JP4125151B2 - Manufacturing method of structure - Google Patents

Description

【００３９】
表１に示すように、基板上に形成した窪みの配列の短い間隔と長い間隔に大きな差がない場合においては、Ａの試料のように陽極酸化による通常の細孔、すなわち直線性の良い柱状構造の細孔が得られた。一方、Ｂ〜Ｅの試料では細孔は形成過程において自己組織的に分岐し、試料の形状はおよそ図２で示す状態となった。また、Ｆの試料のように窪みの配列の短い間隔と長い間隔に大きな差がある場合においては、細孔は分岐するものの、図３に示すように基板上に形成した窪みの間を補間するように、意図しない細孔が形成されており、形成された細孔の配列の規則性が大きく乱れていることを確認した。
【００４０】
以上の結果より、本発明のナノ構造体の製造方法における、陽極酸化による細孔を自己組織的に分岐させる工程には、被陽極酸化層であるＡｌの膜厚が１μｍの場合においては長方状或いは斜方状に配列した、細孔形成開始点となる窪みの配列を、長い間隔が短い間隔の１．４〜２．０倍とすることが望ましいことを確認した。
【００４１】
次に、試料Ｂ〜Ｅについて下地層からの突起物の形成を行った。
Ｂ〜Ｅの試料を陽極としてホウ酸アンモニウム溶液中でそれぞれ陽極酸化を行うと、細孔により露出した下地層のＮｂとホウ酸アンモニウム溶液の界面において、ＮｂがＮｂイオンとなり、Ｎｂイオンが酸素と反応してＮｂ酸化物を形成する。このように酸化物が形成されることで露出した下地層部分は体積膨張し、図４に示すように細孔４１内に充填されてＮｂ酸化物４４による突起物を細孔内に形成する。この際、酸化物４２の高さは印加電圧に比例し、印加電圧５０Ｖで突起物の高さは約６０ｎｍ、７０Ｖで約１２０ｎｍ、１００Ｖで約１８０ｎｍである。本実施例では、印加電圧５０Ｖとし、約６０ｎｍの高さのＮｂ酸化物による突起物を形成した。
【００４２】
更に、リン酸とクロム酸の混合溶液に浸すことで、細孔の隔壁であるアルミナを全て溶解した。この状態で試料の断面をＦＥ−ＳＥＭで観測すると、Ｂ〜Ｅ全ての試料において図９に示すようにＮｂ酸化物による突起部９１と、細孔間に存在する十数ｎｍ程度の被陽極酸化層の残留突起９２による凸型構造が形成されていることが確認された。
【００４３】
形成された凸型構造は、分岐した細孔の底部、及び分岐した後の細孔で形成される長方状配列と同様の周期で、長い間隔方向及び短い間隔方向にそれぞれ１／２周期ずれた位置に存在していることになるので、陽極酸化開始時にＡｌ表面に形成した窪みよりも微細な間隔で存在しており、単位面積当たりに存在する突起の密度は、Ａｌ表面に形成した単位面積当たりに存在する窪みの密度の４倍となっている。
【００４４】
以上の結果より、形成過程において自己組織的に分岐する細孔を使用することで、細孔形成開始点を作製する際のパターンよりも、より高密度で微細なパターンを簡易に作製することが可能であることが示された。
【００４５】
＜実施例２＞
本実施例は陽極酸化による細孔の形成に関するものである。特に、被陽極酸化層の膜厚を変化させることで、形成される細孔の形状の変化を観測したものに関する。
実施例１と同様にＳｉ基板上にスパッタリング法により下地層としてＮｂを１００ｎｍ、Ｎｂの上にＡｌを成膜した。本実施例ではＡｌの膜厚を２μｍ，５００ｎｍ，２００ｎｍとした３種類の基板を用意した。
【００４６】
各膜厚の基板に対して、実施例１と同様に細孔形成開始点となる窪みを形成し、実施例１と同様に陽極酸化した後ポアワイド処理を行い、ＦＥ−ＳＥＭで試料を観測した。
その結果、Ａｌ膜厚が２μｍの試料においては、実施例１と同様の結果であり、長方状に配列した細孔形成開始点となる窪みの配列の、長い間隔が短い間隔の１．４〜２．０倍の範囲において、図２に示すような形成過程において自己組織的に分岐した細孔が得られた。
【００４７】
Ａｌの膜厚が５００ｎｍの試料においては、実施例１の結果と同様の傾向であったが、長方状に配列した細孔形成開始点となる窪みの配列の、長い間隔が短い間隔の１．４倍の試料では、細孔は十分に分岐せず、主に柱状の細孔が形成された。１．５〜２．０倍の範囲の試料では、図２に示すような形成過程において自己組織的に分岐した細孔が得られた。
【００４８】
Ａｌの膜厚が２００ｎｍの試料においては、Ａｌの膜厚が５００ｎｍの場合と同様の結果であり、長方状に配列した細孔形成開始点となる窪みの配列の、長い間隔が短い間隔の１．５〜２．０倍の範囲において、図２に示すような形成過程において自己組織的に分岐した細孔が得られた。
【００４９】
以上の結果より、被陽極酸化層であるＡｌの膜厚が１μｍ以上である場合においては、長方状に配列した細孔形成開始点となる窪みの配列の、長い間隔が短い間隔の１．４〜２．０倍の試料において、形成される細孔は図２に示すような形成過程において自己組織的に分岐した細孔となることを確認した。また、Ａｌの膜厚が５００ｎｍ以下の場合においては、長方状に配列した細孔形成開始点となる窪みの配列の、長い間隔が短い間隔の１．５〜２．０倍の試料において、形成される細孔は図２に示すような形成過程において自己組織的に分岐した細孔となり、１．４倍の試料においては、細孔が分岐する以前に被陽極酸化層の底部まで細孔が形成されてしまい、結果として柱状の細孔となることを確認した。
【００５０】
また、実施例１と同様に、分岐した細孔を有する試料において突起物の形成を行ったところ、実施例１と同様に図４に示すような下地層の酸化物による突起物の形成が確認された。
【００５１】
＜実施例３＞
本実施例は下地層からの突起物形成に関する。特にメッキにより、細孔内へ突起物を形成することに関する。
Ｓｉ基板上にメッキの電極となる下地層としてＣｕを５０ｎｍ、更にＣｕの上に被陽極酸化層としてＡｌを１μｍそれぞれスパッタリング法により成膜した。続いて実施例１と同様に、Ａｌ表面に１００ｎｍ×１６０ｎｍの間隔で長方状に配列した窪みを形成し、細孔がＣｕ下地層に到達するまで陽極酸化を行った。これにより実施例１のＣの試料と同様の形状の細孔が形成された。
【００５２】
次に試料を陰極とし、硫酸銅５水和物とホウ酸の混合溶液中にてＣｕのメッキを行った。電着を行うことで、メッキ物のＣｕが細孔底部から充填されて突起物となる。突起物の高さは電解液の濃度やメッキの電位など電着条件と電着時間によって制御可能であり、本実施例では突起物の高さが約５０ｎｍとなるようにメッキを行った。
【００５３】
続いて実施例１と同様に、リン酸とクロム酸の混合溶液に浸すことでアルミナを全て溶解し、試料の断面をＦＥ−ＳＥＭで観測したところ、実施例１と同様にメッキ物のＣｕによる突起物と被陽極酸化層の残留突起による凸型構造が形成されていることが確認された。
以上の結果より、下地層からの突起物の形成においてメッキを利用することも可能であることが確認された。
【００５４】
＜実施例４＞
本実施例は、実施例１で作製した凸型構造のパターンを利用したスタンパに関するものである。
実施例１で作製したＣの試料を利用した凸型構造のパターンを有する試料に、Ｗを１０ｎｍスパッタリング法により成膜することで、図１０に示すように突起部１０１の補強を行い、これをスタンパとした。
【００５５】
次にパターンを転写する基板として、Ａｌ膜上にスピンコート法でレジストを７０ｎｍの厚さで配置した基板を用意し、レジスト上にＷにて補強した試料を押し付けることで、試料の凸部をレジストの表面に凹部として転写した。このとき、レジストの凹部は概ねＡｌまで到達してＡｌが露出しており、露出したＡｌのドライエッチングを行うことでレジスト上の凹部をＡｌに転写した。
【００５６】
レジストを除去した後、Ａｌ膜表面をＦＥ−ＳＥＭで観測すると、スタンパの突起部のうち下地層Ｎｂ酸化物による突起部分のみ構造が転写されていることが確認された。
また、実施例１において、下地層のＮｂ酸化物による突起部の高さを約２０ｎｍとした試料において同様の検討をおこなったところ、下地層のＮｂ酸化物による突起部と、被陽極酸化層の残留突起による突起部の全てがＡｌ膜の表面に凹部として転写されていた。
【００５７】
以上の結果より、実施例１において作製した凸型構造を有するナノ構造体をスタンパとして利用可能であることを確認した。また、本実施例で作製したスタンパを利用して形成したＡｌ膜表面の凹部を陽極酸化の細孔形成開始点とすることで、規則的に配列した細孔を形成することも可能である。
【００５８】
＜実施例５＞
本実施例は、実施例１で作製した凸型構造のパターンを利用した磁気記録媒体に関するものである。
本実施例では、実施例１で作製したＣの試料を利用した凸型構造のパターンを有する試料に、高い垂直磁気異方性を有する磁性体ＣｏＣｒＰｔを５０ｎｍスパッタリング法により成膜することで、図８に示すように突起部分８２の形状を反映した磁性層を形成した。このとき、突起部分８２の密度は約８０Ｇｄｏｔ／ｉｎ²であった。
【００５９】
続いて試料の基板に対して垂直方向に８ｋＯｅの磁場を印加した後、ゼロ磁場の状態にし、記録部分８３の残留磁化状態をＭＦＭ（磁気力顕微鏡）を使用して観測した。ＭＦＭ像より、記録部分の磁化は全て印加磁場の方向に向いていることが確認された。更にこの状態から、逆方向に８ｋＯｅの磁場を印加した後、ゼロ磁場の状態にし、記録部分８３の残留磁化状態をＭＦＭ（磁気力顕微鏡）を使用して観測したところ、記録部分の磁化は全て反転しており、印加磁場の方向に向いていた。また、これらのＭＦＭ像において、隣接する記録部分８３間における磁気的干渉による磁化反転も確認されず、一つの突起部分８２上に形成された記録部分８３に対して１ビットを記録させるパターンドメディアとして利用することも可能であると確認できた。
【００６０】
以上の結果より、本発明による凸型構造のパターンに磁性体を堆積させることで作製したナノ構造体に記録用磁気ヘッドを利用して記録部分に対して磁場を印加し、これを再生用ヘッドで読み取ることで磁気記録媒体として使用可能であることが確認された。
また、本発明によるナノ構造体を利用した磁気記録媒体の記録方式は、本実施例のように垂直記録方式に限定されるものではなく、面内記録方式であっても構わない。
【００６１】
【発明の効果】
以上説明した様に、本発明により、自己組織的に分岐する細孔を利用することで、凹凸構造を有するナノ構造体を、より簡易に且つ微細に製造することが可能となる。
また、本発明による凹凸構造を有するナノ構造体を利用したスタンパ、及び磁気記録媒体も作製することが可能である。
【図面の簡単な説明】
【図１】本発明のナノ構造体の製造方法における基板上に形成した窪みの模式図である。
【図２】自己組織的に分岐した細孔の模式図である。
【図３】意図しない部分に形成された細孔の模式図である。
【図４】細孔内への突起物形成の模式図である。
【図５】細孔内への突起物形成の模式図である。
【図６】下地層からの突起物による凸型構造の模式図である。
【図７】下地層からの突起物と被陽極酸化層の残留突起物による凸型構造の模式図である。
【図８】本発明による凸型パターンを使用した磁気記録媒体の模式図である。
【図９】Ｎｂ酸化物と被陽極酸化層の残留突起による凸型構造の模式図である。
【図１０】突起部を補強した状態の模式図である。
【符号の説明】
１１ 基板
１２ 窪み
１３ 配列の短い間隔
１４ 配列の長い間隔
２１ 二股に分岐した細孔
２２ 二股に分岐する以前の細孔
２３ アルミナ
２４ 分岐により残ったアルミナ部分
２５ 下地基板
２６ 残留突起
２７ 残留突起存在位置
３１ 意図しない部分に形成された細孔
３２ 二股に分岐した細孔
３３ 二股に分岐する以前の細孔
３４ 分岐により残ったアルミナ部分
４１ 細孔
４２ 下地層
４３ アルミナ
４４ 酸化物
４５ 残留突起
５１ 下地層
５２ 被陽極酸化層
５３ 細孔
５４ 突起物
５５ 残留突起
５６ アルミナ
６１ 被陽極酸化層
６２ アルミナ
６３ 下地層
６４ 突起物
６５ 残留突起
６６ 細孔
７１ 下地層
７２ 突起物
７３ 被陽極酸化層
７４ 残留突起
７５ アルミナ
７６ 細孔
８１ 磁性体
８２ 突起部分
８３ 記録部分
８４ 残留突起
８５ 下地層
９１ 突起部
９２ 残留突起
９３ 下地層
１０１ 突起部
１０２ 残留突起
１０３ 下地層
１０４ タングステン[0001]
BACKGROUND OF THE INVENTION
  The present invention has a nanoscale uneven structureManufacturing method of structureAbout.
[0002]
[Prior art]
When a workpiece is used as an anode and a voltage is applied (anodized) in an acidic solution, an anodized film having nanoscale pores is obtained. In this way, the nanostructures that are naturally formed, that is, self-organized, exceed artificial nanostructure technologies such as photolithography, electron beam exposure, and X-ray exposure used in semiconductor processes, etc. It has the potential to realize fine and special structures, and is attracting attention as a new nanostructure technology.
[0003]
For example, it is known that when a substrate mainly composed of Al is anodized in an acidic solution such as sulfuric acid, oxalic acid or phosphoric acid, a porous anodic oxide film having numerous pores is formed (for example, Non-patent document 1). This porous film is characterized by a unique geometric structure in which extremely fine cylindrical pores (alumina nanoholes) with a diameter of several nanometers to several hundred nanometers are arranged in parallel at intervals of several tens of nanometers to several hundred nanometers. Is to have. And this pore has a high aspect ratio and is excellent also in the uniformity of the diameter of a cross section.
[0004]
The structure of the porous film can be controlled to some extent by changing the anodizing conditions. For example, it is known that the pore interval can be controlled by an anodizing voltage, the pore depth can be controlled by an anodizing time, and the pore diameter can be controlled to some extent by pore wide processing. Here, the pore wide treatment is an etching treatment of alumina, and usually a wet etching treatment with phosphoric acid is often used.
[0005]
Furthermore, in order to improve the verticality, linearity and independence of the pores of the porous film, a method of performing two-step anodic oxidation, that is, once removing the porous film formed by anodic oxidation, anodizing again. And a method for producing a porous film having pores exhibiting better verticality, linearity, and independence has been proposed (see, for example, Non-Patent Document 2). Here, in this method, using the fact that the depression of the substrate mainly composed of Al that is formed when removing the anodic oxide film formed by the first anodic oxidation is the starting point of pore formation for the second anodic oxidation. Yes.
[0006]
Filling the pores obtained by anodic oxidation as described above with metals, semiconductors, etc., such as magnetic recording media, magnetic sensors, EL light emitting elements, electrochromic elements, optical elements, solar cells, gas sensors, etc. Applications to various nanodevices are expected. For this purpose, a technique for regularly arranging the pores of the porous film in a desired pattern is required, and many patterning methods have been studied in order to improve the controllability of the pore shape, spacing and pattern. Yes. In particular, by pressing a stamper having a concavo-convex structure on a substrate to be processed as proposed in Patent Document 1, the structure of the stamper is transferred onto the substrate to produce a pore formation start point. Depending on the structure of the stamper, it is possible to produce a finer pattern more easily than photolithography and electron beam exposure, and the stamper can be used repeatedly, which is considered to be a very powerful patterning method. ing.
[0007]
In patterning using a stamper typified by the above-mentioned Patent Document 1, irregularities are formed by patterning a high-strength SiC substrate by electron beam exposure and then dry etching, and this is used as a stamper. However, since it is a limit of several tens of nanometers to draw a regular pattern by electron beam exposure, and it takes a long time to process a larger area, a simpler stamper manufacturing method is required. .
[0008]
Further, in Patent Document 2, a porous film such as an anodic oxide film is used as a matrix, and a pillar-shaped polymer negative mold is produced by removing the matrix after forming a polymer in the pores. Proposal of a method for producing metal oxides having pores with the same pattern as the matrix by dissolving and removing the negative mold by infiltrating the metal oxide sol into the gel and forming a gel. Has been. However, even in such a method, when an anodic oxide film is used as a base porous film, electron beam exposure or stamper patterning is required, and the negative mold is dissolved and removed each time the structure is transferred. There is no advantage that it can be used repeatedly like a stamper, and the throughput is not good.
[0009]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-121292 (page 9)
[Patent Document 2]
JP-A-6-32675 (Page 6)
[Non-Patent Document 1]
R. C. Furneaux, W.M. R. Rigby & A. P. Davidson “NATURE” Vol. 337, p. 147, 1989 (R Sea Furnault, Double Ear Rigby, AP Davidson)
[Non-Patent Document 2]
“Japan Journal of Applied Physics”, Vol. 35, Part2, No1B, p. l126-l129, January 15, 1996
[0010]
[Problems to be solved by the invention]
  The object of the present invention is to solve these problems, and to produce a structure having a regular nanoscale uneven structure more easily and finely than before.Provide a way.
[0011]
[Means for Solving the Problems]
The problems of the conventional method described above are solved by the following method according to the present invention.
The first invention of the present invention relates to a method for manufacturing a structure.
[0012]
  That is, the present inventionIn the method of manufacturing a structure that can include the step of anodizing a to-be-anodized film containing Al as a main component,
Preparing a member having the anodized film on the underlayer;
Forming a plurality of depressions regularly arranged on the anodized film;
The step of forming the pores branched toward the base layer by anodizing the anodic oxide film, using the depression as a starting point for pore formation,
Forming a protrusion on the foundation layer exposed at the bottom of the branched pores;
Including a step of removing the partition walls of the poresThis is a method for manufacturing a structure.
[0014]
Furthermore, the structure manufacturing method further includes a step of forming a protrusion in the pore from an underlayer provided under the anodized film after the formation of the pore. It is a manufacturing method.
Further, the structure is a method for producing a structure, characterized in that the base layer contains Nb, W, Ti, Ta, Mo, Zr, or Hf as a main component.
In the structure manufacturing method, the structure forming method is characterized in that the step of forming protrusions in the pores from the underlayer is oxidation of the underlayer.
[0015]
Or it is a manufacturing method of the structure characterized by the above-mentioned foundation layer being an electroconductive metal.
Further, in the method for manufacturing a structure, the step of forming protrusions in the pores from the underlayer is electrodeposition.
And in the manufacturing method of said structure, it is a manufacturing method of the structure characterized by forming the depression arranged in the shape of a rectangle or rhombus on this board | substrate.
Furthermore, in the manufacturing method of the structure described above, depressions arranged in a rectangular shape or a diagonal shape in which a long interval is 1.4 to 2.0 times a short interval are formed on the substrate. It is a manufacturing method of a structure.
[0016]
Further, in the above structure manufacturing method, anodization is performed by applying an anodization voltage corresponding to a short interval of the array in the rectangular or oblique array of depressions formed on the substrate. This is a manufacturing method of the structure.
In the structure manufacturing method described above, in the step of removing the anodized layer, the protrusions formed from the base layer on the substrate and the protrusion structures due to residual protrusions mainly composed of Al are exposed. It is a manufacturing method of the structure characterized by forming.
Further, the structure manufacturing method is characterized in that a material different from the structure is deposited on the structure manufactured by the structure manufacturing method.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
Since the structure of the present invention includes a nanostructure as a representative structure, the nanostructure will be described.
[0019]
<About manufacturing method of nanostructure>
A method for producing a nanostructure according to the present invention will be described with reference to the drawings.
It is a schematic diagram of the hollow formed on the board | substrate in the manufacturing method of the nanostructure of this invention.
[0020]
First, as shown in FIG. 1, on a substrate 11 that is an anodic oxide containing Al as a main component, a recess 12 that is a pore formation starting point is formed in a rectangular shape or an oblique shape. Examples of the method for forming the recess 12 include patterning by electron beam exposure, patterning by FIB (focused ion beam), or a method of transferring a structure by pressing a stamper having already patterned protrusions onto the substrate surface. The method is not particularly limited as long as the pore formation start point can be formed.
[0021]
In addition, the formation start point of the pores by anodic oxidation is formed by forming a depression on the surface of the anodized film, forming a mask on the surface, or forming the anodized film on a substrate having predetermined irregularities, It is obtained by forming irregularities corresponding to the irregularities on the anodized film.
[0022]
Next, the substrate on which the starting point is formed is anodized to form pores. At this time, in the rectangular or rhombic arrangement of the depressions formed on the substrate shown in FIG. It is desirable to apply an anodic oxidation voltage corresponding to 13. There is a relationship of approximately 2R = 2.5 × V between the anodic oxidation voltage V [Volt] and the interval 2R [nm] between the formed pores. For example, the depression is formed in a rectangular shape with a period of 100 nm × 150 nm. When arranged, it is desirable that the anodic oxidation voltage be 40V. As a result, the pores formed are branched in a self-organizing manner during the formation process, and the bifurcated pores in the state shown in FIG. 2 are formed. Here, the residual protrusion 26 in FIG. 2 is a portion of the anodized layer that remains without being oxidized by the anodic oxidation process, and exists at a residual protrusion existence position 27 indicated by B-B ′. That is, it exists in the position which shifted | deviated 1/2 period in the long space | interval direction and the short space | interval direction, respectively with the same period as the rectangular array formed with the pore after branching.
[0023]
At this time, when an anodizing voltage corresponding to the long interval 14 of the array is applied, the formed pores tend to be less likely to branch than when an anodizing voltage corresponding to the short interval 13 is applied.
[0024]
Here, the short interval 13 of the array is the interval between a certain recess and the recess in the first proximity, and the long interval 14 of the array is the interval between the recess in the second proximity. Define. The rectangular array is a case where the directions of the short interval 13 and the long interval 14 form an angle of 90 degrees, and a case where the direction is other than 90 degrees is defined as an oblique array. To do.
[0025]
Whether or not the pores due to anodization branch in a self-organizing manner depends not only on the above-described anodization voltage but also on the interval between the depressions formed on the substrate. In the rectangular or rhombic arrangement of the depressions, if the short interval and the long interval are greatly different, the pores are branched, but also in an unintended part such as a region between the long intervals as shown in FIG. Since the pores 31 are formed and the regularity is disturbed, it is not desirable. Conversely, when the short interval and the long interval are substantially equal, the pores do not branch, and columnar pores are obtained. In addition, it is also related to the thickness of the anodized layer. When the film thickness is small, the pores reach the bottom of the anodized layer before the pores branch, and as a result, columnar thin films are formed. There is a tendency to form pores. As a result of the study by the present inventors, there are some differences depending on the anodizing conditions, the thickness of the layer to be anodized, and the interval between the depressions, but if the long interval is smaller than 1.4 times the short interval, It was confirmed that the holes tend not to branch. It was also confirmed that when the long interval is larger than 2.0 times the short interval, the formation of pores in the unintended portion starts and the regularity is disturbed. In other words, pores are not formed in unintended portions within the range of 1.4 to 2.0 times longer intervals than short intervals, and pores branched in a self-organizing manner can be obtained in the formation process. It was confirmed. It was also confirmed that when an anodizing voltage corresponding to a long interval was applied, the above-mentioned pores were obtained when the long interval was 1.7 to 2.0 times the short interval.
[0026]
In order to fabricate a substrate mainly composed of Al used for anodization, various film formation methods such as resistance vapor deposition, sputtering, and CVD are possible. A method that can be formed is preferred. Further, although there is no particular limitation on the film thickness of the film mainly composed of Al that becomes the anodized layer, the anodic oxidation treatment time becomes longer as the film thickness increases, so it is about several tens nm to several μm. It is preferable to do. More preferably, it is the range of 30 nm-1 micrometer.
[0027]
Next, the protrusions formed from the underlayer in the pores produced as described above will be described.
A metal containing Nb, W, Ti, Ta, Mo, Zr, or Hf as a main component is used as the underlayer, and as shown in FIG. 4, the underlayer 42 is exposed by the pores 41 formed by anodization. From the state, the underlayer 42 is oxidized in a gas containing oxygen as a main component. Alternatively, the underlayer 42 is oxidized by anodizing the underlayer 42 in a solution that does not attack the alumina 43 that is the partition walls of the pores. As a result, the oxidized base layer 42 becomes an oxide 44 and its volume increases, so that it grows to fill the inside of the pores 41 and becomes a protrusion from the base layer 42. When oxidation is performed in a solution, it is preferable to use ammonium borate, ammonium tartrate, an aqueous ammonium citrate solution, or the like.
[0028]
In addition to the above method, as shown in FIG. 5, a conductive metal is disposed under the anodized layer 52 as a base layer 51, and the metal is formed into pores 53 by plating using the exposed base layer 51 as an electrode. It is possible to produce the protrusion 54 by filling the bottom.
[0029]
Finally, as shown in FIG. 6, when the alumina 62 of the anodized layer 61 is removed by wet etching with a phosphoric acid aqueous solution or the like, a convex structure is formed by the protrusions 64 from the base layer 63. The convex structure thus formed is a convex pattern that is twice or more finer than the concave pattern formed on the substrate by electron beam exposure or the like as a starting point for forming anodized pores. As described above, in the present invention, by combining artificial patterning and self-organization, a nanoscale convex pattern having the same protrusion density (number of protrusions per unit area) can be obtained only by artificial patterning. In addition to being easily formed, there is a possibility that a fine pattern exceeding the limit of artificial patterning such as electron beam exposure may be formed in some cases.
[0030]
In addition, after forming the pore formation start point in a large area by photolithography, the pores are branched in a self-organized manner by the process of the present invention, and a convex pattern is formed by protrusions from the underlayer, It is also possible to produce a pattern of an electron beam exposure region that exceeds the limits of photolithography over a large area.
[0031]
Further, as shown in FIG. 7, when the projection 72 is formed from the base layer 71, the height of the projection 72 is made substantially the same as the height of the residual projection 74 of the anodized layer 73, and as described above, the anode When the alumina 75 of the oxide layer 73 is removed by wet etching or the like, a finer convex pattern is formed.
[0032]
The convex pattern produced in this way can be used as a stamper. For example, the film is pressed onto an anodized film containing Al as a main component, or a resist provided on the anodized film, and may be projected on the anodized film by performing a process such as dry etching in some cases. By forming a concave pattern corresponding to the mold pattern and using this as a starting point for forming an anodized pore, it is possible to form a pore corresponding to the produced convex pattern.
[0033]
In addition, when using as a stamper, if the protrusions alone do not have the necessary strength for pressure bonding, the protrusions can be covered by depositing a high-strength material such as W on the protrusions. desirable.
[0034]
Further, the convex pattern produced according to the present invention is not only used as a stamper, but also a projection 81 is formed as a recording part 83 by forming a magnetic material 81 on the convex pattern as shown in FIG. A magnetic recording medium such as a patterned medium is also possible.
[0035]
【Example】
Hereinafter, the present invention will be described with reference to examples.
[0036]
<Example 1>
This example relates to the formation of pores by anodic oxidation.
Fabricated by depositing Nb with a thickness of 100 nm as an underlayer on a Si substrate by sputtering and further forming 1 μm of Al on Nb, and then forming recesses on the Al surface as pore formation starting points by anodization. did. In this embodiment, in this embodiment, SiC is patterned by electron beam exposure to produce a stamper having projections arranged in a rectangular shape, and the stamper is attached to the Al surface with a hydraulic press machine. By pressing against the Al surface, the protrusions of the stamper were transferred to the Al surface. At this time, samples A to F in which the intervals between the stamper protrusions were changed were prepared.
[0037]
Anodization was performed on the samples A to F by applying an anodic oxidation voltage of 40 V at 16 ° C. in a 0.3 mol / L oxalic acid aqueous solution. Here, the anodic oxidation voltage of 40 V is an anodic oxidation voltage corresponding to a short interval of 100 nm, that is, an array of depressions, from the relational expression of 2R = 2.5 × V. After the anodic oxidation, a pore wide treatment was performed by immersing in a 0.5 wt% phosphoric acid aqueous solution for 40 minutes. Then, the surface and cross-sectional shape of the sample were observed with FE-SEM (field emission scanning electron microscope). The results are shown in Table 1.
[0038]
[Table 1]

[0039]
As shown in Table 1, in the case where there is no significant difference between the short interval and the long interval of the depressions formed on the substrate, normal pores formed by anodization like the sample A, that is, a columnar shape with good linearity. Structured pores were obtained. On the other hand, in the samples B to E, the pores branched in a self-organizing manner during the formation process, and the shape of the sample was in the state shown in FIG. Further, when there is a large difference between the short interval and the long interval of the depressions as in the F sample, the pores are branched, but interpolation is performed between the depressions formed on the substrate as shown in FIG. Thus, it was confirmed that unintended pores were formed and the regularity of the arrangement of the formed pores was greatly disturbed.
[0040]
From the above results, in the method of manufacturing the nanostructure of the present invention, the step of self-organizing the pores by anodic oxidation is longer when the thickness of the anodic oxidation layer is 1 μm. As a result, it was confirmed that it is desirable that the arrangement of the depressions, which are arranged in the shape of or in the form of rhombic, as the pore formation start point, is 1.4 to 2.0 times the short interval.
[0041]
Next, the protrusions from the underlayer were formed for Samples B to E.
When anodization was performed in an ammonium borate solution using the samples B to E as anodes, Nb became Nb ions at the interface between the Nb and ammonium borate solutions exposed in the pores, and the Nb ions became oxygen and oxygen. Reaction forms Nb oxide. The underlying layer portion exposed by the formation of oxide in this manner expands in volume, and as shown in FIG. 4, the pores 41 are filled to form protrusions of the Nb oxide 44 in the pores. At this time, the height of the oxide 42 is proportional to the applied voltage. When the applied voltage is 50 V, the height of the protrusion is about 60 nm, 70 V is about 120 nm, and 100 V is about 180 nm. In this example, the protrusion was made of Nb oxide with an applied voltage of 50 V and a height of about 60 nm.
[0042]
Furthermore, all the alumina which is a pore partition was melt | dissolved by immersing in the mixed solution of phosphoric acid and chromic acid. When the cross section of the sample is observed with FE-SEM in this state, as shown in FIG. 9, in all the samples B to E, as shown in FIG. It was confirmed that a convex structure was formed by the residual protrusions 92 of the layer.
[0043]
The formed convex structure has the same period as the rectangular array formed by the bottom of the branched pores and the branched pores, and is shifted by 1/2 period in the long interval direction and the short interval direction, respectively. Therefore, the density of protrusions existing per unit area is the unit formed on the Al surface. It is four times the density of the depressions existing per area.
[0044]
From the above results, it is possible to easily create a finer and finer pattern than the pattern used when creating the pore formation starting point by using pores that self-organize in the formation process. It was shown to be possible.
[0045]
<Example 2>
This example relates to the formation of pores by anodic oxidation. In particular, the present invention relates to an observation of changes in the shape of the formed pores by changing the film thickness of the anodized layer.
As in Example 1, Nb was deposited to a thickness of 100 nm on the Si substrate by sputtering and Al was deposited on the Nb. In this embodiment, three types of substrates with Al film thicknesses of 2 μm, 500 nm, and 200 nm were prepared.
[0046]
A recess serving as a pore formation starting point was formed on the substrate having each film thickness in the same manner as in Example 1. After anodizing in the same manner as in Example 1, pore-wide treatment was performed, and the sample was observed with FE-SEM. .
As a result, in the sample having an Al film thickness of 2 μm, the result is the same as that of Example 1, and the array of the depressions serving as the formation start points of the pores arranged in a rectangular shape has a long interval of 1.4. Within a range of up to 2.0 times, self-organized fine pores were obtained in the formation process as shown in FIG.
[0047]
In the sample having the Al film thickness of 500 nm, the same tendency as the result of Example 1 was obtained. In the 4-fold sample, the pores were not sufficiently branched, and mainly columnar pores were formed. In the sample in the range of 1.5 to 2.0 times, self-organized fine pores were obtained in the formation process as shown in FIG.
[0048]
In the sample with the Al film thickness of 200 nm, the result is the same as when the Al film thickness is 500 nm. In the range of 1.5 to 2.0 times, self-organized fine pores were obtained in the formation process as shown in FIG.
[0049]
From the above results, in the case where the film thickness of Al as the anodized layer is 1 μm or more, the long interval of the recesses that are the formation start points of the pores arranged in a rectangular shape is the short interval 1. In the sample of 4 to 2.0 times, it was confirmed that the pores formed became self-organized branched pores in the formation process as shown in FIG. Further, in the case where the film thickness of Al is 500 nm or less, in the sample in which the long interval is 1.5 to 2.0 times the short interval in the array of depressions that are the formation start points of the pores arranged in a rectangular shape, The pores to be formed are self-organized branched pores in the formation process as shown in FIG. 2, and in the 1.4 times sample, the pores reached the bottom of the anodized layer before the pores were branched. As a result, it was confirmed that columnar pores were formed.
[0050]
Further, as in Example 1, when a protrusion was formed on a sample having branched pores, it was confirmed that the protrusion was formed by an oxide in the underlayer as shown in FIG. It was done.
[0051]
<Example 3>
This example relates to the formation of protrusions from the underlayer. In particular, it relates to forming protrusions in the pores by plating.
On the Si substrate, 50 nm of Cu was formed as a base layer to be an electrode for plating, and further 1 μm of Al was formed on Cu as an anodized layer by sputtering. Subsequently, in the same manner as in Example 1, depressions arranged in a rectangular shape at intervals of 100 nm × 160 nm were formed on the Al surface, and anodization was performed until the pores reached the Cu underlayer. As a result, pores having the same shape as the sample C of Example 1 were formed.
[0052]
Next, Cu was plated in a mixed solution of copper sulfate pentahydrate and boric acid using the sample as a cathode. By performing electrodeposition, Cu of the plated product is filled from the bottom of the pores to form protrusions. The height of the protrusions can be controlled by the electrodeposition conditions such as the concentration of the electrolytic solution and the plating potential and the electrodeposition time. In this example, plating was performed so that the height of the protrusions was about 50 nm.
[0053]
Subsequently, as in Example 1, all the alumina was dissolved by immersing in a mixed solution of phosphoric acid and chromic acid, and the cross section of the sample was observed with FE-SEM. It was confirmed that a convex structure was formed by the protrusions and residual protrusions of the anodized layer.
From the above results, it was confirmed that plating can be used in the formation of protrusions from the underlayer.
[0054]
<Example 4>
The present embodiment relates to a stamper that uses the pattern of the convex structure manufactured in the first embodiment.
The protrusion 101 is reinforced as shown in FIG. 10 by depositing W by a 10 nm sputtering method on a sample having a convex structure pattern using the sample C prepared in Example 1. A stamper.
[0055]
Next, as a substrate to which the pattern is transferred, a substrate in which a resist is arranged with a thickness of 70 nm by spin coating on an Al film is prepared, and a sample reinforced with W is pressed onto the resist so that a convex portion of the sample is formed. Transferred as a recess on the resist surface. At this time, the concave portion of the resist almost reached Al and Al was exposed, and the concave portion on the resist was transferred to Al by performing dry etching of the exposed Al.
[0056]
After removing the resist, the surface of the Al film was observed by FE-SEM, and it was confirmed that the structure was transferred only to the projecting portion of the base layer Nb oxide among the projecting portions of the stamper.
Further, in Example 1, a similar study was performed on a sample in which the height of the protruding portion of the base layer made of Nb oxide was about 20 nm. All the protrusions due to the remaining protrusions were transferred as recesses on the surface of the Al film.
[0057]
From the above results, it was confirmed that the nanostructure having a convex structure produced in Example 1 can be used as a stamper. In addition, it is also possible to form regularly arranged pores by using the recesses on the surface of the Al film formed by using the stamper produced in this example as the anodic oxidation pore formation starting point.
[0058]
<Example 5>
The present embodiment relates to a magnetic recording medium using the convex structure pattern manufactured in the first embodiment.
In this example, a magnetic material CoCrPt having a high perpendicular magnetic anisotropy is formed on a sample having a convex structure pattern using the C sample prepared in Example 1 by a 50 nm sputtering method. As shown in FIG. 8, a magnetic layer reflecting the shape of the protruding portion 82 was formed. At this time, the density of the protruding portion 82 is about 80 Gdot / in.²Met.
[0059]
Subsequently, after applying a magnetic field of 8 kOe in a direction perpendicular to the sample substrate, a zero magnetic field was applied, and the residual magnetization state of the recording portion 83 was observed using an MFM (magnetic force microscope). From the MFM image, it was confirmed that the magnetization of the recording part was all in the direction of the applied magnetic field. Further, from this state, after applying a magnetic field of 8 kOe in the opposite direction, the magnetic field was changed to zero magnetic field, and the residual magnetization state of the recording portion 83 was observed using an MFM (magnetic force microscope). It was reversed and turned in the direction of the applied magnetic field. Further, in these MFM images, the magnetization reversal due to magnetic interference between the adjacent recording portions 83 is not confirmed, and the patterned medium that records 1 bit on the recording portion 83 formed on one protruding portion 82 It was confirmed that it could be used as
[0060]
Based on the above results, a magnetic field is applied to the recording portion using the recording magnetic head to the nanostructure produced by depositing the magnetic material on the convex structure pattern according to the present invention, and this is used as the reproducing head. It was confirmed that it can be used as a magnetic recording medium.
Further, the recording system of the magnetic recording medium using the nanostructure according to the present invention is not limited to the perpendicular recording system as in this embodiment, and may be an in-plane recording system.
[0061]
【The invention's effect】
As described above, according to the present invention, a nanostructure having a concavo-convex structure can be more easily and finely manufactured by utilizing self-organized fine pores.
In addition, a stamper using a nanostructure having a concavo-convex structure according to the present invention and a magnetic recording medium can be manufactured.
[Brief description of the drawings]
FIG. 1 is a schematic view of a recess formed on a substrate in the method for producing a nanostructure of the present invention.
FIG. 2 is a schematic view of pores branched in a self-organizing manner.
FIG. 3 is a schematic view of pores formed in unintended portions.
FIG. 4 is a schematic view of the formation of protrusions in the pores.
FIG. 5 is a schematic view of the formation of protrusions in the pores.
FIG. 6 is a schematic diagram of a convex structure with protrusions from an underlayer.
FIG. 7 is a schematic diagram of a convex structure with protrusions from a base layer and residual protrusions of the anodized layer.
FIG. 8 is a schematic diagram of a magnetic recording medium using a convex pattern according to the present invention.
FIG. 9 is a schematic diagram of a convex structure with residual protrusions of an Nb oxide and an anodized layer.
FIG. 10 is a schematic view of a state in which a protrusion is reinforced.
[Explanation of symbols]
11 Substrate
12 depressions
13 Short intervals between arrays
14 Long array spacing
21 Bifurcated pores
22 Fine pore before bifurcation
23 Alumina
24 Alumina remaining due to branching
25 Base substrate
26 Residual protrusion
27 Residual protrusion location
31 Pore formed in unintended part
32 Fine pores bifurcated
33 Fine pore before bifurcating
34 Alumina remaining due to branching
41 pores
42 Underlayer
43 Alumina
44 oxide
45 Residual protrusion
51 Underlayer
52 Anodized layer
53 pores
54 Projection
55 Residual protrusion
56 Alumina
61 Anodized layer
62 Alumina
63 Underlayer
64 Projection
65 Residual protrusion
66 pores
71 Underlayer
72 Projection
73 Anodized layer
74 Residual protrusion
75 Alumina
76 pores
81 Magnetic material
82 Projection
83 Recording part
84 Residual protrusion
85 Underlayer
91 Protrusion
92 Residual protrusion
93 Underlayer
101 Protrusion
102 Residual protrusion
103 Underlayer
104 tungsten

Claims (11)

In the method of manufacturing a structure that can include the step of anodizing a to- be-anodized film containing Al as a main component,
Preparing a member having the anodized film on the underlayer;
Forming a plurality of depressions regularly arranged on the anodized film;
The step of forming the pores branched toward the base layer by anodizing the anodic oxide film, using the depression as a starting point for pore formation,
Forming a protrusion on the foundation layer exposed at the bottom of the branched pores;
The manufacturing method of the structure characterized by including the process of removing the partition part of the said pore . The method of manufacturing a structure according to claim 1 , wherein the step of forming the protrusion is oxidation of the base layer. The method of manufacturing a structure according to claim 1 , wherein the step of forming the protrusion is plating. The method for manufacturing a structure according to any one of claims 1 to 3 , wherein the underlayer is a conductive metal. The method for manufacturing a structure according to any one of claims 1 to 4 , wherein the underlayer mainly contains any one of Nb, W, Ti, Ta, Mo, Zr, and Hf. The production method of anodic oxide film on a rectangular shape or structure according to any one of claims 1 to 5, characterized in that to form the recesses are arranged in oblique form. 7. The structure according to claim 6 , wherein depressions arranged in a rectangular shape or an oblique shape in which a long interval is 1.4 to 2.0 times a short interval are formed on the anodized film. Manufacturing method. Wherein the rectangular-shaped or oblique-shaped array of depressions formed on the anodic oxide film, according to claim 1 to 7, characterized in that the applied anodic oxidation anodization voltage corresponding to the short interval of sequence A method for producing the structure according to any one of the items. By removing the partition wall portion, claim 1 to 8, characterized in that to form the exposed convex structure due to residual protrusions composed mainly of protrusion thereof and Al formed from the base layer on a substrate A method for producing the structure according to any one of the above items. On a structure fabricated by, method of manufacturing the structure according to any one of claims 1 to 9, wherein depositing a different material with the structure. 10. The structure manufacturing method according to claim 1, wherein a magnetic material is deposited on the structure to be manufactured.

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