JP2006322067A - Method for producing structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a structure capable of producing a structure having regularly arranged recesses in a reduced time. <P>SOLUTION: Disclosed is a method for producing a structure having: a stripping step in which an aluminum member including an aluminum substrate and an anodized layer present on the surface of the aluminum substrate, which layer contains micropores having an average pore diameter of 10 to 500 nm and a coefficient of variation in pore diameter of less than 30%, is electrolyzed in an aqueous acid solution by using the aluminum member for a cathode to thereby strip the anodized layer off the aluminum substrate so as to produce a structure composed of the anodized layer with a plurality of recesses. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a microstructure and a manufacturing method thereof.

  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 in which the pore diameter variation of micropores is 3% or less. 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 adsorbed 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 the above-described surface plasmon resonance 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 in the pores of a regular anodic oxide film to localize them.
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).

  In the method of producing an anodized film in which micropores are regularly arranged using self-ordering of the anodized film, conventionally, electrolysis is performed for a long time under specific electrolysis conditions, and the generation of micropores is regularly performed. After performing the regularization process, the anodic oxide film obtained in the regularization process is mixed with chromic acid and phosphoric acid in order to expose the vicinity of the bottoms of the most regularly aligned micropores on the surface. It is customary to perform a film removal step of dissolving with an aqueous solution.

  Further, in Patent Document 3, an aluminum member or an alloy thereof is anodized to form a porous layer, and only the porous layer is peeled off from the base material using a reverse electrolysis means. The method of obtaining is described.

JP 2000-31462 A JP 2003-268592 A JP-A-61-88495 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>

However, the film removal process using the mixed aqueous solution of chromic acid and phosphoric acid usually requires a long time of several hours to several tens of hours, although it varies depending on the thickness of the anodized film. Moreover, since the anodic oxide film is dissolved, it cannot be effectively used.
Moreover, under the conditions of the anodizing treatment described in Patent Document 3, the pore diameter variation coefficient was too large, and the obtained anodized film could not be used for a sample table for Raman spectroscopic analysis. Further, when the method of reducing the film thickness by the current recovery method described in Patent Document 3 is used, the regularly arranged dents on the surface of the aluminum member disappear, and the pore diameter variation coefficient is large. Therefore, the aluminum member could not be used for a Raman spectroscopic sample stage or the like.

  Therefore, an object of the present invention is to provide a method for manufacturing a structure capable of obtaining a structure having regularly arranged depressions in a short time, and a structure obtained thereby.

  As a result of intensive studies to obtain a structure having a regular array of depressions in a short time, the present inventor has used an aluminum member having an anodized film having a micropore of a regular array as a cathode in an acid aqueous solution. The present invention was completed by finding that a structure comprising an anodized film having a plurality of regularly arranged depressions can be obtained by separating the anodized film by electrolysis.

That is, the present invention provides the following (1) to (3).
(1) An aluminum member having an aluminum substrate and an anodized film present on the surface of the aluminum substrate and having a micropore with an average pore diameter of 10 to 500 nm and a pore diameter variation coefficient of less than 30% is used as a cathode. A method for producing a structure, comprising a separation step of separating the anodized film and the aluminum substrate by electrolysis in an aqueous solution to obtain a structure composed of an anodized film having a plurality of depressions.
(2) An aluminum member having an aluminum substrate and an anodic oxide film having a micropore having an average pore diameter of 10 to 500 nm and a pore diameter variation coefficient of less than 30%, which is present on the surface of the aluminum substrate, is used as a cathode. A separation step of separating the anodized film and the aluminum substrate by electrolysis in an aqueous solution to obtain an aluminum substrate having a plurality of depressions;
A method of manufacturing a structure comprising: an anodizing treatment step of obtaining an aluminum substrate having an anodized film having micropores on the surface thereof by anodizing the aluminum substrate having the plurality of depressions.
(3) A structure obtained by the method for producing a structure according to (1) or (2).

  According to the structure manufacturing method of the present invention, a structure having regularly arranged depressions can be obtained in a short time.

The present invention is described in detail below.
A first aspect of the present invention is an aluminum member having an aluminum substrate and an anodized film that is present on the surface of the aluminum substrate and has micropores having an average pore diameter of 10 to 500 nm and a pore diameter variation coefficient of less than 30%. A structure comprising a peeling step of separating the anodized film and the aluminum substrate as a cathode to separate the anodized film and the aluminum substrate to obtain a structure composed of an anodized film having a plurality of depressions. It is a manufacturing method.

<Aluminum member>
The aluminum member used in the present invention has an aluminum substrate and an anodized film present on the surface of the aluminum substrate. This aluminum member can be obtained by anodizing the surface of the aluminum substrate.
<Aluminum substrate>
The aluminum substrate is not particularly limited. For example, a commercially available aluminum substrate; a substrate obtained by depositing high-purity aluminum on low-purity aluminum (for example, recycled material); vapor deposition, sputtering, etc. on the surface of silicon wafer, quartz, glass, or the like A substrate coated with high-purity aluminum by the above method; a resin substrate laminated with aluminum.

  Of the aluminum substrate, 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, and 99.80% by mass. The amount is preferably less than 99% by mass, 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 is sufficient, and when it is less than 99.99% by mass, it can be produced at low cost.

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

<Degreasing treatment>
The degreasing treatment is performed for the purpose of dissolving and removing organic components (mainly fat content) and the like attached to the surface using an acid, an alkali, an organic solvent, or the like. 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.
Also, the aluminum substrate is placed in a sodium hydroxide aqueous solution having a pH of 10 to 13 and a temperature of about 30 to 50 ° C., a sulfuric acid aqueous solution having a pH of 1 to 4 and a temperature of about 40 to 70 ° C. It can also be done by soaking.
As a preferred degreasing treatment, there is exemplified a method in which an aluminum substrate is washed with acetone and then immersed in sulfuric acid having a pH of 4 and a temperature of 50 ° C. This method is preferable because fat on the surface of the aluminum is removed while aluminum hardly dissolves.

<Mirror finish processing>
The mirror finish process is performed to eliminate unevenness on the surface of the aluminum substrate and improve the uniformity and reproducibility of the sealing process by an electrodeposition method or the like.
In the present invention, the mirror finish is not particularly limited, and a conventionally known method can be used. For example, a method of polishing with various commercially available polishing cloths, a method of combining various commercially available abrasives (for example, diamond, alumina) and a buff (mechanical polishing), a method of performing electrolytic polishing, and a method of performing chemical polishing. It is done. These methods can be used in appropriate combination.
Methods of electrolytic polishing and chemical polishing are described in, for example, Aluminum Handbook (6th edition), Japan Aluminum Association (2001), p. Various methods described in 164 to 165 may be mentioned.
As a preferable mirror finishing treatment, a method using an abrasive is performed by changing the abrasive used from coarse particles to fine particles over time, and then performing electrolytic polishing. In this case, the final polishing agent is preferably # 1500. According to this method, when the aluminum substrate is manufactured through rolling, the rolling streaks can be eliminated even if rolling streaks are generated during rolling. Further, it is preferable to perform final polishing using a CMP method or a barrier film removing method.
For example, it is preferable to obtain _a surface having an average surface roughness R _{a of} 0.1 μm or less and a glossiness of 60% or more by mirror finishing. 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 determined in accordance with JIS Z8741-1997 "Method 3 60 degree specular gloss" in the direction perpendicular to the rolling direction.

<Anodizing treatment>
As the anodizing treatment, a conventionally known method can be used. Specifically, it is preferable to use the self-ordering method described later.
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 according to the type of the electrolytic solution.

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.
The methods described in these known documents have a technical feature in that a high-purity material is used and a treatment is performed for a long time at a relatively low temperature with a specific voltage corresponding to the electrolytic solution. Specifically, all use materials having an aluminum purity of 99.99% by mass or more, and 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., 40-60 V, 600 minutes (Non-patent Document 7)
0.04 mol / L oxalic acid, 3 ° C., 80 V, film thickness 3 μm (Non-patent Document 8)
0.3 mol / L phosphoric acid, 0 ° C., 195 V, 960 minutes (non-patent document 8)

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

The conditions of the self-ordering anodization treatment cannot be determined unconditionally because they vary depending on the electrolyte used, but generally the electrolyte concentration is 0.01 to 10 mol / L, the solution temperature is 0 to 20 ° C., It is preferable that the current density is 0.1 to 10 A / dm ² , the voltage is 15 to 240 V, the amount of electricity is 3 to 10,000 C / dm ² , and the electrolysis time is 30 to 1000 minutes.
The electrolysis is preferably constant voltage electrolysis.

The properties of the anodized film are as follows.
The thickness including the barrier layer is preferably 0.1 μm or more, and more preferably 1 μm or more. Within the above range, the regularity of the micropores becomes more excellent.
Moreover, it is preferable that thickness is 100 micrometers or less including a barrier layer. When it is in the above range, peeling from the aluminum substrate in the peeling step described later becomes easy.
The thickness of the barrier layer is preferably 600 nm or less, more preferably 5 to 400 nm, and still more preferably 10 to 80 nm. Within the above range, the peelability in the peeling step described later is excellent.

The average pore diameter is 10 to 500 nm, preferably 15 to 100 nm, and more preferably 20 to 80 nm. Within the above range, when the metal is filled into the micropores, the metal is filled more uniformly.
The pore diameter variation coefficient is less than 30%, preferably 5 to 20%. When it is in the above range, a high effect can be obtained when applied to a plasmon resonance device or the like.
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 period of the micropores is preferably 20 to 700 nm, more preferably 23 to 600 nm, still more preferably 25 to 150 nm.
Further, the coefficient of variation of the micropore cycle is preferably less than 30%, more preferably 5% or more and less than 20%. When it is in the above range, a high effect can be obtained when applied to a plasmon resonance device or the like.
The area ratio occupied by the micropores is preferably 10 to 70%.

<Pore wide processing>
The pore-wide treatment is a treatment for expanding the pore diameter of the micropore by dissolving the anodized film by immersing the aluminum substrate in an acid aqueous solution or an alkali aqueous solution after the anodizing treatment. Thereby, it becomes easy to control the regularity of the arrangement of the micropores.

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.

<Barrier layer thinning process>
In the present invention, it is one of preferred embodiments that the above-described aluminum member is an aluminum member obtained by thinning the barrier layer of the anodized film. When the barrier layer is thinned, the peelability in the peeling process described later is excellent.
The present inventor, after anodizing, gradually reduces the voltage without abruptly changing it, that is, does not generate a current recovery period, and maintains the state where the current always flows. It has been found that the barrier layer of the anodized film can be made thin without impairing the regularity of the micropore arrangement of the anodized film by the lowering method. This is probably because no branching occurs because no current recovery period occurs.

Specifically, for example, when the anodizing voltage is 100 V or more, the rate of voltage drop is preferably 20 V / min or less, more preferably 10 V / min or less, and 5 V / min or less. Is more preferable.
The larger the current to be maintained, the better. Specifically, it is preferably at 10 .mu.A / cm ² or more, more preferably 30 .mu.A / cm ² or more, more preferably 50 .mu.A / cm ² or more.
If the current becomes too low, the regularity of the arrangement of micropores will be disturbed. Therefore, when the current drops below 10 μA / cm ² at the above speed, the voltage drop is stopped once and the current is 10 μA / cm ² or more. It is preferable to continue the voltage drop after waiting for the flow.

<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 and a protein that is denatured or decomposed with an acid is targeted, the acid remaining on the aluminum surface is neutralized, which is used for anodizing treatment. Therefore, neutralization treatment may be performed. The neutralization treatment can be performed by a conventionally known method.

<Peeling process>
The peeling step is a step of obtaining a structure comprising an anodized film having a plurality of depressions by separating the anodized film and the aluminum substrate by electrolysis in an acid aqueous solution using the above-described aluminum member as a cathode. It is. In the stripping step, electrolysis is performed using the aluminum member as a cathode. This is referred to as “reverse electrolysis” because the anodizing electrolysis is the reverse of using the aluminum member as the anode.

  In the peeling process, hydrogen is generated at the interface between the anodized film of the aluminum member and the aluminum substrate due to this reverse electrolysis, and the barrier layer at the interface between the anodized film and the aluminum substrate is reduced by this hydrogen, and the aluminum ions are reduced. Thus, the anodic oxide film and the aluminum substrate are considered to be separated at the interface.

In reverse electrolysis, the above-described aluminum member is used as a cathode, and electricity is supplied from the aluminum substrate side.
The anode is not particularly limited, and examples thereof include a Pt-plated Ti electrode, a Pt electrode, and a carbon electrode.

The acid aqueous solution used for reverse electrolysis preferably has a pH of 1 to 7, more preferably a pH of 2 to 6, and even more preferably a pH of 2.5 to 5.5. Moreover, it is preferable that it is 0.01-100 mS / cm, and, as for the electrical conductivity of acid aqueous solution, it is more preferable that it is 0.1-50 mS / cm.
When the pH and electrical conductivity of the acid aqueous solution are within the above ranges, corrosion and residual film of the aluminum substrate are difficult to occur, and the peelability is improved.
If the electric conductivity of the acid aqueous solution is too low, a minimum current value may not be generated. In that case, it is preferable to increase the ion concentration in the acid aqueous solution to generate a minimum current value. On the contrary, if the ion concentration in the acid aqueous solution is too high, a minimum value of the current value is generated, but it is completed in a short time, and then the current value rapidly increases, so that control becomes difficult. Furthermore, if the time to reach the minimum value is exceeded, corrosion will occur.

In the acid aqueous solution, for example, oxalic acid, sulfuric acid, and phosphoric acid can be suitably used as the acid.
Further, for example, a metal salt compound that shows acidity when dissolved in water, or an organic compound that shows acidity when dissolved in water can be used.
Examples of the metal salt compound that dissolves in water and exhibits acidity include aluminum oxalate, aluminum sulfate, aluminum lactate, aluminum fluoride, and aluminum borate.
The organic compound that is acidic when dissolved in water is preferably a carboxylic acid. For example, saturated aliphatic dicarboxylic acids such as adipic acid, unsaturated aliphatic dicarboxylic acids such as maleic acid, aromatic monocarboxylic acids such as benzoic acid, aromatic dicarboxylic acids such as phthalic acid, and aromatic oxycarboxylic acids such as salicylic acid Are preferable.
In addition, a salt that is neutral when dissolved in water, that is, a neutral salt, can also be used. Suitable examples of the neutral salt include carbonates such as ammonium carbonate and borates such as ammonium borate.
In the case where a neutral salt is used, it is also a preferred embodiment to use a mixed bath to which a fluoride, a carbonic acid derivative or an acid amide is added as an additive. Examples of the fluoride include ammonium fluoride. Examples of the carbonic acid derivative include guanidine carbonate, urea, and formaldehyde. Examples of the acid amide include acetamide.
Among these, oxalic acid, aluminum oxalate, sulfuric acid, aluminum sulfate or a mixture thereof is preferable. In particular, aluminum sulfate and sulfuric acid are preferable in terms of availability and waste liquid treatment.

  Moreover, it is one of the preferable aspects to use the same kind as the electrolyte solution used by the said anodizing process. Thereby, it becomes possible to perform anodizing treatment and reverse electrolysis in the same electrolytic cell. Moreover, even if it is a case where it carries out by another electrolytic cell, there is no bad influence by carrying in of the liquid to a reverse electrolytic cell.

The reverse electrolysis conditions vary depending on the electrolyte used, and therefore cannot be determined unconditionally.
For example, the concentration of the electrolytic solution is preferably 0.4 to 10% in the case of an oxalic acid aqueous solution, 2 to 20% in the case of an aqueous sulfuric acid solution, and 0.4 to 5% in the case of an aqueous phosphoric acid solution.
In general, the temperature of the electrolytic solution is preferably 0 to 50 ° C, and more preferably 10 to 35 ° C.
Current density is preferably 0.1~200A / dm ^2, more preferably from 0.3~50A / dm ^2, and even more preferably 0.5~10A / dm ^2. When it is within the above range, unevenness does not occur in peeling, and it can be performed more uniformly.
The voltage is preferably 5 to 500V, and more preferably 10 to 240V. When reverse electrolysis is performed subsequent to the anodizing treatment, it is preferable to perform constant voltage reverse electrolysis at the same voltage as the anodizing treatment.
Also, 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. In the method of changing the voltage intermittently, it is one of preferred embodiments that the voltage is lowered sequentially.
The electrolysis time is preferably 1 to 500 seconds, and more preferably 10 to 120 seconds.

  The above range is preferable because it is more excellent in the peelability between the barrier layer of the anodized film and the aluminum substrate, and the regularity of the depressions in the anodized film becomes higher. If the amount of electricity is too large or the electrolysis time is too long, the interface between the barrier layer of the anodized film and the aluminum substrate becomes high temperature, the resulting structure may be deformed, and the regularity of the dents may be impaired.

  The reverse electrolysis is preferably stopped when the current value is monitored and the current value is in the range from the minimum value to the value obtained by adding 30% to the minimum value. Or, it is more preferable to stop and end at the time of the vicinity. In this case, the peelability and the surface properties of the anodized film and the aluminum substrate after peeling are excellent.

In the aluminum substrate obtained by performing the peeling step, a residue of an anodic oxide film having a thickness of 0.2 μm or less may remain in a region of 10% or less of the peeling surface. When this aluminum substrate is used, it is preferable that no anodized film remains.
Therefore, in this case, it is preferable to perform chemical treatment after reverse electrolysis to remove the residue of the anodized film. Specifically, it can be removed by bringing various acidic or alkaline aqueous solutions into contact with the anodized film.

Examples of the acidic aqueous solution include a phosphoric acid aqueous solution, a sulfuric acid aqueous solution, a nitric acid aqueous solution, an oxalic acid aqueous solution, and a mixed aqueous solution of chromic acid and phosphoric acid. Among these, a mixed aqueous solution of chromic acid and phosphoric acid is preferable.
The acidic aqueous solution preferably has a pH of -0.3 to 6, more preferably a pH of 0 to 4, and still more preferably a pH of 2 to 4.
It is preferable that the temperature of acidic aqueous solution is 20-60 degreeC, and it is more preferable that it is 30-50 degreeC.
The treatment time is preferably 1 second to 6 hours, more preferably 5 seconds to 3 hours, and even more preferably 10 seconds to 1 hour.

Examples of the alkaline aqueous solution include aqueous solutions of sodium hydroxide, sodium carbonate, and potassium hydroxide.
The alkaline aqueous solution preferably has a pH of 10 to 13.5, more preferably a pH of 11 to 13.
The temperature of the alkaline aqueous solution is preferably 10 to 50 ° C, and more preferably 20 to 40 ° C.
The treatment time is preferably 1 second to 10 minutes, more preferably 2 seconds to 1 minute, and even more preferably 3 seconds to 30 seconds.

Further, when a part of the anodic oxide film remains even after the peeling process, the remaining anodic oxide film can be completely removed by repeating the anodic oxidation treatment and the peeling process a plurality of times alternately. .
When the anodized film is peeled off by this method, current recovery is not performed, and the regularity of the arrangement of the depressions on the aluminum substrate side is not disturbed. Therefore, this method is suitable in the second aspect of the present invention described later. .

Examples of suitable conditions for reverse electrolysis are illustrated below.
<Preferred condition 1>
Cathode: Anodized film obtained by anodizing with an oxalic acid aqueous solution having a concentration of 0.3 mol / L and a temperature of 17 ° C. under conditions of a voltage of 40 V and a treatment time of 60 minutes, a thickness of 60 μm, a pore diameter of 35 nm, and a pore diameter Fluctuation coefficient 15%, micropore period 63nm
Anode: Carbon electrode Electrolyte: Concentration 0.04 g / L (in terms of aluminum ion), pH 3.8, electric conductivity 0.6 mS / cm, temperature 33 ° C. Aluminum sulfate aqueous solution Voltage: 40 V (set voltage)
Current density: 5 A / dm ² (minimum value 1 A / dm ² )
Processing time: 40 seconds (minimum)

In the first aspect of the present invention, the treatment time of the peeling step is extremely short compared to the time required for the film removal step of dissolving with a conventional mixed aqueous solution of chromic acid and phosphoric acid. Therefore, according to the first aspect of the present invention, an efficient structure can be manufactured.
Furthermore, the mixed aqueous solution of chromic acid and phosphoric acid has a rapid deterioration of the dissolving ability when the aluminum oxide content exceeds 15 g / L as Al ₂ O ₃ during the film removal step. It needs to be replaced. Since the anodic oxide film having a small coefficient of variation in pore diameter used in the present invention is generally thick, the amount of aluminum oxide eluted in a single treatment is large and the treatment liquid is severely deteriorated.
On the other hand, in the present invention, since the anodized film is peeled off in a solid state at the interface with the aluminum substrate, it can be easily separated with a filter or the like, and the acid aqueous solution used for reverse electrolysis does not deteriorate.
Therefore, the treatment time of the peeling step and the consumption amount of the acid aqueous solution in the present invention are much shorter than the treatment time of the film removal step and the consumption amount of the treatment solution by the conventional mixed aqueous solution of chromic acid and phosphoric acid, Few.

In the peeling step, the barrier layer is dissolved by the reverse electrolysis described above, and a structure made of an anodized film having a plurality of depressions is obtained.
On the other hand, the aluminum substrate from which the anodized film has been peeled becomes an aluminum substrate having a plurality of depressions. The aluminum substrate having the plurality of depressions is used in a second aspect of the present invention described later. Hereinafter, it demonstrates concretely using drawing.

FIG. 1 is an explanatory view of a method for producing a structure according to the present invention.
FIG. 1A is a schematic cross-sectional view of an aluminum member before the peeling step. As shown in FIG. 1A, the aluminum member 10 has an aluminum substrate 12 and an anodized film 14 present on the surface of the aluminum substrate 12. In the anodic oxide film 14, micropores 16 are present, and a lower part thereof is a barrier layer 18.
FIG. 1B and FIG. 1C are schematic cross-sectional views of the structure and the aluminum substrate obtained by the peeling step, respectively.
A structure 20 shown in FIG. 1B is obtained by dissolving the barrier layer 18 of the anodized film 14 of the aluminum member 10 shown in FIG. 1A, and is formed from an anodized film having a plurality of depressions 22. Become.
An aluminum substrate 24 shown in FIG. 1C is obtained by dissolving the barrier layer 18 of the anodized film 14 of the aluminum member 10 shown in FIG. 1A and has a plurality of depressions 26.

  A second aspect of the present invention is an aluminum member having an aluminum substrate and an anodized film that is present on the surface of the aluminum substrate and has micropores having an average pore diameter of 10 to 500 nm and a pore diameter variation coefficient of less than 30%. By separating the anodized film and the aluminum substrate by electrolysis in an acid aqueous solution as a cathode to obtain an aluminum substrate having a plurality of depressions, and an aluminum substrate having the plurality of depressions. And a anodizing treatment step of obtaining a structure made of an aluminum substrate having an anodized film having micropores on the surface thereof.

  The peeling step of the second aspect of the present invention is performed in the same manner as the peeling step of the first aspect of the present invention.

<Anodizing process>
In the second aspect of the present invention, an anodizing treatment step is performed after the peeling step.
The anodizing treatment step is a step of obtaining an aluminum substrate having an anodized film having micropores on the surface thereof by anodizing the aluminum substrate having a plurality of depressions obtained in the peeling step.

  In the aluminum substrate having a plurality of depressions obtained in the peeling step, the shape of the bottom part of the barrier layer of the micropores that are most regularly aligned is a depression on the surface (see FIG. 1C). ). Therefore, the depressions on the surface are almost hemispherical and are regularly aligned like micropores.

A conventionally well-known method can be used for an anodizing process process. Specifically, it is the same as the anodizing treatment for obtaining the aluminum member described above.
Here, it is one of the preferable embodiments to use the same type of electrolyte as that used in the reverse electrolysis. Thereby, it becomes possible to perform reverse electrolysis and an anodizing process in the same electrolytic cell. Moreover, even if it is a case where it carries out by another electrolytic cell, there is no bad influence by carrying in of the liquid to an anodizing treatment tank.

In this anodizing treatment step, a plurality of regularly arranged depressions on the surface of the aluminum substrate are used as starting points for the anodizing treatment to form an anodized film having regularly arranged micropores.
Therefore, a structure comprising an aluminum substrate having an anodized film having regularly arranged micropores on the surface is obtained by the anodizing treatment step.

  FIG. 1D is a schematic cross-sectional view of a structure obtained by an anodizing process. The structure 28 shown in FIG. 1D is obtained by forming the anodized film 30 by subjecting the aluminum substrate 24 shown in FIG. At the time of anodizing, micropores 32 are formed starting from the depression 26 of the aluminum substrate 24. Therefore, the structure 28 is made of the aluminum substrate 34 having the anodic oxide film 30 having the micropores 32 on the surface.

  In the second aspect of the present invention, the treatment time of the peeling step is extremely short compared to the time required for the conventional film removal step of dissolving with a mixed aqueous solution of chromic acid and phosphoric acid. Therefore, according to the 2nd aspect of this invention, manufacture of an efficient structure is attained.

<Structure>
A structure comprising an anodized film having a plurality of depressions obtained by the first aspect of the present invention and a structure comprising an aluminum substrate having on its surface an anodized film having a micropore obtained by the second aspect of the present invention Since each has a plurality of depressions or micropores having a regular arrangement, it can be applied to various applications.
For example, it can be used as a sample table for Raman spectroscopic analysis by filling a plurality of depressions or micropores with metal by a sealing treatment.
It can also be used as a nanoprint mold.

<Sealing treatment>
The metal used for the sealing treatment is an element composed of a metal bond having free electrons, and is not particularly limited, but is preferably a metal in which plasmon resonance has been confirmed. Among these, gold, silver, copper, nickel, and platinum are known to easily cause plasmon resonance (Hyundai Kagaku, September 2003, p. 20 to 27 (non-patent document 9)), and are preferable. In particular, gold and silver are preferable because electrodeposition and colloidal particle preparation are easy.

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 in which a dispersion of colloidal metal particles is applied to the structure of the present invention and dried is preferably mentioned. The metal is preferably a single particle or an aggregate.
As the electrodeposition method, a conventionally known method can be used. Specifically, for example, in the case of gold electrodeposition, an aluminum member is immersed in a dispersion at 30 ° C. containing 1 g / L HAuCl ₄ and 7 g / L H ₂ SO _4, and a constant voltage of 11 V ( (Adjusted with slidac), and a method of electrodeposition treatment for 5 to 6 minutes.
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 10), and this method can also be used.

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 in which an aqueous solution of a metal salt is reduced.
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, a solvent that can be mixed with water, for example, alcohol such as ethyl alcohol, n-propyl alcohol, i-propyl alcohol, 1-butyl alcohol, 2-butyl alcohol, t-butyl alcohol, methyl cellosolve, butyl cellosolve, and water These mixed solvents 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. Thereby, only the particles filled in the plurality of depressions or micropores remain, and the particles not filled in the plurality of depressions or micropores are removed.

It is preferable that the adhesion amount of the metal after the sealing treatment is 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 plurality of dents or micropore openings that are not sealed to the area of the structure 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.

In the structure after the sealing treatment, the metal seals the plurality of depressions or micropores, and is present as particles on the surface of the structure.
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. In addition, depending on the molecular weight of the substance used as the specimen for Raman spectroscopic analysis and the viscosity of the liquid, there may be a problem that it does not enter between 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, and the problem that the substance to be detected does not enter between the metal particles is reduced.
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.
Since the structure after the sealing treatment can generate localized plasmon resonance having a higher intensity than that of the prior art, a stronger Raman enhancement effect can be obtained when used for Raman spectroscopic analysis. Therefore, the sample stand for Raman spectroscopic analysis using the structure after the sealing treatment is useful.
The method for using the sample stage for Raman spectroscopic analysis using the structure after the sealing treatment is the same as the method for using the conventional sample stage for Raman spectroscopic analysis. Specifically, the sample stage for Raman spectroscopic analysis using the structure after sealing treatment is irradiated with light, and the Raman scattering intensity of the reflected light or transmitted light is measured. Detect the properties of the material in the vicinity of the retained metal.

<Nanoprint>
The structure of the present invention can be used as a nanoprint mold. Specifically, a substrate having a plurality of protrusions can be obtained by pouring a resin or the like into a plurality of depressions or micropores of the structure of the present invention and hardening. The substrate having the plurality of protrusions can be used for an optical device, for example.

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these.
1. Fabrication of structures (Examples 1 to 10)
The substrate was successively subjected to a mirror finish treatment, self-ordering anodizing treatment and reverse electrolysis to obtain a structure made of an anodized film and an aluminum substrate. The obtained aluminum substrate was sequentially subjected to the main anodizing treatment, pore widening treatment, sealing treatment, surface treatment and electrodeposition treatment to obtain a structure comprising an aluminum substrate in which micropores were sealed with metal.
Details of each process will be described below.

(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 finish treatment The following mirror finish treatment was performed on the substrate.
<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 disk (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).
Electropolishing was performed for 2 minutes at a constant current of 130 mA / cm 2 using an electrolytic solution (temperature: 70 ° C.) having the following composition, using the anode as a substrate and the cathode as a carbon electrode. 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) Self-ordered anodizing treatment (formation of dents)
The surface of the mirror-finished substrate was subjected to self-ordering anodizing treatment as follows to form depressions. This depression became a starting point for forming micropores in the anodizing process described later.

<Self-ordered anodizing treatment>
A sulfuric acid aqueous solution having a concentration of 0.3 mol / L and a temperature of 16 ° C. was prepared using sulfuric acid (a reagent manufactured by Kanto Chemical Co., Inc.). The substrate is immersed in this sulfuric acid aqueous solution, self-ordered anodizing treatment is performed for 7 hours under the conditions of a voltage of 25 V and a current density of 0.8 A / dm ² (when stable), and an anodized film having a film thickness of 90 μm is formed on the substrate. 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. A PET tape (Damplon tape, manufactured by Nitto Denko) was previously applied to the surface of the substrate not facing the electrode surface so as not to be anodized.

<Thickness measurement method>
The substrate on which the anodized film is formed is bent, and the side surface (fracture surface) of the cracked portion is used with an ultra-high resolution SEM (Hitachi S-900, manufactured by Hitachi, Ltd.) at an acceleration voltage of 20 V and a magnification of 200. The film thickness was measured. Ten locations were randomly extracted at one time, and the average value was obtained as the film thickness. The film thickness values at 10 locations were all within a range of ± 10% of the average value.

(4) Reverse electrolysis Using the acid aqueous solutions A1 to A5 and B1 to B3 having the properties shown in Table 1, reverse electrolysis is performed on the substrate on which the anodized film is formed under the conditions shown in Table 2, and anodization is performed. The film and the aluminum substrate were peeled off. The acid aqueous solutions A1 to A5 were prepared by adding aluminum sulfate in addition to sulfuric acid so that the aluminum concentration was 0.2 g / L. Reverse electrolysis was terminated immediately after the current value was monitored with an ammeter and reached a minimum value.

(5) Chemical treatment In Examples 5 and 7, the peeled aluminum substrate was further subjected to chemical treatment. The chemical treatment was performed by immersing the aluminum substrate in a mixed aqueous solution of chromic acid and phosphoric acid (composition: 30 g of chromic anhydride, 100 g of 85 mass% phosphoric acid, 1500 g of water; temperature 50 ° C.) for 5 minutes.

(6) Main anodizing treatment In Examples 1 and 8, the main anodizing treatment was performed on the aluminum substrate obtained by peeling off the anodized film by reverse electrolysis. In this anodizing treatment, an aluminum substrate is immersed in the same sulfuric acid aqueous solution (concentration 0.3 mol / L, temperature 16 ° C.) used in the self-ordering anodizing treatment, and the voltage is 25 V and the current density is 0.8 A / dm. ² (Stable) The test was performed for 60 seconds to form an anodic oxide film having a thickness of 100 nm on the substrate.

(7) Pore-wide treatment The aluminum substrate after this anodizing treatment was subjected to a pore-wide treatment in order to improve the uniformity of the sealing treatment described later. The pore-wide treatment was performed by immersing the aluminum substrate in a phosphoric acid aqueous solution (temperature 30 ° C.) having a concentration of 50 g / L. The immersion time was 20 minutes for the aluminum substrate obtained in Example 1 and 6 minutes for the aluminum substrate obtained in Example 8.

(8) Sealing treatment The aluminum substrate after the pore wide treatment was subjected to sealing treatment as follows. That is, an aqueous solution (temperature 30 ° C.) having a HAuCl ₄ .4H ₂ O concentration of 1 g / L and an H ₂ SO ₄ concentration of 7 g / L is used as a plating solution, a high-purity platinum plate is used as a counter electrode, and a 11 V AC using a slidac. Then, sealing treatment was performed by performing electrodeposition treatment for 5 minutes.

(Comparative Example 1)
In Example 1, instead of the reverse electrolysis, an aluminum substrate was placed in a mixed aqueous solution of chromic acid and phosphoric acid (composition: chromic anhydride 30 g, 85% by mass phosphoric acid 100 g, water 1500 g; temperature 50 ° C.) for 12 hours. The film was removed by immersion.
As a result, the anodized film was dissolved and an aluminum substrate was obtained. Therefore, an anodized film as a structure was not obtained.

(Comparative Example 2)
The film removal treatment was performed in the same manner as in Comparative Example 1 except that the immersion time in the mixed aqueous solution of chromic acid and phosphoric acid was 480 seconds.
As a result, an aluminum substrate was obtained, but the residue of the anodic oxide film adhered to the entire surface of the aluminum substrate. Therefore, an anodized film as a structure was not obtained.

2. Evaluation of peeled state The peeled state between the anodized film after reverse electrolysis and the aluminum substrate in each of the above examples was evaluated. Specifically, the peeled surface of the aluminum substrate after reverse electrolysis was visually observed to evaluate the presence or absence of residual film (residue of the anodized film) and the presence or absence of corrosion. For Examples 5 and 7, the aluminum substrate after the chemical treatment was evaluated.
The results are shown in Table 3. In the table, “remaining film on the peeling surface of the aluminum substrate” means that the area of the part where the remaining film is present is 0% or more and less than 3%; It was. In the table, “corrosion of peeling surface of aluminum substrate” indicates that the area of the portion where corrosion exists is 0% or more and less than 3%; It was.
As is apparent from Table 3, the method for producing the structure of the present invention had little residual film on the peeling surface of the obtained aluminum substrate. Even when there was some remaining film (Examples 4 and 6), the remaining film could be reduced by performing chemical treatment after reverse electrolysis (Examples 5 and 7).

3. Evaluation of a structure comprising an anodized film In Examples 1 and 8, a phosphoric acid aqueous solution (temperature: 25 ° C.) having a concentration of 50 g / L was applied to the peeled surface of the anodized film obtained by the reverse electrolysis. It was dripped enough to get wet. After 20 minutes from the dropping, it was washed with water and dried. The film thickness of the anodized film was 70 μm.
Subsequently, the peeling surface of the anodic oxide film was observed by SEM. As a result, a part of the anodic oxide film including the barrier layer was dissolved and removed by the phosphoric acid aqueous solution, and the micropores were exposed on the peeling surface. That is, the bottom of the micropore was dissolved, and the micropore was in a state of penetrating both surfaces of the anodized film.
The peeling surface where the micropores were exposed was photographed at an acceleration voltage of 12 V and a magnification of 100,000 times using an FE-SEM (S-900, manufactured by Hitachi, Ltd.). The obtained SEM photograph was read with a scanner and binarized using an image processing software (Image Factory, manufactured by Asahi High-Tech). Furthermore, by approximating the shape of the micropore to an equivalent circle, the average pore diameter and the standard deviation of the pore diameter are calculated from the distribution of the diameters, and the pore diameter standard deviation is divided by the average pore diameter to obtain the pore diameter variation coefficient. Asked. Further, the average center interval (pore period) between the micropores was measured for 100 pores and calculated from the average value.
As a result, the structure composed of the anodized film had an average pore diameter of 30 nm in both Examples 1 and 8, a pore diameter variation coefficient of 3% in both Examples 1 and 8, and a pore period of Example 1 and 8. All of 8 were 63 nm.

4). Evaluation of Structures Consisting of Aluminum Substrate (1) Properties of Structures For the aluminum substrates after the pore-wide treatment in Examples 1 and 8 and the aluminum substrates obtained in Comparative Examples 1 and 2, the average was obtained by the same method as described above. The pore diameter, the coefficient of variation of the pore diameter, and the pore period were determined.
As a result, the structure composed of the aluminum substrate after the pore-wide treatment had an average pore diameter of 30 nm in both Examples 1 and 8, a pore diameter variation coefficient of 3% in both Examples 1 and 8, and a pore period. Both Examples 1 and 8 were 63 nm. On the other hand, the structure made of the aluminum substrate obtained in Comparative Example 1 had an average pore diameter of 30 nm, a pore diameter variation coefficient of 3%, and a pore period of 63 nm. The structure made of the aluminum substrate obtained in Comparative Example 2 had an average pore diameter of 40 nm, a pore diameter variation coefficient of 15%, and a pore period of 63 nm.

(2) Raman enhancement effect 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) were used in Example 1. And 8 on the surface of the structure comprising the aluminum substrate after the sealing treatment, using a Raman spectroscopic analyzer (T64000, manufactured by HORIBA, Ltd.), an excitation wavelength of 488 nm, a Raman shift measurement range of 1800 to 800 cm ^−1. Under these conditions, the Raman scattering intensity at 1660 cm ⁻¹ was measured.
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.
As a result, the structure made of the aluminum substrate after the sealing treatment had a Raman enhancement effect enhancement factor of 10 ⁴ or more in both Examples 1 and 8.

It is explanatory drawing of the manufacturing method of the structure of this invention.

Explanation of symbols

10 Aluminum member 12, 24, 34 Aluminum substrate 14, 30 Anodized film 16, 32 Micropore 18 Barrier layer 20, 28 Structure 22, 26 Dimple

Claims (3)

  An aluminum member having an aluminum substrate and an anodized film present on the surface of the aluminum substrate and having an average pore diameter of 10 to 500 nm and a micropore having a pore diameter variation coefficient of less than 30% is used as a cathode in an acid aqueous solution. A method for producing a structure comprising a peeling step of separating the anodized film and the aluminum substrate by electrolysis to obtain a structure composed of an anodized film having a plurality of depressions. An aluminum member having an aluminum substrate and an anodized film present on the surface of the aluminum substrate and having an average pore diameter of 10 to 500 nm and a micropore having a pore diameter variation coefficient of less than 30% is used as a cathode in an acid aqueous solution. A peeling step of separating the anodized film and the aluminum substrate by electrolysis to obtain an aluminum substrate having a plurality of depressions;
A method of manufacturing a structure comprising: an anodizing treatment step of obtaining an aluminum substrate having an anodized film having micropores on the surface thereof by anodizing the aluminum substrate having the plurality of depressions.   A structure obtained by the method for producing a structure according to claim 1.

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