JP2005108407A - Magnetic recording medium and substrate for magnetic recording medium - Google Patents
Magnetic recording medium and substrate for magnetic recording medium Download PDFInfo
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本発明は、磁気記録媒体用基板、及び記録層を含む磁気記録媒体に関するものである。 The present invention relates to a magnetic recording medium substrate and a magnetic recording medium including a recording layer.
磁気記録の分野において、ハードディスク装置による情報記録はパーソナルコンピュータを初めとするコンピュータの一次外部記録装置として必須である。ハードディスクドライブはその記録密度向上に伴い、従来の面内磁気記録方式に代わり、より高密度な記録が可能な垂直磁気記録方式の開発が進められている。 In the field of magnetic recording, information recording by a hard disk device is essential as a primary external recording device for computers such as personal computers. As the recording density of hard disk drives increases, development of perpendicular magnetic recording systems capable of higher density recording is being promoted in place of conventional in-plane magnetic recording systems.
垂直磁気記録では、隣接ビットからの磁場が磁化方向と同じ方向となり、隣接ビットの間で閉磁路を形成し、水平磁気記録に比較して自分自身の磁化による自己減磁場（以下、反磁場と呼ぶ。）が少なく、磁化状態が安定する。
磁性膜厚の点においては、垂直磁気記録において記録密度向上に伴って特に薄くする必要が無く、これらの点から、垂直磁気記録は、反磁場軽減とＫｕＶ（Ｋｕは異方性エネルギー、特に磁気記録の場合は結晶磁気異方性エネルギーを表し、Ｖは単位記録ビット体積を表す。）の値を確保できるため、熱揺らぎによる磁化に対する安定性が大きく、記録限界を大きく先に拡大する事が可能となる記録方式と言える。記録媒体としては、水平記録媒体との親和性も高く、磁気記録の書込みや読み出しも基本的には従来使われていたものと同じような技術が使用できる。
In perpendicular magnetic recording, the magnetic field from adjacent bits is the same as the magnetization direction, and a closed magnetic circuit is formed between adjacent bits. Compared with horizontal magnetic recording, self-demagnetization field (hereinafter referred to as demagnetizing field) due to its own magnetization. And the magnetization state is stabilized.
In terms of magnetic film thickness, it is not necessary to reduce the thickness in perpendicular magnetic recording as the recording density is improved. From these points, perpendicular magnetic recording is effective in reducing demagnetizing field and KuV (Ku is anisotropic energy, especially magnetic In the case of recording, it represents the magnetocrystalline anisotropy energy, and V represents the unit recording bit volume.), The stability against magnetization due to thermal fluctuation is great, and the recording limit can be greatly expanded first. This is a possible recording method. As a recording medium, the compatibility with a horizontal recording medium is high, and writing and reading of magnetic recording can basically use the same techniques as those conventionally used.
垂直磁気記録用媒体においては、記録層に加え基板上に軟磁性裏打ち層（典型的にはパーマロイ等）、記録層（ＣｏＣｒ系合金、ＰｔＣｏ層とＰｄとＣｏの超薄膜を交互に数層積層させた多層膜、ＳｍＣｏアモルフアス膜などが候補材料等）、保護層、潤滑層等を順次積層させた垂直二層式磁気記録媒体が広く検討されている。
垂直二層式磁気記録媒体は、磁気機能層として記録層しか有しない垂直磁気記録媒体に比して、書き込み特性の点で非常に優れている。
この垂直二層式磁気記録媒体における裏打ち層は、軟磁性であり、かつ厚みも概ね１００ｎｍ以上５００ｎｍ程度の厚さが必要とされる。軟磁性裏打ち層は、上部記録層からの磁束の通り道であるとともに、記録ヘッドからの書き込み用磁束の通り道ともなる。そのため、永久磁石磁気回路における鉄ヨークと同じ役割を果たしており、記録層に比して大幅に厚くする必要がある。
In a perpendicular magnetic recording medium, in addition to a recording layer, a soft magnetic backing layer (typically permalloy, etc.) and a recording layer (CoCr alloy, PtCo layer and Pd and Co ultrathin films are alternately laminated in several layers. Multilayer films, SmCo amorphous films, etc., which are candidate materials, etc.), perpendicular two-layer magnetic recording media in which a protective layer, a lubricating layer, and the like are sequentially laminated have been widely studied.
The perpendicular double-layer magnetic recording medium is very excellent in terms of writing characteristics as compared with a perpendicular magnetic recording medium having only a recording layer as a magnetic functional layer.
The backing layer in this perpendicular two-layer magnetic recording medium is soft magnetic and needs to have a thickness of about 100 nm to about 500 nm. The soft magnetic underlayer serves as a path for magnetic flux from the upper recording layer and also as a path for magnetic flux for writing from the recording head. Therefore, it plays the same role as the iron yoke in the permanent magnet magnetic circuit, and needs to be significantly thicker than the recording layer.
水平記録媒体において非磁性Ｃｒ系下地層を形成するのに比較し、垂直二層式記録媒体において軟磁性裏打ち層を形成することは簡単ではない。通常、水平記録媒体の各層は、全てドライプロセス（主にマグネトロンスパッタ）で形成されている（特許文献１）。垂直二層式記録媒体においても、記録層のみならず軟磁性層をドライプロセスにより形成しようとする方法が種々検討されている。しかしながら、ドライプロセスによる軟磁性層の製作では、プロセスの安定性、各種パラメータの設定の煩雑さ、そしてなにより形成速度の低さから、量産性や生産性の上で大きな問題を抱えている。また、高密度化のためには、磁気ディスク表面を浮上する磁気ヘッドの浮上高さ（フライングハイト）を極力低くする必要があり、垂直二層式磁気記録媒体の製造において、研磨による平坦化加工が可能な厚膜の金属膜を被覆する必要が生じているが、ドライプロセスにより得られた厚膜皮膜は密着性が低く、研磨による平坦化加工が非常に困難であった。そこで、真空蒸着に比べ厚膜化が容易なメッキ法により、非磁性基板に金属膜を被覆する試みが種々検討されている。 Compared to forming a nonmagnetic Cr-based underlayer in a horizontal recording medium, it is not easy to form a soft magnetic backing layer in a vertical two-layer recording medium. Normally, each layer of the horizontal recording medium is formed by a dry process (mainly magnetron sputtering) (Patent Document 1). Various methods for forming not only a recording layer but also a soft magnetic layer by a dry process have been studied in a perpendicular double-layer recording medium. However, the production of a soft magnetic layer by a dry process has major problems in terms of mass productivity and productivity due to process stability, complicated setting of various parameters, and low formation speed. In order to increase the density, it is necessary to reduce the flying height of the magnetic head that floats on the surface of the magnetic disk as much as possible. However, a thick film obtained by a dry process has low adhesion, and flattening by polishing is very difficult. Therefore, various attempts have been made to coat a nonmagnetic substrate with a metal film by a plating method that is easy to increase in thickness compared to vacuum deposition.
垂直二層式磁気記録媒体用の軟磁性層をメッキ法により成膜した場合、軟磁性層を構成するメッキ膜面の数ｍｍから数ｃｍの範囲にわたり特定の方向に磁性を帯びた磁区が多数発生し、それら磁区の界面には磁壁が発生する。このような磁壁を有する軟磁性層を垂直二層式磁気記録媒体用に用いた場合、磁壁部分より発生する漏れ磁界によりスパイクノイズと呼ばれる孤立パルスノイズが発生し信号再生特性が大きく損なわれるという問題がある。 When a soft magnetic layer for a perpendicular double-layer magnetic recording medium is formed by plating, there are many magnetic domains that are magnetized in a specific direction over a range of several mm to several cm of the plated film surface constituting the soft magnetic layer. And domain walls are generated at the interface between the magnetic domains. When a soft magnetic layer having such a domain wall is used for a perpendicular double-layer type magnetic recording medium, a problem of isolated signal noise called spike noise due to a leakage magnetic field generated from the domain wall portion, which greatly impairs the signal reproduction characteristics. There is.
本発明者らは、簡便な方法にて優れた特性を有する垂直二層式磁気記録媒体を得るべく、メッキ法により軟磁性層を形成する条件並びに適用可能な軟磁性層の種類について鋭意研究を重ねた。
その結果、記録媒体を形成する基板の上に、無電解メッキ法にてＣｏとＮｉとＦｅからなる一群から選ばれる２種以上の金属からなる合金を用い軟磁性層を形成する際、その層と平行な面における保磁力が２０エルステッド（Ｏｅ）未満、さらに飽和磁化と残留磁化の比率が４：１から４：３の範囲となるような軟磁性を媒体に用いると、スパイクノイズの発生及びその原因となる磁壁の発生抑止に極めて有効であるとの知見を得た。
また、このようなメッキ層において基板面と垂直な方向の飽和磁化と残留磁化の比率が１００００：１から１００：１とすると一層の磁壁発生がより一層抑止され非常に好ましいことを見出した。
さらに、このような軟磁性膜を得るため、メッキ条件についての詳細な検討を行い、基板上へのメッキ成膜速度と被メッキ基板表面のメッキ液速度の比率を１：３×１０6以上 、１：２×１０8未満となるよう被メッキ基板を自公転させれば良いことを見い出し本発明を完成するに至った。
In order to obtain a perpendicular double-layer magnetic recording medium having excellent characteristics by a simple method, the present inventors have intensively studied the conditions for forming a soft magnetic layer by plating and the types of applicable soft magnetic layers. Piled up.
As a result, when a soft magnetic layer is formed on a substrate on which a recording medium is formed using an alloy of two or more metals selected from the group consisting of Co, Ni, and Fe by an electroless plating method, If soft magnetism such that the coercive force in the plane parallel to the surface is less than 20 Oersted (Oe) and the ratio of saturation magnetization to residual magnetization is in the range of 4: 1 to 4: 3 is used for the medium, spike noise is generated. The knowledge that it was extremely effective in suppressing the occurrence of the domain wall that caused the problem was obtained.
Further, it has been found that when the ratio of saturation magnetization and remanent magnetization in the direction perpendicular to the substrate surface is 10000: 1 to 100: 1 in such a plated layer, the generation of one domain wall is further suppressed, which is very preferable.
Furthermore, in order to obtain such a soft magnetic film, detailed examination of the plating conditions is performed, and the ratio of the plating film formation rate on the substrate and the plating solution rate on the surface of the substrate to be plated is 1: 3 × 10 6 or more. It has been found that the substrate to be plated may be rotated and revolved so that it becomes less than 1: 2 × 10 8, and the present invention has been completed.
即ち、本発明は、直径９０ｍｍ以下の基板と、該基板の上に設けられＣｏとＮｉとＦｅとからなる一群から選ばれる少なくとも２つ以上の金属の合金である軟磁性膜メッキ層とを含んでなる磁気記録媒体用基板において、該軟磁性層が基板面と平行な方向において２０エルステッド（Ｏｅ）未満の保磁力を有し、かつその基板面と平行な方向における磁力飽和磁化と残留磁化の比率が４：１から４：３である磁気記録媒体用基板を提供する。
また、本発明は、直径９０ｍｍ以下の基板の上に、無電解メッキ法を用いて、ＣｏとＮｉとＦｅとからなる一群から選ばれる二以上の金属の合金からなる軟磁性膜を設ける磁気記録媒体用基板の製造方法であって、該無電解メッキ法が、メッキ成膜速度が０．０３μｍ／ｍｉｎ以上０．３μｍ／ｍｉｎ未満となる条件下で、該基板上へメッキ成膜速度と被メッキ基板表面のメッキ液速度の比率を１：３×１０6以上 、１：２×１０8未満となるように、メッキ中に基板を自公転させて被覆することを含む磁気記録媒体用基板の製造方法を提供する。
さらに、本発明は、この磁気記録媒体用基板を用いた磁気記録媒体を提供する。
That is, the present invention includes a substrate having a diameter of 90 mm or less, and a soft magnetic film plating layer that is an alloy of at least two metals selected from the group consisting of Co, Ni, and Fe provided on the substrate. In the magnetic recording medium substrate, the soft magnetic layer has a coercive force of less than 20 Oersted (Oe) in the direction parallel to the substrate surface, and the magnetic saturation magnetization and residual magnetization in the direction parallel to the substrate surface. A magnetic recording medium substrate having a ratio of 4: 1 to 4: 3 is provided.
The present invention also provides a magnetic recording in which a soft magnetic film made of an alloy of two or more metals selected from the group consisting of Co, Ni and Fe is formed on a substrate having a diameter of 90 mm or less using an electroless plating method. A method of manufacturing a substrate for a medium, wherein the electroless plating method includes a plating film formation rate and a coating rate on the substrate under a condition that the plating film formation rate is 0.03 μm / min or more and less than 0.3 μm / min. A substrate for a magnetic recording medium including coating the substrate by revolving during plating so that the ratio of the plating solution speed on the surface of the plating substrate is 1: 3 × 10 6 or more and less than 1: 2 × 10 8 . A manufacturing method is provided.
Furthermore, the present invention provides a magnetic recording medium using this magnetic recording medium substrate.
本発明の軟磁性メッキを適用した磁気記録媒体用基板は、表面の磁壁発生が極めて少なく良好なスパイクノイズ特性を有する。これを垂直磁気記録装置に用いることで、良好なノイズ特性即ち高記録密度を得ることが可能となる。加えて、本発明においては、軟磁性層を湿式の無電解置換メッキにより成膜するため、蒸着法等による下地層の導入に比べてプロセスが大変簡便であり生産性に優れている。さらに、この軟磁性層製造工程は、メッキ後の研磨によりその平滑性が保証することが可能であり、磁気記録媒体として極めて優れた特性を有する。 The substrate for a magnetic recording medium to which the soft magnetic plating of the present invention is applied has excellent spike noise characteristics with extremely few surface domain walls. By using this in a perpendicular magnetic recording apparatus, it is possible to obtain good noise characteristics, that is, high recording density. In addition, in the present invention, since the soft magnetic layer is formed by wet electroless displacement plating, the process is very simple and the productivity is superior to the introduction of the underlayer by vapor deposition or the like. Furthermore, this soft magnetic layer manufacturing process can guarantee smoothness by polishing after plating, and has extremely excellent characteristics as a magnetic recording medium.
本発明に用いる基板は、非磁性基板であれば特に限定されないが、従来より磁気記録媒体の製造に用いられているアルミ基板にＮｉ−Ｐ無電解メッキを施した基板、ガラス基板の他、単結晶ＳｉよりなるＳｉ基板を用いることが出来る。 The substrate used in the present invention is not particularly limited as long as it is a non-magnetic substrate. However, in addition to a substrate obtained by performing Ni-P electroless plating on an aluminum substrate conventionally used for manufacturing a magnetic recording medium, a glass substrate, a single substrate. A Si substrate made of crystalline Si can be used.
Ｓｉ単結晶基板は、置換メッキが可能であり、また極めて均質な特性を有している関係から、メッキ不均一に起因する磁気的な不均一を抑制出来る点で本発明を履行する上で特に好ましい。
Ｓｉ基板に用いられるＳｉ単結晶としては、ＣＺ（チョコラルスキー）法或いはＦＺ（フローティングゾーン）法により製造されたＳｉ単結晶材が特に好ましい。基板の面方位は、（１００）、（１１０）、（１１１）を初めとして任意のものを用いればよい。また、基板中の不純物としては、０〜１０22ａｔｏｍｓ／ｃｍ2の合計量の範囲のＢ、Ｐ、Ｎ、Ａｓ、Ｓｎ等の元素を含有しても良い。但し、基板の同一平面において面方位の異なる多結晶Ｓｉ、及び極度に不純物の偏析のあるＳｉを基板として用いた場合には、その化学反応性の違いにより形成される下地メッキ層が不均一となってしまう場合がある。さらに、極端な偏析のある基板を使用した場合には、下地メッキ層成膜中に基板表面の偏析部位に局部電池が形成されてしまうことで、下地メッキ層構造の達成が不能となることもある。
Since the Si single crystal substrate is capable of displacement plating and has a very homogeneous characteristic, it is particularly preferable to implement the present invention in that magnetic non-uniformity caused by non-uniform plating can be suppressed. preferable.
As the Si single crystal used for the Si substrate, a Si single crystal material manufactured by the CZ (chocolate ski) method or the FZ (floating zone) method is particularly preferable. Any plane orientation of the substrate may be used, including (100), (110), and (111). Further, the impurities in the substrate may contain elements such as B, P, N, As, and Sn in the total amount range of 0 to 10 22 atoms / cm 2 . However, when polycrystalline Si having different plane orientations on the same plane of the substrate and Si having extremely segregated impurities are used as the substrate, the underlying plating layer formed due to the difference in chemical reactivity is not uniform. It may become. Furthermore, when a substrate with extreme segregation is used, a local battery may be formed at the segregation site on the substrate surface during the formation of the base plating layer, making it impossible to achieve the base plating layer structure. is there.
本発明において基板材料にＳｉを用いる場合には、好ましくは、その表面酸化膜及び基板表面を僅かにエッチングすることで、下地メッキ層形成に必要な活性化を行う。
エッチングは、酸、アルカリ又は電解と種々の方法を選択することが可能である。エッチングの条件については、例えば苛性ソーダ等のアルカリ水溶液を用いる場合には、濃度２〜６０重量％、３０〜１００℃液中でエッチングし、表面の酸化膜除去を行うと共に基板表面を僅かに腐食させる。
その後、好ましくは密着性を得るための置換メッキ、そして軟磁性層の無電解メッキを順次施す。
In the present invention, when Si is used as the substrate material, the surface oxide film and the substrate surface are preferably etched slightly to activate the base plating layer.
For etching, various methods such as acid, alkali, or electrolysis can be selected. As for the etching conditions, for example, when an alkaline aqueous solution such as caustic soda is used, etching is performed in a liquid at a concentration of 2 to 60% by weight and 30 to 100 ° C. to remove the oxide film on the surface and slightly corrode the substrate surface. .
Thereafter, preferably, replacement plating for obtaining adhesion and electroless plating of the soft magnetic layer are sequentially performed.
置換メッキは、エッチング処理を行った後に、Ａｇ、Ｃｏ、Ｃｕ、Ｎｉ、Ｐｄ、及びＰｔからなる一群から選ばれる一以上の金属イオン又はこれらを主な金属イオンとして元素成分で０．０１Ｎ以上、好ましくは０．０５〜０．３Ｎ含有するメッキ液に浸漬することで、基板表面のＳｉ原子と金属原子を置換させメッキ膜を得るものである。置換メッキの方法としては、特に限定されず、公知のメッキの方法を用いることができる。
置換メッキ層の厚さは、１０〜１０００ｎｍが好ましく、更に好ましくは、５０〜５００ｎｍである。１０ｎｍより小さいと、金属多結晶の粒個々の均一な層内での分布が得られない場合があり、１０００ｎｍを超えると個々の結晶粒が肥大化してしまい下地層として好ましくない場合がある。
Substitution plating, after performing the etching process, one or more metal ions selected from the group consisting of Ag, Co, Cu, Ni, Pd, and Pt or 0.01N or more as an element component using these as main metal ions, Preferably, the plating film is obtained by immersing in a plating solution containing 0.05 to 0.3 N to replace Si atoms and metal atoms on the substrate surface. The displacement plating method is not particularly limited, and a known plating method can be used.
The thickness of the displacement plating layer is preferably 10 to 1000 nm, and more preferably 50 to 500 nm. When the thickness is smaller than 10 nm, the distribution of the metal polycrystal grains in the individual uniform layer may not be obtained. When the thickness exceeds 1000 nm, the individual crystal grains may be enlarged, which may not be preferable as the underlayer.
本発明の最大の特徴は、磁気記録媒体を製造するに当たり、軟磁性層として、基板面と平行な方向において、２０ Ｏｅ未満、好ましくは２〜５ Ｏｅの保磁力を有し、かつ磁力飽和磁化と残留磁化の比率が４：１から４：３、さらに好ましくは軟磁性メッキ膜の基板面と垂直な方向の飽和磁化と残留磁化の比率が１００：１から１００００：１となる無電解メッキ膜を用いる点にある。 The greatest feature of the present invention is that, in producing a magnetic recording medium, the soft magnetic layer has a coercive force of less than 20 Oe, preferably 2 to 5 Oe, in a direction parallel to the substrate surface, and a magnetic saturation magnetization. And remanent magnetization ratio of 4: 1 to 4: 3, more preferably, the ratio of saturation magnetization and remanent magnetization in the direction perpendicular to the substrate surface of the soft magnetic plating film is 100: 1 to 10,000: 1. The point is to use.
軟磁性メッキ層形成は、一般に無電解置換メッキとして知られる方法にて成膜を行う 。
電解メッキには、硫化物浴又は塩化物浴の何れを用いることも可能であり、また、その浴中金属としても種々のものを用いることが可能であるが、軟磁性層としての磁気特性を発現させ、なおかつ立方晶の結晶を得る必要からＣｏとＮｉとＦｅとから選ばれる元素を含有する金属塩を用い、これらの元素のうち２種以上元素を含有する合金メッキ層を形成させる必要がある。
The soft magnetic plating layer is formed by a method generally known as electroless displacement plating.
For electroplating, either a sulfide bath or a chloride bath can be used, and various metals can be used in the bath, but the magnetic properties as a soft magnetic layer can be improved. It is necessary to form a metal plating layer containing an element selected from Co, Ni, and Fe, and to form an alloy plating layer containing two or more of these elements, because it is necessary to obtain a cubic crystal. is there.
Ｃｏ、Ｎｉ、Ｆｅは、無電解メッキが可能であり、かつ軟磁性材料としての良好な特性を有している関係から、本発明の実施に当ってはこれらの元素を含有することが必要である。
また、本発明の磁気特性は、極めて微細な領域での主成分金属の偏析に起因していると推定されるため、その実施に当ってはこれらの金属成分を２種以上含有する合金メッキ層としてやる必要がある。一方、金属単体のメッキ層においては、本発明の効果を得ることが困難である。
Co, Ni, and Fe can be electrolessly plated and have good characteristics as a soft magnetic material. Therefore, it is necessary to contain these elements in the practice of the present invention. is there.
In addition, since the magnetic properties of the present invention are presumed to be due to segregation of the main component metal in a very fine region, an alloy plating layer containing two or more of these metal components is required in the implementation. It is necessary to do as. On the other hand, it is difficult to obtain the effect of the present invention in the plating layer of a single metal.
具体的な浴組成としては、硫酸ニッケル、硫酸コバルト混合浴等が挙げられ、この時の好ましい濃度は、０．０１〜０．５Ｎである。
無電解メッキにおける還元剤としては、ジア燐酸、ジメチルアミンボランを初めとし浴、或いは浴を構成する金属イオンに応じ種々のものを用いることが出来る。
Specific examples of the bath composition include nickel sulfate and cobalt sulfate mixed baths, and the preferred concentration at this time is 0.01 to 0.5N.
As a reducing agent in electroless plating, various materials such as diaphosphoric acid and dimethylamine borane can be used depending on the bath or the metal ions constituting the bath.
本発明に必要とされるメッキ軟磁性層は、無電解メッキを行う際、基板上へのメッキ成膜速度と被メッキ基板表面のメッキ液速度の比率を１：３×１０6以上、１：２×１０8未満、好ましくは１：８×１０6から１：１．５×１０8となるようメッキ中に基板を自公転させることで得ることが出来る。
基板上へのメッキ成膜速度と被メッキ基板表面のメッキ液速度の比率が１：３×１０6未満の場合は、回転数については本発明で規定する飽和磁化と残留磁化の比率＝４：３より残留磁化が大きくなり過ぎる。基板上へのメッキ成膜速度と被メッキ基板表面のメッキ液速度の比率が１：２×１０8を超えると、飽和磁化と残留磁化の比率が本発明で規定する４：１より小さくなり過ぎるのみならずメッキに付きムラが生ずるため好ましくない。
In the plated soft magnetic layer required for the present invention, the ratio of the plating film formation rate on the substrate and the plating solution rate on the surface of the substrate to be plated is 1: 3 × 10 6 or more, 1: It can be obtained by revolving the substrate during plating so that it is less than 2 × 10 8 , preferably 1: 8 × 10 6 to 1: 1.5 × 10 8 .
When the ratio of the plating film formation speed on the substrate and the plating solution speed on the surface of the substrate to be plated is less than 1: 3 × 10 6 , the ratio of the saturation magnetization and the residual magnetization defined in the present invention for the rotational speed = 4: 3, the residual magnetization becomes too large. When the ratio of the plating film formation rate on the substrate and the plating solution rate on the surface of the substrate to be plated exceeds 1: 2 × 10 8 , the ratio of the saturation magnetization to the residual magnetization becomes too smaller than 4: 1 defined in the present invention. Not only that, but also non-uniformity occurs in the plating.
この際、メッキ成膜速度自体も、前記比率と同様本発明具現のための重要な因子となり、０．０３μｍ／ｍｉｎ以上０．３μｍ／ｍｉｎ未満、好ましくは０．２μｍ／ｍｉｎ以上となる条件下にて達成が可能となる。
メッキ成膜速度が０．０３μｍ／ｍｉｎ未満の場合には、どのような組成、メッキ条件においても２０ Ｏｅ未満の保磁力を得ることは困難であり、さらに、残留磁化が大きくなり過ぎて本発明具現に好ましい基板面と垂直な方向の飽和磁化と残留磁化の比率４：３を超えてしまう。
一方、メッキ成膜速度が０．３μｍ／ｍｉｎを超えると、結晶構成粒子がアモルファス化してしまうことで残留磁化が小さくなり過ぎ、基板面と垂直な方向の飽和磁化と残留磁化の比率が、本発明具現に好ましい比率である４：１より小さくなりすぎてしまう。
At this time, the plating film forming rate itself is an important factor for embodying the present invention, as is the case with the above-described ratio, and is a condition of 0.03 μm / min or more and less than 0.3 μm / min, preferably 0.2 μm / min or more. Can be achieved.
When the plating film forming speed is less than 0.03 μm / min, it is difficult to obtain a coercive force of less than 20 Oe in any composition and plating condition, and the residual magnetization becomes too large. The ratio of saturation magnetization and remanent magnetization in the direction perpendicular to the substrate surface preferable for implementation exceeds 4: 3.
On the other hand, if the plating film formation speed exceeds 0.3 μm / min, the crystallographic particles become amorphous, and the residual magnetization becomes too small. The ratio of saturation magnetization and residual magnetization in the direction perpendicular to the substrate surface is The ratio is too smaller than 4: 1 which is a preferable ratio for realizing the invention.
所定のメッキ液流速を得る方法としては、メッキ時の液循環を調整する、パドル等の攪拌子を用いてメッキ液を攪拌する、基板を自、公転させる方法が考えられる。
中でも基板を自公転させる方法は、所定の液流速を得るには簡便かつ効果的な方法で有り好ましいが、基板が大径の場合には基板面に渦流が発生しやすい。
本発明において基板の寸法を９０ｍｍ以下としたのは、この寸法以上においては基板面に均一なメッキ液の流れを形成するのが困難で有り、本発明の具現が困難であるためである。
As a method for obtaining a predetermined plating solution flow rate, a method of adjusting the solution circulation during plating, agitating the plating solution using a stirrer such as a paddle, or revolving the substrate itself can be considered.
Among them, the method of rotating and revolving the substrate is preferable because it is a simple and effective method for obtaining a predetermined liquid flow rate. However, when the substrate has a large diameter, eddy current tends to be generated on the substrate surface.
The reason why the size of the substrate is set to 90 mm or less in the present invention is that it is difficult to form a uniform plating solution flow on the substrate surface above this size, and it is difficult to implement the present invention.
本発明でいう所のメッキ成膜速度とは、単位時間当たりのメッキ膜の成長厚みであり、メッキ膜の断面を走査電子顕微鏡で調べること、或いは蛍光Ｘ線分析等により調べることが出来る。 The plating film formation rate referred to in the present invention is the growth thickness of the plating film per unit time, and can be examined by examining the cross section of the plating film with a scanning electron microscope or fluorescent X-ray analysis.
本発明で言う所のメッキ液速度とは、被メッキ基板面に平行な方向のメッキ液と基板との相対速度であり、特に基板表面より１０ｍｍ未満の領域のメッキ液と基板との相対速度のことでありピトー管式流速計の他、羽根車式の質量流量計、超音波流量計、レーザードップラ流速計により得られる該領域のメッキ液流速と被メッキ基板の動きの差として計測することが出来る。
被メッキ基板の近傍１ｍｍ未満の領域には、液境膜と呼ばれる粘性によりメッキ面に半固着した状態で動くメッキ液の滞留流体層があるが、本発明で言う所のメッキ液流速は液境膜領域のごとき数値測定が困難な基板直近部分の流速を勘案したものでは無い。
The plating solution speed referred to in the present invention is the relative speed between the plating solution and the substrate in the direction parallel to the surface of the substrate to be plated, and in particular, the relative speed between the plating solution and the substrate in a region less than 10 mm from the substrate surface. It can be measured as the difference between the plating solution flow rate and the movement of the substrate to be plated obtained by an impeller type mass flow meter, ultrasonic flow meter, laser Doppler velocimeter as well as Pitot tube type flow meter. I can do it.
In a region less than 1 mm in the vicinity of the substrate to be plated, there is a staying fluid layer of a plating solution that moves in a state of being semi-adhered to the plating surface due to the viscosity called a liquid boundary film. This does not take into consideration the flow velocity in the immediate vicinity of the substrate, which is difficult to measure numerically, such as in the membrane region.
このような本発明で規定の特性を有する軟磁性層についてその結晶構造をＸ線回折により調べた。その結果、本発明に該当する軟磁性層の結晶配列は、組成の如何にかかわらず、その何れもがＦＣＣ又はＢＣＣの立方系の結晶構造を有している。結晶の方形面を形成する部分の格子面の間隔を比べると、軟磁性層平面と垂直な方向の格子面間隔と層平面と平行な方向の面間隔を比べた場合、軟磁性層と垂直な方向の立方格子面が０．３％以上３％未満長いという格子面間隔の差異が見出された。また、このような格子面間隔の差異は、軟磁性層を構成する結晶の方位、配向度には依存せず、層平表面に対する角度に依存していることも見出された。詳細な理由は不明であるが、本発明の記載の軟磁性層の磁気特性はこのような内部結晶構造に起因していると推定される。 The crystal structure of the soft magnetic layer having the characteristics specified in the present invention was examined by X-ray diffraction. As a result, the crystal arrangement of the soft magnetic layer corresponding to the present invention has an FCC or BCC cubic crystal structure regardless of the composition. Comparing the spacing of the lattice planes of the portion forming the square surface of the crystal, when comparing the lattice spacing in the direction perpendicular to the plane of the soft magnetic layer and the plane spacing in the direction parallel to the layer plane, it is perpendicular to the soft magnetic layer. A difference in lattice spacing was found that the cubic lattice plane in the direction was longer than 0.3% and less than 3%. It has also been found that such a difference in lattice spacing does not depend on the orientation and degree of orientation of the crystals constituting the soft magnetic layer but on the angle with respect to the plane surface of the layer. Although the detailed reason is unknown, it is presumed that the magnetic properties of the soft magnetic layer described in the present invention are caused by such an internal crystal structure.
軟磁性層の厚みは、好ましくは１００〜１０００ｎｍである。
１０００ｎｍを超えると、媒体として信号再生時の軟磁性層よりの磁気ノイズが大きくなり、媒体としてのＳ／Ｎが特性の低下をまねき好ましくない。一方、厚みが１００ｎｍ未満では、軟磁性下地としての磁気透過特性不十分で有り媒体としてのオーバーライト特性が低下するため好ましくない。
The thickness of the soft magnetic layer is preferably 100 to 1000 nm.
If it exceeds 1000 nm, magnetic noise from the soft magnetic layer at the time of signal reproduction as a medium becomes large, and the S / N as the medium is not preferable because it leads to deterioration of characteristics. On the other hand, if the thickness is less than 100 nm, the magnetic transmission characteristics as a soft magnetic underlayer are insufficient, and the overwrite characteristics as a medium are deteriorated.
本発明の磁気記録媒体は、以上のような軟磁性層を１００〜１０００ｎｍ形成した後、好ましくは、上層に５〜１００ｎｍの磁気記録層、２〜２０ｎｍ保護層、潤滑層を順次形成することで具現化される。
磁気記録層は、軟磁性層の上に形成され、磁気記録を行うための硬磁性材料よりなる記録層である。
磁気記録層は、軟磁性層の直上に形成しても良いが、必要に応じ結晶粒径及び磁気特性の整合を取るための種々のＴｉを初めとする中間層を１層以上介しても良い。
磁気記録層としては層平面に垂直な方向に磁化容易磁区を有する高磁性材料で有れば
特に制限は無く、スパッタ法によるＣｏ−Ｃｒ合金膜、Ｆｅ−Ｐｔ合金膜を初めＣｏ−Ｓｉグラニュール膜、Ｃｏ／Ｐｄ多層膜等種々のものを用いることが出来る。また、湿式法により形成される膜、例えばＣｏ−Ｎｉ系メッキ膜さらには塗布による記録層としてマグネトプランバイト相よりなるバリウム・フェライトを塗布して記録層としても良い。
このような記録層の厚みは、概ね５〜１００ｎｍ、さらに好ましくは１０〜５０ｎｍの範囲が好ましい。また、保磁力に関しては０．５〜１０ＫＯｅさらに好ましくは１．５〜３．５ＫＯｅのものが良い。
In the magnetic recording medium of the present invention, the soft magnetic layer as described above is formed to a thickness of 100 to 1000 nm, and preferably a 5 to 100 nm magnetic recording layer, a 2 to 20 nm protective layer, and a lubricating layer are sequentially formed on the upper layer. Embodied.
The magnetic recording layer is a recording layer formed on a soft magnetic layer and made of a hard magnetic material for performing magnetic recording.
The magnetic recording layer may be formed immediately above the soft magnetic layer, but if necessary, one or more intermediate layers including various Tis for matching the crystal grain size and magnetic characteristics may be interposed. .
The magnetic recording layer is not particularly limited as long as it is a high magnetic material having an easy magnetic domain in a direction perpendicular to the plane of the layer, and includes a Co—Cr alloy film, an Fe—Pt alloy film by sputtering, and a Co—Si granule. Various films such as a film and a Co / Pd multilayer film can be used. A recording layer may be formed by applying a film formed by a wet method, for example, a Co—Ni plating film, or a recording layer by coating with barium / ferrite composed of a magnetoplumbite phase.
The thickness of such a recording layer is generally in the range of 5 to 100 nm, more preferably 10 to 50 nm. Further, the coercive force is preferably 0.5 to 10 KOe, more preferably 1.5 to 3.5 KOe.
磁気記録層の上層に形成される保護層は、スパッタ法、ＣＶＤ法により形成される非晶質Ｃ系の保護膜を初めとしてＡｌ2Ｏ3等の結晶性の保護膜を用いることが出来る。 As the protective layer formed on the magnetic recording layer, a crystalline protective film such as Al 2 O 3 as well as an amorphous C-based protective film formed by sputtering or CVD can be used.
さらに最上層の潤滑膜は、フッ素系油脂を塗布することで単分子膜を形成したものを用いてやれば良く、その剤種及び塗布方法については特に制限は無い。 Further, the uppermost lubricating film may be formed by applying a monomolecular film by applying a fluorinated oil and fat, and there are no particular restrictions on the type of agent and the application method.
以下本発明を例に基づき説明するが、本発明はこれに限定されるものではない。
実施例１
ＣＺ法で製作した直径２００ｍｍのＳｉ単結晶基板から、コア抜き・芯取り・ラップを行い、直径６５ｍｍの（１００）Ｓｉ単結晶（ＰドープのＮ型基板）を得た後、平均粒径１５ｎｍのコロイダルシリカにより両面研磨し、表面粗さ（Ｒｍｓ）４ｎｍを得た。Ｒｍｓは平方平均粗さであり、ＡＦＭ（原子間力顕微鏡）を用いて測定した。
この基板を４５℃、２重量％の苛性ソーダ水溶液に３分間浸漬して基板表面の薄い表面酸化膜を除去すると共に表面のＳｉエッチング処理を行い、続いて０．１Ｎの硫酸ニッケル水溶液に硫酸アンモニウムを０．５Ｎ添加した下地メッキ浴を製作し８０℃に加熱した浴中でに５分間浸漬して下地メッキ層を得た。
Hereinafter, the present invention will be described based on examples, but the present invention is not limited thereto.
Example 1
Core removal, centering, and lapping were performed from a 200 mm diameter Si single crystal substrate manufactured by the CZ method to obtain a 65 mm diameter (100) Si single crystal (P-doped N-type substrate), and then an average particle size of 15 nm. Both surfaces were polished with colloidal silica to obtain a surface roughness (Rms) of 4 nm. Rms is the mean square roughness, measured using an AFM (Atomic Force Microscope).
This substrate was immersed in a 2% by weight aqueous caustic soda solution at 45 ° C. for 3 minutes to remove the thin surface oxide film on the surface of the substrate and to perform Si etching treatment on the surface. Subsequently, 0% ammonium sulfate was added to the 0.1N nickel sulfate aqueous solution. A base plating bath with 5N added was prepared and immersed in a bath heated to 80 ° C. for 5 minutes to obtain a base plating layer.
さらに、この基板を、硫酸アンモニウム０．２Ｎと、硫酸ニッケル０．０２Ｎと、硫酸コバルト０．１Ｎと、硫酸鉄０．０１Ｎと、還元剤としてジメチルアミンボラン０．０４Ｎを含むメッキ液を建浴し、無電解メッキの膜成長速度０．１μｍ／ｍｉｎとなるよう浴温を６５℃に設定した。
このメッキ液に回転数６０ｒｐｍにて被メッキ基板を高速で自転させつつ２０分の無電解メッキを行い厚み２μｍの軟磁性層を得た。
この時のメッキ面におけるメッキ液の速度を基板面から５ｍｍの位置でレーザードプラー流速計にて計測した所、基板の内周部の半径１０ｍｍの位置で基板に対して３０００ｍｍ／ｍｉｎ、また、最外周部の半径３２．５ｍｍの位置で基板に対して１００００ｍｍ／ｍｉｎとなり、メッキ成膜速度と被メッキ基板表面のメッキ液流速の比率でそれぞれ１：３×１０7、１：１０8の値であった。
Further, this substrate was bathed with a plating solution containing ammonium sulfate 0.2N, nickel sulfate 0.02N, cobalt sulfate 0.1N, iron sulfate 0.01N, and dimethylamine borane 0.04N as a reducing agent. The bath temperature was set to 65 ° C. so that the film growth rate of electroless plating was 0.1 μm / min.
The plating solution was subjected to electroless plating for 20 minutes while rotating the substrate to be plated at a high speed of 60 rpm to obtain a soft magnetic layer having a thickness of 2 μm.
When the speed of the plating solution on the plating surface at this time was measured with a laser Doppler velocimeter at a position 5 mm from the substrate surface, it was 3000 mm / min with respect to the substrate at a radius of 10 mm at the inner peripheral portion of the substrate. 10000 mm / min next to the substrate at the position of the radius 32.5mm of the outer peripheral portion, respectively at a ratio of plating solution flow rate of plating deposition rate and the substrate to be plated surface 1: 3 × 10 7, 1 : a value of 10 8 there were.
このようにして得られた軟磁性膜の磁気特性を振動型磁力計で計測したところ、軟磁性層面に平行な方向の保磁力は４エルステッド（Ｏｅ)、飽和磁化は１８０００Ｇ残留磁化は９０００Ｇとなり磁力飽和磁化と残留磁化の比率は２：１であった。
また、同様に磁性層面に垂直な方向の磁気特性を計測したところ、保磁力５０ Ｏｅ、飽和磁化は１８０００Ｇ残留磁化は１０Ｇとなり磁力飽和磁化と残留磁化の比率は１８００：１であった。
さらに、Ｘ線回折法により軟磁性層の結晶を観察したところ、無配向のＦＣＣ結晶群から構成され膜面と平行な方向の格子面間隔の平均が２．０２４Ａ、膜面と垂直な方向の立方格面間隔の平均が２．０４０Ａであり、膜面と垂直な方向の格子面間隔が膜面と平行な方向の立方格子面間隔より０．８％長かった。
When the magnetic properties of the soft magnetic film thus obtained were measured with a vibration type magnetometer, the coercive force in the direction parallel to the surface of the soft magnetic layer was 4 Oersted (Oe), the saturation magnetization was 18000 G, and the residual magnetization was 9000 G. The ratio of saturation magnetization to residual magnetization was 2: 1.
Similarly, when the magnetic characteristics in the direction perpendicular to the magnetic layer surface were measured, the coercive force was 50 Oe, the saturation magnetization was 18000 G, the residual magnetization was 10 G, and the ratio of the magnetic saturation magnetization to the residual magnetization was 1800: 1.
Further, when the crystal of the soft magnetic layer was observed by the X-ray diffraction method, the average lattice spacing in the direction parallel to the film surface composed of non-oriented FCC crystal group was 2.024A, and the direction perpendicular to the film surface was The average cubic spacing was 2.040 A, and the lattice spacing in the direction perpendicular to the film surface was 0.8% longer than the cubic lattice spacing in the direction parallel to the film surface.
このような軟磁性層付き基板面に、スパッタ法により２２０℃の温度を維持しつつＣｏ：Ｃｒ：Ｔａ＝７９：１９：２重量％となる厚み２０ｎｍの垂直磁気記録膜を被覆した。
この記録層の保磁力を計測したところ、膜面と垂直な方向の保磁力は２．２ＫＯｅ、また、膜面と平行な方向の保磁力は５００エルステッド（Ｏｅ）であった。
A surface of such a substrate with a soft magnetic layer was coated with a perpendicular magnetic recording film having a thickness of 20 nm so that Co: Cr: Ta = 79: 19: 2 wt% while maintaining a temperature of 220 ° C. by sputtering.
When the coercivity of the recording layer was measured, the coercivity in the direction perpendicular to the film surface was 2.2 KOe, and the coercivity in the direction parallel to the film surface was 500 Oersted (Oe).
さらに、この基板上に厚み１０ｎｍのアモルファスカーボンを被覆しディップ法によりフッ素潤滑膜を塗布して垂直磁気記録媒体を得た。
得られた媒体をスピンスタンドに設置しＤＣイレーズを実施後、浮上高１０ｎｍのナノスライダーＧＭＲヘッドにより媒体のノイズ測定を行った結果、再生エンベローブパターン中にスパイクノイズは見いだされなかった。
また、磁気転移状態を調べるため、磁気検査装置（ｃａｎｄｅｌａ社ＯＳＡ５１００）にて基板面全域Ｋｅｒｒ効果像を調べたが軟磁性膜起因のスパイクノイズの原因となるような磁化転移は見出されなかった。
Further, this substrate was coated with amorphous carbon having a thickness of 10 nm, and a fluorine lubricating film was applied by a dip method to obtain a perpendicular magnetic recording medium.
After the obtained medium was placed on a spin stand and subjected to DC erase, the noise of the medium was measured with a nano slider GMR head having a flying height of 10 nm. As a result, no spike noise was found in the reproduction envelope pattern.
Further, in order to investigate the magnetic transition state, the Kerr effect image of the entire substrate surface was examined with a magnetic inspection device (Candela OSA5100), but no magnetization transition that caused spike noise caused by the soft magnetic film was found. .
Claims (5)
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| JP2004265690A JP2005108407A (en) | 2003-09-12 | 2004-09-13 | Magnetic recording medium and substrate for magnetic recording medium |
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| JP2004265690A JP2005108407A (en) | 2003-09-12 | 2004-09-13 | Magnetic recording medium and substrate for magnetic recording medium |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007177257A (en) * | 2005-12-26 | 2007-07-12 | Seiko Epson Corp | Plating method, plating apparatus, and method for manufacturing silicon device |
| JP2008123633A (en) * | 2006-11-15 | 2008-05-29 | Shin Etsu Chem Co Ltd | Substrate for magnetic recording medium, and magnetic recording medium |
| US7851076B2 (en) | 2007-10-10 | 2010-12-14 | Shin-Etsu Chemical Co., Ltd. | Method of fabricating silicon substrate for magnetic recording media, and magnetic recording medium |
| JP2015203108A (en) * | 2014-04-16 | 2015-11-16 | 株式会社フジミインコーポレーテッド | polishing composition |
-
2004
- 2004-09-13 JP JP2004265690A patent/JP2005108407A/en not_active Withdrawn
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007177257A (en) * | 2005-12-26 | 2007-07-12 | Seiko Epson Corp | Plating method, plating apparatus, and method for manufacturing silicon device |
| JP2008123633A (en) * | 2006-11-15 | 2008-05-29 | Shin Etsu Chem Co Ltd | Substrate for magnetic recording medium, and magnetic recording medium |
| US7851076B2 (en) | 2007-10-10 | 2010-12-14 | Shin-Etsu Chemical Co., Ltd. | Method of fabricating silicon substrate for magnetic recording media, and magnetic recording medium |
| JP2015203108A (en) * | 2014-04-16 | 2015-11-16 | 株式会社フジミインコーポレーテッド | polishing composition |
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