JP2009127080A - Method for manufacturing fine structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a fine structure having a metallic body having a uniform head part diameter by plating treatment while avoiding the effect of the variation of metal filling state in fine pores. <P>SOLUTION: The method of manufacturing the fine structure 1 provided with a dielectric base material 2 having a plurality of fine pores 4 and the metallic body 9 which has a part filled in each fine pore 4 and a head part 9a projecting from each fine pore 4 and is sized enough to generate localized plasmon, includes: a step (A) of preparing the dielectric base material 2 having a plurality of the bottomed 4b fine pores 4 on the surface 2a; a step (B) of filling a metal 5 in the fine pores 4; a step (C) of depositing a metal 7 to become an electrode on the surface 2a of the dielectric base material 2; a step (D) of removing the dielectric base material 2 from the back surface 2b side of the dielectric base material 2 until the metal 5 filled in the bottomed 4b fine pores 4 is exposed; and a step (E) of forming a head part 9a having a diameter 9b larger than the pore diameter 4c of the fine pores 4 on the exposed part 5a by plating. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention has a dielectric substrate having a plurality of micropores, a portion filled in each of the micropores, and a head protruding from each of the micropores, and having a size capable of generating localized plasmons. The present invention relates to a method for manufacturing a microstructure including a metal body.

  When light is irradiated while the sample is in contact with a microstructure in which metal bodies having nano-order irregularities are distributed, the electric field is enhanced by localized plasmon resonance, and light emitted from the sample in contact with the microstructure is generated. It is known to be enhanced.

  Sensor devices and Raman spectroscopic devices using this localized plasmon resonance phenomenon are also known. Raman spectroscopy is a method for obtaining a spectrum (Raman spectrum) of Raman scattered light obtained by dispersing scattered light generated by irradiating a sample with single wavelength light.

  Localized plasmon resonance means that when light is incident on a microstructure in which metal bodies with nano-order irregularities are distributed, the free electrons resonate with the electric field of the light and vibrate. It is a phenomenon that generates a strong electric field in the periphery, and it is known that a higher electric field enhancing effect is exhibited when the convex portions of the metal body are close to each other.

In Patent Document 1, as a fine structure having a dielectric base material and a metal body, an anodized base material is anodized to form a dielectric base material having micropores on the surface. A structure (mushroom structure) having a portion filled with a metal body and a head protruding from each fine hole by filling the inside with metal by plating is disclosed. In this structure, the electric field enhancement effect by the localized plasmon is obtained by bringing the heads of adjacent metal bodies close to each other.
JP 2005-172569 A

  In recent years, a fine structure having an electric field enhancement effect due to localized plasmons by bringing the head of the metal body close to each other has been desired to have a uniform electric field enhancement effect on the distribution and arrangement surface of the metal body. The head diameter of each metal body is required to be uniform.

Here, in order to make the head diameter of each metal body uniform, variation in the filling state of the metal in the fine holes in the plating process is reduced, and the heads of the respective metal bodies are formed substantially simultaneously in the plating process. There is a need.

  However, since there is an anodized portion called a barrier layer at the bottom of the fine holes of the dielectric substrate obtained by anodizing the substrate to be anodized, each fine hole is plated in the fine holes. There is a possibility that a difference in the deposition potential occurs in the metal, and the filling state of the metal in each fine hole may vary. Thereby, it is difficult to form the heads protruding from the respective micro holes substantially simultaneously. Therefore, the surface of the fine structure is in a state in which the heads of the metal bodies are not formed at the same time, so that the heads with non-uniform diameters are arranged, that is, in the state where plating unevenness occurs.

  With the technique disclosed in Patent Document 1, it is not possible to reduce the variation in the metal charge state in each fine hole in the plating process due to the presence of the barrier layer.

  In view of the above circumstances, an object of the present invention is to provide a method for manufacturing a microstructure including a metal body having a uniform head diameter, avoiding the influence of variations in the metal filling state due to the plating process in each microhole. It is to provide.

  In order to solve the above problems, a manufacturing method of a microstructure of the present invention includes a dielectric base material having a plurality of micro holes, a portion filled in each micro hole, and a head protruding from each micro hole. And a method of manufacturing a microstructure having a metal body having a size capable of generating localized plasmons, the step of preparing a dielectric substrate having a plurality of bottomed micropores on the surface (A ), A step (B) of filling the metal in the micropores, a step (C) of depositing a metal that can serve as an electrode on the surface of the dielectric substrate, and a bottomed surface from the back side of the dielectric substrate. A step (D) of removing the dielectric substrate until the metal filled in the micropores is exposed, and a step of forming a head having a diameter larger than the pore diameter of the micropores by plating on the exposed portions. (E).

  Here, the above-mentioned “dielectric substrate having a plurality of bottomed micropores on the surface” means a dielectric substrate having a surface having a plurality of bottomed micropores, It does not mean a dielectric substrate having a plurality of bottomed micropores on the surface. The above “on the surface of the dielectric substrate” does not mean only the surface of the dielectric substrate, but also includes the inside of the micropores. The above “from the back side of the dielectric base material” means not only the back side of the dielectric base material but also the presence of an anodized metal body on the back side of the dielectric base material. This means from the side of the metal body to be anodized. The above "exposure" means that the bottom of the micropore is removed by removing the dielectric base from the back side of the dielectric base, and the metal filled in the microhole is exposed from the surface. Means. In addition, it does not mean that the metal filled in the micropores is completely exposed, but means that the metal filled in the micropores is partially exposed. The above “exposed part” means an exposed metal part. The “pore diameter of the micropore” means the diameter of the micropore surface.

  In this step (A), an anodized substrate having a plurality of bottomed micropores formed on the anodized metal body by anodizing the anodized metal body as a dielectric substrate. Can be used.

  In this step (E), it is desirable to continue the plating process on the exposed portion until the gap between the heads of the metal body is 10 nm or less. Here, the “gap between the heads” refers to a gap between the parts where the maximum diameters of the heads are closest.

  In this step (B), an insulator layer can be formed on the filled metal.

  In this step (B), two or more kinds of metals having different materials can be prepared and sequentially filled with the metals.

  According to the manufacturing method of the present invention, the bottom of each fine hole is removed by removing from the back side of the dielectric base material filled with metal in the fine hole, and the filled metal in each fine hole is removed. It is exposed substantially uniformly from the back side of the dielectric substrate. By forming the metal heads by plating the substantially uniformly exposed metal parts, the heads of the metal bodies are formed substantially simultaneously. Therefore, it is possible to manufacture a fine structure having a metal body with a uniform head diameter by plating without being affected by variations in metal filling in the fine holes.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a first embodiment of the present invention. FIG. 1A shows a process for preparing a dielectric substrate 2 by anodizing a metal body 3 to be anodized, FIG. 1B anodizing the metal body 3 to be anodized, and FIG. FIG. 1D shows a step of depositing a metal 7 that can be an electrode, and FIG. 1E shows a back surface 2 b of the dielectric substrate 2. From the side, the process of removing the dielectric substrate 2 until the metal 5 filled in each microhole 4 is exposed, FIG. 1 (f) shows a diameter 9 b larger than the hole diameter 4 c of the microhole 4 by plating. The process of forming the head 9a which has is shown.

The anodized metal body 3 and the dielectric substrate 2 will be described. In the present embodiment, a metal oxide body obtained by anodizing a part of the anodized metal body 3 is prepared as the dielectric substrate 2. Specifically, the anodized metal body 3 can be anodized. There is no limitation as long as it is aluminum (Al), titanium (Ti), tantalum (Ta), hafnium (Hf), silicon (Si), indium (In), zinc (Zn), or an alloy of two or more of these. Aluminum (Al) is desirable. When aluminum (Al) is used as the anodized metal body 3 and a part thereof is anodized, an alumina layer (Al ₂ O ₃ ) having a plurality of bottomed 4 b fine holes 4 is used as the dielectric substrate 2. Prepared.

  Here, anodic oxidation means that the anodized metal body 3 is used as an anode, carbon, aluminum or the like is used as a cathode (counter electrode), and these are immersed in an anodic oxidation electrolyte, and a voltage is applied between the anode and the cathode. By doing so, a metal oxide body is formed on the anodized metal body 3. Although there is no particular limitation on the electrolytic solution, it is desirable that the acidic electrolytic solution contains one or more acids such as sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, and amidosulfonic acid. Is good.

  As shown in FIG. 1B, when the anodized metal body 3 is anodized, an oxidation reaction proceeds in a substantially vertical direction from the anodized surface, and the dielectric substrate 2 is generated. In the surface 2a of the dielectric substrate 2, the fine holes 4 are regularly opened 4a, and each fine hole 4 has a rounded bottom 4b. As specific anodizing conditions, when aluminum is used to form an alumina layer, oxalic acid is used as an electrolyte, an electrolyte concentration of 0.5 M, a liquid temperature of 15 ° C., and an applied voltage of 40 V are given as an example. It is done. By controlling the electrolysis time, an alumina layer having a predetermined layer thickness can be generated. The generated alumina layer has a large number of fine holes 4 having openings 4a. Usually, the pitch of adjacent fine holes 4 is in the range of 10 to 500 nm, and the hole diameter 4c of each fine hole 4 is: It is in the range of 5 to 400 nm. A method for controlling the hole diameter 4c of the microholes 4 is disclosed in Japanese Patent Application Laid-Open Nos. 2001-9800 and 2001-138300. Is possible.

  Here, the dielectric base material 2 used for carrying out the present invention is not limited to the dielectric base material 2 described above. For example, the dielectric base material 2 such as a resin may be prepared by performing a fine processing technique, lithography, and etching for forming a plurality of concave portions regularly arranged by a nanoprint technique.

  Next, the process of filling the fine holes 4 of the dielectric substrate 2 with metal will be described. In the present embodiment, the metal 5 is filled in each fine hole 4 of the dielectric substrate 2 by plating.

  Specifically, the main component of the metal 5 to be filled is gold (Au), silver (Ag), platinum (Pt), nickel (Ni), titanium (Ti), in which a localized plasmon phenomenon is effectively generated, or Examples thereof include gold (Au) and silver (Ag). Furthermore, it is also possible to select two or more kinds of metals 5 among these and sequentially fill them.

  Here, in the step of filling the metal 5 in each microhole 4, it is possible to further enhance the localized plasmon effect by forming the insulator layer 6 on the top of the filled metal 5. Specifically, the insulator layer 6 may be an alumina layer.

  As shown in FIG. 1C, since the anodized metal body 3 functions as an electrode, metal is deposited from the bottom 4b of each microhole 4 in the vicinity of the anodized metal body 3. However, since the dielectric base material 2 is difficult to flow electricity, the filling state of the metal 5 in each fine hole 4 varies.

  Here, the filling of the metal 5 into each fine hole 4 is not limited to that by plating. The metal 5 may be filled in each fine hole 4 by vapor deposition, vapor deposition and subsequent annealing and sputtering, or by pouring a solution containing the metal 5 into each fine hole 4 and solvent drying. Is possible.

  Next, the process of depositing the metal 7 that can be an electrode will be described. In the present embodiment, after filling each minute hole 4 with a metal 5, a metal 7 that can serve as an electrode is deposited on the surface 2 a of the dielectric substrate 2.

  Specifically, the metal 7 that can be an electrode is not particularly limited, and may be the same metal as the metal 5 used in the above filling process.

  Examples of the method for depositing the metal 7 that can serve as an electrode include vapor deposition, sputtering, and a method of pouring a metal-containing solution that serves as an electrode and drying the solution. In this case, it is desirable to deposit until the film thickness of about 50 nm is formed from the opening 4a of each fine hole 4 in order to fully exhibit the effect as an electrode.

  Next, the process of removing the dielectric base material 2 from the back surface 2b side of the dielectric base material until the metal 5 filled in each microhole 4 is exposed will be described. In the present embodiment, the anodized metal body 3 and the dielectric base material 2 are removed from the back surface 2b side of the dielectric base material 2.

  As a specific method for removing the anodized metal body 3 and the dielectric base material 2, in the case of an aluminum and alumina layer, a method of removing by immersing in phosphoric acid at about 20 ° C. for about several minutes can be mentioned.

  The exposed surface 2c of the dielectric substrate 2 is formed by removing the anodized metal body 3 and the dielectric substrate 2 from the back surface 2b side of the dielectric substrate 2, and the bottom 4b of each fine hole 4 is further formed. Is removed, the metal 5 is exposed substantially uniformly from the second opening 4d.

  Here, the step of removing the anodized metal body 3 and the dielectric base material 2 may be performed after the step of filling the metal 5 in each fine hole 4, and is a step of depositing the metal 7 that can be an electrode. It may be before.

  Next, the process of forming the head portion 9a having a diameter 9b larger than the hole diameter 4c of each fine hole 4 by plating will be described. In this embodiment, the part which forms the head part 9a of the metal body 9 by the plating process is the metal part 5a exposed by the above-described removal process.

  Specifically, the metal to be plated is not particularly limited, and may be the same metal as the metal 5 used in the above filling process.

  The exposed metal portion 5a is plated using a metal 7 that can be an electrode deposited on the surface 2a of the dielectric substrate 2 as an electrode. The plating process is performed until the diameter 9b of the head 9a is larger than the hole diameter 4c of each fine hole 4.

  Specifically, gold (Au) is plated on the exposed metal portion 5a. In this case, it is desirable to continue the plating process until the gap 9c between the heads 9a becomes 10 nm or less. For example, the plating process is performed by measuring the distance between the heads 9a of the metal body 9 with an electron microscope in advance, so that the gap 9c between the heads 9a of most metal bodies 9 is 10 nm or less. By measuring the time, the plating process time is managed based on the measurement result.

  Here, FIGS. 1G to 1I show the respective steps in the case where the insulator layer 6 is formed on the filled metal 5 in the step of filling the metal 5 in each microhole 4 as described above. Is shown.

  FIG. 2 shows a second embodiment of the present invention. The first embodiment is a metal in which the step of removing the dielectric substrate 2 from the back surface 2b side of the dielectric substrate 2 until the metal 5 filled in each microhole 4 is exposed can serve as an electrode. The difference is that it is performed before the step 7 of depositing. 2 (g) to 2 (i) show the respective steps when the insulator layer 6 is formed on the filled metal 5 in the step of filling the metal 5 into each microhole 4 as described above. It is shown.

  FIG. 3 shows a third embodiment of the present invention. The first embodiment is different from the first embodiment in that, in the step of filling the metal 5 in each fine hole 4 of the dielectric substrate 2, two or more kinds of metals 5 are filled as described above. For example, as shown in FIG. 3 (c), after filling with silver, as shown in FIGS. 3 (d) and 3 (g), gold (upper part in the figure) is filled to prevent oxidation of silver. However, it is possible to use silver that effectively produces a plasmon enhancing effect. Alternatively, as shown in FIG. 3 (c), after filling with gold, as shown in FIGS. 3 (d) and 3 (g), by filling an inexpensive material (upper part in the figure), the head 9a becomes The cost can be reduced by making only the formed portion gold. 3 (g) to 3 (i) show the respective steps in the case where the insulator layer 6 is formed on the filled metal 5 in the step of filling the metal 5 into each fine hole 4 as described above. Is shown.

  FIG. 4 is a diagram illustrating a process of creating a support.

  4A shows a step of depositing a metal 7 that can be an electrode, and FIG. 4B shows a support 8 formed on a deposition surface 7a of the metal 7 that can be an electrode in order to facilitate handling and the like. FIG. 4C shows a process of removing the anodized metal body 3 and the dielectric base material 2 from the back surface 2b side of the dielectric base material 2 after the support 8 is formed. In FIG. 4, the step of forming the head 9a is omitted.

  Here, the step of creating the support 8 can be included in each embodiment of the present invention.

  Specifically, the support 8 may be a conductive metal or a non-conductive metal, but is preferably a conductive metal.

  According to the manufacturing method of the present invention, the bottom 4b of each microhole 4 is removed by removing from the back side of the dielectric substrate 2 in which the metal 5 is filled in each microhole 4, and the inside of each microhole 4 The metal 5 filled with is exposed from the exposed surface 2c of the dielectric substrate 2 substantially uniformly. By forming the head portion 9a of the metal body 9 by plating the metal portion 5a exposed substantially uniformly, the head portion 9a of the metal body 9 is formed substantially simultaneously. Therefore, it is possible to manufacture the fine structure 1 including the metal body 9 having the head portion 9a having a uniform diameter 9b by the plating process without being affected by the variation in the filling state of the metal 5 in each fine hole 4. Become.

  Furthermore, the portions filled in the fine holes 4 of each metal body 9 have variations, and the wavelength region in the electric field enhancement effect is expanded.

Schematic diagram showing the first embodiment of the present invention Schematic diagram showing a second embodiment of the present invention Schematic diagram showing a third embodiment of the present invention Schematic diagram showing the process of creating a support

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fine structure 2 Dielectric base material 2a Front surface 2b Back surface 2c Exposed surface 4 Micro hole 4a Open hole 4b Bottom 5 Metal 5a Exposed metal part 6 Insulator layer 7 Metal which can become an electrode 9 Metal body 9a Head part 9b Head diameter 9c gap

Claims (5)

A dielectric substrate having a plurality of micropores, a metal body having a size capable of generating localized plasmons, having a portion filled in each micropore and a head protruding from each micropore. A method of manufacturing a microstructure provided with,
Preparing a dielectric substrate having a plurality of bottomed micropores on the surface (A);
A step (B) of filling the fine holes with metal;
Depositing a metal that can serve as an electrode on the surface of the dielectric substrate (C);
Removing the dielectric substrate from the back side of the dielectric substrate until the metal filled in the bottomed micropores is exposed (D);
And (E) forming the head having a diameter larger than the hole diameter of the fine hole by plating on the exposed portion.   In step (A), an anodized base material having a plurality of bottomed micropores formed on the anodized metal body by anodizing the anodized metal body as the dielectric base material. The method for producing a fine structure according to claim 1, wherein the fine structure is used.   3. The fine structure according to claim 1, wherein in the step (E), the plating process on the exposed portion is continued until a gap between the heads of the metal body is 10 nm or less. Production method.   The method for manufacturing a microstructure according to any one of claims 1 to 3, further comprising forming an insulator layer on the filled metal in the step (B).   5. The method for manufacturing a microstructure according to claim 1, wherein in step (B), two or more kinds of metals having different materials are prepared and sequentially filled with the metals. 6.

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