgermanium, ferrocene, and pentaethoxytantalum An optical information recording disc characterized by being formed from an organic substance has been proposed.
[0011]
In the above prior art, the underlying layer is provided with an auxiliary role in order to increase the efficiency in forming pits or the like on the recording layer. However, when the recording layer has a high refractive index and a high absorptance, the function of the underlayer may be auxiliary, but in the case of a dye material, suitable optical characteristics are obtained in the irradiation laser wavelength range of 350 to 450 nm. At present, there are few organic recording materials.
On the other hand, recording can be performed by providing a layer (heat receiving layer) that has no absorption at the irradiation laser wavelength but can receive heat, and each layer changes optically by the heat. It is possible.
For example, when light is absorbed and converted into heat by the light absorbing layer and the heat is transferred to the heat receiving layer for recording, the heat from the light absorbing layer is transferred to the upper and lower layers. However, especially when the light absorbing layer is formed directly on the substrate, the thermal behavior centered on the specific heat of the light absorbing layer is directly transmitted to the substrate, and the thermal characteristics of the substrate become dominant, and the dense recording shape Control becomes impossible.
[0012]
[Patent Document 1]
JP 2001-181524 A
[Patent Document 2]
JP 2001-158865 A
[Patent Document 3]
JP 2000-343824 A
[Patent Document 4]
JP 2000-343825 A
[Patent Document 5]
JP 2000-335110 A
[Patent Document 6]
JP-A-11-221964
[Patent Document 7]
JP-A-11-334206
[Patent Document 8]
JP 2000-43423 A
[Patent Document 9]
JP-A-11-58955
[Patent Document 10]
JP 2001-39034 A
[Patent Document 11]
JP-A-2000-149320
[Patent Document 12]
JP 2000-113504 A
[Patent Document 13]
JP 2000-108513 A
[Patent Document 14]
JP 2000-222772 A
[Patent Document 15]
JP 2000-218940 A
[Patent Document 16]
JP-A-2000-222771
[Patent Document 17]
JP 2000-158818 A
[Patent Document 18]
JP 2000-280621 A
[Patent Document 19]
JP 2000-280620 A
[Patent Document 20]
JP 2001-146074 A
[Patent Document 21]
JP-A-7-304258
[Patent Document 22]
JP-A-8-83439
[Patent Document 23]
JP-A-8-138245
[Patent Document 24]
JP-A-8-2977838
[Patent Document 25]
JP-A-9-198714
[Patent Document 26]
Japanese Patent No. 2506374
[Patent Document 27]
Japanese Patent No. 250667
[Patent Document 28]
Japanese Patent No. 2591939
[Patent Document 29]
Japanese Patent No. 2591940
[Patent Document 30]
Japanese Patent No. 2591941
[Patent Document 31]
Japanese Patent No. 2982925
[Patent Document 32]
Japanese Patent No. 2966377
[Patent Document 33]
JP-A-10-134415
[Patent Document 34]
JP-A-10-124926
[Patent Document 35]
JP-A-10-124927
[Patent Document 36]
JP-A-9-265660
[Patent Document 37]
JP 2000-516007 A
[Patent Document 38]
JP-A-63-268142
[Patent Document 39]
Japanese Patent No. 3222434
[Patent Document 40]
Japanese Patent Publication No. 08-003914
[0013]
[Problems to be solved by the invention]
In view of the above prior art, the present invention is a write-once optical recording medium made of an organic material, which can record even in a blue laser wavelength region, particularly in a wavelength region near 405 nm, and is capable of high density. A write-once optical recording medium with a large degree of modulation and a small change in recording characteristics such as recording sensitivity, degree of modulation, jitter, and error rate with respect to fluctuations in the recording / reproducing wavelength, and a small change in reflectance. It is an object of the present invention to provide a write-once optical recording medium capable of performing detailed control of a recording shape even when a material having no absorption maximum in wavelength is selected as a recording material.
[0014]
[Means for Solving the Problems]
The above object is achieved by the following inventions 1) to 15) (hereinafter referred to as inventions 1 to 15).
1) A write-once type light in which a lower heat-receiving layer, a light-absorbing layer made of an inorganic material, and an upper heat-receiving layer are provided in this order on a light-transmitting substrate, and further a reflection layer is provided directly or via an intermediate layer. In the recording medium, the lower heat receiving layer and / or the upper heat receiving layer may cause the material to undergo a thermal state change (melting, melting, decomposition, sublimation, etc.) at a lower temperature than the light absorbing layer and / or A write-once optical recording medium characterized by causing a shape change (expansion, depression, cavitation, irregularity deformation, etc.).
2) An additional record in which an upper heat-receiving layer, a light-absorbing layer made of an inorganic material, a lower heat-receiving layer, a protective layer or a cover layer is provided in this order on a translucent substrate via a reflective layer, directly or via an intermediate layer. In the type optical recording medium, the lower heat receiving layer and / or the upper heat receiving layer cause the material to undergo a thermal state change (melting, melting, decomposition, sublimation, etc.) at a lower temperature than the light absorbing layer, and / or A write-once optical recording medium characterized by causing a shape change (expansion, depression, cavitation, irregularity deformation, etc.) due to heat.
3) At least one of the lower heat-receiving layer, the light-absorbing layer made of an inorganic material, and the upper heat-receiving layer undergoes a shape change (expansion, depression, cavitation, irregularity, etc.) due to heat when irradiated with a light beam. The write-once optical recording medium according to 1) or 2), wherein recording is performed.
4) The shape change is accompanied by a change in the film thickness of the lower heat-receiving layer and / or the upper heat-receiving layer, and the film thickness of at least a part of the information-recorded part is smaller than the film thickness of the unrecorded part. 3. The write-once optical recording medium according to 3), wherein
5) When recording by irradiating light exhibiting a Gaussian distribution, the amount of the heat receiving layer material in the portion corresponding to the central portion of the Gaussian distribution is larger than the amount of the heat receiving layer material in the portion corresponding to the outer peripheral portion of the Gaussian distribution. Wherein the thickness of the lower heat receiving layer and / or the upper heat receiving layer changes.
6) When recording is performed by irradiating a laser beam, a cavity is formed at the interface between the lower heat receiving layer and / or the upper heat receiving layer and the light absorbing layer made of an inorganic material. The write-once optical recording medium according to any one of the above items.
7) The lower heat receiving layer and / or the upper heat receiving layer is characterized in that recording is performed by causing a change in the melting property of the material in the recording mark area due to a change in the thermal state of the material. The write-once optical recording medium according to any one of 1) to 6).
8) The write-once optical recording medium according to 7), wherein the alteration in which the dissolution characteristic of the material changes is an alteration in a direction in which the solubility of the altered portion decreases and the material becomes harder to melt.
9) The lower heat receiving layer and / or the upper heat receiving layer is made of a material containing an organic substance having a decomposition temperature of 160 to 400 ° C., and the organic substance is an aromatic compound, an aliphatic compound, an amide, an ester, an amine. , Urea, at least one selected from the group consisting of a sulfur compound and a hydroxy compound, or anthraquinone type, dioxidine type, triphenodithiazine type, phenanthrene type, cyanine type, phthalocyanine type, naphthalocyanine type, At least one selected from the group consisting of merocyanine, pyrylium, xanthene, triphenylmethane, croconium, azo, indigoid, methine, azulene, squarylium, sulfide and methanedithiolate dyes And irradiation light of a wavelength used for recording and reproduction. The write-once optical recording medium according to any one of 1) to 8), having an absorbance of 0.4 or less with respect to the optical recording medium.
10) The lower heat-receiving layer and / or the upper heat-receiving layer is an anthraquinone-based, dioxidine-based, triphenodithiazine-based, phenanthrene-based, cyanine-based, phthalocyanine-based, naphthalocyanine-based, merocyanine-based, pyrylium-based, xanthene-based, In addition to at least one dye selected from the group consisting of triphenylmethane-based, croconium-based, azo-based, indigoid-based, methine-based, azulene-based, squarylium-based, sulfide-based, and methanedithiolate-based dyes, a vinyl alcohol-based dye At least one polymer selected from the group consisting of resin, vinyl acetate resin, acrylate resin, polyester resin, polyether resin, polystyrene resin, polyurethane resin, cellulose resin and fatty acid resin. weight %. The write-once optical recording medium according to any one of 1) to 8), wherein the medium is composed of a material containing not more than 1%.
11) The write-once optical recording medium according to any one of 1) to 10), wherein the thickness of the lower heat receiving layer is 5 to 1000 nm, and the thickness of the upper heat receiving layer is 5 to 200 nm. .
12) The light absorbing layer made of an inorganic material is made of Fe, Ti, Zr, Ta, Cr, Mo, W, Ni, Rh, Pd, Pt, Cu, Ag, Au, Zn, Al, In, Si, Ge, Te. , Sn, Bi, Sb, and Tl, the write-once optical recording medium according to any one of 1) to 11), wherein the thickness is 5 to 200 nm. .
13) The write-once optical recording medium according to any one of 1) to 12), wherein the reflective layer does not change its shape (expansion, formation of irregularities, etc.).
14) The information is recorded by changing the shape (expansion, formation of irregularities, etc.) of the reflective layer by heat generated from the light absorbing layer made of an inorganic material when the information is recorded by irradiation with light. 13. The write-once optical recording medium according to any one of claims 12) to 12).
15) The write-once optical recording medium according to any one of 1) to 14), further comprising a protective layer on the reflective layer.
[0015]
Hereinafter, the present invention will be described in detail.
The present inventors have attempted to increase the density even in a blue laser wavelength region where it is difficult to obtain an optical constant similar to the optical constant required for the recording layer of a conventional write-once optical recording medium, and to achieve high density. As a result of studying the recording shape and the recording principle of a write-once optical recording medium capable of obtaining a degree of modulation, the modulation by the refractive index (real part of the complex refractive index), which is conventionally a heat generating layer and is caused by decomposition and alteration, was obtained. By separating the function as a heat generating layer and the function as a modulation degree generating layer from a recording layer made of an organic material that had functioned as a degree generating layer, the intended write-once optical recording medium was successfully obtained.
That is, in the write-once optical recording medium of the present invention, the heat receiving layer changes its thermal state (melting, melting, decomposing) at a temperature lower than that of a light absorbing layer made of an inorganic material (hereinafter referred to as a light absorbing layer). , Sublimation, etc.) and / or recording that causes a shape change (expansion, depression, cavitation, irregularity deformation, etc.) due to heat. More preferably, recording is performed to give the heat-receiving layer an alteration in which the melting property changes, and the medium is irradiated with light exhibiting a Gaussian distribution to record the dye, whereby the dye corresponding to the central portion of the Gaussian distribution is recorded. The degree of modulation is generated by a shape change in which the amount of the layer material is smaller than the amount of the dye layer material in a portion corresponding to the outer peripheral portion of the Gaussian distribution.
As a result, the refractive index of the organic material layer is completely eliminated, and the organic material layer does not need to have a light absorbing ability at the recording / reproducing wavelength.
[0016]
An example (first example) of the configuration of the write-once optical recording medium of the present invention will be described with reference to FIGS. FIG. 1 is an enlarged sectional view of a main part showing an example of a layer configuration of a write-once optical recording medium of the present invention, and FIG. 2 is a perspective view showing an example of a configuration of a write-once optical recording medium (optical disc) of the present invention. .
As is clear from these figures, this write-once optical recording medium has a transparent substrate 1 having a fine irregular preformat pattern 2 on one side, a lower heat receiving layer 3, and a light absorbing layer 4 (hereinafter referred to as an inorganic material). , A light absorbing layer 4), an upper heat receiving layer 5, a reflective layer 10, and a protective layer 15 are laminated in this order.
[0017]
As the transparent substrate 1, for example, a transparent resin material (preferably having a glass transition temperature Tg of 100 to 200 ° C.) such as polycarbonate, polymethyl methacrylate, polymethyl pentene, epoxy resin, polyester, or amorphous polyolefin is formed into a desired shape. Then, a desired preformat pattern is transferred to one side thereof, or a transparent resin layer in which a desired preformat pattern is transferred to one side of a transparent ceramic plate such as glass formed in a desired shape is closely attached. Any known transparent substrate can be used. As shown in FIG. 2, a transparent substrate 1 constituting a disk-shaped write-once optical recording medium (hereinafter, referred to as an optical disk) is formed in a disk shape having a center hole 1a in the center. Note that the transparent substrate 1 can be manufactured by a known method.
Further, the depth of the pregroove formed on the substrate surface is desirably 10 to 200 nm. When the depth is less than 10 nm, the reflectivity greatly increases due to the expansion of the substrate after recording, and the recording signal has more noise. When the depth is more than 200 nm, a deep pre-groove also occurs in the upper heat receiving layer. Therefore, it is difficult to obtain a uniform film.
[0018]
The preformat pattern 2 includes at least a beam guide for causing a recording / reproducing laser beam to follow a recording track.
In the example of FIGS. 1 and 2, the beam guide portion is configured to have a spirally or concentrically formed guide groove 2 a concentric with the center hole 1 a, and along the guide groove 2 a, an address pit or a clock is formed. Pre-pits 2b such as pits are formed.
When the pre-pit 2b is formed on the guide groove 2a so as to be optically distinguishable from each other, the guide groove 2a and the pre-pit 2b are formed at different depths as shown in FIG. Is done. When the pre-pits 2b are formed between adjacent guide grooves 2a, they can be formed at the same depth.
In addition, instead of the guide groove 2a, a wobble pit can be formed along the recording track as the beam guide. Alternatively, the pre-pits 2b may be omitted, and may be formed only by the guide grooves.
[0019]
As a material of the lower heat receiving layer 3, a thermal state change (melting, melting, decomposition, sublimation, etc.) is caused at a temperature lower than that of the light absorbing layer 4 and / or a layer shape change (expansion, depression, A material that causes cavitation, uneven deformation, etc.) is used.
Preferred examples of such a material include a dye.
Examples of dyes include polymethine dyes, anthraquinone dyes, dioxidin dyes, triphenodithiazine dyes, phenanthrene dyes, cyanine dyes, dicarbocyanine dyes, phthalocyanine dyes, naphthalocyanine dyes, and merocyanine Dyes, pyrylium dyes, porphyrin dyes, xanthene dyes, triphenylmethane dyes, azulene dyes, metal-containing azo dyes, azo dyes, azo dyes, squarylium dyes, polyene dyes, base styryl dyes, Formazan chelate dyes, croconium dyes, indigoid dyes, methine dyes, sulfide dyes, methanedithiolate dyes, and the like, among which cyanine derivatives, dicarbocyanine derivatives, phthalocyanine derivatives, and naphthalocyanines Emissions derivatives, azo dye derivatives are particularly preferably used. Alternatively, a dye material to which various quencher such as an aminium dye is added can be used.
[0020]
Further, one or two or more dye materials selected from the above-described dye material group may be dispersed in a resin and used.
Acrylic resin, especially acrylate resin, vinyl resin, especially vinyl alcohol resin, vinyl acetate resin, phenol resin, fluorine resin, silicone resin, polyamide resin, polyester resin, polyether resin , A polystyrene resin, a polyurethane resin, a cellulose resin, a fatty acid-based resin, and the like. In order to sufficiently exhibit the function of the coloring material, the amount of the resin is preferably set to 50% by weight or less of the whole.
[0021]
The lower heat receiving layer 3 is formed by spin-coating, for example, a solvent solution of a dye material selected from the dye material group on the preformat pattern forming surface of the transparent substrate 1. That is, after filling the groove-shaped preformat pattern 2 with the dye material, the dye material adhered to the land portions 2c between the preformat patterns 2 is selectively removed, exposing the surface of the transparent substrate 1 and It is formed by filling the dye material only in the preformat pattern 2. In addition, as a solvent of the coloring material, an alcohol solvent, a cellosolve solvent, or the like can be used.
Further, the dye can be prevented from fading by containing a chelating material capable of taking bidentate coordination. Such chelating materials include inorganic acids, dicarboxylic acids, oxycarboxylic acids, dioxy compounds, oxioximes, oxyaldehydes and derivatives, diketones and similar compounds, oxyquinones, troborones, N-oxide compounds, Aminocarboxylic acids and similar compounds, hydroxylamines, oxines, aldimines, oxyazo compounds, nitrosonaphthols, triazenes, piuretes, formazans and dithizones, biqualides, glyoximes, diamines and similar compounds, Hydrazine derivatives, thioethers and the like can be mentioned.
Furthermore, derivatives having an imino group can also be used.
[0022]
In addition to the above organic materials, a phase change material capable of recording information by changing the atomic arrangement can also be used. Specifically, alloys represented by α-β-γ-Ge-Te can be mentioned.
Here, α is Cu, Ag, Au, Sc, Y, Ti, Zr, V, Nb, Cr, Mo, Mn, Fe, Ru, Co, Rh, Ni, Pd, Hf, Ta, W, Ir, Pt. , Hg, B, C, N, P, O, S, Se, lanthanide element, actinide element, alkaline earth metal element, inert gas element and the like. β represents at least one of a halogen element such as I, an alkali metal element such as Na, and Tl.
γ represents at least one of Sb, Sn, As, Pb, Bi, Zn, Cd, Si, Al, Ga and In.
[0023]
Metal materials used for magneto-optical materials, for example, Tb, Fe, Co, etc .; Fe, Ti, Zr, Ta, Cr, Mo, W, Ni, Rh, Pd, Pt, Cu, Ag, Au, Zn, At least one substance selected from the group consisting of Al, In, Si, Ge, Te, Sn, Bi, Sb, Tl, and Pt; SiO, SiN, AlN, SiC, ZnO ₂ Also, inorganic materials such as silver can be used, and silver or an alloy mainly containing silver is particularly preferable. Here, “mainly composed of silver” means that the silver content is 80 atomic% or more, preferably 90 atomic% or more.
Furthermore, at least one selected from the group consisting of aromatic compounds, aliphatic compounds, amides, esters, amines, ureas, sulfur compounds, and hydroxy compounds can also be used.
The thickness of the lower heat receiving layer 3 is preferably 5 to 1000 nm. If the thickness is less than 5 nm, a defect occurs and a film cannot be formed. On the other hand, if the thickness is more than 1000 nm, the volume is too large and the deformation becomes insufficient.
For example, when SiC is selected as the material, the film thickness is preferably 8 to 14 nm, and when silver is selected, the film thickness is preferably 10 to 40 nm.
Further, the lower heat receiving layer 3 may be a single layer or a multilayer (two or more layers).
[0024]
Examples of the binder when a binder is used in forming the lower heat receiving layer 3 include natural organic high molecular substances such as gelatin, cellulose derivatives, dextran, rosin, and rubber; and polyethylene, polypropylene, polystyrene, and poly. Hydrocarbon resins such as isobutylene; vinyl resins such as polyvinyl chloride, polyvinylidene chloride, and polyvinyl chloride / polyvinyl acetate copolymer; acrylic resins such as polymethyl acrylate and polymethyl methacrylate; polyvinyl alcohol and chlorine Synthetic organic polymers such as polyethylene oxide, epoxy resin, butyral resin, rubber derivative, and initial condensate of thermosetting resin such as phenol / formaldehyde resin.
The amount of the binder used is usually in the range of 0.01 to 50 times (mass ratio), preferably in the range of 0.1 to 5 times (mass ratio) based on the dye. The concentration of the coating solution thus prepared is generally in the range of 0.01 to 10% by mass, preferably in the range of 0.1 to 5% by mass.
Examples of the application method include a spray method, a spin coating method, a dip method, a roll coating method, a blade coating method, a doctor roll method, and a screen printing method.
[0025]
The material of the lower heat receiving layer 3 contains an organic substance having a decomposition temperature of 160 to 400 ° C., and has an absorbance of 0.4 or less after film formation with respect to irradiation light having a wavelength of 350 to 450 nm. Heat is received from the light absorbing layer by the information recording, and a thermal state change (melting, melting, decomposition, sublimation, etc.) is caused at a lower temperature than the light absorbing layer, and / or a shape change (expansion, Those which can cause depression, cavitation, irregularity deformation, etc.) are preferable. If the decomposition temperature is lower than 160 ° C., the deformation becomes large and crosstalk occurs. If the decomposition temperature is higher than 400 ° C., sufficient deformation does not occur, resulting in insufficient recording. In order to allow sufficient light to reach the light absorbing layer, the absorbance is preferably set to 0.4 or less.
[0026]
The lower heat receiving layer 3 is made of a hydrophilic resin such as polyvinyl alcohol, polyethylene oxide, polyacrylic acid, sodium polystyrene sulfonate, polyvinyl pyrrolidone, polymethacrylic acid, polypropylene glycol, methyl cellulose, polyvinyl nitrate, and nitrocellulose. It may be formed.
As a forming method, for example, an aqueous solution of the hydrophilic resin may be spin-coated on the preformat pattern forming surface 2 of the transparent substrate 1 to form a film.
However, since it is made of a hydrophilic resin, it has poor water resistance (moisture resistance and moisture permeability) and heat resistance. Therefore, it is preferable to improve the water resistance and heat resistance by performing a crosslinking treatment or a crystallization treatment. Specifically, a crosslinking agent is added to the aqueous solution of the hydrophilic resin, and after the lower heat receiving layer 3 is formed, a crosslinking reaction by light irradiation or a crosslinking reaction by heating is caused, or no crosslinking agent is added. The lower heat receiving layer 3 is crystallized by heat treatment. For example, when polyvinyl alcohol (PVA) is used as the hydrophilic resin, the PVA is modified into PVA.
[0027]
Comparing the cross-linking treatment with the crystallization treatment, the cross-linking treatment is more preferable since the transparent substrate 1 is not adversely affected by heating and excellent in workability. Specific examples of the cross-linking reaction are shown below, but in practice, any means can be selected and adopted from these cross-linking reactions as needed.
(1) A method in which ammonium dichromate is added as a cross-linking agent, the surface of the dye is treated, and at the same time, a reaction light is irradiated after film formation to cause a cross-linking reaction in the lower heat-receiving layer 3.
(2) A method of adding, for example, copper, boron, aluminum, titanium, zirconium, tin, vanadium, chromium, etc. as an inorganic crosslinking agent.
(3) A method of acetalization using an aldehyde.
(4) A method of converting a hydroxyl group into an aldehyde.
(5) A method of adding an activated vinyl compound.
(6) A method of adding an epoxy compound to form an ether.
(7) A method of causing a dicarboxylic acid reaction under an acid catalyst.
(8) A method of adding succinic acid and sulfuric acid.
(9) A method of adding triethylene glycol and methyl acrylate.
(10) A method of blending a polyacrylic acid and a methylvinylethermaleic acid copolymer.
[0028]
The material, required physical properties and forming method of the upper heat receiving layer 5 are the same as those of the lower heat receiving layer 3 described above. However, since micropores may be present in the light absorbing layer 4, in such a case, it is necessary to form the upper heat receiving layer 5 using a solution having a certain contact angle that does not enter the micropores.
Here, for a certain contact angle that does not enter the micropore, the required surface tension varies depending on the size of the micropore, and thus the value cannot be indicated by a numerical value. However, the area of a portion that is 2% or more of the average film thickness smaller than the average film thickness generated in the micropore portion after film formation is 225 μm. ² Is the upper limit and 225 μm ² Exceeding the range will cause problems such as tracking accuracy and error correction, so even if the solution penetrates into the micropore, if the penetration does not spread beyond the above range, a certain contact angle that will not enter the micropore Is determined to correspond to a solution having
[0029]
Examples of the solvent capable of forming a solution having a certain contact angle that does not enter the micropore include esters such as butyl acetate and cellosolve acetate; ketones such as methyl ethyl ketone, cyclohexanone and methyl isobutyl ketone; dichloromethane; Chlorinated hydrocarbons such as dichloroethane and chloroform; amides such as dimethylformamide; hydrocarbons such as cyclohexane; ethers such as tetrahydrofuran, ethyl ether and dioxane; ethanol, n-propanol, isopropanol, n-butanol, diacetone alcohol and the like. Alcohols; Fluorinated solvents such as 2,2,3,3-tetrafluoropropanol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene Such as glycol ethers such as glycol monomethyl ether.
[0030]
In addition, as these solvents, it is necessary to use those having a solubility of 5 mg / 1 ml or more of the dye used. Therefore, the dyes are used singly or in combination of two or more in consideration of the solubility of the dye used. In addition, various additives such as an antioxidant, a UV absorber, a plasticizer, and a lubricant may be added to the coating solution as needed.
Furthermore, in order to more effectively prevent the penetration into the micropores, after the solution for the lower heat receiving layer is applied, the solution is dried or subjected to a crosslinking treatment, a crystallization treatment, or the like, so that the membrane is fixed at an early stage. Is preferred. As a specific means of the crosslinking treatment, the same means as in the case of using a hydrophilic resin described later can be adopted.
Also, the upper heat receiving layer 5 may be a single layer or a multilayer (two or more layers), like the lower heat receiving layer 3.
The thickness of the upper heat receiving layer 5 is preferably 5 to 200 nm. If the thickness is less than 5 nm, heat absorption is insufficient, and deformation and change become insufficient. On the other hand, if the thickness is more than 200 nm, the volume is too large, so that there is a problem that deformation is suppressed or a portion that cannot be changed optically due to thermal influence is generated.
[0031]
The light absorbing layer 4 is a material that absorbs light energy and converts it into heat energy, and changes the shape of the layer (expansion, depression, unevenness, etc.) at a higher temperature than the lower and upper heat receiving layers 3 and 5. Is used.
Specific examples include Fe, Ti, Zr, Ta, Cr, Mo, W, Ni, Rh, Pd, Pt, Cu, Ag, Au, Zn, Al, In, Si, Ge, Te, Sn, Bi, and Sb. And at least one selected from the group consisting of Tl.
The thermal conductivity of the light absorbing layer 4 is desirably 10 (W / cm · ° C.) or less. When the temperature exceeds 10 (W / cm · ° C.), the heat generated from the light absorbing layer 4 by the laser is rapidly conducted (dissipated) to the surroundings, so that the thin film itself is hardly heated to a required predetermined temperature or more, and the temperature becomes higher than the predetermined temperature. Even if heated, the recording pits are large and may deform adjacent tracks.
Further, the coefficient of linear expansion of the light absorbing layer 4 is 3 × 10 ^-7 / ° C or higher. If the coefficient of linear expansion is smaller than this, cracks occur in the light absorbing layer 4 due to expansion of the substrate during recording, and a uniform recording signal cannot be obtained.
The thickness of the light absorbing layer 4 is preferably 5 to 200 nm. If the film thickness is less than 5 nm, the absorptance decreases and the conversion from light to heat becomes insufficient. On the other hand, when the film thickness is larger than 200 nm, the volume is too large, and the shape change and the heat transmission are insufficient.
As a specific example, the film thickness when SiC is selected is preferably 8 to 14 nm, and the film thickness when silver is selected is preferably 10 to 40 nm.
The light absorption layer 4 may be a single layer or a multilayer (two or more layers).
[0032]
On the other hand, a super-resolution technique can be added to the light absorbing layer 4. Usually, the reproduction limit of an optical disc is represented by λ / 2NA. (Where λ is the wavelength and NA is the sine of the aperture angle of the light)
In order to realize a resolution exceeding this limit, the following super-resolution technology is applied. That is, the intensity distribution I of the reproduction beam obtained by condensing the laser light on the medium by the objective lens is
I = I ₀ × exp [-2 (r / r ₀ ) ² ]
(Where I ₀ Is the intensity at the center of the laser beam, r ₀ Means that the laser beam intensity is 1 / e ² Radius).
When the recording medium is heated by the reproducing beam having the intensity distribution of Gaussian distribution, the temperature distribution of the portion irradiated with the beam also becomes similar to the Gaussian distribution.
By setting a high temperature part near the center of the beam as a reproduction area and a low temperature part around the center as a part not involved in recording / reproduction, the diameter of the effective beam spot is reduced and the resolution is improved.
In the Gaussian distribution, the temperature is about 0.6 times the center temperature, that is, the radius r ₀ The slope becomes steep at / 2. When this portion is matched, stable recording / reproduction becomes possible.
[0033]
The material used for the reflective layer 10 is not particularly limited, but a metal material such as aluminum, silver, and copper, or an alloy material containing these as a main component can be used. In particular, it is preferable to use silver or an alloy containing silver as a main component. Here, “mainly composed of silver” means that the silver content is 80 to 100 atomic%, particularly 90 to 100%. Aluminum can also be used because it is inexpensive and has been used in compact discs.
Such a reflective layer 10 can be formed by a vacuum film forming method such as sputtering or vacuum evaporation. In this case, a technique is employed in which the degree of vacuum in the vacuum chamber is changed (for example, about 10 to 5 torr) to form a film having a different density or crystallization state, thereby increasing the reflectance of the reflective film. You can also.
[0034]
The protective layer 15 can be formed using an inorganic material such as SiO, SiN, or AlN, or an organic material such as a photocurable resin.
The inorganic protective layer can be formed by a vacuum film forming method, and the organic protective layer is formed by spinning a photocurable resin film (for example, SD1700, SD318, SD301 manufactured by Dainippon Ink and Chemicals, Inc.) on the reflective layer 10. After coating, it can be formed by irradiating resin curing light.
When a lens with a high NA is used to increase the density, the protective layer 15 needs to be light-transmitting. In general, to increase the NA, the thickness of the portion through which the reproduction light is transmitted must be increased. Need to be thin. This is due to an angle (a so-called tilt angle, which is proportional to the square of the product of the reciprocal of the wavelength of the light source and the numerical aperture of the objective lens) in which the disk surface deviates from the perpendicular to the optical axis of the optical pickup with the increase in NA. This is because the allowable amount of the generated aberration is small, and the tilt angle is easily affected by the aberration due to the thickness of the substrate.
[0035]
Therefore, the thickness of the protective layer is reduced and the light is irradiated from the protective layer side so that the influence of the aberration on the tilt angle is minimized.
In this case, for example, irregularities are formed on the substrate, a reflective layer is provided thereon, an upper heat-receiving layer, a light-absorbing layer, and a lower heat-receiving layer are sequentially stacked thereon, and a light-transmitting layer is further formed thereon. An optical recording medium for reproducing information from the recording layer by irradiating reproduction light from the protective layer side, or a reflective layer provided on a substrate, and a recording film formed thereon to form a recording layer. Further, there has been proposed an optical recording medium in which a cover layer having a light transmitting property is provided thereon, and reproducing information is irradiated from the cover layer side to reproduce information on the recording layer.
With this configuration, it is possible to cope with an increase in the NA of the objective lens by reducing the thickness of the protective layer or the cover layer. That is, by providing a thin protective layer or cover layer and recording / reproducing from this protective layer or cover layer side, it is possible to further increase the recording density.
Note that the protective layer or the cover layer is generally formed of a polycarbonate sheet or an ultraviolet curable resin.
[0036]
When a laser is applied to the write-once optical recording medium as described above, the laser beam heats the light absorbing layer 4, and this heat is transmitted to the lower heat receiving layer 3 and the upper heat receiving layer 5, and as a result, the light absorbing layer The area of the lower heat receiving layer 3 and / or the upper heat receiving layer 5 adjacent to the heated area of 4 causes a change in the thermal state of the material (melting, melting, decomposition, sublimation, etc.) and / or by heat Changes in the shape of the layer (expansion, depression, cavitation, irregularity deformation, etc.) occur.
Examples of the shape change of each layer will be described with reference to FIGS.
When the substrate 1 rises as shown in FIG. 3, when the shape does not change as shown in FIG. 4 or when the shape changes temporarily and finally becomes a shape without a shape change, as shown in FIG. May collapse.
The lower heat receiving layer 3 laminated on the substrate 1 changes its shape into a concave shape as shown in FIGS. 3 to 5 or forms a cavity as shown in FIG.
When the light absorbing layer 4 laminated on the lower heat receiving layer 3 changes to a convex shape as shown in FIG. 3, it does not change its shape as shown in FIG. In the case where the shape does not change, the shape may change to a concave shape as shown in FIG.
[0037]
The upper heat receiving layer 5 laminated on the light absorbing layer 4 changes its shape into a concave shape as shown in FIGS. 3 to 6, or forms a cavity as shown in FIG.
3 to 7 show the case where the shape of the reflective layer 10 does not change. However, in the recording portion, the light absorbing layer 4 generates heat by the laser beam, and the heat causes the lower heat receiving layer 3 to change shape. Due to the influence, the shape of the upper heat receiving layer 5 also changes, and the influence may reach the reflective layer 10 to change the shape of the reflective layer 10 (see FIGS. 8 and 9). The degree of the shape change at this time has a correlation with the heat generated from the light absorbing layer 4, and also changes depending on the type and thickness of the components of the light absorbing layer 4 and the upper heat receiving layer 5.
Further, at the recording portion, the quality of each layer is changed by heat. Particularly, in a layer containing a dye, a change in solubility and a change in optical characteristics occur due to decomposition of the dye.
8 and 9, the amount of the dye in the organic heat receiving layer corresponding to the central part of the recording spot decreases, and the portion indicated by the cross of “101” becomes like coke in appearance, and the dissolution characteristic is reduced. The case of causing a change in quality is shown.
[0038]
Next, the alteration of the coloring material contained in the heat receiving layer due to heat will be described.
The dye material receives heat from the light absorbing layer 4 or the dye itself absorbs light, and a part or all of the dye material undergoes a thermal state change such as decomposition, melting, and sublimation. As a result, the pigment material is usually deteriorated, and the deteriorated portion adheres to the reflective layer, and when peeled off at the upper heat receiving layer as a boundary, the deteriorated portion adheres preferentially to the reflective layer, and the non-transformed portion adheres to the light absorbing layer, respectively. And peeled off.
In this example, since the interface between the reflective layer and the upper heat-receiving layer is responsible for the reflection, adhesion of the altered pigment material to the reflective layer interface is important in controlling the reflected light from that portion.
Conversely, the adhesion changes due to the alteration, and the non-altered portion adheres to the reflective layer, and when the upper heat-receiving layer is separated, the non-altered portion has priority over the reflective layer and the altered portion has priority over the light-absorbing layer. In some cases, they are peeled off in close contact. In this case, the reflectivity may increase after recording.
[0039]
In addition, it is necessary to determine the recording power, the recording pulse length, and the type while checking the state and range of deterioration. The solubility of the pigment in the altered part changes because its structure is destroyed.
The change may occur in a direction in which the dye is difficult to dissolve, or in a case where the dye is decomposed to lower the molecular weight to increase the solubility, that is, in a direction in which the dye is easily dissolved. If there is a difference in the solubility between the deteriorated part and the non-transformed part, the range of the deterioration can be confirmed.
In this example, the direction in which the solubility of the deteriorated portion deteriorates and changes in a direction in which it hardly melts is a direction in which the reflectance is reduced, which is a change in optical properties due to a thermal state change (melting, decomposition, sublimation, etc.) of the dye. And was suitable.
[0040]
When confirming the solubility, the solvent is directly permeated into the deteriorated portion and the non-transformed portion, and the solubility is compared. Examples of the solvent used include esters such as butyl acetate and cellosolve acetate; ketones such as methyl ethyl ketone, cyclohexanone and methyl isobutyl ketone; chlorinated hydrocarbons such as dichloromethane, 1,2-dichloroethane and chloroform; amides such as dimethylformamide; cyclohexane Ethers such as tetrahydrofuran, ethyl ether and dioxane; alcohols such as ethanol, n-propanol, isopropanol and n-butanol diacetone alcohol; fluorine-based solvents such as 2,2,3,3-tetrafluoropropanol Glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and propylene glycol monomethyl ether; Can. The above-mentioned solvents can be used alone or in combination of two or more in consideration of the solubility of the dye used.
[0041]
When the recording is performed by irradiating light having a Gaussian distribution, heat-induced deterioration occurs in a heat receiving layer in a range where the light intensity is increased for recording, that is, a so-called recording mark area.
The recording mark area is a range obtained by irradiating and moving light having the following spot diameter r.
Here, the recording spot diameter r is a range represented by r = λ / NA × 0.82 (λ is a wavelength used for recording, NA is an aperture ratio of a lens). And good recording with little This is 1 / e ² (= 0.82).
Further, even when r = λ / NA, good recording with little jitter can be achieved by controlling the thickness of the heat receiving layer.
When r = λ / NA × 1.22, the reflectance of the unrecorded portion can be reduced, and the reflectance of the unrecorded portion can be controlled. This is the range of the so-called Airy image, and in this system, the range of the Airy image may be affected.
The range of heat-induced deterioration can be controlled by the heat conduction of the heat receiving layer. This control is appropriately adjusted based on the pit size and the electric signal obtained from the difference in solubility. In the present example, in particular, the change amount of the apparent optical characteristic of the unrecorded portion after recording is set to be within ± 50% as a relative value to the value of the optical characteristic of the unrecorded portion before recording. In this case, since the reflectance of the unrecorded portion does not change due to recording, a track-off or the like due to a change in the reflectance between the recording region and the non-recording region does not occur.
[0042]
Further, it is also possible to use a thermochromic dye for the upper heat receiving layer 5 and perform recording / reproducing using an optical change of the light absorbing layer 4 such as a change of an absorption coefficient.
Examples of the thermochromic dye to be used include spiropyran, fluoran, bianthrone, and triarylimidazole.
Further, light can be absorbed by the light absorbing layer 4, the light can be converted into electric energy, and recording can be performed on the upper heat receiving layer 5 by the electrochemical redox.
In that case, Ge, Si, GaAs, Gap, CdSe, CdS, ZnO, SnO, TiO, SiC, etc. can be used for the light absorbing layer 4, and the thionin dye, indigo dye, Tungsten oxide, merocyanine, phthalocyanine, squarylium, perylenetetracarboxylic acid, rhodamine, quinacridone, polyacetylene, poly (3-methylthiophene), and poly (N-methylpyrrole) can be used.
[0043]
Next, a second example of the write-once optical recording medium according to the present invention will be described with reference to FIG.
FIG. 10 is an enlarged sectional view of a main part. In this example, an intermediate layer 6 is provided between the upper heat receiving layer 5 and the reflective layer 10.
The intermediate layer 6 is provided for improving the adhesion between the upper heat receiving layer 5 and the reflective layer 10, improving the recording sensitivity, protecting the upper heat receiving layer 5, and the like. The same kind of hydrophilic resin as the heat receiving layer 3 or Ge, Si, GaAs, GaP, CdSe, CdS, ZnO, SnO, TiO, SiC, tungsten oxide, etc. which can be contained in the light absorbing layer 4 of the first example are used. It is possible.
When a hydrophilic resin is selected as the material of the intermediate layer 6, the aqueous solution is spin-coated on the upper heat receiving layer 5 to form the intermediate layer 6.
Also, in order to improve the water resistance and heat resistance of the intermediate layer 6, it is preferable to perform a crosslinking treatment or a crystallization treatment after spin coating. The crosslinking treatment and the crystallization treatment can be performed by the method described in the first example.
In addition, the transparent substrate 1, the lower heat receiving layer 3, the light absorbing layer 4, the upper heat receiving layer 5, the reflective layer 10, and the protective layer 15 are the same as those in the first example.
[0044]
Next, FIG. 11 shows a flowchart of an example of the manufacturing process of the write-once optical recording medium (disk) according to the present invention. Although each step is publicly known, it is briefly described as follows. Note that the hard coat layer forming step of S12 may be performed as needed. The intermediate layer forming step may be performed after S15, if necessary.
S1: Polish and wash the glass disk.
S2: Perform silane coating.
S3: A photoresist is spin-coated on the glass disk to form a resist layer having a predetermined thickness.
S4: Prebake is performed to blow off the solvent.
S5: The resist layer is irradiated with a laser through a condenser lens (cutting).
S6: The exposed glass disk is developed.
S7: The resist is heated above Tg to shape the groove shape (first bake).
S8: Baking is performed to solidify the pattern (second baking).
S9: Vapor deposition and plating are performed.
S10: A metal film is formed on the uneven surface of the glass disk, and the metal film is peeled to form a stamper.
S11: Injection molding is performed using a stamper to form a replica having a predetermined film thickness.
S12: A hard coat layer is formed on one side of the transparent substrate by a spin coating method. S13: A lower heat-receiving layer is formed on one surface of the transparent substrate by spin coating or sputtering.
S14: A light absorption layer is formed on the lower heat receiving layer by spin coating or sputtering.
S15: forming an upper heat receiving layer on the light absorbing layer.
S16: forming a reflective layer on the upper heat receiving layer.
S17: If necessary, another layer such as a protective layer is laminated to form a disk single plate. (When using as single veneer)
S18: If necessary, two single-plate disks obtained by laminating other layers such as a protective layer are laminated to form a double-sided disk.
S19: The disc is stored in the cartridge.
S20: The characteristics are evaluated.
In this flowchart, steps S7 and S8 can be performed simultaneously. Further, the shaping of the groove shape in the step S7 can be arbitrarily selected from a range of a heating temperature of 90 to 180 ° C. and a time of 5 to 90 minutes.
[0045]
The write-once optical recording medium of the present invention may be a single-sided, two-layer recording / reproducing medium. As a configuration thereof, a three-layer structure (hereinafter, referred to as a three-layer structure) including a lower heat receiving layer, a light absorbing layer, and an upper heat receiving layer is formed on each of two substrates, and the two are laminated with a transparent material. A laser beam is incident on one of the substrates, and information is recorded and reproduced on both three-layer structures. As the bonding material, a material having good flatness such as an ultraviolet curable resin or a double-sided tape is used.
In the write-once optical recording medium of the present invention, two or more sets of three-layer structures may be provided on one substrate. Its structure is to form two sets of three-layer structures on one substrate, and to record and reproduce information on both three-layer structures by injecting laser light from the substrate side or the opposite side of the substrate. It is.
In this case, if the three-layer structure formed on the substrate on which the recording / reproducing laser beam is incident is called a first set, and the three-layer structure on the opposite side is called a second set, information is recorded on the second set. For reproduction, the first set must transmit at least a part of the recording / reproduction laser beam.
[0046]
【Example】
Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In particular, although the embodiments are directed to a disk-shaped optical recording medium, the present invention can, of course, be applied to other forms of optical recording medium such as a card, a stick, and a tape.
From these examples, the layer structure and recording principle of the optical recording medium of the present invention are realized by a write-once optical recording medium made of an organic material corresponding to a blue laser wavelength, and further, a write-once optical recording medium capable of securing a high modulation degree. It turns out to be very effective.
[0047]
Example 1
A lower heat-receiving layer was formed on a polycarbonate substrate having a preformat pattern shown in FIGS. 1 and 2 by a spin coating method (average film thickness: 80 nm) using a material consisting of the following [Chemical Formula 1].
Next, as a light absorption layer, Te was formed to a thickness of 6 ± 2 nm by a sputtering method.
Next, an upper heat receiving layer was formed in a thickness of 50 ± 10 nm in the same manner as the lower heat receiving layer.
Further, as a reflective layer, Ag was formed to a thickness of 80 ± 20 nm by a sputtering method.
On this reflective layer, SD1700 (thermal conductivity: 1.0 or less) from Dainippon Ink and Chemicals, Inc. was laminated with a thickness of 5 μm to form a protective layer.
Using the optical disc evaluation device DDU-1000 (wavelength: 405 nm, NA: 0.65) manufactured by Pulstec Industrial Co., Ltd., recording was performed on the write-once optical recording medium manufactured as described above under the following conditions. Done.
As a result, a very clear signal with sufficiently large modulation was obtained for both the short mark and the long mark.
[0048]
Embedded image

[0049]
<Recording conditions>
Recording linear velocity: 6.0 (m / s)
Recording strategy: Basic strategy (basic strategy)
Ttop-Tmp = 1.40-0.75 (T)
Recording power: 11.0 (mW)
Recording pattern: 3T, 4T, 5T, 8T, 14T single period signal
The above recording conditions were determined while observing the recording portion of the recording medium. Specifically, when the medium was peeled off using the heat receiving layer as a boundary and observed with an optical microscope, the pigment material in the deteriorated portion was preferentially adhered to the reflective layer, and the non-transformed portion was preferentially adhered to the light absorbing layer side. Was. Further, ethanol was dropped on the reflection layer and the light absorption layer which were separated from each other with the heat receiving layer as a boundary, and the range of alteration was measured. The results were reflected in the recording conditions to find the above recording conditions.
FIG. 8 shows a section of the recording section when recording is performed on the land, and FIG. 9 shows a section of the recording section when recording is performed on the groove. In each of the drawings, 101 (the portion marked with a cross) indicates a portion in which the material of the lower heat receiving layer and the material of the upper heat receiving layer are altered. As can be seen from these drawings, in the present embodiment, the heat receiving layer The amount of the dye at the center of the recording spot was decreased, and the dissolution property was changed.
Here, the recording spot diameter r used is a range represented by r = λ / NA × 1.22 (Airy image).
In this medium, 10 or more pores having φ = 2 μm, four pores having φ = 5 μm, and one pore having φ = 10 μm are present in the light absorbing layer. ² In the range, there was a portion which was thinner than the average film thickness by 2% or more of the average film thickness, but the error was corrected by the player and good reproduction was possible.
In addition, even in a portion where no pore was present, a portion which was thinner than the average film thickness by 2% or more than the island-shaped average film thickness was confirmed. This portion was not closed cells but closed cells.
As described above, by confirming the shape of the recording portion and the degree of deterioration of the recording portion by the above-described method of confirming the deterioration, the reflectance of the recording portion when the reflectance of the unrecorded portion is set to 100 is 10 to 250. It can be adjusted arbitrarily within the range.
[0050]
Example 2
A write-once optical recording medium was produced in the same manner as in Example 1 except that SiC was formed as a light absorbing layer by sputtering, and recording was performed in the same manner as in Example 1. As a result, a clear signal was obtained. Was.
The light absorbing layer is made of Fe, Ti, Zr, Ta, Cr, Mo, W, Ni, Rh, Pd, Pt, Cu, Ag, Au, Zn, Al, In, Ge, Te, Sn, instead of SiC. Similar effects were obtained when a film was formed using at least one substance selected from the group consisting of Bi, Sb, Tl, and Pt.
[0051]
Example 3
On a substrate, a film of SiC is formed by a sputtering method, and an organic material layer made of a mixture of a cyanine dye of the following formula [2] and a merocyanine dye of the formula [3] is formed thereon by spin coating. A write-once optical recording medium was manufactured in the same manner as in Example 1 except that a lower heat receiving layer having a two-layer structure of 100 nm was formed, and the same recording as in Example 1 was performed. In both cases, a very clear signal having a sufficiently large modulation factor was obtained.
[0052]
Embedded image

Embedded image

[0053]
Example 4
On a substrate, a film of SiC is formed by a sputtering method, and on this substrate, tetra β- (1-benzimidazolyl) phthalocyanine, which is a kind of a phthalocyanine dye represented by the following general formula [Chemical Formula 4], and the following general formula [Chemical Formula 5] An organic material layer composed of a mixture with vanadyl-5,14,23,32-tetraphenyl-2,3-naphthalocyanine which is a kind of naphthalocyanine dye represented by the following formula: A write-once optical recording medium was prepared in the same manner as in Example 1 except that the lower heat receiving layer having the two-layer structure was formed, and recording was performed in the same manner as in Example 1. And a very clear signal with a sufficiently large modulation factor was obtained.
[0054]
Embedded image

Embedded image

[0055]
Example 5
On a substrate, a film of SiC is formed by a sputtering method, and R is a kind of azo dye represented by the following general formula [Chemical Formula 6]. ₁ ~ R ₆ A write-once optical recording medium was prepared in the same manner as in Example 1 except that an organic material layer composed of a dye of H = H was formed by a spin coating method, and a lower heat receiving layer having a two-layer structure with an average film thickness of 100 nm was formed. The recording was performed in the same manner as in Example 1, and a very clear signal was obtained for both the short mark and the long mark with sufficiently large modulation.
Embedded image

[0056]
Examples 6 to 8
An azobenzene fluorinated alcohol solution adjusted to 1% by weight is spin-coated on a polycarbonate substrate having a preformat pattern shown in FIGS. 1 and 2 so that the absorbance of azobenzene at λmax = 597 nm becomes 0.2. And a lower heat receiving layer (having a light absorbing property). The decomposition temperature of this azobenzene is 387 degrees.
Next, 5 nm (Example 6), 10 nm (Example 7), and 15 nm (Example 8) SiC films were formed on the lower heat receiving layer by a sputtering method to form light absorbing layers.
Next, on each light absorbing layer, a fluorinated alcohol solution of azobenzene adjusted to 1% by weight is spin-coated, and an upper heat receiving layer is formed so that the absorbance of azobenzene at λmax = 597 nm becomes 0.4. did.
Next, a silver film having a thickness of 100 nm was formed on each upper heat-receiving layer by a sputtering method to form a reflection layer.
Next, a photo-curable resin SD1700 (thermal conductivity: 1.0 or less) manufactured by Dainippon Ink and Chemicals, Inc. was laminated on each reflective layer to a thickness of 5 μm to form a protective layer.
The medium of Examples 6 to 8 produced as described above was irradiated with light having a wavelength of 405 nm and a film surface power of 10 mW, and recording was performed while rotating the medium at 6 m / s. The heat was absorbed and the lower heat receiving layer, upper heat receiving layer, and reflecting layer were deformed by the heat, and good recording in which a sufficient reflectance difference was obtained before and after recording could be performed.
[0057]
Examples 9 to 11
1 and 2 are spin-coated with a fluorinated alcohol solution of a cyanine dye adjusted to 1% by weight, and the absorbance of the cyanine dye at λmax = 632 nm becomes 0.2. Thus, a lower heat receiving layer (having light absorbing properties) was formed. The decomposition temperature of this cyanine dye is 160 degrees.
Next, SiC films having a thickness of 5 nm (Example 9), 10 nm (Example 10), and 15 nm (Example 11) were formed on the lower heat receiving layer by a sputtering method to form a light absorbing layer.
Next, a fluorinated alcohol solution of azobenzene was spin-coated on each light absorbing layer to form an upper heat receiving layer such that the absorbance of azobenzene at λmax = 597 nm was 0.4.
Next, a silver film having a thickness of 100 nm was formed on each upper heat-receiving layer by a sputtering method to form a reflection layer.
Next, a photo-curable resin SD1700 (thermal conductivity: 1.0 or less) manufactured by Dainippon Ink and Chemicals, Inc. was laminated on each reflective layer to a thickness of 5 μm to form a protective layer.
The medium of Examples 9 to 11 produced as described above was irradiated with light having a wavelength of 405 nm and a film surface power of 10 mW, and recording was performed while rotating the medium at 6 m / s. The heat was absorbed and the lower heat receiving layer, upper heat receiving layer, and reflecting layer were deformed by the heat, and good recording in which a sufficient reflectance difference was obtained before and after recording could be performed.
[0058]
Example 12
A silver film was formed on a polycarbonate substrate 1 having a preformat pattern shown in FIGS. 1 and 2 by a sputtering method to form a reflective layer, and a silver film was formed on the reflective layer by using the same dye as shown in Example 1. An organic material layer (corresponding to an upper heat receiving layer) is formed by spin coating (average film thickness: 100 nm), and an optical recording medium having a 12 nm-thick SiC light absorbing layer is formed thereon. Then, an organic material layer (corresponding to a lower heat-receiving layer) made of the dye represented by Chemical Formula 1 was formed by a spin coating method, and a 0.1-mm polycarbonate protective layer was further laminated thereon.
The complex refractive index at 405 nm is 1.485-i0.069, which is significantly lower than the complex refractive index required for the organic material used for the write-once optical recording medium. (For example, the complex refractive index of a dye used in a DVD-R near the recording / reproducing wavelength is about 2.5-i0.10).
The above optical recording medium was recorded under the following conditions using an optical disk evaluation device DDU-1000 manufactured by Pulstec Industrial Co., Ltd. As a result, both short marks and long marks had sufficiently large modulation and a very clear signal. was gotten.
<Recording conditions>
Recording linear density: 0.0917 (μm / bit)
Recording linear velocity: 6.0 (m / s)
Recording strategy: Basic strategy Ttop-Tmp =
1.40-0.75 (T)
Recording power: 11.0 (mW)
Recording pattern: 3T, 4T, 5T, 8T, 14T single period signal
[0059]
【The invention's effect】
According to the first to fifteenth aspects, it is possible to provide a write-once optical recording medium capable of performing good recording with a large capacity, a small wavelength dependency, and a small jitter.
Further, according to the third aspect of the invention, it is possible to provide a write-once optical recording medium having high contrast signal characteristics.
According to the eighth aspect of the present invention, it is possible to provide a write-once optical recording medium in which the recording shape can be easily grasped and the recording condition can be easily calculated.
Further, according to the twelfth aspect, it is possible to provide a write-once optical recording medium with good conversion of light to heat.
Further, according to the thirteenth aspect, it is possible to provide a write-once optical recording medium in which a recording layer can be multilayered.
According to the fourteenth aspect of the invention, it is possible to provide a write-once optical recording medium capable of obtaining a large contrast by deforming the reflective layer by heat generated from the light absorbing layer during recording.
According to the fifteenth aspect, a write-once optical recording medium protected from scratches, water, and the like can be provided.
[Brief description of the drawings]
FIG. 1 is an enlarged sectional view of a main part showing an example (first example) of a layer configuration of a write-once optical recording medium of the present invention.
FIG. 2 is a perspective view showing an example of the configuration of a write-once optical recording medium (optical disc) of the present invention.
FIG. 3 is an enlarged sectional view of a main part showing an example of a recording state of the write-once optical recording medium of the present invention.
FIG. 4 is an enlarged sectional view of a main part showing an example of a recording state of the write-once optical recording medium of the present invention.
FIG. 5 is an enlarged sectional view of a main part showing an example of a recording state of the write-once optical recording medium of the present invention.
FIG. 6 is an enlarged sectional view of a main part showing an example of a recording state of the write-once optical recording medium of the present invention.
FIG. 7 is an enlarged sectional view of a main part showing an example of a recording state of the write-once optical recording medium of the present invention.
FIG. 8 is an enlarged sectional view of a main part showing a state of deterioration of a heat receiving layer in a recording state of the write-once optical recording medium of the present invention (in the case of land recording).
FIG. 9 is an enlarged sectional view of a main part showing a state of deterioration of a heat receiving layer in a recording state of the write-once optical recording medium of the present invention (in the case of groove recording).
FIG. 10 is an enlarged cross-sectional view of a main part of a second example of the write-once optical recording medium of the present invention.
FIG. 11 is a flowchart of an example of a manufacturing process of a write-once optical recording medium (disk) of the present invention.
[Explanation of symbols]
1 Transparent substrate
1a Center hole
2 Preformat pattern
2a Guide groove
2b Pre-pit
2c Land part
3 Lower heat receiving layer
4 Light absorbing layer made of inorganic material
5 Upper heat receiving layer
6 middle class
10 Reflective layer
15 Protective layer
101 Changed part of pigment

Claims (15)

A write-once optical recording medium in which a lower heat-receiving layer, a light-absorbing layer made of an inorganic material, and an upper heat-receiving layer are provided in this order on a light-transmitting substrate, and further a reflection layer is provided directly or via an intermediate layer. In the above, the lower heat receiving layer and / or the upper heat receiving layer cause the material to undergo a thermal state change (melting, melting, decomposition, sublimation, etc.) at a lower temperature than the light absorbing layer and / or a shape change due to heat (Expansion, depression, cavitation, irregularity deformation, etc.). A write-once light in which an upper heat-receiving layer, a light-absorbing layer made of an inorganic material, a lower heat-receiving layer, a protective layer or a cover layer are provided in this order on a light-transmitting substrate, via a reflective layer, directly or via an intermediate layer. In the recording medium, the lower heat receiving layer and / or the upper heat receiving layer may cause the material to undergo a thermal state change (melting, melting, decomposition, sublimation, etc.) at a lower temperature than the light absorbing layer and / or A write-once optical recording medium characterized by causing a shape change (expansion, depression, cavitation, irregularity deformation, etc.). At least one of the lower heat-receiving layer, the light-absorbing layer made of an inorganic material, and the upper heat-receiving layer undergoes a shape change (expansion, depression, cavitation, irregularity, etc.) due to heat by light beam irradiation, thereby recording information. The recordable optical recording medium according to claim 1, wherein the recording is performed. The shape change is accompanied by a change in the film thickness of the lower heat-receiving layer and / or the upper heat-receiving layer, and the film thickness of at least a part of the information-recorded portion is smaller than the film thickness of the unrecorded portion. 4. The write-once optical recording medium according to claim 3, wherein: When recording by irradiating light showing a Gaussian distribution, the amount of the heat receiving layer material in the portion corresponding to the central portion of the Gaussian distribution is smaller than the amount of the heat receiving layer material in the portion corresponding to the outer peripheral portion of the Gaussian distribution. 5. The write-once optical recording medium according to claim 4, wherein the thickness of the lower heat receiving layer and / or the upper heat receiving layer changes. A cavity is formed at the interface between the lower heat receiving layer and / or the upper heat receiving layer and the light absorbing layer made of an inorganic material when recording is performed by irradiating a laser beam. The write-once optical recording medium according to any one of the above. The recording is performed by causing the lower heat-receiving layer and / or the upper heat-receiving layer to undergo a change in the melting characteristic of the material in the recording mark area due to a change in the thermal state of the material. 7. The write-once optical recording medium according to any one of 1 to 6. 8. The write-once optical recording medium according to claim 7, wherein the alteration in which the dissolution characteristic of the material changes is an alteration in a direction in which the solubility of the altered portion is reduced to make the material harder to dissolve. The lower heat receiving layer and / or the upper heat receiving layer is made of a material containing an organic substance having a decomposition temperature of 160 to 400 ° C, and the organic substance is an aromatic compound, an aliphatic compound, an amide, an ester, an amine, a urea. Or at least one selected from the group consisting of a sulfur compound and a hydroxy compound, or an anthraquinone-based, dioxidine-based, triphenodithiazine-based, phenanthrene-based, cyanine-based, phthalocyanine-based, naphthalocyanine-based, or merocyanine-based At least one selected from the group consisting of pyrylium, xanthene, triphenylmethane, croconium, azo, indigoid, methine, azulene, squarylium, sulfide and methanedithiolate dyes. In addition, it is not Write-once optical recording medium according to claim 1, characterized in that it comprises a 0.4 absorbance Te. The lower heat-receiving layer and / or the upper heat-receiving layer comprises an anthraquinone-based, dioxidin-based, triphenodithiazine-based, phenanthrene-based, cyanine-based, phthalocyanine-based, naphthalocyanine-based, merocyanine-based, pyrylium-based, xanthene-based, or triphenyl-based. In addition to at least one dye selected from the group consisting of methane-based, croconium-based, azo-based, indigoid-based, methine-based, azulene-based, squarylium-based, sulfide-based, and methanedithiolate-based dyes, a vinyl alcohol-based resin, 50% by weight of at least one polymer substance selected from the group consisting of vinyl acetate resin, acrylate resin, polyester resin, polyether resin, polystyrene resin, polyurethane resin, cellulose resin and fatty acid resin. Less than Write-once optical recording medium according to any one of claims 1 to 8, characterized in that a material having. 11. The write-once optical recording medium according to claim 1, wherein the lower heat receiving layer has a thickness of 5 to 1000 nm, and the upper heat receiving layer has a thickness of 5 to 200 nm. The light absorbing layer made of an inorganic material is made of Fe, Ti, Zr, Ta, Cr, Mo, W, Ni, Rh, Pd, Pt, Cu, Ag, Au, Zn, Al, In, Si, Ge, Te, Sn. The write-once optical recording medium according to any one of claims 1 to 11, comprising at least one selected from the group consisting of Bi, Sb and Tl, and having a thickness of 5 to 200 nm. 13. The write-once optical recording medium according to claim 1, wherein the reflective layer does not change in shape (expansion, formation of irregularities, etc.). The information is recorded by changing the shape (expansion, formation of irregularities, etc.) of the reflective layer by heat generated from the light absorbing layer made of an inorganic material when recording information by irradiating light. 13. The write-once optical recording medium according to any one of claims 12 to 12. The write-once optical recording medium according to claim 1, further comprising a protective layer on the reflective layer.

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