JP4871809B2 - Patterned media, method for manufacturing magnetic recording medium, and method for manufacturing substrate - Google Patents

Description

  The present invention relates to patterned media. The present invention also relates to a method for manufacturing a magnetic recording medium, and more particularly to a magnetic recording medium used as an information recording medium. The present invention also relates to a method for manufacturing a substrate.

With the dramatic increase in information processing amount in recent years, a large increase in capacity is required for magnetic recording media widely used as information recording media. In particular, hard disks have been greatly increased in capacity and recording density, supported by advances in microfabrication technology and signal processing technology. However, in recent years, the recording density of about 200 Gbit / in ^2, which has been a physical limit due to the problem of thermal fluctuation, is approaching in the conventional in-plane recording method in which magnetization is recorded in the in-plane direction of the substrate. Was also moderate. Recently, with the commercialization of a so-called perpendicular recording type hard disk, which is considered to be strong against the problem of thermal fluctuation, a method of recording magnetization in the direction perpendicular to the substrate, further improvement in recording density will continue. It is expected to be realized.

  However, an increase in noise is a big problem for further higher density in the future. That is, as recording bits become finer due to higher recording density, there is a problem that variations in the shape and size of magnetic particles cause noise and deteriorate recording and reproduction characteristics. In order to solve this, it is considered that reduction of exchange interaction between adjacent magnetic particles, miniaturization of the size of the magnetic particles, and uniformity of the shape are effective.

In particular, by controlling the arrangement of magnetic particles using microfabrication technology, regularly arranged magnetic particles having the same shape and size are called patterned media, and the recording density is 1 Tbit / in ² grade. Attention has been focused on the possibility of realizing an ultra-high density recording medium having

In order to produce such a patterned medium, there is a method (Patent Document 1) in which a magnetic layer is subjected to processing such as etching to produce regularly arranged magnetic particles having a uniform shape and size.
Japanese Patent Laid-Open No. 9-297918

However, etching the magnetic layer may damage the magnetic layer.
Therefore, an object of the present invention is to provide a novel patterned medium that does not require the magnetic layer to be separated by etching, and a method for manufacturing the magnetic recording medium. Magnetic recording media include magnetic recording layers used in so-called hard disk drives and magnetic memories such as quantum dots.

  The patterned medium according to the first aspect of the present invention is a patterned medium including a magnetic recording layer, wherein a plurality of convex members are provided in an array on a substrate, and the convex members are The magnetic recording has a shape in which a cross-sectional area in a plane parallel to the substrate decreases toward the substrate, and the upper surface portion of the convex member is not in contact with the adjacent upper surface portion. A layer is provided.

  According to a second aspect of the present invention, there is provided a method for producing a substrate, comprising: preparing a member having an underlayer and an anodized layer on a substrate in this order from the substrate side; and forming holes in the member by anodization. Forming and growing the oxide of the underlayer toward the outside of the member in the hole, expanding the hole diameter of the hole, and further anodizing the member having the hole diameter expanded And a step of further growing the oxide of the underlayer in the hole toward the outside of the member.

  According to a third aspect of the present invention, there is provided a method for producing a substrate, comprising: preparing a member having an oxide layer on a substrate via an intermediate layer; and forming grooves in the member so that side surfaces of the intermediate layer are exposed at a predetermined interval. Forming and anodizing so that a side surface of the intermediate layer swells, and embedding a filler in the groove to obtain a substrate having a shape portion tapered toward the substrate side. To do.

  According to a fourth aspect of the present invention, there is provided a substrate manufacturing method comprising: a step of disposing a layer made of a material whose volume is expanded by oxidation treatment on a substrate; and a plurality of tapering shapes in the direction away from the substrate on the layer. Providing a projecting member, and oxidizing the layer to grow an oxide of the material between the projecting members.

  According to a fifth aspect of the present invention, there is provided a method of manufacturing a magnetic recording medium, comprising: forming a plurality of convex members having a shape tapered toward a substrate on the substrate using an imprint method; It has the process of providing the magnetic layer for magnetic recording on the upper surface side of a convex-shaped member, It is characterized by the above-mentioned.

  According to a sixth aspect of the present invention, there is provided a method of manufacturing a magnetic recording medium, comprising: providing a base layer on a substrate and a porous film on the base layer; and an oxide of the base layer from the bottom of the porous film. Growing in a direction perpendicular to the substrate, removing at least a part of the porous film to obtain a protrusion made of the underlayer and the oxide of the underlayer on the substrate, and the protrusion It includes a step of arranging a magnetic body on the top of the object.

According to the present invention, a novel patterned medium, a method for manufacturing a magnetic recording medium, and the like are provided.
In addition, according to the present invention, a spatially separated magnetic film can be obtained.

  In addition, if the shape of the said convex member is made into a reverse taper shape so that it may mention later, it can reduce that a magnetic material adheres to the side surface of the said convex member.

The present invention will be described in detail below.
The patterned medium according to the present invention relates to a patterned medium including a magnetic recording layer. Specifically, a plurality of convex members are provided in an array on the substrate, and the convex members have a shape in which a cross-sectional area in a plane parallel to the substrate decreases toward the substrate. ing. Further, the magnetic recording layer is provided on the upper surface portion of the convex member so as not to contact between the adjacent upper surface portions.

It is preferable that the convex member is made of an oxide, a resin, or a metal.
The convex member preferably has a height of less than 30 nm.
The convex member preferably has a height of 5 nm to 29 nm.

It is preferable that the heights between the adjacent convex members are aligned so that the difference in height between the upper surface portions of the adjacent convex members is less than 5 nm.
It is preferable that the magnetic recording layer is provided on the upper surface portion of the convex member via an alignment film.

It is preferable that a soft magnetic layer is provided between the substrate and the convex member.
It is preferable that the magnetic recording layer is not provided on a side surface of the convex member.
It is preferable that a material constituting the magnetic recording layer is provided on the substrate between the plurality of convex members.

The substrate manufacturing method according to the present invention includes the following steps.
(A) First, a step of preparing a member having an underlayer and an anodized layer on a substrate in this order from the substrate side;
(B) forming a hole in the member by anodic oxidation, and growing the oxide of the base layer in the hole toward the outside of the member;
(C) The step of enlarging the hole diameter of the hole, the member subjected to the enlargement process of the hole diameter is further anodized, and the oxide of the underlayer is further grown in the hole toward the outside of the member. Process.

It is preferable to repeat the generation of the oxide of the underlayer by the anodizing treatment and the treatment for expanding the pore diameter.
As for the shape of the oxide of the foundation layer grown in the hole, it is preferable that the cross-sectional area of the oxide in a direction parallel to the substrate plane is smaller toward the substrate.

The shape of the oxide is preferably an inversely tapered shape.
It is preferable to provide a magnetic film on the oxide.
Removing or anodizing the anodized layer present between the oxides of the plurality of underlying layers formed on the substrate after or before providing the magnetic film on the oxide; preferable.

  The substrate manufacturing method according to the present invention includes a step of preparing a member having an oxide layer on the substrate via an intermediate layer, and forming grooves in the member so that side surfaces of the intermediate layer are exposed at predetermined intervals. The process of carrying out. And a step of anodizing the side surface of the intermediate layer so as to swell, and a step of obtaining a base body having a tapered shape toward the substrate side by embedding a filler in the groove. .

It is preferable that the member has a first oxide layer, the intermediate layer, and a second oxide layer as the oxide layer on the substrate from the substrate side.
Furthermore, the method for manufacturing a substrate according to the present invention includes a step of disposing a layer made of a material whose volume is expanded by an oxidation treatment on a substrate, and a plurality of protrusions having a tapered shape in a direction away from the substrate on the layer. Providing a step-like member. And it has the process of growing the oxide of the said material between this convex-shaped member by oxidizing the said layer, It is characterized by the above-mentioned.

The convex member on the substrate is preferably formed by an imprint method.
After growing the oxide of the material, it is preferable to stack a magnetic film on the oxide.

It is preferable to remove the convex member after laminating the magnetic films.
It is preferable to form the magnetic film on the oxide after removing the convex member.
A method for manufacturing a magnetic recording medium according to the present invention is a method for manufacturing a magnetic recording medium, and includes the following steps. A step of forming a plurality of convex members having a shape tapered toward the substrate side on the substrate by using an imprint method; and a magnetic layer for magnetic recording on an upper surface side of the convex member. It is a process of providing.

It is preferable to provide the magnetic layer on the convex member via an alignment layer.
The method for producing a magnetic recording medium according to the present invention includes the following steps (a) to (d).
(A) a step of providing a base layer on the substrate and a porous film on the base layer (b) a step of growing an oxide of the base layer in a direction perpendicular to the substrate from the bottom of the porous film (C) A step of removing at least a part of the porous film to obtain a protrusion made of the underlayer and the oxide of the underlayer on the substrate (d) A magnetic material is disposed on the protrusion. Step The base layer is preferably a layer containing at least one element selected from Ti, Zr, Hf, Nb, Ta, Mo, and W.

The step of providing the porous film is preferably a step of forming an anodized layer on the underlayer and a step of anodizing the anodized layer to form the porous film.
The step of providing the porous membrane is preferably a step of disposing a phase separation membrane on the underlayer and a step of removing one phase of the phase separation membrane to form the porous membrane.

Furthermore, the following manufacturing methods are also included in the present invention.
A method of manufacturing a magnetic recording medium for solving the above-described problems includes the following steps (a) to (e).
(A) A step of disposing an underlayer on the substrate and an anodized layer on the underlayer (b) A step of anodizing the anodized layer to form a porous film (c) of the porous film A step of growing an oxide containing an element constituting the underlayer on the bottom in a direction perpendicular to the substrate; (d) a protrusion comprising the underlayer and the oxide on the substrate by removing the porous film; (E) a step of disposing a magnetic body on top of the protrusion

A patterned medium for solving the above problem is a patterned medium including a magnetic recording layer, and has the following characteristics.
Specifically, a plurality of convex members are provided in an array on the substrate, and the convex members have a shape in which a cross-sectional area in a plane parallel to the substrate decreases toward the substrate. ing. Further, the magnetic recording layer is provided on the upper surface portion of the convex member so as not to contact between the adjacent upper surface portions.

A method of manufacturing a substrate for solving the above-described problems includes the following steps (a) to (c).
(A) preparing a member having a base layer and an anodized layer on the substrate in this order from the substrate side;
(B) forming a hole in the member by anodic oxidation, and growing the oxide of the base layer in the hole toward the outside of the member;
(C) The step of enlarging the hole diameter of the hole, the member subjected to the enlargement process of the hole diameter is further anodized, and the oxide of the underlayer is further grown in the hole toward the outside of the member. Process

Moreover, the manufacturing method of the base | substrate for solving said subject has the process of the following (a) to (c), It is characterized by the above-mentioned.
(A) preparing a member having an oxide layer on the substrate via an intermediate layer;
(B) forming a groove in the member so that the side surface of the intermediate layer is exposed at a predetermined interval, and anodizing so that the side surface of the intermediate layer swells;
(C) A step of obtaining a base body having a shape portion tapered toward the substrate side by embedding a filler in the groove.

Furthermore, a method for manufacturing a substrate for solving the above-described problems includes the following steps (a) to (c).
(A) a step of disposing a layer made of a material whose volume is expanded by an oxidation treatment on a substrate;
(B) providing a plurality of convex members having a tapered shape in a direction away from the substrate on the layer;
(C) Oxidizing the layer to grow an oxide of the material between the convex members

In addition, a method of manufacturing a magnetic recording medium for solving the above-described problems includes the following steps (a) and (b).
(A) A method of manufacturing a magnetic recording medium, the step of forming a plurality of convex members having a shape tapered toward the substrate side on the substrate using an imprint method;
(B) Step of providing a magnetic layer for magnetic recording on the upper surface side of the convex member An embodiment of the present invention will be described below.

(Embodiment 1)
3 is an embodiment based on patterned media.
The patterned medium including the magnetic recording layer according to this embodiment has the following characteristics.

  First, a plurality of convex members are provided in an array on the substrate, and the convex member has a shape in which a cross-sectional area in a plane parallel to the substrate decreases toward the substrate (reverse tapered shape). )have. Further, the magnetic recording layer is provided on the upper surface portion of the convex member so as not to contact between the adjacent upper surface portions.

  This will be specifically described with reference to FIG. In this figure, 2990 is a substrate, 2991 is a convex member, and 2992 is a magnetic film on the member. If necessary, other layers for various purposes may be interposed between the substrate and the convex member, or between the member and the magnetic film. Reference numeral 2993 denotes an upper surface portion of the convex member 2992. The array-like arrangement is a concept including not only a case where the convex members are arranged at equal intervals in all the regions on the substrate but also an arrangement in which only some regions on the substrate are arranged. is there.

With such a configuration, the magnetic recording layer can be spatially separated, and the reverse taper shape can be used to make it difficult for the magnetic film to adhere to the side surface of the convex portion.
Here, the material of the convex member is not particularly limited, but a metal, an oxide, or a resin (such as photo-curing, thermosetting, or thermoplastic resin) is preferably used. As the oxide, an oxide of a metal or an alloy that is oxidized by an anodizing treatment is preferably used.

  It is desirable that the convex member has a height of less than 30 nm. In particular, when a soft magnetic layer is provided under the member and on the substrate, the height of the member should be low in order to effectively utilize the high magnetic permeability of the soft magnetic layer. . Although the minimum of the height of the said convex-shaped member is not specifically limited, It is good that it is 5 nm or more and 29 nm or less in height.

Moreover, it is desirable that the heights between the adjacent convex-shaped members are aligned so that the difference in height between the upper surface portions of the adjacent convex-shaped members is less than 5 nm.
The magnetic recording layer may be provided on the upper surface portion of the convex member via an orientation film (a film for orienting the magnetic layer thereon). The alignment film is, for example, MgO or platinum.

A soft magnetic layer can be provided between the substrate and the convex member.
Although it is preferable that the magnetic recording layer is not provided on the side surface of the convex member having a reverse taper, the invention according to the present embodiment is not necessarily limited to this state.

Moreover, the material which comprises the said magnetic-recording layer can also be provided on the said board | substrate between the said some convex-shaped members. It can be removed if necessary.
The angle 2995 of the reverse taper portion is in the range of 45 degrees to 85 degrees, and preferably in the range of 60 degrees to 80 degrees.

In addition, when the magnetic film 2992 is formed by a sputtering method or the like, it is desirable that the constituent material of the magnetic film does not adhere to the side surface of the convex portion 2991.
However, the invention according to the present embodiment does not exclude the case where the magnetic film is attached between the convex portions 2991 2994.

As will be described later, this convex member is produced using, for example, an optical imprint method or a thermal imprint method.
A patterned medium in which convex portions having an inversely tapered shape are arranged at a predetermined period or interval as in the present invention is extremely useful.

This patterned medium can be used as a magnetic recording medium (such as a hard disk medium or a magnetic memory composed of quantum dots).
Of course, it is possible to fill the gaps between the convex portions with a nonmagnetic material as necessary (not shown).

(Embodiment 2)
This is an embodiment based on FIG. 12 and FIG. 13.
The invention relating to the method for manufacturing a substrate according to the present embodiment has the following features.

  First, a member having an underlayer and an anodized layer in this order from the substrate side is prepared on the substrate. Then, holes are formed in the member by anodizing treatment, and the oxide of the base layer is grown in the holes toward the outside of the member. Thereafter, the hole diameter of the hole is increased, and the member subjected to the expansion process is further anodized. By this anodizing treatment, the oxide of the underlayer can be further grown in the hole toward the outside of the member.

By such a method, strictly, an inversely tapered oxide tapering in a step shape can be arranged on the substrate.
Here, a step-like side surface can be realized by repeating the generation of the oxide of the base layer by the anodizing treatment and the treatment for expanding the pore diameter.
In addition, it can be said that the shape of the oxide of the underlayer grown in the hole has a cross-sectional area of the oxide in a direction parallel to the substrate plane that decreases toward the substrate.

It can also be said that the shape of the oxide has a reverse taper shape. A magnetic film can be provided on the oxide via an alignment film as necessary.
Removing or anodizing the anodized layer present between the oxides of the plurality of underlying layers formed on the substrate after or before providing the magnetic film on the oxide; it can.

(Embodiment 3)
It is embodiment based on FIG.
The substrate manufacturing method according to the present embodiment has the following characteristics. First, a member having an oxide layer is prepared on a substrate via an intermediate layer. Then, a groove is formed in the member so that the side surface of the intermediate layer is exposed at a predetermined interval, and anodization is performed so that the side surface of the intermediate layer swells. Thereafter, by filling the groove with a filler, a substrate having a shape portion that is tapered toward the substrate can be manufactured.

  Here, the member may be configured to have the first oxide layer, the intermediate layer, and the second oxide layer as the oxide layer on the substrate from the substrate side. Good.

(Embodiment 4)
FIG. 17 is an embodiment based on FIGS.

  The substrate manufacturing method according to the present embodiment has the following characteristics. First, a layer made of a material whose volume is expanded by oxidation treatment is disposed on a substrate, and a plurality of convex members having a tapered shape in a direction away from the substrate are provided on the layer. And if necessary, after performing the process which exposes the said layer between the said convex-shaped members, the oxide of the said material is grown between these convex-shaped members by oxidizing the said layer. By such a method, an oxide can be grown along the shape of the convex member. As a result, a base body in which a plurality of members having a reverse taper shape are arranged on the substrate is manufactured.

  Here, the convex member on the substrate can be formed by a so-called imprint method. As the imprint method, thermal imprint, optical imprint, and soft imprint can also be applied. Of course, the formation of the convex member is not limited to the imprint method, and lithography or the like can also be used.

In addition, after the oxide of the material is grown, a magnetic film can be laminated on the oxide. If necessary, a magnetic film is laminated via an alignment film.
Note that the convex member can be removed after the magnetic film is laminated, or the magnetic film can be formed on the oxide after the convex member is removed.

(Embodiment 5)
FIG. 19 is an embodiment based on FIGS.
The method for manufacturing a magnetic recording medium according to the present embodiment is a method for manufacturing a magnetic recording medium, and has the following characteristics. Specifically, a plurality of convex members (also referred to as reverse tapered shapes) having a shape tapered toward the substrate side are formed on the substrate by using an imprint method. The arrangement of the convex members may be dot-shaped, line-shaped, or a mixture thereof, and is not particularly limited.

  Then, a magnetic layer for magnetic recording is provided on the upper surface side of the convex member via an alignment film as necessary. The convex member (for example, can be formed by curing a photocurable or thermosetting resin) can be formed by a so-called imprint method. As the imprint method, thermal imprint, optical imprint, and soft imprint can also be applied. Depending on the shape of the mold (template) used for imprinting, it may be difficult to release the mold from the resin cured along the mold pattern. In such a case, if necessary, a release agent can be interposed between the mold and the resin, or the resin can be released from the mold while heating. In particular, the mold can be released using the elasticity of the resin. In addition, it is described in Unexamined-Japanese-Patent No. 2004-335774 about producing reverse taper shape by the imprint method itself.

  Specifically, “First, a resist layer (for example, a layer made of polymethylglutarimide, which is a polyimide-based thermoplastic resin) is formed on a substrate. The resist layer is formed on the substrate using a spin coater or the like. Polymethylglutarimide is applied to a film thickness of 0.4 μm, and then the substrate on which the polymethylglutarimide film is formed is heated on a hot plate heated to 150 ° C. for 60 seconds and dried. Next, a mold having a convex portion corresponding to the pattern to be formed is pressed from the resist layer side while the substrate on which the resist layer is formed is heated on a hot plate. As conditions, it is preferable to set the heating temperature to 130 ° C., the pressing pressure to 100 MPa, and the pressing time to 5 minutes. In addition, the shape of the convex portion is set to a shape in which the tip of the convex portion reaches the substrate in consideration of the resist film thickness. Next, the mold 3 is peeled off from the resist layer after being cooled to room temperature, and the resist layer pressed by the mold is a side wall of a recess following the convex part having a reverse tapered side wall of the mold. Is formed in a reverse tapered shape. " The technique described in the publication can also be applied to the invention according to the present embodiment.

  Further, the magnetic layer can be provided on the convex member via an orientation layer. After a magnetic layer is formed on the convex member, a groove between the members can be filled, and a planarizing layer or the like can be laminated on the magnetic layer.

  Note that the mold shown in FIG. 17 is manufactured, for example, as follows. That is, it is obtained by forming a convex portion having the same shape as the mold concave portion 114 on a metal substrate by photolithography and etching, and pouring and curing an elastic material such as polydimethylsiloxane on the convex portion.

  As described above in Embodiments 1 to 6, by providing a magnetic recording layer on the upper surface side of a convex member having a cross-sectional shape that becomes narrower toward the substrate side, the magnetic recording layers are separated from each other. It can be spatially separated. In particular, the reverse taper shape makes it difficult to attach the magnetic film to the side wall of the member, so that the noise and the effects caused by the magnetic film can be reduced.

  When a columnar structure based on the orientation of crystal grains is used as the base convex structure, the base film becomes thick to form a sufficiently isolated columnar structure, and there is a possibility that no effect can be expected when a soft magnetic layer is inserted. In addition, there are variations in the height of the crystal grains, which may make it difficult to fly the magnetic head. In addition, the grain size of the crystal grains themselves varies, and it seems difficult to apply to patterned media in which 1-bit recording is performed on one crystal grain. Therefore, the invention according to this embodiment is extremely useful. In the above-described technique, it is difficult to form a tapered shape having a uniform shape between the convex members with respect to the reverse tapered shape itself. However, according to the above-described invention according to the present embodiment, it is possible to arrange reverse tapered structures.

  In addition, as long as there is no contradiction, the description of each embodiment can mutually supplement the description of each embodiment, and the Example demonstrated below can also be suitably applied to each embodiment.

Note that the size and density of the inversely tapered member described in the first to fifth embodiments and the inclination of the tapered portion are not particularly limited.
As an example, the size of the convex member is 20 nm to 100 nm in the vertical direction and 10 nm to 80 nm in the horizontal direction when viewed as a top view in the substrate direction.

The density of the convex members is, for example, an average interval of 15 nm to 150 nm.
The inclination (angle) of the reverse taper portion is preferably 25 ° ≦ θ <90 ° when the angle formed by the upper surface of the convex member and the taper portion is θ, and it is difficult to form a magnetic film on the side wall. 25 ° ≦ θ ≦ 70 °. More preferably, it is in the range of 45 to 80 degrees, and preferably in the range of 60 to 80 degrees.

  Furthermore, the technical matters described in the sixth embodiment can be appropriately applied in the first to fifth embodiments as long as there is no technical contradiction.

(Sixth embodiment)
FIG. 12 is an embodiment based on FIGS.

The method for manufacturing a magnetic recording medium according to this embodiment includes the following steps (a) to (c).
(A) a step of providing a base layer on the substrate and a porous film on the base layer (b) a step of growing an oxide of the base layer in a direction perpendicular to the substrate from the bottom of the porous film (C) a step of removing at least a part of the porous film to obtain a protrusion made of the underlayer and the oxide of the underlayer on the substrate; and a step of disposing a magnetic body on the protrusion A magnetic recording medium is manufactured.

Here, the step of providing the porous film is realized by a step of forming an anodic oxidation layer on the underlayer and a step of anodizing the anodic oxidation layer to form the porous film. The
Or the process of providing the said porous membrane is implement | achieved by the process of arrange | positioning a phase-separation film on the said base layer, and the process of removing one phase of this phase-separation film, and setting it as the said porous film. This phase separation membrane will be described later.

It is preferable that the oxide of the underlayer is grown in a direction perpendicular to the substrate at the bottom of the porous film at the hole position, or at the bottom of the porous film at the hole position and the bottom of the hole.
The underlayer is preferably a layer containing at least one element selected from Ti, Zr, Hf, Nb, Ta, Mo, and W.

It is preferable to perform the step of growing the oxide of the base layer in the direction perpendicular to the substrate at the bottom of the pores of the porous film by anodic oxidation.
The electrolytic solution used for the anodic oxidation is preferably an aqueous ammonium borate solution, an ammonium tartrate solution or an aqueous ammonium citrate solution.

  After the step of anodizing in the electrolyte and growing the oxide of the underlayer perpendicular to the substrate at the bottom of the pores of the porous film, the porous film or the porous film and the underlayer are oxidized It is preferable to include a step of polishing the surface of the object.

The step of removing the porous film is preferably performed by wet etching.
The oxide of the underlayer is preferably heat-treated in an oxidizing atmosphere.
It is preferable that the step of disposing the magnetic body on the protrusion is performed by a film forming method in which film forming particles having directivity with respect to the substrate fly.

It is preferable to include a step of disposing an intermediate layer between the protrusion and the magnetic body.
First, the method for manufacturing a magnetic recording medium according to this embodiment includes the following steps.
A step of disposing an underlayer on the substrate and an anodized layer on the underlayer, a step of anodizing the anodized layer to form a porous film, and an underlayer on the bottom of the porous film In which the oxide is grown in a direction perpendicular to the substrate. These processes are referred to as “anodic oxidation processes”.

  Further, a step of removing the porous film to obtain a protrusion made of the base layer and the oxide of the base layer on the substrate (referred to as a “step of obtaining a protrusion”), and a magnetic layer on the top of the protrusion. Including a step of arranging a body (referred to as a “step of arranging a magnetic body”).

Here, the embodiment of the present invention will be described by dividing it into three steps of “1. anodic oxidation step”, “2. step of obtaining protrusions”, and “3. step of arranging magnetic body”.
(1. Anodizing process)
A sample is prepared in which a base layer is further formed on a substrate, and an anodized layer is further disposed thereon using a thin film forming method such as sputtering. As the underlayer, a material containing at least one element selected from Ti, Zr, Hf, Nb, Ta, Mo, and W is disposed. Further, as the anodized layer, Al or an alloy containing Al as a main component is disposed. This anodizing step can be performed in an electrolytic solution.

  Next, when the sample is anodized using an acidic aqueous solution such as phosphoric acid, oxalic acid, sulfuric acid or the like, a porous film 12 in which a large number of holes 10 grow in a direction perpendicular to the substrate 11 from the sample surface as shown in FIG. Is obtained. The structure of the porous film 12 is composed of a minute hole 10 and an oxide 13 of an anodic oxidation layer surrounding the minute hole 10, and in particular, the oxide layer formed at the bottom of the hole 10 is called a barrier layer 14. The thickness of the barrier layer 14 is empirically known to be the barrier layer thickness (nm) = 1.2 × V with respect to the anodic oxidation voltage V (Volt). In addition, the pores of the porous film are generated from random positions on the sample surface. However, if a small dent that is the starting point of anodization is prepared on the sample surface by electron beam drawing or nanoimprinting, the hole will start from the starting point. It occurs only from the position. That is, it is possible to obtain a porous film having pores regularly arranged according to the arrangement pattern of the depressions. At this time, the anodic oxidation voltage V (Volt) is set to an anodization voltage V such that the period of the regular arrangement (nm) = 2.5 × V, thereby obtaining a porous film having highly ordered pores. It is considered preferable.

  In order to obtain the porous film as described above, Al is generally used as the anodized film. This is because there is a material that forms a porous film by anodic oxidation even with materials other than Al, such as Si and Ti, but the verticality of the holes is not so good, hydrofluoric acid is used as an acidic aqueous solution, etc. This is because there are problems and difficulties. Further, the present inventors are alloys containing Al as a main component, and as long as they are Al alloys containing at least one element selected from Ti, Zr, Hf, Nb, Ta, Mo, and W, they are perpendicular to Al. It has been found that a porous film having pores with good properties can be formed. In this case, by alloying Al, it becomes possible to reduce the roughness of the film surface due to hillocks and grain boundaries, so when preparing a small dent to be the starting point of anodization on the sample surface This is a particularly effective means. The amount of element added to Al depends on the type of element to be added, but in order to form a porous film having pores with good perpendicularity as with Al, the amount should be generally in the range of 5 atomic% to 50 atomic%. preferable.

  By continuing the anodic oxidation, the porous film grows from the sample surface toward the substrate, and the porous film 22 grows until the bottom of the barrier layer 20 reaches the base layer 21 as shown in FIG. At this time, a material containing at least one element selected from Ti, Zr, Hf, Nb, Ta, Mo, and W is disposed as the material of the underlayer 21. Then, the present inventors have found that an oxide 23 containing an element constituting the underlayer grows from the underlayer 21 toward the hole 24 as shown in FIG. 3 on the bottom 27 of the porous film.

  Further, the state of FIG. 3 is further changed to an electrolytic solution that provides a barrier type anodic oxide film such as an aqueous solution of ammonium borate, an aqueous solution of ammonium tartrate, or an aqueous solution of ammonium citrate. By doing so, it is more preferable to grow the oxide layer 23 of the underlayer while filling the pores 24 of the porous film as shown in FIG.

(2. Step of obtaining protrusions)
Next, the process of removing the porous film obtained by anodic oxidation to obtain a protrusion will be described.
As shown in FIG. 3 and FIG. 4, wet etching is performed by immersing a sample in which an oxide of the underlayer is grown in an acid or alkali solution. At this time, using the difference in etching resistance between the oxide of the anodized layer and the oxide of the underlayer, only the oxide of the anodized layer is selectively dissolved and removed to oxidize the underlayer. Etching is performed so that the object remains as a protrusion. The oxide of the anodized layer is mainly made of alumina, which is an oxide of Al, and has very low resistance to alkali. Therefore, the oxide of the anodized layer can be easily removed by using NaOH, KOH, etc. it can. Further, depending on the material for forming the oxide of the underlayer, it may be difficult to selectively dissolve and remove only the oxide of the anodized layer. For example, when W is used as a base layer, there arises a problem that not only the oxide of the anodized layer but also the oxide of W is dissolved by acid or alkali. In such a case, it is possible to selectively dissolve and remove only the oxide of the anodized layer by performing wet etching after reducing the oxide of the underlying layer by heat treatment in vacuum or the like.

  That is, if a porous film having regularly arranged pores is formed in the anodic oxidation step, the regularly arranged projections made of the base layer 21 and the oxide of the base layer are formed on the substrate 26 as shown in FIG. A structure with 25 can be obtained.

The etching resistance between the alumina to be anodized and the oxide of the underlayer will be described in more detail.
Alumina formed by anodization is classified as γ-Al ₂ O ₃ as a crystallographic property. α-Al ₂ O ₃ is alumina with good crystallinity, whereas γ-Al ₂ O ₃ is alumina with poor crystallinity. The chemistry becomes very easily etched with acids and alkalis as crystallinity deteriorates. Therefore, γ-Al ₂ O ₃ is easily etched even with a weak acid such as phosphoric acid. The oxide of the underlayer is formed as a barrier type anodic oxide film, but the etching resistance to acid and alkali varies depending on the kind of element of the underlayer and the valence that the element in the oxide can take. For example, Ta oxide is insoluble in acid and has etching resistance against alkali. In addition, NbO composed of divalent Nb is soluble in acid alkali, but NbO ₂ and Nb ₂ O ₅ having high oxidation number are tetravalent and pentavalent. Is insoluble, and has characteristics such as improved etching resistance against alkali.

It is possible to form a protrusion by paying attention to the etching resistance of the oxide and further selecting the type, concentration and immersion time of the etching solution.
On the other hand, the following points have been reported in the case where a protruding oxide formed of a barrier type anodic oxide film capable of taking several kinds of valence oxides can take several kinds of valence oxides. That is, it has been reported that the oxide valence is different between the surface and the inside of the protrusion, and an oxide having a large valence is formed in the outer peripheral portion, but the oxidation number inside the protrusion is lowered. In addition, the etching resistance of the oxide is greatly affected by the inclusion of oxide based on the electrolyte during the anodic oxidation, crystal defects, and the influence of incorporation of bound water, etc. Also affects.

  Here, when heat treatment is performed in an oxidizing atmosphere after the creation of the barrier type anodization, impurities such as bonding water in the underlayer oxide are removed, and further, an oxide with a high oxidation number is obtained, and etching resistance is increased. . By performing the heat treatment step in an oxidizing atmosphere, the strength of the protrusion is improved, and the magnetic recording medium using the protrusion structure is more desirable.

The higher the temperature of the heat treatment, the higher the etching resistance of the oxide, but alumina, which is a porous film to be removed, gradually improves its crystallinity from γ-Al ₂ O ₃ and dissolves in acid alkali. It becomes difficult. Further, a perpendicular magnetic recording medium is formed by providing a soft magnetic layer between the base layer 21 and the substrate in FIG. 2, but it is necessary to consider deterioration of the characteristics of the soft magnetic layer due to heating. From the above conditions, the heating temperature is 200 ° C. or higher and 400 ° C. or lower, preferably 250 ° C. or higher and 350 ° C. or lower. When the temperature is lower than 200 ° C., the effect of the heat treatment does not sufficiently contribute, and when the temperature is higher than 400 ° C., the soft magnetic characteristics deteriorate.

  The heat treatment may be performed either after the barrier type anodic oxidation or after the etching of alumina. However, the alumina etching conditions to be selected differ depending on which process is taken.

  When the oxide of the base layer is grown in the state of FIG. 3 in “1. Anodizing step”, the shape of the protrusion 25 obtained is a columnar shape. The height is determined by the thickness of the barrier layer at the time of anodization, and the diameter is determined by the pore diameter of the porous film formed by anodization. Therefore, all protrusions have a uniform height and diameter.

  On the other hand, when the oxide of the underlayer is grown to the inside of the pores of the porous film in the state shown in FIG. 4 in “1. Anodizing step”, the height of the protrusion 25 obtained is the oxidation of the underlayer. It is determined by the anodic oxidation voltage when an object is grown inside the pores of the porous film. The diameter is determined by the pore diameter of the porous coating when the oxide of the underlayer is grown inside the pores of the porous coating. For this reason, if the porous film is wet-etched with phosphoric acid or the like before the oxide of the underlayer is grown inside the pores of the porous film and the hole diameter is widened, protrusions having a large diameter may be obtained. It becomes possible. Furthermore, if the sample surface is polished and flattened before removing the porous coating, it is possible and preferable to obtain a projection 25 having a flatter upper surface. Projections grown in a direction perpendicular to the main surface of the substrate are suitable for applications such as magnetic recording media. The vertical direction here refers to a state in which the bottom of the protruding portion and the tip of the protruding portion appear to overlap each other when observed from above, and the other portion is in a state in which the main surface of the substrate can be observed. Except for the state in which the tip of the protrusion covers the bottom of the other protrusion.

(3. Step of arranging magnetic material)
Next, a recording layer is formed on the concavo-convex structure having the base layer 21 and the regularly arranged protrusions 25 made of an oxide containing an element constituting the base layer on the substrate 26 as shown in FIG. A process for depositing a magnetic material will be described.

  The magnetic material to be the recording layer is formed so as to be disposed on the top of the regularly arranged protrusions 25. At this time, it is desirable to set the state as shown in FIG. 6 so that the concave portions between the protrusions are not blocked by the magnetic body disposed on the protrusions 25. For this reason, it is preferable to form the magnetic material by a film having directivity that causes film formation particles to fly from a certain direction with respect to the substrate, for example, a film having directivity in a direction perpendicular to the substrate. A membrane process is conceivable. Specifically, in the case of sputtering, the directivity of sputtered particles that fly to the sample, such as lowering the gas pressure during sputtering, increasing the distance between the substrate and the sample, or placing a collimator between the target and the sample. It is effective to improve.

  Further, as shown in FIG. 6, a magnetic material 29 may be formed on the underlayer 21 that is the bottom of the concave portion. However, the protrusion 25 causes the magnetic material 28 serving as a recording portion to be spatially magnetized. It is also divided. Therefore, it is possible to obtain a patterned medium in which the magnetic body 28 disposed on the protrusion 25 is a recording portion.

As the magnetic material, the following materials can be used for the perpendicular recording system.
For example, it is Co of [Co / M] (M = Pt, Pd) multilayer film, hcp (hexagonal close-packed lattice) structure with the c-axis oriented in the direction perpendicular to the substrate. Alternatively, it is a material having uniaxial magnetic anisotropy in the direction perpendicular to the film surface, such as Lt ordered MPt or MPd (M = Co, Fe) whose c-axis is oriented in the direction perpendicular to the substrate.

  If a magnetic material with crystal orientation such as Co, MPt, or MPd (M = Co, Fe) is required, the orientation between the upper part of the protrusion and the magnetic material as shown in FIG. What is necessary is just to arrange | position the intermediate | middle layer 30 for the purpose of control as needed.

  As described above, recording is performed on the top of the regularly arranged projections according to the three steps of “1. anodizing step”, “2. step of obtaining projections”, and “3. step of arranging magnetic material”. A patterned medium in which a magnetic material to be a layer is arranged is produced.

(Phase separation membrane)
A phase separation film is a film formed by growing silicon so as to surround columnar aluminum when a film is formed on a substrate by sputtering using a target material made of aluminum and silicon.

By removing one of the phases constituting the phase separation membrane, a porous membrane can be obtained.
The phase separation film is a structure represented by Al—Si or Al—Ge system, and the Al cylinder stands in the vertical direction of the substrate, and its matrix is formed of α-Si or α-Ge. It is characterized by being. The phase separation membrane is described in, for example, Japanese Patent Application Laid-Open No. 2004-223695.

For example, consider a case where a phase separation film 9910 is provided on a base layer 9900 as shown in FIG.
Only the Al cylinder portion 9912 can be selectively etched with an acid / alkali such as ammonia water, concentrated sulfuric acid, phosphoric acid or the like, and a porous film can be obtained by this means. Reference numeral 9913 denotes a silicon region surrounding the aluminum cylinder (FIGS. 19A and 19B).

  Further, after the aluminum cylinder is removed by etching (FIG. 19B), it is anodized (FIG. 19C) while immersed in an aqueous solution of ammonium borate, ammonium tartrate, ammonium citrate or the like. By doing so, it is possible to grow an oxide 9960 such as Ti, Zr, Hf, Nb, Ta, Mo, and W forming the underlayer in the pores of the porous film 9950.

  Thereafter, the grown oxide protrusions 9960 can be obtained by selectively etching only the material constituting the porous film 9950 with a sodium hydroxide aqueous solution or a hydrogen peroxide solution. FIG. 19D shows a case where a part of the porous film 9950 is left in the thickness direction. Of course, if necessary, the porous membrane 9950 can be entirely removed.

Examples of the present invention will be described below.
Example 1
The present embodiment relates to obtaining a concavo-convex structure having protrusions regularly arranged by anodic oxidation, and disposing a magnetic body on top of the protrusion.

A sample was prepared by sputtering 5 nm of Ti serving as an underlayer on a Si substrate and further depositing AlTi containing 10 atomic% of Ti on the Si substrate by 100 nm sputtering.
Next, aluminum alkoxide was applied to the sample surface with a thickness of 20 nm by spin coating. Subsequently, the sample was baked at 90 ° C. for 20 minutes, and then a depression serving as an anodic oxidation starting point was transferred to the alkoxide surface by nanoimprinting. In this example, protrusions with a height of 15 nm were pressed onto a surface of the alkoxide by pressing a mold having a triangular lattice arrangement at an interval of 50 nm against the alkoxide surface.

  Thereafter, when a plurality of arbitrary locations on the alkoxide surface were scanned with an AFM (atomic force microscope), the mold protrusions were transferred to the alkoxide surface as depressions of about 5 nm.

  Further, the sample was treated by ashing using ultraviolet rays and ozone at 180 ° C. for 10 minutes, thereby removing the polymer portion in the alkoxide and simultaneously proceeding the oxidation of the aluminum portion to oxidize the alkoxide layer.

  Thereafter, anodization was performed at an applied voltage of 20 V in a 0.3 mol / L sulfuric acid aqueous solution having a bath temperature of 16 ° C. The oxidized alkoxide layer and aluminum layer were anodized all together. By observing the anodized sample with an FE-SEM (field emission scanning electron microscope), it was confirmed that a porous film having a triangular lattice arrangement was formed in the same manner as the pattern of the protrusions on the mold.

Further, anodic oxidation was continued until the bottom of the barrier layer reached the underlayer, whereby a Ti oxide as the underlayer was grown from the underlayer toward the hole.
Next, the porous film was removed by immersing the sample in a 0.1 mol / L NaOH aqueous solution having a bath temperature of 23 ° C. for 5 minutes. As a result, a concavo-convex structure remained as protrusions in which the oxide of the underlayer was arranged in a triangular lattice at intervals of 50 nm. The size and shape of the protrusions were cylindrical with a height of about 25 nm and a diameter of about 20 nm.

  Next, a film of a magnetic material was formed on the obtained concavo-convex structure, and the magnetic material was disposed on the top of the protrusion. Film formation of the magnetic material was performed by sputtering, and the distance between the target and the sample was 15 cm, and power of DC 50 W was applied to a Co target having a diameter of 5 cm in an argon gas 0.1 Pa atmosphere. Film formation was performed in such a film formation time that the film thickness of Co formed on the protrusions was 10 nm. Thereafter, when the cross section of the sample was observed with an FE-SEM, it was observed that the magnetic material 28 was formed on the protrusions 25 regularly arranged on the underlayer 21 as shown in FIG. In addition, the magnetic body 29 formed on the underlayer 21 was thinner than the magnetic body 28 formed on the protrusions 25 and was about 5 nm.

  As described above, it was confirmed that the magnetic material was disposed on the regularly arranged protrusions obtained by anodic oxidation. Since the regularly arranged protrusions produced in this example are formed from the oxide of the underlayer, they have excellent resistance to film formation and heat treatment. Furthermore, since the concavo-convex structure having regularly arranged protrusions is produced by combining nanoimprint using resin and anodization, even a high-density pattern can be easily produced.

(Example 2)
The present embodiment relates to obtaining a concavo-convex structure having protrusions regularly arranged by anodic oxidation, and disposing a magnetic body on top of the protrusion. In particular, unlike Example 1, this includes controlling the crystal orientation of the magnetic material by disposing an intermediate layer between the upper portion of the protrusion and the magnetic material.

  First, as in Example 1, an uneven structure was prepared using anodization. Next, MgO functioning as an intermediate layer of the magnetic material was formed by sputtering. The distance between the target and the sample was 15 cm, and sputtering was performed by applying power of RF 50 W in an argon gas 0.1 Pa atmosphere to an MgO target having a diameter of 5 cm. Film formation was performed so that the film thickness of MgO on the upper surface of the protrusion was 5 nm. When the cross section of the sample after film formation was observed by FE-SEM, as shown in FIG. 7, MgO 31 was formed mainly on the upper surface of the protrusion 25 and the bottom of the recess, and almost all MgO was formed on the side wall of the protrusion. It was not in a state. Further, from the X-ray diffraction result of the sample, it was confirmed that the MgO was oriented with the surface composed of the (001) crystal plane.

  Next, a magnetic material was formed by sputtering in the same manner as in Example 1. In this example, FePt was used as a target, and the film was formed so that the composition ratio of Fe in the film was 50 atomic% and the film thickness was 10 nm. When the cross section of the sample after film formation was observed with FE-SEM, it was observed that FePt 32 was formed on MgO 31 as the intermediate layer 30 in the shape shown in FIG.

  Further, the sample after film formation was annealed at 500 ° C. in a vacuum. In the annealed sample, FePt was in a state in which the c-axis of the L10 structure was oriented in the direction perpendicular to the substrate due to the influence of the MgO (001) surface that is the underlayer of the magnetic material. In addition, magnetic anisotropy in the direction perpendicular to the substrate was confirmed from the magnetization curve of the sample.

  As described above, by arranging the intermediate layer between the upper portion of the protrusion and the magnetic body, the crystal orientation of the magnetic body can be controlled. As in this embodiment, by arranging magnetic bodies having magnetic anisotropy in the vertical direction on the top of the regularly arranged projections, the magnetic body arranged on the top of the projections is used as a recording portion. A recordable patterned medium can be manufactured.

(Example 3)
The present embodiment relates to obtaining a concavo-convex structure having protrusions regularly arranged by anodic oxidation, and disposing a magnetic body on top of the protrusion. In particular, in Example 1, it relates to a case where the oxide of the underlayer is grown to the inside of the pores of the porous film.

  First, as in Example 1, anodization was performed to form a porous film having a triangular lattice arrangement. However, unlike Example 1, in this example, Nb was used as the material for the underlayer. Next, the porous film thus obtained was immersed in a 5 wt% phosphoric acid aqueous solution having a bath temperature of 22 ° C. for 20 minutes to perform a pore size expansion process by wet etching. When the plane of the sample was observed with FE-SEM, the hole diameter before the hole diameter expansion treatment was 20 nm, but was expanded to 35 nm.

  Next, the sample was anodized at an applied voltage of 40 V in a 0.15 mol / L ammonium borate aqueous solution having a bath temperature of 22 ° C. As a result, the growth of the oxide of the underlayer proceeds and the volume expands, so that the hole 24 is filled with the Nb oxide 33 which is the oxide of the underlayer 21 as shown in FIG. It was. At this time, the height of the Nb oxide grown by anodic oxidation with an aqueous ammonium borate solution was 50 nm.

  Furthermore, by polishing the surface of the sample with diamond slurry, the porous film and the oxide of Nb were simultaneously polished to obtain the state shown in FIG. In this state, the porous film was removed in the same manner as in Example 1 to obtain an uneven structure having protrusions 34 as shown in FIG. Unlike Example 1, the upper surface of the obtained protrusion 34 has a smooth surface because it is surface-polished. Moreover, although the diameter of the upper surface of the protrusion 34 was 35 nm larger than Example 1, it can be adjusted with the time of a hole diameter expansion process. Furthermore, although the height of the projection 34 was 40 nm, it can be adjusted by the surface polishing time.

Next, when the magnetic material was deposited on the resulting concavo-convex structure in the same manner as in Example 1, it was found that the magnetic material was arranged on the top of the regularly arranged projections as in Example 1. It could be confirmed.
By growing the oxide of the underlayer by anodic oxidation in the pores of the porous film as in this embodiment, it is possible to change the size of the protrusions such as the diameter and height. In addition, it is possible to flatten the upper surface of the protrusion on which the magnetic material serving as the recording layer is disposed.

(Example 4)
The present embodiment relates to obtaining a concavo-convex structure having protrusions regularly arranged by anodic oxidation, and disposing a magnetic body on top of the protrusion. In particular, in Example 1, it relates to a case where the oxide of the underlayer is grown to the inside of the pores of the porous film.

  First, anodization was performed to form a porous film having a square lattice arrangement. However, unlike Example 1, 30 nm of Nb was deposited on 5 nm of Ti, and further AlHf containing 7 atomic% of Hf was sputtered on it to 60 nm. In addition, a square array consisting of small depressions at 25 nm intervals was formed on the AlHf surface by using the FIB method as a starting point for anodization. Furthermore, anodization was performed at an applied voltage of 10 V in a 1.0 mol / L sulfuric acid aqueous solution having a bath temperature of 3 ° C., and then the resulting porous film was immersed in a 5 wt% phosphoric acid aqueous solution having a bath temperature of 20 ° C. The hole diameter enlargement process by wet etching was performed. When the plane of the sample was observed with FE-SEM, the pore diameter was 12 nm.

  Next, the sample was anodized in an aqueous 0.15 mol / L ammonium borate solution having a bath temperature of 22 ° C. at an applied voltage of 25V. As a result, the growth of the oxide of the underlayer proceeds and the volume expands, so that the hole 24 is filled with the Nb oxide 33 which is the oxide of the underlayer 21 as shown in FIG. It was.

Next, heat treatment was performed at 350 ° C. in an air atmosphere.
Further, by polishing the surface of the sample, the porous film and the oxide of Nb were simultaneously polished. Subsequently, the concavo-convex structure A having a protrusion having a diameter of 12 nm and a height of 25 nm was obtained by removing the porous film in a 5 wt% phosphoric acid aqueous solution at 25 ° C. in the same manner as in Example 1.

On the other hand, a concavo-convex structure B not subjected to the heat treatment process was prepared as a comparative sample. The uneven structure B also has a diameter of 12 nm and a height of 25 nm.
Here, in order to compare the strength of the concavo-convex structures A and B, the intensity comparison was performed by ultrasonic treatment under the same conditions. It was found that the uneven structure A was a stable structure. A stable concavo-convex structure was obtained even for protrusions having a small diameter and a large aspect ratio between the diameter and the height.

  Further, when the magnetic material was deposited on the concavo-convex structure A in the same manner as in Example 1, it was confirmed that the magnetic material was disposed on the top of the regularly arranged projections in the same manner as in Example 1. It was.

(Example 5: NbO convex production by anodic oxidation)
The present embodiment relates to a manufacturing method for obtaining a convex structure having a hole diameter enlarged toward the outside of a member by oxidizing a base layer formed on the member by an anodic oxidation method. This will be described with reference to FIGS.

  A base layer 101 made of niobium (Nb) having a thickness of 30 nm is formed on a silicon substrate 103. Further, an anodized layer 102 made of an aluminum-hafnium alloy (AlHf, Hf = 5 to 6 atomic%) having a thickness of 80 nm is formed to form a member 105 (FIG. 12A).

  Next, this member is immersed in a sulfuric acid aqueous solution (1 mol / L, 20 ° C.) as an anode, and an electrode is applied to form a hole 106 in the AlHf alloy layer (FIG. 12B). At this time, Nb close to the bottom of the hole is oxidized to become Nb oxide and protrudes into the hole. Here, in the formation of holes by anodic oxidation, since the arrangement of the holes is generally random, it is necessary to combine with a technique such as JP-A-2004-66447 when regularly arranging the holes.

  Next, a step of immersing the member in an aqueous solution of ammonium borate (0.15 mol / L, 20 ° C.) and applying a voltage as an anode and a pore-wide step of expanding the pore diameter of the portion where the Nb oxide convex structure is not formed Repeat. Thereby, the Nb oxide convex structure whose diameter increased toward the outside of the member is formed. Here, the height of the Nb oxide is proportional to the applied voltage. First, a voltage of 11 V was applied to grow Nb oxide (FIG. 12C), the voltage application was stopped, and the member was immersed in an aqueous phosphoric acid solution (5 wt%, 20 ° C.) for 10 minutes to obtain a pore size. Is enlarged (FIG. 12D). Since it is difficult for the liquid to enter the portion where the Nb oxide is formed, the pore diameter is also difficult to expand. Next, the member is returned to the ammonium borate aqueous solution, a voltage of 19 V is applied (FIG. 12E), and then returned to the phosphoric acid aqueous solution and immersed for 10 minutes (FIG. 12F). Further, the member is returned to the ammonium borate aqueous solution, and a voltage of 27 V is applied (FIG. 12 (g)). As a result, an Nb oxide having a shape with a height of 50 nm and gradually increasing as the pore diameter moves away from the member can be obtained. The shape of the hole diameter expansion is not a clear stepped shape.

  Next, the strength of the Nb oxide is increased by baking at 300 ° C. for 10 minutes. At this time, since the shape of the upper surface of the Nb oxide is slightly rounded, polishing is performed with colloidal silica until the upper surface of the Nb oxide is exposed and flattened. When the member is immersed in an aqueous phosphoric acid solution for 5 hours, the AlHf alloy film is dissolved and only the Nb oxide convex structure remains (FIG. 13A). By sputtering, ruthenium (Ru) 5 nm and cobalt-platinum alloy (CoPt) are laminated in this order to form a magnetic recording layer. If the sputtering is performed from the direction perpendicular to the substrate, the magnetic recording layer is easy to be stacked in the recess between the upper surface of the Nb oxide and the Nb oxide and difficult to stack on the Nb oxide side wall. Separation of the magnetic recording layer between the convex structures can be realized (FIG. 13B).

  In order to use such a structure as a magnetic recording medium, the following post-process is required. First, SOG (Spin-On-Glass) is applied by spin coating and baked to fill the voids of the Nb oxide convex structure (FIG. 13C). A dry etching method is performed with a fluorine-based gas, and only the SOG is removed from the upper portion to expose the magnetic recording layer 117 (FIG. 13D). As a protective layer, 3 nm of diamond-like carbon (DLC) and 5 nm of a lubricant are stacked (FIG. 13E).

(Example 6: Metal plating)
In Example 5, it shows about the case where the material which comprises a convex structure is a metal.
In the member configuration of Example 5, the base layer 101 is copper (Cu). When anodic oxidation is performed under the same conditions, the Cu layer is exposed when the hole 106 reaches the base layer. A member is immersed in the platinum electroplating bath using the exposed portion as an electrode, and electroplating is performed using a cathode. Since the growth height of the convex structure is determined by the plating time, the plating for a certain time and the hole diameter enlargement process are repeated. Since the plating bath is generally acidic, it is preferable to select a plating bath that does not erode the anodized layer. Further, it is preferable that the material of the convex structure to be produced is not corroded by the phosphoric acid aqueous solution when the anodized layer is removed.

(Example 7: When using a phase separation membrane)
The present embodiment relates to a method of manufacturing a magnetic recording medium when a phase separation film is used.
On the Si substrate, Nb serving as an underlayer is formed to a thickness of 50 nm with an Al composition of 40 atomic% and 60 atomic%, respectively, and an Al—Si phase separation film and an Al—Ge phase separation film.

  Next, the Al—Si phase separation membrane was immersed in concentrated sulfuric acid, and the Al—Ge phase separation membrane was immersed in phosphoric acid, respectively, to dissolve only the Al cylinder portion. Thereafter, it can be confirmed that the phase separation film is a porous film having Al portions as pores and pores perpendicular to the substrate.

  Further, it is immersed in an aqueous solution of ammonium borate at 22 ° C. and 0.15 mol / L, the applied voltage is increased stepwise, and finally anodized with an applied voltage of 20V. As a result, it was confirmed that the oxide of the underlayer Nb was grown at a height of about 25 nm in the pores of the porous film regardless of whether it was made of an Al—Si or Al—Ge phase separation film. it can.

  Therefore, it can be confirmed that niobium oxide protrusions can be obtained by selectively removing the porous membrane portion obtained from the Al—Si and Al—Ge phase separation membrane with an aqueous sodium hydroxide solution. In addition, when an Al—Ge phase separation film is used as a starting material, it can be confirmed that even an aqueous hydrogen peroxide solution can be effectively dissolved.

  Since the pore diameter of these films is 5 nm for the Al-Si phase separation film and 10 nm for the Al-Ge phase separation film, a magnetic recording medium capable of high-density recording can be formed by forming the magnetic layer of another embodiment. Can be made.

(Example 8: Constriction)
The present embodiment relates to a manufacturing method in which an intermediate layer formed on a member is oxidized by an anodic oxidation method to obtain a convex structure having a shape constricted toward the outside of the member. This will be described with reference to FIG.

  On the silicon substrate 103, titanium (Ti) 10 nm and Al oxide 10 nm are stacked as an oxide layer 110, Nb 30 nm is stacked as an intermediate layer 109, and Al oxide 15 nm is stacked as an oxide layer, which is used as a member (FIG. 14A). ). A hole structure regularly arranged in a triangular lattice shape with a period of 50 nm is formed in the Nb layer and the Al oxide layer by a photolithography method (FIG. 14B), immersed in ammonium borate as an anode, and voltage Apply 10 nm. The Al oxide layer passes a slight current, and the Nb layer is oxidized to expand its volume and protrude to the side surface of the hole (FIG. 14C). When the hole is filled with a filler and immersed in a phosphoric acid aqueous solution to dissolve and remove the Al oxide layer, a constricted convex structure of the filler remains (FIG. 14D).

Example 9
(Make reverse taper type hole by imprinting, NO is easy. Remove polymer after laminating magnetic material OR Laminating magnetic material after polymer removal)
In this example, a concave structure whose width increases toward the outside of the member by the imprint method is formed, the base layer formed on the member is oxidized by the anodic oxidation method, and the width increases toward the outside of the member. The present invention relates to a manufacturing method for obtaining a convex structure. This will be described with reference to FIGS. 15 and 16.

  A base layer 101 made of Nb having a thickness of 30 nm is formed on a silicon substrate 103, and a transfer layer 116 made of a polymethyl methacrylate (PMMA) layer having a thickness of 100 nm is further formed as a member 105 (FIG. 15A). ). Further, a mold 111 (FIG. 16: perspective view of the mold) made of Si having convex portions in which trapezoidal line structures are arranged in a rectangular lattice shape is produced.

  The member is heated to room temperature and the mold is heated to 130 ° C., the mold is pressed against the PMMA layer and held for 1 minute, and then the mold is cooled and then peeled to form the concave structure 113 (FIG. 15B). The shape of the formed concave structure is almost equal to the shape of the mold protrusion 112. The residual film of the PMMA layer is removed by a dry etching method using oxygen plasma, and the Nb layer is exposed in the concave structure 113 (FIG. 15C).

  Next, the member 105 is immersed in ammonium borate as an anode, and a voltage is applied to form the oxide 104 of the underlayer made of Nb oxide (FIG. 15D). Then, after polishing and flattening the upper surface of the Nb layer, it is immersed in acetone to dissolve and remove the PMMA layer, whereby a convex structure having a line shape and increasing in width toward the outside of the member is obtained. The imprinted PMMA has slight transfer spots, but the oxide is formed at a height proportional to the voltage and further polished, so that the resulting convex structure does not have height spots. There is.

  When used as a magnetic recording medium, the PMMA layer is removed and then CoPt is stacked to form a magnetic recording layer. Alternatively, PMMA may be dissolved after CoPt is laminated after polishing, and only CoPt on PMMA may be removed by a lift-off method.

(Example 10: A magnetic layer is formed by forming a reverse taper projection by imprint itself)
The present embodiment relates to a manufacturing method for obtaining a convex structure whose width increases toward the outside of a member by an imprint method. This will be described with reference to FIGS.

  A transfer layer 116 made of a silsesquioxane (HSQ) layer having a thickness of 100 nm is formed on the silicon substrate 103 to form a member 105 (FIG. 17A). Further, a mold 111 (FIG. 18: perspective view of the mold) made of polydimethylsiloxane (PDMS) having recesses in which trapezoidal line structures are arranged in a rectangular lattice shape is produced.

  The member is pre-baked at 60 ° C., a release agent is applied to the mold, pressed against the HSQ layer at room temperature, held for 1 minute, and then fired at 150 ° C. for 1 minute to completely vaporize and cure the HSQ solvent. Peel from. Further, when exposed to an ozone atmosphere while firing at 200 ° C., the oxidation further proceeds and a silicon oxide convex structure 115 is formed (FIG. 17B). Since the imprint mold by PDMS has elasticity, the opening portion of the mold recess 114 is deformed when the mold is peeled off, and the upper portion of the convex structure 115 wider than the mold opening can also be peeled off. Thereby, the convex structure whose width becomes large toward the outside of the member can be formed.

  In the method of manufacturing a magnetic recording medium of the present invention, the shape and height of the projections that form the magnetic material to be the recording portion can be uniformly formed over a large area, so the field of information storage by high-density magnetic recording Can be used.

It is a schematic diagram which shows the cross section of the porous membrane | film | coat obtained by anodic oxidation. It is a schematic diagram which shows the cross section of the porous membrane | film | coat obtained by anodic oxidation. It is a schematic diagram which shows the state in which the oxide of the base layer grew on the barrier layer of the porous film. It is a schematic diagram which shows the state which the oxide of the foundation | substrate layer grew to the inside of the hole of a porous membrane | film | coat. It is a schematic diagram which shows the regularly arranged protrusion which consists of an oxide of a base layer. It is a schematic diagram which shows an example of the magnetic recording medium by this invention. It is a schematic diagram which shows the base layer formed into a film on the upper surface of a protrusion, and the bottom part of a recessed part. It is a schematic diagram which shows the base layer and magnetic body which were formed into a film on the upper surface of a protrusion, and the bottom part of a recessed part. It is a schematic diagram which shows the state which the oxide of the foundation | substrate layer grew to the inside of the hole of a porous membrane | film | coat. It is a schematic diagram which shows the cross section of the sample after surface polishing. It is a schematic diagram which shows the regularly arranged protrusion which consists of an oxide of a base layer. It is process drawing which shows the manufacturing method which obtains the convex structure which the hole diameter expanded toward the outer side of the member by the anodic oxidation of Example 5 of this invention. It is process drawing which shows the manufacturing method which obtains the convex structure which the hole diameter expanded toward the outer side of the member by the anodic oxidation of Example 5 of this invention. It is process drawing which shows the manufacturing method which oxidizes the intermediate | middle layer formed in the member by the anodic oxidation method of Example 7 of this invention, and obtains the convex structure of the shape narrowed toward the outer side of the member. It is process drawing which shows the manufacturing method which oxidizes the base layer formed on the member by the anodic oxidation method of Example 8 of this invention, and obtains the convex structure widened toward the outer side of the member. It is a perspective view of the mold used for Example 8 of this invention. It is process drawing which shows the manufacturing method manufacturing method which obtains the convex structure which width expands toward the outer side of a member by the imprint method of Example 9 of this invention. It is a perspective view of the mold used for Example 9 of this invention. It is a schematic diagram which shows the process for obtaining a porous membrane from the phase-separation membrane by this invention. It is a schematic diagram which shows an example of the patterned media by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Hole 11 Substrate 12 Porous film 13 Oxidized layer oxide 14 Barrier layer 20 Barrier layer 21 Underlayer 22 Porous film 23 Underlayer oxide 24 Hole 25 Projection 26 Substrate 27 Porous film bottom 28 Magnetic Body 29 magnetic body 30 intermediate layer 31 MgO
32 FePt
33 Nb oxide 34 Protrusion 101 Underlayer 102 Anodized layer 103 Substrate 104 Underlayer oxide 105 Member 106 Hole 107 Protective layer 109 Intermediate layer 110 Oxide layer 111 Mold 112 Mold convex 113 Concave structure 114 Mold concave 115 Convex structure 116 Transfer layer 117 Magnetic recording layer 118 Sealing material 9900 Underlayer 9910 Phase separation film 9912 Al cylinder portion 9913 Silicon region surrounding aluminum cylinder 9950 Porous film 9951 Hole 9960 Oxide 2990 Substrate 2991 Convex-shaped member 2992 Magnetic film 2993 Upper surface portion of convex shaped member 2994 Between convex shaped portions 2995 Angle of reverse tapered portion

Claims (15)

A patterned medium comprising a magnetic recording layer,
On the substrate , a plurality of convex members are provided in the form of dots via an underlayer containing at least one element selected from Ti, Zr, Hf, Nb, Ta, Mo, W ,
The convex member includes an oxide of the element cross-sectional area of a plane parallel to the substrate is included in have a smaller shape toward the substrate, and the underlying layer,
Further, the magnetic recording layer is provided on the upper surface portion of the convex member so as not to contact between the adjacent upper surface portions. The patterned medium according to claim 1, wherein the convex member has a height of 5 nm to 29 nm, and a soft magnetic layer is provided between the substrate and the convex member . As the difference in height between the upper surface portion of the adjacent said convex member is less than 5 nm, according to claim 1 or 2, characterized in that the height between the convex member adjacent are aligned Patterned media. The On the upper surface of the convex member, with the alignment film, a patterned medium according to any one of claims 1 to 3, characterized in that said magnetic recording layer is provided. The convex on the side surface of the shaped member, patterned medium according to claim 1, any one of 4, wherein said magnetic recording layer is not provided. Wherein the substrate, patterned medium according to claim 1, any one of 5, characterized in that the material constituting the magnetic recording layer is provided between the plurality of the convex member. A step of preparing a member having a base layer and an anodized layer in this order from the substrate side on the substrate; forming holes in the member by anodization; and adding the oxide of the base layer to the holes The step of growing the outer side of the member, the step of expanding the hole diameter of the hole, the member subjected to the enlargement process of the hole diameter is further anodized, and the oxide of the underlayer is formed in the hole. , possess a step of further growth toward the outside of the member, the shape of the oxide of the underlying layer to be grown into said holes, the cross-sectional area in the direction parallel to the substrate plane of the oxide, the A method of manufacturing a substrate, characterized in that the substrate is reduced toward the substrate. 8. The method for manufacturing a substrate according to claim 7 , wherein the generation of the oxide of the underlayer by the anodizing treatment and the treatment for expanding the pore diameter are repeated. 9. The method of manufacturing a substrate according to claim 7, wherein a magnetic film is provided on the oxide. Removing an anodized layer that has been anodized and that exists between the oxides of the plurality of underlying layers formed on the substrate after or before providing a magnetic film on the oxide; The method for manufacturing a substrate according to any one of claims 7 to 9 , wherein   A step of disposing a layer made of a material whose volume is expanded by oxidation treatment, a step of providing a plurality of convex members having a tapered shape in a direction away from the substrate on the layer, and oxidizing the layer Thus, there is provided a method for producing a substrate, comprising a step of growing an oxide of the material between the convex members. The method for manufacturing a base according to claim 11 , wherein the convex member on the substrate is formed by an imprint method. The method of manufacturing a substrate according to claim 11 , wherein a magnetic film is laminated on the oxide after growing the oxide of the material. 14. The method for manufacturing a substrate according to claim 13 , wherein the convex member is removed after the magnetic films are laminated. The method for manufacturing a substrate according to claim 13 , wherein the magnetic film is formed on the oxide after removing the convex member.

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