JP2004047055A - Information recording medium and its analyzing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a write-once optical recording medium made of organic materials even in a blue laser wavelength range, especially in a wavelength range of around 405 (nm), a write-once optical recording medium with large modulation, and a write-once optical recording medium having little change in recording characteristics, such as recording sensitivity and modulation, and jitter and an error rate, and reflectance or the like with respect to the fluctuations of a recording and reproduction wavelength. <P>SOLUTION: This information recording medium has a layer structure, wherein a heat receiving layer containing dye materials is laminated on a light receiving layer so as to make the film thickness ≤200 nm. Light showing a gaussian distribution is emitted to the medium to perform recording. Consequently, in the heat receiving layer, Inner and outer parts of record mark regions where light intensity is increased for recording change in quality to thereby perform recording. <P>COPYRIGHT: (C)2004,JPO

Description

【００３９】
【数２】

また、エネルギー反射率Ｒは、振幅反射率γを用いて下記式で表わされる。
【００４０】
【数３】
Ｒ＝｜γ｜２　　　　　　　　　………（３）
すなわち、入射波をａ０ｃｏｓθとして、反射した波の合成波をａ’ｃｏｓ（θ＋Δ）とするとき、エネルギー反射率Ｒは下記式によって表わされる。
【００４１】
【数４】

このことを利用して、各要因の好適となる範囲や材料の選定、記録条件を算出することができる。
【００４２】
熱受容層（４）は膜厚が５ｎｍより薄い場合は熱の吸収が充分ではなく、変形や変化が不充分となる。また、膜厚が２００ｎｍより厚い場合は体積が大きいため変形が抑えられたり、熱的な影響を受けて光学的に変化できない部分が存在するため問題である。
本発明において、熱受容層は、前述した材料を有機溶媒に溶解した後、これを光吸収層上にスピンコーティングすることによって形成される。この際、有機溶媒は、前述した材料が容易に溶解できるものである必要があり、その溶液は光吸収層にポアを有する場合はポアに進入しない一定の接触角を有する必要がある。
【００４３】
ここでポアに進入しない一定の接触角とは、ポアのサイズにより必要とされる表面張力が異なるため表面張力の値を数値化できないが、成膜後ポア部分に発生する海島状の平均膜厚より平均膜厚の２％以上薄い部分は２２５μｍ^２が上限であり、この範囲以上ではトラッキング精度、エラー訂正が不可能になるなどの問題が発生する。よって、ポアに溶液が浸透した場合でも上記の範囲以上に浸透が広がらなければ、ポアに進入しない一定の接触角を有する溶液と判断する。
【００４４】
反射層（５）に用いる材料には特に限定はないが、アルミニウム、銀、銅などの金属材料又はこれらを主成分とする合金材料を使用することができる。特に金を主体とする金属または合金を用いることが好適である。
銀を主体とするとは、銀の含有率が８０〜１００原子％、特に９０〜１００％であることが好ましい。
また、これらの反射層材料のうちでは、安価でありかつコンパクトディスクにおいて使用されて実績があることから、アルミニウムを使用することもできる。反射層材料として金属材料又は合金材料を用いる場合には、スパッタリングや真空蒸着などの真空成膜方法によって、反射層を形成することができる。この場合、真空槽内の真空度を変えて（例えば、１０^−５ｔｏｒｒ程度）スパッタリングを行ない、密度または結晶化の状態の違う膜を形成して金属反射層の反射率を高くする技術を適用することもできる。
【００４５】
保護層（１０）は、例えばＳｉＯ、ＳｉＮ、ＡｌＮ等の無機材料や、光硬化性樹脂などの有機材料を用いて形成することができる。無機保護層は、真空成膜方法によって形成することができ、有機保護層は、反射層（５）上に光硬化性樹脂膜（たとえば、大日本インキ化学工業（株）のＳＤ１７００、ＳＤ３１８、ＳＤ３０１）をスピンコートした後、樹脂硬化光を照射することによって形成できる。
また、高密度化を図るために、高ＮＡのレンズを用いる場合、保護層を光透過性とする必要となる。例えば高ＮＡ化すると、再生光が透過する部分の厚さを薄くする必要がある。これは、高ＮＡ化に伴い、光学ピックアップの光軸に対してディスク面が垂直からズレる角度（いわゆるチルト角、光源の波長の逆数と対物レンズの開口数の積の２乗に比例する）により発生する収差の許容量が小さくなるためであり、このチルト角が基板の厚さによる収差の影響を受け易いためである。
したがって、基板の厚さを薄くしてチルト角に対する収差の影響をなるべく小さくするようにしている。
【００４６】
そこで、例えば基板上に凹凸を形成して記録層とし、その上に反射層を設け、さらにこの上に光を透過する薄膜である光透過性の保護層を設けるようにし、保護層側から再生光を照射して記録層の情報を再生するような光記録媒体や、基板上に反射層を設け、その上に熱受容層、光吸収層を形成して記録層とし、さらにこの上に光透過性を有する保護層を設けるようにし、保護層側から再生光を照射して記録層の情報を再生するような光記録媒体が提案されている。このようにすれば、カバー層を薄型化していくことで対物レンズの高ＮＡ化に対応可能である。つまり、薄いカバー層を設け、このカバー層側から記録再生することで、さらなる高記録密度化を図ることができる。なお、このような保護層はポリカーボネートシートや、紫外線硬化型樹脂により形成されるのが一般的である。厚みは０．１ｍｍ以下が好適である。
【００４７】
本発明において、基板（１）は、レーザーに対して透明性を維持し、優れた衝撃強度を持っており、８０乃至２００℃の温度で容易に膨脹または変形、変質される材料からなる。このような特性を満足する材質としてはポリカボネート、ポリメチルメタクリレート、エポキシ樹脂、ポリエステル、非晶質ポリオレフィンなどがあり、ガラス転移温度（Ｔｇ）が１００乃至２００℃であることが望ましい。また、基板表面には、記録又は再生時、入射レーザー光を案内するためのプリグルーブが形成されており、その深さは１０乃至２００ｎｍであることが望ましい。プリグルーブの深さが１０ｎｍ未満の場合には、記録後基板膨脹により反射率が大きく増加されて記録信号にノイズが多くなり、２００ｎｍを超える場合には、熱受容層層にもプリグルーブが深く生じるため均一な成膜が得難い。
【００４８】
光吸収層（３）の熱伝導度は、１０（Ｗ／ｃｍ・℃）以下であることが望ましい。１０（Ｗ／ｃｍ・℃）を超過する場合には、レーザーにより金属記録膜から発生する熱が周囲に急速に伝導されて薄膜自体が必要な所定温度以上に加熱され難く、加熱されても記録ピットが大きいので隣接したトラックまで変形させる恐れがある。
さらに、光吸収層（３）の線膨脹係数は、３×１０^−７／℃以上であることが望ましい。前記範囲の未満なら、記録時基板の膨脹により金属記録膜に亀裂が生じ、よって均一の記録信号が得られない。
熱受容層を構成するために使用する溶媒は、溶解度が５ｍｇ／１ｍｌ以上が必要である。
【００４９】
一方、光吸収層には超解像技術を付加することも可能である。通常光ディスクの再生限界はλ／２ＮＡで表わされる（ここで、λは波長、ＮＡは光の絞り込み確度の正弦である。）。
この限界を超える分解能を実現するため、以下の超解像技術を適応する。
対物レンズでレーザ光を媒体の上に集光させた再生ビームの強度分布Ｉは下記式で表わされる。
【００５０】
【数５】
Ｉ＝Ｉ_０＊ｅｘｐ（−２（ｒ／ｒ_０）^２）
（ここで、Ｉ_０はレーザビームの中心部の強度、レーザビームの強度が１／ｅ^２になる半径をｒ_０としている。）
このように強度分布がガウス分布の再生ビームで記録媒体が加熱されると、ビームが照射された部分の温度分布も同じようにガウス分布に近いものとなる。
ビームの中心付近の温度が高い部分を再生領域とし、周辺部分の温度の低い部分を記録再生に関与しない部分とすることで実行的なビームスポットの経が小さくなり分解能が向上する。
ガウス分布では中心温度のおよそ０．６倍のところ、すなわち半径ｒ_０／２のところで傾斜が急になる。この部分にあわせると安定した記録再生が可能となる。
【００５１】
さらに、熱受容層はサーモクロミック色素を使用し、吸収係数の変化などの熱吸収層の光学的変化を利用して記録再生することもできる。
用いるサーモクロミック色素としてはスピロピラン、フルオラン、ビアントロン、トリアリールイミダゾールが使用可能である。
【００５２】
さらに、光吸収層は光を吸収し、光を電気エネルギーに変換し、その電気化学的酸化還元で熱吸収層に記録を行なうこともできる。
その場合、光吸収層はＧｅ、Ｓｉ、ＧａＡｓ、Ｇａｐ、ＣｄＳｅ、ＣｄＳ、ＺｎＯ、ＳｎＯ、ＴｉＯ、ＳｉＣなどが使用可能である。
また、熱受容層にはチオニン色素、インジゴ系色素、酸化タングステン、メロシアニン、フタロシアニン、ペリレンテトラカルボン酸、ローダミン、キナクリドン、ポリアセチレン、ポリ（３−メチルチオフェン）、ポリ（Ｎ−メチルピロール）が使用可能である。
【００５３】
図１７は、本発明の光情報記録媒体の各界面での反射光の合成光を説明するための図である。図中の各信号は下記の通りである。
１：ポリカーボネイト製基板
４：有機色素製記録層
３：ＳｉＣ製薄層
１，３の間の空隙：空気（空隙）
５：Ａｇ反射層
ｎ０：ａｉｒの屈折率（ｎ０＝１）
ｎ１：ＰＣの屈折率（ｎ１＝１．６）
ｎ２：ＳｉＣの屈折率（ｎ２＝２．８）
ｎ３：ｄｙｅの屈折率（ｎ３＝１．４）
ｎ４：Ａｇの屈折率（ｎ４＝０．１）
ｄ１：空洞の厚さ
ｄ２：ＳｉＣの膜厚
ｄ３：ｄｙｅの厚さ
ｄ４：Ａｇの膜厚
Ａ１：ＰＣと空洞の界面での反射光
Ａ２：空洞とＳｉＣの界面での反射光
Ａ３：ＳｉＣとｄｙｅの界面での反射光
Ａ４：ｄｙｅとＡｇの界面での反射光
Ａ５：ＡｇとＰＣの界面での反射光
各界面の反射光Ａ１〜Ａ５は、下式で表わすことができる。
【００５４】
【数６】
Ａ１＝γ１０ｃｏｓθ　　　　　　　　　　　　　　　　　　　　　　　　………（１）
Ａ２＝ｔ１０γ０２ｔ０１ｃｏｓ（θ＋４πｎ０ｄ１／λ）　　　　　　　　　　　　　　　………（２）
Ａ３＝ｔ１０ｔ０２γ２３ｔ２０ｔ０１ｃｏｓ（θ＋４π（ｎ０ｄ１＋ｎ２ｄ２）／λ）　　　　　　　　………（３）
Ａ４＝ｔ１０ｔ０２ｔ２３γ３４ｔ３２ｔ２０ｔ０１ｃｏｓ（θ＋４π（ｎ０ｄ１＋ｎ２ｄ２＋ｎ３ｄ３）／λ）　　　………（４）
Ａ５＝ｔ１０ｔ０２ｔ２３ｔ４１γ４１ｔ１４ｔ３２ｔ２０ｔ０１ｃｏｓ（θ＋４π（ｎ０ｄ１＋ｎ２ｄ２＋ｎ３ｄ３＋ｎ４ｄ４）／λ）………（５）
したがって各界面の反射光Ａ１〜Ａ５の合成した光（Ａ１＋Ａ２＋Ａ３＋Ａ４＋Ａ５）＝ａ’ｃｏｓ（θ＋Δ）を解いて、ａ’をγ、ｔ、ｎ、ｄ、λで表わし、それぞれの値を代入して２乗したものが、エネルギー反射率Ｒとなる（ａ０＝１のため）。
ここでは代表例として記録中央部分の計算を示したが、実際には計算の場所をわずかにかえ、各層の形状の影響を考慮する必要がある。
また、ここでは変質の影響を加味していないが、この影響は変形とともに考慮する必要がある。
さらに、上記式では各層間での多重反射を考慮していないが実際には適宜考慮の必要がある。
【００５５】
具体的には図２１に記載の内容となる。ここでは簡単のために、３層構造を考えると、反射波Ｃの複素振幅は、１回反射光Ｃ_１、２回反射光Ｃ_２、３回反射光Ｃ_３、…の和で表わされる。
したがって、反射波の複素振幅の和Ｃは等比級数で表わされる。
【００５６】
【数７】
Ｃ＝｛ｒ＋ｔｔ’ｒ’ｅ^ｊδ（１＋ｒ’^２ｅ^ｊδ＋ｒ’^４ｅ^２ｊδ＋…）｝Ａ_０
【００５７】
以下に、本発明の情報記録媒体及びその製法について、図１８〜２０に基づき具体的に説明する。
図１８は本発明に係る光情報記録媒体の一例を示す要部拡大断面図である。この図から明らかなように、本例の光情報記録媒体は、透明基板（１）のプリフォーマットパターン形成面に下地層（６）を形成している。下地層（６）は、透明基板（１）と光吸収層（３）との密着性の改善や記録感度の改善、それに光吸収層（３）の保護等および熱吸収層として設けられるものであって、例えばポリビニルアルコール、ポリエチレンオキシド、ポリアクリル酸、ポリスチレンスルホン酸ナトリウム、ポリビニルピロリドン、ポリメタクリル酸、ポリプロピレングリコール、メチルセルロース、ポリビニルナイトレート、ニトロセルロースなどの親水性樹脂によって形成される。下地層（６）の形成は、親水性樹脂の水溶液を、透明基板（１）のプリフォーマットパターン形成面（２）にスピンコートすることによって行なえる。
なお、下地層（６）は、親水性樹脂よりなっているため、耐水性（耐湿性、透湿性）及び耐熱性が悪い。したがって、下地層（６）には、架橋処理や結晶化処理を施して、耐水性及び耐熱性を改善することが好ましい。具体的には、親水性樹脂の水溶液に架橋剤を添加して下地層（６）を成膜した後に、光照射による架橋反応や加熱による架橋反応を起こさせたり、あるいは架橋剤の添加のない下地層（６）を熱処理して結晶化（例えば、親水性樹脂としてポリビニルアルコール（ＰＶＡ）を用いる場合には、ＰＶＡを変性ＰＶＡ化する。）させる。
【００５８】
架橋処理と結晶化処理とを比較すると、加熱による悪影響を透明基板（１）に与えることがなく、かつ作業性にも優れていることから、結晶化処理よりも架橋処理の方が好ましい。以下に、架橋反応の具体例を示す。実施に際しては、これらの架橋反応から、必要に応じて任意の手段を採用することができる。
（Ｉ）架橋剤として、重クロム酸アンモニウムを添加し、色素表面を処理すると同時に、成膜後反応光を照射して、下地層に架橋反応を起こさせる方法。
（ＩＩ）無機系架橋剤として、例えば銅、ホウ素、アルミニウム、チタン、ジルコニウム、スズ、バナジウム、クロム等を添加する方法。
（ＩＩＩ）アルデヒドを用いてアセタール化する方法。
（ＩＶ）水酸基をアルデヒド化する方法。
（Ｖ）活性化ビニル化合物を添加する方法。
（ＶＩ）エポキシ化合物を添加してエテール化する方法。
（ＶＩＩ）酸解媒のもとでジカルボン酸反応を起させる方法。
（ＶＩＩＩ）コハク酸及び硫酸を添加する方法。
（ＩＶ）トリエチレングリコール及びアクリル酸メチルを添加する方法。
（Ｘ）ポリアクリル酸及びメチルビニルエテールマレイン酸共重合体をブレンドする方法。
【００５９】
下地層（６）は、光エネルギを吸収して熱エネルギに変換する材料、若しくはこの種のイオン性の色素材料を少なくとも一部に含むヒートモード記録材料を、前記プリフォーマットパターン（２）内に充填することによって形成される。
下地層（６）を形成可能な色素材料としては、例えばポリメチン系色素、アントラキノン系色素、シアニン系色素、フタロシアニン系色素、ナフタロシアニン系色素、キサンテン系色素、トリフェニルメタン系色素、ピリリウム系色素、アズレン系色素、含金属アゾ染料、アゾ染料等を挙げることができる。これらのうちでは、ジカルボシアニン誘導体、フタロシアニン誘導体、ナフタロシアニン誘導体、シアニン誘導体、アゾ染料誘導体が特に好適に用いられる。また、アミニウム系色素などの各種クエンチャが添加された色素材料を用いることもできる。さらには、上記色素材料群より選択される１種又は２種以上の色素材料を樹脂中に分散したものを、下地層（６）の形成材料として用いることもできる。色素材料を分散可能な樹脂材料としては、アクリル樹脂、ビニル樹脂、フェノール樹脂、フッ素樹脂、シリコーン樹脂、ポリアミド樹脂、セルロース樹脂などを挙げることができる。
【００６０】
また、下地層（６）は、透明基板（１）のプリフォーマットパターン形成面に、先に例示的に列挙された色素材料群より選択された色素材料の溶剤溶液をスピンコートし形成する。さらに溝状のプリフォーマットパターン（２）内に色素材料を充填した後、プリフォーマットパターン（２）の間のランド部（２ｃ）に付着した色素材料を選択的に除去し、透明基板（１）の表面を露出すると共に、プリフォーマットパターン（２）内にのみ色素材料を充填することによって形成できる。なお、色素材料の溶剤としては、アルコール系溶剤あるいはセルソルブ系溶剤などを用いることができる。
【００６１】
さらに、以下に示す二座配位子を取りうるキレート材を含有し、本発明の目的を達成することもできる。たとえば、無機酸類、ジカルボ酸類、オキシカルボ酸類、ジオキシ化合物、オキシオキシム類、オキシアルデヒドおよび誘導体類、ジケトン類および類似化合物、オキシキノン類、トロボロン類、Ｎ−オキシド化合物、アミノカルボン酸および類似化合物、ヒドロキシルアミン類、オキシン類、アルジミン類、オキシオキシム類、オキシアゾ化合物、ニトロソナフトール類、トリアゼン類、ピウレット類、ホルマザン類およびジチゾン類、ビクアリド類、グリオキシム、ジアミン類および類似化合物、ヒドラジン誘導体、チオエーテル類がある。さらに、イミノ基（イミド、アミド）を有する誘導体も使用可能である。
【００６２】
また、上記の有機材料の他、原子配列を変化し情報の記録ができる相変化材料も使用可能である。
具体的にはＡ−Ｂ−Ｃ−Ｇｅ−Ｔｅで代表される金属、および合金である。
ここでＡはＣｕ、Ａｇ、Ａｕ、Ｓｃ、Ｙ、Ｔｉ、Ｚｒ、Ｖ、Ｎｂ、Ｃｒ、Ｍｏ、Ｍｎ、Ｆｅ、Ｒｕ、Ｃｏ、Ｒｈ、Ｎｉ、Ｐｄ、Ｈｆ、Ｔａ、Ｗ、Ｉｒ、Ｐｔ、Ｈｇ、Ｂ、Ｃ、Ｎ、Ｐ、Ｏ、Ｓ、Ｓｅ、ランタニド元素、アクチニド元素、アルカリ土類金属元素、不活性ガス元素、などのうち少なくとも一つの元素を表わす。
ＢはＴｌ、Ｉなどハロゲン元素、およびＮａなどのアルカリ金属元素のうち少なくとも一元素を表わす。
ＣはＳｂ、Ｓｎ、Ａｓ、Ｐｂ、Ｂｉ、Ｚｎ、Ｃｄ、Ｓｉ、Ａｌ、ＧａおよびＩｎのうち少なくとも一元素を表わす。
また、光磁気材料に使用される金属材料、たとえば上記金属元素のＴｂ、Ｆｅ、Ｃｏなども記録層として使用可能である。
【００６３】
さらに、Ｆｅ、Ｔｉ、Ｚｒ、Ｔａ、Ｃｒ、Ｍｏ、Ｗ、Ｎｉ、Ｒｈ、Ｐｄ、Ｐｔ、Ｃｕ、Ａｇ、Ａｕ、Ｚｎ、Ａｌ、Ｉｎ、Ｓｉ、Ｇｅ、Ｔｅ、Ｓｎ、Ｂｉ、Ｓｂ、Ｔｌ、およびＰｔからなる群より選ばれる少なくとも一種の物質からなるか、または、芳香族化合物、脂肪族化合物、アミド、エステル、アミン、ウレア、硫黄化合物及びヒドロキシ化合物からなる群から選択される少なくとも１つのものであるか、またはアントラキノン系、ダイオキシディン系、トリフェノジチアジン系、フェナントレン系、シアニン系、フタロシアニン系、ナフタロシアニン系、メロシアニン系、ピリリウム系、キサンテン系、トリフェニルメタン系、クロコニウム系、アゾ系、インジゴイド系、メチン系、アズレン系、スルファイド系及びメタンジチオールレート系の色素からなる群から選択される少なくとも１つの色素であるか、または５０重量％以下の高分子物質を含み、高分子物質は、ビニールアルコール系樹脂、ビニールアセテート系樹脂、アクリルレート系樹脂、ポリエステル系樹脂、ポリエーテル系樹脂、ポリスチレン系樹脂、ポリウレタン系樹脂、セルロース系樹脂及び脂肪酸系樹脂からなる群から選択された少なくとも１つのもの、またはアルミニウム、銀、銅などの金属材料、ＳｉＯ、ＳｉＮ、ＡｌＮ、ＳｉＣ、ＺｎＯ_２等の無機材料が使用可能であり、特に金を主体とする金属または合金を用いることが好適である。
銀を主体とするとは、銀の含有率が８０〜１００原子％、特に９０〜１００％であることが好ましい。
【００６４】
下地層（６）の厚さは、５〜２００ｎｍが好適である。
膜厚が５ｎｍより薄いと成膜が安定しない。また、膜厚が２００ｎｍより厚い場合、体積が大きすぎるため、変形や熱の伝達、穴形成が不充分となる。
ＳｉＣを選択した場合、膜厚は８〜１４ｎｍが好適である。
Ａｇを選択した場合は膜厚１０〜４０ｎｍが好適であった。
この層にはマイクロポアが存在し、中には貫通している連続気泡タイプが存在する。
【００６５】
また、図１９は、本発明に係る光情報記録媒体の別の例を示す要部拡大断面図である。この図から明らかなように、本発明の光情報記録媒体は、光吸収層（３）と熱受容層（４）の間に中間層（７）を介して積層している。中間層（７）は、情報記録部（３）と反射層（４）との密着性の改善や記録感度の改善、それに情報記録部（３）の保護等のために設けられるものであって、下地層（６）と同種の親水性樹脂または光吸収層（３）の材料を使用することができる。中間層（７）の材料に、親水性樹脂を選択した場合、その水溶液を情報記録部（３）上にスピンコートすることによって行なえる。当該中間層（７）についても、耐水性及び耐熱性を改善するため、スピンコートされた中間層（７）に、架橋処理や結晶化処理を施すことが好ましい。架橋処理及び結晶化処理は、下地膜同様の方法で行なえる。
【００６６】
図２０は本発明のディスク製造のフローチャートの一例である。
以下、手順を具体的に説明する。
Ｓ１：ガラス円盤を研磨、洗浄する。
Ｓ２：シランコート
Ｓ３：ガラス円盤上にフォトレジストをスピンコートし、所定の膜厚を有するレジスト層を形成する。
Ｓ４：溶剤をとばすためプリベークを行なう。
Ｓ５：レジスト層に集光レンズを介してレーザを照射する（カッティング）。
Ｓ６：この露光済みガラス円盤の現像処理する。
Ｓ７：レジストをＴｇ以上に加熱し溝形状を整形する（第一ベーク）。
Ｓ８：パターンの固化のためベークを行なう（第二ベーク）。
Ｓ９：蒸着、メッキ
Ｓ１０：ガラス円盤の凹凸面に金属膜を形成し、それを剥離することによりスタンパーを作成する。
Ｓ１１：スタンパーを用いて射出成形を行ない、所定の膜厚を有するレプリカ層を形成する。
Ｓ１２：透明基板の片側にスピンコート法によりハードコート層を形成する。
Ｓ１３：透明基板の片面に必要に応じてスピンコート法またはスパッタ法により下地層を形成する。
Ｓ１４：下地層の上面にスピンコート法またはスパッタ法で光吸収層を形成する。
Ｓ１５：光吸収層上に熱受容層を形成する。
Ｓ１６：熱受容層上に反射層を形成する。
Ｓ１７：必要に応じ保護層、他の層を積層し、単板に状態にて使用する場合。
Ｓ１８：必要に応じ保護層、他の層を積層し、それぞれのディスクを張り合わせ両面ディスクとする。
Ｓ１９：このディスクをカートリッジに収納する。
Ｓ２０：特性の評価を行なう。
このフローチャートに関して、Ｓ７およびＳ８は同時に行なうこともできる。溝形状の整形には加熱温度９０度以上１８０度以下、時間は５から９０分で任意に選択できる。
なお、この説明においては、ディスク状記録媒体を例に挙げたが、本発明はこれに限定されるものではなく、例えばカード状、スティック状あるいはテープ状など、他の形態の情報記録媒体にも応用できることは勿論である。
【００６７】
【実施例】
以下に、本発明を実施例に基づき具体的に説明する。
図１及び図２に示すプリフォーマットパターンを有するポリカーボネート基板に、ＳｉＣ膜をスパッタ法にて成膜し、さらにその上に下記（化１）で示される色素の混合物からなる有機材料層をスピンコート法によって形成し（平均膜厚１００ｎｍ）、熱吸収層を形成した。
この熱吸収層上にスパッタ法により厚さ１００ｎｍの銀膜を形成し反射層とした。反射層上に大日本インキ化学工業（株）のＳＤ１７００（熱伝導率１．０以下）を膜厚５μｍで積層し保護層とした。さらに保護層上にＵＶ硬化性のインク層を設けた。具体的にはＤＩＣＵＶインク（大日本インキ化学工業（株））を０．１ｇから７．０ｇの範囲で積層した。
上記光記録媒体に対し、パルステック工業（株）製の光ディスク評価装置ＤＤＵ−１０００（波長：４０５ｎｍ、ＮＡ：０．６５）を用いて、以下の条件で記録を行なった。
その結果は、短マーク＝０．３μｍ、変調度３０％、長マーク＝１．０μｍ、変調度６０％で、短マーク、長マークとも、変調度が充分大きく、非常に明瞭な信号が得られた。
【００６８】
【化１】

【００６９】
（記録条件）
記録線速度：６．０（ｍ／ｓ）
記録ストラテジ：Ｂａｓｉｃ　ｓｔｒａｔｅｇｙ　Ｔｔｏｐ−Ｔｍｐ＝
１．４０−０．７５（Ｔ）
記録パワー：１１．０（ｍｗ）
記録パターン：３Ｔ、４Ｔ、５Ｔ、８Ｔ、１４Ｔの単一周期信号
【００７０】
上記の記録条件は情報記録媒体の記録部を観察しながら決定した。その方法は、まず熱受容層を剥離する。本実施例では変質部の色素材が反射層に優先的に癒着し、非変質部は光吸収層側に優先的に癒着した。
さらに、剥離した反射層、および光吸収層にエタノールを滴下し変質の範囲を測定し、その結果を記録条件に反映し、上記の条件を見い出した。
【００７１】
記録部の断面の様子をランドに記録した場合を図１５に、グルーブに記録した場合を図１６に示す。図１５および１６よりわかるように、本実施例では熱受容層は記録スポットの中央部の色素量が低下し、記録スポット径の外側まで変質が見られた。ここで用いた記録スポット径ｒとはｒ＝λ／２ＮＡ×Ｋ（但し、Ｋ＝０．６〜１．２２）で表わされる範囲である。
また、光吸収層は基板と反対側に凸状となり、基板は凹状の変形をした。
【００７２】
この媒体では光吸収層に１０個以上のφ＝２μｍのポア、４個のφ＝５μｍのポア、一個φ＝１０μｍのポアが存在し、この影響により、２２５μｍ２の範囲で、平均膜厚より平均膜厚の２％以上薄い部分があったが、プレヤーでエラー訂正され良好に再生することができた。
また、ポアが存在しない部分でも島状に平均膜厚より平均膜厚の２％以上薄い部分が確認できた。この部分は連続気泡ではなく、独立気泡となっている。
なお、４０５ｎｍにおける（化１）の複素屈折率は１．４８５−ｉ　０．０６９である。
【００７３】
本実施例により、本発明の光記録媒体の層構成と記録原理が、青色レーザ波長対応の有機材料からなる追記型光記録媒体の実現に非常に有効であることが確認できた。また、本発明の光記録媒体の層構成と記録原理が、青色レーザ波長対応の高変調度が確保できる追記型光記録媒体の実現に非常に有効であることが確認できた。
【００７４】
【発明の効果】
以上、詳細且つ具体的な説明より明らかなように、請求項１の発明は、色素材料を含む熱受容層を膜厚２００ｎｍ以下になるように光吸収層の上に積層した層構造を有する情報記録媒体に係るものであって、この媒体にガウス分布を示す光を照射し記録した結果、熱受容層が、記録のため光強度を高くした記録マーク領域の内側、およびその外側の部分が変質したことにより大きなコントラストを得ることができるとともに、基板が傾いた場合にも信号には変化がなく、傾き等の影響を受けにくいという効果を有する。
請求項２の発明は、色素材料を含む熱受容層を膜厚２００ｎｍ以下になるように光吸収層の上に積層した層構造を有する情報記録媒体に係るものであって、この媒体にガウス分布を示す光を照射し、記録した結果、ガウス分布の中央部に対応する部分の熱受容層中の成分量が外周部より減少していることにより、大きなコントラストを得ることができ、良好に記録することができる。また、請求項３の発明は、請求項１又は２に記載の情報記録媒体において、色素材料をシアニン系、フタロシアニン系、ナフタロシアニン系、メロシアニン系、アゾ系及びホルマザンキレート系からなる群から選択される少なくとも一つの色素に限定したものであって、さらに大きなコントラストを得ることができる。請求項４の発明は、ガウス分布を示す光を照射することにより熱受容層の変質に加え、少なくとも熱受容層が変形しているものであり、これにより、より高いコントラストを得ることができる。請求項５の発明は熱受容層が記録のため光強度を高くした範囲、すなわち、記録マーク領域の内側、およびその外側の部分が変質することで大きなコントラストを得ることができ、良好に記録することができる。また、請求項６の発明は、熱受容層上に反射層を積層しており、反射層／熱受容層界面を反射の担い手としたものであって、これによれば、光照射により変質し剥離した熱受容層の色素材料は上記反射層界面に癒着することになり、これは上記界面の部分からの反射光を制御する意味で重要である。このことにより、大きなコントラストを得ることができ、良好に記録することができる。
請求項７の発明は、記録マーク領域の範囲がｒ＝λ／ＮＡ×０．８（λは記録に用いる波長、ＮＡはレンズの開口率を表わす。）のスポットを照射し移動して得られる範囲としているので、隣のトラックへの影響が少なく、ジッターの小さい良好な記録をすることができる。請求項８の発明は、熱受容層の変質により、密着性が変化し剥離させるもので、このことは、変質部と非変質部とがそれぞれ上下の別の層に優先的に密着し、剥離するまで変質を促進していることを意味し、このことにより、大きなコントラストを得ることができる。
請求項９の発明は、熱受容層の変質が材料の分解、昇華、溶融により起こり、その光学的性質変化を見る目安として溶解特性を用いたものであり、溶解特性が変化するまでの範囲の変質を誘発することにより、大きなコントラストを得ることができる。
請求項１０の発明は、例えば記録領域において記録−未記録−記録というように形成した未記録部分の見かけ上の光学特性の変化量が、記録を行っていない未記録領域の光学特性の値に対して相対値で±５０％以内としているので、記録領域の未記録部と未記録領域の未記録部との反射率の差が小さくなり、記録領域から続けて未記録領域を再生、記録する場合でも、光ピックアップが安定してトラックを追随できる。
請求項１１の発明は、記録部の見かけ上の光学特性の変化が記録により反射率が低下するように設定したものである。通常、情報記録媒体は記録前にアドレスを示す、プリピットなどが存在し、その信号は反射率が低下する方向に設定されているが、記録後の信号も同じく反射率が低下する方向である方が、信号を検出する方向が同じであるため、回路の設計などが容易となる。
請求項１２の発明は、前記変質部と非変質部に溶媒を浸透させ、溶解性を比較して、変質部を確認するもので、簡便に記録範囲を確認することができる。これにより、その情報を簡便に記録条件に反映でき、良好な記録をすることができる。
【図面の簡単な説明】
【図１】本発明に係る光情報記録媒体の構成を表わす要部拡大断面図の一例である。
【図２】本発明に係る光情報記録媒体の平面図である。
【図３】本発明に係る光情報記録媒体の記録の状態を表わす要部拡大断面図の一例である。
【図４】本発明に係る光情報記録媒体の記録の状態を表わす要部拡大断面図の他の例である。
【図５】本発明に係る光情報記録媒体の記録の状態を表わす要部拡大断面図の他の例である。
【図６】本発明に係る光情報記録媒体の記録の状態を表わす要部拡大断面図の他の例である。
【図７】本発明に係る光情報記録媒体の記録の状態を表わす要部拡大断面図の他の例である。
【図８】本発明に係る光情報記録媒体の記録の状態を表わす要部拡大断面図の他の例である。
【図９】本発明に係る光情報記録媒体の記録の状態を表わす要部拡大断面図の他の例である。
【図１０】本発明に係る光情報記録媒体の記録の状態を表わす要部拡大断面図の他の例である。
【図１１】本発明に係る光情報記録媒体の記録の状態を表わす要部拡大断面図の他の例である。
【図１２】本発明に係る光情報記録媒体の記録の状態を表わす要部拡大断面図の他の例である。
【図１３】本発明に係る光情報記録媒体の記録の状態を表わす要部拡大断面図の他の例である。
【図１４】本発明に係る光情報記録媒体の記録の状態を表わす要部拡大断面図の他の例である。
【図１５】本発明に係る光情報記録媒体の変質の様子を表わす要部拡大断面図の一例である。
【図１６】本発明に係る光情報記録媒体の変質の様子を表わす要部拡大断面図の他の例である。
【図１７】本発明に係る光情報記録媒体の各界面での反射光の合成光を説明するための図である。
【図１８】本発明に係る光情報記録媒体の構成を表わす要部拡大断面図の他の例である。
【図１９】本発明に係る光情報記録媒体の構成を表わす要部拡大断面図の他の例である。
【図２０】本発明に係る光情報記録媒体製造のフローチャートである。
【図２１】各層間での多重反射を説明するための図である。
【符号の説明】
１　透明基板
２　プリフォーマットパターン
３　光吸収層（情報記録部）
４　熱受容層
５　反射層
６　下地層
７　中間層
１０　保護層
１ａ　センタ孔
２ａ　案内溝
２ｂ　プリピット
２ｃ　ランド部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an information recording medium on which information can be recorded and reproduced by a laser, a recording method thereof, and a means for checking a recording section of the medium, and is applied to an optical information recording medium.
[0002]
[Prior art]
In the prior art, as in the present invention, the inner and outer portions of the recording mark area deteriorate until the solubility changes, or the amount of the dye layer material in the portion corresponding to the central portion of the Gaussian distribution is larger than that in the outer peripheral portion. There is no mention of an optical information recording medium characterized by a small number.
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 a conventional write-once optical recording medium, recording pits are formed by irradiating a recording layer made of an organic material with a laser beam and causing a change in the refractive index mainly due to decomposition and deterioration of the organic material. The optical constant and decomposition behavior of the organic material used for the recording are important factors for forming a good recording pit.
Therefore, as the organic material used for the recording layer, it is necessary to select an appropriate material having optical properties and decomposition behavior with respect to the blue laser wavelength.
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). Is selected so as to be located on the long wavelength side of the bottom. The reason is that the long wavelength side of the large absorption band has a suitable absorption coefficient and a wavelength region where a large refractive index can be obtained.
[0003]
However, no material has been found in which the optical properties with respect to the wavelength of the blue laser have a value comparable to that of the conventional art. In order to make the absorption band of the organic material near the blue laser wavelength, it is necessary to reduce the molecular skeleton or shorten the conjugated system, but this reduces the absorption coefficient, that is, the refractive index. It is to invite. 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 there is no large refractive index, a large modulation degree cannot be obtained.
[0004]
Patent Documents 1 to 5 and the like are described, for example, as organic materials compatible with a blue laser.
However, in these publications, the examples only measure the spectra of the solution and the thin film, but do not describe recording and reproduction.
[0005]
Although Patent Documents 6 to 8 describe recording in Examples, the recording wavelength is 488 (nm), and there is no description about recording conditions or recording density, indicating that good recording pits could be formed. Is only described.
In Patent Document 9, although recording is described in Examples, the recording wavelength is 430 (nm), and there is no description about recording conditions or recording density, and it is described that a good degree of modulation was obtained. There is only.
[0006]
Patent Documents 10 to 19 include examples in which recording is performed at a recording wavelength of 430 (nm) and NA of 0.65 in Examples, but a low recording density condition that the shortest pit is 0.4 (μm) (recording density equivalent to that of DVD) ).
Patent Document 20 has a recording / reproducing wavelength of 405 to 408 (nm), but does not specifically describe the recording density, and is a low recording density condition of recording a 14T-EFM signal.
[0007]
Further, regarding the layer configuration and recording method different from the conventional CD and DVD optical recording media, the following techniques are disclosed.
Patent Document 21 describes a technique of performing recording by changing the extinction coefficient (absorption coefficient in the present invention) of a saturable absorbing dye in a configuration of a substrate / a saturable absorbing dye-containing layer / a reflective layer. Patent Literature 22 describes a technique in which recording is performed by discoloring or deforming a metal vapor-deposited layer by heat generated by the light-absorbing layer in a configuration of a substrate / metal-deposited layer / light-absorbing layer / protective sheet. Patent Document 23 discloses a technique of performing recording by changing the thickness of a recording layer and the depth of a groove in a structure of a substrate / a dielectric layer / a recording layer including a light absorber / reflection layer. Patent Document 24 describes a technique of performing recording by changing the thickness of a recording layer by 10 to 30% in a configuration of a substrate / a recording layer including a light absorber / a metal reflection layer. In Patent Document 25, Patent Document 1 discloses a technique of performing recording by increasing the groove width of a substrate by 20 to 40% with respect to an unrecorded portion in a configuration of a plate / a recording layer containing an organic dye / a metal reflective layer / a protective layer. Document 26 describes a technique of performing recording by deforming a metal thin film to form a bubble in a structure of a substrate / intermediate layer / metal thin film, and Patent Document 27 describes a technique of recording a substrate / light absorbing layer / recording. A technique of performing recording by deforming a recording auxiliary layer into a concave shape with a configuration of an auxiliary layer / light reflecting layer and deforming a light reflecting layer into a concave shape along with the deformation of the recording auxiliary layer is described. Reference numeral 28 denotes a substrate / light absorbing layer / porous recording auxiliary layer / light reflecting layer, or a substrate / porous recording auxiliary layer / light absorbing layer / light reflecting layer, which deforms the recording auxiliary layer into a concave shape. Along with the deformation of the recording auxiliary layer Patent Document 29 describes a technique for performing recording by deforming a light reflecting layer in a concave shape along the line. Patent Document 29 discloses a substrate / porous light absorbing layer / light reflecting layer in which a light absorbing layer is formed in a concave shape. A technique for performing recording by deforming the light reflecting layer in a concave shape along with the deformation of the light absorbing layer is described. Patent Document 30 discloses a substrate / a recording layer containing an organic dye / a recording auxiliary layer. With this configuration, a recording technique is described in which a recording auxiliary layer and an organic dye are compatible with each other and the absorption spectrum of the organic dye is shifted to a shorter wavelength side.
However, the above technique is not aimed at realizing an optical recording medium in the blue laser wavelength region, and is not a layer configuration or a recording method effective in the blue laser wavelength region.
[0008]
As described above, at the present stage, in the blue laser wavelength region, particularly in the vicinity of 405 (nm), which is the center of the oscillation wavelength of the blue semiconductor laser currently practically used, the recording layer of the conventional write-once optical recording medium is formed. Few organic materials have optical constants comparable to the required optical constants.
Further, there is no example in which recording conditions are clarified near 405 (nm) and recording is performed at a higher recording density than that of DVD.
Further, the examples in the above publications are experiments with a conventional disk configuration, and described a layer configuration, a recording principle, and a recording method for easily realizing a write-once optical recording medium made of an organic material in a blue laser wavelength region. There are no valid suggestions.
[0009]
Conventionally, in a write-once type optical recording medium made of an organic material, the wavelength dependence of the optical constant of the organic material is large (the optical constant fluctuates greatly depending on the wavelength). However, there is a problem that recording characteristics such as recording sensitivity, modulation degree, jitter and error rate, reflectivity, and the like are greatly changed with respect to fluctuations in recording / reproducing wavelength due to the above factors.
[0010]
[Patent Document 1]
JP 2001-181524 A
[Patent Document 2]
JP 2001-158865 A
[Patent Document 3]
JP 2000-343824 A
[Patent Document 4]
JP 2000-343825 A
[Patent Document 5]
JP 2000-335110 A
[Patent Document 6]
JP-A-11-221964
[Patent Document 7]
JP-A-11-334206
[Patent Document 8]
JP 2000-43423 A
[Patent Document 9]
JP-A-11-58955
[Patent Document 10]
JP 2001-39034 A
[Patent Document 11]
JP-A-2000-149320
[Patent Document 12]
JP 2000-113504 A
[Patent Document 13]
JP 2000-108513 A
[Patent Document 14]
JP 2000-222772 A
[Patent Document 15]
JP 2000-218940 A
[Patent Document 16]
JP-A-2000-222771
[Patent Document 17]
JP 2000-158818 A
[Patent Document 18]
JP 2000-280621 A
[Patent Document 19]
JP 2000-280620 A
[Patent Document 20]
JP 2001-146074 A
[Patent Document 21]
JP-A-7-304258
[Patent Document 22]
JP-A-8-83439
[Patent Document 23]
JP-A-8-138245
[Patent Document 24]
JP-A-8-2977838
[Patent Document 25]
JP-A-9-198714
[Patent Document 26]
Japanese Patent No. 2506374
[Patent Document 27]
Japanese Patent No. 2591939
[Patent Document 28]
Japanese Patent No. 2591940
[Patent Document 29]
Japanese Patent No. 2591941
[Patent Document 30]
Japanese Patent No. 2982925
[0011]
[Problems to be solved by the invention]
Therefore, an object of the present invention is to realize a write-once optical recording medium made of an organic material even in the blue laser wavelength region, particularly in the wavelength region near 405 (nm), in view of the above-mentioned conventional technology. A write-once optical recording medium with a large degree of modulation is realized.Furthermore, a change in recording characteristics such as recording sensitivity, modulation degree, jitter and error rate, and a change in reflectivity are small with respect to fluctuations in the recording / reproducing wavelength. To realize an optical recording medium.
[0012]
[Means for Solving the Problems]
An object of the present invention is to provide (1) an information recording medium having a layer structure in which a heat receiving layer containing a dye material is laminated on a light absorbing layer so as to have a thickness of 200 nm or less. Irradiation with light exhibiting a Gaussian distribution, and recording, as a result, the information is characterized in that the heat receiving layer is changed by altering the inside and outside portions of the recording mark area where the light intensity is increased for recording. (2) An information recording medium having a layer structure in which a heat-receiving layer containing a dye material is stacked on a light-absorbing layer so as to have a thickness of 200 nm or less, and the medium has a Gaussian distribution. The information recording medium is characterized in that the amount of the dye material is reduced from the outer peripheral portion due to deterioration of the dye material in the heat receiving layer in a portion corresponding to the central region of the Gaussian distribution as a result of irradiating the light shown in FIG. , (3) "The pigment material is The above item (1) or (2), which is at least one dye selected from the group consisting of anine, phthalocyanine, naphthalocyanine, merocyanine, azo and formazan chelate dyes. (4) The information recording medium according to any one of (1) to (3), wherein at least the heat receiving layer is deformed by irradiation with light having a Gaussian distribution. (5) The information recording medium described in (5), wherein the heat receiving layer is recorded by altering portions inside and outside of a recording mark area whose light intensity is increased for recording. (2) The information recording medium according to any one of the above items (4) to (6), wherein the reflective layer is further laminated on the heat receiving layer. Any of (5) (7) r = λ / 2NA × K (where λ is the wavelength used for recording, NA is the aperture ratio of the lens, and K = 0.6 to 1.22) The information recording medium according to any one of (1) to (6), wherein a region obtained by irradiating a laser spot represented by the following formula and moving this spot is used as a mark region. (8) "The heat receiving layer is characterized in that the deteriorated portion and the non-transformed portion are peeled off due to deterioration, and the heat receiving layer selectively adheres to another adjacent layer. (7) The information recording medium according to any one of the above (1) to (9), wherein the deterioration of the heat receiving layer can be confirmed as a change in the melting characteristics of the material after film formation. The information recording medium according to any one of the items (8) ".
[0013]
Further, an object of the present invention is to provide (10) a method for recording information using the information recording medium according to any one of the above (1) to (9), An information recording method characterized in that the apparent amount of change in optical characteristics of an unrecorded portion is set to be within ± 50% as a relative value with respect to the value of the optical characteristics of the unrecorded portion before recording. (11) The recording method for an information recording medium according to the above (10), wherein the change in the apparent optical characteristics of the recording section is set so that the reflectivity decreases by recording. Is solved by.
[0014]
In addition, the above object is (12) in the present invention, in the information recording medium according to the above (8), characterized in that a solvent is permeated into the altered portion and the non-altered portion, and the solubility is compared. Confirmed method of altered part ".
[0015]
That is, the above items (1) to (6) are blue laser wavelength regions in which it is difficult to obtain an optical constant similar to the optical constant required for the recording layer of the conventional write-once optical recording medium. It is another object of the present invention to provide a layer structure of a write-once optical recording medium capable of achieving high density and a high degree of modulation, and a recording principle of the optical recording medium.
Item (7) is to provide a method for confirming the modification of the recording section.
Item (8) is to provide a recording principle in an optical recording medium.
The items (9) and (10) are used even in a blue laser wavelength region where it is difficult to obtain an optical constant similar to the optical constant required for the recording layer of the conventional write-once optical recording medium. Another object of the present invention is to provide a recording method that can achieve high density and obtain a high modulation degree.
[0016]
In order to achieve the above object of the present invention, the present invention provides a write-once optical recording medium having a light absorbing layer and a heat receiving layer adjacent to the light absorbing layer. In order to achieve the above, in the present invention, using a write-once optical recording medium having a light absorbing layer and a heat receiving layer adjacent to the light absorbing layer, the light absorbing layer generates heat by laser light irradiation, The heat-induced decomposition or alteration of the organic material is induced, and the write-once type optical recording medium that performs recording at the recording / reproducing wavelength, or the light-absorbing layer generates heat by irradiating a laser beam having a Gaussian distribution, and this heat causes the heat-receiving layer A write-once type optical recording medium is provided in which recording is performed by deforming such that the amount of the dye layer material in the portion corresponding to the central portion of the Gaussian distribution is smaller than that in the outer peripheral portion.
[0017]
The optical recording medium of the present invention is a recording layer made of an organic material which has conventionally been a heat generating layer and which has functioned as a modulation degree generating layer due to a change in refractive index (real part of complex refractive index) caused by decomposition and alteration. And a heat generating layer and a heat receiving layer (modulation degree generating layer).
In a conventional write-once optical recording medium, the absorption coefficient at the recording / reproducing wavelength is reduced due to the decomposition and alteration of the organic material, and the degree of modulation is generated by utilizing the large change in the refractive index.
However, in the write-once optical recording medium of the present invention, the heat generating layer and the heat receiving layer are separated as described above, the area larger than the spot of the heat receiving layer is modified, and the medium has a Gaussian distribution. And recording, the modulation amount is generated by reducing the amount of the dye layer material in the portion corresponding to the central region of the Gaussian distribution from the outer peripheral portion.
Therefore, there is no restriction on the refractive index of the organic material used, which is required in the conventional recording layer, and the heat receiving layer does not need to have a light absorbing ability for the recording / reproducing wavelength. This eliminates the conventional strict restrictions on the optical constants of the organic materials used. Therefore, according to the present invention, various organic materials can be used even when a blue laser, particularly a blue semiconductor laser currently in practical use, is used, and the range of material selection is greatly expanded. However, it goes without saying that the principle of the present invention is not limited to the one using a blue laser.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
An optical information recording medium according to the present invention will be described with reference to FIGS. FIG. 1 is an enlarged sectional view of a main part of an optical information recording medium according to the present invention, and FIG. 2 is a plan view of the optical information recording medium of the present invention.
As is clear from these figures, the optical information recording medium of the present invention comprises a transparent substrate (1) having a pre-format pattern (2) formed on one side thereof in fine irregularities, a light absorbing layer (3), A heat-receiving layer (4) applied on the light-absorbing layer (3), a reflective layer (5) laminated on the heat-receiving layer (4), and a coating covering the reflective layer (5). It is composed of a protective layer (10).
As the transparent substrate (1), for example, a transparent resin material such as polycarbonate, polymethyl methacrylate, polymethyl pentene, epoxy, or the like is formed into a desired shape, and a desired preformat pattern is transferred to one surface of the transparent resin material. Any known transparent substrate can be used, such as a transparent resin layer having a desired preformat pattern transferred onto one surface of a transparent ceramic plate such as glass formed on the substrate.
As shown in FIG. 2, a transparent substrate (1) constituting a disc-shaped optical information recording medium (hereinafter, referred to as an optical disc) is formed in a disc shape having a center hole (1a) in the center. The method for producing the transparent substrate (1) is well-known and is not the gist of the present invention, so that the description is omitted.
[0019]
The preformat pattern (2) is configured to include at least a beam guide for causing a recording / reproducing laser beam to follow a recording track. In the example of FIGS. 1 and 2, the beam guide portion has a spirally or concentrically formed guide groove (2 a) concentric with the center hole (1 a), and extends along the guide groove (2 a). Thus, pre-pits (2b) such as address pits and clock pits are formed. When the pre-pit (2b) is formed on the guide groove (2a) so as to be optically distinguishable, the guide groove (2a) and the pre-pit (2b) are formed as shown in FIG. Are formed at different depths. When the pre-pits (2b) are formed between adjacent guide grooves (2a), both can be formed at the same depth. In addition, instead of the guide groove (2a), a wobble pit can be formed along the recording track as the beam guide. Further, the pre-pits (2b) may be omitted, and may be formed only by the guide grooves.
[0020]
The light absorbing layer (3) is formed of a material that absorbs light energy and converts it into heat energy, or a heat mode recording material containing at least a part of such an ionic dye material.
Examples of the dye material capable of forming the light absorbing layer (3) include polymethine dyes, anthraquinone dyes, cyanine dyes, phthalocyanine dyes, naphthalocyanine dyes, xanthene dyes, triphenylmethane dyes, and pyrylium dyes. Dyes, azulene dyes, metal-containing azo dyes, azo dyes and the like can be mentioned. Among these, dicarbocyanine derivatives, phthalocyanine derivatives, naphthalocyanine derivatives, cyanine derivatives, and azo dye derivatives are particularly preferably used. Alternatively, a dye material to which various quencher such as an aminium dye is added can be used. Furthermore, one or two or more dye materials selected from the above dye material group dispersed in a resin may be used as a material for forming the light absorbing layer (3). Examples of the resin material capable of dispersing the coloring material include an acrylic resin, a vinyl resin, a phenol resin, a fluororesin, a silicone resin, a polyamide resin, and a cellulose resin.
[0021]
The light absorbing layer (3) is formed by spin-coating a solvent solution of a coloring material selected from the coloring material group exemplified above on the preformat pattern forming surface of the transparent substrate (1). Further, after filling the groove-shaped preformat pattern (2) with the dye material, the dye material attached to the land portion (2c) between the preformat patterns (2) is selectively removed, and the transparent substrate (1) is removed. Can be formed by exposing the surface of the preform pattern and filling a dye material only in the preformat pattern (2). In addition, as a solvent of the coloring material, an alcohol-based solvent, a cellosolve-based solvent, or the like can be used.
[0022]
Further, the object of the present invention can be achieved by containing a chelating material capable of taking a bidentate ligand shown below. For example, inorganic acids, dicarboxylic acids, oxycarboxylic acids, dioxy compounds, oxioximes, oxyaldehydes and derivatives, diketones and similar compounds, oxyquinones, troborones, N-oxide compounds, aminocarboxylic acids and similar compounds, hydroxylamine , Oxines, aldimines, oxioximes, oxyazo compounds, nitrosonaphthols, triazenes, piuretes, formazans and dithizones, biqualides, glyoximes, diamines and similar compounds, hydrazine derivatives, thioethers. Furthermore, derivatives having an imino group (imide, amide) can also be used.
[0023]
In addition to the above organic materials, phase change materials that can change the atomic arrangement and record information can also be used. Specifically, they are metals and alloys represented by ABC-Ge-Te.
Here, A is Cu, Ag, Au, Sc, Y, Ti, Zr, V, Nb, Cr, Mo, Mn, Fe, Ru, Co, Rh, Ni, Pd, Hf, Ta, W, Ir, Pt, Hg, B, C, N, P, O, S, Se, a lanthanide element, an actinide element, an alkaline earth metal element, an inert gas element, and the like. B represents at least one of a halogen element such as Tl and I and an alkali metal element such as Na.
C represents at least one element of Sb, Sn, As, Pb, Bi, Zn, Cd, Si, Al, Ga and In.
Further, a metal material used for the magneto-optical material, for example, the above-mentioned metal elements such as Tb, Fe, and Co can also be used as the recording layer.
[0024]
Further, Fe, Ti, Zr, Ta, Cr, Mo, W, Ni, Rh, Pd, Pt, Cu, Ag, Au, Zn, Al, In, Si, Ge, Te, Sn, Bi, Sb, Tl, And at least one substance selected from the group consisting of aromatic compounds, aliphatic compounds, amides, esters, amines, ureas, sulfur compounds, and hydroxy compounds. Or anthraquinone-based, dioxidine-based, triphenodithiazine-based, phenanthrene-based, cyanine-based, phthalocyanine-based, naphthalocyanine-based, merocyanine-based, pyrylium-based, xanthene-based, triphenylmethane-based, croconium-based, azo-based , Indigoid, methine, azulene, sulfide and methanedithiol Or at least one dye selected from the group consisting of dyes based on acrylate or at least 50% by weight of a polymer, wherein the polymer is a vinyl alcohol-based resin, a vinyl acetate-based resin, an acrylate-based resin. Resin, polyester-based resin, polyether-based resin, polystyrene-based resin, polyurethane-based resin, at least one selected from the group consisting of cellulose-based resin and fatty acid-based resin, or a metal material such as aluminum, silver, and copper; , SiN, AlN, SiC, ZnO₂And the like, and it is particularly preferable to use a metal or alloy mainly composed of silver.
When silver is the main component, the silver content is preferably 80 to 100 atomic%, particularly preferably 90 to 100%.
[0025]
The thickness of the light absorbing layer (3) is preferably from 5 to 200 nm.
If the film thickness is less than 5 nm, the absorptance decreases, and the conversion from light to heat becomes insufficient. On the other hand, if the film thickness is larger than 200 nm, the volume is too large, so that deformation and heat transmission are insufficient.
When SiC is selected, the film thickness is preferably 8 to 14 nm.
When Ag was selected, a film thickness of 10 to 40 nm was preferable.
Micropores may be present in this layer, some of which are of the open cell type that penetrates.
A material having high hardness and low thermal conductivity is suitable for the light absorbing layer. High hardness is necessary to suppress unnecessary spread of deformation of the substrate and the cover layer, and leads to a reduction in crosstalk. The low thermal conductivity is necessary for efficiently (at low recording power) deforming the interface between the light absorbing layer and the substrate, the light absorbing layer and the cover layer, or the interface between the light absorbing layer and the organic material layer. It is also necessary for efficiently decomposing the organic material (with low recording power).
From the above points, it is preferable to use ceramics as the light absorbing layer.
[0026]
In addition, in order to cause the interface deformation between the light absorbing layer and the substrate, the light absorbing layer and the cover layer, or the light absorbing layer and the organic material layer at a low recording power, the decomposition of the organic material occurs at a low recording power. For this purpose, it is preferable to use, as the light absorbing layer, a layer having a somewhat large absorption coefficient with respect to the recording wavelength.
As ceramics, Al₂O₃, MgO, BeO, ZrO₂, UO₂, ThO₂Oxides such as simple oxides, SiO₂, 2MgO ・ SiO₂, MgO / SiO₂, CaO ・ SiO₃, ZrO₂・ SiO₂, 3Al₂O₃・ 2SiO₂2MgO.2Al₂O₃・ 5SiO₂, Li₂O ・ Al₂O₃・ 4SiO₂Silicate-based oxides such as Al₂TiO₅, MgAl₂O₄, Ca₁₀(PO₄)₆(OH)₂, BaTiO₃, LiNbO₃Oxides such as PZT, PLZT, ferrite, etc., or Si₃N₄, Si₆-ZAlZOZN₈Nitride-based non-oxides such as -Z, AlN, BN, TiN, SiC, B₄Carbide-based non-oxide such as C, TiC, WC, LaB₆, TiB₂, ZrB₂Boride based non-oxides such as CdS, MoS₂Sulfide-based non-oxides such as MoSi₂For example, a silicide-based non-oxide such as amorphous carbon, graphite, and diamond can be used.
[0027]
On the other hand, the heat receiving layer needs to be more easily affected by heat than the light absorbing layer and easily deformed or optically changed. Examples of such materials include anthraquinone, dioxidine, triphenodithiazine, phenanthrene, cyanine, phthalocyanine, naphthalocyanine, merocyanine, pyrylium, xanthene, triphenylmethane, croconium, At least one dye selected from the group consisting of azo, indigoid, methine, azulene, sulfide, and methanedithiolate dyes; in addition to the at least one dye, a vinyl alcohol resin, a vinyl acetate resin And at least 50% by weight of at least one polymer selected from the group consisting of acrylate resins, polyester resins, polyether resins, polystyrene resins, polyurethane resins, cellulose resins and fatty acid resins. Material, but may be mentioned, as the dye material used, cyanine, phthalocyanine, naphthalocyanine, merocyanine, azo and formazan chelate-based dyes are preferred. When the light absorbing layer has pores, the solvent for forming the heat receiving layer (4) is not particularly limited as long as it forms a solution having a certain contact angle that does not enter the pores. For example, esters such as butyl acetate and cellosolve acetate; ketones such as methyl ethyl ketone, cyclohexanone and methyl isobutyl ketone; chlorinated hydrocarbons such as dichloromethane, 1,2-dichloroethane and chloroform; amides such as dimethylformamide; hydrocarbons such as cyclohexane; Ethers such as tetrahydrofuran, ethyl ether and dioxane; alcohols such as ethanol, n-propanol, isopropanol and n-butanol diacetone alcohol; fluorinated solvents such as 2,2,3,3-tetrafluoropropanol; ethylene glycol monomethyl ether; Examples thereof include glycol ethers such as ethylene glycol monoethyl ether and propylene glycol monomethyl ether.
[0028]
The above solvents can be used alone or in combination of two or more in consideration of the solubility of the dye to be used. Various additives such as an antioxidant, a UV absorber, a plasticizer, and a lubricant may be further added to the coating solution according to the purpose. Furthermore, in order to more effectively prevent the penetration into the micropores, after applying the coating solution for the heat receiving layer, the coating is dried or subjected to a crosslinking treatment, a crystallization treatment, etc., and the membrane is fixed early. Is preferred. As a specific means of the cross-linking treatment, the same means as in the case of the underlayer described later can be employed.
When forming the light absorbing layer or the heat receiving layer, a binder can be further used. Examples of the binder include natural organic high molecular substances such as gelatin, cellulose derivatives, dextran, rosin, and rubber; and hydrocarbon resins such as polyethylene, polypropylene, polystyrene, and polyisobutylene; polyvinyl chloride, polyvinylidene chloride, and polyvinyl chloride. Vinyl resins such as vinyl / polyvinyl acetate copolymers, acrylic resins such as polymethyl acrylate and polymethyl methacrylate, polyvinyl alcohol, chlorinated polyethylene, epoxy resins, butyral resins, rubber derivatives, phenol / formaldehyde resins, etc. Synthetic organic polymers such as precondensates of thermosetting resins can be mentioned. When a binder is used in combination as a material for the recording layer, the amount of the binder used is generally in the range of 0.01 to 50 times (mass ratio) the dye, preferably 0.1 time. It is in the range of up to 5 times (mass ratio). The concentration of the coating solution thus prepared is generally in the range of 0.01 to 10% by mass, preferably in the range of 0.1 to 5% by mass.
Examples of the application method include a spray method, a spin coating method, a dip method, a roll coating method, a blade coating method, a doctor roll method, and a screen printing method. The recording layer may be a single layer or a multilayer.
[0029]
As described above, the heat receiving layer (4) is more thermally affected than the light absorbing layer (3), and is deformed, deteriorated, or optically changed. The heat receiving layer (4) was irradiated with light exhibiting a Gaussian distribution, and as a result of recording, the amount of the dye layer material corresponding to the central part of the Gaussian distribution was smaller than that of the outer peripheral part.
[0030]
The types of deformation of other layers are shown below.
The case where the substrate (1) is raised as shown in FIG. 3, the case where it is not deformed as shown in FIG. 4 or changes temporarily and finally becomes a shape without deformation, as shown in FIG. 5. May collapse.
The light-absorbing layer (3) laminated on the substrate rises in the direction opposite to the substrate as shown in FIGS. 3 and 4, and collapses toward the substrate as shown in FIG. May swell like.
In addition, there are a case where the substrate also rises together with the rise of the light absorption layer as shown in FIG. 3 and a case where a cavity is formed between the substrate and the light absorption layer as shown in FIG.
[0031]
As shown in FIGS. 3 and 4, the deformation mode of the heat receiving layer (4) is as shown in FIGS. 3 and 4, when the upper and lower sides are concave as shown in FIG. 8, and as shown in FIG. When the substrate side changes to a concave shape, when a cavity is formed near the center of the heat receiving layer as shown in FIG. 6, when the upper and lower sides of the heat receiving layer change to the substrate side as shown in FIG. As shown in FIG. 9, the upper and lower portions of the heat receiving layer may change in a concave shape on the side opposite to the substrate.
[0032]
The deformation of the reflective layer (5) is shown in FIG. 12 when the upper and lower portions of the reflective layer are raised to the opposite side to the substrate as shown in FIG. As shown in FIG. 8, when the shape changes to a convex shape on the substrate side as described above, it may be depressed on the substrate side. The shapes of the substrate, the light absorbing layer, the heat receiving layer, and the reflective layer can be independently combined. At that time, when the deformation is in the opposite direction on each floor, a cavity is formed at the interface as shown in FIGS.
[0033]
Next, deterioration of components contained in the heat receiving layer (4) will be described.
For example, when a dye material is used, the dye material receives heat from the light absorbing layer (3), and part or all of the dye material is decomposed, melted, or sublimated. As a result, the deteriorated portion adheres to the reflective layer (5), and when peeled off by the heat receiving layer (4), the deteriorated portion is preferentially applied to the reflective layer (5) and the non-transformed portion is preferentially applied to the light absorbing layer (3). Adhered and peeled.
In the present invention, since the interface between the reflective layer and the heat receiving layer plays a role in reflection, it is important that the dye material whose surface of the reflective layer is modified adheres to control the reflected light from that portion.
Conversely, the adhesion changes due to the alteration, and when the non-altered portion adheres to the reflective layer and peels off with the heat receiving layer, the non-altered portion adheres to the reflective layer preferentially, and the altered portion adheres to the light absorbing layer with priority. It may be done. In this case, the reflectivity may increase after recording.
In addition, it is necessary to determine the recording power, the recording pulse length, and the type while confirming the state of deterioration. The solubility of the pigment material in the altered part changes because its structure is destroyed. If the change in solubility is different from the non-degraded part, the range of degeneration can be confirmed.
For example, when the dye material is decomposed to lower molecular weight, and the solubility increases, that is, there is no problem even if it changes in the direction in which it easily dissolves, but in the present invention, the solubility of the altered part decreases, that is, in the direction in which it is difficult to dissolve. Deterioration was favorable because it was a direction of a decrease in reflectance, which is a change in optical properties due to melting, decomposition, and sublimation of the dye.
Dye materials having reduced solubility include, for example, azo dyes and formazan chelate dyes, and dye materials having increased solubility include phthalocyanine dyes and cyanine dyes.
[0034]
To confirm the solubility, the solvent is directly permeated into the altered part and the non-altered part, and the solubility is compared.
Examples of the solvent used include esters such as butyl acetate and cellosolve acetate; ketones such as methyl ethyl ketone, cyclohexanone and methyl isobutyl ketone; chlorinated hydrocarbons such as dichloromethane, 1,2-dichloroethane and chloroform; amides such as dimethylformamide; cyclohexane Hydrocarbons such as tetrahydrofuran, ethyl ether and dioxane; alcohols such as ethanol, n-propanol, isopropanol and n-butanol diacetone alcohol; fluorinated solvents such as 2,2,3,3-tetrafluoropropanol; Glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, etc. Can. The above solvents can be used alone or in combination of two or more in consideration of the solubility of the dye to be used.
[0035]
As a result of recording by irradiating light showing a Gaussian distribution and recording, it is necessary that the alteration range extends to the inside and outside of the recording mark area where the light intensity is increased for recording.
The reason is that even when the spot system changes due to the inclination of the substrate or the like at the time of recording / reproducing, since the recording outside the spot system is performed, the signal is not changed and the signal is hardly affected by the inclination or the like.
Here, the recording mark area is a spot represented by r = λ / 2NA × K (where λ represents the wavelength used for recording, NA represents the aperture ratio of the lens, and K = 0.6 to 1.22). Is irradiated, and the spot is moved. In the case of r = λ / 2NA × 0.6, the signal is recorded with good jitter and little jitter. Here, λ represents the wavelength used for recording, and NA represents the aperture ratio of the lens.
Further, even when r = λ / 2NA, good recording with little jitter can be achieved by controlling the thickness of the heat receiving layer.
Further, in the case of r = λ / 2NA × 1.22, the deterioration range outside the recording mark area is widened, a strong contrast is obtained, and the effect of the inclination of the disk or the like is reduced.
In the present invention, K is preferably 0.6 to 1.22.
[0036]
In the present invention, in particular, the change amount of the apparent optical characteristics of the unrecorded part in the recording area, that is, the unrecorded part after recording, is changed to the value of the optical property of the unrecorded part in the unrecorded area, that is, the unrecorded part before recording. On the other hand, it is preferable to set the relative value within ± 50%. Here, the apparent optical characteristics will be described. When the disc is stopped, for example, when a recording area is formed such as unrecorded-recorded-unrecorded, the reflected light amount is such that only the recorded portion is unrecorded. It is somewhat lower than the part. On the other hand, when the disk is rotating at a certain linear velocity, the reflected light amount does not decrease only in the recorded portion of the above-mentioned unrecorded-recorded-unrecorded state. Before the recording, the next recorded portion comes, so that the reflectance of the unrecorded portion also decreases. The apparent change in optical characteristics means that the reflectivity of an unrecorded portion apparently decreases due to such a phenomenon.
In the present invention, as described above, the amount of change in the apparent optical characteristics of the unrecorded area in the unrecorded area is within ± 50% relative to the value of the optical property of the unrecorded area in the unrecorded area. However, if the difference is within ± 50%, the reflectance of the unrecorded portion of the recording region does not change due to recording, and the difference between the reflectances of the unrecorded portion of the recording region and the unrecorded portion of the unrecorded region becomes The optical pickup can stably follow the track even when reproducing and recording an unrecorded area continuously from the recorded area, and the occurrence of a track off or the like can be prevented. The amount of change in the optical characteristics can be controlled by controlling the size of the spot system.
[0037]
When the reflectance of the unrecorded portion is set to 100, the reflectance of the recorded portion can be arbitrarily adjusted within the range of 10 to 250 by the shape of the main recorded portion, the deterioration of the recorded portion, and the method of checking the deterioration.
The relationship between the reflectance and each factor is based on the following relational expression.
Assuming that the amplitude reflectance when the light travels from the medium 1 to the medium 2 is γ12 and the amplitude transmittance is t12, the amplitude reflectance γ12 and the amplitude transmittance t12 at the time of normal incidence are the refractive index n1 of the medium 1 and the medium 2. , N2 using the following equation.
[0038]
(Equation 1)

[0039]
(Equation 2)

The energy reflectance R is represented by the following equation using the amplitude reflectance γ.
[0040]
(Equation 3)
R = | γ | 2 (3)
That is, when the incident wave is a0cosθ and the combined wave of the reflected waves is a′cos (θ + Δ), the energy reflectance R is represented by the following equation.
[0041]
(Equation 4)

By utilizing this, it is possible to calculate a suitable range of each factor, selection of a material, and recording conditions.
[0042]
When the thickness of the heat receiving layer (4) is less than 5 nm, heat absorption is not sufficient, and deformation and change are insufficient. On the other hand, when the film thickness is larger than 200 nm, there is a problem because the volume is large and deformation is suppressed, and there is a portion which cannot be changed optically due to thermal influence.
In the present invention, the heat-receiving layer is formed by dissolving the above-described material in an organic solvent and spin-coating the material on the light-absorbing layer. At this time, the organic solvent needs to be capable of easily dissolving the above-mentioned material, and when the solution has pores in the light absorbing layer, it needs to have a certain contact angle that does not enter the pores.
[0043]
Here, the constant contact angle that does not enter the pore means that the required surface tension varies depending on the size of the pore, so that the value of the surface tension cannot be quantified. 225 μm in a portion thinner than the average film thickness by 2% or more²Is the upper limit, and if it is beyond this range, problems such as tracking accuracy and error correction become impossible. Therefore, even if the solution permeates the pore, if the permeation does not spread beyond the above range, it is determined that the solution has a certain contact angle that does not enter the pore.
[0044]
The material used for the reflection layer (5) is not particularly limited, but a metal material such as aluminum, silver, and copper or an alloy material containing these as a main component can be used. In particular, it is preferable to use a metal or alloy mainly composed of gold.
When it is mainly composed of silver, the silver content is preferably 80 to 100 atomic%, particularly preferably 90 to 100%.
Of these reflective layer materials, aluminum can be used because it is inexpensive and has a proven track record of being used in compact discs. When a metal material or an alloy material is used as the reflective layer material, the reflective layer can be formed by a vacuum film forming method such as sputtering or vacuum deposition. In this case, the degree of vacuum in the vacuum chamber is changed (for example, 10^-5A technique in which sputtering is performed to form films having different densities or crystallization states to increase the reflectance of the metal reflective layer can also be applied.
[0045]
The protective layer (10) can be formed using an inorganic material such as SiO, SiN, or AlN, or an organic material such as a photocurable resin. The inorganic protective layer can be formed by a vacuum film forming method, and the organic protective layer is a photocurable resin film (for example, SD1700, SD318, SD301 of Dainippon Ink and Chemicals, Inc.) on the reflective layer (5). ) Can be formed by irradiating resin curing light after spin coating.
When a lens with a high NA is used to increase the density, the protective layer needs to be light-transmissive. For example, when the NA is increased, it is necessary to reduce the thickness of a portion through which the reproduction light is transmitted. This is due to an angle (a so-called tilt angle, which is proportional to the square of the product of the reciprocal of the wavelength of the light source and the numerical aperture of the objective lens) in which the disk surface deviates from the perpendicular to the optical axis of the optical pickup with the increase in NA. This is because the allowable amount of the generated aberration is small, and the tilt angle is easily affected by the aberration due to the thickness of the substrate.
Therefore, the influence of the aberration on the tilt angle is made as small as possible by reducing the thickness of the substrate.
[0046]
Therefore, for example, irregularities are formed on a substrate to form a recording layer, a reflective layer is provided thereon, and a light-transmitting protective layer, which is a thin film that transmits light, is provided thereon. An optical recording medium that reproduces information on a recording layer by irradiating light, a reflective layer is provided on a substrate, and a heat receiving layer and a light absorbing layer are formed thereon to form a recording layer. There has been proposed an optical recording medium in which a protective layer having transparency is provided, and reproducing information is irradiated from the protective layer side to reproduce information on the recording layer. With this configuration, it is possible to cope with an increase in the NA of the objective lens by reducing the thickness of the cover layer. That is, by providing a thin cover layer and performing recording / reproduction from the cover layer side, it is possible to further increase the recording density. Note that such a protective layer is generally formed of a polycarbonate sheet or an ultraviolet curable resin. The thickness is preferably 0.1 mm or less.
[0047]
In the present invention, the substrate (1) is made of a material that maintains transparency with respect to a laser, has an excellent impact strength, and easily expands, deforms or deteriorates at a temperature of 80 to 200 ° C. Materials satisfying such characteristics include polycarbonate, polymethyl methacrylate, epoxy resin, polyester, and amorphous polyolefin, and the glass transition temperature (Tg) is desirably 100 to 200 ° C. In addition, a pregroove for guiding incident laser light during recording or reproduction is formed on the substrate surface, and its depth is desirably 10 to 200 nm. When the depth of the pre-groove is less than 10 nm, the reflectivity is greatly increased due to the expansion of the substrate after recording, and the recording signal has a lot of noise. When the depth exceeds 200 nm, the pre-groove is deep in the heat receiving layer. Therefore, it is difficult to obtain a uniform film.
[0048]
The thermal conductivity of the light absorbing layer (3) is desirably 10 (W / cm · ° C.) or less. If it exceeds 10 (W / cm · ° C.), the heat generated from the metal recording film by the laser is rapidly conducted to the surroundings, and the thin film itself is hard to be heated to a predetermined temperature or more. Since the pits are large, there is a possibility that adjacent tracks may be deformed.
Further, the coefficient of linear expansion of the light absorbing layer (3) is 3 × 10^-7/ ° C or higher. If it is less than the above range, cracks occur in the metal recording film due to expansion of the substrate during recording, and thus a uniform recording signal cannot be obtained.
The solvent used for forming the heat receiving layer needs to have a solubility of 5 mg / 1 ml or more.
[0049]
On the other hand, it is also possible to add a super-resolution technique to the light absorbing layer. Usually, the reproduction limit of an optical disk is represented by λ / 2NA (where λ is the wavelength, and NA is the sine of the accuracy of focusing the light).
In order to realize a resolution exceeding this limit, the following super-resolution technology is applied.
The intensity distribution I of the reproduction beam obtained by condensing the laser light on the medium by the objective lens is expressed by the following equation.
[0050]
(Equation 5)
I = I₀* Exp (-2 (r / r₀)²)
(Where I₀Is the intensity at the center of the laser beam, and the intensity of the laser beam is 1 / e²Is the radius r₀And )
When the recording medium is heated by the reproducing beam having the intensity distribution of Gaussian distribution, the temperature distribution of the portion irradiated with the beam also becomes similar to the Gaussian distribution.
By setting a high temperature portion near the center of the beam as a reproduction region and a low temperature portion around the periphery as a portion not involved in recording / reproduction, the effective beam spot diameter is reduced and the resolution is improved.
In the Gaussian distribution, the temperature is about 0.6 times the center temperature, that is, the radius r₀The slope becomes steep at / 2. When this portion is adjusted, stable recording and reproduction can be performed.
[0051]
Further, the heat receiving layer uses a thermochromic dye, and recording / reproducing can be performed by utilizing an optical change of the heat absorbing layer such as a change of an absorption coefficient.
As the thermochromic dye to be used, spiropyran, fluoran, bianthrone, and triarylimidazole can be used.
[0052]
Further, the light absorbing layer absorbs light, converts the light into electric energy, and can perform recording on the heat absorbing layer by electrochemical redox.
In that case, the light absorption layer can be made of Ge, Si, GaAs, Gap, CdSe, CdS, ZnO, SnO, TiO, SiC, or the like.
In addition, a thionin dye, an indigo dye, tungsten oxide, merocyanine, phthalocyanine, perylenetetracarboxylic acid, rhodamine, quinacridone, polyacetylene, poly (3-methylthiophene), and poly (N-methylpyrrole) can be used for the heat receiving layer. It is.
[0053]
FIG. 17 is a diagram for explaining the combined light of the reflected light at each interface of the optical information recording medium of the present invention. Each signal in the figure is as follows.
1: substrate made of polycarbonate
4: Recording layer made of organic dye
3: Thin layer made of SiC
Gap between 1 and 3: air (gap)
5: Ag reflection layer
n0: refractive index of air (n0 = 1)
n1: refractive index of PC (n1 = 1.6)
n2: Refractive index of SiC (n2 = 2.8)
n3: refractive index of dye (n3 = 1.4)
n4: refractive index of Ag (n4 = 0.1)
d1: thickness of cavity
d2: film thickness of SiC
d3: thickness of dye
d4: Ag film thickness
A1: Light reflected at the interface between PC and cavity
A2: Light reflected at the interface between the cavity and SiC
A3: Light reflected at the interface between SiC and dye
A4: Light reflected at the interface between dye and Ag
A5: Light reflected at the interface between Ag and PC
The reflected light A1 to A5 at each interface can be represented by the following equation.
[0054]
(Equation 6)
A1 = γ10 cos θ (1)
A2 = t10γ02t01cos (θ + 4πn0d1 / λ) (2)
A3 = t10t02γ23t20t01cos (θ + 4π (n0d1 + n2d2) / λ) (3)
A4 = t10t02t23γ34t32t20t01cos (θ + 4π (n0d1 + n2d2 + n3d3) / λ) (4)
A5 = t10t02t23t41γ41t14t32t20t01cos (θ + 4π (n0d1 + n2d2 + n3d3 + n4d4) / λ) (5)
Therefore, the light (A1 + A2 + A3 + A4 + A5) = a′cos (θ + Δ) obtained by combining the reflected light A1 to A5 at each interface is solved, and a ′ is expressed by γ, t, n, d, λ, and the respective values are substituted. The result is the energy reflectance R (because a0 = 1).
Here, the calculation of the central part of the recording is shown as a representative example, but in actuality, it is necessary to slightly change the calculation location and consider the influence of the shape of each layer.
In addition, although the influence of alteration is not taken into account here, this effect needs to be considered together with deformation.
Further, in the above equation, multiple reflection between the respective layers is not taken into consideration, but in practice, it is necessary to take appropriate consideration.
[0055]
Specifically, the contents are as shown in FIG. Here, for the sake of simplicity, considering a three-layer structure, the complex amplitude of the reflected wave C is once reflected light C₁, Twice reflected light C₂, Reflected light C three times₃,….
Therefore, the sum C of the complex amplitudes of the reflected wave is represented by a geometric series.
[0056]
(Equation 7)
C = ｛r + tt'r'e^jδ(1 + r '²e^jδ+ R '⁴e^2jδ+…)｝ A₀
[0057]
Hereinafter, the information recording medium of the present invention and its manufacturing method will be specifically described with reference to FIGS.
FIG. 18 is an enlarged sectional view of a main part showing an example of the optical information recording medium according to the present invention. As is clear from this figure, the optical information recording medium of the present example has an underlayer (6) formed on the preformat pattern forming surface of the transparent substrate (1). The underlayer (6) is provided as an improvement in adhesion between the transparent substrate (1) and the light absorbing layer (3), an improvement in recording sensitivity, protection of the light absorbing layer (3), and a heat absorbing layer. For example, it is formed of a hydrophilic resin such as polyvinyl alcohol, polyethylene oxide, polyacrylic acid, sodium polystyrene sulfonate, polyvinyl pyrrolidone, polymethacrylic acid, polypropylene glycol, methyl cellulose, polyvinyl nitrate, and nitrocellulose. The underlayer (6) can be formed by spin-coating an aqueous solution of a hydrophilic resin on the preformat pattern forming surface (2) of the transparent substrate (1).
Since the underlayer (6) is made of a hydrophilic resin, it has poor water resistance (moisture resistance, moisture permeability) and heat resistance. Therefore, it is preferable to improve the water resistance and heat resistance by subjecting the underlayer (6) to a crosslinking treatment or a crystallization treatment. Specifically, after a crosslinking agent is added to an aqueous solution of a hydrophilic resin to form a base layer (6), a crosslinking reaction by light irradiation or a crosslinking reaction by heating is caused, or no crosslinking agent is added. The underlayer (6) is crystallized by heat treatment (for example, when polyvinyl alcohol (PVA) is used as the hydrophilic resin, PVA is modified into PVA).
[0058]
Comparing the cross-linking treatment with the crystallization treatment, the cross-linking treatment is more preferable than the crystallization treatment because the transparent substrate (1) is not adversely affected by heating and has excellent workability. Hereinafter, specific examples of the crosslinking reaction will be described. At the time of implementation, any means can be adopted as necessary from these crosslinking reactions.
(I) A method in which ammonium dichromate is added as a cross-linking agent to treat the surface of the dye and, at the same time, irradiate reaction light after film formation to cause a cross-linking reaction in the underlayer.
(II) A method of adding, for example, copper, boron, aluminum, titanium, zirconium, tin, vanadium, chromium, etc. as an inorganic crosslinking agent.
(III) A method of acetalization using an aldehyde.
(IV) A method of converting a hydroxyl group into an aldehyde.
(V) A method of adding an activated vinyl compound.
(VI) A method of adding an epoxy compound to form an ether.
(VII) A method in which a dicarboxylic acid reaction is caused under an acid catalysis.
(VIII) A method of adding succinic acid and sulfuric acid.
(IV) A method of adding triethylene glycol and methyl acrylate.
(X) A method of blending a polyacrylic acid and a methylvinylethermaleic acid copolymer.
[0059]
The underlayer (6) contains, in the preformat pattern (2), a material that absorbs light energy and converts it into heat energy, or a heat mode recording material containing at least a part of such an ionic dye material. It is formed by filling.
Examples of the dye material that can form the underlayer (6) include polymethine dyes, anthraquinone dyes, cyanine dyes, phthalocyanine dyes, naphthalocyanine dyes, xanthene dyes, triphenylmethane dyes, pyrylium dyes, Examples thereof include azulene-based dyes, metal-containing azo dyes, and azo dyes. Among these, dicarbocyanine derivatives, phthalocyanine derivatives, naphthalocyanine derivatives, cyanine derivatives, and azo dye derivatives are particularly preferably used. Alternatively, a dye material to which various quencher such as an aminium dye is added can be used. Further, one or two or more kinds of dye materials selected from the above-described dye material group dispersed in a resin can be used as a material for forming the underlayer (6). Examples of the resin material capable of dispersing the coloring material include an acrylic resin, a vinyl resin, a phenol resin, a fluororesin, a silicone resin, a polyamide resin, and a cellulose resin.
[0060]
The underlayer (6) is formed by spin-coating a solvent solution of a coloring material selected from the coloring material group exemplified above on the preformat pattern forming surface of the transparent substrate (1). Further, after filling the groove-shaped preformat pattern (2) with the dye material, the dye material attached to the land portion (2c) between the preformat patterns (2) is selectively removed, and the transparent substrate (1) is removed. Can be formed by exposing the surface of the preform pattern and filling a dye material only in the preformat pattern (2). In addition, as a solvent of the coloring material, an alcohol-based solvent, a cellosolve-based solvent, or the like can be used.
[0061]
Further, the object of the present invention can be achieved by containing a chelating material capable of taking a bidentate ligand shown below. For example, inorganic acids, dicarboxylic acids, oxycarboxylic acids, dioxy compounds, oxioximes, oxyaldehydes and derivatives, diketones and similar compounds, oxyquinones, troborones, N-oxide compounds, aminocarboxylic acids and similar compounds, hydroxylamine , Oxines, aldimines, oxioximes, oxyazo compounds, nitrosonaphthols, triazenes, piuretes, formazans and dithizones, biqualides, glyoximes, diamines and similar compounds, hydrazine derivatives, thioethers. Furthermore, derivatives having an imino group (imide, amide) can also be used.
[0062]
In addition to the above organic materials, phase change materials that can change the atomic arrangement and record information can also be used.
Specifically, they are metals and alloys represented by ABC-Ge-Te.
Here, A is Cu, Ag, Au, Sc, Y, Ti, Zr, V, Nb, Cr, Mo, Mn, Fe, Ru, Co, Rh, Ni, Pd, Hf, Ta, W, Ir, Pt, It represents at least one of Hg, B, C, N, P, O, S, Se, a lanthanide element, an actinide element, an alkaline earth metal element, an inert gas element, and the like.
B represents at least one of a halogen element such as Tl and I and an alkali metal element such as Na.
C represents at least one element of Sb, Sn, As, Pb, Bi, Zn, Cd, Si, Al, Ga and In.
Further, a metal material used for the magneto-optical material, for example, the above-mentioned metal elements such as Tb, Fe, and Co can also be used as the recording layer.
[0063]
Further, Fe, Ti, Zr, Ta, Cr, Mo, W, Ni, Rh, Pd, Pt, Cu, Ag, Au, Zn, Al, In, Si, Ge, Te, Sn, Bi, Sb, Tl, And at least one substance selected from the group consisting of aromatic compounds, aliphatic compounds, amides, esters, amines, ureas, sulfur compounds, and hydroxy compounds. Or anthraquinone-based, dioxidine-based, triphenodithiazine-based, phenanthrene-based, cyanine-based, phthalocyanine-based, naphthalocyanine-based, merocyanine-based, pyrylium-based, xanthene-based, triphenylmethane-based, croconium-based, azo-based , Indigoid, methine, azulene, sulfide and methanedithiol Or at least one dye selected from the group consisting of dyes based on acrylate or at least 50% by weight of a polymer, wherein the polymer is a vinyl alcohol-based resin, a vinyl acetate-based resin, an acrylate-based resin. Resin, polyester-based resin, polyether-based resin, polystyrene-based resin, polyurethane-based resin, at least one selected from the group consisting of cellulose-based resin and fatty acid-based resin, or a metal material such as aluminum, silver, and copper; , SiN, AlN, SiC, ZnO₂And the like, and it is particularly preferable to use a metal or alloy mainly composed of gold.
When it is mainly composed of silver, the silver content is preferably 80 to 100 atomic%, particularly preferably 90 to 100%.
[0064]
The thickness of the underlayer (6) is preferably from 5 to 200 nm.
If the film thickness is smaller than 5 nm, the film formation is not stable. On the other hand, when the film thickness is larger than 200 nm, the volume is too large, so that deformation, heat transmission, and hole formation become insufficient.
When SiC is selected, the film thickness is preferably 8 to 14 nm.
When Ag was selected, a film thickness of 10 to 40 nm was preferable.
In this layer there are micropores, in which there is a penetrating open cell type.
[0065]
FIG. 19 is an enlarged sectional view of a main part showing another example of the optical information recording medium according to the present invention. As is apparent from this figure, the optical information recording medium of the present invention is laminated between the light absorbing layer (3) and the heat receiving layer (4) via the intermediate layer (7). The intermediate layer (7) is provided for improving the adhesion between the information recording portion (3) and the reflective layer (4), improving the recording sensitivity, and protecting the information recording portion (3). The same kind of hydrophilic resin as the underlayer (6) or the material of the light absorbing layer (3) can be used. When a hydrophilic resin is selected as the material of the intermediate layer (7), the aqueous solution can be spin-coated on the information recording section (3). Also for the intermediate layer (7), it is preferable to subject the spin-coated intermediate layer (7) to a crosslinking treatment or a crystallization treatment in order to improve water resistance and heat resistance. The cross-linking treatment and the crystallization treatment can be performed in the same manner as the base film.
[0066]
FIG. 20 is an example of a flowchart for manufacturing a disk according to the present invention.
Hereinafter, the procedure will be specifically described.
S1: Polish and wash the glass disk.
S2: Silane coat
S3: A photoresist is spin-coated on the glass disk to form a resist layer having a predetermined thickness.
S4: Prebake is performed to blow off the solvent.
S5: The resist layer is irradiated with a laser through a condenser lens (cutting).
S6: The exposed glass disk is developed.
S7: The resist is heated above Tg to shape the groove shape (first bake).
S8: Baking is performed to solidify the pattern (second baking).
S9: evaporation, plating
S10: A metal film is formed on the uneven surface of the glass disk, and the metal film is peeled off to form a stamper.
S11: Injection molding is performed using a stamper to form a replica layer having a predetermined thickness.
S12: A hard coat layer is formed on one side of the transparent substrate by a spin coating method.
S13: An underlayer is formed on one surface of the transparent substrate by spin coating or sputtering as necessary.
S14: A light absorption layer is formed on the upper surface of the underlayer by spin coating or sputtering.
S15: forming a heat receiving layer on the light absorbing layer.
S16: forming a reflective layer on the heat receiving layer.
S17: A case where a protective layer and other layers are laminated as necessary and used as a single plate.
S18: A protective layer and other layers are laminated as necessary, and the respective disks are laminated to form a double-sided disk.
S19: This disc is stored in the cartridge.
S20: The characteristics are evaluated.
Regarding this flowchart, S7 and S8 can be performed simultaneously. The shaping of the groove shape can be arbitrarily selected from a heating temperature of 90 degrees or more and 180 degrees or less and a time of 5 to 90 minutes.
In this description, a disk-shaped recording medium is taken as an example, but the present invention is not limited to this. For example, a card-shaped, stick-shaped or tape-shaped information recording medium may be used. Of course, it can be applied.
[0067]
【Example】
Hereinafter, the present invention will be specifically described based on examples.
An SiC film is formed on a polycarbonate substrate having a preformat pattern shown in FIGS. 1 and 2 by a sputtering method, and an organic material layer made of a dye mixture represented by the following (Chemical Formula 1) is further spin-coated thereon. A heat absorbing layer was formed by a method (average film thickness: 100 nm).
A silver film having a thickness of 100 nm was formed on the heat absorbing layer by a sputtering method to form a reflective layer. A protective layer was formed by laminating SD1700 (thermal conductivity: 1.0 or less) of Dainippon Ink and Chemicals, Ltd. with a film thickness of 5 μm on the reflective layer. Further, a UV-curable ink layer was provided on the protective layer. Specifically, DICUV ink (Dainippon Ink and Chemicals, Inc.) was laminated in a range of 0.1 g to 7.0 g.
Recording was performed on the optical recording medium under the following conditions using an optical disk evaluation device DDU-1000 (wavelength: 405 nm, NA: 0.65) manufactured by Pulstec Industrial Co., Ltd.
As a result, the short mark = 0.3 μm, the modulation degree is 30%, the long mark = 1.0 μm, the modulation degree is 60%. The modulation degree is sufficiently large for both the short mark and the long mark, and a very clear signal can be obtained. Was.
[0068]
Embedded image

[0069]
(Recording conditions)
Recording linear velocity: 6.0 (m / s)
Recording strategy: Basic \ strategy \ Ttop-Tmp =
1.40-0.75 (T)
Recording power: 11.0 (mw)
Recording pattern: 3T, 4T, 5T, 8T, 14T single period signal
[0070]
The above recording conditions were determined while observing the recording portion of the information recording medium. In the method, first, the heat receiving layer is peeled off. In the present embodiment, the color material of the altered portion preferentially adhered to the reflective layer, and the non-altered portion preferentially adhered to the light absorbing layer side.
Further, ethanol was dropped on the peeled reflecting layer and light absorbing layer to measure the range of deterioration, and the results were reflected in the recording conditions, and the above conditions were found.
[0071]
FIG. 15 shows a case where the cross section of the recording section is recorded on a land, and FIG. 16 shows a case where it is recorded on a groove. As can be seen from FIGS. 15 and 16, in this example, in the heat-receiving layer, the amount of dye at the center of the recording spot was reduced, and the heat-receiving layer was altered to the outside of the recording spot diameter. The recording spot diameter r used here is a range represented by r = λ / 2NA × K (where K = 0.6 to 1.22).
Further, the light absorbing layer became convex on the opposite side to the substrate, and the substrate deformed concavely.
[0072]
In this medium, the light absorbing layer has 10 or more pores of φ = 2 μm, four pores of φ = 5 μm, and one pore of φ = 10 μm. Due to this effect, the average film thickness is smaller than the average film thickness in the range of 225 μm 2. Although there was a portion that was thinner than 2% of the film thickness, the error was corrected by the player, and good reproduction was possible.
In addition, even in a portion where no pore was present, a portion having an island thickness of 2% or more of the average film thickness was confirmed. This portion is not an open cell but a closed cell.
Note that the complex refractive index of (formula 1) at 405 nm is 1.485-i 0.069.
[0073]
According to this example, it was confirmed that the layer configuration and the recording principle of the optical recording medium of the present invention were very effective for realizing a write-once optical recording medium made of an organic material corresponding to a blue laser wavelength. Further, it was confirmed that the layer configuration and the recording principle of the optical recording medium of the present invention were very effective for realizing a write-once optical recording medium capable of securing a high degree of modulation corresponding to a blue laser wavelength.
[0074]
【The invention's effect】
As apparent from the detailed and specific description, the invention according to claim 1 has information having a layer structure in which a heat-receiving layer containing a dye material is laminated on a light-absorbing layer so as to have a thickness of 200 nm or less. According to a recording medium, the medium is irradiated with light exhibiting a Gaussian distribution, and as a result of the recording, the heat receiving layer is degraded inside and outside the recording mark area where the light intensity is increased for recording. By doing so, a large contrast can be obtained, and even when the substrate is tilted, there is no change in the signal, and the signal is hardly affected by the tilt and the like.
The invention according to claim 2 relates to an information recording medium having a layer structure in which a heat receiving layer containing a dye material is laminated on a light absorbing layer so as to have a thickness of 200 nm or less. As a result of recording by irradiating light indicating that the component amount in the heat receiving layer in the portion corresponding to the central portion of the Gaussian distribution is smaller than that in the outer peripheral portion, a large contrast can be obtained and good recording can be performed. can do. According to a third aspect of the present invention, in the information recording medium according to the first or second aspect, the dye material is selected from the group consisting of cyanine, phthalocyanine, naphthalocyanine, merocyanine, azo, and formazan chelate. Is limited to at least one dye, and a higher contrast can be obtained. According to the fourth aspect of the present invention, at least the heat-receiving layer is deformed by irradiating light exhibiting a Gaussian distribution, and at least the heat-receiving layer is deformed, whereby a higher contrast can be obtained. According to the fifth aspect of the present invention, a high contrast can be obtained because the heat receiving layer has an increased light intensity for recording, that is, the inside of the recording mark area and the outside of the recording mark area are altered, so that good recording is possible. be able to. According to a sixth aspect of the present invention, the reflective layer is laminated on the heat-receiving layer, and the interface between the reflective layer and the heat-receiving layer is used as a carrier for reflection. The peeled dye material of the heat receiving layer adheres to the interface of the reflective layer, which is important in controlling the reflected light from the interface. As a result, a large contrast can be obtained, and good recording can be performed.
According to a seventh aspect of the present invention, the recording mark area is obtained by irradiating and moving a spot of r = λ / NA × 0.8 (where λ is the wavelength used for recording and NA is the aperture ratio of the lens). Since it is within the range, it is possible to perform good recording with little influence on an adjacent track and small jitter. According to the invention of claim 8, the adhesiveness is changed due to the deterioration of the heat receiving layer, and the heat-receiving layer is peeled off. This means that the deterioration is promoted until this occurs, whereby a large contrast can be obtained.
According to the ninth aspect of the present invention, the heat receiving layer is altered by the decomposition, sublimation, and melting of the material, and the dissolution characteristics are used as a guide for observing the change in the optical properties. By inducing alteration, a large contrast can be obtained.
According to a tenth aspect of the present invention, for example, the amount of change in apparent optical characteristics of an unrecorded portion formed in a recording area such as recording-unrecording-recording is changed to a value of an optical characteristic of an unrecorded area where recording is not performed. On the other hand, since the relative value is within ± 50%, the difference in reflectance between the unrecorded area of the recording area and the unrecorded area of the unrecorded area becomes small, and the unrecorded area is reproduced and recorded continuously from the recording area. Even in such a case, the optical pickup can stably follow the truck.
According to an eleventh aspect of the present invention, the change in the apparent optical characteristic of the recording unit is set so that the reflectivity is reduced by recording. Normally, an information recording medium has pre-pits or the like indicating an address before recording, and its signal is set in a direction in which the reflectance decreases, but the signal after recording also has a direction in which the reflectance decreases. However, since the signal detection directions are the same, circuit design and the like are facilitated.
According to the twelfth aspect of the present invention, the solvent is permeated into the altered part and the non-altered part, and the solubility is compared to confirm the altered part, so that the recording range can be easily confirmed. As a result, the information can be easily reflected on the recording conditions, and good recording can be performed.
[Brief description of the drawings]
FIG. 1 is an example of an enlarged sectional view of a main part showing a configuration of an optical information recording medium according to the present invention.
FIG. 2 is a plan view of an optical information recording medium according to the present invention.
FIG. 3 is an example of an enlarged sectional view of a main part showing a recording state of an optical information recording medium according to the present invention.
FIG. 4 is another example of a main part enlarged sectional view showing a recording state of the optical information recording medium according to the present invention.
FIG. 5 is another example of a main part enlarged sectional view showing a recording state of the optical information recording medium according to the present invention.
FIG. 6 is another example of a main part enlarged sectional view showing a recording state of the optical information recording medium according to the present invention.
FIG. 7 is another example of a main part enlarged sectional view showing a recording state of the optical information recording medium according to the present invention.
FIG. 8 is another example of a main part enlarged sectional view showing a recording state of the optical information recording medium according to the present invention.
FIG. 9 is another example of a main part enlarged sectional view showing a recording state of the optical information recording medium according to the present invention.
FIG. 10 is another example of a main part enlarged sectional view showing a recording state of the optical information recording medium according to the present invention.
FIG. 11 is another example of an enlarged sectional view of a main part showing a recording state of the optical information recording medium according to the present invention.
FIG. 12 is another example of a main part enlarged sectional view showing a recording state of the optical information recording medium according to the present invention.
FIG. 13 is another example of a main part enlarged sectional view showing a recording state of the optical information recording medium according to the present invention.
FIG. 14 is another example of a main part enlarged sectional view showing a recording state of the optical information recording medium according to the present invention.
FIG. 15 is an example of an enlarged sectional view of a main part showing a state of deterioration of the optical information recording medium according to the present invention.
FIG. 16 is another example of an enlarged sectional view of a main part showing a state of deterioration of the optical information recording medium according to the present invention.
FIG. 17 is a diagram for explaining combined light of reflected light at each interface of the optical information recording medium according to the present invention.
FIG. 18 is another example of a main part enlarged cross-sectional view showing the configuration of the optical information recording medium according to the present invention.
FIG. 19 is another example of a main part enlarged cross-sectional view showing the configuration of the optical information recording medium according to the present invention.
FIG. 20 is a flowchart of manufacturing an optical information recording medium according to the present invention.
FIG. 21 is a diagram for explaining multiple reflection between layers.
[Explanation of symbols]
1 Transparent substrate
2 Pre-format pattern
3 Light absorption layer (information recording section)
4 Heat receiving layer
5 reflective layer
6 Underlayer
7 Middle class
10 protective layer
1a center hole
2a guide groove
2b pre-pit
2c @ land

Claims (12)

An information recording medium having a layer structure in which a heat-receiving layer containing a dye material is stacked on the light-absorbing layer so as to have a thickness of 200 nm or less. The medium is irradiated with light having a Gaussian distribution and recorded. As a result, the information recording medium is characterized in that the recording is performed by the heat receiving layer being degraded inside and outside the recording mark area where the light intensity is increased for recording. An information recording medium having a layer structure in which a heat-receiving layer containing a dye material is stacked on the light-absorbing layer so as to have a thickness of 200 nm or less. The medium is irradiated with light having a Gaussian distribution and recorded. As a result, the amount of the dye material decreases from the outer peripheral portion due to the deterioration of the dye material in the heat receiving layer in a portion corresponding to the central region of the Gaussian distribution. The dye material according to claim 1 or 2, wherein the dye material is at least one dye selected from the group consisting of cyanine, phthalocyanine, naphthalocyanine, merocyanine, azo, and formazan chelate dyes. Information recording medium. 4. The information recording medium according to claim 1, wherein at least the heat receiving layer is deformed by irradiation with light having a Gaussian distribution. The information recording according to any one of claims 2 to 4, wherein the heat receiving layer is recorded by altering a portion inside and outside a recording mark area whose light intensity is increased for recording. Medium. The information recording medium according to any one of claims 1 to 5, wherein a reflection layer is further laminated on the heat receiving layer. Irradiates a laser spot represented by r = λ / 2NA × K (where λ represents the wavelength used for recording, NA represents the aperture ratio of the lens, and K = 0.6 to 1.22). The information recording medium according to any one of claims 1 to 6, wherein an area obtained by moving is used as a mark area. The information recording medium according to any one of claims 1 to 7, wherein the heat-receiving layer has a deteriorated portion and a non-transformed portion peeled off due to deterioration, and selectively adheres to another adjacent layer. 9. The information recording medium according to claim 1, wherein the deterioration of the heat receiving layer can be confirmed as a change in the melting characteristics of the material after film formation. A method for recording information using the information recording medium according to any one of claims 1 to 9, wherein an apparent amount of change in optical characteristics of an unrecorded portion after recording is determined by an unrecorded portion before recording. An information recording method characterized by being set to be within ± 50% as a relative value with respect to the value of the optical characteristic of (1). 11. The recording method for an information recording medium according to claim 10, wherein a change in an apparent optical characteristic of the recording unit is set so that the reflectance is reduced by recording. 9. The method for confirming a deteriorated part according to claim 8, wherein a solvent is permeated into the deteriorated part and the non-deteriorated part, and the solubility is compared.

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