JP4639477B2 - Method for manufacturing magnetic recording medium - Google Patents

Method for manufacturing magnetic recording medium Download PDF

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Publication number
JP4639477B2
JP4639477B2 JP2001016256A JP2001016256A JP4639477B2 JP 4639477 B2 JP4639477 B2 JP 4639477B2 JP 2001016256 A JP2001016256 A JP 2001016256A JP 2001016256 A JP2001016256 A JP 2001016256A JP 4639477 B2 JP4639477 B2 JP 4639477B2
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Prior art keywords
film
recording medium
magnetic recording
carbon
wall
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JP2002222511A (en
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和大 草川
真樹 宮里
眞紀 吉原
秀樹 松尾
正雄 窪田
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Fuji Electric Co Ltd
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Fuji Electric Device Technology Co Ltd
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Description

【0001】
【発明の属する技術分野】
本発明は、現在、コンピュータの外部記録装置として主に用いられているハードディスクドライブ(HDD)に用いられる磁性膜を具えた磁気記録媒体およぼびその製造方法に関する。詳しくは、記録層を形成する磁性膜をヘッドの衝撃、外界の腐食性物質などの腐食から保護する機能を有するカーボン保護膜を有する磁気記録媒体およびその製造方法に関する。さらに詳しくは、カーボン保護膜の成膜時に該保護膜に生じるパーティクルを減少させて高信頼性を実現した磁気記録媒体およびその製造方法に関する。
【0002】
【従来の技術】
現在、HDDに用いられる磁気記録媒体の面記録密度は、開発段階で20Gbits/inまで達し、年率100%で向上している。このような磁気記録のより一層の高密度化により、さらに小さな磁化領域を高いSN比で読み出すためには、書き込み/読み出しヘッドを記録媒体表面にさらに近づけることが要求されるようになった。現在、ヘッド浮上量は、20Gbits/inで、19nm以下、50Gbits/inでは、15nm以下と見積もられている。そして、今後も、磁気記録の高密度化に対応して、磁気記録媒体とデータR/W用ヘッドとの浮上間隔を狭くすることが求められると、予想される。したがって、磁気記録媒体表面の保護膜に関しても、当然、薄膜化が必要となる。
【0003】
このような保護膜は、従来、スパッタ法により成膜されている。スパッタ法によれば、周知のように、耐久性および耐食性を有する保護膜を成膜することができるが、膜厚を80Å以下にすることは困難である。そこで、スパッタ法に代わる次世代カーボン保護膜の成膜プロセスとして、より高密度な膜が得られるというプラズマCVD法が注目され、活発に研究が行われている。
【0004】
しかしながら、CVD法により成膜を開始すると、装置稼動初期に成膜用チャンバー内壁に避けがたくカーボン膜が形成され、このカーボン膜が壁面から剥離、落下し、パーティクルとなって記録媒体上に付着する。この時のパーティクルの数は非常に多くて、製造した磁気記録媒体には良品が得られない。そのまま運転を続けると、壁面に付着していたカーボン膜が剥離により消費されて、記録媒体表面に付着するパーティクル数は徐々に減少するが、磁気記録媒体にとって実用上問題にならない目標数に低減するまでには、時間がかかり、歩留まりの低下を招いてしまう。
【0005】
これに対して、従来、成膜チャンバーの内壁表面をケイ素と酸素を含有する物質または炭素を含有する物質にて構成する方法が提案されている(特開平11−189876号公報)。前記炭素を含有する物質としては、具体的にグラファイト、アモルファスカーボン、ポリエチレン等が挙げられているが、このような炭素を含有する物質によって、チャンバー内壁に形成した膜の特性と、磁気記録媒体表面に付着するパーティクルの付着数およびパーティクルサイズとの関係は、開示も示唆もされていない。この先行技術文献には、チャンバー内壁にカーボンを含有する物質により膜を形成した後に、このチャンバーを用いて磁気記録媒体を形成した場合のパーティクル付着数が一面あたり約200個との開示があるが、パーティクルサイズの開示は全くない。磁気記録媒体におけるグライド特性の向上には、パーティクル付着数とパーティクルサイズの両方をコントロールする必要がある。そのためには、パーティクル付着数とパーティクルサイズの許容限度を知ることが重要である。そして、これらの許容限度と、チャンバー内壁に形成する膜の特性との間の相関を、知る必要がある。これらを知ることによって、初めて、磁気記録媒体表面に避けがたく付着するパーティクルを実用上問題のない範囲に抑制する制御システムの再現性および信頼性を、確保することができる。しかしながら、この先行技術文献には、係る開示が全くない。
【0006】
【発明が解決しようとする課題】
そこで、本発明の課題は、磁気記録媒体の製造において、装置稼動初期に成膜用チャンバーの内壁から発生するパーティクルの増加を低減し、目標数までの低減にかかる時間を短くする方法を提供し、磁気記録媒体製造の歩留まりを上げるとともに、製造される磁気記録媒体の品質を向上させることにある。さらに詳しくは、パーティクル付着数とパーティクルサイズの許容限度を確定するとともに、これらの許容限度とチャンバー内壁に形成する膜の特性との間の相関を求め、それによって、磁気記録媒体表面に避けがたく付着するパーティクルを実用上問題のない範囲に抑制することのできる磁気記録媒体の製造方法と、該方法により得られる高品質な磁気記録媒体とを提供することが、本発明の課題である。
【0007】
【課題を解決するための手段】
本発明者らは、このような課題を解決するために、鋭意、実験、検討を重ねたところ、下記のような知見を得るに至った。磁性層上にカーボン保護膜の本成膜を行う前に、成膜用チャンバー内壁に応力の小さいカーボン膜を成膜すること、そしてカーボン膜を剥離しにくくすれば装置可動初期のパーティクルの増加を低減できることを見いだした。さらに詳しくは、前記磁性層上に、カーボン保護膜を本成膜する前に、成膜用チャンバーの内壁に圧縮応力が1.0〜2.5GPaであるカーボン膜を成膜すると、磁気記録媒体の保護膜に付着するパーティクルのうち0.3μm以上の大きさのパーティクルの存在量を100個/3.5インチ基板以下に減少させることができる。これによって、高品質な磁気記録密度を有する磁気記録媒体を高い歩留まりにより製造することができることを、見いだすに至った。
【0009】
発明に係る磁気記録媒体の製造方法は、非磁性基板上に少なくとも磁性層、カーボン保護膜、および液体潤滑剤を順次積層する磁気記録媒体の製造方法において、前記磁性層上に前記カーボン保護膜を本成膜する前に、成膜用チャンバーの内壁に圧縮応力が1.0〜2.5GPaのカーボン膜を成膜して、前記カーボン保護膜の本成膜時に前記成膜用チャンバー内壁からのカーボン膜の剥離を防止し、前記保護膜の表面に付着するパーティクルを減らすことを特徴とする。
【0010】
前述の構成を有する本発明において、さらに好ましくは、前記カーボン膜の圧縮応力を1.5〜2.0GPaとする。
【0011】
また、前記カーボン膜の前記チャンバー内壁への成膜厚さは、3.0〜5.0μmとすることが、好ましく、より好ましくは、前記カーボン膜の成膜厚さを3.5〜4.0μmとする。
【0012】
【発明の実施の形態】
本発明の磁気記録媒体は、非磁性基板上に順次積層された磁性層、カーボン保護膜、および液体潤滑層を、少なくとも有する。
【0013】
本発明で使用される非磁性基板は、アルミ合金、ガラス、プラスチック基板など、慣用のいかなる非磁性基板でもよい。具体的なプラスチック基板としては、ポリカーボネート、ポリオレフィン、ポリエチレンテレフタレート、ポリエチレンナフタレート、ポリイミドなどから成る基板を挙げることができる。
【0014】
基板は、2.5インチ、3インチ、3.3インチ、3.5インチ、5インチ、のいずれの大きさのディスク基板であってもよく、またその形態も、ディスク状に限られず、カード状、帯状などいかなる形態でもよい。なお、ここで示した大きさは公称値であり、当該技術において汎用されているものであると理解されるべきである。
【0015】
本発明で使用される磁性膜は、記録層として使用できる強磁性金属を含み、具体的には、CoCrTaPt,CoCrTaPt−Cr,CoCrTaPt−SiO,CoCrTaPt−ZrO,CoCrTaPt−TiO,CoCrTaPt−Alなどを成分とする磁性膜である。
【0016】
磁性層の厚さは、20nm以下であり、好ましくは10〜20nmである。磁性膜を複数用いて多層構造の記録層としてもよい。
【0017】
また、磁性層と基板の間に下地層を形成してもよい。下地層は、下地層を形成する慣用のいかなる成分から形成されてもよく、特に限定されない。具体的には、Cr,Cr−W,Cr−V,Cr−Mo,Cr−Si,Ni−Al,CoCr,Mo,W,Ptなどから成る。
【0018】
下地層の厚さは、20nm以下であり、好ましくは10〜20nmである。
【0019】
潤滑剤は、液体潤滑剤でパーフルオロ−ポリエーテルが使用され、その中でもZ−dol(商品名、アウジモント社製)が望ましい。
【0020】
保護膜は、記録層を形成する磁性膜をヘッドの衝撃、外界の腐食性物質などの腐食から保護する機能を有する。保護膜の厚さは8nm以下であり、好ましくは3〜8nmである。
【0021】
保護膜は、DLC(Diamond−like Carbon)をプラズマCVD法により成膜して得ることができる。プラズマCVD法とは、原料となるガスを、熱エネルギーではなく、電磁気的なエネルギーを加えて電子によって分解し、低温で薄膜を形成する方法である。具体的には、気相成長によって成膜成長を行うCVDに放電を行わせる装置を組み合わせた装置を用いて薄膜を形成することができる。プラズマCVD法としては、フィラメント方式イオンビーム−CVD、ホローカソード方式イオンビーム−CVD、電子サイクロトロン共鳴−CVD、高周波−CVD、電子ビーム励起プラズマ−CVDなどを挙げることができ、いずれの方法で成膜してもよい。
【0022】
DLCを成膜する際の原料ガスは、炭化水素系ガス、例えば、メタン(CH)、エチレン(C),アセチレン(C),トルエン(C)などを用いる。
【0023】
チャンバー内壁と同電位である基板に成膜されたカーボン膜の応力について検討した結果、チャンバー内壁に成膜されたカーボン膜が一定の応力を有する場合に、0.3μm以上の大きさのパーティクルが100個/3.5インチ基板以下となることが見出された。
【0024】
応力は、基板反り変形法により求めた。膜に存在する残留応力のために生じた基板自身の反り変形量から、膜に発生している平均的な残留応力を求めた。
【0025】
図1に示すように、本発明でチャンバー内壁に成膜されたカーボン膜は、応力が1.0〜2.5GPaであり、好ましくは1.5〜2.0GPaである。応力が2.5GPaより大きいとチャンバー内壁から剥離しやすくパーティクルの元となり、一方、1.0GPaより小さいと応力の大きい本成膜カーボンとの応力差が大きく密着性が悪くなってしまい、本成膜カーボンがチャンバー内壁から剥離しやすくパーティクルの元となってしまう。
【0026】
1.0GPaの応力を有するカーボン膜は、本成膜時のイオンの加速度に関わるパラメータであるアノード−グランド間の電圧の1/4の電圧で成膜でき、2.5GPaの応力を有するカーボン膜は、5/8の電圧で成膜できる。
【0027】
また、本成膜前に、チャンバー内壁に成膜するカーボン膜の厚さは、3.0〜5.0μmであり、好ましくは3.5〜4.0μmである。膜厚が3.0μmより薄いと、薄すぎてチャンバー内壁と本成膜カーボンとの緩衝効果が得られない。一方、膜厚が5.0μmより大きいと、成膜する時間が長すぎて、装置の稼動率が低くなってしまう。
【0028】
なお、保護膜表面のパーティクル数測定には、光学式外観試験機を使用した。
【0029】
【実施例】
以下に、実施例を挙げて本発明を説明するが、本発明は以下の実施例にのみ限定されるものではない。
【0030】
(実施例1)
図2は、本実施例の磁気記録媒体1の概略断面図である。図2に示すように、アルミ合金基板(非磁性基板)2上に、NiPメッキ(メッキ層)3を施し、その上にスパッタ法で20nmのCr下地層4および20nmのCo磁性層5を成膜した。さらにその上に、以下に詳細に説明するホローカソード方式イオンビーム−CVDにより、エチレン(C)を原料に用いてDLC保護膜6を成膜した。
【0031】
図3は、ホローカソード−CVDの原理図である。装置は、ホローカソード110、アノード電極111、マグネット112で構成され、ホローカソード110より発生した熱電子はアノード電圧によりアノード側に引き付けられ、アノード側から導入されたArガスと衝突し、Arを発生させ、アノード電圧により押し出されたArはCと衝突し、プラズマを発生させる。マグネット112はプラズマ密度を制御する。プラズマ中のイオンはアノード電圧で基板113側へ押し出される。
【0032】
本成膜の前、チャンバー内壁に、応力2.0GPaのカーボン膜を3.5μm成膜した後に、本成膜を行った。
【0033】
次に、保護膜表面に、Z−dol(商品名、アウジモント社製)を塗布して2nmの液体潤滑層を形成した。
【0034】
得られた磁気記録媒体を用いて信頼性試験をしたところ、3.5インチ基板で0.3μm以上の大きさのパーティクル数が60個/面程度のものが多く、良品率も約80%であった。
【0035】
(比較例1)
本比較例では、本成膜前に、チャンバー内壁に応力の小さいカーボン膜の成膜を行わず、本成膜を行った。
【0036】
次に、保護膜表面に、Z−dol(商品名、アウジモント社製)を塗布して2nmの液体潤滑層を形成した。
【0037】
得られた磁気記録媒体を用いて信頼性試験をしたところ、3.5インチ基板で0.3μm以上の大きさのパーティクル数が1000個/面と非常に多く、良品率0%であった。
【0038】
【発明の効果】
本発明によると、カーボン保護膜の本成膜前に、チャンバー内壁に応力の小さいカーボン膜を成膜しておくことにより、本成膜後にチャンバー内壁からのカーボン膜を剥離しにくくし、磁気記録媒体への付着をなくすことで、保護膜表面のパーティクルを少なくすることができ、高良品率とすることができる。したがって、本発明は、磁気記録のより一層の高密度化に十分に対応できる高信頼性の磁気記録媒体を提供することができる。
【図面の簡単な説明】
【図1】チャンバー内壁に成膜したカーボン膜の応力と装置稼動直後のパーティクル数との関係を示した図である。
【図2】本発明の磁気記録媒体の一実施例を示す媒体の断面概略図である。
【図3】ホローカソード方式イオンビーム−CVD装置の概略構成図である。
【符号の説明】
1 磁気記録媒体
2 非磁性基板
3 めつき層
4 下地層
5 磁性層
6 DLC保護膜
110 ホローカソード
111 アノード電極
112 マグネット
113 基板
114 電源
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic recording medium including a magnetic film used in a hard disk drive (HDD) mainly used as an external recording device of a computer at present, and a manufacturing method thereof. More specifically, the present invention relates to a magnetic recording medium having a carbon protective film having a function of protecting a magnetic film forming a recording layer from head impact and corrosion of an external corrosive substance and a manufacturing method thereof. More specifically, the present invention relates to a magnetic recording medium that realizes high reliability by reducing particles generated in the protective film when the carbon protective film is formed, and a manufacturing method thereof.
[0002]
[Prior art]
Currently, the surface recording density of magnetic recording media used in HDDs reaches 20 Gbits / in 2 at the development stage, and is improving at an annual rate of 100%. Due to the further increase in the density of magnetic recording, it has become necessary to bring the write / read head closer to the surface of the recording medium in order to read a smaller magnetization region with a high SN ratio. Currently, the head flying height, at 20 Gbits / in 2, 19 nm or less, the 50Gbits / in 2, it is estimated to 15nm or less. In the future, it is expected that it will be required to reduce the flying distance between the magnetic recording medium and the data R / W head in response to the higher density of magnetic recording. Therefore, it is naturally necessary to reduce the thickness of the protective film on the surface of the magnetic recording medium.
[0003]
Such a protective film is conventionally formed by sputtering. According to the sputtering method, as is well known, a protective film having durability and corrosion resistance can be formed, but it is difficult to reduce the film thickness to 80 mm or less. Therefore, as a process for forming a next-generation carbon protective film in place of the sputtering method, a plasma CVD method capable of obtaining a higher-density film has attracted attention and has been actively researched.
[0004]
However, when film formation is started by the CVD method, a carbon film is unavoidably formed on the inner wall of the film formation chamber in the initial stage of operation of the apparatus, and this carbon film peels off from the wall surface, falls, and adheres to the recording medium as particles. To do. At this time, the number of particles is very large, and a manufactured magnetic recording medium cannot be obtained. If the operation is continued as it is, the carbon film adhering to the wall surface will be consumed by peeling, and the number of particles adhering to the surface of the recording medium will gradually decrease, but it will be reduced to a target number that does not cause any practical problems for the magnetic recording medium. This takes time and leads to a decrease in yield.
[0005]
On the other hand, conventionally, a method has been proposed in which the inner wall surface of the film forming chamber is made of a substance containing silicon and oxygen or a substance containing carbon (Japanese Patent Laid-Open No. 11-189876). Specific examples of the carbon-containing substance include graphite, amorphous carbon, polyethylene, and the like. The characteristics of the film formed on the inner wall of the chamber by such a substance containing carbon, and the surface of the magnetic recording medium The relationship between the number of particles adhering to the particle and the particle size is not disclosed or suggested. This prior art document discloses that the number of adhered particles is about 200 per side when a magnetic recording medium is formed using a chamber containing a film containing carbon on the inner wall of the chamber. There is no disclosure of particle size. In order to improve the glide characteristics in a magnetic recording medium, it is necessary to control both the number of particles attached and the particle size. For that purpose, it is important to know the number of adhering particles and the allowable limit of the particle size. It is necessary to know the correlation between these allowable limits and the characteristics of the film formed on the inner wall of the chamber. For the first time, it is possible to ensure the reproducibility and reliability of the control system that suppresses particles that inevitably adhere to the surface of the magnetic recording medium to a practically unproblematic range by knowing these matters. However, this prior art document has no disclosure.
[0006]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a method for reducing the increase in particles generated from the inner wall of the film formation chamber in the initial stage of operation of the apparatus and reducing the time required for the reduction to the target number in the manufacture of the magnetic recording medium. An object of the present invention is to increase the yield of manufacturing the magnetic recording medium and improve the quality of the manufactured magnetic recording medium. More specifically, the allowable number of particle adhesion and particle size are determined, and a correlation between the allowable limit and the characteristics of the film formed on the inner wall of the chamber is obtained, thereby making it difficult to avoid the surface of the magnetic recording medium. It is an object of the present invention to provide a method for producing a magnetic recording medium capable of suppressing adhering particles to a practically no problem range, and a high-quality magnetic recording medium obtained by the method.
[0007]
[Means for Solving the Problems]
In order to solve such problems, the present inventors have intensively conducted experiments and examinations, and have obtained the following knowledge. Before the main film formation of the carbon protective film on the magnetic layer, a carbon film with low stress is formed on the inner wall of the film formation chamber, and if the carbon film is difficult to peel off, the number of particles at the initial stage of moving the device can be increased. I found that it can be reduced. More specifically, when a carbon film having a compressive stress of 1.0 to 2.5 GPa is formed on the inner wall of the film forming chamber before the main formation of the carbon protective film on the magnetic layer , the magnetic recording medium The amount of particles having a size of 0.3 μm or more among the particles adhering to the protective film can be reduced to 100 / 3.5 inch substrate or less. As a result, it has been found that a magnetic recording medium having a high quality magnetic recording density can be produced with a high yield.
[0009]
The method of manufacturing a magnetic recording medium according to the present invention includes a method of manufacturing a magnetic recording medium in which at least a magnetic layer, a carbon protective film, and a liquid lubricant are sequentially laminated on a nonmagnetic substrate. Before the main film formation, a carbon film having a compressive stress of 1.0 to 2.5 GPa is formed on the inner wall of the film formation chamber, and from the inner wall of the film formation chamber during the main film formation of the carbon protective film. The carbon film is prevented from peeling off, and particles adhering to the surface of the protective film are reduced.
[0010]
In the present invention having the above-described configuration, more preferably, the compressive stress of the carbon film is 1.5 to 2.0 GPa.
[0011]
The film thickness of the carbon film on the inner wall of the chamber is preferably 3.0 to 5.0 μm, and more preferably the film thickness of the carbon film is 3.5 to 4. 0 μm.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The magnetic recording medium of the present invention has at least a magnetic layer, a carbon protective film, and a liquid lubricating layer that are sequentially laminated on a nonmagnetic substrate.
[0013]
The nonmagnetic substrate used in the present invention may be any conventional nonmagnetic substrate such as an aluminum alloy, glass, or plastic substrate. Specific examples of the plastic substrate include substrates made of polycarbonate, polyolefin, polyethylene terephthalate, polyethylene naphthalate, polyimide, and the like.
[0014]
The board may be a disk board of any size of 2.5 inch, 3 inch, 3.3 inch, 3.5 inch, 5 inch, and the form is not limited to the disk shape, and the card Any shape such as a shape or a belt shape may be used. In addition, it should be understood that the size shown here is a nominal value and is widely used in the art.
[0015]
The magnetic film used in the present invention includes a ferromagnetic metal that can be used as a recording layer. Specifically, CoCrTaPt, CoCrTaPt—Cr 2 O 3 , CoCrTaPt—SiO 2 , CoCrTaPt—ZrO 2 , CoCrTaPt—TiO 2 , A magnetic film containing CoCrTaPt—Al 2 O 3 or the like as a component.
[0016]
The thickness of the magnetic layer is 20 nm or less, preferably 10 to 20 nm. A plurality of magnetic films may be used to form a multilayered recording layer.
[0017]
An underlayer may be formed between the magnetic layer and the substrate. The underlayer may be formed from any conventional component that forms the underlayer, and is not particularly limited. Specifically, it consists of Cr, Cr—W, Cr—V, Cr—Mo, Cr—Si, Ni—Al, CoCr, Mo, W, Pt, and the like.
[0018]
The thickness of the underlayer is 20 nm or less, preferably 10 to 20 nm.
[0019]
As the lubricant, perfluoro-polyether is used as a liquid lubricant, and among them, Z-dol (trade name, manufactured by Augmont) is desirable.
[0020]
The protective film has a function of protecting the magnetic film forming the recording layer from the impact of the head and the corrosion of corrosive substances in the outside world. The thickness of the protective film is 8 nm or less, preferably 3 to 8 nm.
[0021]
The protective film can be obtained by forming DLC (Diamond-like Carbon) by plasma CVD. The plasma CVD method is a method of forming a thin film at a low temperature by decomposing a gas as a raw material with electrons instead of heat energy and applying electromagnetic energy. Specifically, a thin film can be formed using an apparatus that combines a CVD apparatus that performs film growth by vapor deposition and an apparatus that discharges. Examples of the plasma CVD method include filament type ion beam-CVD, hollow cathode type ion beam-CVD, electron cyclotron resonance-CVD, high-frequency-CVD, and electron beam excitation plasma-CVD. May be.
[0022]
As a source gas for forming a DLC film, a hydrocarbon gas such as methane (CH 4 ), ethylene (C 2 H 4 ), acetylene (C 2 H 2 ), toluene (C 7 H 8 ), or the like is used. .
[0023]
As a result of examining the stress of the carbon film formed on the substrate having the same potential as the inner wall of the chamber, when the carbon film formed on the inner wall of the chamber has a certain stress, particles having a size of 0.3 μm or more are generated. It has been found that there are no more than 100 / 3.5 inch substrates.
[0024]
The stress was obtained by the substrate warpage deformation method. The average residual stress generated in the film was obtained from the amount of warpage deformation of the substrate itself caused by the residual stress existing in the film.
[0025]
As shown in FIG. 1, the carbon film formed on the inner wall of the chamber according to the present invention has a stress of 1.0 to 2.5 GPa, preferably 1.5 to 2.0 GPa. If the stress is greater than 2.5 GPa, it will be easy to peel off from the inner wall of the chamber, while if it is less than 1.0 GPa, the stress difference from the deposited carbon having a large stress will be large, resulting in poor adhesion. The film carbon easily peels off from the inner wall of the chamber and becomes a source of particles.
[0026]
The carbon film having a stress of 1.0 GPa can be formed at a voltage of 1/4 of the voltage between the anode and the ground, which is a parameter related to the acceleration of ions during the main film formation, and has a stress of 2.5 GPa. Can be formed at a voltage of 5/8.
[0027]
Moreover, the thickness of the carbon film formed on the inner wall of the chamber before the main film formation is 3.0 to 5.0 μm, preferably 3.5 to 4.0 μm. If the film thickness is less than 3.0 μm, the buffering effect between the inner wall of the chamber and the film-forming carbon cannot be obtained because it is too thin. On the other hand, if the film thickness is larger than 5.0 μm, the film formation time is too long and the operation rate of the apparatus is lowered.
[0028]
An optical appearance tester was used for measuring the number of particles on the surface of the protective film.
[0029]
【Example】
Hereinafter, the present invention will be described with reference to examples. However, the present invention is not limited to the following examples.
[0030]
Example 1
FIG. 2 is a schematic sectional view of the magnetic recording medium 1 of this embodiment. As shown in FIG. 2, a NiP plating (plating layer) 3 is applied on an aluminum alloy substrate (nonmagnetic substrate) 2, and a 20 nm Cr underlayer 4 and a 20 nm Co magnetic layer 5 are formed thereon by sputtering. Filmed. Furthermore, a DLC protective film 6 was formed using ethylene (C 2 H 4 ) as a raw material by hollow cathode type ion beam-CVD described in detail below.
[0031]
FIG. 3 is a principle diagram of hollow cathode-CVD. The apparatus includes a hollow cathode 110, an anode electrode 111, and a magnet 112. Thermoelectrons generated from the hollow cathode 110 are attracted to the anode side by the anode voltage, collide with Ar gas introduced from the anode side, and Ar + Ar + generated and pushed by the anode voltage collides with C 2 H 4 to generate plasma. The magnet 112 controls the plasma density. Ions in the plasma are pushed out to the substrate 113 side by an anode voltage.
[0032]
Before the main film formation, a carbon film having a stress of 2.0 GPa was formed on the inner wall of the chamber at a thickness of 3.5 μm, and then the main film formation was performed.
[0033]
Next, Z-dol (trade name, manufactured by Augmont) was applied to the surface of the protective film to form a 2 nm liquid lubricating layer.
[0034]
When a reliability test was performed using the obtained magnetic recording medium, the number of particles having a size of 0.3 μm or more on a 3.5-inch substrate was mostly about 60 particles / surface, and the yield rate was about 80%. there were.
[0035]
(Comparative Example 1)
In this comparative example, the main film was formed before the main film formation, without forming a carbon film having a low stress on the inner wall of the chamber.
[0036]
Next, Z-dol (trade name, manufactured by Augmont) was applied to the surface of the protective film to form a 2 nm liquid lubricating layer.
[0037]
When a reliability test was performed using the obtained magnetic recording medium, the number of particles having a size of 0.3 μm or more on a 3.5 inch substrate was as large as 1000 particles / surface, and the yield rate was 0%.
[0038]
【The invention's effect】
According to the present invention, a carbon film having a low stress is formed on the inner wall of the chamber before the main film formation of the carbon protective film, thereby making it difficult to peel off the carbon film from the inner wall of the chamber after the main film formation. By eliminating adhesion to the medium, particles on the surface of the protective film can be reduced, and a high yield rate can be achieved. Therefore, the present invention can provide a highly reliable magnetic recording medium that can sufficiently cope with higher density of magnetic recording.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between the stress of a carbon film formed on the inner wall of a chamber and the number of particles immediately after operation of the apparatus.
FIG. 2 is a schematic cross-sectional view of a medium showing an embodiment of the magnetic recording medium of the present invention.
FIG. 3 is a schematic configuration diagram of a hollow cathode type ion beam-CVD apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Magnetic recording medium 2 Nonmagnetic board | substrate 3 Mating layer 4 Underlayer 5 Magnetic layer 6 DLC protective film 110 Hollow cathode 111 Anode electrode 112 Magnet 113 Substrate 114 Power supply

Claims (4)

非磁性基板上に少なくとも磁性層、カーボン保護層、および液体潤滑剤を順次積層することによって磁気記録媒体を得る磁気記録媒体の製造方法において、
前記磁性層上にカーボン保護層を本成膜する前に、成膜チャンバー内壁に圧縮応力が1.0〜2.5GPaであるカーボン膜を成膜して、前記カーボン保護膜の本成膜時に前記成膜チャンバー内壁からのカーボン膜の剥離を防止し、前記保護膜の表面に付着するパーティクルを減らすことを特徴とする磁気記録媒体の製造方法。
In a method of manufacturing a magnetic recording medium, a magnetic recording medium is obtained by sequentially laminating at least a magnetic layer, a carbon protective layer, and a liquid lubricant on a nonmagnetic substrate.
Before the main film formation of the carbon protective layer on the magnetic layer, a carbon film having a compressive stress of 1.0 to 2.5 GPa is formed on the inner wall of the film formation chamber. A method of manufacturing a magnetic recording medium, wherein the carbon film is prevented from peeling from the inner wall of the film forming chamber and particles adhering to the surface of the protective film are reduced.
前記カーボン膜の圧縮応力を1.5〜2.0GPaとすることを特徴とする請求項1に記載の磁気記録媒体の製造方法。  2. The method of manufacturing a magnetic recording medium according to claim 1, wherein the compressive stress of the carbon film is 1.5 to 2.0 GPa. 前記カーボン膜の前記チャンバー内壁への成膜厚さを3.0〜5.0μmとすることを特徴とする請求項1または2に記載の磁気記録媒体の製造方法。  3. The method of manufacturing a magnetic recording medium according to claim 1, wherein a film thickness of the carbon film on the inner wall of the chamber is set to 3.0 to 5.0 μm. 前記カーボン膜の前記チャンバー内壁への成膜厚さを3.5〜4.0μmとすることを特徴とする請求項1ないし3のいずれか一項に記載の磁気記録媒体の製造方法。  4. The method of manufacturing a magnetic recording medium according to claim 1, wherein a thickness of the carbon film formed on the inner wall of the chamber is set to 3.5 to 4.0 μm.
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JPS63129628A (en) * 1986-11-20 1988-06-02 Matsushita Electric Ind Co Ltd Plasma cvd method
JPH11189876A (en) * 1997-12-24 1999-07-13 Mitsubishi Chemical Corp Film forming device and production of magnetic recording medium
JPH11229150A (en) * 1998-02-16 1999-08-24 Anelva Corp Film forming device for information recording disk
JP2000226661A (en) * 1999-02-02 2000-08-15 Mitsubishi Chemicals Corp Formation of film and production of magnetic recording medium
JP2000226670A (en) * 1999-02-02 2000-08-15 Mitsubishi Chemicals Corp Cvd device, and manufacture of magnetic recording medium
JP2000345343A (en) * 1999-06-03 2000-12-12 Tokyo Electron Ltd Film forming device

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JPS63129628A (en) * 1986-11-20 1988-06-02 Matsushita Electric Ind Co Ltd Plasma cvd method
JPH11189876A (en) * 1997-12-24 1999-07-13 Mitsubishi Chemical Corp Film forming device and production of magnetic recording medium
JPH11229150A (en) * 1998-02-16 1999-08-24 Anelva Corp Film forming device for information recording disk
JP2000226661A (en) * 1999-02-02 2000-08-15 Mitsubishi Chemicals Corp Formation of film and production of magnetic recording medium
JP2000226670A (en) * 1999-02-02 2000-08-15 Mitsubishi Chemicals Corp Cvd device, and manufacture of magnetic recording medium
JP2000345343A (en) * 1999-06-03 2000-12-12 Tokyo Electron Ltd Film forming device

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