【発明の詳細な説明】
く利用分野〉
本発明はレーザー等の光により、＋ｆｔ報の記録、再生
、消去等を行なう光磁気記録媒体に関する．更に詳細に
は、透明基板一Ｅに膜面に垂直な方向に磁化容易方向を
有した金属薄膜よりなる記録層を形成し、光熱磁気効果
により情報を記録し、磁気光学効果により再生する光磁
気記録媒体に関する．く従来技術〉
光記録媒体は高密度・大容量の情報記録媒体として種々
の研究開発が行なわれている．特に情報の消去可能な光
磁気記録媒体は応用分野が広く種々の材料・システムが
発表されており、その実用化が待望されている．
上述の光磁気記録材料としては、例えば、特開昭５２−
３１７０３号公報記載のＦｅＴｂ、特開昭５６−１２６
９０７号公報記社のＦｅＴｂＧｄ、特開昭５８−７３７
４６号公報記載のＦｅｌｂＣｏ、ＦｅＣｏＤｙ、特開昭
６１−１６５８４６号公報記載のＦｅｅｄ等既に多くの
提案がある。しかし、これらの情報の消去可能な光磁気
記録媒体の実用化には、記録、再生特性のより一層の向
上が必要である．これに対し、光磁気記録層上、もくし
はその上に誘電体層を介して金属反射層を設ける方法が
提案されている．この方式はカー効果とファラデー効果
の併用により高いＣ／Ｎ比を得る点で優れている．従来
この金属反射層として、＾１を用いたらのく特開昭５８
−８３３４６号公報、特開昭５９−１３２４３４号公報
、） 、Ｃｕを用いたもの（特開昭５９−８１５０号公
報）、Ａ１系合金を用いたもの（特開昭６２−１３７７
４３号公報、特開昭６４−４９３８号公報）、ステンレ
スを用いたもの（特開昭５９−１７１０５４号公報）、
１０を用いたもの（特開昭６２−５２７４４号公報）、
非品質金属膜を用いたもの（特開昭６１−５７０５３号
公報）等か提案されている．しかしながら、高反射率の
＾ｌ，Ｃｕ等を用いた場合にはその高熱伝導性のため記
録感度が大幅に低下し、一方比較的熱伝導性の低いステ
ンレス、１ｅを用いた場合には記録感度は向上するが反
射率か低いため、十分なＣ／Ｎ比が得られないという欠
点を有する．
く発明の目的〉
本発明はかかる現状に鴛みなされたもので、高感度で高
Ｃ／Ｎ比の光磁気記録媒体を提供することを目的とした
ものである．
く発明の構成及び作用〉
本発明者らは、上述の欠点を克服すべく鋭意検討した結
果、特定の物質で金属反射層を形或することにより、記
録感度、Ｃ／Ｎが高く、更に経時安定性に潰れた光磁気
記録媒体が得られることを見出した．
即ち本発明は、金属反射層を有する光磁気記録媒体にお
いて、該金属反射層がＡＱに八ｕを０．５〜３０ａｔ％
（原子％）含有せしめ、さらにＴａ又はＴｉの少くとも
一秤を０．５〜１５ａｔ％含有せしめたＡｇ合金からな
ることを特徴とする光磁気記録媒体である．上述の本発
明は以下のようにしてなされたものである．すなわち、
本発明者らは、Ｃ／Ｎ向上目的に高反射率の八ｇ膜に着
目したが、ＡＱは耐食性のわるい材料であり、八〇膜の
みでは実川的でない．そこで、その改良として他金属の
添加を検討したところ、スライドガラス上に形成したＣ
ｕを０．５〜３０ａｔ％添加した＾ｇＣｕ合金膜は高反
射率で、光磁気記録媒体の標準的な加速劣化テスト条件
である８０”Ｃ８５％相対湿度雰囲気下で７２時間以−
Ｅ放置しても反射率が低下せず、耐久性もあることが判
明した．なお、Ｃｕの含有量が０．５８ｔ％より少くて
も、３０８ｔ％より多くても２４時間以内に反射率は初
期値の９割以下に低下した， ＡｇＣｕ合金膜は上述の
通り高反射率（例えばＡｇ８５Ｃｕ１５（添字はａｔ％
組成）合金膜では８３０ｎｉの波長で９８％の反射＊）
であり、耐久性ら悪くないか、このＡｇＣｕ膜は熱伝導
性が高く、そのためこれを反射膜とする光磁気記録媒体
では記録感度が低下することがさらに判明した．本発明
者らは、さらにこの点の改良を第３元素の添加に着目し
、ｌｉｉ２意研究の結果、ＡｇＣｕ膜にＴａ又は丁１の
少くとも一押を０．５〜１５ａｔ％添加すると、記録感
度と耐食性が大きく向上することを見い出し、本発明に
想到した．
なお、Ｔａ， Ｔｉの含有量がこの範囲より少いと記録
感度の向上の効果はなく、また逆に多くなると反射率が
低下し、Ｃ／Ｎが悪くなる．更にＴａ， Ｔｉの含有量
は、感度向上効果が大きく、且つＣ／Ｎ向上の効果が瓜
ｌ害されない点で２〜１０ａｔ％かより好ましい．なお
、経時安定性を更に改善するために、Ｃｒ， Ｎｂ、ｌ
ｌｅなどの他の元素を少ｉ添加してもよい．
この金属反射層の膜厚は１００〜１０００人が好ましく
、２００〜７０α入が更に好ましい．厚すぎる場合には
感度が低下し、薄すぎる場合には反射率が低下しＣ／Ｎ
がわるくなる．
なお、本発明において金属反射層の光磁気記録層開と反
対側に接して、付加的に１１等の熱伝運率の小さい金属
膜、又は誘電体膜を設けてもよい．特に熱伝導を抑える
ために本発明の金属反射層か４００八以下と薄いときに
はＴｉ等の金属膜を設けると反射率の低下を防止すると
ともに耐食性が向上して更に好ましい結果が得られる．
同様に誘電体膜は、光磁気記録媒体がきわめてきびしい
環境下で仙川されることが想定される時は、保護層とし
て設けるとよい．
前記金属反射ノーの形戒方法としては、公知の真空蒸着
法、スパッタリング法、イオンビームスパッタリング法
、ＣＶＤ法などが考えられるか、下地層との接着性、合
金組成の制御性、組成分布などの点でスパッタリング法
が好ましい．また膜の堆積速度、スパッタガス圧などは
、生産性、Ｉｆｆ応力を考慮し、適宜選択される．
本発明の光磁気記録層としては、光熱磁気効果により記
録できるものであればよく、公知の、膜而に垂直な方向
に磁化容易方向を有し、磁気光学効果の大きい磁性金属
薄膜、例えば前述のｒｅｌｂ合金、ＦｅＴｂＣｏ合金、
ＦｅＴｂＧｄ合金及びＮｄＤｙｌ’ｅＣｏ合金、等の希
土類元素一遷移金属元素の非品質合金が代表例として挙
げられる．光磁気記録層の膜厚は１５０〜１０００入、
好ましくは２００〜５００入である．本発明における′
＃．磁気記録媒体は、その金属反射層が光磁気記録層の
光入射面と反対側に形成される点を除いてその構戒は特
に限定されない．なお、金属反射層は光磁気記録層上に
直接設けても、またその上に感度、Ｃ／Ｎ向上の目的で
透明誘電体層を介して設けてもよい．しかし本発明の前
述の１８又は丁１の少なくとも一方とＣｕを含有ずるＡ
（Ｉ合金からなる金属反射膜は光磁気記録層に接して直
接設けた構成で、その記録感度とＣ／Ｈにおいて実用上
充分な性能を示し、上記透明誘電体層が不要となるので
、この構成が生産性と媒体コストの観点より好ましい．
なお、光磁気記録層と金属反射層との間に、透明誘電体
層を設ける場合においても、この透明誘電体層は最適性
能を得るためには６００入以下と薄くする必要があり、
その断熱作用が小さくなるため、本発明は効果的である
．また、一般的に、該透明誘電体層が厚くなる程、その
断熱効果が高くなり、本発明の金属反射膜のＴａ又はＴ
ｉの含有量は少なくてよい．
本発明の光磁気記録媒体は、また、基板と光磁気記録層
の間に、Ｃ／Ｎ向上、媒体の反射率低減、さらには透湿
防止の目的で透明誘電体層を設けてもよい．
上記構成に用いる光磁気記録層の基板側，金属反射層側
の両透明誘電体層としては、その目的により光干渉効果
、力一効果エンハンスメント等の効果を奏することが必
要で、ある程度以上の高屈折率を有することが好ましい
．また使用するレーザー光に透明であることが必要であ
り、透明誘電体層としては公知の通り金属の酸化物、窒
化物、硫化物、炭化物、弗化物もしくはこれらの複合体
が適用できる．具体的には酸化ケイ素、酸化インジウム
、酸化タンタル、酸化アルミニウム、チッ化ケイ素、チ
ッ化アルミニウム、チヅ化チタン、硫化亜鈴、フッ化マ
グネシウム、フッ化アルミニウム、炭化ケイ素及びこれ
らの複合物が挙げられるが、これに限定されないことは
言うまでもない．またバリレン、ポリイミド、バラフィ
ンなど有機物も適用できる．これら透明誘電体層の膜厚
は、媒体横成、屈折率により最！！ｉ値が変化し、一義
的に決めることはできないが、通常４００〜１５００六
程度、特に５００〜１０００八が好適に用いられる．こ
れら透明透電体層は常法により達成される．關えば前述
の無機物よりなるものは公知の真空蒸着法、スパッタリ
ング法、イオンビームスパッタリング法、ＣＶＤ法等で
作製される．
また基板としては、ガラス、アクリル樹脂、ポリカーホ
ネート樹脂、エボキシ樹脂、４−メチルベンテン樹脂及
びそれらの変成品などが好適に用いられるが、機械的強
度、価格、耐候性 耐熱性、透湿産の点でポリカーボネ
ート樹脂が好ましい．以下、本発明の実施例を説明する
が、本発明は以下の実施例に限定されるものではない．
く実施例．比較例〉
直径１３０−、厚さ１．２順の円盤で１．６μｍピッチ
のグループを有するポリカーボネート樹脂（ＰＣ）製の
ディスク基板を、３ターゲット設置可能な高周波マグネ
トロンスバッタ装置（アネルバ■ＩｊｉＪＳＰＦ−４３
０１１型）の真空槽内に配置し、４Ｘ１０’■０ｒ『に
なるまで排気した．
次にＡ『、Ｎ２の混合ガス（Ａｒ ： Ｎ２ ＝７０：
３０ｖｏｌ％）を真空槽内に導入し、圧力１０ｎ Ｔ
ｏｒｒになるようにＡｒ／ Ｎ２混合ガス流量を調整し
た．夕一ゲヅトとしては直径１００＋ｎｉ，厚さ５曲の
ＡｌｓｏＳｌｓｏ（以下、添数字は組成（原子％）を示
す）の焼結体からなる円盤を用い、放電電力５００Ｗ，
放電周波数１３．５６Ｈｌｌｚで高周波スパッタリング
を行ない、ＰＣ基板を回転（自転）させながら、透明誘
電体として＾ＩＳｉＮ Ｉ漠を８０Ｏ Ａ堆積した．続
いて光磁気記録層として、Ｔｂ２１『ｅ７１Ｃ０８合金
ターゲットを用い、Ａ『ガス圧２ＩＩＴｏｒｒ、放ｔ電
力ｉｓｏｗの条件で高周波スパッタリングを行ない、約
３００入のＴｂＦｅＣＯ合金膜を堆積した．更に引き続
いて、”８！）”１５合金ターゲットを用い、適宜５Ｉ
ｌｌＩ角Ｘ １ ｍ ｔのＴａチップをターゲット上に
配し、＾ｒカス圧２１１ＴＯｒｒ、放電電力１００−の
条件で高周波スパッタリングを行い、表−１の各組成で
４００Ａの金属反射層を堆積し、ＰＣ基板／ＡＳｉＮ
／ｌｂＦｅｃｏ／金属反射層の積層楕戒の光磁気ディス
クを得た．金属反射層の各ＡｉＪＣＬＩＴａ合金膜のＩ
ａ量はＡｇＣｕ合金ターゲット上のＴａチップの数を変
化させて各組成に調整した．
これら各層の形成時において、ＰＣ基板は２０ｒｐｌで
回転させた．
得られた光磁気ディスクは光磁気記録再生装置（ナカミ
チ■製０８３−１０００型）を用い、下記条件でＣ／Ｎ
とｆｉ適記録レーザーバワーを評価した．書込み時の半
導体レーザーパワーを変化させ、再生信号の二次高調波
が最小となる時が最適記録条件とした．
［記録条件］
ディスク回転速度： １８００ｒＤＩ ，記鎚トラック
位置二半径３０ＩＩＩ１１位置、記録周波数：３．７Ｈ
ＩＩｚ、記録時の印加磁界＝５００エルステッド
［再生条件］
ディスク回転速度： １８００ｒｐｌ 、読出レザーパ
ワー： １．２ｍＷ
Ｉ＆週記録レーザーバワー及びＣ／Ｎの測定結果を表−
１に示す．
なお、表−１の比較例１は金属反射層以外は実施例１〜
４と同じ横或で、金属反射層を実施例１〜４のＴａチッ
プを除去して形成したＴａを含有しない”’８５Ｃｕ１
５合金とした光磁気ディスクである．また、比較例２と
して、金属反射層を除いた池の構成は実施例１〜４と同
じで、金属反射層としてＴａチップを配したＡ１ターゲ
ットを用い、実施例１〜４の金属反射層と同じように高
周波スパッタリングすることにより、＾Ｉ９２Ｔａａ合
金膜を４０ＯＡ積層形或した光磁気ディスクを作製し、
同様に評価した．
また表−１の比較例１の最適記録レーザーバワ− １０
ＩＩＷ以上は、用いたレーザーの最大出力１０問でも記
録できなかったことを表わす．
表−１
し、そのｆ＆紫外線照射により硬化させ、約２０μｍの
有機保護層を設けた．これらのサンプルを、温度８０℃
、湿度８５％の条件で１０００ｗｆ間の加速試験を行な
ったところ、実施例２では全く変化が見られなかったが
、比較例２ではピンホールが十数個発生した．
更に、実施例１〜４と同じにして、ただ丁ａのかかわり
にＴｉのチップを＾ｇＣｕターゲット上に配置して金属
反射層を表−２のＡｇＣｕｌ ｉ合金とした以外は全く
同じ構成の光磁気ディスクのサンプルを作成し、同じよ
うにして評価した．その結果を表−２に示す．
表−２
また実施関１と比較例２のディスクの金属反肘層上に、
スピンコーターで紫外線硬化型のフェノールノボラック
エボキシアクリレート樹脂を塗布以上、実施例に示した
如く、本発明のＣｕと、Ｔａ又はＴｉの少くとも一方と
を含有した八〇合金からなる金属反射膜ではＣ／Ｎ、感
度が優れ、かつ耐久性も高い光磁気記録媒体を得ること
ができる．特にＴａ， Ｔｉの含有量か２ａｔ％以上の
範囲でζよ、最適記録レーサーパワーの低下すなわち記
録感度の向上か顕著で、かつＣ／Ｎも公知の、例えば＾
ｌＴａ合金膜を反ｑ・ｔ Ｉｇ！とずる光磁気ディスク
より格段にすぐれている．かかる効果の点でＴａ、Ｔｉ
の富有量は２〜１０３１％が特に好ましい．Detailed Description of the Invention Field of Application The present invention relates to a magneto-optical recording medium in which +ft information is recorded, reproduced, erased, etc. using light such as a laser. More specifically, a recording layer made of a metal thin film having an easy magnetization direction perpendicular to the film surface is formed on a transparent substrate 1E, and information is recorded by a photothermal magnetic effect and reproduced by a magneto-optic effect. Regarding recording media. Prior Art> Various research and developments are being conducted on optical recording media as high-density, large-capacity information recording media. In particular, a wide variety of materials and systems have been announced for use in erasable magneto-optical recording media, and their practical application is eagerly awaited. As the above-mentioned magneto-optical recording material, for example, JP-A-52-
FeTb described in Publication No. 31703, JP-A-56-126
FeTbGd of Publication No. 907, JP-A-58-737
There have already been many proposals such as FelbCo and FeCoDy described in Japanese Patent Laid-Open No. 165846/1984. However, in order to put these information erasable magneto-optical recording media into practical use, it is necessary to further improve the recording and reproducing characteristics. In contrast, a method has been proposed in which a metal reflective layer is provided on the magneto-optical recording layer or on top of it with a dielectric layer interposed therebetween. This method is superior in that it obtains a high C/N ratio by combining the Kerr effect and Faraday effect. Conventionally, ^1 was used as this metal reflective layer in Taranoku JP-A-58
-83346, JP-A-59-132434), those using Cu (JP-A-59-8150), and those using A1 alloy (JP-A-62-1377).
43, JP-A-64-4938), stainless steel (JP-A-59-171054),
10 (Japanese Unexamined Patent Publication No. 62-52744),
A method using a non-quality metal film (Japanese Unexamined Patent Publication No. 61-57053) has been proposed. However, when materials such as ^l, Cu, etc. with high reflectivity are used, the recording sensitivity decreases significantly due to their high thermal conductivity, while when stainless steel and 1e, which have relatively low thermal conductivity, are used, the recording sensitivity decreases. Although it improves the reflectance, it has the disadvantage that a sufficient C/N ratio cannot be obtained because the reflectance is low. OBJECTS OF THE INVENTION The present invention has been made in view of the current situation and aims to provide a magneto-optical recording medium with high sensitivity and a high C/N ratio. Structure and operation of the invention As a result of intensive studies to overcome the above-mentioned drawbacks, the present inventors have found that by forming a metal reflective layer with a specific material, recording sensitivity and C/N can be high, and It was discovered that a magneto-optical recording medium with excellent stability could be obtained. That is, the present invention provides a magneto-optical recording medium having a metal reflective layer, in which the metal reflective layer has an AQ content of 0.5 to 30 at%.
(atomic %) and further contains at least 0.5 to 15 at % of Ta or Ti. The invention described above was made as follows. That is,
The present inventors focused on an 8g film with high reflectance for the purpose of improving C/N, but AQ is a material with poor corrosion resistance, and using only an 80g film is not practical. Therefore, we investigated the addition of other metals as an improvement, and found that the C
The Cu alloy film containing 0.5 to 30 at% of u has a high reflectance and can be used for more than 72 hours in an 80"C 85% relative humidity atmosphere, which is the standard accelerated deterioration test condition for magneto-optical recording media.
EIt was found that the reflectance did not decrease even after being left unused, and that it was durable. In addition, even if the Cu content was less than 0.58 t% or more than 308 t%, the reflectance decreased to less than 90% of the initial value within 24 hours. As mentioned above, the AgCu alloy film has a high reflectance ( For example, Ag85Cu15 (the subscript is at%
Composition) Alloy film has 98% reflection at a wavelength of 830ni*)
It was further found that this AgCu film has high thermal conductivity, which may not be bad in terms of durability, and therefore the recording sensitivity of a magneto-optical recording medium using this film as a reflective film is lowered. The present inventors further focused on the addition of a third element to improve this point, and as a result of a two-dimensional study, it was found that when 0.5 to 15 at% of at least one of Ta or Ta was added to the AgCu film, it was possible to record We discovered that sensitivity and corrosion resistance were greatly improved, and came up with the present invention. Note that if the content of Ta and Ti is less than this range, there is no effect of improving the recording sensitivity, and on the other hand, if the content is too large, the reflectance decreases and the C/N deteriorates. Further, the content of Ta and Ti is more preferably 2 to 10 at%, since the sensitivity improvement effect is large and the C/N improvement effect is not adversely affected. In addition, in order to further improve the stability over time, Cr, Nb, l
A small amount of other elements such as le may be added. The thickness of this metal reflective layer is preferably 100 to 1000, more preferably 200 to 70. If it is too thick, the sensitivity will decrease, and if it is too thin, the reflectance will decrease and the C/N
I feel sick. In the present invention, a metal film having a low thermal conductivity such as No. 11 or a dielectric film may be additionally provided in contact with the metal reflective layer on the side opposite to the opening of the magneto-optical recording layer. In particular, when the metal reflective layer of the present invention is as thin as 400% or less in order to suppress heat conduction, providing a metal film such as Ti prevents a decrease in reflectance and improves corrosion resistance, resulting in more favorable results.
Similarly, a dielectric film may be provided as a protective layer when the magneto-optical recording medium is expected to be used in extremely harsh environments. Possible methods for controlling the metal reflection include known vacuum evaporation methods, sputtering methods, ion beam sputtering methods, CVD methods, etc.; Therefore, sputtering method is preferable. Further, the film deposition rate, sputtering gas pressure, etc. are appropriately selected in consideration of productivity and If stress. The magneto-optical recording layer of the present invention may be any material as long as it can record by photothermal magnetism, and may be a known magnetic metal thin film having an easy magnetization direction perpendicular to the film and having a large magneto-optic effect, such as the above-mentioned thin film. relb alloy, FeTbCo alloy,
Representative examples include non-quality alloys of rare earth elements and transition metal elements, such as FeTbGd alloys and NdDyl'eCo alloys. The film thickness of the magneto-optical recording layer is 150 to 1000 mm,
Preferably it is 200 to 500 pieces. ′ in the present invention
＃． The structure of the magnetic recording medium is not particularly limited except that the metal reflective layer is formed on the side opposite to the light incident surface of the magneto-optical recording layer. The metal reflective layer may be provided directly on the magneto-optical recording layer, or may be provided thereon via a transparent dielectric layer for the purpose of improving sensitivity and C/N. However, A containing at least one of the above-mentioned 18 or 1 of the present invention and Cu
(The metal reflective film made of I alloy is provided directly in contact with the magneto-optical recording layer, and exhibits practically sufficient performance in terms of recording sensitivity and C/H, and the transparent dielectric layer described above is not required. This configuration is preferable from the viewpoint of productivity and media cost. Note that even when a transparent dielectric layer is provided between the magneto-optical recording layer and the metal reflective layer, this transparent dielectric layer must be It needs to be thin, less than 600 pieces,
The present invention is effective because its heat insulation effect is reduced. In addition, in general, the thicker the transparent dielectric layer, the higher its heat insulating effect.
The content of i may be small. In the magneto-optical recording medium of the present invention, a transparent dielectric layer may be provided between the substrate and the magneto-optical recording layer for the purpose of improving C/N, reducing the reflectance of the medium, and further preventing moisture permeation. Both the transparent dielectric layers on the substrate side and the metal reflective layer side of the magneto-optical recording layer used in the above structure need to exhibit effects such as optical interference effect and force-effect enhancement depending on the purpose. It is preferable to have a refractive index. It is also necessary to be transparent to the laser beam used, and as the transparent dielectric layer, metal oxides, nitrides, sulfides, carbides, fluorides, or composites of these can be used. Specific examples include silicon oxide, indium oxide, tantalum oxide, aluminum oxide, silicon nitride, aluminum nitride, titanium nitride, dumbbell sulfide, magnesium fluoride, aluminum fluoride, silicon carbide, and composites thereof. , it goes without saying that it is not limited to this. Organic materials such as varylene, polyimide, and paraffin can also be used. The thickness of these transparent dielectric layers depends on the medium composition and refractive index. ! Although the i value varies and cannot be determined uniquely, it is usually about 400 to 1,500, particularly preferably 500 to 1,000. These transparent conductive layers are achieved by conventional methods. In this regard, those made of the above-mentioned inorganic materials are manufactured by known vacuum evaporation methods, sputtering methods, ion beam sputtering methods, CVD methods, etc. Glass, acrylic resin, polycarbonate resin, epoxy resin, 4-methylbentene resin, and modified products thereof are preferably used as the substrate, but mechanical strength, price, weather resistance, heat resistance, and moisture permeability are preferred. From this point of view, polycarbonate resin is preferable. Examples of the present invention will be described below, but the present invention is not limited to the following examples.
Example. Comparative Example> A polycarbonate resin (PC) disk substrate with a diameter of 130 mm and a thickness of 1.2 mm and groups with a pitch of 1.6 μm was installed using a high-frequency magnetron scattering device (ANELVA ■IjiJSPF-) capable of installing 3 targets. 43
011 type) in a vacuum chamber and evacuated to 4X10'■0r'. Next, a mixed gas of A', N2 (Ar: N2 = 70:
30vol%) was introduced into the vacuum chamber at a pressure of 10nT.
The Ar/N2 mixed gas flow rate was adjusted so that it was orr. As the Yuichi gate, a disk made of a sintered body of AlsoSlso (hereinafter, the suffix indicates the composition (atomic %)) with a diameter of 100+ni and a thickness of 5 was used, and the discharge power was 500 W.
High-frequency sputtering was performed at a discharge frequency of 13.56 Hllz, and 800A of ^ISiN I was deposited as a transparent dielectric while rotating (rotating) the PC board. Subsequently, as a magneto-optical recording layer, about 300 TbFeCO alloy films were deposited by high-frequency sputtering using a Tb21 e71C08 alloy target under conditions of A gas pressure of 2 II Torr and discharge power isow. Furthermore, using the "8!)" 15 alloy target, 5I was applied as appropriate.
A Ta chip with an llI angle of 1 m t was placed on the target, and high-frequency sputtering was performed under the conditions of a gas pressure of 211 TOrr and a discharge power of 100 - to deposit a metal reflective layer of 400 A with each composition shown in Table 1. PC board/ASiN
/lbFeco/A magneto-optical disk with a laminated elliptical metal reflective layer was obtained. I of each AiJCLITa alloy film of the metal reflective layer
The amount of a was adjusted for each composition by changing the number of Ta chips on the AgCu alloy target. During the formation of each of these layers, the PC board was rotated at 20 rpl. The obtained magneto-optical disk was subjected to C/N using a magneto-optical recording/reproducing device (model 083-1000 manufactured by Nakamichi ■) under the following conditions.
and evaluated the fi-appropriate recording laser power. The semiconductor laser power during writing was varied, and the optimal recording condition was set when the second harmonic of the reproduced signal was minimized. [Recording conditions] Disc rotation speed: 1800rDI, recording track position 2 radius 30III11 position, recording frequency: 3.7H
IIz, Magnetic field applied during recording = 500 oersteds [Reproduction conditions] Disc rotation speed: 1800 rpl, Read laser power: 1.2 mW I & Week Recording laser power and C/N measurement results are shown in the table.
Shown in 1. Note that Comparative Example 1 in Table 1 is the same as Examples 1 to 3 except for the metal reflective layer.
'85Cu1, which does not contain Ta, was formed by removing the Ta chips of Examples 1 to 4 and formed a metal reflective layer on the same side as 4.
This is a magneto-optical disk made of 5 alloy. In addition, as Comparative Example 2, the configuration of the pond except for the metal reflective layer was the same as in Examples 1 to 4, and an A1 target with Ta chips arranged as the metal reflective layer was used, and the metal reflective layer of Examples 1 to 4 was Similarly, by high-frequency sputtering, a magneto-optical disk with a 40OA laminated I92Taa alloy film was fabricated.
It was evaluated in the same way. In addition, the optimum recording laser power of Comparative Example 1 in Table 1 is 10
A score of IIW or higher means that it was not possible to record even with the maximum output of the laser used for 10 questions. Table 1 was cured by F&UV irradiation to form an organic protective layer of about 20 μm. These samples were heated to a temperature of 80°C.
When an accelerated test was conducted for 1000 wf under the condition of 85% humidity, no change was observed in Example 2, but more than ten pinholes were observed in Comparative Example 2. Furthermore, a light beam with the same structure as Examples 1 to 4 was prepared, except that a Ti chip was placed on the Cu target in place of the cylindrical plate, and the metal reflective layer was made of the AgCul i alloy shown in Table 2. A magnetic disk sample was created and evaluated in the same way. The results are shown in Table 2. Table 2 Also, on the metal anti-elbow layer of the discs of Example 1 and Comparative Example 2,
Coating an ultraviolet curable phenol novolak epoxy acrylate resin with a spin coater As shown in the examples, the metal reflective film made of the 80 alloy of the present invention containing Cu and at least one of Ta or Ti /N, a magneto-optical recording medium with excellent sensitivity and high durability can be obtained. In particular, when the content of Ta or Ti is 2 at% or more, the optimum recording laser power decreases, that is, the recording sensitivity increases, and the C/N is also known, for example.
Ig! It is far superior to the magneto-optical disk. In terms of this effect, Ta, Ti
It is particularly preferable that the richness of .