JP2006068827A - Nanohole array, manufacturing method thereof, composite material and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for manufacturing a nanohole array, the pore period, pore diameter and film thickness of which are controlled with high accuracy. <P>SOLUTION: According to this manufacturing method of a nanohole array, a pore of an anodized porous alumina film is filled with a first material, and further the periphery of the porous alumina film is also covered with the first material. After that, the alumina is removed to manufacture a pillar array structure having upper and lower support layers. A void between pillars of the pillar array structure having the upper and lower support layers is filled with a second material. After that, the pillar array structure is removed to manufacture a nanohole array. This invention further provides a composite material and a manufacturing method thereof using the above nanohole array. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a nanohole array and a manufacturing method thereof, a composite material using the nanohole array, and a manufacturing method thereof.

  Porous materials having fine pores of submicron to nanometer scale are expected to be applied to catalysts, sensors, electronic / optical devices, and the like. Fabrication of porous structural materials has been studied with various substances such as metals, metal oxides, and polymers, and the fabrication methods are diverse. In general, the formed porous structure material has a branched mesh-like pore structure or a structure in which cylindrical pores are irregularly arranged, and pores having a uniform size with respect to the membrane surface. It is difficult to fabricate a vertically aligned hole array structure. In order to solve these problems, the characteristic geometric structure of anodized porous alumina is transferred to other materials by a two-step transfer process, and pores are regularly arranged on a nanometer scale. A technique for obtaining a hole array structure has been proposed (Non-Patent Document 1). In this method, the pores of anodized porous alumina are filled with a material such as a polymer or metal, and then the alumina is dissolved and removed to produce a negative structure, and the material is formed again using the formed negative mold as a template. In this way, a nanohole array in which nanometer-scale pores are regularly arranged can be obtained.

However, in the above method, if the length of the negative pillar structure is increased, it is difficult to maintain an upright structure after dissolving and removing alumina, and it is difficult to maintain a regular structure. It was. For this reason, it is difficult to produce a high aspect ratio nanohole array having a regular pore arrangement in the prior art, and a highly ordered nanohole array having an aspect ratio of 10 or more, which is the ratio of pore diameter to pore depth. I haven't come to get. Further, the conventional method has a problem that it is difficult to strictly control the film thickness of the hole array obtained.
H. Masuda, and K. Fukuda, Science, 268, 1466 (1995)

  In order to solve the above-mentioned problems in producing a nanohole array that is expected to be applied in a wide range of applications, the present invention facilitates a high-aspect-ratio hole array in which pores of uniform size are regularly arranged. This has been made as a result of a keen examination of the means to obtain. That is, the subject of this invention is providing the technique which can produce the nanohole array which controlled the pore period, the pore diameter, and the film thickness with high precision with a large area. In addition, another object of the present invention is to provide a composite material using such a nanohole array and a method for producing the same.

  In order to solve the above-mentioned problems, the present invention provides a hole array excellent in pore arrangement regularity using a pillar array structure produced using an anodized porous alumina film as a template.

  That is, in the method for producing a nanohole array according to the present invention, the pores of the anodized porous alumina film are filled with the first substance, and the porous alumina film is covered with the first substance, and then the alumina is removed. From the method characterized in that a hole array is manufactured by filling a space between pillars of a pillar array structure having an upper and lower support layer manufactured by filling a second substance and then removing the pillar array structure. Become.

  The nanohole array according to the present invention is prepared by filling and covering the pores of the anodized porous alumina film and the periphery of the alumina base material with the first substance such as metal, metal oxide, polymer, etc. Only a pillar array structure formed by selective dissolution and removal is used as a template. Since the pillar array structure formed by such a method is a structure in which each pillar is supported by two layers, an upper layer and a lower layer, the pillar upright structure can be maintained even after the alumina portion is dissolved and removed. Is possible. Therefore, it is suitable as a template for producing a hole array in which fine holes perpendicular to the film surface are regularly arranged. By filling the voids of the formed pillar array structure with the second substance, and then removing the pillar structure part composed of the first substance, a nanohole array structure having excellent pore arrangement regularity is obtained. Can be made.

  In the above method, the pore diameter and pore depth of the anodized porous alumina film can be controlled by changing the anodizing voltage and the anodizing time. Can be controlled in the range of 10 nm to 450 nm and the pore depth in the range of 100 nm to 100 μm. Therefore, the second substance can be filled in the voids between the pillars of the pillar array structure manufactured using the anodized porous alumina film having a pore diameter of 10 nm to 450 nm. Further, the second substance can be filled in the gaps between the pillars of the pillar array structure manufactured using the anodized porous alumina film having a thickness of 100 nm to 100 μm.

  The nanohole array according to the present invention was prepared by filling the pores of the anodized porous alumina film with the first substance, covering the porous alumina film with the first substance, and then removing the alumina. The pillar array structure having the upper and lower support layers is filled with the second substance in the gap between the pillars, and then the pillar array structure is removed.

  This nanohole array can also be produced using a pillar array structure produced using an anodized porous alumina film having a pore diameter of 10 nm to 450 nm, and an anodized porous film having a film thickness of 100 nm to 100 μm. It can be produced using a pillar array structure produced using an alumina film.

  The above-described method for filling the voids in the pillar array structure with a substance is also effective as a method for producing a structure in which different substances are combined on a submicron to nanometer scale. By removing the upper layer and the lower layer of the pillar array structure after the material is filled, a hole array structure in which other materials are filled in the pores can also be obtained.

  As the second substance that fills the gaps between the pillars of the pillar array structure, for example, any of metal, metal salt, inorganic oxide, monomer, and polymer can be used. Further, in particular, a fluorine-based resin (for example, “Teflon” (registered trademark)) can be used as the second substance that fills the gaps between the pillars of the pillar array structure.

  In the method for producing a composite material according to the present invention, the first substance is filled in the pores of the anodized porous alumina film, and the alumina is removed after covering the porous alumina film with the first substance. Fill the voids between the pillars of the pillar array structure having the upper and lower support layers prepared by the above, and then remove the upper and lower support layers into the pores of the hole array made of the second substance. The method comprises producing a composite material filled with a first substance.

  Also in this method, the second substance can be filled in the voids between the pillars of the pillar array structure manufactured using the anodized porous alumina film having a pore diameter of 10 nm to 450 nm, and the film thickness is 100 nm. The space between the pillars of the pillar array structure manufactured using the anodized porous alumina film having a thickness of 100 μm to 100 μm can be filled with the second substance.

  The composite material according to the present invention was manufactured by filling the pores of the anodized porous alumina film with the first substance, and covering the porous alumina film with the first substance and then removing the alumina. After filling the space between the pillars of the pillar array structure having the upper and lower support layers with the second substance, the first substance is placed in the pores of the hole array made of the second substance by removing the upper and lower support layers. It consists of what was comprised by the structure filled up.

  This composite material can also be produced using a pillar array structure produced using an anodized porous alumina film having a pore diameter of 10 nm to 450 nm, and an anodized porous film having a film thickness of 100 nm to 100 μm. It can be produced using a pillar array structure produced using an alumina film.

  Also in this composite material, for example, any of a metal, a metal salt, an inorganic oxide, a monomer, and a polymer can be used as the second substance that fills the gaps between the pillars of the pillar array structure. Further, in particular, a fluorine-based resin (for example, “Teflon” (registered trademark)) can be used as the second substance that fills the gaps between the pillars of the pillar array structure.

  According to the nanohole array and the method for manufacturing the same according to the present invention, a high regularity is produced without tilting each pillar by the upper and lower support layers, which is produced using an anodized porous alumina film having pores arranged with high regularity. Since the hole array was fabricated using the pillar array structure held in a state in which the predetermined shape of the hole was maintained as a template, the nanohole array in which the pore period, the pore diameter, and the film thickness were controlled with a high degree of accuracy was used. Can be produced.

  Further, according to the composite material and the manufacturing method thereof according to the present invention, the upper and lower support layers are removed in the process of manufacturing the nanohole array as described above, and the first substance is placed in the pores of the nanohole array made of the second substance. Since the composite material in the form filled with can be configured, the composite material in which the first substance in the pillar form is uniformly arranged with a desired cycle and diameter and high regularity in the second substance can be obtained. It is possible to form a composite structure material having a desired form even in a material that has been difficult to be uniformly compounded in the past.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
After anodizing aluminum in an acidic electrolyte to produce porous alumina, the base metal and the bottom of the oxide film are removed, thereby forming a porous alumina 1 film having pores 1a as shown in FIG. 1 (A). Obtainable. In order to produce a pillar array structure as a template material for producing the hole array, the first substance 2 is filled into the pores of the porous alumina film 1 having the through holes, and the periphery of the alumina base material is also formed. After coating with the first substance 2, only the alumina portion is selectively dissolved and removed. As a result, a pillar structure 3 is formed which is formed of the first substance 2 and includes the pillars formed with the same pore period between the upper and lower support layers (FIG. 1B). As the first substance to be filled, a polymer, a metal, a metal oxide, or the like can be used. For example, after immersing a porous alumina film formed into a through-hole in a monomer solution and polymerizing with heat or light, a structure in which the inside and the periphery of the pores of the porous alumina film are filled with a polymer material can be obtained.

  Next, the alumina embedded in the first substance is removed (FIG. 1C). In order to selectively dissolve and remove the alumina embedded in the first material, it is necessary to polish the filling material and expose a part of the side surface of the porous alumina. As a polishing method for the filling material, in addition to mechanical polishing, polishing in vacuum such as ion milling can be used. The porous alumina embedded in the filling material can be selectively removed by immersing it in an acid or alkali solution in which the filling material does not dissolve, with a part of the porous alumina being exposed. The pillar array structure 3 having the upper and lower support layers made of the first substance 2 can be produced.

  The voids of the pillar array structure 3 formed by removing the alumina portion are filled with a second substance 4 such as a polymer, a metal, or a metal oxide (FIG. 1D), and the pillar structure 3 portion is selectively selected. The hole array 5 that faithfully reproduces the structure of the porous alumina described above can be obtained by dissolving in (1E). For filling the voids of the pillar array structure 3 with the second substance, a filling method such as an electrodeposition method, a sol-gel method, or a CVD method can be used. Further, the dissolution of the pillar array structure can be selectively removed by using an acid, an alkali, or an organic solvent in which the second substance filled in the gaps between the pillars is not dissolved.

  According to the present invention, it is possible to form a composite material in which different substances are uniformly distributed from a submicron to a nanometer scale by filling the space between the pillars of the pillar array structure with the second substance. . By using this method, it is possible to produce a composite structure material even for a material that is inherently difficult to be uniformly composited. In addition, by removing the upper and lower layers of the pillar array structure after filling the substance, only the pillar portion of the pillar structure made of the first substance is left inside the pores of the hole array structure made of the second substance. It is also possible to obtain a composite structure. For removal of the upper and lower layers of the pillar array structure, mechanical polishing, polishing in vacuum such as ion milling, wet etching, or the like can be used.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by this Example.
Example 1 [Preparation of Ni Hall Array]
A SiC mold having a structure in which protrusions were regularly arranged with a period of 500 nm was pressed against the surface of an aluminum plate having a purity of 99.99% and a size of 1 cm × 5 cm × 0.5 mm to form a fine uneven pattern on the surface. The textured aluminum plate was anodized in a phosphoric acid aqueous solution adjusted to a concentration of 0.1 M at a bath temperature of 0 ° C. under a direct current of 200 V for 15 minutes to produce highly ordered porous alumina. The obtained anodized porous alumina was immersed in an aqueous phosphoric acid solution adjusted to 10 wt% for 60 minutes to enlarge the pore size. Subsequently, the aluminum portion was selectively dissolved by dipping in a saturated mercuric acid aqueous solution. The bottom part of the obtained anodized porous alumina film was removed using an ion milling device to obtain a through-hole membrane. Porous alumina with through-holes was immersed in a methyl methacrylate monomer solution in which 5 wt% benzoyl peroxide was dissolved as a polymerization initiator, and polymerized by holding at 50 ° C. for 12 hours. Embedded in polymer. Side surfaces of the obtained polymethyl methacrylate were mechanically polished to expose both ends of the porous alumina. An Au layer that acts as an electrode during the formation of the hole array was formed on one surface where the porous alumina was exposed. To form the Au layer, Pt-Pd was sputtered to 30 nm on one side of the sample, and then Au was electrolytically deposited to a thickness of 50 μm at a current density of −1 to −50 mAcm ⁻² using an Au electrodeposition bath. It was. An Ni wire was fixed to the formed Au layer using a conductive paste, and the electrode layer surface was completely covered with an epoxy resin. Thereafter, the sample was immersed in a 10 wt% NaOH aqueous solution for 50 hours, and the porous alumina was dissolved from the exposed alumina surface on which the Au electrode layer was not formed. The obtained pillar array structure was washed in distilled water and then subjected to Ni electrodeposition in the gap between the pillars using the Au layer as an electrode. Ni electrodeposition was performed in a Ni electrodeposition bath for 30 hours under a voltage condition of -1 V against a Ni counter electrode. Thereafter, the polymer pillar array structure was dissolved in chloroform to obtain a Ni hole array having a pore period of 500 nm and a pore diameter of 300 nm as shown in FIG. 2 (observed with an electron microscope).

Example 2 [Production of polymethyl methacrylate hole array]
A highly ordered anodized porous alumina with an enlarged pore size was obtained in the same manner as in Example 1. Pt-Pd was deposited to a thickness of 30 nm on the surface of the formed anodized porous alumina, and Ni was electrolytically deposited to a thickness of 50 μm at a current density of −10 to −100 mAcm ⁻² using a Ni electrodeposition bath. The aluminum ingot portion of the sample was removed by dipping in a saturated iodine methanol solution. Each time, the bottom of the alumina film was removed by using an ion milling device to form a through hole. The Ni layer formed in advance was used as an electrode, and Ni was filled into the alumina pores in a Ni electrodeposition bath under a voltage condition of -1 V with respect to the Ni counter electrode. By continuing electrodeposition after filling the pores, a Ni over-deposition layer was formed on the alumina surface, and a structure in which the pores of porous alumina, the bottom, and the top were covered with Ni was produced. The end surface of the porous alumina was exposed by mechanical polishing of the side surface of the obtained sample, and the alumina portion was selectively dissolved and removed by dipping in a 10 wt% NaOH aqueous solution. The obtained Ni nanopillar array structure was washed in distilled water, immersed in a methyl methacrylate monomer, and the monomer solution was filled in the space between the pillars. Polymerization was carried out by maintaining the Ni pillar array structure immersed in the monomer solution for 12 hours at 50 ° C. After the polymerization, the polymethyl methacrylate is mechanically polished to expose the Ni layer, and immersed in a 10 wt% HNO ₃ aqueous solution to selectively dissolve and remove the Ni pillar array structure. As shown in FIG. A polymethylmethacrylate hole array with 500 nm and a pore diameter of 300 nm was obtained (observed with an electron microscope).

Example 3 [Production of “Teflon” Hall Array]
A Ni nanopillar array structure was obtained in the same manner as in Example 2. The voids of the formed Ni nanopillar array structure were filled with a fluorine-based liquid in which a tetrafluoroethylene-perfluorodimethyloxol copolymer was dissolved, and then the solvent was dried at room temperature. The “Teflon” layer formed on the sample surface is mechanically peeled off, the Ni layer is exposed and immersed in a 10 wt% HNO ₃ aqueous solution to selectively dissolve and remove the Ni pillar array structure. Got.

It is a figure which shows the preparation process of the nanohole array which concerns on one embodiment of this invention. FIG. 3 is a view of an Ni hole array produced in Example 1. FIG. 3 is a diagram of a polymethyl methacrylate hole array observed in Example 2.

Explanation of symbols

1 Porous alumina (membrane)
1a pore 2 first material 3 pillar structure 4 second material 5 hole array

Claims (16)

  Pillar array structure having upper and lower support layers prepared by filling the pores of an anodized porous alumina film with a first substance, and further covering the porous alumina film with the first substance and then removing the alumina. A method for producing a nanohole array, comprising: filling a void between the pillars with a second substance, and then removing the pillar array structure to produce a hole array.   The method for producing a nanohole array according to claim 1, wherein the second substance is filled in the voids between the pillars of the pillar array structure produced using an anodized porous alumina film having a pore diameter of 10 nm to 450 nm.   The method for producing a nanohole array according to claim 1 or 2, wherein a second substance is filled in a space between pillars of a pillar array structure produced using an anodized porous alumina film having a thickness of 100 nm to 100 µm.   Pillar array structure having upper and lower support layers prepared by filling the pores of an anodized porous alumina film with a first substance, and further covering the porous alumina film with the first substance and then removing the alumina. After filling the gap between the pillars with a second substance, and then removing the upper and lower support layers, a composite material in which the first substance is filled in the pores of the hole array made of the second substance is obtained. A method for producing a composite material, characterized by comprising:   5. The method for producing a composite material according to claim 4, wherein a second substance is filled in a space between pillars of a pillar array structure produced using an anodized porous alumina film having a pore diameter of 10 nm to 450 nm.   6. The method for producing a composite material according to claim 4 or 5, wherein a second substance is filled in a space between pillars of a pillar array structure manufactured using an anodized porous alumina film having a thickness of 100 nm to 100 μm.   Pillar array structure having upper and lower support layers prepared by filling the pores of an anodized porous alumina film with a first substance, and further covering the porous alumina film with the first substance and then removing the alumina. A nanohole array manufactured by filling the voids between the pillars with a second substance and then removing the pillar array structure.   8. The nanohole array according to claim 7, wherein the nanohole array is manufactured using a pillar array structure manufactured using an anodized porous alumina film having a pore diameter of 10 nm to 450 nm.   9. The nanohole array according to claim 7, wherein the nanohole array is manufactured using a pillar array structure manufactured using an anodized porous alumina film having a thickness of 100 nm to 100 μm.   The nanohole according to any one of claims 7 to 9, wherein any one of a metal, a metal salt, an inorganic oxide, a monomer, and a polymer is used as the second substance that fills a space between pillars of the pillar array structure. Array.   The nanohole array according to any one of claims 7 to 9, wherein a fluorine-based resin is used as the second substance that fills the gaps between the pillars of the pillar array structure.   Pillar array structure having upper and lower support layers prepared by filling the pores of an anodized porous alumina film with a first substance, and further covering the porous alumina film with the first substance and then removing the alumina. After filling the gap between the pillars of the second material with the second substance, the upper and lower support layers are removed to form a structure in which the first substance is filled in the pores of the hole array made of the second substance. A composite material characterized by that.   13. The composite material according to claim 12, wherein the composite material is manufactured using a pillar array structure manufactured using an anodized porous alumina film having a pore diameter of 10 nm to 450 nm.   14. The composite material according to claim 12, wherein the composite material is manufactured using a pillar array structure manufactured using an anodized porous alumina film having a thickness of 100 nm to 100 μm.   The composite according to any one of claims 12 to 14, wherein any one of a metal, a metal salt, an inorganic oxide, a monomer, and a polymer is used as the second substance that fills the gaps between the pillars of the pillar array structure. material.   The composite material according to any one of claims 12 to 14, wherein a fluorine-based resin is used as the second substance that fills the gaps between the pillars of the pillar array structure.

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