JP2009146532A

JP2009146532A - Perpendicular magnetic recording medium and magnetic storage device

Info

Publication number: JP2009146532A
Application number: JP2007324547A
Authority: JP
Inventors: Hiroyuki Nakagawa; 宏之中川; Ryoko Araki; 亮子荒木; Ikuko Takekuma; 育子武隈
Original assignee: Hitachi Global Storage Technologies Netherlands BV
Current assignee: HGST Netherlands BV
Priority date: 2007-12-17
Filing date: 2007-12-17
Publication date: 2009-07-02

Abstract

<P>PROBLEM TO BE SOLVED: To provide a perpendicular magnetic recording medium which has an excellent S/N and excellent thermal stability with less erasure of adjacent tracks. <P>SOLUTION: The perpendicular magnetic recording medium includes: a base layer formed on a substrate; a granular magnetic layer which includes columnar magnetic particles whose principal components are Co, Cr, and Pt with a hexagonal close-packed structure which has preferred (0001) orientation and oxides and is formed on the base layer; and a ferromagnetic layer formed on the granular magnetic layer without including the oxides. The dispersion of a normalized grain boundary area A_b/A_g+b in the granular magnetic layer is 30% or lower when an area enclosed by a line connecting centroids of the ferromagnetic particles adjacent to a certain ferromagnetic particle in the granular magnetic layer is A_g+b, and an area of the grain boundary included therein is A_b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、大容量の情報を記録可能な垂直磁気記録媒体及びそれを用いた磁気記憶装置に関する。 The present invention relates to a perpendicular magnetic recording medium capable of recording a large amount of information and a magnetic storage device using the same.

近年、コンピュータの扱う情報量が増大し、補助記憶装置としてハードディスク装置の大容量化が一段と求められている。さらに、家庭用の電気製品へのハードディスク装置の搭載が進むことにより、ハードディスク装置の小型化、大容量化の要望は強くなる一方である。 In recent years, the amount of information handled by computers has increased, and there has been a further demand for a large capacity hard disk drive as an auxiliary storage device. Furthermore, with the progress of mounting hard disk devices in household electrical products, the demand for smaller hard disks and larger capacities is increasing.

これまで磁気ディスク装置に用いられていた面内磁気記録方式では、媒体に記録された磁化が互いに逆向きに向き合って隣接するため、線記録密度を高めるには記録層の保磁力を増大させるとともに膜厚を減少させる必要がある。ところが、記録層の保磁力が増大すると記録ヘッドの書き込み能力が不足するという問題が生じ、記録層の膜厚が小さくなると熱減磁により記録情報が失われるという問題が生じ、面内記録方式を用いて記録密度を向上させることが難しくなってきている。これらの問題を解決するため、垂直磁気記録方式を用いた磁気ディスク装置の開発が活発化している。垂直磁気記録方式は、記録媒体の磁化を媒体面に垂直に、かつ隣り合う記録ビット内の磁化が互いに反平行になるように記録ビットを形成する方式であり、面内記録方式に比べて磁化遷移領域での反磁界が小さいため媒体ノイズを低減でき、高密度記録時の記録磁化を安定に保持できる。また、垂直磁気記録媒体と基板との間に磁束のリターンパスとして働く軟磁性下地層を設けた二層垂直磁気記録媒体と単磁極型ヘッド（ＳＰＴヘッドと呼ぶ）とを組み合わせる方式が提案されている。さらに、記録磁界勾配を向上させるために、主磁極のトレーリング側に非磁性のギャップ層を介して磁気シールドを設けた磁気ヘッド（ＴＳヘッドと呼ぶ）が提案されている。 In the in-plane magnetic recording method that has been used in magnetic disk devices so far, the magnetizations recorded on the medium are adjacent to each other in opposite directions. Therefore, in order to increase the linear recording density, the coercive force of the recording layer is increased. It is necessary to reduce the film thickness. However, when the coercive force of the recording layer increases, there arises a problem that the writing ability of the recording head is insufficient, and when the film thickness of the recording layer becomes small, there arises a problem that recorded information is lost due to thermal demagnetization. It has become difficult to improve the recording density by using it. In order to solve these problems, development of a magnetic disk device using a perpendicular magnetic recording system has been activated. The perpendicular magnetic recording method is a method in which recording bits are formed so that the magnetization of the recording medium is perpendicular to the medium surface and the magnetizations in adjacent recording bits are antiparallel to each other. Since the demagnetizing field in the transition region is small, medium noise can be reduced, and the recording magnetization during high-density recording can be stably maintained. In addition, a method has been proposed in which a two-layer perpendicular magnetic recording medium provided with a soft magnetic underlayer serving as a magnetic flux return path between a perpendicular magnetic recording medium and a substrate is combined with a single pole type head (referred to as an SPT head). Yes. Furthermore, in order to improve the recording magnetic field gradient, a magnetic head (referred to as a TS head) in which a magnetic shield is provided on the trailing side of the main pole via a nonmagnetic gap layer has been proposed.

垂直磁気記録媒体の磁気記録層としては、磁性結晶粒の周囲に酸化物や窒化物などの非磁性化合物を偏析させることにより磁性結晶粒を磁気的に分離した構造（グラニュラー構造と呼ぶ）が提案されている。例えば、IEEE Transactions on Magnetics, Vol.40, No.4, July 2004, pp. 2498-2500, “Role of Oxygen Incorporation in Co-Cr-Pt-Si-O Perpendicular Magnetic Recording Media”には、ＣｏＣｒＰｔ合金とＳｉＯ₂を含有する複合型ターゲットを用い、アルゴン酸素混合ガス雰囲気中でＤＣマグネトロンスパッタによりグラニュラー構造を有する記録層を形成する方法が開示されている。 As a magnetic recording layer of a perpendicular magnetic recording medium, a structure in which magnetic crystal grains are magnetically separated by segregating nonmagnetic compounds such as oxides and nitrides around the magnetic crystal grains (called a granular structure) is proposed. Has been. For example, IEEE Transactions on Magnetics, Vol.40, No.4, July 2004, pp. 2498-2500, “Role of Oxygen Incorporation in Co-Cr-Pt-Si-O Perpendicular Magnetic Recording Media” includes CoCrPt alloy and A method of forming a recording layer having a granular structure by DC magnetron sputtering in an argon-oxygen mixed gas atmosphere using a composite target containing SiO ₂ is disclosed.

特開２００５−１９０５５２号公報には、ＳＮＲ向上の方法として、規格化粒界幅分散を４０％以下としたグラニュラー構造を有する垂直磁気記録媒体が開示されている。また、特開２００６−３０２４２６号公報には、媒体の低ノイズ化、ＳＮＲ向上の方法として、Ｃｏ，Ｃｒ，Ｐｔ，Ｓｉ，Ｏを含有し、磁性結晶粒径が膜厚方向に実質的に一定であり、中間層との界面側に表面層よりも酸素の多い領域を有するグラニュラー構造を持った磁気記録層が開示されている。また、特開２００６−１６４４４０号公報には、非磁性粒界を膜厚方向に均等な幅に保ち、強磁性結晶粒子の粒径を均一化、微細化したグラニュラー垂直磁気記録媒体が開示されている。 Japanese Patent Application Laid-Open No. 2005-190552 discloses a perpendicular magnetic recording medium having a granular structure with a normalized grain boundary width dispersion of 40% or less as a method for improving SNR. Japanese Patent Application Laid-Open No. 2006-302426 includes Co, Cr, Pt, Si, and O as a method for reducing the noise of the medium and improving the SNR, and the magnetic crystal grain size is substantially constant in the film thickness direction. A magnetic recording layer having a granular structure having a region with more oxygen than the surface layer on the interface side with the intermediate layer is disclosed. Japanese Patent Laid-Open No. 2006-164440 discloses a granular perpendicular magnetic recording medium in which nonmagnetic grain boundaries are kept uniform in the film thickness direction, and the grain size of ferromagnetic crystal grains is made uniform and refined. Yes.

特開２００４−３１０９１０号公報には、酸化物を結晶粒界に偏析させたグラニュラー構造の記録層に酸化物を含まないＣｏ−Ｃｒ系合金層を積層した構造が開示されている。また、特開２００６−３０９９１９号公報には、磁性層を、グラニュラー構造を有する二層以上の層から形成し、下層の磁性層は上層の磁性層に比べて非磁性非固溶の原子濃度を大きくする方法が開示されている。 Japanese Patent Laid-Open No. 2004-310910 discloses a structure in which a Co—Cr alloy layer not containing an oxide is laminated on a granular recording layer in which an oxide is segregated at a grain boundary. Japanese Patent Laid-Open No. 2006-309919 discloses that a magnetic layer is formed of two or more layers having a granular structure, and the lower magnetic layer has a nonmagnetic non-solid solution atomic concentration compared to the upper magnetic layer. A method of enlarging is disclosed.

特開２００５−１９０５５２号公報JP-A-2005-190552 特開２００６−３０２４２６号公報JP 2006-302426 A 特開２００６−１６４４４０号公報JP 2006-164440 A 特開２００４−３１０９１０号公報JP 2004-310910 A 特開２００６−３０９９１９号公報JP 2006-309919 A IEEE Transactions on Magnetics, Vol.40, No.4, July 2004, pp. 2498-2500, “Role of Oxygen Incorporation in Co-Cr-Pt-Si-O Perpendicular Magnetic Recording Media”IEEE Transactions on Magnetics, Vol.40, No.4, July 2004, pp. 2498-2500, “Role of Oxygen Incorporation in Co-Cr-Pt-Si-O Perpendicular Magnetic Recording Media”

上記従来の技術は、非磁性の酸化物を結晶粒界に偏析させて磁性粒子を磁気的に孤立化させ粒径を微細化するとともに粒径分散を低減することや、グラニュラー層の膜厚方向の粒界幅の変動を抑えることにより、磁気特性及び記録再生特性を向上させるのが目的である。しかしながら、ｈｃｐ構造を有するＣｏＣｒＰｔ系合金の基板面にｃ軸が垂直配向しその配向性が高くなるにつれて、対称性が高いために結晶粒が成長する際に結晶粒同士の結合が起こりやすく、粒界が均一に形成されにくいという問題が生じてきた。 The above-mentioned conventional technology segregates nonmagnetic oxides at the grain boundaries to magnetically isolate the magnetic particles to reduce the particle size and reduce the particle size dispersion, and the film thickness direction of the granular layer. It is an object to improve magnetic characteristics and recording / reproducing characteristics by suppressing fluctuations in grain boundary width. However, as the c-axis is vertically oriented on the substrate surface of the CoCrPt-based alloy having the hcp structure and the orientation thereof is increased, the crystal grains are likely to bond with each other when the crystal grains grow due to the higher symmetry. A problem has arisen that the boundaries are difficult to form uniformly.

特開２００６−３０２４２６号公報のように、酸化物生成自由エネルギーの高いＳｉＯ₂濃度が高くＣｒ濃度の低いターゲットを用いて磁性層の初期層を形成した場合、平均的な結晶粒径は減少するが、結晶粒界が均一に広がらずに結晶粒界の幅の狭いサブグレインが多く形成されて交換結合にも分散が生じる。結果として、磁気的なクラスターサイズが結晶粒径を小さくしてもそれ以上小さくならず、更なる記録密度の向上が難しいという問題が生じてきた。また、部分的に孤立化した磁性粒子は、Ｃｒが少ないために磁気異方性が非常に大きくなり、ヘッドでの記録が十分にできないという問題も生じる。 JP As JP 2006-302426, when forming the initial layer of oxide formation free energy with high SiO ₂ concentration using the low target of high Cr concentration magnetic layer, the average grain size is reduced However, the crystal grain boundaries do not spread uniformly, and a large number of subgrains with narrow crystal grain boundaries are formed, resulting in dispersion in exchange coupling. As a result, there is a problem that the magnetic cluster size is not reduced even if the crystal grain size is reduced, and it is difficult to further improve the recording density. Further, the partially isolated magnetic particles have a very large magnetic anisotropy due to a small amount of Cr, and there is a problem that recording with a head cannot be sufficiently performed.

特開２００５−１９０５５２号公報のように、隣接粒子の重心を結んだ線の粒界部分に含まれる長さから求めた粒界幅の分散を制御したり、特開２００６−１６４４４０号公報のようにグラニュラー層の膜厚方向の粒界幅の変動を制御したりするだけでは、更なるＳ／Ｎ向上に対しては十分ではなく、本発明者らは、グラニュラー構造を有する磁性層の強磁性粒子とそれ取り囲む非磁性粒界の面積の分散に着目し、ＴＥＭにより詳細に調べた結果、ある強磁性粒子に隣接する強磁性粒子によって囲まれる領域に含まれる強磁性粒子の面積で規格化した非磁性粒界の面積（規格化非磁性粒界面積）の分散がある値より大きくなると、高Ｓ／Ｎ化のために強磁性粒子の充填率を上げていくにつれて、結晶粒間に働く交換結合の分散の影響が急激に増加し、磁化反転単位をそれ以上低減できなくなることを見出した。これは、従来の技術では、粒界の交わる部分の非磁性体の面積を制御できず、磁性層粒子の充填率を向上できないことが一因と考えられる。 As disclosed in JP-A-2005-190552, dispersion of grain boundary width obtained from the length included in the grain boundary part of the line connecting the centroids of adjacent particles is controlled, or as disclosed in JP-A-2006-164440. Further, it is not sufficient to further improve the S / N ratio simply by controlling the fluctuation of the grain boundary width in the film thickness direction of the granular layer, and the present inventors have proposed that the ferromagnetic layer of the magnetic layer having the granular structure is ferromagnetic. Focusing on the dispersion of the area of the particle and the nonmagnetic grain boundary surrounding it, as a result of detailed examination by TEM, it was normalized by the area of the ferromagnetic particle included in the region surrounded by the ferromagnetic particle adjacent to a certain ferromagnetic particle When the dispersion of the nonmagnetic grain boundary area (standardized nonmagnetic grain interface area) becomes larger than a certain value, the exchange acting between the crystal grains increases as the packing ratio of the ferromagnetic grains is increased to increase the S / N ratio. The effect of bond dispersion is drastically And pressurizing, the magnetization reversal unit found that can not be reduced further. This is probably because the conventional technique cannot control the area of the nonmagnetic material at the intersection of the grain boundaries and cannot improve the filling rate of the magnetic layer particles.

特開２００４−３１０９１０号公報や特開２００６−３０９９１９号公報のように、グラニュラー構造を持つ磁性層上に酸化物を含まない強磁性金属膜を積層しただけでは、グラニュラー磁性層の偏析を促進し交換結合を低減するに伴って十分なＯＷ（over write）特性を得るために強磁性金属層を厚くする必要が生じ、その結果、分解能が大幅に劣化するためＳＮＲの改善が頭打ちになるというトレードオフの関係があった。 As described in JP-A-2004-310910 and JP-A-2006-309919, by simply laminating a ferromagnetic metal film not containing an oxide on a magnetic layer having a granular structure, the segregation of the granular magnetic layer is promoted. A trade in that it is necessary to increase the thickness of the ferromagnetic metal layer in order to obtain sufficient OW (over write) characteristics as the exchange coupling is reduced, and as a result, the resolution is greatly deteriorated, so that the improvement of the SNR reaches a peak. There was an off relationship.

本発明者らは、強磁性金属層の成長初期段階の構造に着目し、ＴＥＭにより詳細に結晶構造を調べた結果、グラニュラー磁性層表面側の結晶粒界幅が広くなると、強磁性金属層が薄い段階ではグラニュラー層の粒界構造を反映した結晶粒界を持つようになり、連続的な構造を持つようにするには強磁性金属層の膜厚を厚くしなければならないこと、強磁性金属層が薄い段階では不連続な構造を持つため、グラニュラー磁性層の結晶粒子に均一な交換結合を導入できず、その結果、反転磁界の分散の低減や反転磁界強度の低減効果が得られないということを見出した。また、強磁性金属膜はグラニュラー膜に比べて膜中の交換結合が非常に強いために、膜厚の増加に伴って反転磁界分散は低減されるものの磁気クラスターサイズが急激に増加し、高い線記録密度での急激なノイズの増加や、あるトラックに信号を記録した際に隣接トラックにおけるビット誤り率が急激に劣化するという問題（隣接トラック消去）を新たに見出した。 The present inventors paid attention to the structure at the initial stage of growth of the ferromagnetic metal layer and examined the crystal structure in detail by TEM. As a result, when the grain boundary width on the surface side of the granular magnetic layer is widened, the ferromagnetic metal layer is At the thin stage, it has crystal grain boundaries that reflect the grain boundary structure of the granular layer, and in order to have a continuous structure, the thickness of the ferromagnetic metal layer must be increased. Since the layer has a discontinuous structure when the layer is thin, uniform exchange coupling cannot be introduced into the crystal grains of the granular magnetic layer, and as a result, the dispersion of the reversal magnetic field and the effect of reducing the reversal magnetic field strength cannot be obtained. I found out. In addition, since the ferromagnetic metal film has much stronger exchange coupling in the film than the granular film, the magnetic field cluster size increases rapidly with an increase in the film thickness, but the magnetic cluster size increases rapidly. New problems have been found (abrupt increase in noise at the recording density) and a problem that the bit error rate in the adjacent track rapidly deteriorates when a signal is recorded on a track (adjacent track erasure).

本発明はこのような検討に基づいてなされたものであり、その目的は、強磁性粒子間に働く交換結合の分散を低減し、磁気クラスターサイズの低減と強磁性粒子の充填率の向上を両立し、優れたＳ／Ｎを有する隣接トラック消去の小さな熱安定性に優れた垂直磁気記録媒体、その製造方法、及び磁気記憶装置を提供することである。 The present invention has been made on the basis of such studies, and its purpose is to reduce the dispersion of exchange coupling acting between the ferromagnetic particles, and to achieve both reduction of the magnetic cluster size and improvement of the packing rate of the ferromagnetic particles. Another object of the present invention is to provide a perpendicular magnetic recording medium having excellent S / N and excellent thermal stability for erasing adjacent tracks, a method for manufacturing the same, and a magnetic storage device.

本発明の垂直磁気記録媒体は、基板上に設けられた下地層と、ＣｏとＣｒとＰｔを主体とする柱状磁性粒子及び酸化物を含み下地層の上に形成されたグラニュラー磁性層と、グラニュラー磁性層の上に形成された酸化物を含まない強磁性金属層とを有している。また、グラニュラー磁性層の磁性粒子は、（０００１）が優先配向した六方細密構造を有する。図１に示すように、グラニュラー磁性層のある強磁性粒子に隣接する強磁性粒子の面積重心を結んだ線によって囲まれる領域に含まれる面積をA_g+b、そこに含まれる粒界の面積をA_bと定義した時、グラニュラー磁性層中の規格化粒界面積A_b／A_g+bの分散が３０％以下であることを特徴とする。これにより、交換結合の分散を低減できる。ここで、磁性粒子の面積重心を求め、重心同士を結んだ線が、他の結晶粒子を跨がないものを隣接する磁性粒子と定義する。平均及び分散は、５００ｎｍ×５００ｎｍ以上の領域に含まれる磁性粒子の観察を行って求める。 The perpendicular magnetic recording medium of the present invention includes an underlayer provided on a substrate, a granular magnetic layer formed on the underlayer containing columnar magnetic particles and oxides mainly composed of Co, Cr, and Pt, and a granular layer. And a ferromagnetic metal layer not containing an oxide formed on the magnetic layer. The magnetic particles of the granular magnetic layer have a hexagonal close-packed structure in which (0001) is preferentially oriented. As shown in FIG. 1, the area included in the region surrounded by the line connecting the gravity centers of the ferromagnetic particles adjacent to the ferromagnetic particle having the granular magnetic layer is A_g + b, and the area of the grain boundary included therein is When defined as A_b, the dispersion of the normalized grain interface area A_b / A_g + b in the granular magnetic layer is 30% or less. Thereby, dispersion of exchange coupling can be reduced. Here, the area center of gravity of the magnetic particles is obtained, and the line where the centers of gravity do not straddle other crystal particles is defined as an adjacent magnetic particle. The average and dispersion are obtained by observing magnetic particles contained in a region of 500 nm × 500 nm or more.

また、本発明の垂直磁気記録媒体は、磁性粒子の面積重心を結んだ線と粒界の交わる長さから求めた粒界幅の平均値が０．５ｎｍ以上１ｎｍであることを特徴とする。これにより、交換結合を低減できる。 The perpendicular magnetic recording medium of the present invention is characterized in that the average value of the grain boundary width obtained from the length at which the line connecting the center of gravity of the magnetic grain and the grain boundary intersect is 0.5 nm or more and 1 nm. Thereby, exchange coupling can be reduced.

また、強磁性金属層がグラニュラー磁性層の結晶粒界を跨ぐ形で連続的な構造をもつことが好ましく、これは、グラニュラー磁性層の膜厚中心付近よりも上層側で結晶粒界幅を狭くすることで実現できる。これにより、交換結合の強い強磁性金属層の膜厚を最小限に抑えることができるため、隣接トラック消去に対する耐性を向上できる。そのためには例えば、グラニュラー磁性層の結晶粒界に含まれるＣｒ酸化物が膜厚方向に濃度勾配を有するようにし、強磁性金属層側のＣｒ酸化物を構成するＣｒ元素と酸素の元素濃度の和を基板側に比べて少なくするとよい。 Further, it is preferable that the ferromagnetic metal layer has a continuous structure so as to straddle the grain boundary of the granular magnetic layer. This is because the grain boundary width is narrower on the upper layer side than the center of the film thickness of the granular magnetic layer. This can be achieved. Thereby, since the film thickness of the ferromagnetic metal layer having strong exchange coupling can be minimized, the resistance to adjacent track erasure can be improved. For this purpose, for example, the Cr oxide contained in the grain boundary of the granular magnetic layer has a concentration gradient in the film thickness direction, and the element concentrations of Cr element and oxygen constituting the Cr oxide on the ferromagnetic metal layer side are adjusted. The sum should be less than the substrate side.

本発明によれば、グラニュラー磁性層の交換結合の大きさ及び分散を低減しつつ、磁性粒子の充填率を上げることができ、また、交換結合の強い強磁性金属層の膜厚を最小限に抑えつつ、ヘッドで記録した際の反転磁界の分散を低減できる。このため、従来よりもＳ／Ｎ比が改善され、トラック密度が向上するとともに、隣接トラックの消去耐性も向上できる。その結果、高いトラック密度と線記録密度の両立が可能となり、熱安定性に優れた高密度記録が可能な垂直磁気記録媒体及びそれを用いた磁気記憶装置を提供できる。 According to the present invention, it is possible to increase the filling rate of magnetic particles while reducing the size and dispersion of the exchange coupling of the granular magnetic layer, and to minimize the film thickness of the ferromagnetic metal layer having strong exchange coupling. While suppressing, dispersion of the reversal magnetic field when recording with the head can be reduced. For this reason, the S / N ratio is improved as compared with the prior art, the track density is improved, and the erasure resistance of adjacent tracks can be improved. As a result, both high track density and linear recording density can be achieved, and a perpendicular magnetic recording medium capable of high-density recording with excellent thermal stability and a magnetic storage device using the same can be provided.

以下、図面を参照しながら本発明の実施の形態を説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

図２は、本発明による垂直磁気記録媒体の一例の断面模式図である。垂直磁気記録媒体は基板４１上に、密着層４２、軟磁性下地層４３、配向と偏析を制御する下地層４４、グラニュラー磁性層４５、強磁性金属層４６、保護層４７が順次形成され、保護層４７の上には更に潤滑層が形成されている。基板４１には、ＮｉＰメッキを施したＡｌ合金や化学強化ガラスや結晶化ガラス等を用いることができる。密着層４２は、基板との密着性を向上するためのものである。ただし、本発明の目的にとって必須ではない。密着層４２には、例えば、ＮｉＴａ合金、ＡｌＴｉ合金、ＮｉＡｌ合金、ＣｏＴｉ合金、ＡｌＴａ合金などを用いることができる。 FIG. 2 is a schematic cross-sectional view of an example of a perpendicular magnetic recording medium according to the present invention. In the perpendicular magnetic recording medium, an adhesion layer 42, a soft magnetic underlayer 43, an underlayer 44 for controlling orientation and segregation, a granular magnetic layer 45, a ferromagnetic metal layer 46, and a protective layer 47 are formed in this order on a substrate 41. A lubricating layer is further formed on the layer 47. For the substrate 41, an Al alloy plated with NiP, chemically strengthened glass, crystallized glass, or the like can be used. The adhesion layer 42 is for improving adhesion with the substrate. However, it is not essential for the purpose of the present invention. For the adhesion layer 42, for example, a NiTa alloy, an AlTi alloy, a NiAl alloy, a CoTi alloy, an AlTa alloy, or the like can be used.

軟磁性下地層４３は、磁気ヘッドからの磁束のリターンパスとして機能し、ヘッドの磁界強度や磁界勾配を制御し、記録再生特性を向上させる役割を果たす。ただし、本発明の目的にとって必須ではない。軟磁性材料としては、ＮｉＦｅ、ＮｉＦｅＣｒ、ＮｉＦｅＮｂなどの結晶性の材料や、ＦｅＴａＣ、ＦｅＴｉＣなどの微結晶性の材料、ＣｏＴａＺｒ、ＣｏＮｂＺｒ、ＦｅＣｏＴａＺｒ、ＦｅＣｏＢなどのアモルファスの材料を用いることができるが、媒体表面のラフネスを小さくできるという点で、アモルファスの材料がより好ましい。軟磁性下地層の構成として、軟磁性材料からなる層をＲｕなどの薄い金属層を介して積層（ＡＦＣ構造）し、反強磁性的に結合させることで、軟磁性下地層に起因するノイズを低減することができる。軟磁性下地層の構成としては、一層のＦｅＣｏＴａＺｒ合金などの軟磁性材料からなる軟磁性下地層の下に軟磁性下地層の磁区を固定するための磁区制御層を設けた構造や、ＡＦＣ構造の下に磁区制御層を設けた構造を用いても良い。 The soft magnetic underlayer 43 functions as a return path for magnetic flux from the magnetic head, and controls the magnetic field strength and magnetic field gradient of the head to improve the recording / reproducing characteristics. However, it is not essential for the purpose of the present invention. As the soft magnetic material, a crystalline material such as NiFe, NiFeCr, or NiFeNb, a microcrystalline material such as FeTaC or FeTiC, or an amorphous material such as CoTaZr, CoNbZr, FeCoTaZr, or FeCoB can be used. An amorphous material is more preferable in that the surface roughness can be reduced. As a configuration of the soft magnetic underlayer, a layer made of a soft magnetic material is laminated via a thin metal layer such as Ru (AFC structure) and antiferromagnetically coupled, so that noise caused by the soft magnetic underlayer is reduced. Can be reduced. The structure of the soft magnetic underlayer includes a structure in which a magnetic domain control layer for fixing the magnetic domain of the soft magnetic underlayer is provided under a soft magnetic underlayer made of a soft magnetic material such as a FeCoTaZr alloy, or an AFC structure. A structure in which a magnetic domain control layer is provided below may be used.

配向と偏析を制御する下地層４４は、記録層の結晶配向性や結晶粒径、粒界幅を制御し、記録層の結晶粒間の交換結合の低減に重要な役割を果たす。配向と偏析を制御する下地層４４の膜厚、構成、材料は、上記効果が得られる範囲で設定すればよい。例えば、面心立方格子（ｆｃｃ）構造を有する金属層上に、ＲｕもしくはＲｕ合金層を形成した構成やＴｉ合金上にｆｃｃ金属を介してＲｕ合金層を形成した構成などを用いることができる。ｆｃｃ構造を有する金属層の役割は、Ｒｕの膜面垂直方向のｃ軸配向性を高めることである。特に、ｆｃｃ金属はＴａなどの微結晶系やＮｉＴａなどのアモルファス系の材料に比べて粒径及び凹凸の制御に優れており、記録層の偏析の促進と熱安定性を大きく向上できるため好ましい。ｆｃｃ構造を有する金属としては、Ｐｄ，Ｐｔ，Ｃｕ，Ｎｉやこれらを含有する合金を用いることができる。特に、Ｎｉを主成分とする少なくともＷ，Ｃｒ，ＶもしくはＣｕを一つ以上含む合金とすると、適度な粒径と凹凸を形成でき、記録層の偏析を促進できるため好ましい。 The underlayer 44 for controlling the orientation and segregation plays an important role in reducing the exchange coupling between the crystal grains of the recording layer by controlling the crystal orientation, crystal grain size and grain boundary width of the recording layer. What is necessary is just to set the film thickness of the base layer 44 which controls orientation and segregation, a structure, and material in the range with which the said effect is acquired. For example, a configuration in which a Ru or Ru alloy layer is formed on a metal layer having a face-centered cubic lattice (fcc) structure, a configuration in which a Ru alloy layer is formed on a Ti alloy via an fcc metal, or the like can be used. The role of the metal layer having the fcc structure is to enhance the c-axis orientation in the direction perpendicular to the Ru film surface. In particular, the fcc metal is preferable because it is excellent in controlling the particle size and the unevenness as compared with a microcrystalline material such as Ta and an amorphous material such as NiTa, and can greatly enhance the segregation and thermal stability of the recording layer. As the metal having the fcc structure, Pd, Pt, Cu, Ni and alloys containing these can be used. In particular, an alloy containing at least one of W, Cr, V, or Cu containing Ni as a main component is preferable because an appropriate grain size and unevenness can be formed and segregation of the recording layer can be promoted.

ｆｃｃ金属の直下に、Ｃｒ−Ｔｉ合金、Ｃｒ−Ｔａ合金、Ｎｉ−Ｔａ合金、Ａｌ−Ｔｉ合金などのアモルファス層やＴａなどの微結晶層を設けると、ｆｃｃ層の（１１１）配向性を高め、その上に成長するＲｕ合金層及びグラニュラー磁性層の（０００１）配向性を高めることができるため好ましい。ＲｕもしくはＲｕ合金層の役割は、グラニュラー磁性層の結晶粒径及び粒界幅の分散の低減による結晶粒間の交換結合を均一に低減することある。上記効果を得るためには、例えば、ＲｕもしくはＲｕ合金層を二層以上に分けて形成し、下層側には結晶配向性を向上させる機能を、上層側にはグラニュラー磁性層の偏析を制御させる機能を持たせると良い。これにより、配向の劣化を抑えて、記録層の偏析を促進できる。 When an amorphous layer such as Cr—Ti alloy, Cr—Ta alloy, Ni—Ta alloy, Al—Ti alloy or a microcrystalline layer such as Ta is provided directly under the fcc metal, the (111) orientation of the fcc layer is increased. It is preferable because the (0001) orientation of the Ru alloy layer and the granular magnetic layer grown thereon can be improved. The role of the Ru or Ru alloy layer is to uniformly reduce exchange coupling between crystal grains by reducing dispersion of the crystal grain size and grain boundary width of the granular magnetic layer. In order to obtain the above effect, for example, the Ru or Ru alloy layer is formed by dividing it into two or more layers, the lower layer side has a function of improving crystal orientation, and the upper layer side controls segregation of the granular magnetic layer. It is good to have a function. Thereby, the deterioration of orientation can be suppressed and segregation of the recording layer can be promoted.

下層のＲｕもしくはＲｕ合金層を形成する際には、スパッタガス圧を０．５−１Ｐａ程度の低ガス圧とし、２ｎｍ／ｓ以上の高レートで形成すると配向性を高めることができる。Ｒｕ粒子の結晶粒の肥大化を防ぐため、微量の酸素をＡｒガスに添加すると効果的である。Ｒｕ合金としては、Ｒｕ−Ｔｉ、Ｒｕ−Ｂ、Ｒｕ−Ｈｆ、Ｒｕ−Ｔａなどを用いることができる。上層側のＲｕもしくはＲｕ合金層を形成する際には、例えば、５Ｐａ以上の高ガス圧、１ｎｍ／ｓ程度の低レートプロセスで形成することで、スパッタ粒子の運動エネルギーを抑えてシャドウイング効果によりＲｕもしくはＲｕ合金粒子の物理的な分離を促進することが有効である。更に、記録層側との界面部分を、ＲｕもしくはＲｕ合金粒子の周りを酸化物や窒化物が取り囲んだグラニュラー膜とすると、磁性層の偏析を更に促進することができるためより好ましい。 When forming the lower Ru or Ru alloy layer, the orientation can be improved by forming the sputtering gas pressure at a low gas pressure of about 0.5-1 Pa and forming it at a high rate of 2 nm / s or more. In order to prevent enlargement of the crystal grains of the Ru particles, it is effective to add a small amount of oxygen to the Ar gas. As the Ru alloy, Ru-Ti, Ru-B, Ru-Hf, Ru-Ta, or the like can be used. When forming the Ru or Ru alloy layer on the upper layer side, for example, by forming at a high gas pressure of 5 Pa or higher and a low rate process of about 1 nm / s, the kinetic energy of the sputtered particles is suppressed and the shadowing effect is achieved. It is effective to promote physical separation of Ru or Ru alloy particles. Further, it is more preferable that the interface portion with the recording layer side is a granular film in which an oxide or nitride surrounds the Ru or Ru alloy particles because segregation of the magnetic layer can be further promoted.

このように、十分な凹凸構造や、酸化物や窒化物を粒界に偏析させた構造を作ることにより、直上のグラニュラー磁性層の粒界をＲｕもしくはＲｕ合金層の粒界上に効率良く形成できる。ＲｕもしくはＲｕ合金粒子の周りを酸化物や窒化物が取り囲んだグラニュラー膜を形成する際には、Ｒｕを主成分としＳｉ，Ｂ，Ｔｉ，Ｔａ，Ｎｂ，Ｈｆなど酸化しやすい元素を含んだ合金を、微量の酸素や窒素添加したＡｒガスを用いて反応性スパッタにより形成したり、ＲｕにＳｉＯ₂、ＴｉＯ₂、ＨｆＯ₂、Ｔａ₂Ｏ₅、Ｎｂ₂Ｏ₅などの酸化物を含有させたターゲットを用いてグラニュラー膜を形成したりすることができる。ここで、配向の劣化や粒径分散の増加を抑制するため、粒界を構成する酸化物や窒化物の量や膜厚、バイアスを印加するなどの制御が重要である。 In this way, by forming a sufficiently uneven structure and a structure in which oxides and nitrides are segregated at the grain boundaries, the grain boundaries of the granular magnetic layer immediately above are efficiently formed on the grain boundaries of the Ru or Ru alloy layer. it can. When forming a granular film in which an oxide or nitride surrounds Ru or Ru alloy particles, an alloy containing Ru as a main component and an element that is easily oxidized such as Si, B, Ti, Ta, Nb, and Hf Was formed by reactive sputtering using a trace amount of oxygen or nitrogen-added Ar gas, or an oxide such as SiO ₂ , TiO ₂ , HfO ₂ , Ta ₂ O ₅ , or Nb ₂ O ₅ was added to Ru. A granular film can be formed using a target. Here, in order to suppress the deterioration of orientation and the increase in particle size dispersion, it is important to control the amount and thickness of oxides and nitrides constituting the grain boundaries, and the application of a bias.

グラニュラー磁性層４５は、強磁性結晶粒が非磁性粒界で囲まれたグラニュラー構造を有する。強磁性結晶粒は、ｈｃｐ構造を有したＣｏとＣｒとＰｔを主体とした合金からなり、優先配向は（０００１）とすると良い。ＣｏＣｒＰｔ系合金の媒体で加熱によりＣｒを粒界に偏析させた場合や、磁気テープに用いられるＣｏＯなどの材料に比べて高い垂直磁気異方性が得られるメリットがある。しかしながら、ｈｃｐ構造のｃ軸が基板に垂直配向している場合、対称性が高いため、結晶粒同士が結合したりして粒界幅が不均一になりやすいという問題がある。高Ｓ／Ｎ化を実現するためには、グラニュラー磁性層の磁性結晶粒子間に働く交換結合を均一に低減し、且つ、磁性結晶粒子の充填率を上げることが必要となる。 The granular magnetic layer 45 has a granular structure in which ferromagnetic crystal grains are surrounded by nonmagnetic grain boundaries. The ferromagnetic crystal grains are made of an alloy mainly composed of Co, Cr and Pt having an hcp structure, and the preferred orientation is preferably (0001). There is an advantage that high perpendicular magnetic anisotropy can be obtained when Cr is segregated at grain boundaries by heating with a CoCrPt-based alloy medium or when compared with materials such as CoO used for magnetic tape. However, when the c-axis of the hcp structure is oriented perpendicularly to the substrate, there is a problem that the grain boundary width is likely to be non-uniform because crystal grains are bonded to each other because of high symmetry. In order to achieve a high S / N ratio, it is necessary to uniformly reduce the exchange coupling between the magnetic crystal grains of the granular magnetic layer and to increase the filling rate of the magnetic crystal grains.

交換結合を均一に低減するためには、グラニュラー磁性層４５の初期層の粒界幅を均一に広げて、磁性層の強磁性結晶粒子を孤立化させる必要がある。強磁性結晶粒子を取り囲む非磁性粒界部の幅が不均一な場合、近接粒子間に働く交換結合は粒界幅の最も狭い部分で決まるため、強磁性粒子の充填率を上げようとすると粒間の交換結合が強くなってノイズが増加し、逆に、十分に交換結合を低減しようとすると強磁性粒子の充填率が下がってジッター性のノイズが増えてＳ／Ｎの劣化を招くことが解った。また、粒界が互いに交わる部分は非磁性物質が溜まって粒界の面積が広くなりやすく、この面積が増加すると強磁性結晶粒子の充填率が下がり、Ｓ／Ｎ劣化の要因となることが解った。 In order to reduce the exchange coupling uniformly, it is necessary to uniformly widen the grain boundary width of the initial layer of the granular magnetic layer 45 and to isolate the ferromagnetic crystal grains of the magnetic layer. If the width of the nonmagnetic grain boundary surrounding the ferromagnetic crystal grain is uneven, the exchange coupling acting between adjacent grains is determined by the narrowest part of the grain boundary width. The exchange coupling becomes stronger and the noise increases, and conversely, if the exchange coupling is reduced sufficiently, the filling rate of the ferromagnetic particles is lowered and the jitter noise is increased and the S / N is deteriorated. I understand. In addition, it is understood that the area where the grain boundaries intersect with each other accumulates nonmagnetic substances and the area of the grain boundaries tends to be widened. If this area increases, the filling rate of the ferromagnetic crystal grains decreases, which causes S / N degradation. It was.

発明者らの検討の結果、ある強磁性粒子に隣接する強磁性粒子の面積重心を結んだ線によって囲まれる面積をA_g+b、そこに含まれる粒界の面積をA_bと定義した時、グラニュラー磁性層中の規格化粒界面積A_b／A_g+bの分散が３０％以下であることが好ましいことが解った。これにより交換結合の分散を低減できるため、磁気クラスターサイズの増加や分散の増加を最小限に抑えて、強磁性粒子の充填率を高めることが可能となる。また、同じ結晶粒の面積であれば、粒子サイズを大きくできるため、熱安定性も向上できる。 As a result of the inventors' investigation, when the area surrounded by a line connecting the center of gravity of a ferromagnetic particle adjacent to a certain ferromagnetic particle is defined as A_g + b and the area of the grain boundary contained therein is defined as A_b, It was found that the dispersion of the normalized grain interface area A_b / A_g + b in the magnetic layer is preferably 30% or less. As a result, the dispersion of exchange coupling can be reduced, so that the increase of the magnetic cluster size and the increase of the dispersion can be minimized and the filling rate of the ferromagnetic particles can be increased. In addition, since the grain size can be increased if the area of the same crystal grains, the thermal stability can be improved.

また、磁性粒子の面積重心を結んだ線と粒界の交わる長さから求めた粒界幅の平均値が０．５ｎｍ以上１ｎｍであることが好ましい。これにより、交換結合を低減でき、大幅にＳ／Ｎを向上できる。 Moreover, it is preferable that the average value of the grain boundary width obtained from the length where the line connecting the center of gravity of the magnetic particle and the grain boundary intersect is 0.5 nm or more and 1 nm. Thereby, exchange coupling can be reduced and S / N can be improved significantly.

グラニュラー磁性層の下層の結晶粒界幅を均一に広げるために酸化物生成自由エネルギーの高いＳｉ，Ｔｉ，Ｎｂ，Ｔａなどの酸化物を増やした場合、サブグレインが多数形成されて粒界幅が均一に広がりにくく、また、粒界が交わる部分には非磁性体の溜まりができやすいことが解った。一方、酸化物生成自由エネルギーの低いＣｒは、それだけでは均一に粒界を形成しにくいが、酸化物生成自由エネルギーの高いＳｉ，Ｔｉ，Ｎｂ，Ｔａなどの酸化物などにより粒界のきっかけを作ることで、Ｃｒの酸化物が結晶粒界に優先的に析出し、均一な幅の結晶粒界が形成されることを見出した。Ｃｒ酸化物を効果的に粒界に偏析させ、且つ、粒界の交わる部分の面積の増加を抑えるためには、上述の下地層の構造に加えて、グラニュラー磁性層を形成する際のスパッタガスに含まれる酸素濃度と基板に印加するバイアス電圧が重要である。基板に負のＤＣバイアス電圧を印加し、且つ、その絶対値を２５０Ｖ以上と高くし、且つ、十分に酸素を供給してＣｒ酸化物を形成することで、酸化物の結晶粒界への偏析を促進し、粒界が交わる部分の面積の増加を抑えつつ均一な幅の非磁性粒界を形成できる。結果として、交換結合の均一な低減と強磁性結晶粒子の充填率の向上が可能となり、低ノイズ性と高分解能が実現され、高いＳ／Ｎが実現される。 When the oxide such as Si, Ti, Nb, and Ta with high free energy for oxide formation is increased in order to uniformly widen the grain boundary width of the lower layer of the granular magnetic layer, a large number of subgrains are formed and the grain boundary width is increased. It was found that it was difficult to spread uniformly, and that nonmagnetic materials could easily accumulate at the intersections of grain boundaries. On the other hand, Cr with low oxide formation free energy is difficult to form a uniform grain boundary by itself, but causes a grain boundary with oxides such as Si, Ti, Nb, and Ta having high oxide generation free energy. As a result, it has been found that the Cr oxide is preferentially precipitated at the crystal grain boundaries, and a crystal grain boundary having a uniform width is formed. In order to effectively segregate Cr oxides at the grain boundaries and suppress an increase in the area of the intersections of the grain boundaries, in addition to the structure of the above-mentioned underlayer, a sputtering gas for forming the granular magnetic layer The oxygen concentration contained in the substrate and the bias voltage applied to the substrate are important. A negative DC bias voltage is applied to the substrate, its absolute value is increased to 250 V or more, and sufficient oxygen is supplied to form Cr oxide, thereby segregating the oxide to the crystal grain boundaries. And a non-magnetic grain boundary having a uniform width can be formed while suppressing an increase in the area where the grain boundary intersects. As a result, the exchange coupling can be reduced uniformly and the filling rate of the ferromagnetic crystal particles can be improved, low noise and high resolution can be realized, and high S / N can be realized.

ただし、印加バイアス電圧が高くなると、グラニュラー磁性層の結晶粒が下地層の結晶粒子の構造を跨いで成長し肥大化しやすくなるため、下地層表面に十分な凹凸構造や、酸化物や窒化物を粒界に偏析させた構造をつくることで、直上のグラニュラー磁性層の粒界位置を固定する必要がある。また、印加バイアス電圧が高くなると、酸化物からの酸素欠損が生じるため、スパッタガス中の酸素濃度を高く設定することが重要である。更に、基板に印加するバイアス電圧をパルス状にすることで、基板表面の酸化物や窒化物のチャージアップを防ぎ酸化物や窒化物の運動エネルギーを高めることで、酸化物や窒化物の粒界への偏析を促進できる。また、酸素や窒素を効率的に取り込むことで酸素、窒素欠損を抑えて、強磁性粒子からの分離を促進できる。 However, when the applied bias voltage increases, the crystal grains of the granular magnetic layer grow and straddle over the structure of the crystal grains of the underlayer, so that a sufficient uneven structure, oxide or nitride is formed on the surface of the underlayer. It is necessary to fix the grain boundary position of the granular magnetic layer directly above by creating a structure segregated at the grain boundary. Further, when the applied bias voltage is increased, oxygen vacancies are generated from the oxide. Therefore, it is important to set the oxygen concentration in the sputtering gas high. In addition, the bias voltage applied to the substrate is pulsed to prevent oxide and nitride charge-up on the substrate surface and increase the kinetic energy of the oxide and nitride. Can promote segregation. In addition, oxygen and nitrogen deficiency can be suppressed by efficiently taking in oxygen and nitrogen, and separation from ferromagnetic particles can be promoted.

一方、磁気クラスターサイズの分散及び反転磁界の分散を低減するためには、強磁性金属層を介して磁性層の結晶粒子間に均一な交換結合を導入することが有効である。本発明者らは、強磁性金属層の粒子が成長初期段階からグラニュラー磁性層の粒界を跨いで成長し、実質的に連続的な構造を持つことで、磁気クラスターサイズの増加を最小限に抑えつつ磁性層の結晶粒子間に均一な交換結合を導入できることを見出した。強磁性金属層を上記構造とするためには、グラニュラー磁性層の上層側の粒界幅を均一に狭めることが重要であり、グラニュラー磁性層の下層側から中央付近の粒界幅に比べて表面側２ｎｍの領域の粒界幅を０．３ｎｍ以上狭くすることが好ましい。このような構造を実現するためには、酸化物を含む磁性層の上層の酸化物を酸化物生成自由エネルギーの高いＳｉ，Ｔｉ，Ｎｂ，Ｔａなどの酸化物とし、且つ、Ｃｒ酸化物を下層より少なくすることが重要である。粒界幅を広げる作用を有するＣｒ酸化物を磁性層の上層側で少なくすることで粒界幅が狭まるが、Ｓｉ，Ｔｉ，Ｎｂ，Ｔａなどの酸化物が存在することにより下層の結晶粒界を反映する形で徐々に均一に粒界幅が狭まり、強磁性金属層の結晶粒子がこの結晶粒界を跨ぐような形で成長しやすくできる。この時、酸化物を含む磁性層の上層側には、粒界幅の均一な減少に伴って、強磁性金属層に比べれば弱いが均一な交換結合が働くことで、反転磁界分散及びその平均的な磁界強度の低減にも寄与する。グラニュラー磁性層の上層側は、下層側に比べて酸素を減らして形成すると、Ｃｒ酸化物の形成を抑制できる。酸素を導入せずに形成すると更にＣｒ酸化物の形成が抑制されるためより好ましい。グラニュラー層上層側を形成する際には、下層側に比べて基板側に印加するバイアス電圧の大きさを小さく設定することが、交換結合を適切な大きさに抑えるのに有効である。 On the other hand, in order to reduce the dispersion of the magnetic cluster size and the dispersion of the switching magnetic field, it is effective to introduce uniform exchange coupling between the crystal grains of the magnetic layer through the ferromagnetic metal layer. The inventors of the present invention minimize the increase in the size of the magnetic cluster by having the ferromagnetic metal layer grains grow from the initial growth stage across the grain boundary of the granular magnetic layer and have a substantially continuous structure. It was found that uniform exchange coupling can be introduced between the crystal grains of the magnetic layer while suppressing it. In order to make the ferromagnetic metal layer have the above structure, it is important to uniformly narrow the grain boundary width on the upper layer side of the granular magnetic layer, and the surface is smaller than the grain boundary width near the center from the lower layer side of the granular magnetic layer. It is preferable to narrow the grain boundary width in the region of 2 nm on the side by 0.3 nm or more. In order to realize such a structure, the oxide in the upper layer of the magnetic layer containing the oxide is an oxide such as Si, Ti, Nb, Ta having a high free energy for generating an oxide, and the Cr oxide is used in the lower layer. It is important to make less. The grain boundary width is reduced by reducing the Cr oxide having the effect of widening the grain boundary width on the upper layer side of the magnetic layer. However, the presence of oxides such as Si, Ti, Nb, Ta causes the lower grain boundary. The grain boundary width is gradually and uniformly narrowed in a manner reflecting the above, and the crystal grains of the ferromagnetic metal layer can easily grow in such a form as to straddle the crystal grain boundary. At this time, on the upper layer side of the magnetic layer containing the oxide, with uniform reduction of the grain boundary width, a weak but uniform exchange coupling works as compared with the ferromagnetic metal layer. This contributes to a reduction in the magnetic field strength. If the upper layer side of the granular magnetic layer is formed by reducing oxygen compared to the lower layer side, formation of Cr oxide can be suppressed. The formation without introducing oxygen is more preferable because the formation of Cr oxide is further suppressed. When forming the upper layer side of the granular layer, setting the magnitude of the bias voltage applied to the substrate side smaller than that on the lower layer side is effective in suppressing the exchange coupling to an appropriate level.

強磁性金属層の結晶粒子がグラニュラー磁性層の結晶粒界を跨ぐような形で成長することで、グラニュラー磁性層粒子間に均一な交換結合を導入でき、クラスターサイズの分散や反転磁界分散を低減できる。このような構成とすることで、強磁性金属層の膜厚を最小限に抑えることができるため、分解能が向上し、磁気クラスターサイズの増加も最小限に抑えられるため、高い線記録密度でのノイズの増加、隣接トラック消去を抑えることができることを新たに見出した。 Ferromagnetic metal layer crystal grains grow across the grain boundaries of the granular magnetic layer, allowing uniform exchange coupling between the granular magnetic layer grains, reducing cluster size dispersion and switching field dispersion. it can. With such a configuration, the film thickness of the ferromagnetic metal layer can be minimized, so that the resolution is improved and the increase in the magnetic cluster size is also minimized. It was newly found that noise increase and adjacent track erasure can be suppressed.

低ノイズ性を実現するため、グラニュラー磁性層としては、Ｃｏを主成分とし、少なくともＣｒとＰｔを含み酸化物を含む、Ｃｏ−Ｃｒ−Ｐｔ−Ｂ合金、Ｃｏ−Ｃｒ−Ｐｔ−Ｍｏ合金、Ｃｏ−Ｃｒ−Ｐｔ−Ｎｂ合金、Ｃｏ−Ｃｒ−Ｐｔ−Ｔａ合金と、Ｓｉ酸化物、Ｔａ酸化物、Ｎｂ酸化物、Ｔｉ酸化物を少なくとも一種類含み、Ｃｒ酸化物の濃度が下層側で高く強磁性金属層との界面側で少ないグラニュラー膜とすると良い。上記構造のグラニュラー磁性層を形成する際には、スパッタ中の酸素濃度やバイアス電圧、ガス圧に勾配を持たせることにより構造を制御しても良いし、異なるターゲットを用いて複数の層から形成しても良い。 In order to realize low noise properties, the granular magnetic layer is composed mainly of Co, and includes Co—Cr—Pt—B alloy, Co—Cr—Pt—Mo alloy, Co containing at least Cr and Pt and containing oxide. -Cr-Pt-Nb alloy, Co-Cr-Pt-Ta alloy and at least one kind of Si oxide, Ta oxide, Nb oxide, Ti oxide, and the concentration of Cr oxide is high on the lower layer side and strong It is preferable to use a small granular film on the interface side with the magnetic metal layer. When the granular magnetic layer having the above structure is formed, the structure may be controlled by giving a gradient to the oxygen concentration, bias voltage, and gas pressure during sputtering, or formed from a plurality of layers using different targets. You may do it.

強磁性金属層を構成する材料としては、Ｃｏ／ＰｔやＣｏ／Ｐｄなどの人工格子や、Ｃｏを主成とし少なくともＣｒを含有する合金などを用いることができる。特に、Ｃｏを主成分とし少なくともＣｒを含有する合金、すなわちＣｏ−Ｃｒ合金、Ｃｏ−Ｃｒ−Ｂ合金、Ｃｏ−Ｃｒ−Ｍｏ合金、Ｃｏ−Ｃｒ−Ｎｂ合金、Ｃｏ−Ｃｒ−Ｔａ合金、Ｃｏ−Ｃｒ−Ｐｔ−Ｃｕ合金、Ｃｏ−Ｃｒ−Ｐｔ−Ｂ合金、Ｃｏ−Ｃｒ−Ｐｔ−Ｍｏ合金、Ｃｏ−Ｃｒ−Ｐｔ−Ｎｂ合金、Ｃｏ−Ｃｒ−Ｐｔ−Ｔａ合金、Ｃｏ−Ｃｒ−Ｐｔ−Ｍｏ−Ｂ合金、Ｃｏ−Ｃｒ−Ｐｔ−Ｎｂ−Ｂ合金、Ｃｏ−Ｃｒ−Ｐｔ−Ｔａ−Ｂ合金、Ｃｏ−Ｃｒ−Ｐｔ−Ｃｕ−Ｂ合金などを用いると、ノイズ増加を最小限に抑えて反転磁界分散を低減でき、耐食性も向上できるため好ましい。また、強磁性金属層の膜厚は、平均的な反転磁界強度、反転磁界の分散を低減でき、且つ、熱安定性が満足される範囲内で、できるだけ薄くすることが好ましい。これにより、隣接トラック消去を抑えることができる。強磁性金属層の膜厚は、好ましくは１ｎｍから５ｎｍ程度である。 As a material constituting the ferromagnetic metal layer, an artificial lattice such as Co / Pt or Co / Pd, or an alloy mainly containing Co and containing at least Cr can be used. In particular, an alloy containing Co as a main component and containing at least Cr, that is, a Co—Cr alloy, a Co—Cr—B alloy, a Co—Cr—Mo alloy, a Co—Cr—Nb alloy, a Co—Cr—Ta alloy, Co— Cr-Pt-Cu alloy, Co-Cr-Pt-B alloy, Co-Cr-Pt-Mo alloy, Co-Cr-Pt-Nb alloy, Co-Cr-Pt-Ta alloy, Co-Cr-Pt-Mo -B alloy, Co-Cr-Pt-Nb-B alloy, Co-Cr-Pt-Ta-B alloy, Co-Cr-Pt-Cu-B alloy, etc. It is preferable because magnetic field dispersion can be reduced and corrosion resistance can be improved. The film thickness of the ferromagnetic metal layer is preferably as thin as possible as long as the average reversal magnetic field strength and dispersion of the reversal magnetic field can be reduced and the thermal stability is satisfied. Thereby, adjacent track erasure can be suppressed. The film thickness of the ferromagnetic metal layer is preferably about 1 nm to 5 nm.

強磁性金属層と酸化物を含む磁性層の間に、両者の間の交換結合を制御する層を挿入しても良い。上下層の交換結合を制御する層としては、Ｒｕ，ＣｏＲｕ，ＣｏＣｒ−ＳｉＯ₂などを用いることができる。 A layer for controlling exchange coupling between the ferromagnetic metal layer and the oxide-containing magnetic layer may be inserted. As the layer for controlling the exchange coupling between the upper and lower layers, Ru, CoRu, CoCr—SiO ₂ or the like can be used.

［実施例１］
本実施例の垂直磁気記録媒体は、アネルバ株式会社製のスパッタリング装置（Ｃ−３０１０）を用いて作製した。このスパッタリング装置は１０個のプロセスチャンバと１個の基板導入チャンバからなり、各チャンバは独立に排気されている。すべてのプロセスチャンバを１×１０^-5Ｐａ以下の真空度まで排気した後、基板を乗せたキャリアを各プロセスチャンバに移動させることにより、順にプロセスを実施した。スパッタ用のプロセスチャンバには磁石回転型のマグネトロンスパッタカソードを設置し、金属膜及びカーボン膜はＤＣスパッタにより形成した。 [Example 1]
The perpendicular magnetic recording medium of this example was manufactured using a sputtering apparatus (C-3010) manufactured by Anerva Corporation. This sputtering apparatus includes 10 process chambers and one substrate introduction chamber, and each chamber is evacuated independently. After evacuating all the process chambers to a vacuum of 1 × 10 ⁻⁵ Pa or less, the process was performed in order by moving the carrier on which the substrate was placed to each process chamber. A magnet rotating type magnetron sputtering cathode was installed in the sputtering process chamber, and the metal film and the carbon film were formed by DC sputtering.

基板４１には直径６３．５ｍｍのガラス基板を用いた。基板４１上に、基板との密着性を高めるためにＮｉ−４０at.%Ｔａ合金からなる膜厚３０ｎｍの密着層４２を形成した。スパッタガスとしてアルゴンガスを用い、総ガス圧０．７Ｐａとした。その上の軟磁性下地層４３は、ＦｅＣｏＴａＺｒ合金を薄いＲｕを介して積層した三層構造とした。ここでＦｅＣｏＴａＺｒ合金としては、５１at.%Ｆｅ−３４at.%Ｃｏ−１０at.%Ｔａ−５at.%Ｚｒを用い、一層あたりの膜厚を１０ｎｍとした。この時のＲｕの膜厚は０．４ｎｍとした。ＦｅＣｏＴａＺｒ層、Ｒｕ層形成の際には、スパッタガスとしてアルゴンガスを用い、総ガス圧０．７Ｐａとした。 As the substrate 41, a glass substrate having a diameter of 63.5 mm was used. On the substrate 41, an adhesion layer 42 having a film thickness of 30 nm made of a Ni-40 at.% Ta alloy was formed in order to improve adhesion with the substrate. Argon gas was used as the sputtering gas, and the total gas pressure was 0.7 Pa. The soft magnetic underlayer 43 thereon has a three-layer structure in which an FeCoTaZr alloy is laminated via thin Ru. Here, as the FeCoTaZr alloy, 51 at.% Fe-34 at.% Co-10 at.% Ta-5 at.% Zr was used, and the film thickness per layer was 10 nm. The film thickness of Ru at this time was 0.4 nm. In forming the FeCoTaZr layer and the Ru layer, argon gas was used as the sputtering gas, and the total gas pressure was 0.7 Pa.

配向と偏析を制御する下地層４４は、Ｎｉ−４０at.%Ｔａ層を４ｎｍ、Ｎｉ−１０at.%Ｃｒ−６at.%Ｗ層を７ｎｍ、Ｒｕを１６ｎｍ、順次形成した構成とした。ＮｉＴａ層、ＮｉＣｒＷ層形成の際には、スパッタガスとしてアルゴンガスを用い、総ガス圧０．７Ｐａとした。Ｒｕ層は二層に分けて形成した。下層８ｎｍは製膜レート２ｎｍ／ｓで形成し、スパッタガスにはアルゴンと酸素の混合ガスを用い、総ガス圧０．７Ｐａ、酸素濃度１％とした。上層８ｎｍは製膜レート１ｎｍ／ｓで形成し、スパッタガスにはアルゴガスを用い、総ガス圧を５Ｐａとした。ＲｕとＴｉ酸化物からなる層を形成する際には、Ｒｕ−１０％Ｔｉ合金ターゲットを用い、総ガス圧を６．５Ｐａ、酸素濃度を０．２％とした。 The underlayer 44 for controlling the orientation and segregation was formed by sequentially forming a Ni-40 at.% Ta layer of 4 nm, a Ni-10 at.% Cr-6 at.% W layer of 7 nm, and a Ru of 16 nm. In forming the NiTa layer and the NiCrW layer, argon gas was used as the sputtering gas, and the total gas pressure was 0.7 Pa. The Ru layer was formed in two layers. The lower layer 8 nm was formed at a film forming rate of 2 nm / s, a mixed gas of argon and oxygen was used as the sputtering gas, the total gas pressure was 0.7 Pa, and the oxygen concentration was 1%. The upper layer 8 nm was formed at a film forming rate of 1 nm / s, Argo gas was used as the sputtering gas, and the total gas pressure was 5 Pa. When forming a layer made of Ru and Ti oxide, a Ru-10% Ti alloy target was used, the total gas pressure was 6.5 Pa, and the oxygen concentration was 0.2%.

グラニュラー磁性層４５は、［６１at.%Ｃｏ−２１at.%Ｃｒ−１８at.%Ｐｔ］とＳｉＯ₂を９４ｍｏｌ：６ｍｏｌの割合で含有する複合型ターゲットを用い、３ｎｍ／ｓの製膜レートで形成した。膜厚は１２．９ｎｍとした。グラニュラー磁性層４５を形成する際には、始めに０．３秒間、総ガス圧６．５Ｐａ、酸素濃度２．５％の条件でアルゴンと酸素の混合ガスを流した後、製膜開始から２．４秒間は総ガス圧を５Ｐａ、酸素濃度を３％とし、基板バイアスを−２７５Ｖの条件で形成し、製膜終了までの１．９秒間は総ガス圧を３．５Ｐａ、酸素濃度を０％とし、基板バイアスを−２００Ｖの条件で形成した。 The granular magnetic layer 45 was formed at a film forming rate of 3 nm / s using a composite target containing [61 at.% Co-21 at.% Cr-18 at.% Pt] and SiO ₂ at a ratio of 94 mol: 6 mol. . The film thickness was 12.9 nm. When forming the granular magnetic layer 45, first, after flowing a mixed gas of argon and oxygen for 0.3 seconds under conditions of a total gas pressure of 6.5 Pa and an oxygen concentration of 2.5%, the film formation is started 2 For 4 seconds, the total gas pressure is 5 Pa, the oxygen concentration is 3%, the substrate bias is -275 V, and the total gas pressure is 3.5 Pa and the oxygen concentration is 0 for 1.9 seconds until film formation is completed. %, And the substrate bias was -200V.

酸化物を含まない強磁性金属層４６を形成する際には、Ｃｏ−１５at.%Ｃｒ−１４at.%Ｐｔ−８at.%Ｂ合金ターゲットを用い、スパッタガスとしてＡｒを用い、総ガス圧を０．６Ｐａとした。膜厚は４．５ｎｍとした。 When forming the ferromagnetic metal layer 46 containing no oxide, a Co-15 at.% Cr-14 at.% Pt-8 at.% B alloy target is used, Ar is used as the sputtering gas, and the total gas pressure is 0. .6 Pa. The film thickness was 4.5 nm.

続いて、保護層４７として厚さ３．５ｎｍのダイアモンドライクカーボン膜を形成した。その表面に有機系の潤滑剤を塗布して潤滑層を形成した。 Subsequently, a diamond-like carbon film having a thickness of 3.5 nm was formed as the protective layer 47. An organic lubricant was applied to the surface to form a lubricating layer.

［実施例２］
配向と偏析を制御する下地層４４は、Ｃｒ−５０at.%Ｔｉ層を２ｎｍ、Ｎｉ−８at.%Ｗ層を４ｎｍ、Ｒｕを１９ｎｍ、ＲｕとＢ酸化物からなる層を０．８ｎｍ、順次形成した構成とした。ＮｉＴａ層、ＮｉＷ層形成の際には、スパッタガスとしてアルゴンガスを用い、総ガス圧０．７Ｐａとした。Ｒｕ層は二層に分けて形成した。下層８ｎｍは製膜レート２ｎｍ／ｓで形成し、スパッタガスにはアルゴンと酸素の混合ガスを用い、総ガス圧０．７Ｐａ、酸素濃度１％とした。上層１１ｎｍは製膜レート１ｎｍ／ｓで形成し、スパッタガスにはアルゴガスを用い、総ガス圧を５Ｐａとした。ＲｕとＢ酸化物からなる層を形成する際には、Ｒｕ−５％Ｂ合金ターゲットを用い、総ガス圧を６．５Ｐａ、酸素濃度を０．２％とした。 [Example 2]
The underlayer 44 for controlling the orientation and segregation is formed by sequentially forming a Cr-50 at.% Ti layer of 2 nm, a Ni-8 at.% W layer of 4 nm, a Ru of 19 nm, and a Ru and B oxide layer of 0.8 nm. The configuration was as follows. In forming the NiTa layer and the NiW layer, argon gas was used as the sputtering gas, and the total gas pressure was 0.7 Pa. The Ru layer was formed in two layers. The lower layer 8 nm was formed at a film forming rate of 2 nm / s, a mixed gas of argon and oxygen was used as the sputtering gas, the total gas pressure was 0.7 Pa, and the oxygen concentration was 1%. The upper layer 11 nm was formed at a film forming rate of 1 nm / s, the argon gas was used as the sputtering gas, and the total gas pressure was 5 Pa. When forming a layer made of Ru and B oxide, a Ru-5% B alloy target was used, the total gas pressure was 6.5 Pa, and the oxygen concentration was 0.2%.

グラニュラー磁性層４５は、［６５at.%Ｃｏ−１７at.%Ｃｒ−１８at.%Ｐｔ］とＳｉＯ₂を９２ｍｏｌ：８ｍｏｌの割合で含有する複合型ターゲットを用い、３ｎｍ／ｓの製膜レートで、基板バイアスを−２７５Ｖとした条件で膜厚９．９ｎｍ形成後、続けて［５９at.%Ｃｏ−２３at.%Ｃｒ−１８at.%Ｐｔ］とＳｉＯ₂を９５ｍｏｌ：５ｍｏｌの割合で含有する複合型ターゲットを用い、３ｎｍ／ｓの製膜レートで基板バイアス−が１５０Ｖの条件で膜厚３ｎｍ形成した。 The granular magnetic layer 45 uses a composite target containing [65 at.% Co-17 at.% Cr-18 at.% Pt] and SiO ₂ at a ratio of 92 mol: 8 mol, and has a film formation rate of 3 nm / s. A composite target containing [59 at.% Co-23 at.% Cr-18 at.% Pt] and SiO ₂ at a ratio of 95 mol: 5 mol was formed after forming a film thickness of 9.9 nm under the condition that the bias was −275 V. A film thickness of 3 nm was formed at a film formation rate of 3 nm / s and a substrate bias of 150 V.

グラニュラー磁性層４５の前半９．９ｎｍを形成する際には、始めに０．３秒間、総ガス圧６．５Ｐａ、酸素濃度２．５％の条件でアルゴンと酸素の混合ガスを流した後、製膜開始から２．８秒間は総ガス圧を５Ｐａ、酸素濃度を２．３％とし、残りの０．５秒間は総ガス圧を３．５Ｐａ、酸素濃度を０％とした。グラニュラー磁性層４５の後半３ｎｍを形成する際には、Ａｒガスのみを用い、総ガス圧を３．５Ｐａとし、基板バイアス−１５０Ｖの条件で形成した。 When forming the first 9.9 nm of the granular magnetic layer 45, first, after flowing a mixed gas of argon and oxygen under the conditions of a total gas pressure of 6.5 Pa and an oxygen concentration of 2.5% for 0.3 seconds, The total gas pressure was 5 Pa and the oxygen concentration was 2.3% for 2.8 seconds from the start of film formation, and the total gas pressure was 3.5 Pa and the oxygen concentration was 0% for the remaining 0.5 seconds. When forming the latter 3 nm of the granular magnetic layer 45, only Ar gas was used, the total gas pressure was 3.5 Pa, and the substrate bias was -150V.

配向と偏析を制御する下地層４４とグラニュラー磁性層４５以外は、実施例１と同一条件とした。 Except for the underlayer 44 and the granular magnetic layer 45 for controlling the orientation and segregation, the same conditions as in Example 1 were used.

［実施例３］
配向と偏析を制御する下地層４４は、Ｃｒ−５０at.%Ｔａ層を２ｎｍ、Ｎｉ−８at.%Ｗ層を４ｎｍ、Ｒｕを１９ｎｍ、ＲｕとＴａ酸化物からなる層を０．８ｎｍ、順次形成した構成とした。ＣｒＴｉ層、ＮｉＷ層形成の際には、スパッタガスとしてアルゴンガスを用い、総ガス圧０．７Ｐａとした。Ｒｕ層は二層に分けて形成した。下層８ｎｍは製膜レート２ｎｍ／ｓで形成し、スパッタガスにはアルゴンと酸素の混合ガスを用い、総ガス圧０．７Ｐａ、酸素濃度１％とした。上層１１ｎｍは製膜レート１ｎｍ／ｓで形成し、スパッタガスにはアルゴガスを用い、総ガス圧を５Ｐａとした。ＲｕとＴａ酸化物からなる層を形成する際には、Ｒｕ−１０％Ｔａ合金ターゲットを用い、総ガス圧を６．５Ｐａ、酸素濃度を０．２％とした。 [Example 3]
The underlayer 44 for controlling orientation and segregation is formed by sequentially forming a Cr-50 at.% Ta layer of 2 nm, a Ni-8 at.% W layer of 4 nm, a Ru of 19 nm, and a Ru and Ta oxide layer of 0.8 nm. The configuration was as follows. In forming the CrTi layer and the NiW layer, argon gas was used as the sputtering gas, and the total gas pressure was 0.7 Pa. The Ru layer was formed in two layers. The lower layer 8 nm was formed at a film forming rate of 2 nm / s, a mixed gas of argon and oxygen was used as the sputtering gas, the total gas pressure was 0.7 Pa, and the oxygen concentration was 1%. The upper layer 11 nm was formed at a film forming rate of 1 nm / s, the argon gas was used as the sputtering gas, and the total gas pressure was 5 Pa. When forming a layer made of Ru and Ta oxide, a Ru-10% Ta alloy target was used, the total gas pressure was 6.5 Pa, and the oxygen concentration was 0.2%.

グラニュラー磁性層４５は、［６３at.%Ｃｏ−１９at.%Ｃｒ−１８at.%Ｐｔ］とＴａ₂Ｏ₅を９８ｍｏｌ：２ｍｏｌの割合で含有する複合型ターゲットを用い、３ｎｍ／ｓの製膜レートで基板バイアスを−２７５Ｖとした条件で膜厚９．９ｎｍ形成後、続けて［５９at.%Ｃｏ−２３at.%Ｃｒ−１８at.%Ｐｔ］とＳｉＯ₂を９５ｍｏｌ：５ｍｏｌの割合で含有する複合型ターゲットを用い、３ｎｍ／ｓの製膜レートで基板バイアスを−２７５Ｖとした条件で膜厚３ｎｍ形成した。グラニュラー磁性層４５の前半９．９ｎｍを形成する際には、始めに０．３秒間、総ガス圧６．５Ｐａ、酸素濃度２．５％の条件でアルゴンと酸素の混合ガスを流した後、製膜開始から２．８秒間は総ガス圧を５Ｐａ、酸素濃度を２．３％とし、残りの０．５秒間は総ガス圧を３．５Ｐａ、酸素濃度を０％とした。グラニュラー磁性層４５の後半３ｎｍを形成する際には、Ａｒガスのみを用い、総ガス圧を３．５Ｐａとした。 The granular magnetic layer 45 uses a composite target containing [63 at.% Co-19 at.% Cr-18 at.% Pt] and Ta ₂ O ₅ in a ratio of 98 mol: 2 mol, and has a film formation rate of 3 nm / s. A composite target containing [59 at.% Co-23 at.% Cr-18 at.% Pt] and SiO ₂ at a ratio of 95 mol: 5 mol after forming a film thickness of 9.9 nm under the condition that the substrate bias is −275 V. The film thickness was 3 nm under the condition that the substrate bias was −275 V at a film formation rate of 3 nm / s. When forming the first 9.9 nm of the granular magnetic layer 45, first, after flowing a mixed gas of argon and oxygen under the conditions of a total gas pressure of 6.5 Pa and an oxygen concentration of 2.5% for 0.3 seconds, The total gas pressure was 5 Pa and the oxygen concentration was 2.3% for 2.8 seconds from the start of film formation, and the total gas pressure was 3.5 Pa and the oxygen concentration was 0% for the remaining 0.5 seconds. When forming the latter half 3 nm of the granular magnetic layer 45, only Ar gas was used and the total gas pressure was 3.5 Pa.

酸化物を含まない強磁性金属層４６には、Ｃｏ−２２at.%Ｃｒ−１４at.%Ｐｔ合金ターゲットを用い、スパッタガスとしてＡｒを用い、総ガス圧を０．６Ｐａとした。膜厚は４ｎｍとした。 For the ferromagnetic metal layer 46 not containing oxide, a Co-22 at.% Cr-14 at.% Pt alloy target was used, Ar was used as the sputtering gas, and the total gas pressure was 0.6 Pa. The film thickness was 4 nm.

配向と偏析を制御する下地層４４、グラニュラー磁性層４５、及び強磁性金属層４６以外は、実施例１と同一条件とした。 Except for the underlayer 44, the granular magnetic layer 45, and the ferromagnetic metal layer 46 for controlling the orientation and segregation, the same conditions as in Example 1 were used.

［実施例４］
グラニュラー磁性層４５の前半９．９ｎｍで、［６３at.%Ｃｏ−１９at.%Ｃｒ−１８at.%Ｐｔ］とＮｂ₂Ｏ₅を９８ｍｏｌ：２ｍｏｌの割合で含有する複合型ターゲットを用いたこと以外、実施例３と同一条件とした。 [Example 4]
Other than using a composite target containing [63 at.% Co-19 at.% Cr-18 at.% Pt] and Nb ₂ O ₅ at a ratio of 98 mol: 2 mol in the first 9.9 nm of the granular magnetic layer 45, The conditions were the same as in Example 3.

［実施例５］
グラニュラー磁性層４５の前半９．９ｎｍで、［６３at.%Ｃｏ−１９at.%Ｃｒ−１８at.%Ｐｔ］とＴｉＯ₂を９４ｍｏｌ：６ｍｏｌの割合で含有する複合型ターゲットを用いたこと以外、実施例３と同一条件とした。 [Example 5]
Example 1 except that a composite target containing [63 at.% Co-19 at.% Cr-18 at.% Pt] and TiO ₂ at a ratio of 94 mol: 6 mol in the first 9.9 nm of the granular magnetic layer 45 was used. 3 and the same conditions.

［実施例６］
配向と偏析を制御する下地層４４は、Ｔａ層を２ｎｍ、ＴｉＴａ層を４ｎｍ、ＣｕＴｉ層を１ｎｍ、ＮｉＣｕＷ層を９ｎｍ、Ｒｕを９ｎｍ、ＲｕとＨｆ酸化物からなる層を１ｎｍ、順次形成した構成とした。ＴｉＴａ層形成の際には、Ｔｉ−３at.%Ｔａ合金ターゲットを用い、ＣｕＴｉ層形成の際には、Ｃｕ−１０at.%Ｔｉ合金ターゲットを用い、ＮｉＣｕＷ層形成の際にはＮｉ−２０at.%Ｃｕ−６at.%Ｗ合金ターゲットを用いた。Ｔａ層、ＴｉＴａ層、ＣｕＴｉ層、ＮｉＣｕＷ層形成の際には、スパッタガスとしてアルゴンガスを用い、総ガス圧０．７Ｐａとした。ＣｕＴｉ層を形成する前に、ＴｉＴａ層の表面を総ガス圧０．７Ｐａ（酸素濃度１％）のアルゴンと酸素雰囲気中に３秒間暴露し、表面の一部を酸化させた。Ｒｕ層は二層に分けて形成した。下層４ｎｍは製膜レート２ｎｍ／ｓで形成し、スパッタガスにはアルゴンと酸素の混合ガスを用い、総ガス圧０．７Ｐａ、酸素濃度１％とした。上層１０ｎｍは製膜レート１ｎｍ／ｓで形成し、スパッタガスにはアルゴガスを用い、総ガス圧を５Ｐａとした。ＲｕとＨｆ酸化物からなる層を形成する際には、Ｒｕ−６％Ｈｆ合金ターゲットを用い、総ガス圧を６．５Ｐａ、酸素濃度を０．２％とした。 [Example 6]
The underlayer 44 for controlling orientation and segregation is formed by sequentially forming a Ta layer of 2 nm, a TiTa layer of 4 nm, a CuTi layer of 1 nm, a NiCuW layer of 9 nm, a Ru of 9 nm, and a Ru and Hf oxide layer of 1 nm. It was. When forming a TiTa layer, a Ti-3 at.% Ta alloy target is used. When forming a CuTi layer, a Cu-10 at.% Ti alloy target is used. When forming a NiCuW layer, Ni-20 at.% Is used. A Cu-6 at.% W alloy target was used. In forming the Ta layer, TiTa layer, CuTi layer, and NiCuW layer, argon gas was used as the sputtering gas, and the total gas pressure was 0.7 Pa. Before forming the CuTi layer, the surface of the TiTa layer was exposed for 3 seconds in an argon atmosphere with a total gas pressure of 0.7 Pa (oxygen concentration 1%) to oxidize a part of the surface. The Ru layer was formed in two layers. The lower layer 4 nm was formed at a film formation rate of 2 nm / s, a mixed gas of argon and oxygen was used as the sputtering gas, the total gas pressure was 0.7 Pa, and the oxygen concentration was 1%. The upper layer 10 nm was formed at a film formation rate of 1 nm / s, the argon gas was used as the sputtering gas, and the total gas pressure was 5 Pa. When forming a layer made of Ru and Hf oxide, a Ru-6% Hf alloy target was used, the total gas pressure was 6.5 Pa, and the oxygen concentration was 0.2%.

配向と偏析を制御する下地層４４以外は実施例１と同一条件とした。 The conditions were the same as in Example 1 except for the underlayer 44 for controlling the orientation and segregation.

［実施例７］
配向と偏析を制御する下地層４４は、Ｎｉ−１０at.%Ｃｒ層を９ｎｍ、Ｒｕを１８ｎｍ順次形成した構成とした。ＮｉＣｒ層形成の際には、スパッタガスとしてアルゴンガスを用い、総ガス圧０．７Ｐａとした。Ｒｕ層は二層に分けて形成した。下層８ｎｍは製膜レート２ｎｍ／ｓで形成し、スパッタガスにはアルゴンと酸素の混合ガスを用い、総ガス圧０．７Ｐａ、酸素濃度１％とした。上層１０ｎｍは製膜レート１ｎｍ／ｓで形成し、スパッタガスにはアルゴガスを用い、総ガス圧を５Ｐａとした。 [Example 7]
The underlayer 44 for controlling the orientation and segregation has a structure in which a Ni-10 at.% Cr layer is sequentially formed with 9 nm and Ru with 18 nm. When forming the NiCr layer, argon gas was used as the sputtering gas, and the total gas pressure was 0.7 Pa. The Ru layer was formed in two layers. The lower layer 8 nm was formed at a film forming rate of 2 nm / s, a mixed gas of argon and oxygen was used as the sputtering gas, the total gas pressure was 0.7 Pa, and the oxygen concentration was 1%. The upper layer 10 nm was formed at a film formation rate of 1 nm / s, the argon gas was used as the sputtering gas, and the total gas pressure was 5 Pa.

グラニュラー磁性層４５は、［６１at.%Ｃｏ−２１at.%Ｃｒ−１８at.%Ｐｔ］とＳｉＯ₂を９３ｍｏｌ：７ｍｏｌの割合で含有する複合型ターゲットを用い、３ｎｍ／ｓの製膜レートで形成した。膜厚は１２．９ｎｍとした。グラニュラー磁性層４５を形成する際には、始めに０．３秒間、総ガス圧６．５Ｐａ、酸素濃度２．５％の条件でアルゴンと酸素の混合ガスを流した後、製膜開始から２．６秒間は総ガス圧を５Ｐａ、酸素濃度を２．７％とし、基板バイアスを−２７５Ｖとした条件で形成し、製膜終了までの１．７秒間は総ガス圧を３．５Ｐａ、酸素濃度を１．０％とし、基板バイアスを−２００Ｖとした条件で形成した。酸化物を含まない強磁性金属層４６には、Ｃｏ−１３at.%Ｃｒ−１６at.%Ｐｔ−１１at.%Ｂ合金、スパッタガスとしてＡｒを用い、総ガス圧を０．６Ｐａとした。膜厚は４ｎｍとした。 The granular magnetic layer 45 was formed at a film forming rate of 3 nm / s using a composite target containing [61 at.% Co-21 at.% Cr-18 at.% Pt] and SiO ₂ at a ratio of 93 mol: 7 mol. . The film thickness was 12.9 nm. When the granular magnetic layer 45 is formed, first, after flowing a mixed gas of argon and oxygen for 0.3 seconds under conditions of a total gas pressure of 6.5 Pa and an oxygen concentration of 2.5%, the film formation is started 2 The film was formed under the conditions that the total gas pressure was 5 Pa, the oxygen concentration was 2.7%, and the substrate bias was −275 V for 6 seconds, and the total gas pressure was 3.5 Pa and oxygen for 1.7 seconds until film formation was completed. The film was formed under the conditions of a concentration of 1.0% and a substrate bias of −200V. For the ferromagnetic metal layer 46 not containing an oxide, a Co-13 at.% Cr-16 at.% Pt-11 at.% B alloy, Ar was used as the sputtering gas, and the total gas pressure was 0.6 Pa. The film thickness was 4 nm.

［実施例８］
グラニュラー磁性層４５は、［６１at.%Ｃｏ−２１at.%Ｃｒ−１８at.%Ｐｔ］とＳｉＯ₂を９３ｍｏｌ：７ｍｏｌの割合で含有する複合型ターゲットを用い、３ｎｍ／ｓの製膜レートで基板バイアスを−２７５Ｖとした条件で形成した。膜厚は１２．９ｎｍとした。グラニュラー磁性層４５を形成する際には、始めに０．３秒間、総ガス圧６．５Ｐａ、酸素濃度２．５％の条件でアルゴンと酸素の混合ガスを流した後、製膜開始から製膜終了まで総ガス圧を５Ｐａ、酸素濃度を２．７％とした。酸化物を含まない強磁性金属層４６には、Ｃｏ−１３at.%Ｃｒ−１６at.%Ｐｔ−１１at.%Ｂ合金ターゲットを用い、スパッタガスとしてＡｒを用い、総ガス圧を０．６Ｐａとした。膜厚は６ｎｍとした。 [Example 8]
The granular magnetic layer 45 uses a composite target containing [61 at.% Co-21 at.% Cr-18 at.% Pt] and SiO ₂ at a ratio of 93 mol: 7 mol, and a substrate bias at a film formation rate of 3 nm / s. Was formed under the condition of −275V. The film thickness was 12.9 nm. When the granular magnetic layer 45 is formed, first, a mixed gas of argon and oxygen is flowed for 0.3 seconds under conditions of a total gas pressure of 6.5 Pa and an oxygen concentration of 2.5%, and then the film formation is started. The total gas pressure was 5 Pa and the oxygen concentration was 2.7% until the end of the film. For the ferromagnetic metal layer 46 containing no oxide, a Co-13 at.% Cr-16 at.% Pt-11 at.% B alloy target was used, Ar was used as the sputtering gas, and the total gas pressure was 0.6 Pa. . The film thickness was 6 nm.

グラニュラー磁性層４５、及び強磁性金属層４６以外は実施例７と同一条件とした。 The conditions were the same as in Example 7 except for the granular magnetic layer 45 and the ferromagnetic metal layer 46.

［比較例１］
グラニュラー磁性層４５は、［７０at.%Ｃｏ−１２at.%Ｃｒ−１８at.%Ｐｔ］とＳｉＯ₂を８９ｍｏｌ：１１ｍｏｌの割合で含有する複合型ターゲットを用い、３ｎｍ／ｓの製膜レートで基板バイアスを−２００Ｖとした条件で形成した。膜厚は１２．９ｎｍとした。グラニュラー磁性層４５を形成する際には、始めに０．３秒間、総ガス圧６．５Ｐａ、酸素濃度２．５％の条件でアルゴンと酸素の混合ガスを流した後、製膜開始から２．３秒間は総ガス圧を５Ｐａ、酸素濃度を１．３％とし、製膜終了までの１．９秒間は総ガス圧を３．５Ｐａ、酸素濃度を０％とした。酸化物を含まない強磁性金属層４６を形成する際には、Ｃｏ−１５at.%Ｃｒ−１４at.%Ｐｔ−８at.%Ｂ合金ターゲットを用い、スパッタガスとしてＡｒを用い、総ガス圧を０．６Ｐａとした。膜厚は７ｎｍとした。 [Comparative Example 1]
The granular magnetic layer 45 uses a composite target containing [70 at.% Co-12 at.% Cr-18 at.% Pt] and SiO ₂ at a ratio of 89 mol: 11 mol, and a substrate bias at a film formation rate of 3 nm / s. Was formed under the condition of −200V. The film thickness was 12.9 nm. When the granular magnetic layer 45 is formed, first, after flowing a mixed gas of argon and oxygen for 0.3 seconds under conditions of a total gas pressure of 6.5 Pa and an oxygen concentration of 2.5%, the film formation is started 2 The total gas pressure was 5 Pa and the oxygen concentration was 1.3% for 3 seconds, and the total gas pressure was 3.5 Pa and the oxygen concentration was 0% for 1.9 seconds until film formation was completed. When forming the ferromagnetic metal layer 46 containing no oxide, a Co-15 at.% Cr-14 at.% Pt-8 at.% B alloy target is used, Ar is used as the sputtering gas, and the total gas pressure is 0. .6 Pa. The film thickness was 7 nm.

グラニュラー磁性層４５、及び強磁性金属層４６以外は、すべて実施例１と同様にして作製した。 Except for the granular magnetic layer 45 and the ferromagnetic metal layer 46, all were produced in the same manner as in Example 1.

［比較例２］
配向と偏析を制御する下地層４４に含まれるＮｉＣｒＷ層の膜厚を４ｎｍとした以外は、比較例１と同様のサンプルを作製した。 [Comparative Example 2]
A sample similar to Comparative Example 1 was produced except that the thickness of the NiCrW layer included in the underlayer 44 for controlling the orientation and segregation was 4 nm.

［比較例３］
グラニュラー磁性層４５は、［７０at.%Ｃｏ−１２at.%Ｃｒ−１８at.%Ｐｔ］とＳｉＯ₂を８９ｍｏｌ：１１ｍｏｌの割合で含有する複合型ターゲットを用い、３ｎｍ／ｓの製膜レートで基板バイアスを−２００Ｖとした条件で膜厚９．９ｎｍ形成後、続けて［５９at.%Ｃｏ−２３at.%Ｃｒ−１８at.%Ｐｔ］とＳｉＯ₂を９５ｍｏｌ：５ｍｏｌの割合で含有する複合型ターゲットを用い、３ｎｍ／ｓの製膜レートで基板バイアス−２７５Ｖの条件で膜厚３ｎｍ形成した。 [Comparative Example 3]
The granular magnetic layer 45 uses a composite target containing [70 at.% Co-12 at.% Cr-18 at.% Pt] and SiO ₂ at a ratio of 89 mol: 11 mol, and a substrate bias at a film formation rate of 3 nm / s. After forming a film thickness of 9.9 nm under the condition of −200 V, a composite target containing [59 at.% Co-23 at.% Cr-18 at.% Pt] and SiO ₂ at a ratio of 95 mol: 5 mol was used. A film thickness of 3 nm was formed at a film formation rate of 3 nm / s and a substrate bias of −275 V.

グラニュラー磁性層４５の前半９．９ｎｍを形成する際には、始めに０．３秒間、総ガス圧６．５Ｐａ、酸素濃度１．３％の条件でアルゴンと酸素の混合ガスを流した後、製膜開始から２．８秒間は総ガス圧を５Ｐａ、酸素濃度を１．３％とし、製膜終了までの０．５秒間は総ガス圧を３．５Ｐａ、酸素濃度を０％とした。グラニュラー磁性層４５の後半３ｎｍを形成する際には、Ａｒガスのみを用い、総ガス圧を３．５Ｐａとした。酸化物を含まない強磁性金属層４６を形成する際には、Ｃｏ−２２at.%Ｃｒ−１４at.%Ｐｔ合金ターゲットを用い、スパッタガスとしてＡｒを用い、総ガス圧を０．６Ｐａとし、膜厚は６ｎｍとした。 When forming the first 9.9 nm of the granular magnetic layer 45, first, after flowing a mixed gas of argon and oxygen under the conditions of a total gas pressure of 6.5 Pa and an oxygen concentration of 1.3% for 0.3 seconds, The total gas pressure was 5 Pa and the oxygen concentration were 1.3% for 2.8 seconds from the start of film formation, and the total gas pressure was 3.5 Pa and the oxygen concentration was 0% for 0.5 seconds until the end of film formation. When forming the latter half 3 nm of the granular magnetic layer 45, only Ar gas was used and the total gas pressure was 3.5 Pa. When forming the ferromagnetic metal layer 46 containing no oxide, a Co-22 at.% Cr-14 at.% Pt alloy target is used, Ar is used as the sputtering gas, the total gas pressure is 0.6 Pa, The thickness was 6 nm.

グラニュラー磁性層４５、及び強磁性金属層４６以外は、実施例８と同一条件とした。 The conditions were the same as in Example 8 except for the granular magnetic layer 45 and the ferromagnetic metal layer 46.

［比較例４］
グラニュラー磁性層４５の前半９．９ｎｍで、［７０at.%Ｃｏ−１２at.%Ｃｒ−１８at.%Ｐｔ］とＴａ₂Ｏ₅を９６ｍｏｌ：４ｍｏｌの割合で含有する複合型ターゲットを用いたこと以外、比較例３と同一条件とした。 [Comparative Example 4]
In the first half of the granular magnetic layer 45, a composite target containing [70 at.% Co-12 at.% Cr-18 at.% Pt] and Ta ₂ O ₅ in a ratio of 96 mol: 4 mol was used. The conditions were the same as in Comparative Example 3.

［比較例５］
グラニュラー磁性層４５の前半９．９ｎｍで、［７０at.%Ｃｏ−１２at.%Ｃｒ−１８at.%Ｐｔ］とＮｂ₂Ｏ₅を９６ｍｏｌ：４ｍｏｌの割合で含有する複合型ターゲットを用いたこと以外、比較例３と同一条件とした。 [Comparative Example 5]
Other than using a composite target containing [70 at.% Co-12 at.% Cr-18 at.% Pt] and Nb ₂ O ₅ in a ratio of 96 mol: 4 mol in the first 9.9 nm of the granular magnetic layer 45, The conditions were the same as in Comparative Example 3.

［比較例６］
グラニュラー磁性層４５の前半９．９ｎｍで、［７０at.%Ｃｏ−１２at.%Ｃｒ−１８at.%Ｐｔ］とＴｉＯ₂を８９ｍｏｌ：１１ｍｏｌの割合で含有する複合型ターゲットを用いたこと以外、比較例３と同一条件とした。 [Comparative Example 6]
Comparative example except that the first half of the granular magnetic layer 45 was 9.9 nm and a composite target containing [70 at.% Co-12 at.% Cr-18 at.% Pt] and TiO ₂ at a ratio of 89 mol: 11 mol was used. 3 and the same conditions.

［比較例７］
グラニュラー磁性層４５は、［６５at.%Ｃｏ−１７at.%Ｃｒ−１８at.%Ｐｔ］とＳｉＯ₂を９２ｍｏｌ：８ｍｏｌの割合で含有する複合型ターゲットを用い、３ｎｍ／ｓの製膜レートで基板バイアスを−１００Ｖとした条件で形成した。膜厚は１２．９ｎｍとした。グラニュラー磁性層４５を形成する際には、始めに０．３秒間、総ガス圧６．５Ｐａ、酸素濃度２．５％の条件でアルゴンと酸素の混合ガスを流した後、製膜開始から製膜終了まで総ガス圧を５Ｐａ、酸素濃度を１．７％とした。酸化物を含まない強磁性金属層４６には、Ｃｏ−１３at.%Ｃｒ−１６at.%Ｐｔ−１１at.%Ｂ合金、スパッタガスとしてＡｒを用い、総ガス圧を０．６Ｐａとした。膜厚は６ｎｍとした。 [Comparative Example 7]
The granular magnetic layer 45 uses a composite target containing [65 at.% Co-17 at.% Cr-18 at.% Pt] and SiO ₂ at a ratio of 92 mol: 8 mol, and a substrate bias at a film formation rate of 3 nm / s. Was formed under the condition of −100V. The film thickness was 12.9 nm. When the granular magnetic layer 45 is formed, first, a mixed gas of argon and oxygen is flowed for 0.3 seconds under conditions of a total gas pressure of 6.5 Pa and an oxygen concentration of 2.5%, and then the film formation is started. The total gas pressure was 5 Pa and the oxygen concentration was 1.7% until the end of the film. For the ferromagnetic metal layer 46 containing no oxide, a Co-13 at.% Cr-16 at.% Pt-11 at.% B alloy, Ar was used as the sputtering gas, and the total gas pressure was 0.6 Pa. The film thickness was 6 nm.

グラニュラー磁性層４５、及び強磁性金属層４６以外は実施例８と同一条件とした。 The conditions were the same as in Example 8 except for the granular magnetic layer 45 and the ferromagnetic metal layer 46.

［比較例８］
配向と偏析を制御する下地層４４に含まれるＮｉＣｒ層の膜厚を４ｎｍとした以外は、比較例７と同様のサンプルを作製した。 [Comparative Example 8]
A sample similar to Comparative Example 7 was produced except that the thickness of the NiCr layer included in the underlayer 44 for controlling orientation and segregation was changed to 4 nm.

上記実施例１〜実施例８及び比較例１〜比較例８において、強磁性金属層４６の膜厚はほぼ同等の記録能力が得られるように設定した。 In Examples 1 to 8 and Comparative Examples 1 to 8, the film thickness of the ferromagnetic metal layer 46 was set so as to obtain almost the same recording ability.

上述のようにして得られた実施例１から実施例８と比較例１から比較例８の垂直磁気記録媒体について、磁気特性、記録再生特性、微細構造評価を行った。表１にその結果を示す。 The perpendicular magnetic recording media of Examples 1 to 8 and Comparative Examples 1 to 8 obtained as described above were evaluated for magnetic characteristics, recording / reproducing characteristics, and fine structure. Table 1 shows the results.

磁気特性評価には、Kerr効果測定装置を用いた。測定波長は３５０ｎｍ、レーザーのスポット径は約１ｍｍである。磁界は試料膜面垂直方向に印加し、最大磁界は１５８０ｋＡ／ｍ（２０ｋＯｅ）とし、掃引速度を一定として６０秒間でカーループの測定を行った。その後、保磁力（Ｈｃ）、逆磁区核形成磁界（−Ｈｎ）を求めた。−Ｈｎは、Kerr回転角が正に飽和した状態から磁界を下げた時に飽和値の９５％となるときの磁界とし、第二象限にある場合を正と定義した。 A Kerr effect measuring device was used for magnetic property evaluation. The measurement wavelength is 350 nm, and the laser spot diameter is about 1 mm. The magnetic field was applied in the direction perpendicular to the sample film surface, the maximum magnetic field was set to 1580 kA / m (20 kOe), and the Kerr loop was measured for 60 seconds at a constant sweep rate. Thereafter, coercive force (Hc) and reverse domain nucleation magnetic field (-Hn) were determined. -Hn was defined as a magnetic field when 95% of the saturation value was obtained when the magnetic field was lowered from a state in which the Kerr rotation angle was positively saturated, and positive in the second quadrant.

記録再生特性評価にはスピンスタンドを用い、周速１１．８８ｍ／ｓ、スキュー角０度、磁気スペーシング約８ｎｍの条件で行った。媒体Ｓ／Ｎは、２７１２６ｆｒ／ｍｍの線記録密度における再生出力と上記線記録密度で信号を記録した時の積分ノイズの比によって評価した。ＯＷ特性は、２７１２６ｆｒ／ｍｍの信号の上に２７１３ｆｒ／ｍｍの信号を重ね書きした後の記録密度２７１２６ｆｒ／ｍｍの信号の消え残り成分と２７１３ｆｒ／ｍｍの信号強度の比を用いて評価した。磁気ヘッドの再生部には、シールドギャップ長６０ｎｍ、トラック幅７０ｎｍのトンネル磁気抵抗効果（ＴＭＲ）を利用した再生素子を用いた。磁気ヘッドの記録部は、主磁極と補助磁極と薄膜導体コイルを有する単磁極型ヘッドの構造を有し、主磁極は主磁極ヨーク部と主磁極先端部からなり、主磁極先端部のトラック幅方向及びダウントラック方向を覆うようにシールドが形成されている（ラップアラウンドシールドヘッド）。主磁極先端部の幾何学的なトラック幅９０ｎｍ、主磁極−トレーリングシールド間の距離５０ｎｍ、主磁極−サイドシールド間距離１００ｎｍのヘッドを用いた。 The recording / reproduction characteristics were evaluated using a spin stand under conditions of a peripheral speed of 11.88 m / s, a skew angle of 0 degree, and a magnetic spacing of about 8 nm. The medium S / N was evaluated by the ratio of the reproduction output at a linear recording density of 27126 fr / mm and the integrated noise when the signal was recorded at the linear recording density. The OW characteristics were evaluated by using the ratio of the remaining signal component of the recording density 27126 fr / mm to the signal strength of 2713 fr / mm after the 2713 fr / mm signal was overwritten on the 27126 fr / mm signal. A reproducing element using a tunnel magnetoresistance effect (TMR) having a shield gap length of 60 nm and a track width of 70 nm was used for the reproducing portion of the magnetic head. The recording part of the magnetic head has a structure of a single magnetic pole type head having a main magnetic pole, an auxiliary magnetic pole, and a thin film conductor coil. The main magnetic pole is composed of a main magnetic pole yoke part and a main magnetic pole tip part, and the track width of the main magnetic pole tip part A shield is formed so as to cover the direction and the down track direction (wraparound shield head). A head having a geometric track width of 90 nm at the tip of the main pole, a distance between the main pole and the trailing shield of 50 nm, and a distance between the main pole and the side shield of 100 nm was used.

隣接トラック消去は、あるトラックにデータを１回記録した後の隣接トラックのビット誤り率ＢＥＲ（１回）と、あるトラックにデータを１００００回記録した後の隣接トラックのビット誤り率ＢＥＲ（１００００回）を測定し、その比の対数Log₁₀（ＢＥＲ（１００００回）／ＢＥＲ（１回））を、隣接トラックにおけるビット誤り率の劣化量（隣接トラック消去）とした。 In the adjacent track erasing, the bit error rate BER (1 time) of the adjacent track after data is recorded once in a track and the bit error rate BER (10000 times) of the adjacent track after data is recorded 10,000 times in a track. ) Was measured, and the logarithm Log ₁₀ (BER (10000 times) / BER (1 time)) of the ratio was taken as the amount of bit error rate degradation (adjacent track erasure) in the adjacent track.

媒体の微細構造評価には、透過型電子顕微鏡（ＴＥＭ）を用いた。グラニュラー磁性層の規格化粒界幅の分散を求める際には、研磨とＡｒイオンミリングにより、基板側及び表面側からほぼグラニュラー磁性層のみが含まれる状態まで極薄膜化し、平面ＴＥＭ像から５００ｎｍ×５００ｎｍ以上の領域に含まれる磁性粒子の観察を行った。ここで、磁性粒子の面積重心を求め、重心同士を結んだ線が他の結晶粒子を跨がないものを隣接する磁性粒子と定義し、グラニュラー磁性層のある強磁性粒子に隣接する強磁性粒子の面積重心を結んだ線によって囲まれる領域に含まれる磁性粒子の面積をＡ＿ｇ、粒界の面積をA_bと定義した時、グラニュラー磁性層中の規格化粒界面積A_b／A_g+bの分散を求めた。また、磁性粒子の面積重心を結んだ線と粒界の交わる長さから求めた粒界幅の平均値を求めた。グラニュラー磁性層の磁性粒子の平均粒径は、上記領域に含まれる磁性粒子の面積を平均化し、その平均面積と等しい面積を持つ円の直径として平均粒径を求めた。グラニュラー層表層と下層から中央の粒界幅の差は、断面ＴＥＭ像から１００個程度の粒界を抽出し、各々の粒界においてグラニュラー磁性層の膜厚方向に１ｎｍ刻みで分割し、グラニュラー磁性層表層２ｎｍと下層から中央の粒界の幅をそれぞれ求め、その平均値の差から算出した。 A transmission electron microscope (TEM) was used for evaluation of the fine structure of the medium. When obtaining the dispersion of the normalized grain boundary width of the granular magnetic layer, by polishing and Ar ion milling, an extremely thin film is formed from the substrate side and the surface side to a state almost including only the granular magnetic layer, and a 500 nm × The magnetic particles contained in the region of 500 nm or more were observed. Here, the area centroid of the magnetic particle is obtained, and the magnetic particle adjacent to the ferromagnetic particle having the granular magnetic layer is defined as an adjacent magnetic particle in which the line connecting the centroids does not straddle other crystal particles. When the area of the magnetic particles contained in the region surrounded by the line connecting the center of gravity of the area is defined as A_g and the area of the grain boundary as A_b, the dispersion of the normalized grain boundary area A_b / A_g + b in the granular magnetic layer is Asked. Moreover, the average value of the grain boundary width calculated | required from the length which the line which connected the area gravity center of the magnetic particle and the grain boundary crossed was calculated | required. The average particle size of the magnetic particles in the granular magnetic layer was obtained by averaging the areas of the magnetic particles contained in the region and calculating the average particle size as the diameter of a circle having an area equal to the average area. The difference in the grain boundary width between the surface layer and the lower layer of the granular layer is obtained by extracting about 100 grain boundaries from the cross-sectional TEM image and dividing the grain boundaries in the thickness direction of the granular magnetic layer at each grain boundary. The width of the grain boundary at the center was obtained from the surface layer of 2 nm and the lower layer, and calculated from the difference between the average values.

上記実施例１から実施例８及び比較例１から比較例８において、ＯＷ値は３５〜４０ｄＢとほぼ同等で、十分な値を有していることが確認された。また、Ｘ線回折装置を用いて上記媒体のグラニュラー磁性層の結晶配向を調べたところ、ｈｃｐ構造を有し、（０００１）が優先配向していることがわかった。 In Example 1 to Example 8 and Comparative Example 1 to Comparative Example 8, it was confirmed that the OW value was substantially equivalent to 35 to 40 dB and had a sufficient value. Further, when the crystal orientation of the granular magnetic layer of the medium was examined using an X-ray diffractometer, it was found that it had an hcp structure and (0001) was preferentially oriented.

図３に、規格化粒界面積A_b／A_g+bの分散とＳ／Ｎの関係を示す。本実施例のサンプルは、規格化粒界面積A_b／A_g+bの分散が３０％以下と小さく、比較例のサンプルに比べて、１ｄＢ以上高いＳ／Ｎを示すことがわかる。 FIG. 3 shows the relationship between the dispersion of the normalized grain interface area A_b / A_g + b and the S / N. It can be seen that the sample of this example has a dispersion of the normalized grain interface area A_b / A_g + b as small as 30% or less, and exhibits an S / N higher by 1 dB or more than the sample of the comparative example.

実施例１、２及び比較例１〜３を比較すると、本実施例のサンプルは強磁性粒子の粒径では約１ｎｍ程度大きく、平均粒界幅では同等か０．５ｎｍ程度小さいにもかかわらず、約２〜３ｄＢ高いＳ／Ｎ比を示している。このことは、単純に平均粒径を微細化し、平均粒界幅を広げても、必ずしもＳ／Ｎが向上しないことを示している。一例として実施例１のサンプルと比較例２のサンプルのグラニュラー磁性層４５の平面構造の模式図を図４及び図５に示す。 Comparing Examples 1 and 2 and Comparative Examples 1 to 3, the sample of this example is about 1 nm larger in the particle size of the ferromagnetic particles, although the average grain boundary width is equal or smaller than about 0.5 nm, A high S / N ratio of about 2-3 dB is shown. This indicates that S / N is not necessarily improved even if the average grain size is simply made finer and the average grain boundary width is increased. As an example, schematic views of the planar structure of the granular magnetic layer 45 of the sample of Example 1 and the sample of Comparative Example 2 are shown in FIGS.

規格化粒界面積A_b／A_g+bの分散が２１％と小さい実施例１のサンプルは、サブグレインが殆ど無く、強磁性粒子を取り囲む非磁性粒界幅の変動が小さく、粒界が交わる部分でも非磁性物質の溜まりが殆ど見られない。規格化粒界面積A_b／A_g+bの分散が３０％以下の本実施例のグラニュラー磁性層は、下地層の材料やグラニュラー磁性層、強磁性金属層の材料を変えても、図４のようにサブグレインが殆ど無く、強磁性粒子を取り囲む非磁性粒界幅の変動が小さく、粒界が交わる部分に大きな非磁性物質の溜まりが少ない構造を有していた。規格化粒界面積A_b／A_g+bの分散を３０％以下とすることで、交換結合の分散を低減できるため、平均粒界幅が０．５ｎｍと比較的小さい値でも交換結合を均一に低減でき、また、強磁性結晶粒子の充填率が上がり、高いＳ／Ｎが得られたと考えられる。また、表１より、本実施例の媒体の方がＨｃ、Ｈｎが大きく熱安定性に優れていることがわかる。これは、粒界幅が均一であるため、強磁性結晶粒子の粒径を大きく設定できるためである。 In the sample of Example 1 where the dispersion of the normalized grain interface area A_b / A_g + b is as small as 21%, there is almost no subgrain, the fluctuation of the nonmagnetic grain boundary width surrounding the ferromagnetic grain is small, and the part where the grain boundary intersects However, there is almost no accumulation of non-magnetic substances. The granular magnetic layer of this example having a normalized grain boundary area A_b / A_g + b dispersion of 30% or less is shown in FIG. 4 even if the material of the underlayer, the granular magnetic layer, or the ferromagnetic metal layer is changed. 3 had almost no subgrains, had a small variation in the width of the nonmagnetic grain boundary surrounding the ferromagnetic particles, and had a structure in which a large amount of nonmagnetic substances remained in the intersection of the grain boundaries. Since the dispersion of exchange coupling can be reduced by setting the dispersion of the normalized grain interface area A_b / A_g + b to 30% or less, the exchange coupling is uniformly reduced even when the average grain boundary width is 0.5 nm. It is also possible that the packing rate of the ferromagnetic crystal particles was increased and a high S / N was obtained. Further, it can be seen from Table 1 that the medium of this example has larger Hc and Hn and better thermal stability. This is because the grain boundary width is uniform and the grain size of the ferromagnetic crystal grains can be set large.

実施例６と実施例８の比較から、規格化粒界面積A_b／A_g+bの分散が２５％と同じ場合、強磁性結晶粒の平均粒径と平均粒界幅の和（平均重心間距離）が同じ場合、平均粒界幅が０．６ｎｍから１ｎｍと広がると僅かにＳ／Ｎが減少する様子が見られている。これは、強磁性粒子の充填率が落ちたことで、出力の低下や、ジッター性のノイズの増加が起きたためと考えられる。 From the comparison between Example 6 and Example 8, when the dispersion of the normalized grain interface area A_b / A_g + b is the same as 25%, the sum of the average grain size and the average grain boundary width of the ferromagnetic crystal grains (average distance between the centers of gravity) ), The S / N ratio is slightly reduced when the average grain boundary width increases from 0.6 nm to 1 nm. This is thought to be due to a decrease in output and an increase in jitter noise due to a decrease in the packing rate of the ferromagnetic particles.

一方、規格化粒界面積A_b／A_g+bの分散が４４％と大きい、比較例２では、強磁性粒子を取り囲む非磁性粒界幅の変動が大きく、粒界が交わる部分で大きな非磁性物質の溜まりが数多く見られる一方で、粒界幅の狭いサブグレインも多数観察された。規格化粒界面積A_b／A_g+bの分散が３０％より大きな比較例においては、すべて同様の傾向が見られた。このように規格化粒界面積A_b／A_g+bの分散が３０％より大きな場合には、平均的な粒界幅が広くても、粒界幅が狭い部分が多数存在し、そこを介して交換結合が働くため、交換結合の分散が非常に大きくなる。強磁性粒子の粒径は小さくても、より広い範囲に交換結合が及んで、磁化反転単位が大きくなってしまったことがＳ／Ｎ劣化の原因と考えられる。これに加えて、非磁性物質が粒界の交点に大きな溜まりとして多数存在することで、強磁性粒子の充填率が落ちたこともＳ／Ｎ劣化の原因と考えられる。 On the other hand, the dispersion of the normalized grain interface area A_b / A_g + b is as high as 44%. In Comparative Example 2, the nonmagnetic grain boundary width surrounding the ferromagnetic grains is large, and the nonmagnetic substance is large at the intersection of the grain boundaries. While many reservoirs were observed, many subgrains with narrow grain boundaries were also observed. The same tendency was observed in all the comparative examples in which the dispersion of the normalized grain interface area A_b / A_g + b was larger than 30%. In this way, when the dispersion of the normalized grain boundary area A_b / A_g + b is larger than 30%, even if the average grain boundary width is wide, there are many portions where the grain boundary width is narrow. Since exchange coupling works, the dispersion of exchange coupling becomes very large. Even if the particle size of the ferromagnetic particles is small, it is considered that the exchange coupling reaches a wider range and the magnetization reversal unit becomes large, which causes the S / N deterioration. In addition to this, it is considered that the S / N deterioration is caused by a decrease in the filling rate of the ferromagnetic particles due to the presence of a large number of nonmagnetic substances as large pools at the intersections of the grain boundaries.

光電子分光法（ＸＰＳ）を用い、上記サンプルのグラニュラー磁性層の組成分析を行った。加速電圧５００Ｖのイオン銃でサンプル表面からスパッタして深さ方向に掘り進み、アルミニウムのＫα線をエックス線源として、長さ１．５ｍｍで幅０．１ｍｍの範囲を分析した。Ｃの１ｓ電子、Ｏの１ｓ電子、Ｓｉの２ｓ電子、Ｃｒの２ｐ電子、Ｃｏの２ｐ電子、Ｒｕの３ｄ電子、Ｐｔの４ｆ電子などに対応するエネルギー近傍のスペクトルを検出することにより、各元素の含有率を求めた。例えばＣｒ酸化物の量を求める際には、Ｃｒのスペクトルの化学シフトから金属のＣｒとＣｒ酸化物の割合を求めた。 Composition analysis of the granular magnetic layer of the above sample was performed using photoelectron spectroscopy (XPS). The sample was sputtered from the surface of the sample with an ion gun with an acceleration voltage of 500 V and digged in the depth direction, and an aluminum Kα ray was used as an X-ray source to analyze a range of 1.5 mm in length and 0.1 mm in width. Each element is detected by detecting spectra in the vicinity of energy corresponding to 1s electrons of C, 1s electrons of O, 2s electrons of Si, 2p electrons of Cr, 2p electrons of Co, 3d electrons of Ru, 4f electrons of Pt, etc. The content of was determined. For example, when obtaining the amount of Cr oxide, the ratio of metallic Cr to Cr oxide was obtained from the chemical shift of the Cr spectrum.

本実施例のサンプルは、グラニュラー初期層に、Ｓｉ，Ｔｉ，Ｔａ，Ｎｂなどの酸化物生成自由エネルギーの高い酸化物に加えてＣｒ酸化物を構成するＣｒ元素と酸素元素の和は７at.%以上であったのに対し、比較例のサンプルではＳｉ，Ｔｉ，Ｔａ，Ｎｂなどの酸化物生成自由エネルギーの高い酸化物が実施例に比べて多く存在し、Ｃｒ酸化物は６at.%以下と少なかった。 In the sample of this example, the sum of the Cr element and the oxygen element constituting the Cr oxide in addition to the oxide having a high free energy for generating an oxide such as Si, Ti, Ta, and Nb is 7 at.% In the granular initial layer. In contrast to the above, in the sample of the comparative example, there are many oxides with high free energy of oxide generation such as Si, Ti, Ta, Nb, etc. as compared with the examples, and the Cr oxide is 6 at.% Or less. There were few.

透過電子顕微鏡（ＴＥＭ）に電子エネルギー損失分光法（ＥＥＬＳ）を組み合わせたＴＥＭ−ＥＥＬＳで粒界部の組成を分析したところ、本実施例のグラニュラー磁性層の初期部分の粒界にはＳｉ，Ｔｉ，Ｔａ，Ｎｂなどの酸化物生成自由エネルギーの大きな元素に加えてＣｒとＯ（酸素）が多く存在することが確認されたのに対し、比較例ではＣｒ元素はあまり観察されなかった。 When the composition of the grain boundary part was analyzed by TEM-EELS in which the electron energy loss spectroscopy (EELS) was combined with the transmission electron microscope (TEM), the initial part of the granular magnetic layer of this example had Si, Ti In addition to the elements with large free energy for oxide formation such as, Ta and Nb, it was confirmed that a large amount of Cr and O (oxygen) was present, whereas in the comparative example, not much Cr element was observed.

初期層にＣｒ酸化物を多く含む本実施例のサンプルでは、Ｃｒ酸化物が粒界に偏析することで均一な幅の結晶粒界が形成されたと考えられる。一方、Ｓｉ，Ｔｉ，Ｔａ，Ｎｂなどの酸化物生成自由エネルギーの大きな元素の酸化物のみが多い場合には、サブグレインが多数形成されたり、粒界が交わる部分に酸化物が大きく析出したりして、粒界幅の分布が生じたり、強磁性粒子の充填率も低下したりすることがわかった。 In the sample of this example in which the initial layer contains a large amount of Cr oxide, it is considered that the crystal grain boundary having a uniform width was formed by the segregation of Cr oxide at the grain boundary. On the other hand, when there are only a large number of oxides of elements having a large free energy for oxide generation such as Si, Ti, Ta, Nb, etc., a large number of subgrains are formed or a large amount of oxides are deposited at the intersections of grain boundaries. As a result, it was found that the distribution of the grain boundary width occurs and the filling rate of the ferromagnetic particles also decreases.

比較例７と８では、比較例１〜３に比べて初期層に含まれるＣｒ酸化物が増えて、Ｓｉ酸化物の量が抑えられているため、サブグレインの発生割合や、粒界幅の分散は抑えられてきているが、粒界の交わる部分にはまだ酸化物の溜まりが多くみられており、これがA_b／A_g+bの分散を増加させる要因となっている。粒界の交わる部分の酸化物の溜まりは、強磁性粒子の充填率を下げるため、Ｓ／Ｎの劣化につながったと考えられる。 In Comparative Examples 7 and 8, since the amount of Cr oxide contained in the initial layer is increased and the amount of Si oxide is suppressed as compared with Comparative Examples 1 to 3, the generation rate of subgrains and the grain boundary width are reduced. Dispersion has been suppressed, but there are still many oxide pools at the intersections of grain boundaries, which is a factor that increases the dispersion of A_b / A_g + b. It is considered that the accumulation of oxides at the intersections of the grain boundaries led to the deterioration of S / N because the filling rate of the ferromagnetic particles was lowered.

実施例７と実施例８を比較した場合、グラニュラー磁性層形成時の後半を酸素なしで形成した実施例７では、グラニュラー磁性層表面側でＣｒ酸化物を構成する元素の濃度の和がグラニュラー磁性層中心付近の３０％以下まで急激に減少していたのに対し、後半も同じ酸素濃度で形成した実施例８ではＣｒ酸化物を構成する元素の濃度の和はグラニュラー磁性層表面側と中心付近とほとんど変わらなかった。実施例７と８は３６ｄＢと同等のＯＷ特性を示すが、実施例８では強磁性金属層の厚さを２ｎｍ厚くする必要があった。これによって、分解能が劣化したことで０．２ｄＢのＳ／Ｎの劣化が見られた。これら二種類のサンプルを、１ｃｍあたり５．１２×１０⁵ビット（５１２ｋbit/cm，１３００ｋbit/inch）の線記録密度におけるビット誤り率（ＢＥＲ：１０⁸ビットのデータを読み出したときの（誤りビット数）／（読み出しビット数））を測定したとろ、ＢＥＲは１０^-5.4及び１０^-5.2（Log₁₀（ＢＥＲ）＝−５．４及び−５．２）であった。 When Example 7 and Example 8 are compared, in Example 7 in which the latter half of the formation of the granular magnetic layer is formed without oxygen, the sum of the concentrations of the elements constituting the Cr oxide on the surface side of the granular magnetic layer is the granular magnetism. In Example 8 formed at the same oxygen concentration in the latter half, the sum of the concentrations of the elements constituting the Cr oxide was near the center of the granular magnetic layer and near the center. It was almost the same. Examples 7 and 8 show OW characteristics equivalent to 36 dB, but in Example 8, it was necessary to increase the thickness of the ferromagnetic metal layer by 2 nm. As a result, the S / N degradation of 0.2 dB was observed due to the degradation of the resolution. The bit error rate (BER: 10 ⁸ bit data at the time of reading out data of BER: 10 ⁸ bits at a linear recording density of 5.12 × 10 ⁵ bits per 1 cm (512 kbit / cm, 1300 kbit / inch). ) / (Number of read bits)), the BER was 10 ^−5.4 and 10 ^−5.2 (Log ₁₀ (BER) = − 5.4 and −5.2).

この線記録密度において、トラック間隔を変えて複数のトラックに情報を記録した際、ビット誤り率が１０^-3以下となるオフトラック許容量が、前記トラック間隔の３０％となるときのトラック間隔よりトラック密度を算出したところ、トラックピッチはおおよそ１ｃｍあたり８．６６×１０⁴トラック（８６．６ｋtrack/cm，２２０ｋtrack/inch）であった。上記の方法で求めたトラック密度で、あるトラックにデータを１回記録した後の隣接トラックのビット誤り率ＢＥＲ（１回）と、あるトラックにデータを１００００回記録した後の隣接トラックのビット誤り率ＢＥＲ（１００００回）を測定し、隣接トラックにおけるビット誤り率の劣化量（隣接トラック消去）を、その比の対数Log₁₀（ＢＥＲ（１００００回）／ＢＥＲ（１回））から求めた。表１に示すように、強磁性金属層の厚い実施例８においては実施例７と比較して、隣接トラックにおけるビット誤り率の劣化量が０．５から１．２へと大幅に劣化することが解った。これは、強磁性金属膜はグラニュラー膜に比べて膜中の交換結合が非常に強いために、膜厚の増加に伴って反転磁界分散は低減されるものの磁気クラスターサイズが急激に増加することにより、隣接トラックの影響を受けやすくなり、隣接トラックにおけるビット誤り率の急激な劣化を生じたと考えられる。 At this linear recording density, when information is recorded on a plurality of tracks at different track intervals, the off-track allowable amount at which the bit error rate is 10 ⁻³ or less is 30% of the track interval. When the track density was calculated, the track pitch was about 8.66 × 10 ⁴ tracks (86.6 ktrack / cm, 220 ktrack / inch) per 1 cm. With the track density obtained by the above method, the bit error rate BER (1 time) of the adjacent track after data is recorded once on a track and the bit error of the adjacent track after data is recorded 10,000 times on a track. The rate BER (10000 times) was measured, and the bit error rate deterioration amount (adjacent track erasure) in the adjacent track was obtained from the logarithm Log ₁₀ (BER (10000 times) / BER (1 time)) of the ratio. As shown in Table 1, in Example 8 with a thick ferromagnetic metal layer, the bit error rate deterioration amount in the adjacent track is greatly deteriorated from 0.5 to 1.2 as compared with Example 7. I understand. This is because the ferromagnetic metal film has a much stronger exchange coupling in the film than the granular film, and the magnetic cluster size rapidly increases as the film thickness increases, but the switching field dispersion is reduced. It is considered that the bit error rate in the adjacent track is abruptly deteriorated due to the influence of the adjacent track.

隣接トラック消去が１を超えると隣のトラックの情報が消えてしまう確率が上がり、ハードディスクドライブを使用する上で実用上問題を生じる。これを避けるためには、トラック密度を低く設定する必要が生じ、記録密度の低下を招く。 When the adjacent track erasure exceeds 1, the probability that the information on the adjacent track will be lost increases, which causes a practical problem in using the hard disk drive. In order to avoid this, it is necessary to set the track density low, resulting in a decrease in recording density.

実施例７と実施例８の強磁性金属層及びグラニュラー磁性層表面の微細構造を、ＴＥＭにより詳細に評価した。図６に示すように、グラニュラー磁性層表面側のＣｒ酸化物を減少させた実施例７の場合、グラニュラー磁性層表面側粒界幅が下地層側から中心付近に比べて狭まり、強磁性金属層が成長初期段階から連続的に成長し、幅の広い結晶粒界は観察されなかった。一方、図７に示す実施例８のようにＣｒ酸化物がグラニュラー磁性層表面に多く存在する場合は、実施例７に比べてグラニュラー層表面の粒界幅が広く、強磁性金属層の初期層にも磁性層の粒界を反映して結晶粒界が形成され、幅の広い粒界が観察された。 The microstructures of the ferromagnetic metal layer and granular magnetic layer surfaces of Example 7 and Example 8 were evaluated in detail by TEM. As shown in FIG. 6, in the case of Example 7 in which the Cr oxide on the surface side of the granular magnetic layer was reduced, the grain boundary width on the surface side of the granular magnetic layer was narrower than the vicinity of the center from the underlayer side, and the ferromagnetic metal layer However, a wide grain boundary was not observed. On the other hand, when a large amount of Cr oxide exists on the surface of the granular magnetic layer as in Example 8 shown in FIG. 7, the grain boundary width on the surface of the granular layer is wider than that in Example 7, and the initial layer of the ferromagnetic metal layer. In addition, a grain boundary was formed reflecting the grain boundary of the magnetic layer, and a wide grain boundary was observed.

実施例１〜６においても、同様にグラニュラー磁性層表面側の粒界幅の減少が見られ、強磁性金属層の粒子は成長初期段階から連続的に成長し、幅の広い結晶粒界は観察されなかった。表１に、グラニュラー磁性層表面側２ｎｍの粒界幅の平均と下地層側から中心付近までの粒界幅の平均からの減少量を示す。実施例８を除き、本実施例１〜７では表面側で粒界幅が狭くなっているのがわかる。比較例１〜６のサンプルは結晶性が悪く、粒界幅の測定が困難であった。 In Examples 1 to 6, the grain boundary width on the surface side of the granular magnetic layer was similarly reduced, and the grains of the ferromagnetic metal layer grew continuously from the initial growth stage, and a wide grain boundary was observed. Was not. Table 1 shows the amount of decrease from the average of the grain boundary width of 2 nm on the granular magnetic layer surface side and the average of the grain boundary width from the underlayer side to the vicinity of the center. Except for Example 8, in Examples 1-7, it can be seen that the grain boundary width is narrower on the surface side. The samples of Comparative Examples 1 to 6 had poor crystallinity and it was difficult to measure the grain boundary width.

グラニュラー磁性層の表面側の粒界幅を狭めることにより、強磁性金属層の結晶粒子が成長初期段階からグラニュラー磁性層の結晶粒界を跨ぐ形で成長しやすくなることがわかった。その結果、薄い強磁性金属層でも均一な交換結合がグラニュラー磁性層の粒子間に導入されるようになり、磁性層の反転磁界の大きさ及び分散が低減されたと考えられる。また、磁性層の表面側の粒界が均一に狭まることによっても、強磁性金属層に比べると大きさとしては小さいが均一な交換結合が磁性粒子に導入され、磁性層の反転磁界の大きさ及び分散が低減されたと考えられる。 It has been found that by narrowing the grain boundary width on the surface side of the granular magnetic layer, the crystal grains of the ferromagnetic metal layer can easily grow from the initial stage of growth to straddle the grain boundaries of the granular magnetic layer. As a result, even in a thin ferromagnetic metal layer, uniform exchange coupling is introduced between the grains of the granular magnetic layer, and it is considered that the magnitude and dispersion of the reversal magnetic field of the magnetic layer are reduced. In addition, even if the grain boundary on the surface side of the magnetic layer is uniformly narrowed, a uniform exchange coupling is introduced into the magnetic particles which is smaller in size than the ferromagnetic metal layer, but the magnitude of the reversal magnetic field of the magnetic layer. And the dispersion is considered to be reduced.

一方、強磁性金属層の初期層にＣｒの酸化物が多く存在し結晶粒界が広い場合には、強磁性金属層の結晶粒子はグラニュラー磁性層の酸化物からなる粒界上には成長しにくいため、成長初期段階では結晶粒が分離して成長する。その結果、強磁性金属層の結晶粒子間の交換結合は、粒界構造を反映して不均一になる。図７に見られるように強磁性金属層の粒子が連続化し、反転磁界の分散を低減するために必要な強磁性金属層の膜厚が増加したと考えられる。 On the other hand, when a large amount of Cr oxide exists in the initial layer of the ferromagnetic metal layer and the crystal grain boundary is wide, the crystal grain of the ferromagnetic metal layer grows on the grain boundary made of the oxide of the granular magnetic layer. Since it is difficult, crystal grains separate and grow at the initial stage of growth. As a result, exchange coupling between crystal grains of the ferromagnetic metal layer becomes non-uniform reflecting the grain boundary structure. As seen in FIG. 7, it is considered that the particles of the ferromagnetic metal layer are continuous and the film thickness of the ferromagnetic metal layer necessary for reducing the dispersion of the reversal magnetic field is increased.

以上の結果から、グラニュラー磁性層表面のＣｒの酸化物を減らして粒界幅を狭めた実施例７は、実施例８に比べて大幅に隣接トラック消去耐性が向上できることがわかった。つまり、グラニュラー層表面の粒界幅を表面側で狭める、強磁性金属層が成長初期段階からグラニュラー磁性層の結晶粒界を跨ぐ形で連続的に成長した構造を有することがより好ましいことがわかった。 From the above results, it was found that Example 7 in which the grain boundary width was narrowed by reducing the Cr oxide on the surface of the granular magnetic layer could significantly improve the adjacent track erasure resistance compared to Example 8. That is, it is more preferable that the ferromagnetic metal layer has a structure in which the grain boundary width on the surface of the granular layer is narrowed on the surface side and the ferromagnetic metal layer is continuously grown from the initial stage of growth to straddle the grain boundary of the granular magnetic layer. It was.

［実施例９］
本発明による磁気記憶装置の模式図を図８に示す。図８（ａ）は平面模式図、図８（ｂ）は断面模式図である。磁気記録媒体１０は上記実施例１〜７の垂直磁気記録媒体で構成され、磁気記憶装置は、この磁気記録媒体を駆動する媒体駆動部１１、記録部と再生部を備える磁気ヘッド１２、磁気ヘッドを磁気記録媒体に対して相対運動させるアクチュエータ１３、磁気ヘッドへの信号の入出力を行うための信号処理系１４を有する。 [Example 9]
A schematic diagram of a magnetic storage device according to the present invention is shown in FIG. FIG. 8A is a schematic plan view, and FIG. 8B is a schematic cross-sectional view. The magnetic recording medium 10 is composed of the perpendicular magnetic recording media of the first to seventh embodiments, and the magnetic storage device includes a medium driving unit 11 that drives the magnetic recording medium, a magnetic head 12 that includes a recording unit and a reproducing unit, and a magnetic head. Has a signal processing system 14 for inputting / outputting signals to / from the magnetic head.

磁気ヘッド１２と磁気記録媒体１０の関係を図９に示す。磁気ヘッド１２の磁気的な浮上量を４ｎｍとし、再生部２０の再生素子２１にはトンネル磁気抵抗効果素子（ＴＭＲ）を使用し、シールドギャップ長５０ｎｍ、トラック幅５０ｎｍである。記録部２２の主磁極２３の周りにはラップアラウンドシールド２４が形成され、主磁極先端部の幾何学的なトラック幅は８０ｎｍ、主磁極−トレーリングシールド間の距離は５０ｎｍ、主磁極−サイドシールド間距離は８０ｎｍとした。主磁極２３、垂直磁気記録媒体１０の軟磁性下地層、補助磁極２５は磁気回路を構成し、その磁気回路に鎖交する薄膜導体コイル２６に通電することによって主磁極２３から発生された記録磁束は、垂直磁気記録媒体１０の磁性層及び軟磁性下地層を通って補助磁極２５に戻る。 The relationship between the magnetic head 12 and the magnetic recording medium 10 is shown in FIG. The magnetic flying height of the magnetic head 12 is 4 nm, a tunnel magnetoresistive effect element (TMR) is used for the reproducing element 21 of the reproducing unit 20, the shield gap length is 50 nm, and the track width is 50 nm. A wraparound shield 24 is formed around the main magnetic pole 23 of the recording unit 22, the geometric track width of the main magnetic pole tip is 80 nm, the distance between the main magnetic pole and the trailing shield is 50 nm, and the main magnetic pole-side shield. The inter-distance was 80 nm. The main magnetic pole 23, the soft magnetic underlayer of the perpendicular magnetic recording medium 10 and the auxiliary magnetic pole 25 constitute a magnetic circuit, and a recording magnetic flux generated from the main magnetic pole 23 by energizing a thin film conductor coil 26 linked to the magnetic circuit. Returns to the auxiliary magnetic pole 25 through the magnetic layer and the soft magnetic underlayer of the perpendicular magnetic recording medium 10.

本発明の媒体を用いることにより、１ｃｍあたりのトラック密度を８６６１４トラック、１ｃｍあたりの線記録密度を４７２４４１ビットとすることによって、１平方センチあたり４０．９ギガビットでの動作を確認でき、隣接トラック消去も実用上問題のないレベル（１以下）を確保できた。また、実施例１の媒体との組み合わせにおいて、１ｃｍあたりのトラック密度を８７７９５トラック、１ｃｍあたりの線記録密度を５３１４９６ビットとすることによって、１平方センチあたり４６．７ギガビットでの動作を確認でき、隣接トラック消去も実用上問題のないレベルを確保できた。 By using the medium of the present invention, the track density per cm is 86614 tracks, the linear recording density per cm is 472441 bits, and operation at 40.9 gigabits per square centimeter can be confirmed, and adjacent track erase Was able to secure a level (1 or less) with no practical problem. Further, in the combination with the medium of Example 1, by setting the track density per cm to 87795 tracks and the linear recording density per cm to 531496 bits, operation at 46.7 gigabits per square centimeter can be confirmed, Adjacent track erasure was also able to secure a level with no practical problems.

磁気ヘッドの再生素子２１としては、トンネル磁気抵抗効果素子の他に巨大磁気抵抗効果素子や、素子膜面垂直方向に電流を流す巨大磁気抵抗効果素子（ＣＰＰ−ＧＭＲ）を用いることもできる。また、記録ヘッドとしては、トラック幅方向のシールドのないシールドヘッドや単磁極ヘッドを用いることができる。ただし、記録磁界勾配を向上できる点で、少なくとも主磁極のダウントラック方向にシールドを設けたシールドヘッドが好ましい。 As the reproducing element 21 of the magnetic head, in addition to the tunnel magnetoresistive effect element, a giant magnetoresistive effect element or a giant magnetoresistive effect element (CPP-GMR) that allows current to flow in the direction perpendicular to the element film surface can also be used. As the recording head, a shield head without a shield in the track width direction or a single pole head can be used. However, a shield head in which a shield is provided at least in the down-track direction of the main pole is preferable in that the recording magnetic field gradient can be improved.

強磁性粒子に隣接する強磁性粒子の面積重心を結んだ線によって囲まれる領域に含まれる面積A_g+b、そこに含まれる粒界の面積A_bを表す模式図。The schematic diagram showing area A_g + b contained in the area | region enclosed by the line which tied the area gravity center of the ferromagnetic particle adjacent to a ferromagnetic particle, and the area A_b of the grain boundary contained there. 本発明による垂直磁気記録媒体の一例の断面模式図。1 is a schematic cross-sectional view of an example of a perpendicular magnetic recording medium according to the present invention. 規格化粒界面積A_b／A_g+bの分散とＳ／Ｎの関係を示す図。The figure which shows the dispersion | distribution of normalized grain interface area A_b / A_g + b, and S / N. 実施例１のサンプルのグラニュラー磁性層の微細構造の模式図。3 is a schematic diagram of a fine structure of a granular magnetic layer of a sample of Example 1. FIG. 比較例２のサンプルのグラニュラー磁性層の微細構造の模式図。The schematic diagram of the fine structure of the granular magnetic layer of the sample of the comparative example 2. FIG. 実施例７のＲｕ下地層、グラニュラー磁性層、強磁性金属層の断面構造を透過電子顕微鏡で観察した時の観察像を模式的に表した図。The figure which represented typically the observation image when the cross-section of the Ru base layer of Example 7, a granular magnetic layer, and a ferromagnetic metal layer was observed with the transmission electron microscope. 実施例８のＲｕ下地層、グラニュラー磁性層、強磁性金属層の断面構造を透過電子顕微鏡で観察した時の観察像を模式的に表した図。The figure which represented typically the observation image when the cross-section of the Ru base layer of Example 8, a granular magnetic layer, and a ferromagnetic metal layer was observed with the transmission electron microscope. 磁気記憶装置の断面模式図。1 is a schematic cross-sectional view of a magnetic storage device. 磁気ヘッドと磁気記録媒体の関係を示す模式図。FIG. 3 is a schematic diagram showing a relationship between a magnetic head and a magnetic recording medium.

符号の説明Explanation of symbols

１０：垂直磁気記録媒体、１１：媒体駆動部、１２：磁気ヘッド、１３：アクチュエータ、１４：信号処理系、１5：回路基板、２０：再生部、２１：再生素子、２２：記録部、２３：主磁極、２４：ラップアラウンドシールド、２５：補助磁極、２６：薄膜導体コイル、４１：基板、４２：密着層、４３：軟磁性下地層、４４：配向制御偏析促進層、４５：グラニュラー磁性層、４６：強磁性金属層、４７：保護層 10: perpendicular magnetic recording medium, 11: medium driving unit, 12: magnetic head, 13: actuator, 14: signal processing system, 15: circuit board, 20: reproducing unit, 21: reproducing element, 22: recording unit, 23: Main magnetic pole, 24: wraparound shield, 25: auxiliary magnetic pole, 26: thin film conductor coil, 41: substrate, 42: adhesion layer, 43: soft magnetic underlayer, 44: orientation control segregation promoting layer, 45: granular magnetic layer, 46: Ferromagnetic metal layer, 47: Protective layer

Claims

基板上に設けられた下地層と、ＣｏとＣｒとＰｔを主体とする強磁性結晶粒子及びそれを取り巻く非磁性粒界を有するグラニュラー磁性層と、前記グラニュラー磁性層の上に形成された酸化物を含まない強磁性金属層とを有し、
前記グラニュラー磁性層の前記強磁性結晶粒は（０００１）が優先配向した六方細密構造を有し、
前記グラニュラー磁性層のある強磁性結晶粒子に隣接する強磁性結晶粒子の面積重心を結んだ線によって囲まれる領域に含まれる面積をA_g+b、そこに含まれる粒界の面積をA_bとする時、前記グラニュラー磁性層中の規格化粒界面積A_b／A_g+bの分散が３０％以下であることを特徴とする垂直磁気記録媒体。 An underlayer provided on a substrate, a granular magnetic layer having ferromagnetic crystal grains mainly composed of Co, Cr, and Pt and a nonmagnetic grain boundary surrounding the ferromagnetic crystal grains, and an oxide formed on the granular magnetic layer And a ferromagnetic metal layer not containing
The ferromagnetic crystal grains of the granular magnetic layer have a hexagonal close-packed structure in which (0001) is preferentially oriented,
When the area included in the region surrounded by the line connecting the center of gravity of the ferromagnetic crystal particle adjacent to the ferromagnetic crystal particle having the granular magnetic layer is A_g + b, and the area of the grain boundary included therein is A_b The perpendicular magnetic recording medium is characterized in that the dispersion of the normalized grain interface area A_b / A_g + b in the granular magnetic layer is 30% or less.

請求項１に記載の垂直磁気記録媒体において、平均粒界幅が０．５ｎｍ以上１ｎｍ以下であることを特徴とする垂直磁気記録媒体。 2. The perpendicular magnetic recording medium according to claim 1, wherein an average grain boundary width is not less than 0.5 nm and not more than 1 nm.

請求項１に記載の垂直磁気記録媒体において、前記強磁性金属層が少なくともＣｏとＣｒを含むことを特徴とする垂直磁気記録媒体。 2. The perpendicular magnetic recording medium according to claim 1, wherein the ferromagnetic metal layer contains at least Co and Cr.

請求項１に記載の垂直磁気記録媒体において、前記強磁性金属層の結晶粒子が成長初期段階から、前記グラニュラー磁性層の結晶粒界を跨ぐ形で連続的に成長した構造を有することを特徴とする垂直磁気記録媒体。 2. The perpendicular magnetic recording medium according to claim 1, wherein the ferromagnetic metal layer has a structure in which crystal grains of the ferromagnetic metal layer are continuously grown from the initial growth stage so as to straddle the crystal grain boundaries of the granular magnetic layer. Perpendicular magnetic recording medium.

請求項１に記載の垂直磁気記録媒体において、前記磁性層の粒界幅は、前記下地層側の界面から中央付近までの平均粒界幅に比べて前記強磁性金属層側２ｎｍの領域の平均粒界幅が狭いことを特徴とする垂直磁気記録媒体。 2. The perpendicular magnetic recording medium according to claim 1, wherein a grain boundary width of the magnetic layer is an average of a region of 2 nm on the ferromagnetic metal layer side compared to an average grain boundary width from the interface on the underlayer side to the vicinity of the center. A perpendicular magnetic recording medium having a narrow grain boundary width.

請求項５に記載の垂直磁気記録媒体において、前記磁性層の粒界幅は、前記下地層側の界面から中央付近までの平均粒界幅に比べて前記強磁性金属層側２ｎｍの領域の平均粒界幅が狭くその差が０．３ｎｍ以上であることを特徴とする垂直磁気記録媒体。 6. The perpendicular magnetic recording medium according to claim 5, wherein the grain boundary width of the magnetic layer is an average of a region of 2 nm on the ferromagnetic metal layer side compared to an average grain boundary width from the interface on the underlayer side to the vicinity of the center. A perpendicular magnetic recording medium having a narrow grain boundary width and a difference of 0.3 nm or more.

磁気記録媒体と、前記磁気記録媒体を記録方向に駆動する手段と、記録部と再生部を備える磁気ヘッドと、前記磁気ヘッドを前記磁気記録媒体に対して相対的に駆動する手段と、前記磁気ヘッドに対する入力信号及び出力信号を処理する信号処理手段とを有する磁気記憶装置において、
前記磁気記録媒体は、基板上に設けられた下地層と、ＣｏとＣｒとＰｔを主体とする強磁性結晶粒子及びそれを取り巻く非磁性粒界を有するグラニュラー磁性層と、前記グラニュラー磁性層の上に形成された酸化物を含まない強磁性金属層とを有し、前記グラニュラー磁性層の前記強磁性結晶粒は（０００１）が優先配向した六方細密構造を有し、前記グラニュラー磁性層のある強磁性結晶粒子に隣接する強磁性結晶粒子の面積重心を結んだ線によって囲まれる領域に含まれる面積をA_g+b、そこに含まれる粒界の面積をA_bとする時、前記グラニュラー磁性層中の規格化粒界面積A_b／A_g+bの分散が３０％以下であることを特徴とする磁気記憶装置。 A magnetic recording medium; means for driving the magnetic recording medium in a recording direction; a magnetic head comprising a recording section and a reproducing section; means for driving the magnetic head relative to the magnetic recording medium; In a magnetic storage device having signal processing means for processing an input signal and an output signal to the head,
The magnetic recording medium includes an underlayer provided on a substrate, a granular magnetic layer having ferromagnetic crystal grains mainly composed of Co, Cr, and Pt and a nonmagnetic grain boundary surrounding the ferromagnetic crystal grains, and an upper surface of the granular magnetic layer. A ferromagnetic metal layer that does not contain an oxide, and the ferromagnetic crystal grains of the granular magnetic layer have a hexagonal close-packed structure in which (0001) is preferentially oriented. When the area included in the region surrounded by the line connecting the center of gravity of the ferromagnetic crystal particle adjacent to the magnetic crystal particle is A_g + b and the area of the grain boundary included therein is A_b, the granular magnetic layer A magnetic storage device, wherein the dispersion of the normalized grain interface area A_b / A_g + b is 30% or less.