JP2004030864A - Write-once optical recording media - Google Patents

Abstract

An object of the present invention is to provide a simple layer structure, which can be manufactured at low cost, does not have a large limitation on the recording / reproducing wavelength, has a small wavelength dependence of recording characteristics, can obtain a relatively high reflectance, and can perform surface recording or recording with a high NA lens. In addition, it is possible to achieve a high density, and in recording and reproduction by deformation, the recording polarity does not change due to the recording mark length and recording power and is constant, and the reproduction waveform of the recording mark part shows a differential shape. To provide an optical recording medium with high recording polarity and high recording potential.
A laser device includes a deformable layer and a light absorbing layer, and an interface between the deformable layer and an adjacent layer in contact with the deformable layer on a laser light incident side is used as a main reflection interface. A write-once optical recording medium in which a recording mark is formed by deforming a deformable layer in a laser beam incident direction. Alternatively, an optical recording medium having a recording layer having both a function of absorbing laser light and a function of causing deformation without being melted or decomposed by irradiation with laser light.
[Selection] Fig. 35

Description

【化２】

【００７５】
実施例１０
溝深さ５５ｎｍの案内溝を有するポリカーボネート基板上に、上記〔化１〕で示される色素層を厚さ約４０ｎｍ、更にその上にＳｉＣを厚さ１０ｎｍ設けた光記録媒体を作製した。
この光記録媒体に対して、パルステック工業製の光ディスク評価装置、ＤＤＵ−１０００（波長：４０５ｎｍ、ＮＡ：０．６５）を用いて、ＳｉＣ側からレーザ光を照射して、ランド部（入射レーザ光側から見て、手前側にある溝位置）に、記録周波数６５．４ＭＨｚ、記録線速度６．０ｍ／ｓｅｃで８−１６変調の信号を記録パワーを変化させて記録した。
その結果、記録極性がＨｉｇｈ　ｔｏ　Ｌｏｗであり、図３３に示すような良好なジッタと変調度が得られた。
【００７６】
【発明の効果】
本発明１〜１４によれば、次のような特性を有する追記型光記録媒体を提供できる。
・単純層構成で、安価に製造可能である。
・記録再生波長に大きな制限がなく、記録特性の波長依存性が少ない。
・比較的高い反射率が得られる。
・変形を用いて記録再生を行う追記型光記録媒体であるが、記録マーク長や記録パワーによって記録極性が変化せず一定である。
・変形を用いて記録再生を行う追記型光記録媒体であるが、記録マーク部の再生波形が微分形状を示すことがない。
・変形を用いて記録再生を行う追記型光記録媒体であるが、記録極性がＨｉｇｈｔｏ　Ｌｏｗ記録となり易い。
・表面記録、或いは高ＮＡレンズによる記録に対応でき高密度化が達成できる。
【図面の簡単な説明】
【図１】参考例１の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図２】参考例２の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図３】参考例３の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図４】参考例４の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図５】参考例５の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図６】参考例６の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図７】参考例７の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図８】参考例８の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図９】溝パラメータの説明図。
（ａ）　変形した記録マークを説明するための図（Ｆｒｏｍ　Ｓｕｂ）。
（ｂ）　変形した記録マークを説明するための図（Ｆｒｏｍ　Ａｉｒ）。
【図１０】実施例１の、ランド部にＰｉｔが形成された記録部を基板側から再生した場合の計算結果を示す図。
【図１１】実施例１の、ランド部にＢｕｍｐが形成された記録部を基板側から再生した場合の計算結果を示す図。
【図１２】実施例１の、グルーブ部にＰｉｔが形成された記録部を基板側から再生した場合の計算結果を示す図。
【図１３】実施例１の、グルーブ部にＢｕｍｐが形成された記録部を基板側から再生した場合の計算結果を示す図。
【図１４】実施例１の、ランド部にＰｉｔが形成された記録部をＳｉ側から再生した場合の計算結果を示す図。
【図１５】実施例１の、ランド部にＢｕｍｐが形成された記録部をＳｉ側から再生した場合の計算結果を示す図。
【図１６】実施例１の、グルーブ部にＰｉｔが形成された記録部をＳｉ側から再生した場合の計算結果を示す図。
【図１７】実施例１の、グルーブ部にＢｕｍｐが形成された記録部をＳｉ側から再生した場合の計算結果を示す図。
【図１８】実施例２の、基板上にＳｉを設けた場合であって、ランド部にＰｉｔが形成された記録部を基板側から再生した場合の計算結果を示す図。
【図１９】実施例２の、基板上にＳｉを設けた場合であって、グルーブ部にＰｉｔが形成された記録部を基板側から再生した場合の計算結果を示す図。
【図２０】実施例２の、基板上にＳｉを設けた場合であって、ランド部にＢｕｍｐが形成された記録部をＳｉ側から再生した場合の計算結果を示す図。
【図２１】実施例２の、基板上にＳｉを設けた場合であって、グルーブ部にＢｕｍｐが形成された記録部をＳｉ側から再生した場合の計算結果を示す図。
【図２２】実施例２の、基板上にＳｉＣを設けた場合であって、ランド部にＰｉｔが形成された記録部を基板側から再生した場合の計算結果を示す図。
【図２３】実施例２の、基板上にＳｉＣを設けた場合であって、グルーブ部にＰｉｔが形成された記録部を基板側から再生した場合の計算結果を示す図。
【図２４】実施例２の、基板上にＳｉＣを設けた場合であって、ランド部にＢｕｍｐが形成された記録部をＳｉＣ側から再生した場合の計算結果を示す図。
【図２５】実施例２の、基板上にＳｉＣを設けた場合であって、グルーブ部にＢｕｍｐが形成された記録部をＳｉＣ側から再生した場合の計算結果を示す図。
【図２６】実施例３の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図２７】実施例４の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図２８】実施例５の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図２９】実施例６の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図３０】実施例７の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図３１】実施例８の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図３２】実施例９のアイパターンを示す図。
【図３３】実施例１０のジッタと変調度を示す図。
【図３４】基板上に光吸収層と変形層を有する本発明の実施の形態例を示す図。
【図３５】図３４の追記型光記録媒体であって、変形層と、該変形層の光吸収層側と反対側の隣接層との界面が主反射界面である場合の記録例（変形例）を示す図。
【図３６】図３４の追記型光記録媒体であって、変形層と光吸収層との界面が主反射界面である場合の記録例（変形例）を示す図。
【図３７】基板上に変形層と光吸収層を有する本発明の実施の形態例を示す図。
【図３８】図３７の追記型光記録媒体であって、変形層と光吸収層との界面が主反射界面である場合の記録例（変形例）を示す図。
【図３９】図３７の追記型光記録媒体であって、変形層と基板との界面が主反射界面である場合の記録例（変形例）を示す図。
【図４０】基板上に記録層を有する本発明の実施の形態例を示す図。
【図４１】図４０の追記型光記録媒体であって、記録層と、該記録層の基板側と反対側の隣接層との界面が主反射界面である場合の記録例（変形例）を示す図。
【図４２】図４０の追記型光記録媒体であって、記録層と基板との界面が主反射界面である場合の記録例（変形例）を示す図。
【図４３】基板上に有機材料層と記録層を有する本発明の実施の形態例を示す図。
【図４４】図４０の追記型光記録媒体であって、記録層と、該記録層の有機材料層と反対側の隣接層との界面が主反射界面である場合の記録例（変形例）を示す図。
【図４５】図４０の追記型光記録媒体であって、記録層と有機材料層との界面が主反射界面である場合の記録例（変形例）を示す図。
【図４６】従来のディスクの層構成を示す図。
【図４７】マーク長記録の記録マークを再生した場合の再生信号の波形を説明する図。
（ａ）　一般的な場合
（ｂ）　記録マークの前後エッジ近傍で変極点を持つ微分波形
（ｃ）　記録マークの中心近傍で変極点を持つ微分波形
【図４８】基板上に有機材料層、Ｓｉ層が積層された光記録媒体であって、記録再生が基板側から行われる場合の、ポインティングベクトルの計算結果を示す図。
【図４９】基板上に有機材料層、Ｓｉ層が積層された光記録媒体であって、記録再生がＳｉ層側から行われる場合の、ポインティングベクトルの計算結果を示す図。
【符号の説明】
Ｍａｒｋ　Ｌｅｎｇｔｈ　マーク長
Ｔ　基準クロック
ＲＦ　Ｌｅｂｅｌ（Ｖ）　ＲＦ（再生信号）レベル（ボルト）
Ｍｏｄｕｌａｔｅｄ　ａｍｐｌｉｔｕｄｅ　変調度
Ｕｎｒｅｃ　未記録時の再生信号（ＲＦ）レベル
Ｔｏｐ　マーク列を記録した時の最大再生信号レベル（即ちスペース部）
Ｂｏｔｔｏｍ　マーク列を記録した時の最小再生信号レベル（即ちマーク部）
ＭＡ　（Ｔｏｐ−Ｂｏｔｔｏｍ）／Ｔｏｐで計算される変調度
Ｔｉｍｅ０．５（μｓ／ｄｉｖ）　時間（１メモリ０．５マイクロ秒）
Ｓｕｍ　Ｓｉｇｎａｌ　和信号（再生信号）
Ｂｅａｍ　Ｐｏｓｉｔｉｏｎ（μｍ）　ビーム位置（マーク中心からのビーム中心のズレ量（マイクロメートル）
Ａ　基準点から隣接するランド又はグルーブの近い方の端部までの幅
Ｂ　基準点から隣接するランド又はグルーブの遠い方の端部までの幅
Ｃ　基準点から次のグルーブ又はランドの近い方の端部までの幅
Ｄ　基準点から次のグルーブ又はランドの遠い方の端部までの幅
ζ　グルーブ底部からランド上面までの高さ
Ｐｉｔ　レーザ光の入射方向とは逆に変形した記録マーク
Ｂｕｍｐ　レーザ光の入射方向に変形した記録マーク
Ｆｒｏｍ　Ｓｕｂ　基板側から
Ｆｒｏｍ　Ａｉｒ　反基板側から
σ／Ｔｗ　ジッタ
Ｚ　ｐｏｓｉｔｉｏｎ　層方向の位置（有機材料層とＳｉ層の厚さを示す）
Ｙ　ポインティングベクトル（ポインティングベクトルの時間平均値）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a write-once read-many (WORM) optical recording medium, and more particularly to a write-once optical recording medium capable of high-density recording even with light in a blue laser wavelength region of about 350 to 500 nm.
[0002]
[Prior art]
◎ About write-once optical recording media compatible with blue laser
The development of a blue laser capable of recording at a very high density is progressing rapidly, and a write-once optical recording medium corresponding to the development is being developed.
In conventional write-once optical recording media, recording pits are formed by irradiating a laser beam to a recording layer made of an organic material and causing a change in refractive index mainly due to decomposition and alteration 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, it is necessary to select an appropriate material having an optical property and a decomposition behavior with respect to a blue laser wavelength as the organic material used for the recording layer. In other words, the recording / reproducing wavelength is set to a large absorption band in order to increase the reflectance at the time of non-recording and to cause the organic material to be decomposed by laser irradiation to cause a large change in the refractive index (this provides a large degree of modulation). It is selected so as to be located on the long wavelength side skirt.
This is because the bottom of the large absorption band of the organic material on the long wavelength side is a wavelength region having an appropriate absorption coefficient and obtaining a large refractive index.
[0003]
However, an organic material having optical properties with respect to the wavelength of a blue laser having a value comparable to that of a conventional blue laser has not yet been found. This means that in order to obtain an organic material having an absorption band 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 blue laser wavelength, and the absorption coefficient can be controlled. However, since the organic material does not have a large refractive index, a large degree of modulation cannot be obtained.
Examples of the organic material corresponding to a blue laser include those described in JP-A-2001-181524, JP-A-2001-158865, JP-A-2000-343824, JP-A-2000-343825, and JP-A-2000-335110. is there.
However, in these publications, the examples only measure the spectra of the solution and the thin film, but do not describe recording and reproduction.
In each of JP-A-11-221964, JP-A-11-334206 and JP-A-2000-43423, recording is described in Examples, but the recording wavelength is 488 nm, and the recording condition and recording density are not described. However, there is only a statement that good recording pits were formed.
[0004]
In JP-A-11-58955, although recording is described in Examples, the recording wavelength is 430 nm, and there is no description about recording conditions or recording density, and there is a description that a good degree of modulation was obtained. Only.
JP-A-2001-39034, JP-A-2000-149320, JP-A-2000-113504, JP-A-2000-108513, JP-A-2000-222772, JP-A-2000-218940, JP-A-2000-222277, In JP-A-2000-158818, JP-A-2000-280621, and JP-A-2000-280620, there are examples of recording at a recording wavelength of 430 nm and NA of 0.65 in the examples, but low recording with the shortest pit of 0.4 μm. Density condition (recording density equivalent to DVD).
In Japanese Patent Application Laid-Open No. 2001-146074, the recording / reproducing wavelength is 405 to 408 nm, but there is no specific description about the recording density, and the recording condition is the low recording density of 14T-EFM signal recording.
[0005]
Further, regarding the layer configuration and recording method different from those of the conventional CD and DVD optical recording media, the following techniques are disclosed.
Japanese Patent Application Laid-Open No. 7-304258 discloses a technique of performing recording by changing the extinction coefficient (absorption coefficient in the present invention) of a saturable absorbing dye in a layer structure of a substrate / saturable absorbing dye-containing layer / reflective layer. It has been disclosed.
Japanese Patent Application Laid-Open No. 8-83439 discloses a technique in which recording is performed by discoloring or deforming a metal-deposited layer by heat generated by the light-absorbing layer in a layer structure of a substrate / metal-deposited layer / light-absorbing layer / protective sheet. Is disclosed.
Japanese Patent Application Laid-Open No. 8-138245 discloses that recording is performed by changing the depth of a groove portion by changing the film thickness of a recording layer in a layer structure of a substrate / dielectric layer / recording layer including a light absorber / reflection layer. The technology is disclosed.
Japanese Patent Application Laid-Open No. 8-2977838 discloses a technique of performing recording by changing the thickness of a recording layer by 10 to 30% in a layer structure of a substrate / a recording layer including a light absorber / a metal reflection layer. I have.
[0006]
Japanese Unexamined Patent Publication No. Hei 9-198714 discloses a layer structure of a substrate / a recording layer containing an organic dye / a metal reflective layer / a protective layer, in which the groove width of the substrate is increased by 20 to 40% with respect to an unrecorded portion. A technique for performing recording is disclosed.
Japanese Patent No. 2506374 discloses a technique in which recording is performed by forming a bubble by deforming a metal thin film in a layer structure of a substrate / intermediate layer / metal thin film.
Japanese Patent No. 2591939 has a layer structure of substrate / light absorbing layer / recording auxiliary layer / light reflecting layer, in which the recording auxiliary layer is deformed into a concave shape and the light reflecting layer is formed into a concave shape along with the deformation of the recording auxiliary layer. There is disclosed a technique of performing recording by deforming.
Japanese Patent No. 2591940 discloses a recording assisting device having a layer structure of substrate / light absorbing layer / porous recording auxiliary layer / light reflecting layer or substrate / porous recording auxiliary layer / light absorbing layer / light reflecting layer. There is disclosed a technique in which recording is performed by deforming a layer in a concave shape and deforming a light reflecting layer in a concave shape along with the deformation of the recording auxiliary layer.
Japanese Patent No. 2591941 discloses that a light absorbing layer is deformed in a concave shape along with a light absorbing layer and a light reflecting layer is deformed in a concave shape in accordance with the deformation of the light absorbing layer. There is disclosed a technique of performing recording by causing the recording to be performed.
[0007]
Japanese Patent No. 2982925 discloses that a recording / assisting layer and an organic dye are compatible with each other in a layer structure of a substrate / a recording layer containing an organic dye / a recording auxiliary layer, and the absorption spectrum of the organic dye is shifted to a shorter wavelength side. Discloses a technique for performing recording.
Japanese Patent Application Laid-Open No. 9-265660 discloses a layer configuration in which a composite function layer having a function of a reflective layer and a recording layer and a protective layer are sequentially formed on a substrate. Recording is performed by forming bumps between the substrate and the composite function layer. Performing techniques are disclosed. Note that the composite functional layer is defined as a metal such as nickel, chromium, or titanium, or an alloy thereof.
Japanese Patent Application Laid-Open No. Hei 10-134415 discloses a layer structure in which a metal thin film layer, a deformable buffer layer, a reflective layer, and a protective layer are sequentially formed on a substrate, and the substrate and the metal thin film layer are deformed at the same time. A technique for performing recording by reducing the thickness of the buffer layer is disclosed. The metal thin film layer is defined as a metal such as nickel, chromium, and titanium, or an alloy thereof. Further, it is described that a resin which is easily deformable and has an appropriate fluidity is used for the buffer layer, and a dye may be contained in the buffer layer to promote the deformation.
[0008]
Japanese Patent Application Laid-Open No. H11-306591 discloses a layer configuration in which a metal thin film layer, a buffer layer, and a reflective layer are sequentially laminated on a substrate, in which the substrate and the metal thin film layer are deformed. A technique for performing recording by changing an optical constant is disclosed. Note that the metal thin film layer is preferably made of a metal such as nickel, chromium, or titanium, or an alloy thereof. The buffer layer is made of a mixture of a dye and an organic polymer, and a dye having a large absorption band near the recording / reproducing wavelength is used.
Japanese Patent Application Laid-Open No. H10-124926 discloses a layer configuration in which a metal recording layer, a buffer layer, and a reflective layer are sequentially laminated on a substrate, in which the substrate and the metal recording layer are deformed. A technique for performing recording by changing an optical constant is disclosed. It is described that a metal such as nickel, chromium, and titanium, or an alloy thereof is preferable for the metal recording layer. The buffer layer is made of a mixture of a dye and a resin, and a dye having a large absorption band near the recording / reproducing wavelength is used.
[0009]
As described above, the above various prior arts do not aim at realizing a write-once optical recording medium in the blue laser wavelength region, and are not effective layer configurations and recording methods in the blue laser wavelength region.
In particular, in the vicinity of 405 nm, which is the center of the oscillation wavelength of a blue semiconductor laser currently in practical use, almost all organic materials having an optical constant similar to the optical constant required for the recording layer of the conventional write-once optical recording medium are almost used. Almost no. 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, most of the embodiments in the above-mentioned conventional technology are experiments with a conventional disk configuration (see FIG. 46). Although a configuration different from the conventional disk configuration has been proposed, the dye used therein is The same optical characteristics and functions as in the past are required, and there is no effective proposal for a layer configuration, a recording principle, and a recording method that can easily realize a write-once optical recording medium made of an organic material in a blue laser wavelength region.
[0010]
In addition, in a conventional write-once optical recording medium using an organic material, a large refractive index and a relatively small absorption coefficient (approximately 0.05 to 0.07) with respect to the recording / reproducing wavelength are obtained from the viewpoint of securing the degree of modulation and reflectance. Only organic materials with a) can be used.
That is, since the organic material does not have a sufficient absorbing ability to the recording light, it is impossible to reduce the thickness of the organic material, and therefore, it is necessary to use a substrate having a deep groove. (Because the organic material is usually formed by a spin coating method, the organic material is buried in a deep groove to increase the thickness). Therefore, it is very difficult to form a substrate having a deep groove, which has been a factor of deteriorating the quality as a write-once optical recording medium. Further, in a conventional write-once optical recording medium using an organic material, the main absorption band of the organic material exists near the recording / reproducing wavelength, so that the wavelength dependence of the optical constant of the organic material increases (the optical constant depends on the wavelength). The problem is that the recording characteristics such as recording sensitivity, modulation degree, jitter, and error rate, and the reflectivity change significantly with respect to fluctuations in the recording / reproducing wavelength due to individual differences in lasers, changes in environmental temperature, etc. was there.
[0011]
◎ General recording principle of write-once optical recording media
In general, in a write-once optical recording medium, a recording mode due to a change in the optical constant of the material used for the recording layer (the real part of the complex refractive index and the film thickness of the recording layer material) and the substrate and the reflective layer are deformed. There are deformation modes, which form recording marks. For example, Japanese Patent No. 271040 and Japanese Patent No. 2840643 describe the recording principle of a write-once optical recording medium.
However, these publications do not specifically describe how the described recording principle (recording mode) contributes to a reproduced signal and do not describe experimental results. That is, in the embodiments, it has not been demonstrated that recording is performed mainly by the recording principle recited in the claims.
Although it is very difficult to limit (specify) the recording mode in a multi-layered recording medium, it is observed by SEM or AFM that the recording was made according to the recording principle recited in the claims. However, this only proves that the claimed recording principle may exist and that it may contribute to the reproduced signal.
[0012]
Also, there is no description of what kind of reproduced signal is actually generated and what merits it has with respect to the conventional recording principle and other recording principles. Absent).
In an application in which the recording principle was invented, in some publications, examples are described in the form of embodiments, but even if the recording principle is clear, the relationship between the recording principle and the reproduced signal is not Since it is not clear, a specific example in which the relationship between the recording principle and the reproduction signal is clarified is necessary, and it cannot be described simply in the form of an embodiment.
Further, in almost all of the embodiments in the publications, a signal of a single cycle is recorded in a recording example (recording experiment), and it is completely unknown what happens to recording of different recording mark lengths. That is, there is no result that a random signal can be recorded and a beautiful eye pattern is obtained.
[0013]
For example, it should be described at least as to whether a mark sufficiently smaller than the beam diameter of the recording laser can be recorded and reproduced, what the recording polarity is, and what the recording waveform will be.
Since the reproduction signal of the optical recording medium is obtained by the diffraction effect together with the interference effect, for example, the height of the recording mark or the depth of the recording area (the thickness direction of the optical recording medium) is independent of the recording mark length. Even if it is assumed to be constant, the relationship between the recording mark length and the beam diameter of the laser beam changes depending on the recording mark length, so it cannot be said unconditionally how the reproduction signal changes.
Even if a signal of a single cycle can be recorded, there are not many cases where a random pattern signal can be recorded (conversely, it is not an exaggeration to say that it is rare).
In many cases, only the degree of modulation is described as a result of recording, but using only the degree of modulation does not prove that the medium can be used as an optical recording medium.
The above will be described with a specific example.
[0014]
An optical recording medium in which SiC was provided with a thickness of 10 nm on a polycarbonate substrate having a guide groove was manufactured.
The optical recording medium was irradiated with a laser beam of 6.0 mW from the substrate side using a DDU-1000 (wavelength: 405 nm, NA: 0.65) optical disc evaluation device manufactured by Pulstec Industrial. 3T to 14T marks were individually recorded at a recording frequency of 65.4 MHz and a recording linear velocity of 6.0 m / s in the portion (groove position on the back side when viewed from the incident laser beam side).
At this time, the results of measuring the dependence of the reproduction signal (RF level) on the recording mark length (Mark Length) are shown in FIGS. 3 (a) to 3 (d).
In FIG. 3A, Unrec is a reproduction signal (RF level) when no recording is performed, Top is a maximum reproduction signal level (that is, a space portion) when a mark string is recorded, and Bottom is a minimum reproduction when a mark string is recorded. The signal level (that is, the mark portion), and further, MA indicates the modulation degree calculated by (Top-Bottom) / Top.
Referring to FIG. 3A, it can be seen that although the degree of modulation is slightly small, the reproduction signal (RF level) has a recording mark length (Mark Length) dependency that is equivalent to that of a CD-R or DVD-R. .
[0015]
However, in this optical recording medium, a random pattern can be recorded in the same manner as a CD-R or DVD-R, and a reproduction signal corresponding to a mark length cannot be obtained.
FIG. 3B shows a reproduction signal when a 3T mark is continuously recorded, a reproduction signal when a 4T mark is continuously recorded, and a reproduction signal level when no recording is performed. FIG. 3D shows a reproduction signal when the 6T mark is continuously recorded, a reproduction signal when the 8T mark is continuously recorded, and a reproduction signal level when the recording is not performed. , The reproduction signal when the 14T mark was continuously recorded, and the reproduction signal level when no recording was performed.
As a result, in FIG. 3 (b) and FIG. 3 (c), a reproduced signal according to the mark length similar to that of a CD-R or a DVD-R is obtained apart from signal disturbance. In (d), a reproduction signal corresponding to the mark length is not obtained as in the case of the CD-R or DVD-R. That is, in the 14T signal, the RF level at the center of the mark greatly increases and exceeds the RF level at the time of no recording.
[0016]
As in the case of CD-R and DVD-R, it is clear that the 14T signal shown in FIG. 3D cannot be correctly reproduced by the reproduction method in which the mark length of the reproduction signal is determined based on the slice level [ Should be determined, but it is determined as a pattern of (5T mark)-(4T space)-(5T mark)]. In other words, simply saying that recording could be performed does not mean that it can be actually used as an optical recording medium. [At a glance, a High to Low signal is obtained as shown in FIG. This does not mean that mark length recording is possible.]
Actually, there are a great number of materials and layer configurations that can be used for recording, but only very few can be used as optical recording media.
Therefore, even in the publications cited as the prior art, only the experimental results of the expression that the recording was performed, the experimental results of judging whether or not the recording is possible by the value of the macroscopic modulation degree, or the experimental results of the recording of a single cycle are available. In the publications not described, it cannot be determined whether or not the effect of the invention is truly achieved.
[0017]
[Problems to be solved by the invention]
An object of the present invention is to provide a write-once optical recording medium having the following characteristics.
-It can be manufactured at low cost with a simple layer configuration.
-There is no great limitation on the recording / reproducing wavelength, and the wavelength dependence of the recording characteristics is small.
-A relatively high reflectance is obtained.
Even when recording / reproducing is performed using deformation, the recording polarity does not change depending on the recording mark length or recording power and is constant.
-Even when recording and reproduction are performed using deformation, the reproduction waveform of the recording mark portion does not show a differential shape.
-Even in the case where recording and reproduction are performed using deformation, the recording polarity tends to be High to Low recording.
-Surface recording or recording with a high NA lens can be performed, and high density can be achieved.
[0018]
[Means for Solving the Problems]
The above-mentioned problems are solved by the following inventions 1) to 14) (hereinafter, referred to as inventions 1 to 14).
1) At least a deformable layer and a light absorbing layer, and an interface between the deformable layer and an adjacent layer on the laser light incident side in contact with the deformable layer is set as a main reflection interface. A write-once optical recording medium, wherein a recording mark is formed by deforming a deformable layer in a laser beam incident direction.
2) The write-once optical recording medium according to 1), wherein the deformable layer and an adjacent layer on the laser beam incident side that is in contact with the deformable layer are not mixed by recording.
3) Near the interface between the deformed layer and the layer located on the back side of the deformed layer as viewed from the laser beam incident side, a reduced refractive index portion or a void portion of the material forming the layer present on the back side is formed. A write-once optical recording medium according to 1) or 2), wherein a recording mark is formed by forming the recording mark.
4) The write-once optical recording medium according to 1) or 2), wherein a recording mark is formed by forming a reduced refractive index portion or a void portion of a material constituting the deformable layer in the deformable layer. .
5) The write-once optical recording medium according to any one of 1) to 4), wherein the light absorption layer is made of an organic material.
6) The write-once optical recording medium according to any one of 1) to 4), wherein the light absorption layer contains Si and / or Ge.
7) A write-once type having at least a recording layer, wherein the recording layer has both a light absorbing function for laser light and a deformation function for causing deformation without being melted or decomposed by irradiation with laser light. Optical recording medium.
8) At least a recording layer, which has both a function of absorbing laser light and a function of causing deformation without being melted or decomposed by irradiation of laser light. The interface between the recording layer and the adjacent layer on the laser light incident side that is in contact with the recording layer is defined as the main reflection interface, and the recording layer itself is deformed in the laser light incident direction due to the heat generation of the recording layer by the irradiation of the laser light, thereby forming a recording mark. A write-once optical recording medium, comprising:
9) It has at least a recording layer and an organic material layer, and the recording layer has both a function of absorbing laser light and a function of causing deformation without being melted or decomposed by irradiation with laser light. Write-once optical recording medium.
10) It has at least a recording layer and an organic material layer, and the recording layer has both a light absorbing function for laser light and a deformation function for causing deformation without being melted or decomposed by irradiation with laser light. The interface between the layer and the adjacent layer on the laser light incident side that is in contact with the recording layer is used as the main reflection interface, and the recording layer itself is deformed in the direction of incidence of the laser light due to heat generation of the recording layer by irradiation with the laser light. A write-once optical recording medium, wherein a mark is formed.
11) In the vicinity of the interface between the recording layer and the layer existing on the back side of the recording layer when viewed from the laser beam incident side, a portion having a lower refractive index or a void portion of the material constituting the layer existing on the back side is provided. The recordable optical recording medium according to any one of 7) to 10), wherein a recording mark is formed by forming the recording mark.
12) Additional recording according to any one of 7) to 10), wherein a recording mark is formed by forming a reduced refractive index portion or a void portion of a material constituting the recording layer in the recording layer. Type optical recording medium.
13) The write-once optical recording medium according to any one of 7) to 12), wherein the recording layer contains Si and / or Ge.
14) The recordable optical recording medium according to any one of 1) to 13), wherein a recording mark can be formed by a blue laser beam having a wavelength of 350 to 500 nm.
[0019]
Hereinafter, the present invention will be described in detail, the relationship between the principle of recording and reproduction according to the present invention and the reproduced signal will be clarified, and the validity and validity of the present invention will be clearly shown.
The inventor of the present invention tends to easily change the recording polarity from low to high, change the recording polarity depending on the recording mark length or recording power, or differentiate the reproduced signal waveform in the following cases a) and b). I found that.
B) A case where there is a main reflection interface at the interface between the layer to be deformed and the layer adjacent to the laser light incident side of the layer to be deformed, and the main reflection interface is deformed in the direction opposite to the incident laser light side (light source side).
B) In the case of b), particularly, a case where a deformable layer and a refractive index lowering portion or a void portion are formed near the interface of the layer adjacent to the laser beam incident side of the deformable layer.
That is, in the vicinity of the interface between the layer to be deformed and the layer adjacent to the side opposite to the direction in which the deformation occurs, separation of the layers, the volume expansion of the layer adjacent to the side opposite to the direction in which the deformation occurs, or Due to the melting, decomposition, explosion, etc. of the layer adjacent to the side opposite to the direction in which the deformation occurs, a portion having a reduced refractive index such as a void is likely to be formed, which causes the recording polarity to become low to high, the recording mark length and the recording length. It has been found that a change in recording polarity due to power or a differentiation of a reproduction signal waveform is caused. The recording polarity is changed from low to high, a change in recording polarity due to a recording mark length or recording power, or a differentiation of a reproduction signal waveform. In order to prevent the laser beam from being deformed, the deformation direction of the main reflection interface is controlled so that a portion having a low refractive index such as a void is formed on the deep side of the main reflection interface when viewed from the laser beam incident side, or recording / reproducing. Control the direction Was found to be very effective.
[0020]
Therefore, in the present invention, the layer to be deformed (the deformed layer or the recording layer in the present invention) is deformed toward the incident laser beam side (light source side).
Thereby, the refractive index lowering portion or the air gap can be formed on the deep side of the main reflection interface (that is, the deformed interface) when viewed from the laser beam incident side, and the recording polarity is changed from Low to High. The recording polarity change due to the recording mark length and recording power or the differentiation of the reproduction signal waveform is suppressed and prevented, the recording polarity can be unified to High to Low, and good mark length recording / reproduction can be realized.
In general, in mark length recording, when a recorded mark is reproduced, a reproduced signal (RF signal) as shown in FIG. 47A is obtained, whereas a reproduced signal as shown in FIG. 47B or FIG. In the present invention, a signal having an inflection point near the leading and trailing edges of the recording mark and near the center of the recording mark is referred to as a differential waveform (differential waveform).
[0021]
The term “deformed layer and adjacent layer in contact with the deformed layer” as used in the present invention indicates, for example, a substrate or an overcoated layer in the case of an optical recording medium configuration in which a deformed layer and an overlaid layer are sequentially provided on a substrate ( For example, the overcoat layer may be an air layer).
In addition, the main reflection interface referred to in the present invention refers to a reflection interface that contributes the most to reflected reproduction light. Therefore, the main reflection interface is generally the interface having the largest reflection coefficient.
However, even at the interface having the largest reflection coefficient, there are a plurality of layers on the incident light side from the reflection interface or the absorption coefficient (complex refractive index of the layer) on the incident light side of the reflection interface. This does not apply when sufficient light does not pass through to the interface having the largest reflection coefficient, such as when the imaginary part is large.
Therefore, the reflection interface that contributes the most to the reproduction reflection light is referred to as the main reflection interface.
[0022]
For example, when a deformed layer having a large complex refractive index is sandwiched between adjacent layers having a smaller complex refractive index than the deformed layer, the interface between the deformed layer and one of the adjacent layers is a main reflection interface. The main reflection interface referred to above indicates an interface having a larger pointing vector. Here, the pointing vector indicates a time average value of the pointing vector, and is a value indicating the light intensity.
As a specific example, an organic material layer (assuming a complex refractive index of 2.0-i0.1 and a film thickness of 60 nm) and a Si layer (a complex refractive index of 4.3-i2.0 and a film thickness of 20 nm) are provided on a substrate. Considering the case where recording and reproduction are performed from the substrate side, the main reflection interface is located at one of the adjacent layer interfaces of the Si layer.
The interface having the largest reflection coefficient is the interface between the Si layer and the air layer, and the interface having the largest reflection coefficient is the interface between the organic material layer and the Si layer. When the pointing vector is calculated, the result is as shown in FIG. The interface between the organic material layer having a large pointing vector and the Si layer is the main reflection interface in the present invention.
[0023]
As another specific example, an organic material layer (assuming a complex refractive index of 2.0-i0.1 and a film thickness of 60 nm) and a Si layer (complex refractive index of 4.3-i2.0, Considering a case where an optical recording medium having a thickness of 20 nm is stacked and recording / reproducing is performed from the Si layer side, the main reflection interface is located at one of the adjacent layer interfaces of the Si layer. .
The interface having the largest reflection coefficient is the interface between the Si layer and the air layer, and the interface having the largest reflection coefficient is the interface between the organic material layer and the Si layer. When the pointing vector is calculated, the result is as shown in FIG. The interface between the Si layer having a large pointing vector and the air layer is the main reflection interface in the present invention.
[0024]
The term "deformation" as used in the present invention refers to a deformation in which a given write-once optical recording medium constituent layer is simply deformed, and the deformation interface is clear.
For example, as in conventional CD-R and DVD-R, the interface between the substrate and the organic material layer is deformed, but the substrate and the organic material are melted or decomposed by recording, for example, the diffusion of the organic material into the substrate. Therefore, there is a high possibility that the two will mix near the interface, and the two will not have a clear interface. This obscuration of the deformed interface tends to cause a decrease in the recording contrast (modulation degree).
Therefore, in the present invention, the deformed interface is clearly maintained.
For this purpose, it is preferable that a layer that is deformed (a deformed layer or a recording layer in the present invention) is not mixed with an adjacent layer by recording.
The deformation of the deformable layer (the deformable layer or the recording layer in the present invention) is caused by the heat generated by the light absorbing layer provided separately from the deformable layer, but the deformable layer itself has a light absorbing function. Alternatively, the heat may be generated by the deformed layer itself.
[0025]
In the present invention, for example, a write-once optical recording medium provided with an organic material layer adjacent to a recording layer having both a light absorbing function for laser light and a deformation function of causing deformation without being melted or decomposed by irradiation of laser light I will provide a.
One of the reasons for providing the organic material adjacent to the recording layer is that the organic material layer can have a function of controlling the amount of deformation of the deformable layer.
This is, for example, in a write-once optical recording medium provided with a recording layer having both a light absorbing function for laser light on a substrate and a deformation function of causing deformation without being melted or decomposed by irradiation of laser light, the recording layer is deformed. This is because not only deformation due to the light absorbing function of the recording layer itself but also expansion of the substrate due to heat generated in the recording layer is greatly affected.
[0026]
Therefore, by providing an organic material layer between the substrate and a recording layer having both a light absorbing function for laser light and a deformation function of causing deformation without being melted or decomposed by the irradiation of the laser light, the recording layer is positioned on the side opposite to the substrate. In the case of a write-once optical recording medium that is deformed (to the side opposite to the substrate when viewed from the recording layer), the effect of the substrate deformation on the deformation of the recording layer toward the side opposite to the substrate can be reduced. Is the main reflection interface, and the deformation characteristics of the deformation layer such as the recording layer are the most important.)
Alternatively, by providing an organic material layer between a substrate and a recording layer having both a light absorbing function for laser light and a deformation function of causing deformation without being melted or decomposed by laser light irradiation, the recording layer is moved to the substrate side. In the case of a write-once optical recording medium that is deformed, the influence of substrate deformation that hinders the deformation of the recording layer toward the substrate can be reduced, and good deformation can be caused (in the present invention, the recording layer and the like can be formed). Is the main reflection interface, and the deformation characteristics of the deformation layer such as the recording layer are the most important.)
[0027]
In addition, the organic material layer has a function of improving the recording / reproducing characteristics by causing the organic material to be decomposed or deteriorated by heat from a layer having a light absorbing function such as a recording layer and changing its optical constant. It is possible to have.
The change in the optical constant referred to here means a decrease or increase in the real part of the complex refractive index, a decrease or increase in the imaginary part of the complex refractive index, a decrease or increase in the thickness of the organic material layer, or a combination thereof.
In addition, the recording / reproducing characteristics referred to here refer to the reflectance, jitter, modulation degree, tracking characteristics, etc., when recording is not performed.
Furthermore, the organic material layer should have a function to supplement the light absorbing function of the light absorbing layer or the recording layer having both the light absorbing function for laser light and the deformation function of causing deformation without being melted or decomposed by laser light irradiation. Is also possible.
[0028]
As a material used for the organic material layer, for example, a dye is preferable.
Dyes include polymethine, naphthalocyanine, phthalocyanine, squarylium, croconium, pyrylium, naphthoquinone, anthraquinone (indanthrene), xanthene, triphenylmethane, azulene, tetrahydrocholine, phenanthrene And triphenothiazine dyes, and metal complex compounds.
The formation of the dye layer can be performed by ordinary means such as vapor deposition, sputtering, CVD, and solvent application. In the case of using a coating method, the above-mentioned coloring matter or the like may be dissolved in an organic solvent and applied by a conventional coating method such as spraying, roller coating, dipping, or spin coating.
[0029]
Examples of the organic solvent used include alcohols such as methanol, ethanol and isopropanol; ketones such as acetone, methyl ethyl ketone and cyclohexanone; amides such as N, N-dimethylacetamide and N, N-dimethylformamide; sulfoxides such as dimethylsulfoxide. Ethers such as tetrahydrofuran, dioxane, diethyl ether and ethylene glycol monomethyl ether; esters such as methyl acetate and ethyl acetate; aliphatic halogenated carbons such as chloroform, methylene chloride, dichloroethane, carbon tetrachloride, and trichloroethane; Aromatics such as benzene, xylene, monochlorobenzene and dichlorobenzene; cellosolves such as methoxyethanol and ethoxyethanol; hexane, pentane, Cyclohexane, and hydrocarbons such as methylcyclohexane.
The thickness of the dye layer is suitably from 100 to 10 μm, preferably from 100 to 2000 °.
Note that a polymer can be used as the organic material layer.
[0030]
The deformable layer used in the present invention is not limited as long as it is deformed by recording.
However, in the present invention, it is preferable to use a material having a large difference in the complex refractive index from the adjacent layer, because the interface between the deformed layer and the adjacent layer is the main reflection interface.
Therefore, in general, a metal (for example, Au, Ag, Al, Cr, Ni, Fe, Sn, or the like) having a small refractive index (complex refractive index real part) or a metal having a small refractive index (complex refractive index real part) is used. Large materials [materials containing Si and / or Ge (eg, Si, Ge, Si _x Ge _1-x , Mg ₂ Ge, Mg ₂ Si, SiC, etc.); metals such as Nb, Ta, Be, V, or metal oxides thereof (eg, Ta) ₂ O ₅ , Nb ₂ O ₅ Etc.)]; AlSb, Al _x Ga _1-x As, CdSe, GaSb, Hg _1-x Cd _x Semiconductors such as Te, Se, Te, ZnTe, ZnS, PbS, InP, and GaP can be used.
[0031]
When the adjacent layer of the deformation layer forming the main reflection interface with the deformation layer has a relatively low refractive index (about 1.8 or less), for example, Al ₂ O ₃ , MgO, BeO, ZrO ₂ , UO ₂ , ThO ₂ Oxides such as simple oxides; SiO ₂ , 2MgO ・ SiO ₂ , MgO / SiO ₂ , CaO ・ SiO ₂ , ZrO ₂ ・ SiO ₂ , 3Al ₂ O ₃ ・ 2SiO ₂ 2MgO.2Al ₂ O ₃ ・ 5SiO ₂ , Li ₂ O ・ Al ₂ O ₃ ・ 4SiO ₂ Silicate-based oxides such as Al; ₂ TiO ₅ , MgAl ₂ O ₄ , Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ , BaTiO ₃ , LiNbO ₃ , PZT, PLZT (PbTiO ₃ -PbZrO ₃ Oxides), oxides of multiple oxides such as ferrite; Si ₃ N ₄ , Si _6-Z Al _Z O _Z N _8-Z , AlN, BN, TiN and other nitride-based non-oxides; SiC, B ₄ Carbide-based non-oxide such as C, TiC, WC; LaB ₆ , TiB ₂ , ZrB ₂ Boride-based non-oxides such as CdS, MoS ₂ Sulfide-based non-oxide such as MoSi ₂ For example, silicide-based non-oxides such as amorphous carbon, graphite, diamond, and the like, and their contents can be used.
[0032]
The light absorbing layer is not limited as long as it has a material having a relatively large absorption coefficient with respect to the recording wavelength (the absorption coefficient is an imaginary part of the complex refractive index; for example, preferably 0.2 or more). , Si and / or Ge containing materials (eg Si, Ge, Si _x Ge _1-x , Mg ₂ Ge, Mg ₂ Si, SiC, etc.); metals such as Nb, Ta, Be, V, or metal oxides thereof (eg, Ta) ₂ O ₅ , Nb ₂ O ₅ Etc.); AlSb, Al _x Ga _1-x As, CdSe, GaSb, Hg _1-x Cd _x Semiconductors such as Te, Se, Te, ZnTe, ZnS, PbS, InP, and GaP; metals such as Ni, Cr, Ti, Ta, and Fe having lower thermal conductivity than Ag and the like; Cu / Al, Ni / Fe, and the like Alloy or the like can be used.
It is also possible to use the above-mentioned dye as a material used for the organic material layer.
[0033]
As a recording layer having both a light absorbing function for laser light and a deformation function of causing deformation without being melted or decomposed by laser light irradiation, a material containing Si and / or Ge (for example, Si, Ge, Si _x Ge _1-x , Mg ₂ Ge, Mg ₂ Si, SiC, etc.); metals such as Nb, Ta, Be, V, or metal oxides thereof (eg, Ta) ₂ O ₅ , Nb ₂ O ₅ Etc.); AlSb, Al _x Ga _1-x As, CdSe, GaSb, Hg _1-x Cd _x Semiconductors such as Te, Se, Te, ZnTe, ZnS, PbS, InP, and GaP; metals such as Ni, Cr, Ti, Ta, and Fe having lower thermal conductivity than Ag; Cu / Al, Ni / Fe And the like can be used.
[0034]
The present invention can provide a "write-once optical recording medium having a simple layer structure and being inexpensive to manufacture" because it uses the simplest recording principle of deformation.
The reason that `` the write-once optical recording medium having no significant limitation on the recording / reproducing wavelength and the wavelength dependence of the recording characteristics is small '' can be provided, for example, a light absorption function for laser light, without melting or decomposing by irradiation of laser light. When a recording layer having a deforming function that causes deformation is used, as a material of such a recording layer, Si and / or Ge-containing materials such as SiC, Si, and Ge are preferably used. This is because they do not have such a large wavelength dependence as the organic materials used in conventional write-once optical recording media.
Therefore, the write-once optical recording medium of the present invention can easily record even light in the blue laser wavelength region of about 350 to 500 nm, and in principle, can record even light having a shorter wavelength.
[0035]
The reason that the "write-once optical recording medium with a relatively high reflectivity" can be provided is a light absorbing layer, a deformable layer, or a light absorbing function for laser light, and deformation without melting or decomposing by laser light irradiation. Si and / or Ge-containing materials such as SiC, Si, and Ge are preferably used for the recording layer having the function of causing deformation, because these materials have a large complex refractive index in a blue laser wavelength region or less. A recording layer having both a light absorbing layer, a deformable layer, or a light absorbing function for laser light and a deforming function of causing deformation without being melted or decomposed by laser light irradiation, and a reflection coefficient at an interface between these recording layers and the adjacent layer is increased. Is).
The reason for providing a “writable optical recording medium capable of achieving surface recording or recording with a high NA lens and achieving high density” can be provided because of the configuration of the recording medium of the present invention and the recording principle, the recording / reproducing direction is limited. This is because there is no layer structure (in addition to the recording / reproducing direction, a layer structure corresponding to the direction can be easily realized).
[0036]
Embodiments of the present invention are as shown in FIGS. The arrows in the drawing indicate the incident direction of the recording / reproducing light.
FIG. 34 shows an example in which a light absorption layer and a deformation layer are sequentially stacked on a substrate.
FIG. 35 is a recording example (modification example) of the write-once optical recording medium of FIG. 34 in which the interface between the deformation layer and an adjacent layer on the side opposite to the light absorption layer side of the deformation layer is a main reflection interface. ), Wherein the deformable layer is deformed in the direction of incidence of the laser beam by the heat generation of the light absorbing layer.
At this time, at the interface between the deformable layer and the light absorbing layer, a refractive index lowering portion or void due to volume expansion of the deformable layer material, a void due to separation of the deformable layer and the light absorbing layer, or a void or refraction due to a volume change of the light absorbing layer. A rate reduction portion and the like are formed.
In the present invention, the void can be considered to correspond to the refractive index lowering portion.
[0037]
FIG. 36 shows a recording example (modification) of the write-once optical recording medium of FIG. 34 in which the interface between the deformable layer and the light absorbing layer is a main reflection interface. Thereby, the deformable layer is deformed in the direction of incidence of the laser beam.
At this time, at the interface between the deformable layer and the layer on the side opposite to the light absorbing layer (opposite layer), the refractive index lowering portion or void due to the volume expansion of the deformable layer material, the void due to separation of the deformable layer and the opposite layer, A void, a refractive index lowering portion, and the like due to a change in volume of the opposite layer are formed.
[0038]
FIG. 37 shows an example in which a deformation layer and a light absorption layer are sequentially stacked on a substrate.
FIG. 38 shows a recording example (modification) of the write-once optical recording medium of FIG. 37 in which the interface between the deformable layer and the light absorbing layer is a main reflection interface. Thereby, the deformable layer is deformed in the direction of incidence of the laser beam.
At this time, at the interface between the deformable layer and the substrate, there are formed a refractive index lowering portion and a void due to the volume expansion of the deformable layer material, a void due to the separation of the deformable layer and the substrate, or a void and a lower refractive index portion due to the change in the volume of the substrate. Is done.
Although FIG. 38 illustrates that the interface of the adjacent layer of the light absorbing layer on the opposite side to the deformable layer is also deformed by the deformation of the deformable layer, this interface may not be deformed.
[0039]
FIG. 39 shows a recording example (modification) of the write-once optical recording medium of FIG. 37 in which the interface between the deformable layer and the substrate is a main reflection interface. The layer is deformed in the direction of incidence of the laser beam.
At this time, at the interface between the deformable layer and the light absorbing layer, a refractive index lowering portion or a gap due to volume expansion of the deformable layer material, a gap due to separation of the deformable layer and the light absorbing layer, or a gap or refraction due to a volume change of the light absorbing layer. A rate reduction portion and the like are formed.
[0040]
FIG. 40 illustrates an example in which a recording layer having both a light absorbing function for laser light and a deformation function of causing deformation without being melted or decomposed by laser light irradiation is stacked over a substrate.
FIG. 41 shows a recording example (modification) of the write-once optical recording medium of FIG. 40 in which the interface between the recording layer and an adjacent layer of the recording layer opposite to the substrate is a main reflection interface. This shows that the recording layer itself is deformed in the direction of incidence of the laser beam by the heat generation of the recording layer.
At this time, at the interface between the recording layer and the substrate, there are formed a refractive index-reduced portion or void due to volume expansion of the recording layer material, a void due to the separation of the recording layer and the substrate, or a void or refractive index reduced portion due to a change in the volume of the substrate. Is done.
[0041]
FIG. 42 shows a recording example (modification) of the write-once optical recording medium of FIG. 40 in which the interface between the recording layer and the substrate is a main reflection interface. It deforms itself in the direction of incidence of the laser beam.
At this time, at the interface between the recording layer and the layer on the side opposite to the substrate (opposite layer), a refractive index-reduced portion or void due to volume expansion of the recording layer material, a void due to separation of the recording layer from the opposite layer, or an opposite layer A void, a refractive index lowering portion, and the like are formed due to the change in volume.
[0042]
FIG. 43 shows an example in which an organic material layer and a recording layer having a function of absorbing laser light and a function of deforming without being melted or decomposed by laser light irradiation are sequentially stacked on a substrate.
FIG. 44 shows a write-once optical recording medium of FIG. 43 in which the interface between the recording layer and an adjacent layer on the side opposite to the organic material layer side of the recording layer is a main reflection interface (modification example). The recording layer is deformed in the direction of incidence of the laser beam by the heat generated by the recording layer.
At this time, at the interface between the recording layer and the organic material layer, there is a gap or a refraction due to the volume expansion of the recording layer material, a gap due to separation of the recording layer and the organic material layer, or a gap or refraction due to a volume change of the organic material layer. A rate reduction portion and the like are formed.
[0043]
FIG. 45 shows a recording example (modification) of the write-once optical recording medium of FIG. 43 in which the interface between the recording layer and the organic material layer is a main reflection interface. The recording layer is deformed in the direction of incidence of the laser beam.
At this time, at the interface between the recording layer and the layer on the side opposite to the organic material layer (opposite layer), a refractive index-reduced portion or a gap due to volume expansion of the recording layer material, a gap due to separation of the recording layer and the opposite layer, or A void, a refractive index lowering portion, and the like due to a change in volume of the opposite layer are formed.
Note that in FIGS. 44 to 45, the organic material layer in the portion where the recording layer is deformed may have a change in optical constant.
FIGS. 34 to 45 described above are examples of the minimum layer configuration in which the present invention is effective. In fact, in addition to the layer configurations of FIGS. A layer, a protective layer, an adhesive layer, a cover layer, and the like may be provided.
[0044]
【Example】
Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In FIGS. 1 (a) to 8 (a) and FIGS. 26 (a) to 31 (a), Unrec is a reproduction signal (RF level) at the time of no recording, and Top is a signal at the time of recording a mark row. The maximum reproduction signal level (that is, the space portion), Bottom is the minimum reproduction signal level when a mark string is recorded, and MA is the modulation degree calculated by (Top-Bottom) / Top.
First, Reference Examples 1 to 8 show that the conventional recording / reproducing method has a high possibility that a random pattern cannot be recorded / reproduced on an optical recording medium mainly based on a recording principle based on deformation.
[0045]
Reference Example 1
An optical recording medium having a 10 nm-thick SiC (light absorbing layer) provided on a polycarbonate substrate having a guide groove with a groove depth of 55 nm was manufactured.
The optical recording medium was irradiated with a 5.0 mW laser beam from the substrate side using a DDU-1000 (wavelength: 405 nm, NA: 0.65) optical disk evaluation device manufactured by Pulstec Industrial to produce grooves. 3T to 14T marks were independently recorded at the recording frequency of 65.4 MHz and the recording linear velocity of 6.0 m / sec in the portion (the groove position on the near side when viewed from the incident laser beam side).
At this time, FIG. 1A shows the result of measuring the dependence of the reproduction signal (RF level) on the recording mark length (Mark Length).
From the results of FIG. 1A, it can be confirmed that High to Low recording may be performed regardless of the recording mark length.
FIG. 1B shows the reproduction signal when the 3T mark is continuously recorded and the reproduction signal when the 4T mark is continuously recorded and the reproduction signal level when it is not recorded in FIG. ) Shows the reproduced signal level when the 6T mark is continuously recorded, the reproduced signal when the 8T mark is continuously recorded, and the reproduced signal level when the recording is not performed, and FIG. , A reproduction signal when a 14T mark is continuously recorded, and a reproduction signal level when no recording is performed.
From these results, it can be seen that all of the 3T, 4T, 6T, 8T, and 14T show a reproduction signal waveform that allows mark length recording.
[0046]
Reference Example 2
The same experiment as in Reference Example 1 was performed except that the recording power was set to 6.0 mW.
FIG. 2A shows the result of measuring the dependence of the reproduction signal (RF level) on the recording mark length (Mark Length).
From the result of FIG. 2A, a signal in which the recording polarity changes depending on the recording mark length, that is, a short mark is High to Low recording, but a long mark is a signal in which High to Low recording and Low to High recording are mixed. As a result, it is found that recording of the mark length becomes difficult.
FIG. 2B shows the reproduction signal when the 3T mark is continuously recorded and the reproduction signal when the 4T mark is continuously recorded and the reproduction signal level when it is not recorded in FIG. ) Shows the reproduction signal when the 6T mark is recorded continuously, the reproduction signal when the 8T mark is recorded continuously, and the reproduction signal level when the recording is not performed, and FIG. , A reproduction signal when a 14T mark is continuously recorded, and a reproduction signal level when no recording is performed.
From these results, 3T and 4T indicate reproduction signal waveforms that allow recording of mark length, while 6T, 8T, and 14T indicate reproduction signal waveforms in which the RF level at the center of the mark has greatly increased. The period of the reproduced signal looks twice as long as the original reproduced signal. This is well understood in comparison with FIG. 1 (c)]. It can be seen that mark length recording becomes difficult.
[0047]
Reference Example 3
An experiment was performed in exactly the same manner as in Reference Example 1 except that a laser beam of 6.0 mW was irradiated and recording was performed on a land portion (groove position on the back side as viewed from the incident laser beam side).
FIG. 3A shows the result of measuring the dependence of the reproduction signal (RF level) on the recording mark length (Mark Length).
From the result of FIG. 3A, it can be seen that the recording polarity changes according to the recording mark length, that is, high-to-low recording is performed for a short mark, but high-to-low recording and slightly low-to-high recording are mixed for a long mark. Such a signal tends to be generated, indicating that there is a possibility that the mark length recording becomes difficult.
FIG. 3B shows the reproduction signal when the 3T mark is continuously recorded and the reproduction signal when the 4T mark is continuously recorded and the reproduction signal level when it is not recorded in FIG. 3) shows the reproduction signal when the 6T mark is continuously recorded, the reproduction signal when the 8T mark is continuously recorded, and the reproduction signal level when the recording is not performed, and FIG. , A reproduction signal when a 14T mark is continuously recorded, and a reproduction signal level when no recording is performed.
From these results, 3T, 4T, 6T, and 8T indicate reproduction signal waveforms that allow recording of mark length, but 14T indicate reproduction signal waveforms in which the RF level at the center of the mark has greatly increased, making it difficult to record mark length. It turns out that it becomes.
[0048]
Reference example 4
The same experiment as in Reference Example 1 was performed except that a 7.0 mW laser beam was irradiated and recording was performed on a land portion (a groove position on the back side when viewed from the incident laser beam side).
FIG. 4A shows the result of measuring the dependence of the reproduction signal (RF level) on the recording mark length (Mark Length).
From the result of FIG. 4A, a signal in which the recording polarity changes depending on the recording mark length, that is, a short mark is High to Low recording, but a long mark is a signal in which High to Low recording and Low to High recording are mixed. As a result, it is found that recording of the mark length becomes difficult.
FIG. 4B shows the reproduction signal when the 3T mark is continuously recorded and the reproduction signal when the 4T mark is continuously recorded and the reproduction signal level when the recording is not performed. 4) shows the reproduction signal level when the 6T mark is continuously recorded, the reproduction signal level when the 8T mark is continuously recorded, and the reproduction signal level when the recording is not performed. FIG. , A reproduction signal when a 14T mark is continuously recorded, and a reproduction signal level when no recording is performed.
From these results, 3T and 4T indicate reproduction signal waveforms that allow recording of mark length, while 6T, 8T, and 14T indicate reproduction signal waveforms in which the RF level at the center of the mark has greatly increased. Appears twice as long as the original reproduced signal. This is well understood in comparison with FIG. 1 (c)]. It can be seen that mark length recording becomes difficult.
[0049]
Reference example 5
An optical recording medium in which a 20-nm-thick Si (light-absorbing layer) was provided on a polycarbonate substrate having a guide groove with a groove depth of 55 nm was prepared.
The optical recording medium was irradiated with a 5.0 mW laser beam from the substrate side using a DDU-1000 (wavelength: 405 nm, NA: 0.65) optical disk evaluation device manufactured by Pulstec Industrial to produce grooves. 3T to 14T marks were independently recorded at the recording frequency of 65.4 MHz and the recording linear velocity of 6.0 m / sec in the portion (the groove position on the near side when viewed from the incident laser beam side).
At this time, FIG. 5A shows the result of measuring the dependency of the reproduction signal (RF level) on the recording mark length (Mark Length).
FIG. 5B shows the reproduction signal when the 3T mark is continuously recorded and the reproduction signal when the 4T mark is continuously recorded and the reproduction signal level when it is not recorded in FIG. ) Shows the reproduced signal level when the 6T mark is recorded continuously, the reproduced signal when the 8T mark is recorded continuously, and the reproduced signal level when not recorded. FIG. 5D shows the 3T mark. , A reproduction signal when a 14T mark is continuously recorded, and a reproduction signal level when no recording is performed.
From these results, except for the 3T mark, low-to-high recording is obtained irrespective of the recording mark length, the polarity compatibility with the conventional one is lost, and high-to-low recording is caused by a change in the complex refractive index of the organic material layer. It can be confirmed that it cannot be used together with the recording principle (for example, increase of the absorption coefficient).
[0050]
Reference Example 6
The same experiment as in Reference Example 5 was performed except that the recording power was changed to 6.0 mW.
FIG. 6A shows the result of measuring the dependence of the reproduction signal (RF level) on the recording mark length (Mark Length).
FIG. 6B shows the reproduction signal when the 3T mark is continuously recorded and the reproduction signal when the 4T mark is continuously recorded and the reproduction signal level when the recording is not performed. ) Shows the reproduction signal when the 6T mark is continuously recorded, the reproduction signal when the 8T mark is continuously recorded, and the reproduction signal level when not recorded, and FIG. 6D shows the 3T mark. , A reproduction signal when a 14T mark is continuously recorded, and a reproduction signal level when no recording is performed.
From these results, except for the 3T mark, low-to-high recording is obtained irrespective of the recording mark length, the polarity compatibility with the conventional one is lost, and high-to-low recording is caused by a change in the complex refractive index of the organic material layer. It can be confirmed that it cannot be used together with the recording principle (for example, increase of the absorption coefficient).
[0051]
Reference Example 7
An experiment was performed in exactly the same manner as in Reference Example 5, except that a laser beam of 5.0 mW was irradiated and recording was performed on a land portion (groove position on the back side when viewed from the incident laser beam side).
FIG. 7A shows the result of measuring the dependence of the reproduction signal (RF level) on the recording mark length (Mark Length).
FIG. 7B shows the reproduction signal when the 3T mark is continuously recorded and the reproduction signal when the 4T mark is continuously recorded and the reproduction signal level when it is not recorded in FIG. 7) shows the reproduction signal when the 6T mark is continuously recorded, the reproduction signal when the 8T mark is continuously recorded, and the reproduction signal level when the recording is not performed, and FIG. , A reproduction signal when a 14T mark is continuously recorded, and a reproduction signal level when no recording is performed.
From these results, except for the 3T mark, low-to-high recording is obtained irrespective of the recording mark length, the polarity compatibility with the conventional one is lost, and high-to-low recording is caused by a change in the complex refractive index of the organic material layer. It can be confirmed that it cannot be used together with the recording principle (for example, increase of the absorption coefficient).
[0052]
Reference Example 8
An experiment was performed in exactly the same manner as in Reference Example 5, except that a laser beam of 6.0 mW was irradiated and recording was performed on a land portion (groove position on the back side when viewed from the incident laser beam side).
FIG. 8A shows the result of measuring the dependence of the reproduction signal (RF level) on the recording mark length (Mark Length).
FIG. 8B shows the reproduction signal when the 3T mark is continuously recorded and the reproduction signal when the 4T mark is continuously recorded and the reproduction signal level when it is not recorded in FIG. 8) shows the reproduction signal when the 6T mark is continuously recorded, the reproduction signal when the 8T mark is continuously recorded, and the reproduction signal level when the recording is not performed. FIG. , A reproduction signal when a 14T mark is continuously recorded, and a reproduction signal level when no recording is performed.
From these results, except for the 3T mark, low-to-high recording is obtained irrespective of the recording mark length, the polarity compatibility with the conventional one is lost, and high-to-low recording is caused by a change in the complex refractive index of the organic material layer. It can be confirmed that it cannot be used together with the recording principle (for example, increase of the absorption coefficient).
[0053]
As described above, from the results of Reference Examples 1 to 8, it is difficult to perform recording / reproducing by the mark length in the conventional method of recording / reproducing from the substrate side with a simple layer configuration in which the light absorbing layer is provided on the substrate. It was confirmed that the recording polarity was often changed from Low to High.
[0054]
Next, in Example 1, even under a simple layer configuration in which a light absorbing layer is provided on a substrate, recording / reproducing can be performed by the mark length, and conditions under which the recording polarity becomes High to Low will be examined. .
[0055]
Example 1
A recording mark having a mark length of about 3T (0.7λ) and about 8T (2.0λ) with a layer structure of substrate / light absorbing layer Si (thickness: 20 nm) (however, the width of the 3T mark is 0.7λ, When the width of the 8T mark is 0.8λ and the size of the mark in the height direction is 0.125λ), when the recording position, the recording mark deformation direction, and the reproducing direction are changed as shown below, It was calculated whether such a reproduced signal could be obtained.
・ Recording position: Land or Groove
・ Record mark deformation direction: Bump or Pit
-Reproduction direction: From the substrate side = [From Sub] or from the opposite substrate side = [From Air]
In calculation, here, Pit indicates a recording mark deformed in the opposite direction to the laser light incident direction, and Bump indicates a recording mark deformed in the laser light incident direction (see FIG. 9). The substrate groove shape was (A, B, C, D, ζ) = (0.2λ, 0.8λ, 1.0λ, 1.8525λ, 0.1375λ).
[0056]
The calculation results are as shown in FIGS. 10 to 17. FIG. 10 shows the result when the recording portion having the pit formed on the land is reproduced from the substrate side, and FIG. 11 shows the recording when the bump was formed on the land. FIG. 12 shows a result of reproducing a recording portion in which Pit is formed in the groove portion from the substrate side, and FIG. 13 shows a recording portion in which Bump is formed in the groove portion. FIG. 14 shows a case where a recording portion having a pit formed on a land portion is reproduced from the Si side, and FIG. 15 shows a case where a recording portion having a bump formed on the land portion is reproduced from the Si side. As a result, FIG. 16 shows the result when the recording portion in which the Pit is formed in the groove portion is reproduced from the Si side, and FIG. 17 shows the result when the recording portion in which the Bump is formed in the groove portion is reproduced from the Si side. .
10 to 17, the horizontal axis indicates the position of the reproduction laser beam, and the vertical axis indicates the level of the reproduction signal (the reproduction reflected light is detected by the four-split element, while the vertical axis is the sum signal of the four-split element [ Sum Signal]).
[0057]
From this result, it is generally considered that Pit is formed when recording is performed from the substrate, and Bump is formed when recording is performed from the air layer side. Therefore, the Bump condition (see FIG. 11 and FIG. 13) and the calculation results under the Pit conditions (FIGS. 14 and 16) in recording and reproduction from the air layer side are considered as unusual, and in recording and reproduction from the substrate side, the recording polarity depends on the recording position. However, it can be seen that the recording polarity is constant (High to Low) in recording and reproduction from the air layer side. Similarly, if the calculation results under the Bump conditions for recording / reproducing from the substrate and the Pit conditions for recording / reproducing from the air layer side are excluded as being unusual, the recording / reproducing from the substrate side will have a land It was found that a differential waveform was generated in recording in the section (see FIG. 10).
[0058]
The calculation result of the first embodiment describes, for example, the phenomena shown in FIGS. 5 to 8 (in actual measurement, phenomena in which low-to-high and differential waveforms occur not only in the land but also in the groove). Can not.
Therefore, as a result of intensive studies, the observation of a reproduced signal waveform in which the RF level rises at the center of the recording mark is due to a decrease in the refractive index such as a void generated inside the light absorption layer of SiC or Si. Alternatively, it was considered that the cause was caused by a gap generated between the light absorbing layer of SiC or Si and the substrate, or a refractive index reduced portion such as a gap generated in an expanded portion of the substrate. Even in the case of low-to-high recording, short marks often have high-to-low recording. Therefore, it is considered that the short mark has a greater effect of the diffraction effect than the interference effect.
[0059]
Accordingly, most of the reflected light is reflected light at the deformed interface (main reflection interface), and a refractive index lowering portion such as a void is not located closer to the incident laser light than the main reflection interface. With such a configuration, it is considered that the influence of the interference effect of the deformed portion can be reduced and the effect of the diffraction effect due to the deformation can be increased.
By doing so, it was considered that most of the reflected light is produced even by a long mark due to a diffraction effect due to deformation, so that mark length recording is always possible and High to Low recording can be performed.
In order to realize the above idea, the present inventor, for example, in an optical recording medium provided with a light absorbing layer on the substrate, there is a possibility that a gap is generated between the substrate and the light absorbing layer It has been found that it is very effective to reproduce information from an optical recording medium from the light absorbing layer side.
[0060]
◎ Therefore, next, an optical recording medium having a light-absorbing layer provided on a substrate, in which a gap may be generated between the substrate and the light-absorbing layer, is reproduced from the light-absorbing layer side. Thus, it is clarified by simulation that mark length recording is possible and High to Low recording may be performed.
[0061]
Example 2
A recording mark having a mark length of about 8T (2.0λ) in a layer configuration of substrate / light absorbing layer SiC (thickness 10 nm) or substrate / light absorbing layer Si (thickness 20 nm) (however, the mark width is 0.8525λ, and the size of the mark in the height direction was 0.30λ), when the following recording position, the presence or absence of a gap, and the reproduction direction were changed, what kind of reproduction signal was It was calculated whether it could be obtained.
・ Recording position: Land or Groove
・ With or without air gap: [No Bubble] or [Bubble]
-Reproduction direction: From the substrate side = [From Sub] or from the opposite substrate side = [From Air]
The substrate groove shape is (A, B, C, D, ζ) = (0.2λ, 1.0525λ, 1.2525λ, 1.8525λ, 0.1375λ) in the case of reproduction from the substrate side. (A, B, C, D, ζ) = (0.2λ, 0.8λ, 1.0λ, 1.8525λ, 0.1375λ).
[0062]
The calculation results are as shown in FIGS. 18 to 25. FIGS. 18 to 21 show the results when Si is provided on the substrate, and FIGS. 22 to 25 show the results when SiC is provided on the substrate.
FIG. 18 shows the result when the recording portion having the pit formed in the land portion is reproduced from the substrate side, FIG. 19 shows the result when the recording portion having the pit formed in the groove portion is reproduced from the substrate side, and FIG. FIG. 21 shows a result of reproducing a recording portion having a bump formed in a groove portion from the Si side, FIG. 22 shows a result of reproducing a recording portion having a bump formed in a groove portion from the Si side, and FIG. FIG. 23 shows the result when the formed recording portion was reproduced from the substrate side, FIG. 23 shows the result when the recording portion having the Pit formed in the groove portion was reproduced from the substrate side, and FIG. 24 shows the recording when the Bump was formed in the land portion. FIG. 25 shows the result when the recording portion where the bump is formed in the groove portion is reproduced from the SiC side as a result when the portion is reproduced from the SiC side.
18 to 25, the horizontal axis indicates the position of the reproduction laser beam, and the vertical axis indicates the level of the reproduction signal (the reproduction reflection light is detected by the four-split element, and the vertical axis is the sum signal of the four-split element [ Sum Signal]).
[0063]
From the above simulation results, it was found that in order to generate a reproduced signal actually observed, it is necessary to generate a gap (a portion having a low refractive index) between the light absorbing layer of SiC or Si and the substrate. . In other words, it was confirmed that there is a possibility that a gap (a portion having a low refractive index) may be generated between the substrate and the light absorbing layer of SiC or Si in actual recording. In the second embodiment, the calculation is performed on the assumption that a gap is generated (peeled) between the light absorbing layer and the substrate. However, when a refractive index lowering portion such as a gap is generated inside the light absorbing layer, or Similar calculation results are obtained when a refractive index lowering portion such as a void occurs in the substrate. Therefore, it was confirmed that voids (refraction-reduced portions) may be generated between the light absorbing layer made of SiC or Si and the substrate, in the light absorbing layer, or in the substrate in actual recording.
Also, in the reproduction from the substrate side (FIGS. 18, 19, 22, and 23), it can be seen that the reproduced signal waveform greatly changes depending on the presence or absence of the gap, and if the gap exists, the recording polarity is changed from low to high and differentiated. Although waveform formation is likely to occur, in reproduction from the light absorbing layer side (FIGS. 20, 21, 24, and 25), the reproduced signal waveform does not change significantly due to the presence or absence of a gap, does not have a differential waveform, and has a recording polarity. It was found that a signal of High to Low was obtained.
[0064]
Based on the above simulation results, the following Examples 3 to 8 demonstrate that the optical recording medium of the present invention enables mark length recording and high-to-low recording.
[0065]
Example 3
An optical recording medium in which a 10 nm-thick SiC light absorbing layer was provided on a polycarbonate substrate having a guide groove with a groove depth of 55 nm was prepared.
The optical recording medium was irradiated with 8.0 mW of laser light from the SiC side using an optical disk evaluation device DDU-1000 (wavelength: 405 nm, NA: 0.65) manufactured by Pulstec Industrial. 3T to 14T marks were independently recorded at a recording frequency of 65.4 MHz and a recording linear velocity of 6.0 m / sec (at the groove position on the near side when viewed from the incident laser beam side).
At this time, FIG. 26A shows the result of measuring the dependence of the reproduction signal (RF level) on the recording mark length (Mark Length).
From the result of FIG. 26A, it can be confirmed that High to Low recording may be performed regardless of the recording mark length.
FIG. 26B shows a reproduction signal when the 3T mark is continuously recorded and a reproduction signal when the 4T mark is continuously recorded and a reproduction signal level when the recording is not performed, as shown in FIG. ) Shows the reproduction signal when the 6T mark is recorded continuously, the reproduction signal when the 8T mark is recorded continuously, and the reproduction signal level when it is not recorded, and FIG. 26 (d) shows the 3T mark. , A reproduction signal when a 14T mark is continuously recorded, and a reproduction signal level when no recording is performed.
From this result, it can be seen that 3T, 4T, 6T, 8T, and 14T all show a reproduction signal waveform that allows mark length recording.
[0066]
Example 4
The same experiment as in Example 3 was performed except that the recording power was set to 9.0 mW.
FIG. 27A shows the result of measuring the dependence of the reproduction signal (RF level) on the recording mark length (Mark Length).
From the results of FIG. 27A, it can be confirmed that High to Low recording may be performed regardless of the recording mark length.
FIG. 27B shows the reproduction signal when the 3T mark is continuously recorded and the reproduction signal when the 4T mark is continuously recorded and the reproduction signal level when the recording is not performed. ) Shows the reproduced signal level when the 6T mark is recorded continuously, the reproduced signal when the 8T mark is recorded continuously, and the reproduced signal level when not recorded. FIG. 27D shows the 3T mark. , A reproduction signal when a 14T mark is continuously recorded, and a reproduction signal level when no recording is performed.
From this result, it can be seen that 3T, 4T, 6T, 8T, and 14T all show a reproduction signal waveform that allows mark length recording.
[0067]
Example 5
The same experiment as in Example 3 was performed except that the laser light of 7.0 mW was applied and recording was performed in a groove portion (groove position on the back side when viewed from the incident laser light side).
FIG. 28A shows the result of measuring the dependence of the reproduction signal (RF level) on the recording mark length (Mark Length).
From the result of FIG. 28A, it can be confirmed that High to Low recording may be performed regardless of the recording mark length.
FIG. 28B shows a reproduction signal when the 3T mark is continuously recorded and a reproduction signal when the 4T mark is continuously recorded and a reproduction signal level when the recording is not performed. ) Shows the reproduced signal level when the 6T mark is continuously recorded, the reproduced signal when the 8T mark is continuously recorded, and the reproduced signal level when not recorded. FIG. 28 (d) shows the 3T mark. , A reproduction signal when the 14T mark is continuously recorded, and a reproduction signal level when no recording is performed.
From this result, it can be seen that 3T, 4T, 6T, 8T, and 14T all show a reproduction signal waveform that allows mark length recording.
[0068]
Example 6
The same experiment as in Example 3 was performed, except that a laser beam of 8.0 mW was irradiated, and recording was performed in a groove portion (groove position on the back side when viewed from the incident laser beam side).
FIG. 29A shows the result of measuring the dependence of the reproduction signal (RF level) on the recording mark length (Mark Length).
From the result of FIG. 29A, it can be confirmed that High to Low recording may be performed regardless of the recording mark length.
FIG. 29D shows a reproduced signal when a 3T mark is continuously recorded, a reproduced signal when a 14T mark is continuously recorded, and a reproduced signal level when not recorded.
From this result, it can be seen that both the shortest and longest marks show a reproduction signal waveform that allows recording of mark length.
[0069]
Example 7
An optical recording medium in which a 20-nm-thick Si (light-absorbing layer) was provided on a polycarbonate substrate having a guide groove with a groove depth of 55 nm was prepared.
The optical recording medium was irradiated with 6.0 mW of laser light from the Si side using a DDU-1000 (wavelength: 405 nm, NA: 0.65) optical disk evaluation device manufactured by Pulstec Industrial. 3T to 14T marks were independently recorded at a recording frequency of 65.4 MHz and a recording linear velocity of 6.0 m / sec (at the groove position on the near side when viewed from the incident laser beam side).
At this time, FIG. 30A shows the result of measuring the recording mark length (Mark Length) dependency of the reproduction signal (RF level).
From the result of FIG. 30A, it can be confirmed that High to Low recording may be performed regardless of the recording mark length.
FIG. 30B shows a reproduction signal when the 3T mark is continuously recorded and a reproduction signal when the 4T mark is continuously recorded and a reproduction signal level when the recording is not performed. ) Shows the reproduction signal when the 6T mark is continuously recorded, the reproduction signal when the 8T mark is continuously recorded, and the reproduction signal level when the recording is not performed, and FIG. , A reproduction signal when the 14T mark is continuously recorded, and a reproduction signal level when no recording is performed.
From this result, it can be seen that 3T, 4T, 6T, 8T, and 14T all show a reproduction signal waveform that allows mark length recording.
[0070]
Example 8
The same experiment as in Example 7 was performed except that the recording power was set to 7.0 mW.
FIG. 31A shows the result of measuring the dependence of the reproduction signal (RF level) on the recording mark length (Mark Length).
From the result of FIG. 31A, it can be confirmed that High to Low recording may be performed regardless of the recording mark length.
FIG. 31B shows the reproduction signal when the 3T mark is continuously recorded and the reproduction signal when the 4T mark is continuously recorded and the reproduction signal level when the recording is not performed, as shown in FIG. ) Shows the reproduced signal level when the 6T mark is recorded continuously, the reproduced signal when the 8T mark is recorded continuously, and the reproduced signal level when not recorded. FIG. 31 (d) shows the 3T mark. , A reproduction signal when a 14T mark is continuously recorded, and a reproduction signal level when no recording is performed.
From this result, it can be seen that 3T, 4T, 6T, 8T, and 14T all show a reproduction signal waveform that allows mark length recording.
[0071]
As described above, as shown in Examples 3 to 8, a simple optical recording medium in which a light absorbing layer is simply provided on a substrate, between the substrate and the light absorbing layer, or between the light absorbing layer itself and the substrate. It has been proved by an experiment that the mark length can be recorded and the high-to-low recording can be performed by reproducing from the light absorbing layer side with respect to the optical recording medium in which a void may be generated inside the recording medium. Was.
[0072]
* Finally, the characteristics of the write-once optical recording medium of the present invention are clarified by Examples 9 to 10.
[0073]
Example 9
On a polycarbonate substrate having a guide groove with a groove depth of 55 nm, a dye layer comprising a Co metal complex represented by the following [Chemical Formula 1] and [Chemical Formula 2] having a thickness of about 60 nm, and further having an SiC thickness of 10 nm provided thereon. A recording medium was manufactured.
The optical recording medium was irradiated with 9.0 mW laser light from the SiC side using an optical disk evaluation device DDU-1000 (wavelength: 405 nm, NA: 0.65) manufactured by Pulstec Industrial. A signal of 8-16 modulation was recorded at a recording frequency of 65.4 MHz and a recording linear velocity of 6.0 m / sec in the portion (groove position on the near side when viewed from the incident laser beam side).
As a result, the degree of modulation was about 70%, the recording polarity was High to Low, a very clear eye pattern as shown in FIG. 32 was obtained, and the jitter (σ / Tw) was 8.5%. Was.
[0074]
Embedded image

Embedded image

[0075]
Example 10
On a polycarbonate substrate having a guide groove having a groove depth of 55 nm, an optical recording medium was prepared in which the dye layer represented by the above [Chemical Formula 1] was provided with a thickness of about 40 nm and SiC was further provided thereon with a thickness of 10 nm.
The optical recording medium is irradiated with laser light from the SiC side using an optical disk evaluation device manufactured by Pulstec Industrial Co., Ltd., DDU-1000 (wavelength: 405 nm, NA: 0.65). At a recording position of 65.4 MHz and a recording linear velocity of 6.0 m / sec, an 8-16 modulation signal was recorded in a groove position on the near side as viewed from the light side by changing the recording power.
As a result, the recording polarity was High to Low, and good jitter and modulation as shown in FIG. 33 were obtained.
[0076]
【The invention's effect】
According to the inventions 1 to 14, a write-once optical recording medium having the following characteristics can be provided.
-It can be manufactured at low cost with a simple layer configuration.
-There is no great limitation on the recording / reproducing wavelength, and the wavelength dependence of the recording characteristics is small.
-A relatively high reflectance is obtained.
A write-once optical recording medium that performs recording and reproduction using deformation, but the recording polarity does not change depending on the recording mark length or recording power and is constant.
-Although it is a write-once optical recording medium that performs recording and reproduction using deformation, the reproduction waveform of the recording mark does not show a differential shape.
-Although it is a write-once optical recording medium that performs recording and reproduction using deformation, the recording polarity tends to be Highto Low recording.
-Surface recording or recording with a high NA lens can be performed, and high density can be achieved.
[Brief description of the drawings]
FIG. 1 is a diagram showing a recording result of Reference Example 1.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 2 is a diagram showing a recording result of Reference Example 2.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 3 is a view showing a recording result of Reference Example 3;
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 4 is a diagram showing a recording result of Reference Example 4.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 5 is a diagram showing a recording result of Reference Example 5.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 6 is a diagram showing a recording result of Reference Example 6.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 7 is a view showing a recording result of Reference Example 7;
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 8 is a view showing a recording result of Reference Example 8.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 9 is an explanatory diagram of groove parameters.
(A) A diagram for explaining a deformed recording mark (From Sub).
(B) A diagram for explaining a deformed recording mark (From Air).
FIG. 10 is a diagram illustrating a calculation result in a case where a recording unit in which a pit is formed on a land is reproduced from the substrate side according to the first embodiment.
FIG. 11 is a diagram showing a calculation result in a case where a recording portion having a bump formed in a land portion is reproduced from the substrate side in the first embodiment.
FIG. 12 is a diagram illustrating a calculation result in a case where a recording unit in which a Pit is formed in a groove portion is reproduced from the substrate side according to the first embodiment.
FIG. 13 is a diagram showing a calculation result in the case where the recording portion in which the bump is formed in the groove portion is reproduced from the substrate side in the first embodiment.
FIG. 14 is a diagram illustrating a calculation result in a case where a recording portion in which a Pit is formed in a land portion is reproduced from the Si side according to the first embodiment.
FIG. 15 is a diagram showing a calculation result in the case where a recording portion in which a bump is formed in a land portion is reproduced from the Si side in the first embodiment.
FIG. 16 is a diagram showing a calculation result in a case where a recording portion in which a Pit is formed in a groove portion is reproduced from the Si side according to the first embodiment.
FIG. 17 is a diagram showing a calculation result in the case where the recording portion in which the bump is formed in the groove portion is reproduced from the Si side in the first embodiment.
FIG. 18 is a diagram illustrating a calculation result in a case where Si is provided on a substrate and a recording portion having a Pit formed in a land portion is reproduced from the substrate side in the second embodiment.
FIG. 19 is a diagram illustrating a calculation result in the case where Si is provided on the substrate and the recording portion in which the Pit is formed in the groove portion is reproduced from the substrate side in the second embodiment.
FIG. 20 is a diagram illustrating a calculation result in the case where Si is provided on the substrate and the recording portion in which the bump is formed in the land portion is reproduced from the Si side in the second embodiment.
FIG. 21 is a diagram showing a calculation result in a case where Si is provided on a substrate and a recording portion in which a bump is formed in a groove portion is reproduced from the Si side in the second embodiment.
FIG. 22 is a diagram illustrating a calculation result in a case where SiC is provided on a substrate and a recording portion in which a Pit is formed in a land portion is reproduced from the substrate side in the second embodiment.
FIG. 23 is a diagram illustrating a calculation result in the case where SiC is provided on the substrate and the recording portion in which the Pit is formed in the groove portion is reproduced from the substrate side in Example 2;
FIG. 24 is a diagram illustrating a calculation result in a case where SiC is provided on a substrate and a recording portion in which a bump is formed in a land portion is reproduced from the SiC side in the second embodiment.
FIG. 25 is a diagram illustrating a calculation result in the case where SiC is provided on the substrate and the recording portion in which the bump is formed in the groove portion is reproduced from the SiC side in the second embodiment.
FIG. 26 is a diagram showing a recording result of Example 3.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 27 is a view showing a recording result of Example 4.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 28 is a view showing a recording result of Example 5.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 29 is a view showing a recording result of Example 6.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 30 is a view showing a recording result of Example 7.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 31 is a view showing a recording result of Example 8.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 32 is a diagram showing an eye pattern according to a ninth embodiment.
FIG. 33 is a diagram illustrating a jitter and a modulation factor according to the tenth embodiment.
FIG. 34 is a diagram showing an embodiment of the present invention having a light absorbing layer and a deformable layer on a substrate.
FIG. 35 is a recording example (modification example) of the write-once optical recording medium of FIG. 34, in which the interface between the deformation layer and an adjacent layer on the side opposite to the light absorption layer side of the deformation layer is a main reflection interface; FIG.
FIG. 36 is a diagram showing a recording example (modification) of the write-once optical recording medium of FIG. 34, in which the interface between the deformation layer and the light absorption layer is a main reflection interface.
FIG. 37 is a diagram showing an embodiment of the present invention having a deformation layer and a light absorption layer on a substrate.
FIG. 38 is a diagram showing a recording example (modification) of the write-once optical recording medium of FIG. 37 in which the interface between the deformation layer and the light absorption layer is a main reflection interface.
39 is a diagram showing a recording example (modification) of the write-once optical recording medium of FIG. 37, in which the interface between the deformation layer and the substrate is a main reflection interface.
FIG. 40 is a diagram showing an embodiment of the present invention having a recording layer on a substrate.
41 is a recording example (modification) of the write-once optical recording medium of FIG. 40, in which the interface between the recording layer and an adjacent layer of the recording layer opposite to the substrate is a main reflection interface. FIG.
FIG. 42 is a diagram showing a recording example (modification) of the write-once optical recording medium of FIG. 40 in which the interface between the recording layer and the substrate is a main reflection interface.
FIG. 43 is a diagram showing an embodiment of the present invention having an organic material layer and a recording layer on a substrate.
FIG. 44 is a recording example (modification) of the write-once optical recording medium of FIG. 40 in which the interface between the recording layer and an adjacent layer of the recording layer opposite to the organic material layer is a main reflection interface. FIG.
FIG. 45 is a diagram showing a recording example (modification) of the write-once optical recording medium of FIG. 40 in which the interface between the recording layer and the organic material layer is a main reflection interface.
FIG. 46 is a view showing a layer structure of a conventional disk.
FIG. 47 is a view for explaining a waveform of a reproduction signal when a recording mark of mark length recording is reproduced.
(A) General case
(B) Differential waveform with inflection points near the leading and trailing edges of the recording mark
(C) Differential waveform with inflection point near the center of the recording mark
FIG. 48 is a diagram showing a calculation result of a pointing vector in an optical recording medium in which an organic material layer and a Si layer are stacked on a substrate, and recording and reproduction are performed from the substrate side.
FIG. 49 is a diagram showing a calculation result of a pointing vector in an optical recording medium in which an organic material layer and a Si layer are laminated on a substrate, and recording and reproduction are performed from the Si layer side.
[Explanation of symbols]
Mark Length Mark length
T reference clock
RF Level (V) RF (reproduction signal) level (volt)
Modulated amplitude modulation degree
Unrec Reproduction signal (RF) level when not recording
Top Reproduced signal level when recording a mark sequence (that is, space part)
Bottom Minimum reproduction signal level when a mark sequence is recorded (that is, mark portion)
Modulation degree calculated by MA (Top-Bottom) / Top
Time 0.5 (μs / div) Time (1 memory 0.5 microsecond)
Sum Signal Sum signal (reproduction signal)
Beam Position (μm) Beam position (deviation of beam center from mark center (micrometer)
A Width from the reference point to the near end of the adjacent land or groove
B Width from reference point to far end of adjacent land or groove
C Width from the reference point to the near end of the next groove or land
D Width from reference point to far end of next groove or land
高 Height from groove bottom to land top
Pit Recording mark deformed in the opposite direction of the laser beam incidence
Bump Recording mark deformed in the direction of laser beam incidence
From Sub Substrate side
From Air from opposite side of substrate
σ / Tw jitter
Position in Z position layer direction (indicating the thickness of organic material layer and Si layer)
Y pointing vector (time average of pointing vector)

Claims (14)

At least a deformable layer and a light absorbing layer, and an interface between the deformable layer and an adjacent layer on the laser light incident side in contact with the deformable layer is used as a main reflection interface, and the light absorbing layer is deformed by heat generation of the light absorbing layer by irradiation with laser light. A write-once optical recording medium, wherein a recording mark is formed by deforming a layer in an incident direction of a laser beam. 2. The write-once optical recording medium according to claim 1, wherein the deformable layer and an adjacent layer on the laser beam incident side that is in contact with the deformable layer are not mixed by recording. In the vicinity of the interface between the deformed layer and the layer located on the back side of the deformed layer as viewed from the laser beam incident side, a reduced refractive index portion or a void portion of the material constituting the layer located on the back side is formed. The write-once optical recording medium according to claim 1, wherein a recording mark is formed. 3. The write-once optical recording medium according to claim 1, wherein a recording mark is formed by forming a refractive index lowering portion or a void portion of a material constituting the deforming layer in the deforming layer. 5. The write-once optical recording medium according to claim 1, wherein the light absorbing layer is made of an organic material. 5. The write-once optical recording medium according to claim 1, wherein the light absorbing layer contains Si and / or Ge. At least a recording layer, wherein the recording layer has both a function of absorbing laser light and a function of causing deformation without being melted or decomposed by irradiation with laser light. Medium. The recording layer has at least a recording layer, and the recording layer has both a light absorbing function for laser light and a deformation function of causing deformation without being melted or decomposed by irradiation of the laser light. The interface with the adjacent layer on the laser light incident side that is in contact with the main reflection interface is used as the main reflection interface, and the recording layer itself is deformed in the laser light incident direction due to heat generation of the recording layer by the irradiation of the laser light, thereby forming a recording mark. A write-once optical recording medium characterized by the above-mentioned. It has at least a recording layer and an organic material layer, and the recording layer has both a light absorbing function for laser light and a deformation function of causing deformation without being melted or decomposed by irradiation with laser light. Write-once optical recording medium. Having at least a recording layer and an organic material layer, the recording layer has both a light absorbing function for laser light and a deformation function of causing deformation without being melted or decomposed by irradiation of laser light, and the recording layer and The interface between the recording layer and the adjacent layer on the laser light incident side that is in contact with the recording layer is defined as a main reflection interface, and the recording layer itself is deformed in the laser light incident direction due to heat generation of the recording layer due to irradiation of the laser light, whereby the recording mark is formed. A write-once optical recording medium characterized by being formed. In the vicinity of the interface between the recording layer and the layer existing on the back side of the recording layer when viewed from the laser beam incident side, a reduced refractive index portion or a void portion of the material constituting the layer existing on the back side is formed. 11. The write-once optical recording medium according to claim 7, wherein a recording mark is formed. The write-once light according to any one of claims 7 to 10, wherein a recording mark is formed by forming a reduced refractive index portion or a void portion of a material forming the recording layer in the recording layer. recoding media. 13. The write-once optical recording medium according to claim 7, wherein the recording layer contains Si and / or Ge. 14. The write-once optical recording medium according to claim 1, wherein a recording mark can be formed by blue laser light having a wavelength of 350 to 500 nm.

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