JP4395038B2 - Fine structure and manufacturing method thereof - Google Patents

Description

  The present invention relates to a microstructure using an aluminum member having on its surface an anodized film having a plurality of micropores, and a method for producing the same.

  In the technical fields of metal and semiconductor thin films, thin wires, dots, etc., the phenomenon of electrical, optical and chemical peculiarities can be seen by confining the movement of free electrons in a size smaller than a certain characteristic length. It has been known. Such a phenomenon is called “quantum mechanical size effect (quantum size effect)”. Research and development of functional materials applying such a unique phenomenon is being actively conducted. Specifically, a material having a structure finer than several hundred nm is referred to as a “microstructure” or “nanostructure”, and is one of the objects of material development.

  As a method for manufacturing such a fine structure, for example, a method for directly manufacturing a nano structure by a semiconductor processing technique including a fine pattern forming technique such as photolithography, electron beam exposure, and X-ray exposure can be given.

In particular, much research has been conducted on methods for producing nanostructures having a regular microstructure.
For example, as a method for forming a regular structure in a self-regulating manner, an anodized alumina film (anodized film) obtained by subjecting aluminum to an anodizing treatment in an electrolytic solution can be mentioned. It is known that a plurality of fine pores (micropores) having a diameter of about several nm to several hundred nm are regularly formed in the anodized film. By using this self-ordering of the anodized film and obtaining a perfectly regular arrangement, theoretically, hexagonal prism cells with a regular hexagonal bottom centered around the micropores are formed, and adjacent micropores are formed. It is known that the connecting line forms an equilateral triangle.
For example, Non-Patent Document 1 describes an anodized film having micropores. Non-Patent Document 2 describes that pores are spontaneously formed in the anodized film as the oxidation proceeds. Non-Patent Document 3 also proposes forming an Au dot array on a Si substrate using a porous oxide film as a mask.

  The greatest feature of the material of the anodic oxide film is that it adopts a honeycomb structure in which a plurality of micropores are formed in a direction substantially perpendicular to the substrate surface and in parallel at substantially equal intervals. In addition to this, the pore diameter, the pore interval, and the pore depth can be controlled relatively freely, which is a feature not found in other materials (see Non-Patent Document 3).

  As an application example of the anodized film, various devices such as a nano device, a magnetic device, and a light emitter are known. For example, in Patent Document 1, Co and Ni, which are magnetic metals, are filled in a micropore as a magnetic device, ZnO, which is a light emitting material, is filled in a micropore, and an enzyme / antibody is used as a biosensor in a micropore. Application examples such as filling inside are described.

Furthermore, in the field of biosensing, Patent Document 2 describes an example of using a structure in which a metal is filled in the micropores of an anodized film as a sample stage for Raman spectroscopic analysis.
Raman scattering is scattering in which energy is changed by causing an inelastic collision with particles when incident light (photons) hits the particles and scatters. Raman scattered light is used as a technique for spectroscopic analysis, but it is an issue to increase the intensity of scattered light used for measurement in order to improve the sensitivity and accuracy of analysis.
As a phenomenon that enhances the Raman scattered light, a surface-enhanced resonance Raman scattering (SERRS) phenomenon is known. This phenomenon is a phenomenon in which the scattering of certain molecules absorbed on the surface of metal electrodes, sols, crystals, deposited films, semiconductors, etc. is enhanced compared to that in solution, particularly with gold or silver, A remarkable enhancement effect of 10 ¹¹ to 10 ¹⁴ times is observed. Although the generation mechanism of the SERRS phenomenon has not been elucidated at present, it is considered that surface plasmon resonance described later has an influence. Patent Document 2 also aims to use the principle of plasmon resonance as means for enhancing the Raman scattering intensity.

In plasmon resonance, when the surface of a noble metal such as gold or silver is irradiated with light, the metal surface becomes excited, and the plasmon wave, which is a localized electron density wave, interacts with electromagnetic waves (resonance excitation). It is a phenomenon that forms a resonance state. Among them, surface plasmon resonance (SPR) is a surface plasmon wave generated when free electrons on a metal surface become excited when the metal surface is irradiated with light, and the free electrons vibrate in a collective manner. However, a strong electric field is generated.
In the region near the surface where plasmon resonance occurs, specifically, in the region within about 200 nm from the surface, an electric field enhancement of several orders of magnitude (in the example, 10 ⁸ to 10 ¹⁰ times) is observed. A marked uplift in the optical effect is observed. For example, when light is incident on a prism deposited with a thin film of gold or the like at an angle greater than the critical angle, a change in dielectric constant on the surface of the thin film can be detected with high sensitivity as a change in reflected light intensity due to a surface plasmon resonance phenomenon. .
Specifically, when an SPR device using the surface plasmon resonance phenomenon is used, measurement of the reaction amount and binding amount between biomolecules and kinetic analysis can be performed in real time without labeling. The SPR device is applied to the study of interactions between various substances such as immune responses, signal transduction, proteins, and nucleic acids, and recently, a paper on analyzing trace dioxins with the SPR device has been published (Non-patent Document 4). reference.).

Various methods have been studied as a method for increasing plasmon resonance. However, a technique for localizing plasmons by using metal as an isolated particle instead of a thin film is known. For example, Patent Document 2 described above describes a technique in which metal particles are provided on the pores of a regular anodic oxide film and localized.
Here, when using localized plasmon resonance due to metal particles, if the metal particles are in close proximity, the electric field strength is enhanced at the gap between the metal particles, and a state in which plasmon resonance is more likely to occur is realized. (See Non-Patent Document 5). That is, in a device using local plasmon resonance, it is an important requirement that metal particles be present close to each other. For example, it is important that the metal particles be adjacent to each other with an interval of 200 nm or less without contacting them.

JP 2000-31462 A JP 2003-268592 A H. Masuda et. Al. , Jpn. J. et al. Appl. Phys. , Vol. 37 (1998), pp. L1340-1342, Part 2, No. 1 11A, 1 November 1998 (FIG. 2.) “Surface Technology Handbook”, edited by Surface Technology Association (1998), Nikkan Kogyo Shimbun, p. 490-553 Hideki Masuda, “Highly Ordered Metal Nanohole Array Based on Anodized Alumina”, Solid State Physics, 1996, Vol. 31, No. 5, p. 493-499 Kanabe et al., ANALYTICA CHIMICA ACTA 2001, 434: 2: 223-230 Takayuki Okamoto, “Research on metal nanoparticle interactions and biosensors”, [on line], [November 27, 2003 search], Internet <URL: http://www.plasmon.jp/reports/ okamoto.pdf>

As a result of diligent research on a device using localized plasmon resonance, the present inventor has found that a device using a conventional self-ordered anodic oxide film has a problem that the intensity of resonance is not sufficiently high. .
In Non-Patent Document 5, colloidal gold particles are chemically fixed on a glass substrate using 3-aminopropyltrimethoxysilane. The present inventor used this as a plasmon resonance device to perform Raman spectroscopic analysis. It has been found that there is a problem that the reproducibility of signal intensity is poor when it is used for a sample stage.
Therefore, an object of the present invention is to provide a structure that generates localized plasmon resonance having sufficiently high signal intensity and excellent reproducibility.

As a result of diligent research, the present inventor, when using a plasmon resonance device for a sample table for Raman spectroscopic analysis, even if the liquid specimen for analysis is not attached to the surface of the metal particles, It has been found that if the state is not uniform, the signal intensity decreases and the signal reproducibility deteriorates.
Furthermore, the inventor of the present invention uses a device using a self-ordered anodic oxide film to remove a part of the anodic oxide film to obtain a predetermined average surface roughness ( _Ra ), thereby to micropores in the sealing treatment. It has been found that the metal filling unevenness can be eliminated, whereby the signal intensity can be sufficiently increased and the reproducibility can be improved.
The present inventor has completed the present invention based on these findings.

  That is, the present invention provides the following (1) to (5).

(1) A structure manufacturing method for manufacturing a structure having at least a part of an aluminum member having an anodized film having micropores on its surface,
Anodizing the surface of the aluminum member to form an anodized film having micropores;
After the anodizing treatment step, a sealing treatment step of filling the micropores with metal,
After the sealing treatment step, removing a portion of the upper surface of the anodized film, and a surface treatment step of average surface roughness of the surface of the (R _a) to 30nm or less,
After the surface treatment step, on the metal filled by the sealing treatment, by further forming metal particles by electrodeposition, the electrodeposition step to obtain the structure ,
The metal is one of copper, nickel, chromium, zinc, gold, silver, platinum and palladium;
A method for producing a structure, wherein the metal particles are any of copper particles, nickel particles, chromium particles, zinc particles, gold particles, silver particles, platinum particles and palladium particles .

  (2) The structure according to (1), wherein the removal of a part of the upper surface of the anodized film in the surface treatment step removes 20 to 80% of the thickness of the anodized film. Production method.

  (3) The surface treatment step is performed by at least one method selected from the group consisting of mechanical polishing, chemical dissolution, and film removal by an ion beam in a vacuum, as described in (1) or (2) above Manufacturing method of structure.

  (4) The method for manufacturing a structure according to (3), wherein the mechanical polishing is performed by chemical mechanical polishing (CMP).

(5) A structure obtained by the method for producing a structure according to any one of (1) to (4) above,
The average pore diameter of the micropores present in the anodic oxide film is 10 to 500 nm, the variation coefficient of the pore diameter is 5 to 20%, and the average particle diameter of the metal particles is larger than the average pore diameter. A structure that is larger than an average center interval between adjacent micropores (hereinafter also referred to as “pore period”).

When the structure of the present invention is used as a sample stage for Raman spectroscopic analysis, since the metal particles are close and uniform, the localized plasmon resonance is increased, so that the sensitivity is extremely high and the reproduction is achieved. Excellent in properties.
In addition, the structure of the present invention can be suitably used for other devices using plasmon resonance.

The present invention is described in detail below.
The structure manufacturing method of the present invention (hereinafter, also simply referred to as “the manufacturing method of the present invention”) manufactures a structure having at least a part of an aluminum member having an anodized film having micropores on its surface. A method of manufacturing a structure, comprising: (I) an anodizing process for anodizing the surface of an aluminum member to form an anodized film in which micropores are present; and (II) the anodizing process Thereafter, a sealing treatment step of filling the micropores with metal, and (III) after the sealing treatment step, a part of the upper surface of the anodized film is removed, and the average surface roughness (R _a ) a surface treatment step for reducing the thickness to 30 nm or less, and (IV) an electrodeposition step for obtaining the structure by further forming metal particles by electrodeposition on the metal filled by the sealing treatment after the surface treatment step. And having a structure It is a method of manufacture.
Further, the structure of the present invention is a structure obtained by the above production method, wherein the average pore diameter of micropores present in the anodized film is 10 to 500 nm, and the pore diameter variation coefficient is 5 to 5. The structure is 20%, and the average particle diameter of the metal particles is larger than the average pore diameter and smaller than the pore period.
Next, the aluminum member used in the present invention, the above steps (I) to (IV) in the production method of the present invention, and the fine structure obtained will be described in detail.

[Aluminum member]
The aluminum member having an anodized film on the surface used in the present invention can be obtained by subjecting the surface of a member having an aluminum surface to an anodizing treatment.
The member having an aluminum surface is preferably 99.9% by mass or more of high-purity aluminum in which the part to be anodized or the whole member is not limited to a homogeneous material, and can be used as a laminated material or the like. . Specifically, for example, an aluminum substrate such as a substrate in which high-purity aluminum is vapor-deposited on low-purity aluminum (for example, recycled material); sputtering, vapor deposition, CVD, electrodeposition on the surface of silicon wafer, quartz, glass, etc. Examples include a substrate coated with high-purity aluminum by a method such as chemical plating or electroplating; a substrate laminated with an aluminum foil.

  A substrate laminated with an aluminum foil can be obtained by providing an aluminum foil via an adhesive layer using an adhesive on a substrate such as a resin substrate.

  Specific examples of various adhesives include aromatic polyether-based one-component moisture-curable adhesives (for example, SF102RA, manufactured by Dainippon Ink & Chemicals, Inc.); aromatic polyether-based two-component curable adhesives (for example, 2K) -SF-302A / HA550B, manufactured by Dainippon Ink Chemical Co., Ltd.); aliphatic polyester-based two-component curable adhesive (for example, 2K-SF-250A / HA280B, manufactured by Dainippon Ink Chemical Co., Ltd.); for aqueous dry laminate Adhesive (for example, WS305A / LB-60, WS201A / LB-60, WS325A / LJ-55, WS350A / LA-100, WS-320A, all manufactured by Dainippon Ink & Chemicals, Inc.); for organic solvent type dry lamination Adhesives (for example, LX-747A / KX-75, LX-88H (T) / KW-75, LX-732 / KRX-9 , All manufactured by Dainippon Ink Chemical Co., Ltd.); epoxy one-component thermosetting adhesive (for example, EP106, EP138, EP160, EP170, EP171, all manufactured by Cemedine); acrylic oligomer (SGA), etc. 1-component anaerobic curable adhesive (for example, Y-800 series, Y-805GH, both manufactured by Cemedine); special silicone-modified polymer-based one-component elastic adhesive (for example, Super X, manufactured by Cemedine); Phenol resin composite polymer adhesives such as a mixture of phenol resin and butadiene or acrylonitrile rubber, various mixtures of phenol resin and polyvinyl acetate, polyvinyl acetal, polyvinyl butyral or polyvinyl formal, and a mixture of phenol resin and epoxy Two-component condensation reaction type adhesive; Epoxy Two-component addition reaction adhesives such as isocyanate; Two-component radical polymerization adhesives such as acrylic oligomers (SGA); Hot-melt adhesives such as polyimides, polyesters, and polyolefins; Rubbers, polyacrylates, etc. Pressure-sensitive adhesive; 1-pack type room temperature curing adhesive mainly composed of 2-cyanoacrylate; 2-methyl acrylate-based adhesive; 2-cyanoethyl acrylate-based adhesive (for example, Aron Alpha, Tojo, etc.) Synthetic Co., Ltd.) and α-cyanoacrylate adhesives (for example, 3000DX series, manufactured by Cemedine Co.).

  The thickness of the adhesive layer is preferably 3 to 50 μm, more preferably 5 to 20 μm, and still more preferably 10 to 20 μm. The thickness of the adhesive layer can be determined by, for example, a method of observing the fracture surface with a scanning electron microscope (SEM).

  An aluminum foil is provided on the adhesive layer. The thickness of the aluminum foil is preferably 1 to 10 μm, more preferably 1 to 5 μm, and still more preferably 2 to 4 μm.

  As will be described later, in the case of forming a recess that is the starting point of the present anodizing treatment by the self-ordering method, an aluminum substrate is preferable because the member itself having an aluminum surface needs to have a certain thickness.

  Among the aluminum members, the surface on which the anodized film is provided by anodizing treatment preferably has an aluminum purity of 99.5% by mass or more, more preferably 99.80% by mass or more. It is preferably 99% by mass or less, and more preferably 99.95% by mass or less. When the aluminum purity is 99.5% by mass or more, the regularity of the pore arrangement becomes sufficient, and when it is 99.99% by mass or less, it can be manufactured at low cost.

  The surface of the aluminum member is preferably subjected to degreasing and mirror finishing in advance.

<Degreasing treatment>
Degreasing treatment uses acids, alkalis, organic solvents, etc. to dissolve and remove organic components such as dust, fat, and resin that adhere to the aluminum surface, and causes defects in each treatment described later due to the organic components. This is done for the purpose of preventing the occurrence of.
A conventionally known degreasing agent can be used for the degreasing treatment. Specifically, for example, various commercially available degreasing agents can be used by a predetermined method.

Especially, the following each method is illustrated suitably.
A method in which an organic solvent such as various alcohols, various ketones, benzine and volatile oil is brought into contact with the aluminum surface at room temperature (organic solvent method); a solution containing a surfactant such as soap or neutral detergent is used at a temperature ranging from room temperature to 80 ° C A method of contacting the aluminum surface at a temperature and then washing with water (surfactant method); a sulfuric acid aqueous solution having a concentration of 10 to 200 g / L is brought into contact with the aluminum surface at a temperature from room temperature to 70 ° C. for 30 to 80 seconds; Method of washing with water: Electrolysis was carried out by bringing a 5 to 20 g / L sodium hydroxide aqueous solution into contact with the aluminum surface at room temperature for about 30 seconds, with the aluminum surface serving as a cathode and a direct current of 1 to 10 A / dm ^{2 in} current density flowing. Thereafter, a method of neutralizing by bringing a nitric acid aqueous solution having a concentration of 100 to 500 g / L into contact; various known electrolytic solutions for anodizing treatment at room temperature 40 the alkaline aqueous solution in the concentration of 10 to 200 g / L; while in contact with the surface, the aluminum surface by applying a direct current of a current density of 1 to 10 A / dm ² in the cathode, or a method of electrolysis by passing an alternating current A method of bringing the aluminum surface into contact with the aluminum surface at 50 ° C. for 15 to 60 seconds, and then neutralizing it with a nitric acid aqueous solution having a concentration of 100 to 500 g / L; an emulsified liquid obtained by mixing a surfactant, water or the like with light oil or kerosene A method in which the surface of aluminum is brought into contact with the aluminum surface at a temperature from room temperature to 50 ° C. and then washed with water (emulsion degreasing method); a mixed solution of sodium carbonate, phosphates, surfactant, etc. A method of contacting the surface for 30 to 180 seconds and then washing with water (phosphate method).

  The degreasing treatment is preferably a method in which the fat content on the aluminum surface can be removed while aluminum dissolution hardly occurs. In this respect, the organic solvent method, the surfactant method, the emulsion degreasing method, and the phosphate method are preferable.

<Mirror finish processing>
The mirror finish is performed to eliminate unevenness on the surface of the aluminum member and improve the uniformity and reproducibility of the sealing treatment by an electrodeposition method or the like. As an unevenness | corrugation of the surface of an aluminum member, the rolling rebar generated at the time of rolling in the case where an aluminum member is manufactured through rolling is mentioned, for example.
In the present invention, the mirror finish is not particularly limited, and a conventionally known method can be used. Examples thereof include mechanical polishing, chemical polishing, and electrolytic polishing.
Examples of the mechanical polishing include a method of polishing with various commercially available polishing cloths, and a method of combining various commercially available abrasives (for example, diamond, alumina) and a buff. Specifically, a method in which the method using an abrasive is performed by changing the abrasive used from coarse particles to fine particles over time is preferably exemplified. In this case, the final polishing agent is preferably # 1500. Thereby, the glossiness can be 50% or more (in the case of rolled aluminum, both the rolling direction and the width direction are 50% or more).

As chemical polishing, for example, “Aluminum Handbook”, 6th edition, edited by Japan Aluminum Association, 2001, p. Various methods described in 164 to 165 may be mentioned.
Further, phosphoric acid - nitric acid method, Alupol I, Alupol V, Alcoa R5, H 3 PO 4 -CH 3 COOH-Cu _{method, H 3 PO 4 -HNO 3 -CH} 3 COOH method are preferable. Among these, the phosphoric acid-nitric acid method, the H ₃ PO ₄ —CH ₃ COOH—Cu method, and the H ₃ PO ₄ —HNO ₃ —CH ₃ COOH method are preferable.
By chemical polishing, the glossiness can be made 70% or more (in the case of rolled aluminum, both the rolling direction and the width direction are 70% or more).

As electrolytic polishing, for example, “Aluminum Handbook”, 6th edition, edited by Japan Aluminum Association, 2001, p. Various methods described in 164 to 165 may be mentioned.
Moreover, the method described in US Pat. No. 2,708,655 is preferable.
“Practical Surface Technology”, vol. 33, no. 3, 1986, p. The method described in 32-38 is also preferably exemplified.
By electropolishing, the gloss can be 70% or more (in the case of rolled aluminum, both the rolling direction and the width direction are 70% or more).

  These methods can be used in appropriate combination. For example, a method of using an abrasive is preferably performed by changing the abrasive to be used from coarse particles to fine particles over time, and then performing electrolytic polishing.

By mirror finishing, for example, a surface having an average surface roughness R _{a of} 0.1 μm or less and a glossiness of 50% or more can be obtained. The average surface roughness _Ra is preferably 0.03 μm or less, and more preferably 0.02 μm or less. Further, the glossiness is preferably 70% or more, and more preferably 80% or more.
The glossiness is a regular reflectance obtained in accordance with JIS Z8741-1997 “Method 3 60 ° Specular Gloss” in the direction perpendicular to the rolling direction. Specifically, using a variable angle gloss meter (for example, VG-1D, manufactured by Nippon Denshoku Industries Co., Ltd.), when the regular reflectance is 70% or less, the incident reflection angle is 60 degrees and the regular reflectance is 70%. In the case of exceeding, the incident / reflection angle is 20 degrees.

[Anodizing process]
The anodizing treatment step in the production method of the present invention is a step of forming an anodized film in which micropores are present by performing anodizing treatment on the surface of the above-described aluminum member.
In the present invention, as the method for anodizing the surface of the aluminum member, the micropores of the present anodizing treatment are carried out before the anodizing treatment for forming micropores (hereinafter also referred to as “the present anodizing treatment”). A method of forming a depression that is the starting point of the generation of is preferable.

<Formation of depression>
The method for forming the depression is not particularly limited, and examples thereof include a self-ordering method using the self-ordering property of the anodized film, a physical method, a particle beam method, a block copolymer method, and a resist interference exposure method.

(Self-regulation method)
The self-ordering method is a method of improving the regularity by utilizing the property that the micropores of the anodized film are regularly arranged and removing the factors that disturb the regular arrangement. Specifically, high-purity aluminum is used, and an anodized film is formed at a low speed over a long period of time (for example, several hours to several tens of hours) at a voltage corresponding to the type of electrolyte, and then removed. Perform membrane treatment.
In this method, since the pore diameter depends on the voltage, a desired pore diameter can be obtained to some extent by controlling the voltage.

  As a representative example of the self-ordering method, J.A. Electrochem. Soc. Vol. 144, no. 5, May 1997, p. L128 (Non-Patent Document 6), Jpn. J. et al. Appl. Phys. Vol. 35 (1996) Pt. 2, no. 1B, L126 (Non-patent Document 7), Appl. Phys. Lett, Vol. 71, no. 19, 10 Nov 1997, p. 2771 (Non-Patent Document 8) and Non-Patent Document 1 are known. Specifically, the self-ordering method is performed under the conditions shown below.

0.3 mol / L sulfuric acid, 0 ° C., 27 V, 450 minutes (Non-patent Document 6)
0.3 mol / L sulfuric acid, 10 ° C., 25 V, 750 minutes (non-patent document 6)
0.3 mol / L oxalic acid, 17 ° C., 40 V, 600 minutes; then pore wide treatment (6 wt% phosphoric acid and 1.8 wt% chromic acid-containing solution, 60 ° C., 840 minutes) (Non-patent Document 7)
0.3 mol / L oxalic acid, 17 ° C., 40-60 V, 36 minutes; then pore-wide treatment (5 wt% phosphoric acid, 30 ° C., 70 minutes) (Non-patent Document 8)
0.04 mol / L oxalic acid, 3 ° C., 80 V, film thickness 3 μm; then pore-wide treatment (5 wt% phosphoric acid, 30 ° C., 70 minutes) (Non-patent Document 8)
0.3 mol / L phosphoric acid, 0 ° C., 195 V, 960 minutes; then pore wide treatment (10 wt% phosphoric acid, 240 minutes) (Non-patent Document 1)

Further, in the methods described in these known documents, the film removal treatment for dissolving and removing the anodic oxide film takes 12 hours or more using a mixed aqueous solution of chromic acid and phosphoric acid at about 50 ° C. Yes. In addition, since the starting point of ordering will be destroyed and disturb | disturbed if it processes using the boiled aqueous solution, it uses without boiling.
Since the regularity of the self-ordered anodic oxide film becomes higher as it gets closer to the aluminum part, the film is removed once, and the bottom part of the anodic oxide film remaining on the aluminum part is exposed to the surface to form regular depressions. obtain. Therefore, in the film removal treatment, aluminum is not dissolved, but only the anodized film that is aluminum oxide is dissolved.

  The self-ordered anodizing treatment used in the present invention may be, for example, a method of energizing an aluminum member as an anode in a solution having an acid concentration of 1 to 10% by mass. As a solution used for the anodizing treatment, sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, amidosulfonic acid and the like can be used alone or in combination of two or more.

The conditions of the self-ordering anodizing treatment cannot be determined unconditionally because they vary depending on the electrolyte used. In general, the electrolyte concentration is 1 to 10% by mass, the solution temperature is 0 to 20 ° C., and the current density. It is appropriate that the pressure is 0.1 to 10 A / dm ² , the voltage is 10 to 200 V, and the electrolysis time is 2 to 20 hours.
The film thickness of the self-ordered anodic oxide film is preferably 10 to 50 μm.

In the present invention, the self-ordering anodizing treatment is preferably 1 to 16 hours, more preferably 2 to 12 hours, and further preferably 2 to 7 hours.
The film removal treatment is preferably 0.5 to 10 hours, more preferably 2 to 10 hours, and further preferably 4 to 10 hours.

  In this way, after forming the anodized film by the self-ordering method, this is dissolved and removed, and when the anodizing process described later is performed again under the same conditions, a substantially straight micropore is obtained. It is formed substantially perpendicular to the film surface.

(Physical method)
Examples of the physical method include a method using press patterning. Specifically, a method of forming a depression by pressing a substrate having a plurality of protrusions on the surface thereof against the aluminum surface can be mentioned. For example, a method described in JP-A-10-121292 can be used.
Another example is a method in which polystyrene spheres are arranged in a dense state on the aluminum surface, SiO ₂ is vapor-deposited thereon, then the polystyrene spheres are removed, and the substrate is etched using the vapor-deposited SiO ₂ as a mask to form depressions. It is done.

(Particle beam method)
The particle beam method is a method in which a hollow is formed by irradiating the aluminum surface with a particle beam. The particle beam method has an advantage that the position of the depression can be freely controlled.
Examples of the particle beam include a charged particle beam, a focused ion beam (FIB), and an electron beam.
As the particle beam method, for example, a method described in JP-A-2001-105400 can be used.

(Block copolymer method)
The block copolymer method is a method in which a block copolymer layer is formed on an aluminum surface, a sea-island structure is formed in the block copolymer layer by thermal annealing, and then an island portion is removed to form a depression.
As a block copolymer method, the method described in Unexamined-Japanese-Patent No. 2003-129288 can be used, for example.

(Resist interference exposure method)
The resist interference exposure method is a method in which a resist is provided on an aluminum surface, and the resist is exposed and developed to form a recess penetrating to the aluminum surface in the resist.
As the resist interference exposure method, for example, a method described in JP 2000-315785 A can be used.

Among the methods for forming the various depressions described above, the self-ordering method, the FIB method, and the resist interference exposure method are desirable because they can be uniformly formed over a large area of about 10 cm square or more.
Furthermore, the self-ordering method is most preferable in consideration of manufacturing costs. The FIB method is also preferable in that the arrangement of micropores can be freely controlled.

  The depth of the depression formed is preferably about 10 nm or more. The width is preferably equal to or less than the desired pore diameter.

<This anodizing treatment>
In the present invention, a recess is formed on the aluminum surface as desired, and then an anodized film having micropores is formed by the present anodizing treatment.

For this anodizing treatment, a conventionally known method can be used.
Specifically, a method of repeatedly turning on and off the current intermittently while keeping the DC voltage constant, and a method of repeatedly turning on and off the current while intermittently changing the DC voltage can be suitably used. According to these methods, fine micropores are generated in the anodic oxide film, which is preferable in that uniformity is improved particularly when sealing treatment is performed by electrodeposition.
In the above-described method of intermittently changing the voltage, it is preferable to decrease the voltage sequentially. As a result, the resistance of the anodized film can be lowered, and can be made uniform when the electrodeposition treatment is performed later.

When this anodizing treatment is performed at a low temperature, the arrangement of the micropores becomes regular and the pore diameter becomes uniform.
The film thickness of the anodized film is preferably 0.5 to 10 times the pore diameter, more preferably 1 to 8 times, and more preferably 1 to 5 times in terms of ease of metal filling. Further preferred.
The pore diameter is preferably 10 nm or more when an electrodeposition treatment is subsequently performed as a sealing treatment.
Therefore, for example, it is one of the preferable embodiments that the film thickness of the anodic oxide film is 0.1 to 1 μm and the average pore diameter of the micropores is 10 to 500 nm.

It is preferable that the variation coefficient of the pore diameter of the micropore is 5 to 20%. When the pore diameter variation coefficient is in the above range, the filling efficiency in the sealing treatment described later is increased, and the metal particles come close to each other, so that the localized plasmon resonance is increased.
Here, the pore diameter variation coefficient (CV: Coefficient of Variation) is an index of pore diameter variation and is defined by the following equation.

  (Variation coefficient of pore diameter) = (Standard deviation of pore diameter) / (Average of pore diameter)

The average pore density of the micropores is preferably 50-1500 / μm ² .

The area ratio occupied by the micropores is preferably 20 to 50%.
The area ratio occupied by the micropore is a ratio of the total area of the opening of the micropore to the area of the aluminum surface. In the calculation of the area ratio occupied by the micropores, the micropores include those that are not filled with metal and those that are not filled with metal. Specifically, it is obtained by measuring the surface porosity before the sealing treatment.

<Pore wide processing>
In the present invention, after this anodizing treatment, if necessary, the aluminum member is immersed in an aqueous acid solution or an aqueous alkaline solution to dissolve the anodized film and perform pore-wide treatment for expanding the pore diameter of the micropore. Is preferred.
Thereby, it becomes possible to selectively deposit the inside of the micropores by dissolving the barrier film on the bottom portion of the micropores of the anodized film.

When an aqueous acid solution is used for the pore wide treatment, it is preferable to use an aqueous solution of an inorganic acid such as sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid, or a mixture thereof. The concentration of the acid aqueous solution is preferably 1 to 10% by mass. The temperature of the acid aqueous solution is preferably 25 to 40 ° C.
When an alkaline aqueous solution is used for the pore-wide treatment, it is preferable to use an aqueous solution of at least one alkali selected from the group consisting of sodium hydroxide, potassium hydroxide and lithium hydroxide. The concentration of the alkaline aqueous solution is preferably 0.1 to 5% by mass. The temperature of the alkaline aqueous solution is preferably 20 to 35 ° C.
Specifically, for example, 50 g / L, 40 ° C. phosphoric acid aqueous solution, 0.5 g / L, 30 ° C. sodium hydroxide aqueous solution or 0.5 g / L, 30 ° C. potassium hydroxide aqueous solution is preferably used. .
The immersion time in the acid aqueous solution or the alkali aqueous solution is preferably 8 to 60 minutes, more preferably 10 to 50 minutes, and further preferably 15 to 30 minutes.

<Other processing>
Further, other processes can be performed as necessary.
For example, when the structure of the present invention is used as a sample stage and an aqueous solution is dropped to form a film, a hydrophilic treatment may be performed in order to reduce the contact angle with water. The hydrophilic treatment can be performed by a conventionally known method.
In addition, when the structure of the present invention is used as a sample stage to target a protein that is denatured or decomposed with an acid, the acid remaining on the aluminum surface is neutralized. In order to achieve this, a neutralization treatment may be performed. The neutralization treatment can be performed by a conventionally known method.

[Sealing process]
The sealing treatment step in the production method of the present invention is a step of filling the micropores with metal after the above-described anodizing treatment step.
In the present invention, the metal is not particularly limited as long as it is an element composed of a metal bond having free electrons and has conductivity, but is preferably a metal in which plasmon resonance has been confirmed.
Specifically, copper (Cu), nickel (Ni), chromium (Cr), zinc (Zn), gold (Au), silver (Ag), platinum (Pt), palladium (Pd) and the like can be mentioned (plating). Textbook, 2001, Nikkan Kogyo Shimbun, p.63-153 (Non-Patent Document 9)).
Among these, copper, nickel, and gold are preferable because of high conductivity and high uniformity, and nickel and gold are more preferable from the viewpoint of adhesion with metal particles that are provided later.
In addition, it is known that plasmon resonance is likely to occur in copper, nickel, gold, silver, and platinum (Hyundai Kagaku, September 2003, p. 20-27 (Non-Patent Document 10)). Gold and silver are preferable from the viewpoint of easy deposition and production of colloidal particles.

The method for the sealing treatment is not particularly limited, and a conventionally known method can be used.
For example, an electrodeposition method; a method of applying a dispersion of metal colloidal particles to an aluminum member having an anodized film and drying; and an electroless plating method are preferable. The metal is preferably a single particle or an aggregate.

<Electrodeposition method>
As the electrodeposition method, a conventionally known method can be used. Specifically, for example, in the case of gold electrodeposition method, a dispersion of 30 ° C. containing H ₂ SO ₄ of HAuCl ₄ and 7 g / L of 1 g / L, the aluminum member is immersed, 11V constant voltage ( (Adjusted with slidac), electrodeposition treatment for 5 to 6 minutes; dispersion containing 6 g / L potassium dicyanoaurate (I) and 10 g / L chelating agent (EDTA) (liquid temperature 40 ° C., Examples include a method of immersing the support in pH 6), using a high-purity platinum plate as a counter electrode, and performing an electrodeposition treatment for 5 to 6 minutes under the condition of a current density of 0.1 A / dm ² .
As the electrodeposition method, Hyundai Kagaku, January 1997, p. An example using copper, tin and nickel is described in detail in 51-54 (Non-Patent Document 11), and this method can also be used.

<Method using metal colloidal particles>
The dispersion used in the method using metal colloidal particles can be obtained by a conventionally known method. For example, it can be obtained by a method for producing fine particles by a low vacuum evaporation method or a method for producing a metal colloid that reduces an aqueous solution of a metal salt.
The metal colloidal particles preferably have an average particle size of 1 to 200 nm, more preferably 1 to 100 nm, and even more preferably 2 to 80 nm.
As the dispersion medium used in the dispersion, water is preferably used. In addition, solvents that can be mixed with water, for example, alcohols such as ethyl alcohol, n-propyl alcohol, i-propyl alcohol, 1-butyl alcohol, 2-butyl alcohol, t-butyl alcohol, methyl cellosolve, and butyl cellosolve A mixed solvent with water can also be used.

  In the method using metal colloidal particles, the coating method is not particularly limited, and examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.

As the dispersion liquid used in the method using metal colloid particles, for example, a gold colloid particle dispersion liquid and a silver colloid particle dispersion liquid are preferably used.
As the dispersion of colloidal gold particles, for example, those described in JP-A-2001-89140 and JP-A-11-80647 can be used. Commercial products can also be used.
The dispersion of silver colloidal particles preferably contains silver and palladium alloy particles in that they are not affected by the acid eluted from the anodized film. In this case, the palladium content is preferably 5 to 30% by mass.

  After applying the dispersion, it is appropriately washed with a solvent such as water. As a result, only the particles filled in the micropores remain in the anodized film, and the particles not filled in the micropores are removed.

<Electroless plating method>
As the electroless plating method, a conventionally known method can be used. If the diameter of the micropore of the anodized film is 300 nm or more, it can be used. As the electroless plating method, a plating method using a gold cyan complex and a reducing agent is preferably exemplified.
Although the mechanism of this electroless plating method has not been elucidated, since the metal and the reducing agent easily react with each other, the aluminum ingot is exposed when the barrier film is reduced, and the exposed aluminum ingot and gold cyanide are exposed. By the substitution reaction with the complex, aluminum and gold are substituted, and the surface of the aluminum ingot is covered with gold. It is considered that once the surface is covered with gold, gold grows by autocatalytic reaction, so that it becomes possible to fill the micropores of the anodized film without electrolysis. For this reason, the treated anodic oxide film has high conductivity and becomes uniform.

In the present invention, the adhesion amount of the metal after the sealing treatment is preferably 100 to 500 mg / m ^2.
The surface porosity after the sealing treatment is preferably 20% or less. The surface porosity after the sealing treatment is a ratio of the total area of the openings of the unfilled micropores to the area of the aluminum surface. When the surface porosity is within the above range, stronger localized plasmon resonance is obtained.

  When the pore diameter is 50 nm or more, a method using metal colloidal particles is preferably used. Moreover, when a pore diameter is less than 50 nm, an electrodeposition method is used suitably. A method of combining both is also preferably used.

[Surface treatment process]
The surface treatment step in the production method of the present invention is a step of removing a part of the upper layer surface of the anodized film after the sealing treatment step described above to make the average surface roughness ( _Ra ) of the surface 30 nm or less. It is.
In the present invention, the removal of a part of the upper surface of the anodic oxide film is not particularly limited as long as the average surface roughness (R _a ) of the surface after the removal is 30 nm or less. It is preferable to remove 20 to 80% of the thickness of the anodized film before removal.
In the present invention, the removal of a part of the upper surface of the anodized film is at least one method selected from the group consisting of mechanical polishing, chemical dissolution described later, and film removal by ion beam in vacuum. The removal is preferably performed by mechanical polishing, particularly chemical mechanical polishing (CMP).

<Mechanical polishing>
The mechanical polishing is not particularly limited, and a method used for the mirror finish processing described above can be used. Of these, chemical mechanical polishing (CMP) is preferable.
As the CMP method, a known CMP polishing technique frequently used for polishing a semiconductor silicon wafer can be used.
Here, the CMP polishing technique is more accurate than the conventional polishing technique using a conventional general-purpose polishing disk, has a high accuracy of the polishing disk itself, has excellent sample holding method and stability, and has a small abrasive particle size. The liquid during polishing dissolves the film.
Specifically, with a general-purpose polishing machine, it is difficult to control parallelism, sample holding, etc. on the order of nanometers, and with normal abrasives used for general-purpose polishing machines, particles are coarse. Too much (average particle size 0.06 to 10 μm), the micropores present in the anodized film are destroyed, and smoothing on the nanometer order is difficult. On the other hand, in a polishing machine for CMP in which ultrafine particles having a particle size on the order of submicron (average particle diameter 0.01 to 1 μm) can be used as an abrasive, the structure of the anodized film is not destroyed. A part of the upper layer of the oxide film can be easily removed.
In the CMP method, the thickness of the micropore wall present in the anodized film is preferably 10 to 100 nm when sufficiently filled with metal.

  As the CMP method, CMP Science, 1999, Science Forum, p. 72-98, p. 123-176 (Non-Patent Document 12) describes an example using an apparatus and an abrasive in detail, and this method can also be used.

<Chemical dissolution (chemical polishing)>
The chemical dissolution method is a method of dissolving the anodized film with a chemical (solution) having a property of dissolving aluminum oxide.
Specific examples of such chemicals (solutions) include sulfuric acid, chromic acid, oxalic acid, phosphoric acid, chromic phosphoric acid, etc., and these may be used alone or in combination of two or more. May be used in combination.
Dissolution by the chemical dissolution method proceeds so as to selectively remove portions that are not completely filled with metal and enlarge the micropores, so that the thickness of the anodized film itself hardly changes. The dissolution rate is usually about 10 nm / min to 100 nm / min.
In the chemical dissolution method, the thickness of the micropore wall present in the anodized film is preferably 50 to 500 nm.
Moreover, the method used for the mirror surface finishing process mentioned above can also be used.

<Removal of film by ion beam in vacuum>
The film removal by the ion beam in vacuum is a method of removing an object (a part of the upper surface of the anodic oxide film) on an atomic order by irradiating ions in a vacuum. Such a method provides a very uniform and clean surface, but generally the equipment is expensive and large areas cannot be applied to processing, which may result in poor manufacturing efficiency.
For film removal by ion beam in vacuum, practical precision processing and measurement technology, 2003, NTS, p. An example is described in detail in 193-210 (Non-Patent Document 13), and this method can also be used.

The film thickness after mechanical polishing, chemical dissolution, and film removal by ion beam in vacuum can be measured by SEM, and the average surface roughness (R _a ) is measured by an atomic force microscope (AFM: (Atomic Force Microscope).
Specifically, as shown in the examples described later, the film thickness of the anodized film was cut out of a part of the sample before and after removing the film, bent at 90 degrees, and the cross section of the cracked part was measured with FE-SEM. Observed and measured at an appropriate magnification, and the anodized film after the surface treatment is measured with a cantilever.

[Electrodeposition process]
The electrodeposition step in the production method of the present invention is a step of further forming metal particles by electrodeposition on the metal filled by the sealing treatment after the surface treatment step described above.
In the present invention, examples of the metal particles include metal particles exemplified in the above-described sealing treatment step. Gold particles, silver particles, and nickel particles are preferable. From the viewpoint of high conductivity and resistance to oxidation. More preferred are gold particles.
As the electrodeposition method described in the sealing treatment step, a conventionally known method can be used. In particular, when gold particles are formed, as described above, 1 g / L. A method in which an aluminum member is immersed in a dispersion at 30 ° C. containing HAuCl ₄ and 7 g / L of H ₂ SO ₄ and electrodeposition is performed at a constant voltage of 11 V (adjusted with a slidac) for 5 to 6 minutes; 6 g / The support is immersed in a dispersion (liquid temperature 40 ° C., pH 6) containing L potassium dicyanogold (I) and 10 g / L chelating agent (EDTA), and a high-purity platinum plate is used as a counter electrode. , A method of performing electrodeposition treatment for 5 to 6 minutes under the condition of a current density of 0.1 A / dm ² can be used. In addition, the same effect can be obtained by using a nickel electrodeposition method (nickel electrodeposition).

Here, as the nickel electrodeposition, the plating textbook, 2001, Nikkan Kogyo Shimbun, p. 81 to 89 (Non-patent Document 9), a known electrodeposition method using nickel can be used.
Specifically, (1) nickel ion source (generally containing about 1/100 cobalt) nickel sulfate 50 to 400 g / L, preferably 150 to 390 g / L, more preferably 220 to 380 g / L; 10 to 100 g / L of nickel chloride, preferably 20 to 80 g / L, more preferably 30 to 60 g / L; Moreover, (2) As a pH adjuster, boric acid 15-45 g / L which can adjust PH to 3-6, Preferably it is 20-45 g / L, More preferably, 30-40 g / L can be used. Further, (3) electrolysis conditions are preferably a temperature of 25 to 65 ° C., a current density of 0.5 to 10 A / dm ² , and a voltage of 20 to 120 V. (4) As the anode electrode material, high purity nickel (99.99% or more), high purity platinum (99.9% or more), titanium plated with platinum (99.9% or more), etc. can be used. However, high purity nickel is most desirable.

In the structure of the present invention, the average particle diameter of the metal particles electrodeposited by such an electrodeposition process is larger than the average pore diameter of the micropores present in the anodized film, and the average between adjacent micropores It is smaller than the pore period which is the center interval.
Here, the average particle diameter of the metal particles is obtained by observing the surface of the structure after the electrodeposition process with a field emission scanning electron microscope (FE-SEM), measuring the diameter of 100 particles in an appropriate region, It can be calculated from the average value.
In addition, the pore period can be calculated from an average value obtained by observing the surface of the structure before the electrodeposition process with an FE-SEM, measuring the center distance between adjacent micropores for 100 appropriate regions, and the average value thereof. it can.

Schematic cross-sectional view of the film surface after each process when the above-described sealing treatment process, surface treatment process and electrodeposition process are performed on the anodized film having micropores formed by the above-described anodizing process Is shown in FIG.
FIG. 1A is a schematic cross-sectional view of an anodized film 1 having micropores 2 formed by an anodizing process.
FIG. 1B is a schematic cross-sectional view of the anodized film 1 in a state where the metal 3 is filled in the micropores 2 by a sealing treatment process (electrodeposition method). As shown in FIG. 1 (B), the filling of the metal 3 by the sealing treatment step is not performed uniformly for all the micropores 2, and there are micropores that are mostly filled, Some micropores remain slightly filled and remain largely voids (prominent in comparison between the center micropore and the right micropore in FIG. 1B). Such uneven filling is considered to be due to uneven thickness of the insulating barrier film present at the bottom of the anodized film 1.
FIG. 1C is a schematic cross-sectional view of the anodized film 1 in which _a part of the upper layer surface of the anodized film 1 is removed by the surface treatment process, and the surface is set to a predetermined average surface roughness ( _Ra ). is there. In the present invention, by this surface treatment step, the metal 3 is filled to the surface in each micropore 2, and the metal filling unevenness generated in the above-described sealing treatment step can be reduced.
FIG. 1D is a schematic cross-sectional view of an anodized film 1 in which a metal 4 is further formed on a metal 3 in a micropore 2 by an electrodeposition process. As shown in FIG. 1D, in the electrodeposition process after the surface treatment process is performed, the metal 4 is uniformly formed in a particle shape rising from the surface of the anodized film 1.
On the other hand, FIG. 1E is a schematic cross-sectional view of the anodized film 1 when the electrodeposition process is performed without performing the surface treatment process. If the electrodeposition process is performed without the surface treatment process and the metal filling unevenness in the sealing process, the metal 4 is formed on the metal 3 in the micropore, but the shape thereof varies. All the metals 4 do not have a raised particle shape as shown in FIG.

[Microstructure]
The structure of the present invention is a structure obtained by a manufacturing method comprising the above-described anodizing treatment step, sealing treatment step, surface treatment step and electrodeposition step, and is a micropore present in the anodized film. A structure having an average pore diameter of 10 to 500 nm, a pore diameter variation coefficient of 5 to 20%, and an average particle diameter of the metal particles larger than the average pore diameter and smaller than a pore period. is there.
FIG. 2 is a schematic cross-sectional view showing the surface of the structure of the present invention that has been subjected to sealing treatment by an electrodeposition method. In the structure 10 shown in FIG. 2, the micropores 14 of the anodized film 12 are filled with the metal 16, and the surface of the metal 17 is made to pass through the surface treatment process and the electrodeposition process. It rises from the surface of and becomes particulate.
FIG. 3 is a schematic cross-sectional view showing the surface of the structure of the present invention that has been sealed by a method using metal colloid particles. In the structure 20 shown in FIG. 3, the micropores 24 of the anodic oxide film 22 are filled with the metal 26 as in the structure 10, and the metal 27 is subjected to the surface treatment process and the electrodeposition process. The surface rises from the surface of the anodized film 22 and is in the form of particles. There may be a case where a gap remains in the micropore 24 (this is remarkable in the micropore on the right side in FIG. 3).

In general, the interval between the metal particles is preferably shorter in order to increase the Raman enhancement effect, but the optimum interval is affected by the size and shape of the metal particles.
Therefore, although the interval between the metal particles cannot be determined unconditionally, it is generally preferably in the range of 1 to 400 nm, more preferably 5 to 300 nm, and still more preferably 10 to 200 nm. Within the above range, the Raman enhancement effect is increased.
Here, the “interval between metal particles” is the shortest distance between the surfaces of adjacent particles.

<Raman enhancement effect by localized plasmon resonance>
The Raman enhancement effect is a phenomenon in which the Raman scattering intensity of the molecules adsorbed on the metal is enhanced by about 10 ⁵ to 10 ⁶ times, and is called surface enhanced Raman scattering (SERS: Surface Enhanced Raman Scattering). And the said nonpatent literature 9 describes that a Raman enhancement effect is acquired by the localized plasmon resonance using metal particles, such as gold | metal | money, silver, copper, platinum, nickel.

FIG. 4 is a schematic cross-sectional view showing the surface of the structure of the present invention shown in FIG. 2, which is used as a sample stage for Raman spectroscopic analysis.
When the sample for Raman spectroscopic analysis is a hydrophilic substance, it is preferable to use the structure 10 in which the surface of the anodized film 12 is hydrophobic, and when the sample for Raman spectroscopic analysis is a hydrophobic substance. It is preferable to use the structure 10 in which the surface of the anodized film 12 is hydrophilic. By doing so, as shown in FIG. 4, the specimen 18 selectively and uniformly adheres to the surface of the particulate metal 17.

  When the structure of the present invention is used for a sample stage for Raman spectroscopic analysis, the signal intensity of Raman scattering becomes sufficiently large and the reproducibility is excellent. This is because by removing a part of the anodized film, there are many metal particles protruding in a raised particle shape (mushroom shape) as shown in FIG. Since it becomes easy to control the space | interval with a metal particle in the optimal range, it is thought that signal strength becomes large and reproducibility also becomes favorable.

  The method for using the structure of the present invention (Raman spectroscopic sample stage) is the same as the conventional method for using the Raman spectroscopic sample stage. Specifically, by irradiating the sample stage for Raman spectroscopic analysis with light and measuring the Raman scattering intensity of the reflected or transmitted light, the characteristics of the substance in the vicinity of the metal held on the sample stage Is detected.

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these.
(Examples 1 to 27 and Comparative Examples 1 and 2)
1. As shown in Table 1, each substrate is subjected to a mirror finishing process, formation of dents, main anodizing process, pore-wide process, sealing process, surface process and electrodeposition process. Got. In Table 1, “2-1”, “2-2”, etc. in the column of self-ordering anodizing treatment represent the conditions shown in Table 2, and “4-1” in the column of this anodizing treatment. , “4-2”, etc. represent the conditions shown in Table 4, “1”, “2”, etc. in the sealing process column indicate sealing process 1, sealing process 2, etc., which will be described later, and “-”. Indicates that the corresponding processing has not been performed.

  Hereinafter, the substrate and each process will be described.

(1) Substrate For manufacturing the structure, the following substrate 1 was used.
Substrate 1: High-purity aluminum, manufactured by Wako Pure Chemical Industries, Ltd., purity 99.99 mass%, thickness 0.4 mm

(2) Mirror surface finishing treatment The substrate 1 was subjected to the following mirror finishing treatment.
<Mirror finish processing>
By performing polishing using a polishing cloth, buffing and electrolytic polishing in this order, a mirror finish was applied. After buffing, it was washed with water.
Polishing using a polishing cloth uses a polishing machine (Struers Abramin, manufactured by Marumoto Kogyo Co., Ltd.) and a water-resistant polishing cloth (commercially available), and the number of the water-resistant polishing cloth is # 200, # 500, # 800, # 1000 and The change was made in the order of # 1500.
The buffing was performed using a slurry-like abrasive (FM No. 3 (average particle size 1 μm) and FM No. 4 (average particle size 0.3 μm), both manufactured by Fujimi Incorporated).
The electrolytic polishing was performed for 2 minutes using an electrolytic solution (temperature: 70 ° C.) having the following composition, using the anode as a substrate and the cathode as a carbon electrode at a constant current of 130 mA / cm ² . As a power source, GP0110-30R (manufactured by Takasago Seisakusho) was used.

<Electrolyte composition>
-660 mL of 85% by mass phosphoric acid (reagent manufactured by Wako Pure Chemical Industries, Ltd.)
・ Pure water 160mL
・ Sulfuric acid 150mL
・ Ethylene glycol 30mL

(3) Formation of depressions A depression serving as a starting point for micropore formation was formed on the surface of the substrate 1 that had been mirror-finished by the following self-ordering method in the anodizing process described later.

<Self-regulation method>
Self-ordered anodizing treatment under any condition selected from the conditions (2-1 to 2-10) of the type, concentration and temperature, voltage, current density and treatment time shown in Table 2 And an anodized film having a film thickness shown in Table 2 was formed. In the self-ordering anodizing treatment, NeoCool BD36 (manufactured by Yamato Scientific Co., Ltd.) is used as a cooling device, Pear Stirrer PS-100 (manufactured by EYELA) is used as a stirring and heating device, and GP0650-2R (manufactured by Takasago Seisakusho) is used as a power source. It was.

  In Table 2, reagents manufactured by Kanto Chemical Co., Inc. were used for phosphoric acid, oxalic acid and sulfuric acid. The current density showed a stable value.

Next, film removal treatment for dissolving the anodized film was performed by immersing the substrate on which the anodized film was formed under the conditions shown in Table 3 in a treatment solution.
Further, the film removal rate was calculated from the amount of change with time in the film thickness of the anodized film and the processing time, and is shown in Table 3. The film thickness of the anodic oxide film after the film removal treatment was 0.1 μm or less.

<Calculation of film removal rate>
During the film removal process, the substrate sampled every hour is bent, and the side surface (fracture surface) of the cracked part is compared with 12V using an ultra-high resolution SEM (Hitachi S-900, manufactured by Hitachi, Ltd.) The film thickness was measured with a low acceleration voltage and without performing a vapor deposition treatment for imparting conductivity. Sampling was performed by randomly sampling 10 points at a time, and the average film thickness was determined. The error in film thickness was in the range of ± 10%.

  In Table 3, reagents manufactured by Kanto Chemical Co., Inc. were used for 85% by mass phosphoric acid and chromic anhydride.

(4) Main anodizing treatment The main anodizing treatment was applied to the substrate on which the depressions were formed. This anodizing treatment is performed by immersing the substrate in the electrolytic solution and selected from the conditions (4-1 to 4-9) of the type, concentration and temperature of the electrolytic solution and the first voltage shown in Table 4. It was performed by performing electrolytic treatment once or a plurality of times under any condition.
When the electrolytic treatment is performed a plurality of times, the electrolysis is interrupted when the initial value V ₀ of the constant voltage is reached for the first time, and the initial set value 0.9 × V ₀ [V] of the constant voltage is reached the second time. Then, the electrolysis is interrupted, and the third time, the electrolysis is interrupted when the constant voltage initial setting value 0.8 × V ₀ [V] is reached. The nth time, the constant voltage initial setting value {1-0 .1 × (n−1)} × V ₀ was repeated several times to stop electrolysis.
Further, the thickness of the anodized film was measured by the same method as described above, and the increment was shown in Table 4.

(5) Pore-wide treatment The pore-wide treatment was performed by immersing the substrate in a phosphoric acid aqueous solution (liquid temperature 30 ° C.) having a concentration of 50 g / L for 30 minutes.

(6) Sealing process The sealing process performed any of the following sealing processes 1-9.
(I) Sealing treatment 1 (method using Au colloidal particles)
Add 1.5 mL of 1 wt% citric acid aqueous solution to 1.5 mL of 0.05 wt% HAuCl ₄ aqueous solution, gradually heat from room temperature using an alcohol lamp, and stop heating in a state of turning reddish purple The support was immersed in a colloidal gold particle dispersion (average colloidal particle size of 120 nm) obtained by cooling to room temperature for 1 minute, washed with water and dried.

(Ii) Sealing treatment 2 (Au electrodeposition method)
The substrate is immersed in a plating bath (pH 10, liquid temperature 75 ° C.) having a bath composition shown in Table 5, a high-purity platinum plate is used as a counter electrode, and a current density of 0.1 A / dm ² is used. Electrodeposition treatment was performed for a minute.

(Iii) Sealing treatment 3 (Cu electrodeposition method)
A support containing 20 g / L cuprous cyanide, 14 g / L copper, 27 g / L NaCN, and 34 g / L KCN (liquid temperature 40 ° C., pH 10.2) Was immersed, and a high-purity electrolytic copper plate was used as a counter electrode, and electrodeposition treatment was performed for 5 to 6 minutes under the condition of a current density of 1.0 A / dm ² .

(Iv) Sealing treatment 4 (Ni electrodeposition method)
The support is immersed in a dispersion (liquid temperature 40 ° C., pH 3) containing 220 g / L nickel sulfate, 30 g / L nickel chloride, and 30 g / L boric acid, and a high-purity nickel plate as a counter electrode Was used for electrodeposition treatment at a current density of 2.0 A / dm ² for 5 to 6 minutes.

(V) Sealing treatment 5 (Cr electrodeposition method)
The support was immersed in a dispersion (liquid temperature 50 ° C., pH 2) containing 70 g / L chromic anhydride, 0.7 g / L sulfuric acid, and 0.7 g / L Na ₂ SiF ₆ , A lead plate was used as the counter electrode, and electrodeposition treatment was performed for 5 to 6 minutes under the condition of a current density of 30.0 A / dm ² .

(Vi) Sealing treatment 6 (Zn electrodeposition method)
The support was immersed in a dispersion (liquid temperature 20 ° C., pH 5) containing 31 g / L ZnCl ₂ , 15 g / L zinc, 210 g / L KCl, and 25 g / L boric acid, a high-purity platinum plate as the counter electrode, at a current density of 1.0A / dm ^2, was treated for 5-6 minutes electrodeposition.

(Vii) Sealing treatment 7 (Ag electrodeposition method)
The support is immersed in a dispersion (liquid temperature 20 ° C., pH 11) containing 30 g / L AgCN, 24 g / L silver, 50 g / L KCN, and 15 g / L K ₂ CO _3. Then, carbon was used as a counter electrode, and electrodeposition treatment was performed for 5 to 6 minutes under the condition of a current density of 0.5 A / dm ² .

(Viii) Sealing treatment 8 (Pt electrodeposition method)
The support is immersed in a dispersion (liquid temperature: 65 ° C., pH 2) containing 20 g / L of platinum and 300 g / L of hydrochloric acid (using H ₂ PtCl ₆ as a reagent), and a high-purity platinum plate as a counter electrode Was used for electrodeposition treatment at a current density of 15.0 A / dm ² for 5 to 6 minutes.

(Ix) Sealing treatment 9 (Pd electrodeposition method)
The support is immersed in a dispersion (solution temperature: 43 ° C., pH: 9) containing 4 g / L of palladium, 90 g / L of ammonium nitrate, and ammonia (pH adjusting reagent), and a high-purity platinum plate is used as a counter electrode. Then, electrodeposition treatment was performed for 5 to 6 minutes under the condition of a current density of 0.5 A / dm ² .

(8) Surface treatment The surface treatment performed any of the following film removal methods A to C.
(I) Film formation removal method A (mechanical polishing method)
Diamond slurry (# 2400000, particle size 0.1 μm) and aluminum oxide (particle size 0.05 μm) were used in this order for 30 seconds and 10 seconds, respectively, for ultra-precision polishing equipment (MA-200D, manufactured by Musashino Electronics Co., Ltd.) Was polished at a rotational speed of 50 rpm.
The polishing is performed by appropriately spraying a 3% by mass phosphoric acid aqueous solution with a spray, visually observing the polished surface, and when the color of the filled metal changes from a glossy color (for example, when the filled metal is gold, The polishing end time was set with reference to the time when the color changed from gold to magenta.

(Ii) Film removal method B (chemical dissolution)
B-1: It was immersed for 15 minutes (900 seconds) in 5 mass% phosphoric acid aqueous solution with a liquid temperature of 30 ° C. to dissolve the surface layer.
B-2: A surface layer was dissolved by immersing in a chromic acid aqueous solution (85% by mass phosphoric acid 118 g, chromic anhydride 30 g, pure water 150 g) for 5 minutes (300 seconds) at a liquid temperature of 30 ° C.
In any case, the dissolution was performed until the surface of the dissolution was visually observed and the color of the filled metal changed from the glossy color.

(Iii) Film removal method C (film removal by ion beam in vacuum)
Using a flat ion milling device (E-3200, manufactured by Hitachi High-Tech Co., Ltd.), it is removed by irradiating while visually observing with an attached optical microscope under conditions of an irradiation area of 5 mmφ, an ion gun of 5 kV, and a vacuum of 3 × 10 ⁻⁴ Pa did.
Irradiation was performed until the color of the filled metal changed from the glossy color.

(9) Electrodeposition The metal particles described in Table 1 were electrodeposited by the same method as the sealing treatments 2 to 9 described above. The electrodeposition time and the average particle size of the metal particles are shown in Table 1.
Here, the average particle diameter of the metal particles is determined by observing the surface of the structure after the electrodeposition process with FE-SEM (S-800, manufactured by Hitachi, Ltd.) and measuring the diameter of 100 particles in an appropriate region. It calculated from the average value.

About the obtained structure, the average pore diameter of micropores and the variation coefficient of the pore diameter were measured by image analysis of SEM surface photographs observed with FE-SEM (S-800, manufactured by Hitachi, Ltd.). The method of image analysis is shown below.
Execute binarization (Otsu's method) using image processing software (Image Factory, manufactured by Asahi High-Tech), and then perform binarized image shape analysis in the order of black hole filling, black expansion and black contraction. did. Next, I input the length shown in the photo using the measuring bar. Further, the shape features were extracted, the black count and the equivalent circle diameter were output, the average pore density was calculated from the black count number, and the average pore diameter and the standard deviation were calculated from the equivalent circle diameter distribution. Further, the standard deviation was divided by the average pore diameter to obtain a pore diameter variation coefficient.
These results are shown in Table 6.

Moreover, about the obtained structure, the average center space | interval (pore period) between adjacent micropores is observed in FE-SEM (S-800, Hitachi Ltd. make), and the center space | interval between adjacent micropores is observed. Was measured for 100 pieces in an appropriate region and calculated from the average value.
These results are shown in Table 6.

Further, the film thickness (nm) of the anodized film after removal by the surface treatment (removal methods A to C) and the removal rate (%) indicating what percentage of the thickness before removal are removed are as shown below. Measurement was performed using FE-SEM, and R _a (nm) on the surface of the anodized film after removal was measured using AFM under the following conditions. These results are shown in Table 6.
(1) Measurement of film thickness and removal rate of anodic oxide film after film removal Part of the sample before and after film removal was cut out, bent at 90 degrees, and the cross section of the cracked part was FE-SEM (S-800, Hitachi (Manufactured by Seisakusho Co., Ltd.) at an appropriate magnification, the film thickness of the anodized film is measured, and the removal rate is calculated from the film thickness before and after film removal.
(2) the R _a of the anodized film after the measurement surface treatment of R _a by AFM, under the following conditions, measured by the cantilever (SI DF40P, manufactured by Seiko Instruments). Location unfilled often and R _a is increased, R _a is lower when being almost filled.
・ Scanning area: 3000nm
・ Scanning frequency: 0.5Hz
Amplitude decay rate: -0.16
・ I gain: 0.0749
・ P gain: 0.0488
・ Q curve gain: 2.00
・ Excitation voltage: 0.044V
・ Resonance frequency: 318.5 kHz
・ Measurement frequency: 318.2 kHz
・ Vibration amplitude: 0.995V
・ Q value: around 460

2. Measurement of Raman enhancement effect Each structure obtained 3 × 10 ⁻⁷ mol / L Rhodamine 6G aqueous solution (Kanto Chemical Co., Ltd. reagent) and 0.1 mol / L NaCl aqueous solution (Kanto Chemical Co., Ltd. reagent) after application to the surface of the body, using a Raman spectrophotometer (T64000, manufactured by Horiba), excitation wavelength of 488 nm, under conditions of Raman shift measurement range 1800～800Cm ^-1, it was measured Raman scattering intensity at 1660 cm ^-1 .
The measured Raman scattering intensity value is divided by the Raman scattering intensity value at 1660 cm ⁻¹ when the laser output is measured at the maximum using a normal slide glass, and the enhancement factor is calculated to obtain the Raman enhancement effect. Evaluated. When the sensitivity was high, the laser output was lowered, and the rhodamine 6G aqueous solution was diluted with water, and the enhancement magnification was calculated.
The results are shown in Table 6.

The meanings of the symbols in Table 6 are as follows.
◎: Enhancement magnification is 10 ⁶ or more ◎: Enhancement magnification is 10 ⁵ or more and less than 10 ⁶ ○: Enhancement magnification is 10 ⁴ or more and less than 10 ⁵ △: Enhancement magnification is 10 ² or more and less than 10 ³ ×: Enhancement magnification is less than 10 ¹

3. Reproducibility of signal intensity Ten samples for measuring the Raman enhancement effect were prepared, and the coefficient of variation (CV: Coefficient of Variation) measured for each was calculated to evaluate the reproducibility of the Raman enhancement effect. did. The coefficient of variation is defined by the following equation.
The measurement results are shown in Table 6.

  (Coefficient of variation of Raman scattering intensity) = (standard deviation of Raman scattering intensity) / (average of Raman scattering intensity) × 100

  As is apparent from Table 6, the structure of the present invention was found to be excellent in the magnitude and reproducibility of the Raman enhancement effect.

It is typical sectional drawing of the film | membrane surface at the time of giving a sealing treatment process, a surface treatment process, and an electrodeposition process to the anodic oxide film in which the micropore formed by the anodizing process exists. It is typical sectional drawing which shows the surface of the structure of this invention formed by the sealing process by the electrodeposition method. It is typical sectional drawing which shows the surface of the structure of this invention formed by the sealing process by the method using a metal colloid particle. It is typical sectional drawing which shows the surface of the structure of this invention shown by FIG. 2 used as a sample stand for Raman spectroscopic analysis.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Anodic oxide film 2 Micropore 3, 4 Metal 10, 20 Structure 12, 22 Anodized film 14, 24 Micropore 16, 17, 26, 27 Metal 18 Sample

Claims (5)

A structure manufacturing method for manufacturing a structure having at least a part of an aluminum member having an anodized film having micropores on its surface,
Anodizing the surface of the aluminum member to form an anodized film having micropores;
After the anodizing treatment step, a sealing treatment step of filling the micropores with metal,
After the sealing treatment step, a part of the upper surface of the anodized film is removed, and a surface treatment step of setting the average surface roughness (R _a ) of the surface to 30 nm or less,
After the surface treatment step, on the metal filled by the sealing treatment, further by forming metal particles by electrodeposition, to obtain the structure ,
The metal is any one of copper, nickel, chromium, zinc, gold, silver, platinum and palladium;
The method for producing a structure , wherein the metal particles are any of copper particles, nickel particles, chromium particles, zinc particles, gold particles, silver particles, platinum particles, and palladium particles .   The method for producing a structure according to claim 1, wherein the removal of part of the upper surface of the anodized film in the surface treatment step removes 20 to 80% of the thickness of the anodized film.   The method for manufacturing a structure according to claim 1 or 2, wherein the surface treatment step is performed by at least one method selected from the group consisting of mechanical polishing, chemical dissolution, and film removal by an ion beam in a vacuum.   The method for manufacturing a structure according to claim 3, wherein the mechanical polishing is chemical mechanical polishing. A structure obtained by the method for producing a structure according to any one of claims 1 to 4,
The average pore diameter of the micropores present in the anodized film is 10 to 500 nm, the pore diameter variation coefficient is 5 to 20%, and the average particle diameter of the metal particles is larger than the average pore diameter. A structure that is large and smaller than the average center spacing between adjacent micropores.

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