JP2007210086A - Nanohole structure and manufacturing method thereof, and magnetic recording medium and manufacturing method thereof - Google Patents

Abstract

A high-capacity recording and high-speed recording without increasing the write current of a magnetic head, a large capacity, excellent overwrite characteristics, uniform characteristics, and especially no problems such as cross-read and cross-write. Providing extremely high quality magnetic recording media.
A nanohole structure according to the present invention is characterized in that a nanohole array in which nanoholes are arranged one-dimensionally is paired at a predetermined interval on a metal substrate to form a nanohole array pair. The magnetic recording body of the present invention has a porous layer having a plurality of nanoholes formed in a direction substantially orthogonal to the substrate surface on a substrate, and has a magnetic material inside the nanoholes. The porous layer is the nanohole structure of the present invention.
[Selection] Figure 9D

Description

  The present invention is suitable for a nanohole structure suitable for a magnetic recording medium or the like and an efficient manufacturing method thereof, an external storage device for a computer, a hard disk device widely used as a consumer video recording device, etc. The present invention relates to a magnetic recording medium capable of high-capacity and high-speed recording and an efficient and low-cost manufacturing method thereof.

  In recent years, with technological innovation in the IT industry and the like, research and development for increasing the capacity, speed, and cost of magnetic recording media has been actively conducted. In order to increase the capacity, speed, and cost of the magnetic recording medium, it is essential to improve the recording density of the magnetic recording medium. Conventionally, attempts have been made to improve the recording density of the magnetic recording medium by horizontal recording of the continuous magnetic film in the magnetic recording medium, but the technical limit is approaching. The reason for this is that, if the crystal grains of the magnetic particles forming the continuous magnetic film are large, complex magnetic domains are generated and noise increases. This is because the magnetization decreases with time and an error occurs. Second, when the recording density of the magnetic recording medium is increased, the recording demagnetizing field is relatively increased. Therefore, it is necessary to increase the coercive force of the magnetic recording medium. This is because the write characteristics cannot be secured.

  Recently, research on a new recording method replacing the horizontal recording has been actively conducted. One is that the magnetic film in the magnetic recording medium is not a continuous film, but a pattern such as dots, bars, pillars, etc., and by making the size nanometer scale, the patterned film has a single magnetic domain structure instead of a complex magnetic domain. This is a recording method using media (see, for example, Non-Patent Document 1). The other is perpendicular recording, in which the recording demagnetizing field is small compared to the horizontal recording, so that the recording density can be increased and the recording layer need not be made extremely thin, so that the resistance against thermal fluctuation of the recording magnetization can be improved. (For example, refer to Patent Document 1). As for the recording method by the perpendicular recording, a proposal has been made to use a soft magnetic film and a perpendicular magnetization film in combination (for example, refer to Patent Document 2). There have been further proposals for forming a soft magnetic underlayer (see, for example, Patent Document 3). As an example of performing magnetic recording on a magnetic recording medium by the recording method by the perpendicular recording, as shown in FIG. 1, the main magnetic pole 102 of a writing / reading head (single pole head) 100 of the perpendicular magnetic recording method. Is opposed to the recording layer 30 of the magnetic recording medium. The magnetic recording medium has a soft magnetic layer 10, an intermediate layer (nonmagnetic layer) 20, and a recording layer (perpendicular magnetization film) 30 in this order on a substrate. A recording magnetic field input with a high magnetic flux density from the main magnetic pole 102 of the writing / reading head (single magnetic pole head) 100 to the recording layer (perpendicular magnetization film) 30 side is soft magnetic from the recording layer (perpendicular magnetization film) 30. The layer 10 flows from the soft magnetic layer 10 to the latter half 104 of the write / read head 100 (write and read head), and a magnetic circuit is formed. The portion facing the recording layer (perpendicular magnetization film) 30 in the latter half 104 is formed in a large area, so there is no influence of magnetization on the recording layer (perpendicular magnetization film) 30. The soft magnetic layer 10 in the magnetic recording medium also has a function of a writing / reading head (single pole head) 100.

  However, in this case, the recording layer (perpendicular magnetization film) 30 is applied to the soft magnetic layer 10 in addition to the recording magnetic field input from the writing / reading head (single magnetic pole head) 100 to the stray magnetic field leaking from the outside. However, there is a problem that recording noise increases due to concentration and magnetization. On the other hand, when the above-described magnetic film is formed into a pattern, the patterning is not easy and there is a problem such as high cost. On the other hand, when forming the above-mentioned soft magnetic underlayer, the distance between the single pole head and the soft magnetic underlayer during magnetic recording must be shortened, and if the distance is large, As shown in FIG. 2A, the magnetic flux from the writing / reading head (single pole head) 100 toward the soft magnetic underlayer diverges with distance, and the recording layer (perpendicular magnetization film) provided on the soft magnetic layer 10 There is a problem that only a large bit can be written in the lower part of 30 because only a recording with a spread magnetic field can be performed. In this case, the write current by the write / read head (single pole head) 100 must also be increased, and if a small bit is written after a large bit is written, the unerased large bit becomes large, There is a problem that the overwrite characteristic is deteriorated.

  Therefore, as a new magnetic recording medium that combines the recording method using the patterned medium and the recording method by the perpendicular recording, a magnetic recording medium in which a pore of an anodized alumina pore is filled with a magnetic metal has also been proposed. (For example, refer to Patent Document 4). As shown in FIG. 3, the magnetic recording medium has a base electrode layer 120 and an anodized alumina layer 130 in this order on a substrate 110, and a large number of alumina pores are ordered in the anodized alumina layer 130. A ferromagnetic layer 140 is formed by filling the alumina pores with a ferromagnetic metal.

However, in this case, in order to form the ordered alumina pores in the anodized alumina layer 130, the anodized alumina layer 130 having a thickness exceeding 500 nm is usually required. Even if the soft magnetic underlayer is provided, the density is high. There is a problem that recording cannot be performed. For this reason, it has been studied to reduce the thickness by polishing the anodized alumina layer 130, but the polishing is not easy, takes time, is expensive, and causes quality deterioration. . Actually, in order to perform magnetic recording at a linear recording density of 1,500 kBPI targeting 1 Tb / in ² , the distance between the single pole head and the soft magnetic underlayer is set to about 25 nm, and the anodized alumina layer 130 is used. Therefore, it is necessary to make the thickness of the anodized alumina layer 130 a problem of polishing.

  Note that the magnetic recording medium in which the magnetic material is filled in the anodic alumina pores is magnetized in the vertical direction because the anodic alumina pores are elongated in the direction perpendicular to the exposed surface (with a high aspect ratio). The shape anisotropy of the filled magnetic material is advantageous because it is resistant to thermal fluctuations. In addition, since the anodized alumina pores are normally generated in a honeycomb-type hexagonal close-packed lattice in a self-organized manner, it can be manufactured at a lower cost than a method of forming dots one by one by lithography. There are advantages.

  However, since the anodized alumina pores are two-dimensionally arrayed, such as a hexagonal close-packed lattice, from the viewpoint of magnetic recording, it is impossible to provide a gap between adjacent bit strings. There is. That is, in the patterned medium, it is ideal to record 1 bit per dot, but since dots exist in the radial direction at the same pitch as the linear direction (circumferential direction) There is a fatal problem that a cross light or a croread is generated. Therefore, for example, as shown in FIGS. 4A and 4B, one bit (63 in FIG. 4B) must be changed from several to several tens or more dots (61 in FIGS. 4A and 4B). However, even in this case, there still remains a problem that the cross write or cross read occurs. Therefore, a magnetic recording medium is desired in which the anodized alumina pores filled with a magnetic material are arranged in a row and a nonmagnetic region is provided between the rows.

  On the other hand, a proposal has also been made in which a concavo-convex pattern is provided on a substrate and a pattern of a patterned medium is arranged along a groove (for example, see Patent Documents 5 and 6). In these cases, the block copolymer and fine particles are two-dimensionally arranged in the groove part in a self-organized manner, and the magnetic material is embedded using this two-dimensional pattern, but the pores are arranged in a line on one track. It cannot be aligned. In addition, the method of forming an aluminum band structure in the groove and anodizing this to form a fine nanohole array in a self-organized manner is also mentioned. This also involves a row of anodized alumina pores on a straight line of one track. Cannot be aligned.

  On the other hand, a patterned medium is also proposed in which a magnetic material pattern is formed in a line shape using electron beam lithography or near-field light lithography (see, for example, Patent Document 7). In this case, it is possible in principle to align dots on a single line of track using a pattern drawing device, and after processes such as etching and ion milling for magnetic dot formation are necessary after pattern formation. Further, there is a problem that the magnetic material is limited because it is necessary to provide anisotropy in the vertical direction for perpendicular recording, and a process such as a heat treatment is required, resulting in an increase in cost. Also, as the pattern size becomes as fine as the nm order, it takes a long time to draw a dot pattern over the entire surface of the disk, resulting in an increase in cost due to poor throughput. It is very difficult to keep the intensity of the field light and the focus state stable, and there is a problem that the yield decreases due to the generation of defects due to destabilization, leading to an increase in cost.

S. Y. Chou Proc. IEEE 85 (4), 652 (1997) Japanese Patent Laid-Open No. 6-180834 JP-A-52-134706 JP 2001-283419 A JP 2002-175621 A JP 2003-109333 A JP 2003-157503 A JP 2002-298448 A

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, it is widely used as a nanohole structure suitable for various fields such as magnetic recording media, DNA chips, catalyst substrates, etc., and its efficient manufacturing method, as well as external storage devices for computers, consumer video recording devices, etc. It is suitable for hard disk drives, etc., which can perform high-density recording and high-speed recording without increasing the write current of the magnetic head, has a large capacity, has excellent overwrite characteristics, and has uniform characteristics. An object of the present invention is to provide an extremely high-quality magnetic recording medium free from problems such as writing, and an efficient and low-cost manufacturing method thereof.

As a result of intensive studies, the present inventors have realized the recording / reproduction of 1 dot and 1 bit by arranging the alumina pores in one row and forming a nonmagnetic region between the alumina pore rows made of the alumina pores. I found it possible. Then, in a vertical patterned medium using anodized alumina pores, the anodized alumina pores are aligned in one row, and a plurality of alumina pore rows made of the anodized alumina pores are connected to each other through a region where the anodized alumina pores are not present. The inventors invented a magnetic recording medium obtained by arranging and filling a magnetic material in the pores of the anodized alumina pores, a method for manufacturing the same, and the like. Specifically, as shown in FIG. 6A, a mold having a 150 nm pitch line / space pattern is pressed against the aluminum layer that is anodized to form alumina pores, and the surface of the aluminum layer is pressed. A line (concave portion or groove portion) / space (convex portion or land portion) pattern is imprinted to form a straight concavo-convex pattern (in which concave lines are arranged at regular intervals). Next, when anodizing is performed in diluted oxalic acid at a voltage of 60 V, as shown in FIG. 6B, alumina pores are self-organized only in the concave line (groove portion) and in the length direction thereof. On the other hand, the alumina pores were not formed at all on the convex portion, while being formed in an array. Then, by filling the alumina pores in these alumina pore rows with a magnetic material, a magnetic recording medium capable of recording / reproducing 1 dot / 1 bit was obtained.
However, as shown in FIG. 6B, only one row of alumina pores is formed in one concave line (groove portion), and in order to form the alumina pores at a higher density, the surface of the aluminum layer is previously formed. The pitch of the linear concavo-convex pattern to be formed must be made fine. For example, in the current EB exposure technology, it is the limit to form a concavo-convex pattern with a pitch of 100 to 50 nm. The density of alumina pores is increased, and a magnetic recording medium (magnetic disk) filled with a magnetic material in the alumina pores. ) Is difficult to achieve.
Therefore, the present inventors obtained the following knowledge as a result of further studies. That is, when forming an alumina pore by anodizing, by optimizing the conditions of the anodizing, the alumina pore is self-organized only in the concave line (groove portion) and in the length direction thereof. This is a finding that two rows can be arranged.

The present invention is based on the above findings of the present inventors, and means for solving the above-described problems are as listed in the appendix described later. That is,
The nanohole structure of the present invention is characterized in that a nanohole array in which nanoholes are arranged one-dimensionally is paired at a predetermined interval on a metal substrate to form a nanohole array pair (nanohole array pair).
The nanohole structure can be used as a magnetic recording medium such as a hard disk device if the nanohole is filled with a magnetic material, and can be used as a DNA chip if DNA or the like is arranged in the nanohole. If the nanohole is provided with an antibody or the like, a protein detection device, a diagnostic device, or the like can be formed. If the nanohole is filled with a catalyst metal such as for forming a carbon nanotube, formation of a carbon nanotube or the like is possible. It can be a substrate, a field emission device or the like.

In the method for producing a nanohole structure of the present invention, a groove portion and a land portion are formed on a metal substrate, and then anodized at a voltage given by either of the following formula (1) and the following formula (2). And a nanohole formation processing step for forming a nanohole array pair.
Groove width (nm) / A (nm / V) (1)
Groove width (nm) / (√3 / 2) / A (nm / V) (2)
However, in said Formula (1) and said Formula (2), A is 2.0-3.0.
In the nanohole structure manufacturing method, since the anodizing process is performed at the voltage given by either of the formula (1) and the formula (2) in the nanohole forming process, the nanohole is formed in the groove portion. Column pairs are formed efficiently.

The magnetic recording medium of the present invention has a porous layer in which a plurality of nanoholes are formed in a direction substantially perpendicular to the substrate surface on a substrate, and has a magnetic material inside the nanoholes. The material layer is the nanohole structure of the present invention.
In the magnetic recording medium, nanohole arrays in which nanoholes filled with the magnetic material are one-dimensionally arranged are paired at regular intervals to form nanohole array pairs. It is capable of density recording and high-speed recording, has a large capacity, is excellent in overwrite characteristics, has uniform characteristics, has no problems such as cross-reading and cross-writing, and has extremely high quality. The magnetic recording medium is suitable for an external storage device of a computer, a hard disk device widely used as a consumer video recording device and the like.

The method for producing a magnetic recording medium of the present invention is a method for producing the magnetic recording medium of the present invention, wherein a metal layer is formed on a substrate, and then a groove portion and a land portion are formed on the metal layer. The nanohole structure is formed by forming a plurality of nanohole array pairs in a direction substantially orthogonal to the substrate surface by anodizing with a voltage given by either of the following formula (1) and the following formula (2): A nanohole structure forming step, and a magnetic material filling step of filling the nanohole in the nanohole array pair with a magnetic material.
Groove width (nm) / A (nm / V) (1)
Groove width (nm) / (√3 / 2) / A (nm / V) (2)
However, in said Formula (1) and said Formula (2), A is 2.0-3.0.
In the method of manufacturing the magnetic recording medium, in the nanohole structure forming step, after a metal layer is formed on the substrate, a groove portion and a land portion are formed in the metal layer, and the formula (1) and the Anodization is performed at a voltage given by any one of the formulas (2), and a plurality of nanohole array pairs are formed in a direction substantially orthogonal to the substrate surface to form a nanohole structure. In the magnetic material filling step, the magnetic material is filled into the nanoholes in the nanohole array. As a result, the magnetic recording medium of the present invention is manufactured.

A magnetic recording apparatus according to the present invention includes the magnetic recording medium according to the present invention and a perpendicular magnetic recording head. In the magnetic recording medium, since the perpendicular magnetic recording head performs recording on the magnetic recording medium, the magnetic recording medium can perform high-density recording and high-speed recording without increasing the write current of the magnetic head. It has a large capacity, excellent overwrite characteristics, uniform characteristics, no problems such as cross read and cross write, and extremely high quality.
The magnetic recording medium particularly has a soft magnetic layer and a ferromagnetic layer in this order from the substrate side inside the nanohole, and the thickness of the ferromagnetic layer is equal to or less than the thickness of the soft magnetic layer. When the magnetic recording medium is subjected to magnetic recording using the perpendicular magnetic recording head such as a single magnetic pole head, the distance between the perpendicular magnetic recording head and the soft magnetic layer is the porous layer. Therefore, the magnetic flux concentration from the perpendicular magnetic recording head is used only by the thickness of the ferromagnetic layer regardless of the thickness of the porous layer. It is possible to control the optimum magnetic recording / reproducing characteristics at a recording density. In this case, as shown in FIG. 2B and FIG. 5, the magnetic flux from the single magnetic pole head (write / read head 100) is concentrated on the ferromagnetic layer (perpendicular magnetization film) 30. As compared with the above, the writing efficiency is greatly improved, the writing current is small, and the overwrite characteristic is remarkably improved.

The magnetic recording method of the present invention includes performing recording on the magnetic recording medium of the present invention using a perpendicular magnetic recording head. In the magnetic recording method, since the perpendicular magnetic recording head performs recording on the magnetic recording medium, the magnetic recording medium can perform high-density recording and high-speed recording without increasing the write current of the magnetic head. It has a large capacity, excellent overwrite characteristics, uniform characteristics, and there are no problems such as cross read and cross write.
The magnetic recording medium particularly has a soft magnetic layer and a ferromagnetic layer in this order from the substrate side inside the nanohole, and the thickness of the ferromagnetic layer is equal to or less than the thickness of the soft magnetic layer. When the magnetic recording medium is subjected to magnetic recording using the perpendicular magnetic recording head such as a single magnetic pole head, the distance between the perpendicular magnetic recording head and the soft magnetic layer is the porous layer. Therefore, the magnetic flux concentration from the perpendicular magnetic recording head is used only by the thickness of the ferromagnetic layer regardless of the thickness of the porous layer. It is possible to control the optimum magnetic recording / reproducing characteristics at a recording density. In this case, as shown in FIG. 2B and FIG. 5, the magnetic flux from the single magnetic pole head (write / read head 100) is concentrated on the ferromagnetic layer (perpendicular magnetization film) 30. As compared with the above, the writing efficiency is greatly improved, the writing current is small, and the overwrite characteristic is remarkably improved.

  According to the present invention, conventional problems can be solved, and a nanohole structure suitable for various fields such as a magnetic recording medium, a DNA chip, and a catalyst substrate, an efficient manufacturing method thereof, and an external storage of a computer Suitable for hard disk drives that are widely used as video recorders and consumer video recorders, etc., capable of high-density recording and high-speed recording without increasing the write current of the magnetic head, high capacity, and excellent overwrite characteristics Therefore, it is possible to provide an extremely high quality magnetic recording medium having a uniform characteristic and having no problems such as cross read and cross write, and an efficient and low cost manufacturing method thereof.

(Nanohole structure)
The nanohole structure of the present invention is not particularly limited, except that a nanohole array in which nanoholes are arranged one-dimensionally is paired at regular intervals to form a nanohole array pair (nanohole array pair) on a metal substrate. The material, shape, structure, size, etc. can be appropriately selected according to the purpose.

  The material for the metal substrate is not particularly limited and may be appropriately selected depending on the purpose, and may be any of a simple metal, an oxide thereof, a nitride, an alloy, etc. Among them, for example, Particularly preferred are alumina (aluminum oxide), aluminum, glass, silicon and the like.

There is no restriction | limiting in particular as said shape, According to the objective, it can select suitably, For example, plate shape, disk shape (disk shape), etc. are mentioned suitably. Among these, when the nanohole structure is applied to a magnetic recording medium such as a hard disk, a disk shape (disk shape) is preferable.
In addition, when the said shape is the said plate shape, disk shape, etc., the said nanohole (pore) is formed in the direction substantially orthogonal to these one exposed surface (plate surface).
The nanohole may be formed as a hole penetrating the nanohole structure, or may be formed as a hole (dent) without penetrating the nanohole structure. For example, the nanohole structure Is used as the magnetic recording medium, the nanohole is preferably formed as a through hole penetrating the nanohole structure.

There is no restriction | limiting in particular as said structure, Although it can select suitably according to the objective, For example, a single layer structure may be sufficient and a laminated structure may be sufficient.
The size is not particularly limited and can be appropriately selected according to the purpose. For example, when the nanohole structure is applied to a magnetic recording medium such as a hard disk, the size of an existing hard disk or the like is not limited. When the nanohole structure is applied to a DNA chip or the like, the size corresponding to the size of an existing DNA chip or the like is preferable, and the nanohole structure is preferably a carbon for a field emission device. When applied to a catalyst substrate such as a nanotube, a size corresponding to the field emission device is preferable.

The arrangement of the nanohole array pairs is not particularly limited and may be appropriately selected depending on the purpose.For example, the nanohole array pairs may be arranged in parallel in one direction, or at least one of concentric and spiral shapes. It may be arranged. The former arrangement is preferable when the nanohole structure is applied to a DNA chip or the like, and the latter arrangement is preferable when the nanohole structure is applied to the magnetic recording medium such as a hard disk or a video disk. In the case of use, a concentric shape is preferable from the viewpoint of easy access, and in the case of video disk use, a spiral shape is preferable from the viewpoint of easy continuous reproduction.
When the nanohole structure is suitable for the magnetic recording medium such as a hard disk, it is preferable that the nanoholes in adjacent nanohole array pairs are arranged in the radial direction. In this case, the magnetic recording medium is capable of high-density recording and high-speed recording without increasing the write current of the magnetic head, has a large capacity, has excellent overwrite characteristics, and has uniform characteristics. There is no problem of light etc. and it is extremely high quality.

The nanohole structure preferably has a concavo-convex line in which groove portions and land portions are alternately arranged, and the nanohole row pair is preferably formed only in the groove portion. In this case, the nanohole row pairs are separated at the land portions and regularly arranged at regular intervals. In addition, the said groove part means the part which has a concave shape with respect to the surface of the said metal base material, and the said land part means the part which has a convex shape with respect to the said groove part.
There is no restriction | limiting in particular as a formation method of the uneven | corrugated line which consists of the said groove part and the said land part, According to the objective, it can select suitably, For example, it can carry out by formation of the concave line mentioned later.

  The spacing between the nanohole rows in which the nanoholes are one-dimensionally arranged in the nanohole row pair is not particularly limited and may be appropriately selected according to the purpose. The plurality of nanoholes arranged in each nanohole row The distance between imaginary lines connecting the center points in FIG. 8 (X in FIGS. 8A and 8B) is given by the width of the groove portion formed by forming a concave line to be described later, and the anode forming the nanohole array It is only necessary that the voltage in the oxidation treatment satisfies formula (1) or formula (2) described later.

The interval between the nanohole column pairs is not particularly limited and can be appropriately selected according to the purpose. For example, the interval between nanohole columns in one nanohole column pair is the same as that of the one nanohole column pair. The distance between the nanohole array pair and the adjacent nanohole array pair is substantially the same (in the adjacent nanohole array pair, the interval between the nanohole arrays located inside, that is, arranged in each nanohole array located inside The distance between virtual lines connecting the center points in the plurality of nanoholes (Y in FIGS. 8A and 8B) is the distance between virtual lines connecting the center points in the plurality of nanoholes arranged in each nanohole row ( 8A and 8B), the nanohole structure is formed in such a manner that all the nanohole rows are arranged at substantially equal intervals. It can be suitably used in the magnetic recording medium such as a hard disk.
On the other hand, when the Y is larger than the X and less than twice the X, preferably not more than 1.8 times, the distance between the adjacent nanohole row pairs is a pair in the nanohole row pair. This is preferable in that it is wider than the distance (interval) between the two nanohole rows, and the nanohole pairs can be separated from each other. In this case, when the nanohole structure is applied to a magnetic disk, cross-write and cross-read between the nanohole pairs can be reduced. Further, a different function can be imparted to each nanohole array in the array pattern. For example, for each nanohole array, a DNA chip in which different DNA is arranged in the nanohole in the nanohole array, It can be used for a protein detection apparatus provided with an antibody or the like.

In the nanohole array pair, the ratio (interval / width) between the interval between the one-dimensionally arranged nanohole arrays and the width of the nanohole array (Y / X in terms of X and Y in FIGS. There is no restriction | limiting in particular, Although it can select suitably according to the objective, For example, 1.0 or more and less than 2 are preferable and 1.0-1.8 are more preferable.
If the ratio (interval / width) is less than 1.0, adjacent nanoholes may be fused together, so that independent nanoholes may not be obtained. Nanoholes may also be formed in portions other than the groove portion (concave line portion) during anodization described later, and it is difficult to form a regular arrangement of nanoholes.

In the nanohole array pair, the values of the interval between the nanohole arrays in which the nanoholes are one-dimensionally arranged (Y in FIGS. 8A and 8B) and the width of the nanohole array (X in FIGS. 8A and B) are particularly limited. However, for example, when the nanohole structure is suitable for the magnetic recording medium such as a hard disk, the smaller one is preferable for increasing the density. When Y = 25 nm, a recording density of 1 Tbit / in ² is possible.

The opening diameter in the nanohole is not particularly limited and may be appropriately selected depending on the intended purpose.For example, when the nanohole structure is applied to a magnetic recording medium such as a hard disk, the ferromagnetic layer has a single magnetic domain. In particular, it is preferably 100 nm or less, and preferably 30 nm or less, and more preferably 5 to 20 nm from the viewpoint of realizing high-density recording.
When the aperture diameter in the nanohole exceeds 100 nm, the magnetic recording medium to which the nanohole structure is applied may not have a single domain structure.

The aspect ratio (depth / opening diameter) between the depth and the opening diameter in the nanohole is not particularly limited and can be appropriately selected according to the purpose. It is preferable in that it can be increased and the holding power of the magnetic recording medium can be improved. For example, when the nanohole structure is applied to a magnetic recording medium such as a hard disk, the number is preferably 2 or more, and 3 to 15 Is more preferable.
If the aspect ratio is less than 2, the holding power of the magnetic recording medium may not be sufficiently improved.

The thickness of the nanohole structure is not particularly limited and may be appropriately selected depending on the intended purpose. For example, when the nanohole structure is applied to a magnetic recording medium such as a hard disk, the thickness is preferably 500 nm or less, and 300 nm. The following is more preferable, and 20 to 200 nm is particularly preferable.
When the thickness of the nanohole structure exceeds 500 nm, when the nanohole structure is applied to a magnetic recording medium such as a hard disk, high-density recording is performed even if the soft magnetic underlayer is provided on the magnetic recording medium. In some cases, it is necessary to polish the nanohole structure. In this case, time is required and the cost is high, which may cause quality degradation.

  The nanohole structure of the present invention can be suitably used in various fields such as a magnetic recording medium, a DNA chip, a catalyst substrate, and the like. It can be suitably used for a hard disk device or the like widely used as an external storage device or a consumer video recording device.

(Manufacturing method of nanohole structure)
The method for producing a nanohole structure according to the present invention is a method for producing the nanohole structure according to the present invention, which includes at least a nanohole formation treatment step, and further includes other steps appropriately selected as necessary.

<Nanohole formation process>
The nanohole forming treatment step is a step of forming nanohole array pairs by forming a groove portion and a land portion on a metal substrate and then performing anodization treatment.
The details of the metal substrate, the nanohole array pair, and the like are as described above in the description of the nanohole structure.

  The formation of the metal substrate is not particularly limited and can be performed according to a known method. For example, the metal substrate can be formed by forming a metal material layer by a sputtering method, a vapor deposition method, or the like.

  The said groove part means the part which has a concave shape with respect to the surface of the said metal base material. On the other hand, the land portion means a portion having a convex shape with respect to the groove portion. There is no restriction | limiting in particular as a formation aspect in the surface of these said metal base materials, Although it can select suitably according to the objective, It is a line shape parallel with respect to the specific side in the said metal base material. An embodiment in which a plurality of the groove portions and the land portions are alternately arranged is preferable. In this case, an uneven line is formed by the groove part and the land part, and the nanohole row pair can be formed only on the concave line (the groove part) via the convex line (the land part).

  The formation of the groove portion and the land portion is not particularly limited and can be performed according to a known method, but is preferably performed by forming a concave line on the metal substrate. In this case, the concave line (recessed part) formed on the metal base corresponds to the groove part, and the convex line (part excluding the concave line) on the metal base corresponds to the land part. . And the said nanohole row | line | column pair can be efficiently formed only on the said concave line (groove part).

  The width of the groove portion and the land portion is not particularly limited and can be appropriately selected according to the purpose. The width of the land portion (Y in FIG. 8A) is the width of the groove portion (FIG. 8A). It is preferably larger than X) and less than 2 times, more preferably 1.8 times or less. When the widths of the groove part and the land part satisfy the numerical range, the distance between one nanohole array and the nanohole array pair adjacent to the one nanohole array pair is a pair in the one nanohole array pair. Thus, the distance (interval) between the two nanohole arrays becomes wider, and the nanohole pairs can be separated from each other. In this case, when the nanohole structure is applied to a magnetic disk, cross-write and cross-read between the nanohole pairs can be reduced. Further, a different function can be imparted to each nanohole array in the array pattern. For example, for each nanohole array, a DNA chip in which different DNA is arranged in the nanohole in the nanohole array, It can be used for a protein detection apparatus provided with an antibody or the like.

Further, the width of the groove portion may be changed (wide or narrow) at regular intervals (constant period) in the length direction. In this case, as shown in FIGS. 7A and 7B, the nanoholes are easily formed in a portion where the width of the groove portion is wide, so that the arrangement state of the nanoholes in the nanohole array pair can be changed.
For example, as shown in FIG. 7A, when the width of the groove portion is formed in a wave shape widened at regular intervals (constant period) in the length direction, two nanoholes are formed in the wide portion of the groove portion. Therefore, the nanohole array pair in which the nanoholes are arranged in a square lattice shape can be formed. Furthermore, for example, as shown in FIG. 7B, when the width of the wavy groove portion is formed by shifting the width of the groove portion by half a period, the nanoholes are formed in the wide portion of the groove portion, At this time, since the arrangement interval of the nanoholes is shifted by a half cycle for each nanohole row, the nanohole row pair in which the nanoholes are arranged in a triangular lattice shape can be formed. In addition, since the nanohole is formed more stably in the triangular lattice arrangement than in the square lattice arrangement, the triangular lattice arrangement can be formed when the square lattice arrangement is disturbed. It is preferable to form the groove portion.

  The method for forming the concave line is not particularly limited and may be appropriately selected depending on the intended purpose. For example, (1) convex lines (nanoholes) in which convex lines and spaces are arranged at regular intervals When the structure is applied to a magnetic disk or the like, a mold having a concentric or spiral convex line) as a surface shape (a disk-shaped mold when the nanohole structure is applied to a magnetic disk or the like) is used. A method of imprint transfer onto the surface of the metal layer (for example, alumina, aluminum, etc.) to form a concave line in which concave lines and spaces are arranged at regular intervals, and (2) a resin layer on the metal layer And a method of forming a concave line on the surface of the metal layer by patterning and etching the layer after forming a photoresist layer, and (3) before Directly on the metal layer, a method of forming a groove (concave lines), and the like.

At this time, by changing the width of the convex line in the mold, the width of the concave line pattern formed in the photoresist layer, etc. at regular intervals (constant period) in the length direction, the nanohole array The arrangement state of the nanoholes in the pair can be changed, and can be aligned with higher density. In this case, it is preferable to apply the nanohole structure to a magnetic recording medium in that the jitter is reduced and high-density recording is possible.
Moreover, it is preferable that the said concave line is divided | segmented at the fixed space | interval in the length direction. In this case, it is advantageous in that the nanoholes can be arrayed at substantially constant intervals in the divided concave lines.

  There is no restriction | limiting in particular as said mold, Although it can select suitably according to the objective, From a viewpoint of continuous use durability, a silicon carbide substrate etc. are mentioned, Moreover, it is used for the shaping | molding of an optical disk, etc. Ni stamper etc. are also mentioned. The mold can be used multiple times. There is no restriction | limiting in particular as the method of the said imprint transfer, According to the objective, it can select suitably from well-known methods. The resist material for the photoresist layer includes not only a photoresist material but also an electron beam resist material. There is no restriction | limiting in particular as said photoresist material, It can select suitably from well-known materials in the semiconductor field | area etc., For example, the material etc. which can utilize near ultraviolet light, near-field light, etc. are mentioned.

Moreover, as the voltage in the anodizing treatment, it is necessary to select a voltage having a value given by either of the following formula (1) and the following formula (2).
Groove width (nm) / A (nm / V) (1)
Groove width (nm) / (√3 / 2) / A (nm / V) (2)
However, in said Formula (1) and said Formula (2), A is 2.0-3.0, 2.5 +/- 0.2 is preferable and 2.5 is especially preferable. When the A is in the range of 2.0 to 3.0, the nanohole array pair can be formed in the groove portion.

  When the voltage is a value selected from the range given by either the formula (1) or the formula (2), the nanohole array pair can be formed only on the groove portion. It is advantageous. Further, when the anodization treatment is performed at a voltage selected from the range given by the formula (1), as shown in FIG. 8A, nanohole array pairs in which the nanoholes are arranged in a triangular lattice can be formed. When the anodizing treatment is performed at a voltage selected from the range given by Equation (2), a nanohole array pair in which the nanoholes are arranged in a square lattice can be formed as shown in FIG. 8B.

  In addition, there is no restriction | limiting in particular as a kind, density | concentration, temperature, time, etc. of the electrolyte solution in the said anodizing process, According to the number of nanoholes to form, a magnitude | size, an aspect-ratio, etc., it can select suitably. For example, as the kind of the electrolytic solution, when the interval (pitch) between the adjacent nanohole rows is 150 to 500 nm, a diluted phosphoric acid solution is preferable, and when it is 80 to 200 nm, diluted oxalic acid is used. A solution is mentioned suitably, When it is 10-150 nm, a dilute sulfuric acid solution is mentioned suitably. In any case, the adjustment of the aspect ratio of the nanohole can be performed by increasing the diameter of the nanohole (alumina pore) by immersing in a phosphoric acid solution after the anodizing treatment.

Through the above-described steps, a nanohole structure in which nanohole arrays in which the nanoholes are one-dimensionally arranged are paired at regular intervals to form nanohole array pairs on the metal substrate is manufactured.
Hereinafter, an example of a method for producing a nanohole structure according to the present invention will be described with reference to the drawings.
First, as shown in FIG. 9A, a mold 54 having a line / space pattern is placed on a metal substrate (for example, an aluminum layer) 52 that is anodized to form nanoholes (alumina pores). Next, as shown in FIG. 9B, a mold 54 is pressed against the metal base 52, and as shown in FIG. 9C, a plurality of groove portions (concave lines) G and land portions ( An uneven pattern 56 in which convex lines (L) are alternately arranged is imprinted. Next, anodizing treatment is performed in diluted sulfuric acid at a voltage selected from the numerical range given by either of the formula (1) and the formula (2). Then, as shown in FIG. 9D, only in the groove portion G, nanohole row pairs 58 in which nanohole rows 58A in which nanoholes (alumina pores) 58a are regularly arranged one-dimensionally are arranged in pairs at regular intervals are formed. The above is the nanohole forming process. As a result, the nanohole structure of the present invention is manufactured.

  According to the method for producing a nanohole structure of the present invention, a series of nanoholes in which the nanoholes are regularly arranged in a one-dimensional manner in a self-organized manner only in the groove portion and in the length direction thereof are paired at regular intervals. Since the formed nanohole array pair can be formed, the nanohole structure of the present invention in which nanoholes are regularly formed at a higher density can be efficiently produced.

(Magnetic recording medium)
The magnetic recording medium of the present invention has a porous layer on a substrate, and further has other layers appropriately selected as necessary.

Examples of the porous layer include those in which a plurality of nanoholes are formed in a direction substantially orthogonal to the substrate surface, and the nanohole structure is preferable. The details of the nanohole structure are as described above.
There is no restriction | limiting in particular as thickness of the said porous layer, Although it can select suitably according to the objective, For example, 500 nm or less is preferable and 5-200 nm is more preferable.
When the thickness of the porous layer exceeds 500 nm, it may be difficult to fill the nanohole with the magnetic material.

  The nanohole in the porous layer (nanohole structure) may be formed as a through hole through the porous layer or may be formed as a hole without penetrating, but the nanohole is magnetic. In consideration of a case where a magnetic layer is formed by filling a material and a magnetic layer is further formed thereunder, the nanoholes are preferably formed as through holes.

The nanohole is preferably filled with a magnetic material to form a magnetic layer.
There is no restriction | limiting in particular as said magnetic layer, Although it can select suitably according to the objective, For example, a ferromagnetic layer, a soft magnetic layer, etc. are mentioned. In the present invention, the soft magnetic layer and the ferromagnetic layer are laminated in this order from the substrate side inside the nanohole, and a nonmagnetic layer (intermediate layer) is formed as necessary. Is preferred.

The shape, structure, size, material and the like of the substrate are not particularly limited and can be appropriately selected according to the purpose. For example, the shape of the substrate is a magnetic disk such as a hard disk. In this case, the structure is a disk, and the structure may be a single layer structure or a laminated structure, and the material may be a base material of a magnetic recording medium. The material can be appropriately selected from known materials, and examples thereof include aluminum, glass, silicon, quartz, and SiO ₂ / Si formed by forming a thermal oxide film on the silicon surface. These board | substrate materials may be used individually by 1 type, and may use 2 or more types together.
In addition, the said board | substrate may be manufactured suitably and a commercial item may be used.

The ferromagnetic layer functions as a recording layer in the magnetic recording medium and constitutes a magnetic layer together with the soft magnetic layer.
The material of the ferromagnetic layer is not particularly limited and may be appropriately selected from known materials according to the purpose. For example, Fe, Co, Ni, FeCo, FeNi, CoNi, CoNiP, FePt, CoPt And at least one selected from NiPt are preferred. These may be used individually by 1 type and may use 2 or more types together.
The ferromagnetic layer is not particularly limited as long as it is formed as a perpendicular magnetization film by the material, can be appropriately selected depending on the intended purpose, for example, a Ll ₀ ordered structure, wherein the C-axis substrate And those having an fcc structure or a bcc structure and having the C-axis aligned in the direction perpendicular to the substrate.

The thickness of the ferromagnetic layer is not particularly limited as long as the effect of the present invention is not impaired, and can be appropriately selected according to the linear recording density used at the time of recording. For example, (1) the soft magnetism An aspect that is equal to or less than the thickness of the layer, (2) an aspect that is 1/3 to 3 times the minimum bit length determined by the linear recording density used during recording, and (3) the soft magnetic layer and the soft magnetic underlayer For example, in the case where magnetic recording is performed at a linear recording density of 1,500 kBPI targeting 1 Tb / in ² , typically, about 5 to 100 nm is preferable, and 5 to 50 nm is more preferable. Is preferably 50 nm or less (about 20 nm).
Here, the thickness of the “ferromagnetic layer” is such that the ferromagnetic layer is a laminated structure or a structure divided into a plurality of layers (for example, a continuous layer divided by an intermediate layer such as a nonmagnetic layer). (Non-structure) means the total thickness of each ferromagnetic layer. Further, the thickness of the “soft magnetic layer” is such that the soft magnetic layer is a laminated structure or a structure divided into a plurality of layers (for example, a structure that is not divided into an intermediate layer such as a nonmagnetic layer to form a continuous layer) Means the total thickness of each soft magnetic layer. In addition, the “total thickness of the soft magnetic layer and the soft magnetic underlayer” refers to a structure in which at least one of the soft magnetic layer and the soft magnetic under layer is laminated or divided into a plurality of layers (for example, non- In the case of having a structure which is divided by an intermediate layer such as a magnetic layer and is not a continuous layer, it means the total thickness of each soft magnetic layer.

In the case of the magnetic recording medium of the present invention, the distance between the single magnetic pole head used for magnetic recording and the soft magnetic layer is shorter than the thickness of the porous layer and substantially equal to the thickness of the ferromagnetic layer. Therefore, regardless of the thickness of the porous layer, only the thickness of the ferromagnetic layer controls the concentration of magnetic flux from the single-pole head and the optimum magnetic recording / reproducing characteristics at the recording density used. It becomes possible. As a result, in the magnetic recording medium, compared with the conventional magnetic recording medium, the writing efficiency is greatly improved, the writing current is reduced, and the overwrite characteristic can be remarkably improved.
The formation of the ferromagnetic layer is not particularly limited and can be performed according to a known method. For example, it can be performed by electrodeposition (electrodeposition method) or the like.

  The soft magnetic layer is not particularly limited and may be appropriately selected from known materials according to the purpose. For example, at least one selected from NiFe, FeSiAl, FeC, FeCoB, FeCoNiB and CoZrNb, Etc. are preferable. These may be used individually by 1 type and may use 2 or more types together.

  The thickness of the soft magnetic layer is not particularly limited as long as the effects of the present invention are not impaired, and can be appropriately selected according to the depth of the nanoholes in the porous layer, the thickness of the ferromagnetic layer, and the like. Examples include (1) an aspect in which the thickness of the ferromagnetic layer exceeds the thickness, and (2) an aspect in which the sum of the thickness of the soft magnetic underlayer exceeds the thickness of the ferromagnetic layer.

The soft magnetic layer is advantageous in that the magnetic flux from the magnetic head used for magnetic recording can be effectively converged on the ferromagnetic layer, and the perpendicular component of the magnetic field of the magnetic head can be increased. . Preferably, the soft magnetic layer can form a magnetic circuit of a recording magnetic field input from the magnetic head together with the magnetic head together with the soft magnetic underlayer.
The soft magnetic layer preferably has an easy magnetization axis in a direction substantially perpendicular to the substrate surface. In this case, when recording is performed with the perpendicular magnetic recording head, the concentration of magnetic flux from the perpendicular magnetic recording head, the optimum magnetic recording / reproducing characteristics at the recording density to be used, and the like can be controlled. As a result of concentrating on the layers, the write efficiency is greatly improved, the write current is reduced, and the overwrite characteristics are remarkably improved as compared with the conventional magnetic recording apparatus.
The formation of the soft magnetic layer is not particularly limited and can be performed according to a known method. For example, it can be performed by electrodeposition (electrodeposition method) or the like.

The nanohole in the porous layer may have a nonmagnetic layer (intermediate layer) between the ferromagnetic layer and the soft magnetic layer. If the non-magnetic layer (intermediate layer) is present, the effect of the exchange coupling force between the ferromagnetic layer and the soft magnetic layer is weakened. Can be controlled to a desired reproduction characteristic.
The material of the nonmagnetic layer is not particularly limited and can be appropriately selected from known materials. For example, the material is selected from Cu, Al, Cr, Pt, W, Nb, Ru, Ta, and Ti. At least one of them. These may be used individually by 1 type and may use 2 or more types together.

There is no restriction | limiting in particular as thickness of the said nonmagnetic layer, According to the objective, it can select suitably.
The formation of the nonmagnetic layer is not particularly limited and can be performed according to a known method. For example, it can be performed by electrodeposition (electrodeposition method) or the like.

In the magnetic recording medium of the present invention, a soft magnetic underlayer may be provided between the substrate and the porous layer.
There is no restriction | limiting in particular as a material of the said soft-magnetic underlayer, Although it can select suitably from well-known things, For example, what was mentioned above as a material of the said soft-magnetic layer is mentioned suitably. These materials may be used individually by 1 type, may use 2 or more types together, and may mutually be the same as the material of the said soft-magnetic layer, and may differ.

The soft magnetic underlayer preferably has an easy axis of magnetization in the in-plane direction of the substrate surface. In this case, a magnetic circuit in which the magnetic flux from the magnetic head used for magnetic recording is effectively closed can be formed, and the vertical component of the magnetic field of the magnetic head can be increased. The soft magnetic underlayer is also effective in single domain recording with a bit size (opening diameter of the nanohole) of 100 nm or less.
The formation of the soft magnetic underlayer is not particularly limited and can be performed according to a known method. For example, it can be performed by electrodeposition (electrodeposition method), electroless plating, or the like.

  There is no restriction | limiting in particular as said other layer, Although it can select suitably according to the objective, For example, an electrode layer, a protective layer, etc. are mentioned.

The electrode layer is a layer that functions as an electrode when the magnetic layer (the ferromagnetic layer and the soft magnetic layer) is formed by electrodeposition or the like, and is generally on the substrate and below the ferromagnetic layer. Provided. When the magnetic layer is formed by electrodeposition, the electrode layer may be used as an electrode, but the soft magnetic underlayer or the like may be used as an electrode.
There is no restriction | limiting in particular as a material of the said electrode layer, According to the objective, it can select suitably, For example, Cr, Co, Pt, Cu, Ir, Rh, these alloys, etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together. The electrode layer may further contain W, Nb, Ti, Ta, Si, O, etc. in addition to these materials.

There is no restriction | limiting in particular as thickness of the said electrode layer, According to the objective, it can select suitably. One electrode layer may be provided, or two or more electrode layers may be provided.
The formation of the electrode layer is not particularly limited and can be performed according to a known method. For example, the electrode layer can be formed by a sputtering method, a vapor deposition method, or the like.

The protective layer is a layer having a function of protecting the ferromagnetic layer, and is provided on the surface or above the ferromagnetic layer. The protective layer may be provided in only one layer, may be provided in two or more layers, may have a single layer structure, or may have a laminated structure.
There is no restriction | limiting in particular as a material of the said protective layer, According to the objective, it can select suitably, For example, DLC (diamond-like carbon) etc. are mentioned.

There is no restriction | limiting in particular as thickness of the said protective layer, According to the objective, it can select suitably.
The formation of the protective layer is not particularly limited and can be performed according to a known method according to the purpose. For example, the protective layer can be performed by a sputtering method, a plasma CVD method, a coating method, or the like.

The magnetic recording medium of the present invention can be used for various types of magnetic recording using a magnetic head, but can be suitably used for magnetic recording using a single pole head. It can be particularly suitably used for the recording method.
The magnetic recording medium of the present invention is capable of high-density recording and high-speed recording without increasing the write current of the magnetic head, has a large capacity, has excellent overwrite characteristics, uniform characteristics, and high quality. For this reason, the magnetic recording medium can be designed and used as various magnetic recording media. For example, the magnetic recording medium is designed for a hard disk device widely used as an external storage device of a computer, a consumer video recording device, or the like. It can be used, and can be particularly suitably designed and used for a magnetic disk such as a hard disk.

  The production of the magnetic recording medium of the present invention is not particularly limited and can be produced according to a known method, but can be suitably produced by the method for producing a magnetic recording medium of the present invention described below.

(Method of manufacturing magnetic recording medium)
The method for producing a magnetic recording medium according to the present invention is a method for producing the magnetic recording medium according to the present invention, and further includes at least a nanohole structure forming step (porous layer forming step) and a magnetic material filling step. Other processes such as a soft magnetic underlayer forming process, an electrode layer forming process, a nonmagnetic layer forming process, a protective layer forming process, and a polishing process, which are appropriately selected according to the above, are included.

The soft magnetic underlayer forming step is selected as necessary, and is a step of forming a soft magnetic underlayer on the substrate.
Examples of the substrate include those described above.
The soft magnetic underlayer can be formed according to a known method. For example, the soft magnetic underlayer may be formed by a vacuum film formation method such as a sputtering method (sputtering) or a vapor deposition method, or an electrodeposition (electrodeposition method). Alternatively, it may be formed by electroless plating.
In the soft magnetic underlayer forming step, the soft magnetic underlayer having a desired thickness is formed on the substrate.

The electrode layer forming step is a step of forming an electrode layer between the nanohole structure and the soft magnetic underlayer.
The electrode layer can be formed according to a known method, but can be suitably performed by, for example, a sputtering method (sputtering) or a vapor deposition method. There is no restriction | limiting in particular as formation conditions of this electrode layer, According to the objective, it can select suitably.
The electrode layer formed in the electrode layer forming step is used as an electrode when forming at least one of a soft magnetic layer, a nonmagnetic layer, and a ferromagnetic layer by electrodeposition.

The nanohole structure forming step (porous layer forming step) includes a nanohole structure (on the soft magnetic underlayer when the soft magnetic underlayer is formed by the soft magnetic underlayer forming step) ( After forming a metal layer made of a metal material for forming a porous layer), a groove portion and a land portion are formed in the metal layer, and anodization is performed, so that nanoholes are formed in a direction substantially perpendicular to the substrate surface. This is a step of forming a nanohole structure (porous layer) by forming a plurality of column pairs.
As said metal material, what was mentioned above is mentioned, For example, an alumina (aluminum oxide), aluminum, etc. are mentioned suitably. Among these, aluminum is particularly preferable.

  The metal layer can be formed according to a known method, but can be suitably performed by, for example, a sputtering method (sputtering) or a vapor deposition method. There is no restriction | limiting in particular as formation conditions of this metal layer, According to the objective, it can select suitably. In the case of the sputtering method, sputtering can be performed using a target formed of the metal material. The target used in this case preferably has a high purity, and when the metal material is aluminum, the target is preferably 99.990% or more.

  The formation of the land portion and the groove portion is not particularly limited and can be performed according to a known method, but is preferably performed by forming a concave line on the metal substrate. In this case, the concave line (recessed part) formed on the metal base corresponds to the groove part, and the convex line on the metal base (the convex part formed on the portion excluding the concave line) It corresponds to the land portion. And the said nanohole row | line | column pair can be efficiently formed only on the said concave line (groove part).

  The width of the groove portion and the land portion is not particularly limited and can be appropriately selected according to the purpose. The width of the land portion (Y in FIG. 8A) is the width of the groove portion (FIG. 8A). It is preferably larger than X) and less than 2 times, more preferably 1.8 times or less. When the widths of the groove part and the land part satisfy the numerical range, the distance between one nanohole array and the nanohole array pair adjacent to the one nanohole array pair is a pair in the one nanohole array pair. Thus, the distance (interval) between the two nanohole arrays becomes wider, and the nanohole pairs can be separated from each other. In this case, when the nanohole structure is applied to a magnetic disk, cross-write and cross-read between the nanohole pairs can be reduced. Further, a different function can be imparted to each nanohole array in the array pattern. For example, for each nanohole array, a DNA chip in which different DNA is arranged in the nanohole in the nanohole array, It can be used for a protein detection apparatus provided with an antibody or the like.

Further, the width of the groove portion may be changed (wide or narrow) at regular intervals (constant period) in the length direction. In this case, as shown in FIGS. 7A and 7B, the nanoholes are easily formed in a portion where the width of the groove portion is wide, so that the arrangement state of the nanoholes in the nanohole array pair can be changed.
For example, as shown in FIG. 7A, when the width of the groove portion is formed in a wave shape widened at regular intervals (constant period) in the length direction, two nanoholes are formed in the wide portion of the groove portion. Therefore, the nanohole array pair in which the nanoholes are arranged in a square lattice shape can be formed. Furthermore, for example, as shown in FIG. 7B, when the width of the wavy groove portion is formed by shifting the width of the groove portion by half a period, the nanoholes are formed in the wide portion of the groove portion, At this time, since the arrangement interval of the nanoholes is shifted by a half cycle for each nanohole row, the nanohole row pair in which the nanoholes are arranged in a triangular lattice shape can be formed. In addition, since the nanohole is formed more stably in the triangular lattice arrangement than in the square lattice arrangement, the triangular lattice arrangement can be formed when the square lattice arrangement is disturbed. It is preferable to form the groove portion.

  The method for forming the concave line is not particularly limited and may be appropriately selected depending on the intended purpose. For example, (1) convex lines (nanoholes) in which convex lines and spaces are arranged at regular intervals When the structure is applied to a magnetic disk or the like, a mold having a concentric or spiral convex line) as a surface shape (a disk-shaped mold when the nanohole structure is applied to a magnetic disk or the like) is used. A method of imprint transfer onto the surface of the metal layer (for example, alumina, aluminum, etc.) to form a concave line in which concave lines and spaces are arranged at regular intervals, and (2) a resin layer on the metal layer And a method of forming a concave line on the surface of the metal layer by patterning and etching the layer after forming a photoresist layer, and (3) before Directly on the metal layer, a method of forming a groove (concave lines), and the like.

  At this time, by changing the width of the convex line in the mold, the width of the concave line pattern formed in the photoresist layer, etc. at regular intervals (constant period) in the length direction, the nanohole array The arrangement state of the nanoholes in the pair can be changed, and can be aligned with higher density. In this case, it is preferable to apply the nanohole structure to a magnetic recording medium in that the jitter is reduced and high-density recording is possible.

  There is no restriction | limiting in particular as said mold, Although it can select suitably according to the objective, From a viewpoint of continuous use durability, a silicon carbide substrate etc. are mentioned, Moreover, it is used for the shaping | molding of an optical disk, etc. Ni stamper etc. are also mentioned. The mold can be used multiple times. There is no restriction | limiting in particular as the method of the said imprint transfer, According to the objective, it can select suitably from well-known methods. The resist material for the photoresist layer includes not only a photoresist material but also an electron beam resist material. There is no restriction | limiting in particular as said photoresist material, It can select suitably from well-known materials in the semiconductor field | area etc., For example, the material etc. which can utilize near ultraviolet light, near-field light, etc. are mentioned.

  The anodic oxidation treatment can be performed by electrolytic etching in an aqueous solution of sulfuric acid, phosphoric acid or oxalic acid using the electrode in contact with the metal layer as an anode. Examples of the electrode include the soft magnetic underlayer and the electrode layer formed prior to forming the metal layer.

Moreover, as the voltage in the anodizing treatment, it is necessary to select a voltage having a value given by either of the following formula (1) and the following formula (2).
Groove width (nm) / A (nm / V) (1)
Groove width (nm) / (√3 / 2) / A (nm / V) (2)
However, in said Formula (1) and said Formula (2), A is 2.0-3.0, 2.5 +/- 0.2 is preferable and 2.5 is especially preferable. When the A is in the range of 2.0 to 3.0, the nanohole array pair can be formed in the groove portion.

  When the voltage is a value selected from the range given by either the formula (1) or the formula (2), it is advantageous in that the nanohole array pair can be formed in the groove portion. . Further, when the anodization treatment is performed at a voltage selected from the range given by the formula (1), as shown in FIG. 8A, nanohole array pairs in which the nanoholes are arranged in a triangular lattice can be formed. When the anodizing treatment is performed at a voltage selected from the range given by Equation (2), a nanohole array pair in which the nanoholes are arranged in a square lattice can be formed as shown in FIG. 8B.

  In addition, there is no restriction | limiting in particular as a kind, density | concentration, temperature, time, etc. of the electrolyte solution in the said anodizing process, According to the number of nanoholes to form, a magnitude | size, an aspect-ratio, etc., it can select suitably. For example, as the type of the electrolytic solution, when the interval (pitch) between adjacent nanohole rows is 150 nm to 500 nm, a diluted phosphoric acid solution is preferably used, and when it is 80 nm to 200 nm, diluted oxalic acid is used. A solution is mentioned suitably, and when it is 10 nm-150 nm, a dilute sulfuric acid solution is mentioned suitably. In any case, the adjustment of the aspect ratio of the nanohole can be performed by increasing the diameter of the nanohole (alumina pore) by immersing in a phosphoric acid solution after the anodizing treatment.

When the nanohole structure forming step (porous layer forming step) is performed by the anodizing treatment, many nanoholes can be formed in the metal layer, but a barrier layer may be formed below the nanoholes. However, the barrier layer can be easily removed by performing a known etching process using a known etching solution such as phosphoric acid. As described above, a large number of nanohole array pairs exposing the soft magnetic underlayer or the substrate can be formed in the metal layer in a direction substantially perpendicular to the substrate surface.
By the nanohole structure forming step (porous layer forming step), the nanohole structure (porous layer) is formed on the substrate or the soft magnetic underlayer.

  The magnetic material filling step is a step of filling the nanohole formed in the nanohole structure (porous layer) with a magnetic material, and a ferromagnetic layer forming step of filling the nanohole with the ferromagnetic material, Including a soft magnetic layer forming step of filling the nanohole with the soft magnetic material.

The soft magnetic layer forming step is a step of forming a soft magnetic layer inside the nanohole.
The soft magnetic layer can be formed by depositing or filling the above-described soft magnetic layer material into the nanoholes by electrodeposition or the like.
The electrodeposition method, conditions, etc. are not particularly limited and may be appropriately selected according to the purpose. For example, the electrodeposition material includes the soft magnetic underlayer or the electrode layer as an electrode. Preferred examples include a method of depositing or depositing on the electrode by applying one or more kinds of solutions and applying a voltage.
By the soft magnetic layer forming step, the soft magnetic layer is formed inside the nanohole in the porous layer, on the substrate, on the soft magnetic underlayer, or on the electrode layer.

The ferromagnetic layer forming step is a step of forming a ferromagnetic layer on the soft magnetic layer (or on the nonmagnetic layer when the nonmagnetic layer is formed on the soft magnetic layer).
The ferromagnetic layer can be formed by depositing or filling the above-described ferromagnetic layer material on the soft magnetic layer formed inside the nanohole by electrodeposition or the like.
The electrodeposition method, conditions, and the like are not particularly limited and can be appropriately selected depending on the purpose. For example, the material includes the ferromagnetic layer using the soft magnetic underlayer or the electrode layer as an electrode. Preferred examples include a method of depositing or depositing in the nanohole by applying one or more kinds of solutions and applying a voltage.
By the ferromagnetic layer forming step, the ferromagnetic layer is formed inside the nanohole in the porous layer and on the soft magnetic layer or the nonmagnetic layer.

The nonmagnetic layer forming step is a step of forming a nonmagnetic layer on the soft magnetic layer.
The nonmagnetic layer can be formed by depositing or filling the above-described nonmagnetic layer material on the soft magnetic layer formed inside the nanohole by electrodeposition or the like.
The electrodeposition method, conditions, and the like are not particularly limited and can be appropriately selected depending on the purpose. For example, the electrodeposition layer includes the soft magnetic underlayer or the electrode layer as an electrode, and includes the material of the nonmagnetic layer. A method of depositing or depositing in a nanohole by applying one or more kinds of solutions and applying a voltage is preferable.
By the nonmagnetic layer forming step, the nonmagnetic layer is formed inside the nanohole in the porous layer and on the soft magnetic layer or the like.

The polishing step is a step of polishing and planarizing the surface of the nanohole structure (porous layer) after the magnetic layer forming step (including the ferromagnetic layer forming step and the soft magnetic layer forming step). is there.
There is no restriction | limiting in particular as the method of grinding | polishing in the said grinding | polishing process, It can carry out according to a well-known method. When the surface of the magnetic recording medium is smoothed by the polishing step, a magnetic head such as a perpendicular magnetic recording head can be stably levitated, and both high density recording and low reliability can be achieved by low levitating. This is advantageous in that

  According to the method for manufacturing a magnetic recording medium of the present invention, the magnetic recording medium of the present invention can be manufactured efficiently and at low cost.

(Magnetic recording apparatus and magnetic recording method)
The magnetic recording apparatus of the present invention comprises the magnetic recording medium of the present invention and a perpendicular magnetic recording head, and further comprises other means or members appropriately selected as necessary.
The magnetic recording method of the present invention includes recording on the magnetic recording medium of the present invention using a perpendicular magnetic recording head, and further includes other processes or steps appropriately selected as necessary. The magnetic recording method of the present invention can be preferably carried out using the magnetic recording apparatus of the present invention. The other processes or steps can be performed by the other means or members. Hereinafter, the magnetic recording method of the present invention will be described together with the description of the magnetic recording apparatus of the present invention.

  The perpendicular magnetic recording head is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a single magnetic pole head or the like is preferable. The perpendicular magnetic recording head may be dedicated for writing, or may be for writing and reading integrated with a reading head such as a GMR head.

In the magnetic recording by the magnetic recording apparatus of the present invention or the magnetic recording by the magnetic recording method of the present invention, since the magnetic recording medium of the present invention is used, the perpendicular magnetic recording head and the soft magnetic layer in the magnetic recording medium are used. Is shorter than the thickness of the porous layer and is substantially equal to the thickness of the ferromagnetic layer, so that the perpendicular magnetic field can be obtained only by the thickness of the ferromagnetic layer regardless of the thickness of the porous layer. It is possible to control the concentration of magnetic flux from the recording head, the optimum magnetic recording / reproducing characteristics at the used recording density, and the like. Therefore, as shown in FIG. 5, the magnetic flux from the main magnetic pole 100 of the perpendicular magnetic recording head (write / read head) is concentrated on the ferromagnetic layer (perpendicular magnetization film) 30, resulting in the conventional magnetic field. Compared with the recording apparatus, the writing efficiency is greatly improved, the writing current is small, and the overwrite characteristic is remarkably improved.
It is preferable that the soft magnetic underlayer is formed on the magnetic recording medium because a magnetic circuit is formed between the perpendicular magnetic recording head and the soft magnetic underlayer. This is advantageous in that high density recording is possible.

In the magnetic recording by the magnetic recording apparatus of the present invention or the magnetic recording by the magnetic recording method of the present invention, the magnetic flux from the perpendicular magnetic recording head is applied to the ferromagnetic layer of the magnetic recording medium by the lower surface of the ferromagnetic layer. That is, even in the vicinity of the interface with the soft magnetic layer or the non-magnetic layer, it does not diffuse while being concentrated, so that a small bit can be written.
The degree of convergence (degree of diffusion) of the magnetic flux in the ferromagnetic layer is not particularly limited as long as the effect of the present invention is not impaired, and can be appropriately selected according to the purpose.

  Hereinafter, although the Example of this invention is described, this invention is not limited to this Example at all. In the following examples, the magnetic recording medium of the present invention having the nanohole structure of the present invention is manufactured by the method of manufacturing the magnetic recording medium of the present invention, and magnetic recording is performed by the magnetic recording apparatus of the present invention. The magnetic recording method is performed.

Example 1
-Fabrication of nanohole structures-
Using an EB exposure apparatus, a concavo-convex pattern was formed by drawing lines on a 40 nm thick resist layer spin-coated on a glass substrate. In the concave / convex pattern, the interval (pitch) between the convex lines is 100 nm, the widths of the convex lines and the concave lines are both 50 nm, and the height of the convex lines is 40 nm. Next, a Ni layer is formed on the surface of the concavo-convex pattern by sputtering, and using this as an electrode, electroforming is performed using a nickel sulfamate bath until the thickness of the nickel layer becomes 0.3 mm, and the back surface is polished. As a result, a Ni stamper mold 54 was obtained as shown in FIG. 9A.
Next, as shown in FIG. 9A, the obtained Ni stamper mold 54 was placed on the aluminum substrate 52 as the metal base material. Then, as shown in FIG. 9B, the Ni stamper mold 54 was pressed against the aluminum substrate 52 to imprint and transfer the uneven pattern formed on the surface of the Ni stamper mold 54 onto the surface of the aluminum substrate 52. The aluminum substrate 52 is of 5N purity, the surface is smoothed by electrolytic polishing in advance, and the pressing pressure during imprint transfer was 2,400 kg / cm ² . As a result, as shown in FIG. 9C, a concavo-convex pattern 56 in which a plurality of groove portions (concave lines) G and land portions (convex lines) L were alternately arranged was formed on the surface of the aluminum substrate 52. The interval (pitch) between the groove portions (concave lines) G is 100 nm, the width of the land portions (convex lines) L and the width of the groove portions (concave lines) G are both 50 nm, and the groove portions ( The depth of the concave line G is 40 nm.
Next, as shown in FIG. 9D, the aluminum substrate 52 after imprint transfer was placed in a 0.3 M sulfuric acid aqueous solution at 30 ° C. using 23 V (the above equation (2), groove width = 50 nm, A = Anodization was performed for 2 minutes at a constant voltage of 2.5). When the obtained pore arrangement (nanohole structure) was observed using a scanning electron microscope (SEM), a structure as shown in FIG. 10 was obtained.
As shown in FIG. 10, nanohole rows in which pores (nanoholes) are arranged along edges at both ends of the bottom of the groove part (concave line), and nanoholes are regularly arranged only in each groove. Are arranged at regular intervals. In addition, it was confirmed that the nanoholes were regularly arranged in a one-dimensional manner with a period of 50 nm in the vertical direction of the concavo-convex line, and it was found that the interval between the nanohole rows in the nanohole row pair was 50 nm. Moreover, the space | interval of adjacent nanoholes was 55-60 nm, and the opening diameter of the nanohole was 20 nm.
Furthermore, when the obtained structure (nanohole structure) was fractured and the fractured surface was observed by SEM, the pores (nanoholes) were perpendicular to the surface of the structure as shown in FIG. It was confirmed.
In addition, by performing ion milling under conditions of 6 kV, 30 mA, and 10 °, the surface of the structure is etched while the surface of the structure is etched in the order of blank (initial), 15 minutes, 30 minutes, and 60 minutes. Observations were made. In FIG. 12, the SEM photograph after each time passage is shown. An SEM photograph of the fracture surface of the structure is also shown in FIG. From FIG. 12, it was found that pores (nanoholes) were arranged in a triangular lattice array up to the bottom of the structure.

The formation mechanism of the nanohole array pair considered from the above results is shown in FIGS. 13A and 13B. That is, in the nanohole structure shown in FIG. 10, as schematically shown in FIG. 13A, nanohole rows are arranged along the edge of the groove portion G, and in the groove portion G, the nanohole rows are arranged in two rows at regular intervals. Nanohole array pairs formed at regular intervals. In addition, nanoholes in two nanohole rows (two left and right nanohole rows arranged along the edge of the groove portion G) in the nanohole row pair are arranged in a triangular lattice pattern. Then, as shown in FIG. 13B, when alumina pores (nanoholes) are grown, the dot interval (pitch interval of alumina pores) P _dot = 23 V (anodization voltage) × 2.5 under the anodizing conditions of Example 1. = 57.5 nm. Since the dot interval P _dot is exactly 2 / √3 times the groove width W _groove (50 nm), the condition that the cells of alumina pores that grow isotropically circularly are arranged in a triangular lattice shape is satisfied, As a result, as shown in FIG. 10 and FIG. 13A, it is realized that nanohole array pairs composed of two nanohole arrays are arranged at regular intervals in the groove portion G based on the triangular lattice arrangement of nanoholes. It is thought that.

(Example 2)
In Example 1, except that the voltage in the anodic oxidation treatment was changed to a constant voltage of 20 V (a voltage given on the condition that the groove width = 50 nm and A = 2.5 using the formula (1)). In the same manner as in Example 1, a nanohole structure was produced. In the obtained nanohole structure, it was confirmed that the nanoholes were regularly arranged in a one-dimensional manner with a period of 50 nm in the vertical direction of the concavo-convex line, and the interval between the nanohole rows in the nanohole row pair was 50 nm. I found out. The opening diameter of the nanohole was 18 nm.

Based on the results and discussion of Example 1, the formation mechanism of nanohole array pairs is shown in FIGS. 14A and 14B in the same manner as in Example 1. FIG. That is, in the nanohole structure obtained in Example 2, as schematically shown in FIG. 14A, nanohole rows are arranged along the edge of the groove portion G, and in the groove portion G, the nanohole rows are arranged at regular intervals. Two rows of nanohole row pairs are formed at regular intervals. In addition, nanoholes in two nanohole rows (two left and right nanohole rows arranged along the edge of the groove portion G) in the nanohole row pair are arranged in a square lattice pattern. Then, as shown in FIG. 14B, when alumina pores (nanoholes) grow, the dot interval (alumina pore pitch interval) P _dot = 20 V (anodization voltage) × 2.5 under the anodizing conditions of Example 2. = 50 nm. Since the dot interval P _dot is equal to the _groove width W _groove (50 nm), the condition that the cells of the alumina pores that are isotropically circularly grow are arranged in a square lattice shape is satisfied. As shown in FIG. 14A, it is considered that the arrangement of nanohole array pairs consisting of two nanohole arrays in the groove portion G based on the square lattice array of nanoholes at regular intervals was realized. In addition, the nanohole structure in which nanoholes are arranged in a square lattice in Example 2 is inferior to the stability of the arrangement of nanoholes in comparison with the nanohole structure in which nanoholes are arranged in a triangular lattice in Example 1, Some disorder of the arrangement was observed.

(Example 3)
In Example 1, a nanohole structure was manufactured in the same manner as in Example 1 except that the uneven pattern was formed so that the width of the land portion L and the width of the groove portion G were different.
That is, in Example 3, a Ni stamper mold was prepared by changing the width of the convex line to 50 nm and the width of the concave line to 100 nm in the Ni stamper mold in Example 1, and using the Ni stamper mold. An uneven pattern in which a plurality of groove portions (concave line: width 50 nm) G and land portions (convex line: width 100 nm) L are alternately formed is formed on the surface of the aluminum substrate, and then anodization is performed. It was. The arrangement | sequence aspect of a nanohole row | line | column pair in the obtained nanohole structure is shown to FIG. 15A and FIG. 15B.

  As schematically shown in FIG. 15A, nanohole rows are arranged along the edge of the groove portion G, and in the groove portion G, nanohole row pairs in which two nanohole rows are arranged at regular intervals are formed. An alumina pore (nanohole) is also formed at the center of the portion L, and a nanohole array is arranged. Then, as shown in FIG. 15B, when alumina pores (nanoholes) are grown, nanohole array pairs consisting of two nanohole arrays can be arranged in the groove G based on the triangular lattice arrangement of nanoholes. In the land portion L, nanohole rows based on a triangular lattice arrangement are formed in the same manner as the nanoholes in the groove portion G. As a result, the nanohole row pairs are spaced apart from each other at regular intervals via the land portion L. Could not be formed.

Example 4
In Example 3, an uneven pattern in which a plurality of groove portions (concave lines) G and land portions (convex lines) L are alternately arranged on the surface of an aluminum substrate is used, and the width W _{land of the land} portions L is the groove portion G. After being formed so as to be 1.6 times the width W _groove of the anodic layer, anodizing treatment was performed at a voltage given by the above formula (1). The arrangement | sequence aspect of a nanohole row | line | column pair in the obtained nanohole structure is shown to FIG. 16A and FIG. 16B.

  As schematically shown in FIG. 16A, nanohole rows are arranged along the edge of the groove portion G, and only in the groove portion G, nanohole row pairs in which two nanohole rows are arranged at regular intervals are formed. In the part L, alumina pores (nanoholes) were not formed. Then, as shown in FIG. 16B, when alumina pores (nanoholes) are grown, a nanohole array pair consisting of two nanohole arrays can be arranged in the groove part G, based on a nanohole square lattice array, The nanohole array pairs were separated by land portions L at regular intervals.

From the results of Example 3 and Example 4, it is preferable that the width W _land of the _land portion L is less than twice the width W _groove of the groove portion G in order not to form the nanohole array in the land portion L. I found out.

(Example 5)
In the same manner as in Example 1 and Example 2, pairs of nanoholes formed by arranging two nanoholes at intervals of 50 nm were formed at regular intervals. Subsequently, electrolytic deposition was performed for 10 minutes in an electrolytic solution of cobalt sulfate heptahydrate 50 g / l and boric acid 20 g / l under conditions of 50 Hz and 10 V. As shown in FIG. Cobalt (Co) 59 was filled in the nanoholes. After removing cobalt (Co) deposited on the surface of the nanoholes by polishing, the surface was observed with a scanning electron microscope (SEM). As a result, cobalt (Co) regularly arranged in a one-dimensional manner with a width of 50 nm was confirmed. It was.

(Example 6)
The nanohole structure of the present invention was applied to a magnetic recording medium (magnetic disk), a magnetic recording medium (magnetic disk) was produced as follows, and the characteristics were evaluated as follows.

-Soft magnetic underlayer formation process-
The soft magnetic underlayer forming step was performed by forming (stacking) FeCoNiB as a soft magnetic underlayer on a glass substrate to a thickness of 500 nm by an electroless plating method.

-Nanohole structure formation process (porous layer formation process)-
The nanohole structure forming step was performed as follows. That is, Nb was laminated to a thickness of 5 nm and Al was laminated to a thickness of 150 nm on the soft magnetic underlayer by sputtering. By a method similar to that of Example 1, a Ni stamper mold having an outer size of 1 inch having a concentric line / space (uneven line pitch: 100 nm, land width and groove width, both 50 nm) pattern as a surface shape was produced. Using the Ni stamper mold, a concave line was imprinted onto an aluminum (Al) layer located on the surface of the substrate.
Next, the sample after imprint transfer is given in a 0.3 M sulfuric acid aqueous solution (bath temperature 30 ° C.), 23 V (using the above equation (2), groove width = 50 nm, A = 2.5). Anodization was performed at a constant voltage of 2 minutes for 2 minutes to form nanoholes (alumina pores). The opening diameter of the nanohole was 20 nm. Thus, the nanohole structure forming step was performed.

-Magnetic material filling process-
Next, electrolytic deposition was performed for 10 minutes in an electrolytic solution of cobalt sulfate heptahydrate 50 g / l and boric acid 20 g / l under conditions of 50 Hz and 10 V, and in the nanoholes as the ferromagnetic material. The magnetic material filling step was performed by filling cobalt (Co) in this manner and forming a ferromagnetic layer in the nanohole. Thus, a magnetic disk was manufactured.

-Polishing process-
The polishing step was performed as follows. That is, for the purpose of floating the magnetic head, surface polishing was performed using a wrapping tape. As the wrapping tape, a tape having a particle size of 3 μm alumina was used to rough-polish the convex alumina present on the surface where the nanoholes were opened, and then a final polishing was performed using a tape having a particle size of 0.3 μm alumina. . The thickness of the porous layer (alumina layer) after this polishing step was about 100 nm, and the aspect ratio of the nanohole (alumina pore) filled with cobalt (Co) was about 5.

  Thereafter, a carbon protective film was formed on the surface of the polished magnetic disk, and perfluoropolyether (manufactured by Solvay Solexis, AM3001) as a lubricant was applied by a dip method to obtain a magnetic disk sample for characteristic evaluation.

Using the magnetic recording device provided with the single magnetic pole head as the magnetic head for writing and the GMR head as the magnetic head for reading, the obtained magnetic disk sample for characteristic evaluation was written using the single magnetic pole head, and Magnetic recording was performed by reading the GMR head, and the recording / reproducing characteristics were evaluated.
First, the magnetic disk sample for characteristic evaluation is magnetized in one direction perpendicular to the substrate surface by a permanent magnet, and then the magnetic disk sample for characteristic evaluation is rotated to float the magnetic head to record and reproduce the magnetic signal. went. As a result, regular signals corresponding to nanohole array pairs arranged circumferentially were observed.

In the magnetic disk sample for characteristic evaluation of the present invention, a nanohole array pair in which two nanohole arrays are arranged at an interval (pitch) of 50 nm is formed even if a conventional line / space pattern with an uneven line pitch of 100 nm is used. Therefore, the row density of the nanohole row is doubled, and the recording density of the magnetic disk can be doubled. If the uneven line pitch is 50 nm, the width of the groove G becomes 25 nm, and a nanohole array pair in which two nanohole arrays are arranged at intervals (pitch) of 25 nm can be formed in the groove portion G. 1Tbit A recording density of / in ² can also be realized.

The preferred embodiments of the present invention are as follows.
(Supplementary note 1) A nanohole structure characterized in that a nanohole array in which nanoholes are arranged one-dimensionally on a metal substrate is paired at a predetermined interval to form a nanohole array pair.
(Supplementary note 2) The nanohole structure according to supplementary note 1, wherein the nanohole structure has a concavo-convex line in which groove portions and land portions are alternately arranged, and a nanohole array pair is formed only in the groove portion.
(Supplementary note 3) Any one of Supplementary notes 1 to 2, wherein an interval between nanohole rows in one nanohole row pair is substantially the same as a gap between the one nanohole row pair and the adjacent nanohole row pair. The nanohole structure according to crab.
(Additional remark 4) The space | interval of one nanohole row | line | column pair and the nanohole row | line | column pair adjacent to this one nanohole row | line | column pair is larger than the space | interval between nanohole row | line | columns in the said one nanohole row | line | column pair, and less than 2 times. The nanohole structure according to any one of 1 to 2.
(Additional remark 5) The space | interval of one nanohole row | line | column pair and this nanohole row | line | column pair and an adjacent nanohole row | line | column pair is larger than the space | interval between nanohole row | line | columns in a nanohole row pair, and is 1.8 times or less. The nanohole structure according to 1.
(Appendix 6) The nanohole structure according to any one of appendices 1 to 5, wherein the metal substrate is an aluminum substrate.
(Supplementary note 7) The nanohole structure according to any one of supplementary notes 1 to 6, wherein the metal substrate is in a disk shape, and the nanohole array pair is positioned in at least one of a concentric circle shape and a spiral shape.
(Supplementary note 8) The nanohole structure according to supplementary note 7, wherein nanoholes in adjacent nanohole array pairs are arranged in a radial direction.
(Supplementary note 9) The nanohole structure according to any one of supplementary notes 1 to 6, wherein an opening diameter of the nanohole is 100 nm or less.
(Appendix 10) A method for producing the nanohole structure according to any one of appendices 1 to 9,
A nanohole formation processing step of forming a nanohole array pair by forming a groove portion and a land portion on a metal substrate and then anodizing with a voltage given by either of the following formula (1) and the following formula (2) A method for producing a nanohole structure, comprising:
Groove width (nm) / A (nm / V) (1)
Groove width (nm) / (√3 / 2) / A (nm / V) (2)
However, in said Formula (1) and said Formula (2), A is 2.0-3.0.
(Additional remark 11) The manufacturing method of the nanohole structure of Additional remark 10 whose A in Formula (1) and Formula (2) is 2.5 +/- 0.2.
(Supplementary note 12) The method for producing a nanohole structure according to any one of supplementary notes 10 to 11, wherein the groove part and the land part are formed by forming a concave line on the metal substrate.
(Additional remark 13) The manufacturing method of the nanohole structure in any one of Additional remark 10 to 12 whose width | variety of a land part is substantially the same as the width | variety of a groove part.
(Additional remark 14) The manufacturing method of the nanohole structure in any one of Additional remark 10 to 12 whose width of a land part is larger than the width of a groove part, and is less than 2 times.
(Additional remark 15) The manufacturing method of the nanohole structure of Additional remark 14 whose width of a land part is larger than the width of a groove part, and is 1.8 times or less.
(Supplementary note 16) The method for producing a nanohole structure according to any one of supplementary notes 10 to 15, wherein the width of the concave line is changed at regular intervals in the length direction thereof.
(Supplementary Note 17) Any one of Supplementary Notes 10 to 16, wherein the concave line is formed by imprinting a disk-shaped mold having a concave-convex line formed in the circumferential direction on a metal substrate. The manufacturing method of the nanohole structure as described in 1 ..
(Supplementary Note 18) A porous layer in which a plurality of nanoholes are formed in a direction substantially orthogonal to the substrate surface on a substrate, and a magnetic material is included inside the nanoholes.
A magnetic recording body, wherein the porous layer is a nanohole structure according to any one of appendices 1 to 9.
(Supplementary note 19) The magnetic recording according to supplementary note 18, wherein the nanohole includes a soft magnetic layer and a ferromagnetic layer in this order from the substrate side, and the thickness of the ferromagnetic layer is equal to or less than the thickness of the soft magnetic layer. Medium.
(Supplementary note 20) The magnetic recording medium according to any one of supplementary notes 18 to 19, wherein a soft magnetic underlayer is provided between the substrate and the porous layer.
(Supplementary note 21) The magnetic layer according to any one of supplementary notes 19 to 20, wherein the ferromagnetic layer is formed of at least one selected from Fe, Co, Ni, FeCo, FeNi, CoNi, CoNiP, FePt, CoPt, and NiPt. recoding media.
(Supplementary note 22) The magnetic recording medium according to any one of supplementary notes 19 to 21, wherein the soft magnetic layer is formed of at least one selected from NiFe, FeSiAl, FeC, FeCoB, FeCoNiB, and CoZrNb.
(Supplementary note 23) A method of manufacturing the magnetic recording medium according to any one of supplementary notes 18 to 22,
After forming a metal layer on the substrate, a groove portion and a land portion are formed in the metal layer, and anodized with a voltage given by either of the following formula (1) and the following formula (2), A nanohole structure forming step of forming a nanohole structure by forming a plurality of nanohole array pairs in a direction substantially orthogonal to the substrate surface; and a magnetic material filling step of filling a magnetic material inside the nanoholes in the nanohole array pair; A method for manufacturing a magnetic recording medium, comprising:
Groove width (nm) / A (nm / V) (1)
Groove width (nm) / (√3 / 2) / A (nm / V) (2)
However, in said Formula (1) and said Formula (2), A is 2.0-3.0.
(Additional remark 24) The manufacturing method of the magnetic recording medium of Additional remark 23 whose width of a land part is larger than the width of a groove part, and is less than 2 times.
(Additional remark 25) The manufacturing method of the magnetic recording medium in any one of Additional remark 23 to 24 whose width of a land part is larger than the width of a groove part, and is 1.8 times or less.
(Supplementary note 26) From supplementary note 23, the magnetic material filling step includes a soft magnetic layer forming step of forming a soft magnetic layer inside the nanohole, and a ferromagnetic layer forming step of forming a ferromagnetic layer on the soft magnetic layer. 26. A method for producing a magnetic recording medium according to any one of 25.
(Additional remark 27) The manufacturing method of the magnetic recording medium in any one of additional marks 23 to 26 including the grinding | polishing process of grind | polishing the surface of a nanohole structure after a magnetic material filling process.

The nanohole structure of the present invention can be suitably used in various fields such as a magnetic recording medium, a DNA chip, a diagnostic device, a detection sensor, a catalyst substrate, a field emission display, and in particular, an external storage device of a computer, It can be suitably used for a hard disk device or the like widely used as a consumer video recording device or the like.
The magnetic recording medium of the present invention can be suitably used for hard disk drives and the like that are widely used as external storage devices for computers, consumer video recording devices, and the like.
The method for producing a magnetic recording medium of the present invention can be suitably used for producing the magnetic recording medium of the present invention.
The magnetic recording device of the present invention can be suitably used as a hard disk device or the like widely used as an external storage device of a computer, a consumer video recording device or the like.
The magnetic recording method of the present invention is capable of high-density recording and high-speed recording without increasing the write current of the magnetic head, has a large capacity, has excellent overwrite characteristics, and has uniform characteristics. Therefore, it can be suitably used for extremely high quality recording.

FIG. 1 is a conceptual diagram showing an example of performing magnetic recording by the perpendicular recording method. FIG. 2A is a conceptual diagram for explaining an example of a state in which magnetic flux is diffused during magnetic recording by the perpendicular recording method. FIG. 2B is a conceptual diagram for explaining an example of a state in which magnetic flux is concentrated without being diffused during magnetic recording by the perpendicular recording method. FIG. 3 is a schematic explanatory view showing an example of a magnetic recording medium obtained by filling a pore of an anodized alumina pore with a magnetic metal and combining a patterned medium and a perpendicular recording method. FIG. 4A is a schematic explanatory diagram showing an example of a magnetic recording medium in which magnetic metals are filled in two-dimensionally arranged anodized alumina pores. 4B is a cross-sectional view taken along line B-B ′ of FIG. 4A. FIG. 5 is a partial cross-sectional schematic explanatory view showing an example of a state in which magnetic recording is performed on a magnetic recording medium by a perpendicular magnetic recording method using a single magnetic pole head. FIG. 6A is a photograph for explaining an example of the surface state of the aluminum layer after imprint transfer of the mold. FIG. 6B is a photograph showing an example of a state in which nanohole arrays are formed by anodizing the aluminum layer shown in FIG. 6A. FIG. 7A is a schematic explanatory diagram illustrating an example of groove portions (embodiments partitioned at regular intervals) formed in the method for manufacturing a nanohole structure according to the present invention. FIG. 7B is a schematic explanatory diagram illustrating an example of groove portions (embodiments partitioned at regular intervals) formed in the method for manufacturing a nanohole structure according to the present invention. FIG. 8A is a schematic explanatory view showing an example (triangular lattice arrangement) of nanohole arrangement modes in a pair of nanoholes formed in the groove portion by the method for producing a nanohole structure of the present invention. FIG. 8B is a schematic explanatory view showing an example (square lattice arrangement) of nanohole arrangements in a pair of nanoholes formed in the groove portion by the method for producing a nanohole structure of the present invention. FIG. 9A is a process diagram (part 1) for explaining an example of the method for producing a nanohole structure according to the present invention. FIG. 9B is a process diagram (part 2) for explaining an example of the method for producing a nanohole structure according to the present invention. FIG. 9C is a process diagram (part 3) for explaining an example of the method for producing a nanohole structure according to the present invention. FIG. 9D is a process diagram (part 4) for explaining an example of the method for producing a nanohole structure according to the present invention. FIG. 10 is a photograph showing an example of the surface of a nanohole structure in which nanohole array pairs are formed. FIG. 11 is a photograph showing an example of a fracture surface of a nanohole structure in which nanohole array pairs are formed. FIG. 12 is a photograph showing the result of observing the arrangement of nanohole array pairs while etching the surface of the nanohole structure. FIG. 13A is a schematic explanatory diagram illustrating an example of a formation mechanism of a nanohole array pair. FIG. 13B is a schematic explanatory diagram illustrating an example of a formation mechanism of the nanohole array pair and illustrating a state after the growth of the nanohole in FIG. 13A. FIG. 14A is a schematic explanatory diagram illustrating another example of a mechanism for forming nanohole array pairs. FIG. 14B is a schematic explanatory diagram showing another example of the formation mechanism of the nanohole array pair and showing the state after the nanohole growth in FIG. 14A. FIG. 15A is a schematic explanatory diagram showing an example of a nanohole array pair formation mechanism when anodizing is performed with the width of the land portion being twice that of the groove portion. FIG. 15B is a schematic explanatory diagram illustrating an example of a formation mechanism of nanohole array pairs when anodizing is performed with the width of the land portion being twice that of the groove portion. FIG. 16A is a schematic explanatory diagram showing an example of a nanohole array pair formation mechanism when anodizing is performed with the width of the land portion being 1.6 times the width of the groove portion. FIG. 16B is a schematic explanatory diagram illustrating an example of a nanohole array pair formation mechanism when anodizing is performed by setting the width of the land portion to 1.6 times the width of the groove portion. FIG. 17 is a schematic explanatory view showing an example of a magnetic material filling step in an example of the method for producing a magnetic recording medium of the present invention.

Explanation of symbols

20..Intermediate layer (nonmagnetic layer)
30 ... Recording layer 52 ... Aluminum substrate 54 ... Ni stamper mold 56 ... Uneven pattern 58 ... Nanohole array 58A ... Nanohole array 58a ... Nanohole 59 ... Cobalt (magnetic material)
100: Writing / reading head (single pole head)
DESCRIPTION OF SYMBOLS 102 ... Main magnetic pole 104 ... Second half part 110 ... Substrate 120 ... Base electrode layer 130 ... Anodized alumina layer 140 ... Ferromagnetic layer G ... Groove part L ... ... Land part

Claims (17)

  A nanohole structure characterized in that a nanohole array in which nanoholes are arranged one-dimensionally on a metal substrate is formed as a pair of nanohole arrays at regular intervals.   2. The nanohole structure according to claim 1, wherein an interval between nanohole arrays in one nanohole array pair is substantially the same as an interval between the one nanohole array pair and the adjacent nanohole array pair.   The distance between one nanohole array pair and a nanohole array pair adjacent to the one nanohole array pair is greater than and less than twice the distance between nanohole arrays in the one nanohole array pair. Nanohole structure.   The distance between one nanohole array pair and the adjacent nanohole array pair is larger than the distance between nanohole arrays in the one nanohole array pair and 1.8 times or less. The nanohole structure according to 1.   The nanohole structure according to any one of claims 1 to 4, wherein the metal substrate has a disk shape, and the nanohole array pair is located in at least one of a concentric circle shape and a spiral shape. A method for producing the nanohole structure according to any one of claims 1 to 5,
A nanohole formation processing step of forming a nanohole array pair by forming a groove portion and a land portion on a metal substrate and then anodizing with a voltage given by either of the following formula (1) and the following formula (2) A method for producing a nanohole structure, comprising:
Groove width (nm) / A (nm / V) (1)
Groove width (nm) / (√3 / 2) / A (nm / V) (2)
However, in said Formula (1) and said Formula (2), A is 2.0-3.0.   The method for producing a nanohole structure according to claim 6, wherein A in Formula (1) and Formula (2) is 2.5 ± 0.2.   The method for producing a nanohole structure according to any one of claims 6 to 7, wherein the groove part and the land part are formed by forming a concave line on the metal substrate.   The method for producing a nanohole structure according to any one of claims 6 to 8, wherein a width of the land portion is substantially the same as a width of the groove portion.   The method for producing a nanohole structure according to any one of claims 6 to 8, wherein the width of the land portion is larger than the width of the groove portion and less than twice.   The method for producing a nanohole structure according to claim 10, wherein the width of the land portion is larger than the width of the groove portion and 1.8 times or less. On the substrate, has a porous layer in which a plurality of nanoholes are formed in a direction substantially orthogonal to the substrate surface, and has a magnetic material inside the nanoholes,
A magnetic recording body, wherein the porous layer is a nanohole structure according to any one of claims 1 to 5.   The magnetic recording medium according to claim 12, wherein the nanohole has a soft magnetic layer and a ferromagnetic layer in this order from the substrate side, and the thickness of the ferromagnetic layer is equal to or less than the thickness of the soft magnetic layer.   The magnetic recording medium according to claim 12, further comprising a soft magnetic underlayer between the substrate and the porous layer. A method for producing a magnetic recording medium according to any one of claims 12 to 14,
After forming a metal layer on the substrate, a groove portion and a land portion are formed in the metal layer, and anodized with a voltage given by either of the following formula (1) and the following formula (2), A nanohole structure forming step of forming a nanohole structure by forming a plurality of nanohole array pairs in a direction substantially orthogonal to the substrate surface; and a magnetic material filling step of filling a magnetic material inside the nanoholes in the nanohole array pair; A method for manufacturing a magnetic recording medium, comprising:
Groove width (nm) / A (nm / V) (1)
Groove width (nm) / (√3 / 2) / A (nm / V) (2)
However, in said Formula (1) and said Formula (2), A is 2.0-3.0.   The method of manufacturing a magnetic recording medium according to claim 15, wherein the width of the land portion is larger than the width of the groove portion and less than twice.   The method of manufacturing a magnetic recording medium according to claim 15, wherein the width of the land portion is larger than the width of the groove portion and 1.8 times or less.