JP3791774B2 - Substrate cleaning method, magnetic recording medium, and manufacturing method of magnetic recording medium - Google Patents
Substrate cleaning method, magnetic recording medium, and manufacturing method of magnetic recording medium Download PDFInfo
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Images
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- Cleaning In General (AREA)
- Cleaning By Liquid Or Steam (AREA)
- Surface Treatment Of Glass (AREA)
- Magnetic Record Carriers (AREA)
- Manufacturing Of Magnetic Record Carriers (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、基板洗浄方法、磁気記録媒体、及び、その製造方法に関し、より詳細には、テクスチャ加工されたガラス系基板又はセラミックス系基板の洗浄方法、及び、それを用いた磁気記録媒体、並びに、磁気記録媒体の製造方法に関する。
【０００２】
【従来の技術】
磁気記録媒体の高記録密度化が進むにつれて、磁気記録媒体に書き込まれるデータの最小単位である１ビットのサイズは小さくなってきている。ガラス系基板を用いた磁気記録媒体では等方性媒体が主流であるが、ビットサイズが小さくなるにつれて、アルミ系基板のような異方性媒体と比較してＲｅｓｏｌｕｔｉｏｎ（ＬＦ出力に対するＨＦ出力の割合）が低く、ＳＮＲ（信号に対する雑音の比）も悪いという特性差が顕著になってきた。これは、等方性媒体で異方性媒体と同様な特性を得るためには、円周方向のＭｒｔを高くする必要があるため、磁性層の厚さが厚くなり、結果として磁性膜に起因する媒体ノイズが増加してしまうためである。そこで、ガラス系基板上に、低コストで異方性媒体を作製する必要があり、例えば、ガラス系基板上に直接テクスチャ加工を施して、ガラス系基板の異方性媒体を作製するという磁気記録媒体の製造方法が提案されている。
【０００３】
一方、一般的な磁気記録媒体の製造工程においては、テクスチャ加工後の基板表面洗浄方法として、カップ式やロール式のスクラブ洗浄方法や、ディップ層などを使用した薬液や超音波による浸漬洗浄方法が採用されており、これにより、テクスチャ加工によって基板表面上に残存するダイア砥粒やスラリー液などの加工残渣を除去している。
【０００４】
【発明が解決しようとする課題】
しかしながら、ガラス系基板に直接テクスチャ加工を施して、ガラス系基板異方性媒体を作製する場合には、テクスチャ加工によって形成される溝は従来の媒体のテクスチャ溝よりも微細であるために、その溝中に残存するダイア砥粒やスラリー液などが従来の洗浄法では除去しきれず、磁気記録媒体にした場合にこれらの残存物に起因するＧＨ欠陥やエラー欠陥等の不具合が発生してしまい、製品価値が損なわれてしまうという問題があった。そのため、ガラス系基板を用いた異方性媒体の作製においては、テクスチャ加工後の基板洗浄レベルを向上することによって信頼性の高い磁気記録媒体を製造することが求められている。
【０００５】
本発明者らは、カップ式やロール式のスクラブ洗浄やディップ式洗浄といった従来の基板洗浄方法に用いられる洗剤種やスポンジ種等の検討を行ったが、何れの方法によっても基板表面上の異物除去レベルは不充分であった。また、ガラス系基板の洗浄に一般的に用いられているフッ酸を用いた浸漬洗浄法でフッ酸の濃度を高めて洗浄実験を実行したが、異物除去効果は僅かに向上するものの、フッ酸によるエッチングにより基板表面に荒れが発生してしまい製造方法としては実用的ではなかった。
【０００６】
本発明は、このような問題に鑑みてなされたものであって、その目的とするところは、表面に微細なテクスチャ加工を施した基板表面上に残存するダイア砥粒やスラリー等の残渣や微小突起を充分に除去することが可能な基板洗浄方法を提供すること、及び、それを用いて洗浄された基板を用いた高信頼性・高性能の磁気記録媒体とその磁気記録媒体の製造方法を提供することにある。
【０００７】
【課題を解決するための手段】
本発明は、これらの目的を達成するために、請求項１に記載の発明は、磁気記録媒体用ガラス系基板またはセラミック系基板を溶液により洗浄するための基板洗浄方法であって、前記基板は、該基板表面上に直接テクスチャ加工を施したものであり、前記溶液は、ｐＨ１〜５の有機酸系洗浄剤の水溶液であり、前記テクスチャ加工を施した基板を回転させて前記水溶液を滴下しながら、当該水溶液を研磨砥粒を含まない加工布に浸透させ、当該加工布を前記基板の表面に押し付けて前記基板を洗浄加工することにより、前記テクスチャ加工を施した基板の表面上に残存するダイア砥粒を含む残渣および微小突起を除去することを特徴とする。
【０００８】
また、請求項２に記載の発明は、請求項１に記載の基板洗浄方法において、前記有機酸系洗浄剤は、スルホン酸、クエン酸、リンゴ酸、又は、酢酸のうち少なくとも１つの有機酸を含有するものであることを特徴とする。
【０００９】
また、請求項３に記載の発明は、請求項２に記載の基板洗浄方法において、前記水溶液中の有機酸系洗浄剤濃度が、１〜２０％であることを特徴とする。
【００１１】
また、請求項４に記載の発明は、請求項１乃至３のいずれかに記載の基板洗浄方法において、前記加工布は、ウレタン、ポリエステル、ナイロンのうちいずれかの素材で構成されたものであることを特徴とする。
【００１２】
また、請求項５に記載の発明は、請求項１乃至４のいずれかに記載の基板洗浄方法において、前記加工布は、直径１０μｍ以下の極細繊維を紡織した織布、又は、該織布を起毛させた起毛布であることを特徴とする。
【００１３】
更に、請求項６に記載の発明は、請求項１乃至５のいずれかに記載の基板洗浄方法において、前記加工布を前記基板表面に押し付ける圧力が、１００〜１０００ｇ／ｃｍ２であることを特徴とする。
【００１４】
請求項７に記載の発明は、磁気記録媒体であって、請求項１乃至６のいずれかに記載の基板洗浄方法で洗浄された基板上に、少なくとも磁性層、保護層、及び、液体潤滑層を順次備えることを特徴とする。
【００１５】
また、請求項８に記載の発明は、請求項７に記載の磁気記録媒体において、前記基板は、５ｎｍ以上の突起物の数が３０μｍ角領域内で１０個以下であり、かつ、中心線平均粗さの値（Ｒａ）が０．２〜１ｎｍであることを特徴とする。
【００１６】
更に、請求項９に記載の発明は、磁気記録媒体の製造方法であって、請求項１乃至６のいずれかに記載の基板洗浄方法を用いて基板洗浄し、該洗浄後の基板上に、少なくとも磁性層、保護層、及び、液体潤滑層を順次形成することを特徴とする。
【００１７】
【発明の実施の形態】
以下に、図面を参照して、本発明の実施の形態について説明する。
【００１８】
本発明の基板洗浄方法は、磁気記録媒体用のガラス系又はセラミック系基板の洗浄方法に関する。この基板は、表面上に直接テクスチャ加工を施したものであり、洗浄に使用する溶液は、ｐＨ１〜５の有機酸系洗浄剤の水溶液であり、これにより、基板表面上に残存する残渣及び微小突起を除去することが可能である。
【００１９】
ここで使用される有機酸系洗浄剤は、スルホン酸、クエン酸、リンゴ酸、又は、酢酸の少なくとも１つを含有するものであることが好ましく、更に、水溶液の有機酸系洗浄剤濃度が、１〜２０％であることが好ましい。
【００２０】
このような組成と濃度の水溶液を研磨砥粒を含まない加工布に浸透させ、この加工布を高速で回転等する基板表面に接触させて洗浄を行ない、基板表面に残存する残渣や微小突起を除去する。ここで、加工布の素材としては、ウレタン、ポリエステル、ナイロンのうちいずれかの素材で構成されたものであることが好ましく、更に、この加工布は、直径１０μｍ以下の極細繊維を紡織した織布または、該織布を起毛させた起毛布であることがより好ましい。また、加工布と基板表面との接触圧力は、１００〜１０００ｇ／ｃｍ２であることが好ましい。
【００２１】
また、本発明の磁気記録媒体は、上述した基板洗浄方法で洗浄された基板を使用して、その表面上に磁気記録層や保護層や液体潤滑剤層等を備えて構成されたものである。なお、高信頼性・高精度の磁気記録媒体を得るためには、洗浄後の基板は、ＡＦＭを用いて３０μｍ角の表面形状を測定したときに観察される５ｎｍ以上の突起物の数が１０個以下であり、かつ、中心線平均粗さの値（Ｒａ）が０．２〜１ｎｍであることが特に好ましい。
【００２２】
更に、本発明の磁気記録媒体の製造方法は、上述した基板洗浄方法を用いて基板洗浄を行ない、その基板上に、少なくとも磁性層、保護層、及び、液体潤滑層を順次成膜して形成することを特徴とする。
【００２３】
以下に、本発明を実施例により更に詳細に説明する。
【００２４】
［実施例１］
テクスチャ加工によりガラス基板表面に溝形成を行い、その基板をスピンドルにチャックし３００ｒｐｍで回転させながら、ポリエステルおよびナイロンで構成される極細繊維の織布を起毛したものを２０ｍｍ／ｍｉｎの速度で送りながら、ゴム硬度４０°の押し付け部材を介して、押し付け圧力２ｋｇｆ／ｃｍ２で押し付け、有機酸を含んだｐＨ２の酸洗剤を５％の濃度に純水で希釈し、それを１５ｃｃ／ｍｉｎで滴下しながら２５秒間の洗浄を行った。
【００２５】
図１は、このようにして洗浄した基板と洗浄なしの各々の基板の表面粗さを、３０μｍ角の範囲でＡＦＭにより評価した結果であり、表1は、３０μｍ角での中心線平均粗さ（Ｒａ）、中心線上方向の高さ（Ｒｐ）、及び、溝のトータル高さ（Ｒｍａｘ）の数値データを纏めたものである。
【００２６】
【表１】
これらの結果から明らかなように、本発明の基板洗浄方法による洗浄を施すことで、ガラス基板表面上のＲａ、Ｒｐ、Ｒｍａｘにいずれの値をも低減でき、顕著な洗浄効果があることが確認された。
【００２８】
［実施例２］
実施例１で作製した洗浄あり及び洗浄なしの基板を用いて磁気記録媒体を作製し、その表面上の突起物の数を評価した。
【００２９】
磁気記録媒体は、ＤＣスパッタ装置を用い、基板を加熱し、その上に、ＮｉＰシード層、Ｃｒ系合金の下地層、ＣｏＣｒＰｔを含む磁性層、及び、カーボン保護層を順次積層して成膜し、その表面に潤滑剤を塗布して作製した。その磁気記録媒体の中心から半径１３．５〜３１．１ｍｍの範囲の領域を、ピエゾ素子により衝突エネルギーを検出できるグライドハイトテスト用ヘッドを用いて、周速一定にて０．３μ″で浮上させて突起検査を行った。
【００３０】
図２は、このようにして測定した各磁気記録媒体表面上の突起のヒットカウント数をグラフとして纏めたものであり、表２は、各々の基板を用いて作製した磁気記録媒体表面上の突起物の数を纏めたものである。なお、この評価に使用したテスターは、Ｓｏｎｙ Ｔｅｋｔｒｏｎｉｘ製ＤＳ４２００である。
【００３１】
【表２】
これらの結果から分るとおり、実施例１と同様に、本発明の基板洗浄方法で洗浄を行なうことで、基板表面上の突起（比較的高い高さを有する異物）が減少していることが確認できる。
【００３３】
［実施例３］
実施例２で突起物試験に用いた磁気記録媒体のエラー試験を、市販のＧＭＲヘッドを用いて行った。なお、記録密度は２５４ＫＦＣｌで、測定範囲は半径１５．２３〜３０．６ｍｍの領域、スライスレベルはＭＰ：６０％、ＥＰ：３０％である。また、テスターには、実施例２と同様に、Ｓｏｎｙ Ｔｅｋｔｒｏｎｉｘ製ＤＳ４２００を使用した。
【００３４】
図３は、このようにして測定した各磁気記録媒体のエラーカウント数をグラフとして纏めたものであり、表３は、各々の基板を用いて作製した磁気記録媒体のMissingパルス数及びExtraパルス数を纏めたものである。
【００３５】
【表３】
これらの結果から分るとおり、本発明の基板洗浄方法で洗浄を行なうことで、磁気記録媒体のエラー数が大幅に減少していることが確認でき、本発明の基板洗浄方法が、エラー低減に極めて有効であることが分かった。
【００３７】
［実施例４］
テクスチャ加工を施してガラス基板表面に溝形成を行い、実施例１で説明した組成の有機酸を洗浄剤として用いて洗浄した基板と、同一のテクスチャ加工を施した後に、フッ酸（無機酸）を洗浄剤として用いて洗浄した基板を準備し、これらの基板表面状態を比較した。なお、このときの基板表面に加えた圧力は８００ｇ／ｃｍ２である。
【００３８】
図４は、このようにして洗浄した基板表面の３０μｍ角領域をＡＦＭ及びＺｙｇｏにより評価した、中心線平均粗さ（Ｒａ）、中心線上の高さ（Ｒｐ）、溝のトータル高さ（Ｒｍａｘ）、及び、うねり成分（Ｗａ）の結果をグラフにしたものであり、表４は、図４に示した評価結果を数値データとして纏めたものである。
【００３９】
【表４】
これらの結果から分るとおり、フッ酸（無機酸）を使用すると、フッ酸がガラス基板表面を侵食してしまう結果、異常突起やうねりを増大させてしまうのに対して、本発明の基板洗浄方法による洗浄では、そのような不都合がなく良好な表面状態を維持しながら洗浄が行なわれている。
【００４１】
［実施例５］
テクスチャ加工によりガラス基板表面に溝形成を行い、実施例１で説明した有機酸を用いた洗浄剤の濃度を１〜５０％の範囲で変更して基板洗浄を行ない、その３０μｍ角領域の表面状態をＡＦＭにより評価した。
【００４２】
図５は、溶液中の洗浄剤濃度に対する基板表面粗さの測定結果であり、表５は、これらの数値データを纏めたものである。
【００４３】
【表５】
この結果から分るとおり、洗浄剤の濃度を上げすぎてしまうと、逆に表面上の突起や異物を発生させてしまうという結果になっている。この結果から、洗浄剤濃度は１〜２０％の範囲とすることが好ましい。
【００４５】
【発明の効果】
以上、説明したように、本発明の基板表面の洗浄方法によれば、ガラス系材料またはセラミック系材料の非磁性基板表面に、直接テクスチャ加工を行った基板を、テクスチャと同様の加工布と有機酸を含有させた洗浄剤とを用いてテクスチャ方式の洗浄を行うことで、表面上に残るダイア砥粒やスラリー等の残渣、および微小突起を除去することが可能となる。
【００４６】
また、この洗浄方法を採用する本発明の磁気記録媒体の製造方法によれば、ガラス系材料またはセラミック系材料の非磁性基板を用いた高記録密度対応の異方性磁気記録媒体を提供することが可能となる。
【図面の簡単な説明】
【図１】本発明の基板洗浄方法で洗浄した基板と洗浄なしの各々の基板の表面粗さを、３０μｍ角の範囲でＡＦＭにより評価した結果を示す図である。
【図２】本発明の基板洗浄方法で洗浄した基板と洗浄なしの基板上に作製した磁気記録媒体表面上の突起のヒットカウント数をグラフとして纏めた図である。
【図３】本発明の基板洗浄方法で洗浄した基板と洗浄なしの基板上に作製した磁気記録媒体のエラーカウント数をグラフとして纏めた図である。
【図４】本発明の基板洗浄方法で洗浄した基板と、フッ酸洗浄剤を用いて洗浄した基板表面の３０μｍ角領域をＡＦＭ及びＺｙｇｏにより評価した、中心線平均粗さ（Ｒａ）、中心線上の高さ（Ｒｐ）、溝のトータル高さ（Ｒｍａｘ）、及び、うねり成分（Ｗａ）の結果を示したグラフである。
【図５】本発明の基板洗浄方法における溶液中の洗浄剤濃度と、洗浄後の基板をＡＦＭにより評価した基板表面粗さとの関係を説明するための図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a substrate cleaning method, a magnetic recording medium, and a manufacturing method thereof. More specifically, the present invention relates to a method of cleaning a textured glass substrate or ceramic substrate, a magnetic recording medium using the same, and The present invention relates to a method for manufacturing a magnetic recording medium.
[0002]
[Prior art]
As the recording density of magnetic recording media increases, the size of 1 bit, which is the minimum unit of data written to the magnetic recording media, has become smaller. In magnetic recording media using glass-based substrates, isotropic media are the mainstream, but as the bit size becomes smaller, Resolution (ratio of HF output to LF output compared to anisotropic media such as aluminum-based substrates). ) Is low and the SNR (noise to signal ratio) is poor. This is because in order to obtain the same characteristics as an anisotropic medium in an isotropic medium, it is necessary to increase Mrt in the circumferential direction, resulting in an increase in the thickness of the magnetic layer, resulting in the magnetic film. This is because the medium noise increases. Therefore, it is necessary to produce an anisotropic medium on a glass substrate at a low cost. For example, magnetic recording in which an anisotropic medium of a glass substrate is produced by directly texturing the glass substrate. A method for manufacturing a medium has been proposed.
[0003]
On the other hand, in a general magnetic recording medium manufacturing process, as a substrate surface cleaning method after texture processing, there are a cup type or roll type scrub cleaning method, a chemical solution using a dip layer, or an immersion cleaning method using ultrasonic waves. Thus, processing residues such as diamond abrasive grains and slurry liquid remaining on the substrate surface are removed by texture processing.
[0004]
[Problems to be solved by the invention]
However, when the glass substrate is directly textured to produce the glass substrate anisotropic medium, the grooves formed by the texture processing are finer than the texture grooves of the conventional medium. The diamond abrasive grains and slurry liquid remaining in the grooves cannot be completely removed by the conventional cleaning method, and when a magnetic recording medium is used, defects such as GH defects and error defects due to these residuals occur. There was a problem that the product value was lost. Therefore, in the production of an anisotropic medium using a glass-based substrate, it is required to produce a highly reliable magnetic recording medium by improving the substrate cleaning level after texturing.
[0005]
The present inventors have studied the types of detergents and sponges used in conventional substrate cleaning methods such as cup-type and roll-type scrub cleaning and dip-type cleaning. The removal level was insufficient. In addition, although a cleaning experiment was carried out by increasing the concentration of hydrofluoric acid by the immersion cleaning method using hydrofluoric acid, which is generally used for cleaning glass substrates, although the foreign matter removal effect was slightly improved, hydrofluoric acid Etching caused the surface of the substrate to become rough and was not practical as a manufacturing method.
[0006]
The present invention has been made in view of such problems, and the object of the present invention is to obtain residues and fines such as diamond abrasive grains and slurry remaining on the surface of a substrate subjected to fine texture processing on the surface. To provide a substrate cleaning method capable of sufficiently removing protrusions, and to provide a highly reliable and high-performance magnetic recording medium using the substrate cleaned using the same, and a method of manufacturing the magnetic recording medium It is to provide.
[0007]
[Means for Solving the Problems]
In order to achieve these objects, the present invention provides a substrate cleaning method for cleaning a glass-based substrate or a ceramic-based substrate for a magnetic recording medium with a solution, wherein the substrate is , which was subjected directly texturing on the substrate surface, the solution, Ri aqueous der organic acid cleaning agent PH1～5, dropping the aqueous solution by rotating the substrate subjected to the texturing However, the aqueous solution is allowed to penetrate into a work cloth that does not include abrasive grains, and the work cloth is pressed against the surface of the substrate to wash the substrate, thereby remaining on the surface of the textured substrate. It is characterized by removing residues and fine protrusions containing diamond abrasive grains .
[0008]
The invention according to
[0009]
The invention described in claim 3 is the substrate cleaning method according to
[0011]
According to a fourth aspect of the present invention, in the substrate cleaning method according to any of the first to third aspects, the work cloth is made of any material selected from urethane, polyester, and nylon. It is characterized by that.
[0012]
The invention according to claim 5 is the substrate cleaning method according to any one of
[0013]
Furthermore, the invention according to claim 6 is the substrate cleaning method according to any one of
[0014]
A seventh aspect of the present invention is a magnetic recording medium, wherein at least a magnetic layer, a protective layer, and a liquid lubricating layer are formed on the substrate cleaned by the substrate cleaning method according to any one of the first to sixth aspects. Are sequentially provided.
[0015]
The invention according to claim 8 is the magnetic recording medium according to claim 7 , wherein the number of protrusions of 5 nm or more in the substrate is 10 or less in a 30 μm square region, and the center line average roughness The value (Ra) is 0.2 to 1 nm.
[0016]
Furthermore, the invention described in claim 9 is a method for manufacturing a magnetic recording medium, wherein the substrate is cleaned using the substrate cleaning method according to any one of
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0018]
The substrate cleaning method of the present invention relates to a method for cleaning a glass or ceramic substrate for a magnetic recording medium. This substrate is directly textured on the surface, and the solution used for cleaning is an aqueous solution of an organic acid cleaning agent having a pH of 1 to 5, whereby residues and microscopic residues remaining on the substrate surface can be obtained. It is possible to remove the protrusion.
[0019]
The organic acid detergent used here preferably contains at least one of sulfonic acid, citric acid, malic acid, or acetic acid, and the concentration of the organic acid detergent in the aqueous solution is It is preferable that it is 1 to 20%.
[0020]
An aqueous solution having such a composition and concentration is allowed to permeate a work cloth that does not contain abrasive grains, and the work cloth is brought into contact with the substrate surface that rotates at a high speed to perform cleaning. Residues and minute protrusions remaining on the substrate surface are removed. Remove. Here, it is preferable that the material of the work cloth is composed of any material of urethane, polyester, and nylon, and this work cloth is a woven cloth obtained by spinning ultrafine fibers having a diameter of 10 μm or less. Or it is more preferable that it is the raising cloth which raised this woven cloth. Moreover, it is preferable that the contact pressure of a work cloth and a substrate surface is 100-1000 g / cm < 2 >.
[0021]
In addition, the magnetic recording medium of the present invention is configured by using a substrate cleaned by the above-described substrate cleaning method and including a magnetic recording layer, a protective layer, a liquid lubricant layer, and the like on the surface thereof. . In order to obtain a highly reliable and highly accurate magnetic recording medium, the number of protrusions having a size of 5 nm or more observed on the cleaned substrate when a 30 μm square surface shape is measured using AFM is 10 or less. And the centerline average roughness value (Ra) is particularly preferably 0.2 to 1 nm.
[0022]
Furthermore, in the method for manufacturing a magnetic recording medium of the present invention, substrate cleaning is performed using the above-described substrate cleaning method, and at least a magnetic layer, a protective layer, and a liquid lubricating layer are sequentially formed on the substrate. It is characterized by doing.
[0023]
Hereinafter, the present invention will be described in more detail with reference to examples.
[0024]
[Example 1]
Grooves are formed on the surface of the glass substrate by texture processing, while the substrate is chucked on a spindle and rotated at 300 rpm, while a woven fabric of ultrafine fibers composed of polyester and nylon is fed at a speed of 20 mm / min. Then, it is pressed through a pressing member having a rubber hardness of 40 ° with a pressing pressure of 2 kgf / cm 2 , a
[0025]
FIG. 1 shows the results of evaluating the surface roughness of the substrate thus cleaned and each substrate without cleaning by AFM in the range of 30 μm square, and Table 1 shows the centerline average roughness at 30 μm square. Numerical data of (Ra), the height (Rp) in the upper direction of the center line, and the total height (Rmax) of the groove are collected.
[0026]
[Table 1]
As is clear from these results, it is confirmed that by performing the cleaning by the substrate cleaning method of the present invention, any value of Ra, Rp, Rmax on the surface of the glass substrate can be reduced and there is a remarkable cleaning effect. It was done.
[0028]
[Example 2]
A magnetic recording medium was prepared using the substrate with and without cleaning prepared in Example 1, and the number of protrusions on the surface was evaluated.
[0029]
The magnetic recording medium is formed by sequentially laminating a NiP seed layer, a Cr-based alloy underlayer, a CoCrPt-containing magnetic layer, and a carbon protective layer on a substrate using a DC sputtering apparatus. Then, a lubricant was applied to the surface. Using a glide height test head capable of detecting collision energy with a piezo element, a region with a radius of 13.5 to 31.1 mm from the center of the magnetic recording medium is levitated at a constant peripheral speed of 0.3 μ ″. The protrusion was inspected.
[0030]
FIG. 2 is a graph summarizing the hit counts of the protrusions on the surface of each magnetic recording medium measured in this way, and Table 2 shows the protrusions on the surface of the magnetic recording medium manufactured using each substrate. It summarizes the number of objects. In addition, the tester used for this evaluation is DS4200 made by Sony Tektronix.
[0031]
[Table 2]
As can be seen from these results, as in Example 1, by performing cleaning with the substrate cleaning method of the present invention, protrusions (foreign matter having a relatively high height) on the substrate surface are reduced. I can confirm.
[0033]
[Example 3]
An error test of the magnetic recording medium used in the protrusion test in Example 2 was performed using a commercially available GMR head. The recording density is 254 KFCl, the measurement range is an area with a radius of 15.23 to 30.6 mm, and the slice level is MP: 60% and EP: 30%. As a tester, DS4200 manufactured by Sony Tektronix was used as in Example 2.
[0034]
FIG. 3 is a graph summarizing the error count number of each magnetic recording medium measured as described above, and Table 3 shows the Missing pulse number and Extra pulse number of the magnetic recording medium manufactured using each substrate. Are summarized.
[0035]
[Table 3]
As can be seen from these results, it can be confirmed that the number of errors in the magnetic recording medium is greatly reduced by performing the cleaning with the substrate cleaning method of the present invention, and the substrate cleaning method of the present invention reduces errors. It was found to be extremely effective.
[0037]
[Example 4]
A groove is formed on the surface of the glass substrate by texture processing, and after the same texture processing as the substrate cleaned using the organic acid having the composition described in Example 1 as a cleaning agent, hydrofluoric acid (inorganic acid) Substrates cleaned using a cleaning agent were prepared, and the surface states of these substrates were compared. Note that the pressure applied to the substrate surface at this time is 800 g / cm 2 .
[0038]
FIG. 4 shows the center line average roughness (Ra), the height on the center line (Rp), and the total height of the groove (Rmax) evaluated by AFM and Zygo on the 30 μm square region of the substrate surface thus cleaned. The results of the swell component (Wa) are graphed, and Table 4 summarizes the evaluation results shown in FIG. 4 as numerical data.
[0039]
[Table 4]
As can be seen from these results, when hydrofluoric acid (inorganic acid) is used, hydrofluoric acid erodes the glass substrate surface, resulting in an increase in abnormal protrusions and undulations. In the cleaning by the method, there is no such inconvenience and the cleaning is performed while maintaining a good surface state.
[0041]
[Example 5]
Grooves are formed on the glass substrate surface by texture processing, and the substrate cleaning is performed by changing the concentration of the cleaning agent using the organic acid described in Example 1 in the range of 1 to 50%. The surface state of the 30 μm square region Was evaluated by AFM.
[0042]
FIG. 5 shows the measurement results of the substrate surface roughness with respect to the cleaning agent concentration in the solution, and Table 5 summarizes these numerical data.
[0043]
[Table 5]
As can be seen from this result, if the concentration of the cleaning agent is increased too much, conversely, protrusions and foreign matters on the surface are generated. From this result, the cleaning agent concentration is preferably in the range of 1 to 20%.
[0045]
【The invention's effect】
As described above, according to the substrate surface cleaning method of the present invention, a substrate that has been directly textured on a non-magnetic substrate surface of a glass-based material or a ceramic-based material is treated with a work cloth and an organic material that are similar to the texture. By performing a texture-type cleaning using an acid-containing cleaning agent, residues such as diamond abrasive grains and slurry remaining on the surface, and minute protrusions can be removed.
[0046]
In addition, according to the method of manufacturing a magnetic recording medium of the present invention employing this cleaning method, an anisotropic magnetic recording medium corresponding to a high recording density using a non-magnetic substrate made of a glass-based material or a ceramic-based material is provided. Is possible.
[Brief description of the drawings]
FIG. 1 is a diagram showing the results of AFM evaluation of the surface roughness of a substrate cleaned by the substrate cleaning method of the present invention and each substrate without cleaning in a range of 30 μm square.
FIG. 2 is a graph summarizing the hit count numbers of protrusions on the surface of a magnetic recording medium produced on a substrate cleaned by the substrate cleaning method of the present invention and on a substrate without cleaning.
FIG. 3 is a graph summarizing error counts of magnetic recording media prepared on a substrate cleaned by the substrate cleaning method of the present invention and a substrate without cleaning as a graph.
FIG. 4 shows a center line average roughness (Ra) on the center line, evaluated by AFM and Zygo on a substrate cleaned by the substrate cleaning method of the present invention and a 30 μm square region of the substrate surface cleaned using a hydrofluoric acid cleaning agent. It is the graph which showed the result of height (Rp) of this, the total height (Rmax) of a groove | channel, and a wave | undulation component (Wa).
FIG. 5 is a diagram for explaining the relationship between the concentration of a cleaning agent in a solution in the substrate cleaning method of the present invention and the substrate surface roughness obtained by evaluating the cleaned substrate by AFM.
Claims (9)
前記基板は、該基板表面上に直接テクスチャ加工を施したものであり、
前記溶液は、ｐＨ１〜５の有機酸系洗浄剤の水溶液であり、
前記テクスチャ加工を施した基板を回転させて前記水溶液を滴下しながら、当該水溶液を研磨砥粒を含まない加工布に浸透させ、当該加工布を前記基板の表面に押し付けて前記基板を洗浄加工することにより、前記テクスチャ加工を施した基板の表面上に残存するダイア砥粒を含む残渣および微小突起を除去することを特徴とする基板洗浄方法。A substrate cleaning method for cleaning a glass substrate or a ceramic substrate for a magnetic recording medium with a solution,
The substrate is subjected to texture processing directly on the substrate surface,
The solution, Ri aqueous der organic acid cleaning agent PH1～5,
While rotating the textured substrate and dropping the aqueous solution, the aqueous solution penetrates into a work cloth that does not contain abrasive grains, and the work cloth is pressed against the surface of the substrate to clean the substrate. In this way, the substrate cleaning method is characterized by removing residues and fine protrusions including diamond abrasive grains remaining on the surface of the textured substrate.
該洗浄後の基板上に、少なくとも磁性層、保護層、及び、液体潤滑層を順次形成することを特徴とする磁気記録媒体の製造方法。The substrate cleaning method according to any one of claims 1 to 6 and the substrate washed with,
A method for producing a magnetic recording medium, comprising: sequentially forming at least a magnetic layer, a protective layer, and a liquid lubricating layer on the cleaned substrate.
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| JP4828436B2 (en) * | 2007-01-11 | 2011-11-30 | 昭和電工株式会社 | Magnetic recording medium manufacturing method and magnetic recording medium |
| JP5192953B2 (en) * | 2007-09-14 | 2013-05-08 | 三洋化成工業株式会社 | Glass substrate cleaner for magnetic disk |
| FR3072089B1 (en) * | 2017-10-05 | 2022-03-04 | Eurokera | TEXTURED CERAMIC SHEET |
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