WO2019146692A1 - Analysis substrate - Google Patents

Analysis substrate Download PDF

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Publication number
WO2019146692A1
WO2019146692A1 PCT/JP2019/002253 JP2019002253W WO2019146692A1 WO 2019146692 A1 WO2019146692 A1 WO 2019146692A1 JP 2019002253 W JP2019002253 W JP 2019002253W WO 2019146692 A1 WO2019146692 A1 WO 2019146692A1
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Prior art keywords
metal
film
particles
substrate
metal film
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PCT/JP2019/002253
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French (fr)
Japanese (ja)
Inventor
啓 篠塚
紘太郎 大
匠悟 三浦
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王子ホールディングス株式会社
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Publication of WO2019146692A1 publication Critical patent/WO2019146692A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/65—Raman scattering
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/64—Fluorescence; Phosphorescence

Definitions

  • the present invention relates to a substrate for analysis.
  • Priority is claimed on Japanese Patent Application No. 2018-010683, filed January 25, 2018, the content of which is incorporated herein by reference.
  • Raman spectroscopy has a very low intensity of Raman scattered light. It is considered to use surface enhanced Raman scattering (SERS) for the improvement.
  • SERS is a phenomenon in which the intensity of Raman scattered light of a molecule to be measured adsorbed is significantly enhanced by the electric field enhancement by surface plasmon resonance on a metal surface such as Au or Ag.
  • the use of electric field enhancement by surface plasmon resonance is also considered in optical analysis methods other than Raman spectroscopy and infrared absorption spectroscopy and fluorescence spectroscopy.
  • the signal amplification apparatus for Raman spectroscopy analysis provided with a metal film provided with a metal film (patent document 1).
  • An electric field enhancing element including a metal layer, a dielectric layer provided on the metal layer, and a plurality of metal particles provided on the dielectric layer, wherein the plurality of metal particles are It has a periodic arrangement capable of exciting propagating surface plasmons propagating through the interface between the metal layer and the dielectric layer, and the propagating surface plasmons and localized surface plasmons excited by the metal particles are electromagnetic. Interact with each other, and the resonance wavelength of each surface plasmon is different, and in the spectrum of the reflected light when the electric field enhancing element is irradiated with white light, the half bandwidths of the first absorption region and the second absorption region satisfy a specific relationship.
  • An electric field enhancing element in which the wavelength of excitation light of the electric field enhancing element is included in the range of the second absorption region Patent Document 2.
  • the device of Patent Document 1 utilizes propagating surface plasmons, and thus has the advantage that the variation of the electric field distribution on the nano-periodic structure is small, but the enhancement effect is due to the electric field enhancement solely by the propagating surface plasmons. Has the disadvantage of being low.
  • the electric field enhancing element of Patent Document 2 the propagating surface plasmon and the localized surface plasmon are combined, the electric field distribution is homogenized by the propagating surface plasmon, and the localized electric surface plasmon is enhanced. By doing this, it is a configuration that combines the advantages of the propagation type and the localized type, and it is possible to achieve both uniformity and strength to some extent.
  • the molecule to be measured of the sample can not approach the metal film surface with the highest electric field enhancing effect of the propagating surface plasmon.
  • the metal particles are arranged in the arrangement necessary for exciting the propagating surface plasmon, the distance between the particles is required to utilize the electric field enhancement utilizing the gap between the metal particles having a large effect as the localized surface plasmon. Too large is also mentioned as a disadvantage.
  • An object of the present invention is to provide a substrate for analysis which can carry out optical analysis with high sensitivity utilizing electric field enhancement by surface plasmon resonance.
  • An analytical substrate comprising: [2] The analytical substrate of [1], wherein the two-dimensional lattice structure is a triangular lattice structure or a square lattice structure.
  • a plurality of the metal films are provided in the form of island-like gaps having a length of 1 ⁇ m or less in the major axis direction in the metal film, and a plurality of metal is not present and the first surface of the substrate is exposed
  • the present invention it is possible to provide an analytical substrate capable of highly sensitively performing optical analysis utilizing electric field enhancement by surface plasmon resonance.
  • the clear difference from Patent Document 2 is that, in the present invention, the measurement target molecule of the sample can approach the metal film surface with the highest electric field enhancing effect of the propagating surface plasmon. Because of this difference, the present invention is superior to the prior art in the enhancement effect of Raman scattered light.
  • FIG. 5 is a partial cross-sectional view schematically showing a IV-IV cross-section in FIG. 4 (however, illustration of metal nanoparticles is omitted). It is a scanning electron microscope image of the board
  • FIG. 1 is a cross-sectional view schematically showing an analysis substrate according to a first embodiment of the present invention.
  • FIG. 2 is a top view schematically showing an analysis substrate according to an example of the present embodiment.
  • FIG. 3 is a perspective view of the analysis substrate shown in FIG. However, the illustration of the metal nanoparticles is omitted in FIGS.
  • the analysis substrate 10 of the present embodiment includes a substrate 1, a metal film 3 provided on the first surface 1 a of the substrate 1, and a plurality of metal nanoparticles 5 dispersed on the metal film 3.
  • the first surface 1a of the substrate 1 has a two-dimensional lattice structure.
  • the metal film 3 is formed along the first surface 1a. Therefore, the surface of the metal film 3 provided on the first surface 1a also has a two-dimensional lattice structure.
  • the metal film 3 and the plurality of metal nanoparticles 5 are in contact with each other.
  • the substrate 1 At least the first surface 1a of the substrate 1 is made of a dielectric or a semiconductor.
  • the substrate 1 may be, for example, a substrate made of a dielectric or a semiconductor, and two or more of the conductor layer, the dielectric layer, and the semiconductor layer may be stacked such that the first surface is a dielectric or a semiconductor. It may be a multilayer substrate.
  • the dielectric or semiconductor is not particularly limited, and may be a known material in applications such as a substrate for analysis.
  • a substrate made of only a dielectric or a semiconductor is used as the substrate 1 and, for example, a quartz substrate, various glass substrates such as alkali glass and non-alkali glass, sapphire substrate, silicon (Si) substrate, silicon carbide Examples include substrates made of inorganic substances such as SiC), and substrates made of organic substances such as polymethyl methacrylate, polycarbonate, polystyrene, polyolefin resin, and polyester resin.
  • the thickness of the substrate 1 is not particularly limited, and may be, for example, 0.1 to 5.0 mm. The thickness of the substrate 1 is measured by a general caliper measurement method established in JIS B7507.
  • the two-dimensional lattice structure of the first surface 1 a is for providing a two-dimensional lattice structure on the surface of the metal film 3, and is set according to the desired two-dimensional lattice structure on the surface of the metal film 3.
  • the metal constituting the metal film 3 may be any metal that can generate electric field enhancement by surface plasmon resonance, and examples thereof include gold, silver, aluminum, copper, platinum, alloys of two or more of these, and the like.
  • the sheet resistance of the surface of the metal film 3 at 25 ° C. (hereinafter, “sheet resistance of the surface at 25 ° C.” may simply be referred to as “sheet resistance of the surface”) is 5000 ⁇ / ⁇ or less, and 3 to 5000 ⁇ . / ⁇ is preferable, 3 to 500 ⁇ / ⁇ is more preferable, and 3 to 300 ⁇ / ⁇ is the most preferable.
  • the sheet resistance of the surface of the metal film 3 being equal to or less than the upper limit value indicates that the metal film 3 is a continuous film. When the sheet resistance of the surface of the metal film 3 is within this range, the metal film 3 is not completely divided even though it has nanogaps due to the non-film formation region G described later.
  • the sheet resistance of the surface of the metal film 3 is less than or equal to the above upper limit value because the distance between the metal surfaces 3 a facing each other via the non-film formation region G is In the range of 1 to 20 nm, more specifically in the range of 1 to 10 nm, and more specifically in the range of 1 to 5 nm.
  • the metal film 3 is a discontinuous film (for example, one composed of a plurality of metal films dispersed in an island shape), the sheet resistance of the surface does not become 5000 ⁇ / ⁇ or less.
  • the sheet resistance ( ⁇ / ⁇ ) of the surface of the metal film 3 is a value at 25 ° C. Specifically, the sheet resistance is the electrical resistance ( ⁇ ) when current flows from one end to the opposite end of a square area of any size on the surface of the metal film 3 under the condition of 25 ° C. . The details are as shown in Examples described later.
  • the metal film 3 has a two-dimensional lattice structure that follows the first surface 1 a of the substrate 1.
  • “follow” means that the position of the convex portion or the concave portion in the two-dimensional lattice structure on the surface of the metal film 3 substantially coincides with the position of the convex portion or the concave portion in the two-dimensional lattice structure of the first surface 1 a of the substrate 1 Indicates that.
  • the “two-dimensional lattice structure” is a periodic uneven structure in which a plurality of convex portions or concave portions are periodically arranged in two dimensions. Two-dimensionally arranged indicates that the plurality of convex portions or concave portions are arranged in two or more directions. Note that a periodic uneven structure in which a plurality of projections or depressions are periodically arranged in one dimension is also referred to as a one-dimensional lattice structure. The arrangement in one dimension indicates that the arrangement direction of the plurality of projections or depressions is one direction.
  • the propagation type surface plasmon of the metal surface is a surface electromagnetic field accompanied by a compressional wave of free electrons generated by light (excitation light such as a laser used in Raman spectroscopy) incident on the metal surface.
  • light excitation light such as a laser used in Raman spectroscopy
  • the metal surface is flat, propagating surface plasmon resonance is not induced because the dispersion curve of the surface plasmon present on the metal surface does not cross the dispersion line of light.
  • the dispersion straight line of light (diffracted light) diffracted by this periodic uneven structure intersects with the dispersion curve of the surface plasmon, and the propagating surface plasmon resonance is induced .
  • the periodic uneven structure is a one-dimensional lattice structure (for example, a line and space structure in which a plurality of grooves (concave portions) or convex lines (convex portions) are arranged in parallel).
  • Optical analysis using electric field enhancement by surface plasmon resonance can be performed more sensitively than in some cases.
  • a tetragonal lattice structure in which the arrangement direction is two directions and the crossing angle is 90 °, and the arrangement direction is three directions and the crossing angle is 60 ° also referred to as a hexagonal lattice.
  • the shape of the convex portion constituting the two-dimensional lattice structure is, for example, a cylindrical shape, a conical shape, a truncated cone shape, a sine wave shape, a hemispherical shape, a substantially hemispherical shape, an ellipsoidal shape, or a derivative shape based on them It may be.
  • the shape of the concave portion constituting the two-dimensional lattice structure may be, for example, a shape obtained by inverting the shape of the convex portion mentioned above.
  • a triangular lattice structure is preferable because it can induce propagating surface plasmon resonance with higher efficiency.
  • the two-dimensional lattice structure of the surface of the metal film 3 is a triangular lattice structure constituted of a plurality of truncated cone-shaped convex portions 3c as shown in FIGS.
  • the height of the convex portion 3c is preferably 15 to 150 nm, and more preferably 30 to 80 nm. If the height of the convex portion 3c is equal to or more than the lower limit value of the above range, the two-dimensional lattice structure on the surface of the metal film 3 sufficiently functions as a diffraction grating, and propagation type surface plasmon resonance can be induced.
  • the metal film 3 tends to be a continuous film. Also in the case where the convex portion 3c has another shape, the preferable height is approximately the same.
  • the two-dimensional lattice structure on the surface of the metal film 3 is composed of a plurality of recesses, the preferred depth of the recesses is approximately the same as the preferred height of the protrusions 3c. Precisely, the optimum value of the height of the convex portion 3c is determined by the volume fraction and the dielectric constant of the convex portion 3c which interacts with the electromagnetic field by the surface plasmon.
  • the height of the convex portion 3c is the distance in the vertical direction to the average value of the top surfaces of the truncated cones of the three convex portions starting from the central point equidistant from the adjacent three convex portions as AFM (atomic force microscope Measured by) etc.
  • AFM atomic force microscope Measured by
  • AFM images of 5 ⁇ m ⁇ 5 ⁇ m are acquired for these five measurement regions, and the above-mentioned three-point center depths of nine locations randomly measured for each AFM image are measured. Since the AFM probe may generate anisotropy in the image depending on the scan direction, as shown in Fig.
  • the length measurement is performed by creating profile images in three directions D M1 to D M3 and in each direction Perform at three measurement points, for a total of nine measurement points.
  • the average value of the measured values obtained at the nine measurement points is taken as the measured value of one measurement area, the measured values of the five measurement areas are similarly determined, and the average of the measured values of the five measurement areas is calculated.
  • the height of the projection 3c is obtained.
  • Each of D M1 to D M3 is a direction substantially orthogonal to each of the three arrangement directions E M1 to E M3 of the convex portions 3 c on the main surface of the metal film 3 (Because the actual lattice arrangement has some distortion, Not necessarily orthogonal).
  • the heights of the projections of the other shapes and the depths of the recesses are also measured by the same measurement method.
  • the pitch ⁇ of the convex portions 3c in the arrangement direction of the convex portions 3c is designed to correspond to the wavelength ⁇ i of the incident light (excitation light).
  • the real part of the relative dielectric constant of metal at k i is ⁇ 1
  • the real part of the relative dielectric constant of the specimen is ⁇ 2 .
  • the metal forming the convex portion 3c is gold (Au)
  • the sample is a dried organic substance ( ⁇ 2 2.22.25)
  • k spp 16.6 ⁇ m ⁇ 1
  • ⁇ 438 nm It is.
  • the convex portions 3c may be fabricated as close as possible to the pitch ⁇ .
  • the two-dimensional lattice arrangement is a square lattice or one-dimensional lattice arrangement (line and space)
  • the following equation 3 may be used instead of the equation 2.
  • Laser light sources used as incident light include ones corresponding to various wavelengths such as 785, 633, 532, 515, 488, and 470 nm.
  • gold Au
  • a light source larger than the wavelength of about 500 nm and a light source smaller than the wavelength about 500 nm or so as a metal species constituting the sea-island structure, metal nanoparticles and periodic uneven structure.
  • silver Au
  • metal enhanced species other than gold (Au) and silver (Ag) may be able to obtain the surface enhanced Raman scattering effect, which is not necessarily limited to the above.
  • the preferred pitch is the same as in the case where the projections 3c have other shapes.
  • the preferred pitch of the recesses in the arrangement direction of the recesses is the same as the preferred pitch of the protrusions 3c.
  • the pitch of the convex portions 3c is obtained by measuring the horizontal distance between the center points of two adjacent truncated conical projections by AFM (atomic force microscope) or the like. For measurement, five two-dimensional lattice structure surfaces separated by 100 ⁇ m or more are used. AFM images of 5 ⁇ m ⁇ 5 ⁇ m are acquired for these five measurement regions, and the distance between the two points of nine locations randomly extracted for each AFM image is measured. Since the AFM probe may cause anisotropy in the image depending on the scan direction, as shown in Fig. 2, the profile image is created in three directions E M1 to E M3 as shown in FIG. Perform at 9 points in total.
  • AFM atomic force microscope
  • the average value of the measurement values obtained at the nine measurement points is taken as the measurement value of one measurement area, and the average of the measurement values of the five measurement areas is determined to obtain the pitch of the convex 3c.
  • the pitches of convex portions of other shapes and the pitches of concave portions are also measured by the same measurement method.
  • Aspect A A plurality of non-film-forming areas provided as an island-like gap shape having a length of 1 ⁇ m or less in the major axis direction in the metal film and the first surface 1a of the substrate 1 is exposed without metal Metal film with.
  • Aspect B a metal film not having the non-film formation region.
  • the metal film 3 is a metal film of aspect A (hereinafter, also referred to as a metal film 3A), the combined use of the propagating surface plasmon and the enhanced electric field by the localized surface plasmon, or the propagating surface plasmon and the localized surface Optical analysis can be performed more sensitively by utilizing resonance coupling (coupling) of enhanced electric fields by plasmons.
  • the metal film 3 is a metal film of aspect B (hereinafter, also referred to as a metal film 3B)
  • optical analysis can be performed with higher sensitivity by utilizing an enhanced electric field by propagating surface plasmons.
  • FIG. 4 is an enlarged top view schematically showing the surface on the metal film 3 side of the analysis substrate 10 when the metal film 3 is the metal film 3A
  • FIG. 5 is an IV in FIG. 4 of this analysis substrate.
  • FIG. 4 is a partial cross-sectional view schematically showing a cross-section of FIG. However, in FIGS. 4 to 5, the illustration of the metal nanoparticles is omitted.
  • the metal film 3A has a plurality of non-film formation regions G.
  • the plurality of non-film formation regions G are dispersedly provided in the metal film 3A as an island-like gap shape whose length in the long axis direction is 1 ⁇ m or less.
  • a region other than the non-film formation region G of the metal film 3 is a film formation region.
  • the non-film formation region G is a region in which the first surface 1 a is exposed without the presence of metal. That is, it is a gap (gap) penetrating the metal film 3A in the thickness direction.
  • a region (for example, a region S in FIG. 5) which is not a void penetrating the metal film 3A even if metal does not exist in a part in the thickness direction does not correspond to the non-film formation region G. It is a film formation area.
  • the non-film formation area G is an island-shaped gap in a top view, and the plurality of non-film formation areas G may be independent of one another or may be several in number. Absent. Therefore, as shown in FIG. 5, the non-film formation area G is surrounded by the metal surface 3a, and the metal surfaces 3a face each other through the non-film formation area G.
  • the distance between the metal surfaces facing each other through the non-film formation area G, that is, the width of the non-film formation area G is usually extremely small, for example, on the order of several nanometers to several tens of nanometers. Between such metal surfaces 3a, electric field enhancement can be generated by superposition of electric fields by localized surface plasmons. In particular, when the width of the non-film formation region G is one digit nanometer, extremely strong electric field enhancement is obtained.
  • the distance between the metal surfaces 3a facing each other through the non-film formation region G is preferably 1 to 20 nm, more preferably 1 to 10 nm, and still more preferably 1 to 5 nm. If the distance between the metal surfaces 3a is within the above range, the electric field enhancing effect by localized surface plasmon resonance is more excellent.
  • the metal surface surrounding the non-film formation region G is an inclined surface inclined with respect to the thickness direction of the metal film 3 as shown in FIG. 5, there is a distribution in the distance between the metal surfaces 3a.
  • the maximum value of the distance between the metal surfaces 3a is below the said preferable upper limit.
  • the minimum value of the distance between the metal surfaces 3a is more than the said preferable lower limit.
  • the distance between the metal surfaces 3a is measured by the method described in the examples to be described later.
  • the thickness of the metal film 3A is preferably 3 to 40 nm, more preferably 4 to 30 nm, and most preferably 5 to 20 nm as the average thickness of the region other than the non-film formation region G, ie, the film formation region. If the thickness of the metal film 3A is within the above range, the non-film formation region G is provided, and the distance between the metal surfaces opposed via the non-film formation region G, the non-film formation region with respect to the total area of the metal film 3A It tends to become the metal film 3A in which the ratio of the area of G is within the above preferable range. If the thickness of the metal film 3A is equal to or more than the lower limit value, the sheet resistance of the surface of the metal film 3A is likely to be equal to or less than the upper limit value.
  • the thickness of the metal film 3A (average thickness of the film formation region) is a value calculated from the film formation rate obtained by the following method. First, a flat substrate such as a single crystal silicon substrate or the like and having a center line average roughness Ra of 1 nm or less obtained by atomic force microscope (AFM) is prepared, and is masked with a tape etc. After forming a film for a fixed time of about several tens of nm and removing the mask, the film thickness is measured by AFM. From the above information, the deposition rate (deposition thickness per unit time (nm / min)) is determined. Once the film formation rate is determined, the thickness of the metal film 3A can be calculated from the film formation rate and the film formation time for forming the metal film 3A.
  • AFM atomic force microscope
  • the thickness of the film may be measured using a stylus type profilometer instead of AFM. In this case, similar results can be obtained, but in the case where the measurement values by the AFM and the stylus type profilometer differ, in the present invention, the measurement values by the AFM are adopted.
  • the thickness of the metal film 3A for convenience, a microscopic image of a cross-sectional sample of the substrate including the metal film 3A is acquired using a transmission electron microscope (TEM), and the thickness of the metal film 3A is measured in the image. It may be measured by a method. Similar results are obtained in this case as well. Since this method does not need to measure information such as the film formation rate in advance, this method is an effective means for samples whose manufacturing conditions and the like are unknown.
  • an extremely thin scratch is formed on the surface of the metal film 3A using a knife or the like, and the depth of the scratch is measured by AFM.
  • the method of lengthening is effective. Since the metal film 3A is extremely thin, it is possible to form a scratch in which the substrate is exposed with a relatively weak force.
  • the thickness of the metal film 3B is more preferably 40 to 400 nm or less, further preferably 50 to 200 nm. If the thickness of the metal film 3B is equal to or more than the above lower limit value, it tends to be a metal film having no non-film formation region. If the thickness of the metal film 3BA is within the above range, the sheet resistance of the surface of the metal film 3A is likely to be within the range. The thickness of the metal film 3B is measured in the same manner as the thickness of the metal film 3A.
  • the metal constituting the metal nanoparticles 5 may be any metal as long as it can generate electric field enhancement by surface plasmon resonance, and examples thereof include gold, silver, aluminum, copper, platinum, alloys of two or more of these, and the like.
  • the shape of the metal nanoparticles 5 is not particularly limited, and may be, for example, spherical, needle-like (rod-like), flake-like, polyhedral-like, ring-like, hollow (in the center part, a cavity or a dielectric exists), dendritic crystals, Other irregular shapes are also included. At least a part of the plurality of metal nanoparticles 5 may be aggregated to form a secondary particle.
  • the average primary particle diameter of the metal nanoparticles 5 is 5 to 100 nm, preferably 5 to 80 nm, and more preferably 5 to 40 nm. If the average primary particle diameter of the metal nanoparticles 5 is within the above range, the electric field enhancing effect by localized surface plasmon resonance is excellent.
  • TEM transmission electron microscope
  • AFM atomic force microscope
  • the average primary particle size of the metal nanoparticles 5 may be conveniently measured by a particle size distribution analyzer by a dynamic light scattering method.
  • a particle size distribution analyzer by a dynamic light scattering method.
  • secondary particles aggregates in which primary particles are aggregated
  • a plurality of peaks are generated in the particle size distribution curve, and therefore the peak with the smallest particle diameter is the target particle diameter.
  • the same result as the measurement method using the above SEM can be obtained.
  • a measuring method using a microscopic means such as SEM is useful when analyzing the surface of a substrate for analysis as a product later, and a measuring method by dynamic light scattering method is useful for producing an analytical substrate .
  • the shortest distance between two adjacent metal nanoparticles 5 arranged on the metal film 3 at a distance is preferably 1 to 20 nm, more preferably 1 to 10 nm, and still more preferably 1 to 5 nm. If the shortest distance is within the above range, electric field enhancement occurs by localized surface plasmon resonance between the metal nanoparticles 5, and high sensitivity Raman spectroscopy of the measurement target molecules adsorbed between the metal nanoparticles 5 Analysis is possible. In addition, even if the metal nanoparticles 5 are grounded to the metal film 3, minute gaps between the metal film 3 and the metal nanoparticles 5 are generated in the vicinity of the contact points, so here also by localized surface plasmon resonance. Electric field enhancement occurs to enable highly sensitive Raman spectroscopy.
  • the said shortest distance acquires the microscopic image of the surface sample of the board
  • SEM scanning electron microscope
  • TEM transmission electron microscope
  • AFM atomic force microscope
  • Examples of the method for producing the analysis substrate 10 include the following production method (I).
  • step I-1 a plurality of regions where metal is not deposited remain on the first surface 1a as island-like gaps having a length of 1 ⁇ m or less in the long axis direction, and sheet resistance on the surface of the metal film
  • the metal film 3A is obtained. If the deposition of metal is continued without completion, the non-film formation region G disappears, and the unevenness of the film surface becomes small, and the metal film 3B having a flat surface is formed.
  • an original plate having a two-dimensional lattice structure formed on the surface or a transferred product thereof can be used as the substrate 1.
  • Such an original plate or a transferred product thereof may be one produced by a known production method or a commercially available one.
  • the original plate is obtained by forming a two-dimensional lattice structure on the surface of the original plate.
  • the original plate is the same as the substrate 1 except that the original plate does not have a predetermined two-dimensional lattice structure on the surface.
  • a method of forming a two-dimensional lattice structure on the surface of the original plate for example, dry etching (colloidal lithography) using a single particle film as an etching mask, electron beam lithography, mechanical cutting, laser thermal lithography, Nanoimprint method from a transfer master having a two-dimensional lattice structure on the surface, which is manufactured by the interference exposure method, more specifically, the two-beam interference exposure method, the reduction exposure method, the anodic oxidation method of alumina, and any of them. Etc.
  • a method of forming a two-dimensional lattice structure various methods can be applied, such as a photolithography method combining electron beam drawing and dry etching, a nanoporous alumina anodic oxidation method, or a nanoimprint method using a master obtained therefrom.
  • a dry etching method (colloidal lithography method) using a single particle film as an etching mask is preferable in that a microstructure can be produced with a large area and low cost.
  • the colloidal lithography method can easily produce a plurality of structures with different pitches, and has an advantage that structure optimization and functional verification can be performed quickly.
  • a step of disposing a single particle film on an original plate (a substrate before forming a two-dimensional lattice structure on the surface) (a single particle film disposing step); It can carry out by the manufacturing method including the process (dry etching process) which dry-etches a single particle film and the said original plate.
  • the monoparticulate film and each step will be described in detail later.
  • the method of depositing the metal on the first surface 1a is not particularly limited, and examples thereof include dry methods such as vapor deposition, and wet methods such as electrolytic plating and electroless plating.
  • dry methods include various vacuum sputtering methods, physical vapor deposition methods (PVD) such as vacuum deposition methods, and various chemical vapor deposition methods (CVD).
  • PVD physical vapor deposition methods
  • CVD chemical vapor deposition methods
  • metal film deposition metal deposition
  • a plurality of metal particles adhere to the entire first surface 1a, and the metal particles are joined by growth to form fine particles.
  • Plural island-shaped metal films are formed.
  • adjacent metal films form larger clusters, and the area and thickness of the metal films increase.
  • the region where the metal is not deposited on the first surface 1a becomes narrower.
  • the film formation is completed in a state in which the area where the metal is not deposited remains like an island and the value of the surface sheet resistance of the formed metal film falls within the above range (the metal film becomes a continuous film).
  • the aforementioned metal film 3A is obtained.
  • An area in which the island remains and in which the metal is not deposited is a non-film formation area G. If the deposition of metal is continued without completion, the non-film formation region G disappears and it becomes the metal film 3B.
  • a catalyst When a catalyst is dispersedly disposed on the first surface 1a in advance and a metal film is formed by electroless plating in that state, first, metal adheres to the periphery of the catalyst, and a plurality of fine island-shaped metal films are formed. Be done. As the electroless plating progresses, as in the case of the dry method, the metal films form larger clusters, and the region on which the metal is not deposited on the first surface 1a is narrowed.
  • the above-described metal film 3A is obtained by completing the film formation in a state where the region where metal is not deposited remains in an island shape and the surface sheet resistance value of the formed metal film is in the above range. An area in which the island remains and in which the metal is not deposited is a non-film formation area G. If the deposition of metal is continued without completion, the non-film formation region G disappears and it becomes the metal film 3B.
  • the metal film 3 is preferably a film formed by sputtering.
  • the fact that a plurality of regions where metal is not deposited remains in the form of islands on the first surface 1a is 100,000 times as large as with a high magnification microscope such as atomic force microscope (AFM) or scanning electron microscope (SEM) This can be confirmed by surface observation of the degree.
  • the sheet resistance of the surface of the metal film 3 at the end of the deposition is preferably 3 to 500 ⁇ / ⁇ , and most preferably 3 to 300 ⁇ / ⁇ .
  • the dispersion medium of the metal nanoparticle dispersion liquid may be any one as long as the metal nanoparticles 5 can be dispersed, and examples thereof include water, ethanol, and other organic solvents.
  • the content of the metal nanoparticles 5 in the metal nanoparticle dispersion may be, for example, 0.01 to 10.0 mass% with respect to the total mass of the metal nanoparticle dispersion, and further 0.1 to 1 It may be 0 mass%.
  • the metal nanoparticle dispersion may further contain citric acid, various inorganic salts, and the like as a dispersion stabilizer, as needed, as long as the effects of the invention are not impaired.
  • a coating method of a metal nanoparticle dispersion liquid it can select suitably from well-known coating methods, such as a spray method, a drop cast method, a dip coating method, a spin coat method, an inkjet printing method.
  • the spray method or the inkjet printing method is preferable in that metal nanoparticles can be densely and uniformly arranged on the substrate surface by metal nanoparticle dispersion.
  • step I-1 or after step I-2 when stored for a long time under normal environment (in air), contaminants in the air adhere to the metal structure on the substrate surface, and the effect of the present invention It may decrease. Therefore, storage is preferably performed in a vacuum vessel or an inert gas such as nitrogen or argon. If the effect of the present invention is reduced due to contaminants in the air, the substrate may be subjected to surface treatment such as ultraviolet (UV) / ozone to restore its function, if necessary. Good.
  • UV ultraviolet
  • the “single particle film” is a single layer film in which a plurality of particles are two-dimensionally arranged.
  • the material of the particles constituting the single particle film is not particularly limited, and may be an organic material, an inorganic material, or a composite material of an organic material and an inorganic material.
  • the organic material include thermoplastic resins such as polystyrene and polymethyl methacrylate (PMMA); thermosetting resins such as phenol resin and epoxy resin; and the like.
  • the inorganic material include carbon allotropes, inorganic carbides, inorganic oxides, inorganic nitrides, inorganic borides, inorganic sulfides, inorganic selenides and the like.
  • Examples of the carbon allotrope include diamond, graphite, fullerenes and the like.
  • Examples of inorganic carbides include silicon carbide and boron carbide.
  • Examples of the inorganic oxide include silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, zinc oxide, tin oxide, yttrium aluminum garnet (YAG) and the like.
  • Examples of the inorganic nitride include silicon nitride, aluminum nitride, boron nitride and the like.
  • Examples of inorganic borides include ZrB 2 and CrB 2 .
  • inorganic sulfides include zinc sulfide, calcium sulfide, cadmium sulfide, strontium sulfide and the like.
  • inorganic selenides include zinc selenide and cadmium selenide.
  • the material constituting the particles may be one kind or two or more kinds.
  • the average particle diameter of the particles constituting the single particle film corresponds to the pitch of the periodic uneven structure calculated by the above-mentioned method in accordance with the excitation wavelength used for the spectral analysis. If the average particle diameter of the particles is the above calculated value, propagation surface plasmons are easily induced.
  • the average particle diameter of the particles in a slurry state not constituting the single particle film can be determined by a conventional method from the peak obtained by fitting the particle size distribution determined by the particle dynamic light scattering method to a Gaussian curve It is the diameter.
  • the coefficient of variation (the value obtained by dividing the standard deviation by the average value) of the particle diameter of the particles constituting the single particle film is preferably 20% or less 10% or less is more preferable, and 5% or less is more preferable.
  • the coefficient of variation coefficient of particle diameter that is, small variation of particle diameter
  • misalignment D of the arrangement of particles is 10%. It is possible to obtain a highly accurate single particle film which is as follows.
  • a single particle film in which the misalignment D is 10% or less each particle is two-dimensionally close-packed, the particle spacing is controlled, and the accuracy of the alignment is high. Therefore, if such a single particle film is disposed on the original plate and dry etching is performed, a highly accurate two-dimensional lattice structure can be formed on the surface of the original plate.
  • the present invention is not limited to this, and a single particle film may be composed of particles having a large variation coefficient of particle diameter.
  • a single particle film may be configured using a mixture of a plurality of particle groups having different average particle sizes.
  • the deviation D of the arrangement of particles is defined by the following formula (1).
  • D [%]
  • A is an average particle diameter of particles constituting a single particle film
  • B is an average pitch between particles in the single particle film.
  • indicates the absolute value of the difference between A and B.
  • the average particle size of the particles is as defined above.
  • the pitch between particles is the distance between the apexes of two adjacent particles, and the average pitch is the average of these. If the particles are spherical, the distance between the apexes of two adjacent particles is equal to the distance between the centers of the two adjacent particles.
  • the average pitch B between particles in the single particle film is determined as follows. First, an atomic force microscope image or a scanning electron microscope image is obtained for a square region of 30 to 40 wavelengths of repeating units of a fine structure in a randomly selected region of a single particle film. For example, in the case of a single particle film using particles of 300 nm in particle diameter, an image of a region of 9 ⁇ m ⁇ 9 ⁇ m to 12 ⁇ m ⁇ 12 ⁇ m is obtained. Then, this image is waveform separated by two-dimensional Fourier transform to obtain an FFT image (fast Fourier transform image). Next, the distance from the zero-order peak to the first-order peak in the profile of the FFT image is determined.
  • FFT image fast Fourier transform image
  • the inverse of the calculated distance is the average pitch B 1 in this region.
  • Such processing is similarly performed on randomly selected areas of 25 areas or more having the same area in total, and average pitches B 1 to B 25 in each area are determined.
  • the average value of the average pitches B 1 to B 25 in the region of 25 or more places thus obtained is the average pitch B in the equation (1).
  • the respective regions are preferably selected to be separated by at least 1 mm, and more preferably selected to be separated by 5 mm to 1 cm. At this time, it is also possible to evaluate, for each image, the variation in pitch among particles in each image from the half width of the primary peak in the profile of the FFT image.
  • the single particle film disposing step is preferably performed by the Langmuir-Blodgett method (LB method).
  • LB method Langmuir-Blodgett method
  • This method combines the accuracy of single-layering, the simplicity of operation, the response to an increase in area, the reproducibility, etc., for example, the liquid thin film described in Nature, Vol. 361, 7 January, 26 (1993), etc. It is extremely superior to the so-called particle adsorption method described in U.S. Pat.
  • a water tank (trough) containing water as a liquid (hereinafter sometimes referred to as a lower layer liquid) for developing particles on the liquid surface is prepared, and the liquid Step of dropping a dispersion in which particles are dispersed in an organic solvent having a smaller specific gravity than water on a surface (dropping step) and step of forming a single particle film composed of particles by volatilizing the organic solvent (single particle A film formation process can be implemented by the method including the process (transfer process) which transfers the formed single particle film to a negative
  • particles having a hydrophobic surface are used as the particles so that the particles do not dip below the surface of the hydrophilic lower layer liquid.
  • a hydrophobic solvent is selected so that when the dispersion is dropped onto the liquid surface of the lower layer liquid, the dispersion will expand to the air-liquid interface of the air and the lower layer liquid without mixing with the lower layer liquid. Be done.
  • the particles having a hydrophobic surface and the organic solvent having a hydrophobic surface are selected, and the lower layer liquid is hydrophilic, but the particles having a hydrophilic surface and an organic solvent are used.
  • a hydrophilic solvent may be selected, and a hydrophobic liquid may be used as the lower layer liquid.
  • the organic solvent used for the dispersion is a hydrophobic one having a smaller specific gravity than water. It is also important that the organic solvent have high volatility.
  • organic solvents having a specific gravity smaller than water and being hydrophobic and having high volatility include chloroform, methanol (used as a material for mixing), ethanol (used as a material for mixing), isopropanol (used as a material for mixing), acetone (Used as a material for mixing) Volatile organic solvents comprising one or more kinds of methyl ethyl ketone, diethyl ketone, toluene, hexane, cyclohexane, ethyl acetate, butyl acetate and the like.
  • particles having an organic material such as polystyrene and having an originally hydrophobic surface may be used as the particles having a hydrophobic surface, and the particles having a hydrophilic surface are treated with a hydrophobicizing agent.
  • a hydrophobicizing agent for example, surfactants, metal alkoxides and the like can be used.
  • the method of using a surfactant as a hydrophobizing agent is effective for hydrophobization of a wide range of materials, and is suitable when the particles are made of an inorganic oxide or the like.
  • the method of using a metal alkoxide as a hydrophobizing agent is effective in hydrophobizing inorganic oxide particles such as aluminum oxide, silicon oxide and titanium oxide.
  • inorganic oxide particles such as aluminum oxide, silicon oxide and titanium oxide.
  • the present invention can be applied to particles having a hydroxyl group on the surface.
  • cationic surfactants such as hexadecyltrimethylammonium bromide and decyltrimethylammonium bromide
  • anionic surfactants such as sodium dodecyl sulfate and sodium 4-octylbenzene sulfonate
  • alkanethiols, disulfide compounds, tetradecanoic acid, octadecanoic acid and the like can be used.
  • an alkoxysilane is mentioned, for example.
  • the alkoxysilane monomethyltrimethoxysilane, monomethyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2 -(3,4-Epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane Silane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-meth
  • the hydrophobization treatment using a surfactant may be carried out by dispersing particles in a liquid such as an organic solvent or water, and may be carried out on particles in a dry state.
  • a liquid such as an organic solvent or water
  • particles to be hydrophobized may be added and dispersed in the above-mentioned volatile organic solvent, and then the surfactant may be mixed and dispersion may be continued.
  • the dispersion after such hydrophobization treatment can be used as it is as a dispersion for dropping onto the liquid surface of the lower layer liquid in the dropping step.
  • the particles to be hydrophobized are in the form of an aqueous dispersion
  • a surfactant is added to the aqueous dispersion to perform hydrophobization on the particle surface in the aqueous phase, and then an organic solvent is added to hydrophobize.
  • the method of oil phase extraction of the finished particles is also effective.
  • the dispersion (dispersion in which the particles are dispersed in the organic solvent) thus obtained can be used as it is as a dispersion to be dropped onto the liquid surface of the lower layer liquid in the dropping step.
  • a dispersion having high particle dispersibility By using a dispersion having high particle dispersibility, it is possible to suppress aggregation of particles in the form of clusters, and it becomes easier to obtain a single particle film in which each particle is densely packed in two dimensions.
  • chloroform when chloroform is selected as the organic solvent, it is preferable to use decyltrimethylammonium bromide as the surfactant.
  • a combination of ethanol and sodium dodecyl sulfate, a combination of methanol and sodium 4-octylbenzene sulfonate, a combination of methyl ethyl ketone and octadecanoic acid, and the like can be preferably exemplified.
  • the ratio of the particles to be hydrophobized to the surfactant is preferably such that the mass of the surfactant is 1/3 to 1/15 times the mass of the particles to be hydrophobized. In the case of such hydrophobization treatment, it is also effective to stir the dispersion during treatment or to irradiate the dispersion with ultrasonic waves in terms of improvement of the particle dispersibility.
  • the alkoxy group bonded to the metal atom in the metal alkoxide is hydrolyzed to form a hydroxyl group.
  • the alkoxysilyl group is hydrolyzed to form a silanol group (Si-OH).
  • Hydrophobization is performed by dehydrating condensation of the generated hydroxyl groups with hydroxyl groups on the particle surface. Therefore, it is preferable to carry out the hydrophobization treatment using a metal alkoxide in water.
  • the hydrophobization treatment is carried out in water as described above, it is preferable to stabilize the dispersion state of the particles before hydrophobization by using, for example, a dispersing agent such as a surfactant, depending on the kind of the dispersing agent. Since the hydrophobization effect of the metal alkoxide may be reduced, the combination of the dispersant and the metal alkoxide is appropriately selected.
  • a dispersing agent such as a surfactant
  • the particles are dispersed in water, and this is mixed with a metal alkoxide-containing aqueous solution (an aqueous solution containing a hydrolyzate of metal alkoxide),
  • a metal alkoxide-containing aqueous solution an aqueous solution containing a hydrolyzate of metal alkoxide
  • the reaction is carried out for a predetermined time, preferably 6 to 12 hours, with appropriate stirring in the range of ° C.
  • the reaction proceeds moderately, and a dispersion liquid of sufficiently hydrophobized particles can be obtained.
  • the silanol groups react with each other to combine the particles with each other, the particle dispersibility of the dispersion decreases, and in the obtained single particle film, the particles partially aggregate in a cluster 2 It is easy to become more than a layer.
  • the reaction is insufficient, the hydrophobicization of the particle surface also becomes insufficient, and in the operation of developing the particles to be described later on the water surface, problems occur that the particles settle in water, or the strength of the obtained single particle film decreases. It is not preferable because wrinkle-like defects occur.
  • the alkoxysilanes other than amine based hydrolyze under acidic or alkaline conditions it is necessary to adjust the pH of the dispersion to be acidic or alkaline during the reaction.
  • There is no limitation on the method of adjusting the pH but according to the method of adding an aqueous acetic acid solution having a concentration of 0.1 to 2.0% by mass, in addition to the promotion of hydrolysis, the effect of stabilizing the silanol group is also obtained.
  • the ratio of the particles to be hydrophobized to the metal alkoxide is preferably such that the mass of the metal alkoxide is 1/3 to 1/100 times the mass of the particles to be hydrophobized.
  • the volume of the organic solvent to be added is preferably 0.3 to 3 times the volume of the dispersion before addition of the organic solvent.
  • the dispersion (dispersion in which the particles are dispersed in the organic solvent) thus obtained can be used as it is as a dispersion to be dropped onto the liquid surface of the lower layer liquid in the dropping step.
  • the concentration of particles in the dispersion to be dropped to the lower layer solution is preferably 1 to 10% by mass.
  • the dropping speed of the dispersion is preferably 0.001 to 0.01 mL / sec.
  • the dispersion before dropping onto the liquid surface is precision filtered with a membrane filter or the like, and aggregated particles (secondary particles consisting of a plurality of primary particles) present in the dispersion Is preferred to be removed.
  • aggregated particles secondary particles consisting of a plurality of primary particles
  • a surface pressure sensor that measures the surface pressure of the single particle film in the transition step described in detail later; Even if an LB trough apparatus provided with a movable barrier that compresses a single particle film in the liquid surface direction is used, such a defect is not detected as a difference in surface pressure, and a high accuracy single particle film can be obtained. It becomes difficult.
  • Single particle film formation process When the dispersion liquid is dropped onto the liquid surface of the lower layer liquid in the dropping step, the solvent as the dispersion medium is volatilized, and the particles are spread in a single layer on the liquid surface of the lower liquid layer, and the particles are two-dimensionally dense Can be formed.
  • this single particle film is due to the self-organization of the particles.
  • the principle is that when particles are concentrated, surface tension acts due to the dispersion medium present between the particles, and as a result, the particles are not separated from each other, but are concentrated on the liquid surface of the lower layer liquid Automatically forms a single layer structure.
  • the formation of a single layer structure by such surface tension can be said to be mutual adsorption of particles due to the lateral capillary force.
  • surface tension acts to minimize the total length of the waterline of the particle group, and the three particles are based on an equilateral triangle. Stabilize in place.
  • the lower layer liquid it is preferable to use water as described above, and when water is used, relatively large surface free energy acts to form a dense single layer structure of particles once generated on the liquid surface. It becomes stable and easy to sustain.
  • the single particle film forming step is preferably performed under ultrasonic irradiation conditions.
  • the single particle film forming step is performed while irradiating ultrasonic waves from the lower layer solution to the water surface, mutual adsorption of particles is promoted, and a single particle film in which each particle is densely packed in two dimensions can be obtained.
  • the output of the ultrasonic wave is preferably 1 to 1200 W, more preferably 50 to 600 W.
  • the frequency of ultrasonic waves is not particularly limited, but for example, 28 kHz to 5 MHz is preferable, and 700 kHz to 2 MHz is more preferable.
  • the frequency is too high, energy absorption of water molecules starts, and a phenomenon that water vapor or water droplets rise from the water surface occurs, which is not preferable for the LB method. If the frequency is too low, the cavitation radius in the lower layer solution will be large, and bubbles will be generated in the water and will rise toward the water surface. When such bubbles accumulate under the monoparticle film, the flatness of the water surface is lost, which is disadvantageous for the LB method.
  • ultrasonic waves are applied, standing waves are generated on the water surface. If the output is too high at any frequency, or if the wave height of the water surface is too high due to the tuning conditions of the ultrasonic transducer and the transmitter, the single particle film is broken by the water wave, so care must be taken.
  • the frequency of ultrasonic waves is set appropriately in consideration of the above, it is possible to effectively promote the concentration of particles without destroying the monoparticle film being formed.
  • the particle size is small, for example, 100 nm or less, the natural frequency becomes very high, and it becomes difficult to give ultrasonic vibration as calculated. In such a case, it is possible to reduce the necessary frequency to a realistic range by performing calculations assuming that the natural vibration corresponding to the mass from the particle dimer to about 20 mer is given. .
  • the irradiation time of the ultrasonic waves may be sufficient to complete the rearrangement of the particles, and the required time changes depending on the particle diameter, the frequency of the ultrasonic waves, the water temperature, and the like. However, under normal preparation conditions, it is preferably performed for 10 seconds to 60 minutes, more preferably for 3 minutes to 30 minutes.
  • the advantages obtained by the ultrasonic irradiation include the effect of destroying the soft agglomerates of particles that are easily generated during preparation of the nanoparticle dispersion, point defects, line defects, or crystals that are easily generated during preparation of the nanoparticle dispersion, in addition to high-density packing of particles. There is an effect of repairing the metastasis etc. to some extent.
  • the single particle film formed on the liquid surface in the single particle film forming step is transferred onto the original plate in a single layer state.
  • the original plate is the same as the substrate 1 except that the two-dimensional lattice structure is not formed on the surface.
  • the hydrophobic original plate is lowered from above while being kept substantially parallel to the single particle membrane to form a single particle membrane.
  • an original plate is dipped in a substantially vertical direction in a lower layer solution in a water tank in advance, and the dropping step and the single particle film forming step described above are performed in this state to form a single particle film. Then, after the single particle film forming step, the single particle film can be transferred onto the original plate by pulling the original plate upward. Since the single particle film is already formed in a single layer state on the liquid surface of the lower layer liquid in the single particle film forming step, the temperature condition of the transfer step (the temperature of the lower layer liquid) and the pulling speed of the original plate are somewhat Even if it fluctuates, there is no fear that the single particle film collapses and becomes multilayered in the transfer step.
  • the temperature of the lower layer liquid is usually about 3 to 30 ° C., depending on the environmental temperature which fluctuates depending on the season and the weather.
  • an LB trough apparatus including a surface pressure sensor based on a Wilhelmy plate or the like for measuring the surface pressure of a single particle film as a water tank and a movable barrier for compressing the single particle film in the direction along the liquid surface.
  • the single particle film can be compressed to a preferable diffusion pressure (density) while measuring the surface pressure of the single particle film, and can be moved at a constant speed toward the substrate. .
  • the preferred diffusion pressure is 5 to 80 mNm -1 , more preferably 3 to 40 mNm -1 . With such a diffusion pressure, it is easy to obtain a single particle film in which each particle is densely packed two-dimensionally.
  • the speed of pulling up the original plate is preferably 0.5 to 20 mm / min.
  • the LB trough apparatus can be obtained as a commercial product.
  • the metal alkoxide exemplified as the hydrophobizing agent a general organic binder, an inorganic binder and the like can be used.
  • the amount of binder used is preferably 0.001 to 0.02 mass times the mass of the single particle film. In such a range, the particles can be sufficiently fixed without causing a problem that the binder is too much and the binder is clogged between particles, which adversely affects the accuracy of the single particle film.
  • the binder solution may be removed by using a spin coater or tilting the original plate after the binder solution has penetrated. After the binder solution has penetrated, heat treatment may be appropriately performed according to the type of the binder. When a metal alkoxide is used as a binder, heat treatment is preferably performed at 40 to 80 ° C. for 3 to 60 minutes.
  • the original plate on which the single particle film is formed may be heated to fuse the particles constituting the single particle film to the original plate.
  • the heating temperature may be determined according to the material of the particles and the material of the original plate. In the case of particles having a particle diameter of 1 ⁇ m or less, the interfacial reaction is initiated at a temperature lower than the melting point inherent to the material constituting the particles, so sintering is completed at a relatively low temperature side.
  • the heating temperature is too high, the fused area of the particles becomes large, and as a result, the shape of the single particle film may be changed, which may affect the accuracy.
  • the heating is performed in air, depending on the material, the original plate and the particles may be oxidized.
  • a thermally oxidized layer is formed on the surface of this substrate with a thickness of about 200 nm. Therefore, in the dry etching process described later, it is necessary to set the etching conditions in consideration of the possibility of such oxidation.
  • the original plate is dry etched using the single particle film as an etching mask under the condition that both the particles and the original plate are substantially etched.
  • each particle constituting the single particle film is etched, the particle diameter of each particle gradually decreases, and a gap is also formed in a portion where the particles are in contact with each other before dry etching.
  • the particles are formed, and the particles are not in contact with each other.
  • the etching gas passes through the gaps between the particles to reach the surface of the original plate, and the surface of the original plate located below the gaps is etched to form a recess.
  • the part covered with particles remains unetched, and this part becomes the convex 3c. Thereby, the substrate 1 is obtained.
  • the particles may be dry etched under conditions that the original plate is not substantially etched.
  • the thickness of the convex portion 3c (occupied volume in surface layer: filling factor), convex portion 3c Height (the depth of the recess) etc. can be adjusted.
  • the etching gas can be appropriately selected from known etching gases according to the material of the particles, the substrate, etc., so that both the particles and the original plate can be etched.
  • the original plate is glass and the particles are silica (SiO 2 )
  • the original plate is quartz and the particles are silica
  • Ar or CF 4 can be used.
  • Cl 2 , BCl 3 , SiCl 4 , HBr, HI, HCl, etc. can be used.
  • the etching gas may be used alone or in combination of two or more. Adjustment of etching conditions is facilitated by the mixing ratio of two or more etching gases.
  • the etching gas may be diluted with a gas other than the etching gas.
  • the dry etching is preferably performed by anisotropic etching in which the etching rate in the vertical direction is larger than in the horizontal direction of the original plate.
  • anisotropic etching such as a reactive ion etching apparatus, an ion beam etching apparatus, etc., and generate a bias electric field of about 20 W at the minimum, it is possible to generate plasma
  • There are no particular limitations on specifications such as the method, the structure of the electrode, the structure of the chamber, and the frequency of the high frequency power source.
  • the etching selectivity in dry etching is not particularly limited, and each condition of etching (material of particles constituting single particle film, material of original plate, type of etching gas, The bias power, antenna power, gas flow rate, pressure, etching time, etc. can be adjusted.
  • the dry etching of the original plate may be ended when the particles constituting the single particle film disappear, or may be ended before the particles disappear.
  • the particles remaining on the formed substrate 1 are removed after the dry etching of the original plate.
  • the method for removing particles include a chemical removal method using an etchant which is etchable to particles and etch resistant to the substrate 1, and a physical removal method using a brush roll cleaner or the like.
  • the original plate is obtained as described above.
  • the transferred product of the original plate is obtained by transferring the two-dimensional lattice structure of the original plate surface to another original plate one or more times.
  • a transfer product having a two-dimensional lattice structure in which the two-dimensional lattice structure of the original plate surface is inverted is obtained.
  • a transfer product having a two-dimensional lattice structure similar in shape to the two-dimensional lattice structure of the original plate surface is obtained.
  • the two-dimensional lattice structure of the original plate surface is transferred to a mold (a mold or a stamper) (first transfer), and then the two-dimensional lattice structure of the mold is transferred (second transfer).
  • a transfer product having a two-dimensional lattice structure of the same shape as the two-dimensional lattice structure is obtained.
  • an electroforming method as disclosed in JP 2009-158478 A is preferable.
  • Examples of a method for transferring a two-dimensional lattice structure of a mold include a nanoimprinting method, a heat pressing method, an injection molding method, a UV embossing method, and the like as disclosed in JP-A-2009-158478. Above all, the nanoimprint method is suitable for the transfer of a fine two-dimensional lattice structure.
  • the analysis substrate 10 is also excellent in productivity.
  • metal can be deposited on the substrate 1B, and further, the metal nanoparticle dispersion can be coated and dried.
  • the analytical substrate 10 is useful for optical analysis utilizing electric field enhancement by surface plasmon resonance. As such an optical analysis method, the same as described above can be mentioned.
  • the analysis substrate 10 is useful for optical analysis utilizing an electric field enhancement effect by surface plasmon resonance.
  • optical analysis include Raman spectroscopy, infrared spectroscopy, and fluorescence analysis.
  • Raman spectroscopy is preferable.
  • the Raman spectroscopy is an analysis means for observing the Raman scattering shifted by the vibrational energy of the molecule with respect to the incident light when the sample is irradiated with light, and analyzing the structure at the molecular level.
  • the obtained Raman spectrum is a vibration spectrum based on the vibration of the molecule, the vertical axis is the scattering intensity (Intensity), and the horizontal axis is the Raman shift (cm ⁇ 1 ) Is represented by
  • the vibration mode of the same functional group is detected in the same wave number in the Raman spectroscopy and the infrared spectroscopy, but unlike the infrared spectroscopy, the Raman spectroscopy can measure the aqueous sample, so the living body It has the advantage of not requiring pretreatment of the sample in analysis of the sample, food sample, etc.
  • Raman spectroscopy without surface electric field enhancement has the disadvantage that the intensity of the Raman scattered light is very low.
  • Surface enhanced Raman spectroscopy is Raman spectroscopy using SERS.
  • the Raman scattering (Stokes scattering and anti-Stokes scattering) intensity of the molecules adsorbed on the surface of the analysis substrate 10 can be significantly enhanced by the SERS effect, which enables high sensitivity spectral analysis. .
  • SERS Raman scattering
  • even in the case of a dilute trace sample it is possible to detect a spectrum unique to a substance, which is useful for environmental measurement, measurement of a trace biomarker, detection of a biological or chemical weapon, and the like.
  • FIG. 4 shows an example in which the shape of the non-film formation region G in a top view is a band shape, but the shape of the non-film formation region G in a top view is not limited thereto. For example, it may have a circular shape, a rectangular shape, a tree shape, or an irregular shape.
  • the shape, size, and distribution of each of the plurality of non-film formation regions G are random (not constant), the shape and size of each of the plurality of non-film formation regions G may be constant.
  • the plurality of non-film formation regions G may be regularly arranged.
  • FIG. 5 shows an example in which the metal surface 3 a surrounding the non-film formation region G is an inclined surface, the metal surface 3 a may be a non-inclined surface.
  • the metal surface 3a may be a smooth surface or an uneven surface.
  • the metal film is a metal film formed by a method of depositing metal on the first surface of the substrate (sputtering method, vacuum evaporation method, etc.)
  • the metal surface surrounding the non-film formation region G is locally inclined In many cases, it is an irregular surface.
  • the gap in the minor axis direction of the non-film formation region G is called a nanogap.
  • Measurement gaps in the nanogap first two arguments diagonal L D in the SEM image obtained as described above, all the non-deposition region G moiety regard measuring the gap width in the minor axis direction of the diagonal lines Do.
  • the length measurement is performed at the intersection where the diagonal intersects each non-film formation region G. Specifically, a point P which is a half of the intersection distance formed by the diagonal with the non-film formation region G is defined.
  • the thickness of the metal film 3 was measured by the above-mentioned method. That is, a very thin scratch (scratch) is made with a sharp knife tip to the metal film 3 deposited on the substrate, and the area including the scratch is measured by a stylus-type step meter (fine shape measuring machine ET4000A
  • the average thickness of the metal film 3 was measured by a method of measuring the average height difference between the bottom surface of the flaw (where the substrate is exposed) and the surface of the metal film 3 by the Kosaka Research Institute, Ltd. .
  • a stylus type step system is used, but an atomic force microscope (AFM) image is obtained to similarly average the difference in height between the exposed portion of the substrate and the surface of the metal film 3 The same result can be obtained even if it is determined.
  • AFM atomic force microscope
  • the above-mentioned hydrophobized particle slurry was dropped onto the water surface of the lower layer water of pH 7.2 at 21 ° C. to form a particle monolayer film on the water surface. Furthermore, while compressing the particle monolayer film with the barrier, the clean flat quartz substrate previously immersed in water is gradually pulled up at 5 mm / min, and the particle monolayer film on the water surface is transferred onto the quartz substrate.
  • the Au thin film was pressured on the periodic uneven structure at a pressure of 6 to 8 Pa, a current value of 15 mA, and a deposition rate of 11.6 nm / min. The film was formed to a thickness of 8 nm.
  • the step of spray coating an Au nanoparticle dispersion (average primary particle diameter: 20.7 nm) on an Au thin film and drying was repeated three times to disperse and arrange Au nanoparticles on the substrate.
  • FIG. 6 shows an SEM image of the obtained analysis substrate.
  • the above-mentioned hydrophobized particle slurry was dropped onto the water surface of the lower layer water of pH 7.2 at 21 ° C. to form a particle monolayer film on the water surface. Furthermore, while compressing the particle monolayer film with the barrier, the clean flat quartz substrate previously immersed in water is gradually pulled up at 5 mm / min, and the particle monolayer film on the water surface is transferred onto the quartz substrate.
  • an Au thin film was pressured on the periodic uneven structure at a pressure of 6 to 8 Pa, a current value of 15 mA, and a deposition rate of 11.6 nm / min. The film was formed to a thickness of 0 nm.
  • the step of spray coating an Au nanoparticle dispersion (average primary particle diameter: 20.7 nm) on an Au thin film and drying was repeated three times to disperse and arrange Au nanoparticles on the substrate.
  • FIG. 7 shows an SEM image of the obtained analysis substrate.
  • the clean flat quartz substrate previously immersed in water is gradually pulled up at 5 mm / min, and the particle monolayer film on the water surface is transferred onto the quartz substrate.
  • an Au thin film is formed at a pressure of 6 to 8 Pa, a current value of 15 mA, and a deposition rate of 11.6 nm / min.
  • the film was formed to a thickness of 2 nm.
  • the Raman scattering intensity was measured using the analysis substrates of Examples 1 to 2 and Comparative Examples 1 to 3. The results are shown in Table 1.
  • the analysis substrates of Comparative Example 1 and Comparative Example 2 could not detect Raman scattering.
  • the Raman scattering could be detected in the substrate for analysis of Comparative Example 3, its intensity was lower than the intensities of all the examples.
  • Raman scattering at a sample concentration of 100 ⁇ M was obtained at high intensity, and Raman scattering could be detected even at a sample concentration as low as 1 nM.

Abstract

This analysis substrate (10) comprises: a substrate (1) having at least a first surface (1a) that comprises a dielectric or a conductor and having a two-dimensional lattice structure that has a plurality of recessed sections or protruding sections periodically arranged two dimensionally on the first surface (1a); a metal membrane (3) provided upon the first surface (1a) of the substrate (1) and having a surface sheet resistance at 25°C of no more than 5,000 Ω/□; and a plurality of metal nanoparticles (5) arranged dispersed upon the metal membrane (3) and having an average primary particle diameter of 5–100 nm.

Description

分析用基板Analytical substrate
　本発明は、分析用基板に関する。
　本願は、２０１８年１月２５日に、日本に出願された特願２０１８－０１０６８３号に基づき優先権を主張し、その内容をここに援用する。 The present invention relates to a substrate for analysis.
Priority is claimed on Japanese Patent Application No. 2018-010683, filed January 25, 2018, the content of which is incorporated herein by reference.
　従来、ラマン分光法は、ラマン散乱光の強度が非常に弱いことが問題とされていた。その改善のために表面増強ラマン散乱（Surface Enhanced Raman Scattering：ＳＥＲＳ）を利用することが検討されている。ＳＥＲＳは、Ａｕ、Ａｇ等の金属表面において、表面プラズモン共鳴による電場増強で、吸着した測定対象分子のラマン散乱光の強度が著しく増強される現象である。ラマン分光法以外の赤外吸収分光法や蛍光分光法における光学的分析法においても表面プラズモン共鳴による電場増強を利用することが検討されている。 Conventionally, it has been considered that Raman spectroscopy has a very low intensity of Raman scattered light. It is considered to use surface enhanced Raman scattering (SERS) for the improvement. SERS is a phenomenon in which the intensity of Raman scattered light of a molecule to be measured adsorbed is significantly enhanced by the electric field enhancement by surface plasmon resonance on a metal surface such as Au or Ag. The use of electric field enhancement by surface plasmon resonance is also considered in optical analysis methods other than Raman spectroscopy and infrared absorption spectroscopy and fluorescence spectroscopy.
　表面プラズモン共鳴による電場増強を利用する分析用基板として、例えば以下のものが提案されている。
　（１）複数のくぼみ又は複数の突起が予め定められた特定の格子間隔で格子状に配置されて、表面プラズモン共鳴を生ずるナノ周期構造を有する基板と、前記ナノ周期構造の表面に形成された金属皮膜とを備えるラマン分光分析用信号増幅装置（特許文献１）。
　（２）金属層と、前記金属層上に設けられた誘電体層と、前記誘電体層上に設けられた複数の金属粒子とを含む電場増強素子であって、複数の前記金属粒子は、前記金属層と前記誘電体層との界面を伝播する伝搬型表面プラズモンを励起可能な周期配列を有し、前記伝搬型表面プラズモンと、前記金属粒子に励起される局在型表面プラズモンとは電磁的に相互作用し、各表面プラズモンの共鳴波長は異なり、前記電場増強素子に白色光を照射したときの反射光のスペクトルにおいて第１吸収領域、第２吸収領域の半値幅が特定の関係を満たし、前記電場増強素子の励起光の波長が前記第２吸収領域の範囲に含まれる電場増強素子（特許文献２）。 For example, the followings have been proposed as analytical substrates utilizing electric field enhancement by surface plasmon resonance.
(1) A substrate having a nanoperiodic structure in which a plurality of depressions or a plurality of projections are arranged in a lattice at a predetermined specific lattice spacing to generate surface plasmon resonance, and formed on the surface of the nanoperiodic structure The signal amplification apparatus for Raman spectroscopy analysis provided with a metal film (patent document 1).
(2) An electric field enhancing element including a metal layer, a dielectric layer provided on the metal layer, and a plurality of metal particles provided on the dielectric layer, wherein the plurality of metal particles are It has a periodic arrangement capable of exciting propagating surface plasmons propagating through the interface between the metal layer and the dielectric layer, and the propagating surface plasmons and localized surface plasmons excited by the metal particles are electromagnetic. Interact with each other, and the resonance wavelength of each surface plasmon is different, and in the spectrum of the reflected light when the electric field enhancing element is irradiated with white light, the half bandwidths of the first absorption region and the second absorption region satisfy a specific relationship. An electric field enhancing element in which the wavelength of excitation light of the electric field enhancing element is included in the range of the second absorption region (Patent Document 2).
特開２０１５－２３２５２６号公報JP, 2015-232526, A 特開２０１５－２１２６２６号公報JP, 2015-212626, A
　しかし、（１）～（２）の分析用基板は、感度が充分ではない場合がある。
　特許文献１の装置については、伝搬型表面プラズモンを利用しているので、ナノ周期構造上の電場分布のばらつきが少ないという長所はあるが、電場増強が伝搬型表面プラズモンのみに拠るため、増強効果が低いという短所がある。
　一方、特許文献２の電場増強素子については、伝搬型表面プラズモンと局在型表面プラズモンを組み合わせ、電場分布の均一化を伝搬型表面プラズモンで行い、電場強度を高めることを局在型表面プラズモンで行うことで、伝搬型と局在型の長所を掛け合わせる構成であり、均一性と強度の両立がある程度可能となっている。しかし、金属層と金属粒子の間に誘電体層が存在することから、検体の測定対象分子は伝搬型表面プラズモンの電場増強効果の最も高い金属膜表面に接近することができないという短所がある。また、伝搬型表面プラズモンを励起するために必要な配置で金属粒子が配置されるため、局在型表面プラズモンとして効果の大きな金属粒子間の間隙を利用した電場増強を利用するには粒子間距離が大きすぎるのも短所として挙げられる。 However, the analysis substrates of (1) to (2) may not have sufficient sensitivity.
The device of Patent Document 1 utilizes propagating surface plasmons, and thus has the advantage that the variation of the electric field distribution on the nano-periodic structure is small, but the enhancement effect is due to the electric field enhancement solely by the propagating surface plasmons. Has the disadvantage of being low.
On the other hand, in the electric field enhancing element of Patent Document 2, the propagating surface plasmon and the localized surface plasmon are combined, the electric field distribution is homogenized by the propagating surface plasmon, and the localized electric surface plasmon is enhanced. By doing this, it is a configuration that combines the advantages of the propagation type and the localized type, and it is possible to achieve both uniformity and strength to some extent. However, due to the presence of the dielectric layer between the metal layer and the metal particles, there is a disadvantage that the molecule to be measured of the sample can not approach the metal film surface with the highest electric field enhancing effect of the propagating surface plasmon. In addition, since the metal particles are arranged in the arrangement necessary for exciting the propagating surface plasmon, the distance between the particles is required to utilize the electric field enhancement utilizing the gap between the metal particles having a large effect as the localized surface plasmon. Too large is also mentioned as a disadvantage.
　本発明は、表面プラズモン共鳴による電場増強を利用した光学的分析を高感度に実施できる分析用基板を提供することを目的とする。 An object of the present invention is to provide a substrate for analysis which can carry out optical analysis with high sensitivity utilizing electric field enhancement by surface plasmon resonance.
　本発明は、以下の態様を有する。
　〔１〕少なくとも第一面が誘電体または半導体からなり、前記第一面に、複数の凹部または凸部が周期的に二次元に配列した二次元格子構造を有する基板と、
　前記基板の第一面上に設けられた、２５℃における表面のシート抵抗が５０００Ω／□以下である金属膜と、
　前記金属膜上に分散配置された、平均一次粒子径が５～１００ｎｍである複数の金属ナノ粒子と、
を備える、分析用基板。
　〔２〕前記二次元格子構造が、三角格子構造または正方格子構造である、〔１〕の分析用基板。
　〔３〕前記金属膜が、前記金属膜内に長軸方向の長さが１μｍ以下の島状の隙間形状として設けられた、金属が存在せず前記基板の第一面が露出している複数の非成膜領域を有する、〔１〕または〔２〕の分析用基板。 The present invention has the following aspects.
[1] A substrate having a two-dimensional lattice structure in which at least a first surface is made of a dielectric or a semiconductor, and a plurality of recesses or projections are periodically arranged in two dimensions on the first surface,
A metal film provided on the first surface of the substrate and having a surface sheet resistance at 25 ° C. of 5000 Ω / □ or less;
A plurality of metal nanoparticles dispersed on the metal film and having an average primary particle diameter of 5 to 100 nm;
An analytical substrate comprising:
[2] The analytical substrate of [1], wherein the two-dimensional lattice structure is a triangular lattice structure or a square lattice structure.
[3] A plurality of the metal films are provided in the form of island-like gaps having a length of 1 μm or less in the major axis direction in the metal film, and a plurality of metal is not present and the first surface of the substrate is exposed The analytical substrate of [1] or [2], which has a non-film formation region of
　本発明によれば、表面プラズモン共鳴による電場増強を利用した光学的分析を高感度に実施できる分析用基板を提供できる。
　特に、特許文献２との明確な差異は、本発明においては検体の測定対象分子が伝搬型表面プラズモンの電場増強効果の最も高い金属膜表面に接近することができる点にある。この差異のため本発明は、従来技術よりもラマン散乱光の増強効果に優れる。 According to the present invention, it is possible to provide an analytical substrate capable of highly sensitively performing optical analysis utilizing electric field enhancement by surface plasmon resonance.
In particular, the clear difference from Patent Document 2 is that, in the present invention, the measurement target molecule of the sample can approach the metal film surface with the highest electric field enhancing effect of the propagating surface plasmon. Because of this difference, the present invention is superior to the prior art in the enhancement effect of Raman scattered light.
本発明の一実施形態の分析用基板を模式的に示す断面図である。It is a sectional view showing typically the substrate for analysis of one embodiment of the present invention. 図１に示す実施形態の一例に係る分析用基板を模式的に示す上面図である（ただし金属ナノ粒子の図示は省略した。）。It is an upper side figure which shows typically the board | substrate for analysis which concerns on an example of embodiment shown in FIG. 1 (however, illustration of the metal nanoparticle was abbreviate | omitted). 図２に示す分析用基板の斜視図である。It is a perspective view of the substrate for analysis shown in FIG. 図１に示す実施形態の一例に係る分析用基板の金属膜側の表面を模式的に示す拡大上面図である（ただし金属ナノ粒子の図示は省略した。）。It is an enlarged top view which shows typically the surface by the side of the metal film of the board | substrate for analysis which concerns on an example of embodiment shown in FIG. 1 (however, illustration of a metal nanoparticle was abbreviate | omitted). 図４におけるＩＶ－ＩＶ断面を模式的に示す部分断面図である（ただし金属ナノ粒子の図示は省略した。）。FIG. 5 is a partial cross-sectional view schematically showing a IV-IV cross-section in FIG. 4 (however, illustration of metal nanoparticles is omitted). 実施例１で得られた分析用基板の走査型電子顕微鏡像である。It is a scanning electron microscope image of the board | substrate for analysis obtained in Example 1. FIG. 実施例２で得られた分析用基板の走査型電子顕微鏡像である。7 is a scanning electron microscope image of the analysis substrate obtained in Example 2.
　以下、本発明の分析用基板について、添付の図面を参照し、実施形態を示して説明する。
　図１は、本発明の第一実施形態の分析用基板を模式的に示す断面図である。図２は、本実施形態の一例に係る分析用基板を模式的に示す上面図である。図３は、図２に示す分析用基板の斜視図である。ただし、図２～３においては、金属ナノ粒子の図示は省略した。
　本実施形態の分析用基板１０は、基板１と、基板１の第一面１ａ上に設けられた金属膜３と、金属膜３上に分散配置された複数の金属ナノ粒子５とを備える。
　基板１の第一面１ａは二次元格子構造を有する。金属膜３は第一面１ａに沿って形成されている。このため、第一面１ａ上に設けられた金属膜３の表面も二次元格子構造を有するものとなっている。
　金属膜３と複数の金属ナノ粒子５とは接している。 Hereinafter, an analysis substrate of the present invention will be described by showing an embodiment with reference to the attached drawings.
FIG. 1 is a cross-sectional view schematically showing an analysis substrate according to a first embodiment of the present invention. FIG. 2 is a top view schematically showing an analysis substrate according to an example of the present embodiment. FIG. 3 is a perspective view of the analysis substrate shown in FIG. However, the illustration of the metal nanoparticles is omitted in FIGS.
The analysis substrate 10 of the present embodiment includes a substrate 1, a metal film 3 provided on the first surface 1 a of the substrate 1, and a plurality of metal nanoparticles 5 dispersed on the metal film 3.
The first surface 1a of the substrate 1 has a two-dimensional lattice structure. The metal film 3 is formed along the first surface 1a. Therefore, the surface of the metal film 3 provided on the first surface 1a also has a two-dimensional lattice structure.
The metal film 3 and the plurality of metal nanoparticles 5 are in contact with each other.
（基板）
　基板１は、少なくとも第一面１ａが誘電体または半導体からなる。
　基板１としては、例えば、誘電体または半導体からなる基板であってもよく、第一面が誘電体または半導体となるように導電体層、誘電体層、半導体層のうち２層以上が積層された多層基板であってもよい。誘電体または半導体としては特に限定されず、分析用基板等の用途において公知の材質であってよい。
　基板１としては、典型的には、誘電体または半導体のみからなる基板が用いられ、例えば石英基板、アルカリガラスや無アルカリガラス等の各種ガラス基板、サファイア基板、シリコン（Ｓｉ）基板、シリコンカーバイド（ＳｉＣ）等の無機物質からなる基板、ポリメチルメタクリレート、ポリカーボネート、ポリスチレン、ポリオレフィン樹脂、ポリエステル樹脂等の有機物質からなる基板等が挙げられる。
　基板１の厚さは、特に限定されず、例えば０．１～５．０ｍｍであってよい。
　基板１の厚さは、ＪＩＳ　Ｂ７５０７に制定されている一般的なノギスによる測長方法により測定される。 (substrate)
At least the first surface 1a of the substrate 1 is made of a dielectric or a semiconductor.
The substrate 1 may be, for example, a substrate made of a dielectric or a semiconductor, and two or more of the conductor layer, the dielectric layer, and the semiconductor layer may be stacked such that the first surface is a dielectric or a semiconductor. It may be a multilayer substrate. The dielectric or semiconductor is not particularly limited, and may be a known material in applications such as a substrate for analysis.
Typically, a substrate made of only a dielectric or a semiconductor is used as the substrate 1 and, for example, a quartz substrate, various glass substrates such as alkali glass and non-alkali glass, sapphire substrate, silicon (Si) substrate, silicon carbide Examples include substrates made of inorganic substances such as SiC), and substrates made of organic substances such as polymethyl methacrylate, polycarbonate, polystyrene, polyolefin resin, and polyester resin.
The thickness of the substrate 1 is not particularly limited, and may be, for example, 0.1 to 5.0 mm.
The thickness of the substrate 1 is measured by a general caliper measurement method established in JIS B7507.
　第一面１ａの二次元格子構造は、金属膜３の表面に二次元格子構造を設けるためのものであり、金属膜３の表面の所望の二次元格子構造に応じて設定される。 The two-dimensional lattice structure of the first surface 1 a is for providing a two-dimensional lattice structure on the surface of the metal film 3, and is set according to the desired two-dimensional lattice structure on the surface of the metal film 3.
（金属膜）
　金属膜３を構成する金属としては、表面プラズモン共鳴による電場増強を発生させ得るものであればよく、例えば金、銀、アルミニウム、銅、白金、これらの２種以上の合金等が挙げられる。 (Metal film)
The metal constituting the metal film 3 may be any metal that can generate electric field enhancement by surface plasmon resonance, and examples thereof include gold, silver, aluminum, copper, platinum, alloys of two or more of these, and the like.
　金属膜３の２５℃における表面のシート抵抗（以下、「２５℃における表面のシート抵抗」を、単に「表面のシート抵抗」という場合がある。）は、５０００Ω／□以下であり、３～５０００Ω／□が好ましく、３～５００Ω／□がより好ましく、３～３００Ω／□が最も好ましい。金属膜３の表面のシート抵抗が前記上限値以下であることは、金属膜３が連続膜であることを示す。金属膜３の表面のシート抵抗がこの範囲内にある場合、金属膜３は、後述する非成膜領域Ｇによるナノギャップを持っていても、完全には分断されていない。また、金属膜３が非成膜領域Ｇを有する場合、金属膜３の表面のシート抵抗が前記上限値以下であることは、非成膜領域Ｇを介して対向する金属表面３ａ間の距離が、１～２０ｎｍの範囲に、より限定的には１～１０ｎｍの範囲に、さらに限定的には１～５ｎｍの範囲に入ることを意味する。金属膜３が不連続な膜（例えば島状に分散配置された複数の金属膜から構成されるもの）である場合、表面のシート抵抗は５０００Ω／□以下とはならない。金属膜３が部分的に非成膜領域Ｇを有していたとしても全体としては連続膜であることで、後述する伝搬型表面プラズモンを金属膜３が誘起することが可能となり、表面電場の重ね合わせによる非線形光学効果を得やすくなる。
　金属膜３の表面のシート抵抗（Ω／□）は、２５℃における値である。具体的には、２５℃の条件下で金属膜３の表面の任意の大きさの正方形の領域を電流が片方の端から対向する端へ流れる際の電気抵抗値（Ω）がシート抵抗である。詳しくは後述する実施例に示すとおりである。 The sheet resistance of the surface of the metal film 3 at 25 ° C. (hereinafter, “sheet resistance of the surface at 25 ° C.” may simply be referred to as “sheet resistance of the surface”) is 5000 Ω / □ or less, and 3 to 5000 Ω. / □ is preferable, 3 to 500 Ω / □ is more preferable, and 3 to 300 Ω / □ is the most preferable. The sheet resistance of the surface of the metal film 3 being equal to or less than the upper limit value indicates that the metal film 3 is a continuous film. When the sheet resistance of the surface of the metal film 3 is within this range, the metal film 3 is not completely divided even though it has nanogaps due to the non-film formation region G described later. When the metal film 3 has the non-film formation region G, the sheet resistance of the surface of the metal film 3 is less than or equal to the above upper limit value because the distance between the metal surfaces 3 a facing each other via the non-film formation region G is In the range of 1 to 20 nm, more specifically in the range of 1 to 10 nm, and more specifically in the range of 1 to 5 nm. When the metal film 3 is a discontinuous film (for example, one composed of a plurality of metal films dispersed in an island shape), the sheet resistance of the surface does not become 5000 Ω / □ or less. Even if the metal film 3 partially has the non-film formation region G, the metal film 3 can induce propagation type surface plasmons, which will be described later, because the film is a continuous film as a whole. It becomes easy to obtain the nonlinear optical effect by superposition.
The sheet resistance (Ω / □) of the surface of the metal film 3 is a value at 25 ° C. Specifically, the sheet resistance is the electrical resistance (Ω) when current flows from one end to the opposite end of a square area of any size on the surface of the metal film 3 under the condition of 25 ° C. . The details are as shown in Examples described later.
　金属膜３は、基板１の第一面１ａに追従する二次元格子構造を有する。
　ここで「追従する」とは、金属膜３表面の二次元格子構造における凸部又は凹部の位置が、基板１の第一面１ａの二次元格子構造における凸部又は凹部の位置と略一致することを示す。 The metal film 3 has a two-dimensional lattice structure that follows the first surface 1 a of the substrate 1.
Here, “follow” means that the position of the convex portion or the concave portion in the two-dimensional lattice structure on the surface of the metal film 3 substantially coincides with the position of the convex portion or the concave portion in the two-dimensional lattice structure of the first surface 1 a of the substrate 1 Indicates that.
　連続膜である金属膜３の表面が二次元格子構造を有することで、金属膜３の表面で伝搬型表面プラズモン共鳴による電場増強を発生させることができる。
　ここで、「二次元格子構造」とは、複数の凸部又は凹部が周期的に二次元に配列した周期的凹凸構造である。二次元に配列とは、複数の凸部又は凹部配列方向が２方向以上であることを示す。
　なお、複数の凸部又は凹部が周期的に一次元に配列した周期的凹凸構造を一次元格子構造ともいう。一次元に配列とは、複数の凸部又は凹部の配列方向が１方向であることを示す。
　金属表面の伝搬型表面プラズモンは、金属表面に入射した光（ラマン分光法で用いられるレーザー等の励起光）により生じる自由電子の疎密波が表面電磁場を伴うものである。金属表面が平坦である場合、金属表面に存在する表面プラズモンの分散曲線と光の分散直線とは交差しないため、伝搬型表面プラズモン共鳴は誘発されない。金属表面に周期的凹凸構造があると、この周期的凹凸構造によって回折された光（回折光）の分散直線が表面プラズモンの分散曲線と交差するようになり、伝搬型表面プラズモン共鳴が誘発される。
　周期的凹凸構造における複数の凸部又は凹部の配列方向が多い方が、回折光が得られる条件が多く、高効率で伝搬型表面プラズモン共鳴を誘発できる。周期的凹凸構造として二次元格子構造を有することで、周期的凹凸構造が一次元格子構造（例えば複数の溝（凹部）又は凸条（凸部）が平行に配置されたラインアンドスペース構造）である場合に比べて、表面プラズモン共鳴による電場増強を利用した光学的分析をより高感度に実施できる。 When the surface of the metal film 3 which is a continuous film has a two-dimensional lattice structure, electric field enhancement can be generated on the surface of the metal film 3 by propagating surface plasmon resonance.
Here, the “two-dimensional lattice structure” is a periodic uneven structure in which a plurality of convex portions or concave portions are periodically arranged in two dimensions. Two-dimensionally arranged indicates that the plurality of convex portions or concave portions are arranged in two or more directions.
Note that a periodic uneven structure in which a plurality of projections or depressions are periodically arranged in one dimension is also referred to as a one-dimensional lattice structure. The arrangement in one dimension indicates that the arrangement direction of the plurality of projections or depressions is one direction.
The propagation type surface plasmon of the metal surface is a surface electromagnetic field accompanied by a compressional wave of free electrons generated by light (excitation light such as a laser used in Raman spectroscopy) incident on the metal surface. When the metal surface is flat, propagating surface plasmon resonance is not induced because the dispersion curve of the surface plasmon present on the metal surface does not cross the dispersion line of light. When a periodic uneven structure exists on the metal surface, the dispersion straight line of light (diffracted light) diffracted by this periodic uneven structure intersects with the dispersion curve of the surface plasmon, and the propagating surface plasmon resonance is induced .
As the arrangement direction of the plurality of convex portions or concave portions in the periodic concavo-convex structure is larger, there are more conditions under which diffracted light can be obtained, and propagation surface plasmon resonance can be induced with high efficiency. By having a two-dimensional lattice structure as a periodic uneven structure, the periodic uneven structure is a one-dimensional lattice structure (for example, a line and space structure in which a plurality of grooves (concave portions) or convex lines (convex portions) are arranged in parallel). Optical analysis using electric field enhancement by surface plasmon resonance can be performed more sensitively than in some cases.
　好ましい二次元格子構造としては、配列方向が２方向で、その交差角度が９０°である正方格子構造、配列方向が３方向で、その交差角度が６０°である三角格子（六方格子ともいう。）構造等が挙げられる。二次元格子構造を構成する凸部の形状は、例えば円柱形状、円錐形状、円錐台形状、正弦波形状、半球体形状、略半球体形状、楕円体形状、或いはそれらを基本とした派生形状等であってよい。二次元格子構造を構成する凹部の形状は、例えば前記で挙げた凸部の形状が反転した形状であってよい。
　二次元格子構造としては、より高効率で伝搬型表面プラズモン共鳴を誘発できることから、三角格子構造が好ましい。 As a preferable two-dimensional lattice structure, a tetragonal lattice structure in which the arrangement direction is two directions and the crossing angle is 90 °, and the arrangement direction is three directions and the crossing angle is 60 ° (also referred to as a hexagonal lattice). And the like. The shape of the convex portion constituting the two-dimensional lattice structure is, for example, a cylindrical shape, a conical shape, a truncated cone shape, a sine wave shape, a hemispherical shape, a substantially hemispherical shape, an ellipsoidal shape, or a derivative shape based on them It may be. The shape of the concave portion constituting the two-dimensional lattice structure may be, for example, a shape obtained by inverting the shape of the convex portion mentioned above.
As a two-dimensional lattice structure, a triangular lattice structure is preferable because it can induce propagating surface plasmon resonance with higher efficiency.
　本実施形態の一例に係る金属膜３表面の二次元格子構造は、図２～３に示すように、複数の円錐台形状の凸部３ｃから構成された三角格子構造である。
　凸部３ｃの高さは、１５～１５０ｎｍが好ましく、３０～８０ｎｍがより好ましい。凸部３ｃの高さが前記範囲の下限値以上であれば、金属膜３表面の二次元格子構造が回折格子として充分に機能し、伝搬型表面プラズモン共鳴を誘発することができる。凸部３ｃの高さが前記範囲の上限値以下であれば、金属膜３が連続膜となりやすい。
　凸部３ｃが他の形状である場合にも、好ましい高さはおおよそ同様である。金属膜３表面の二次元格子構造が複数の凹部から構成される場合、この凹部の好ましい深さは、凸部３ｃの好ましい高さとおおよそ同様である。正確には、凸部３ｃの高さの最適値は、表面プラズモンによる電磁場と相互作用する凸部３ｃの体積分率や誘電率によって決定される。 The two-dimensional lattice structure of the surface of the metal film 3 according to an example of the present embodiment is a triangular lattice structure constituted of a plurality of truncated cone-shaped convex portions 3c as shown in FIGS.
The height of the convex portion 3c is preferably 15 to 150 nm, and more preferably 30 to 80 nm. If the height of the convex portion 3c is equal to or more than the lower limit value of the above range, the two-dimensional lattice structure on the surface of the metal film 3 sufficiently functions as a diffraction grating, and propagation type surface plasmon resonance can be induced. If the height of the convex portion 3c is equal to or less than the upper limit value of the above range, the metal film 3 tends to be a continuous film.
Also in the case where the convex portion 3c has another shape, the preferable height is approximately the same. When the two-dimensional lattice structure on the surface of the metal film 3 is composed of a plurality of recesses, the preferred depth of the recesses is approximately the same as the preferred height of the protrusions 3c. Precisely, the optimum value of the height of the convex portion 3c is determined by the volume fraction and the dielectric constant of the convex portion 3c which interacts with the electromagnetic field by the surface plasmon.
　凸部３ｃの高さは、隣接する３つの凸部から等距離にある中心点を起点として３つの凸部の円錐台の頂面の平均値までの垂直方向の距離をＡＦＭ（原子間力顕微鏡）等によって測長して求める。測長には、互いに１００μｍ以上離れた５箇所の二次元格子構造表面を用いる。これら５箇所の測定領域に関して５μｍ×５μｍのＡＦＭ像を取得し、それぞれのＡＦＭ像に関して無作為に抽出した９箇所の上記３点中心深さを測長する。ＡＦＭ探針はスキャン方向によって像に異方性が生じる場合があるため、測長は、図２に示すように、ＤＭ１～ＤＭ３の３方向にプロファイル像を作成し、それぞれの方向にて３箇所、合計９箇所の測長点にて行う。その９箇所の測長点で得られた測定値の平均値を１つの測定領域の測定値とし、同様に５つの測定領域の測定値を求め、さらにこの５つの測定領域の測定値の平均を求め、凸部３ｃの高さとする。
　ＤＭ１～ＤＭ３はそれぞれ、金属膜３の主面において、凸部３ｃの３つの配列方向ＥＭ１～ＥＭ３それぞれと略直交する方向である（実際の格子配列は多少歪みもあるため、必ず直交するとは限らない）。
　他の形状の凸部の高さや凹部の深さも同様の測定方法によって測定される。 The height of the convex portion 3c is the distance in the vertical direction to the average value of the top surfaces of the truncated cones of the three convex portions starting from the central point equidistant from the adjacent three convex portions as AFM (atomic force microscope Measured by) etc. For measurement, five two-dimensional lattice structure surfaces separated by 100 μm or more are used. AFM images of 5 μm × 5 μm are acquired for these five measurement regions, and the above-mentioned three-point center depths of nine locations randomly measured for each AFM image are measured. Since the AFM probe may generate anisotropy in the image depending on the scan direction, as shown in Fig. 2, the length measurement is performed by creating profile images in three directions D M1 to D M3 and in each direction Perform at three measurement points, for a total of nine measurement points. The average value of the measured values obtained at the nine measurement points is taken as the measured value of one measurement area, the measured values of the five measurement areas are similarly determined, and the average of the measured values of the five measurement areas is calculated. The height of the projection 3c is obtained.
Each of D M1 to D M3 is a direction substantially orthogonal to each of the three arrangement directions E M1 to E M3 of the convex portions 3 c on the main surface of the metal film 3 (Because the actual lattice arrangement has some distortion, Not necessarily orthogonal).
The heights of the projections of the other shapes and the depths of the recesses are also measured by the same measurement method.
　凸部３ｃの配列方向における凸部３ｃのピッチΛは、入射光（励起光）の波長λｉに対応して設計される。入射光の波数をｋｉ（ｋｉ＝２π/λｉ）、ｋｉにおける金属の比誘電率の実数部をε１、検体の比誘電率の実数部をε２、とすると、表面プラズモンの波数ｋｓｐｐは、下式１：
　　ｋｓｐｐ＝ｋｉ（（ε１×ε２）/（ε１＋ε２））０．５　　（式１）
で略式的に得られる。表面プラズモンの波長λｓｐｐはｋｓｐｐの逆数であり、凸部３ｃは三角格子配列であるから、凸部３ｃのピッチΛは、下式２：
　　Λ＝（２/√３）×λｓｐｐ　　（式２）
により求まる。式１および式２は一般的なものである。
　上記の計算法によれば、例えば入射光の波長λｉ＝７８５ｎｍ、凸部３ｃを構成する金属が金（Ａｕ）、検体が水溶液（ε２≒１．３３）であるとき、
　　ｋｓｐｐ＝１１．８μｍ－１、Λ＝６５５ｎｍ
となる。同様に、例えば入射光の波長λｉ＝６３３ｎｍ、凸部３ｃを構成する金属が金（Ａｕ）、検体が有機物乾燥体（ε２≒２．２５）であるとき、
　　ｋｓｐｐ＝１６．６μｍ－１、Λ＝４３８ｎｍ
である。入射光にレーザーを使用するとその波長分布は極めて狭いので、実質的に凸部３ｃは上記ピッチΛにできるだけ近く作製すればよい。また、２次元格子配列が正方格子の場合、或いは１次元格子配列（ライン＆スペース）の場合は、式２の代わりに下式３を用いればよい。
　　Λ＝λｓｐｐ　　（式３）
　入射光として用いるレーザー光源は、７８５、６３３、５３２、５１５、４８８、４７０ｎｍ等、様々な波長に対応するものがある。一般に、海島構造、金属ナノ粒子、周期的凹凸構造を構成する金属種として、おおよそ５００ｎｍ台の波長より大きい光源には金（Ａｕ）を用いるのが好ましく、おおよそ５００ｎｍ台の波長より小さい光源には銀（Ａｇ）を用いるのが好ましいが、金（Ａｕ）、銀（Ａｇ）以外の金属種でも表面増強ラマン散乱効果を得られる場合があり、必ずしも上記の限りではない。
　凸部３ｃが他の形状である場合にも、好ましいピッチは同様である。金属膜３表面の二次元格子構造が複数の凹部から構成される場合、凹部の配列方向における凹部の好ましいピッチは、凸部３ｃの好ましいピッチと同様である。 The pitch Λ of the convex portions 3c in the arrangement direction of the convex portions 3c is designed to correspond to the wavelength λ i of the incident light (excitation light). Assuming that the wave number of the incident light is k i (k i = 2π / λ i ), the real part of the relative dielectric constant of metal at k i is ε 1 , and the real part of the relative dielectric constant of the specimen is ε 2 . The wavenumber k spp is given by the following equation 1:
k spp = k i ((ε 1 × ε 2) / (ε 1 + ε 2)) 0.5 ( Equation 1)
Can be obtained schematically. Since the wavelength λ spp of the surface plasmon is an inverse number of k spp and the convex portions 3 c have a triangular lattice arrangement, the pitch Λ of the convex portions 3 c is expressed by the following equation 2:
Λ = (2 / √3) × λ spp (Expression 2)
Determined by Formula 1 and Formula 2 are general.
According to the above calculation method, for example, when the wavelength λ i of incident light is 785 nm, the metal constituting the convex portion 3c is gold (Au), and the sample is an aqueous solution (ε 2 1.31.33),
k spp = 11.8 μm −1 , Λ = 655 nm
It becomes. Similarly, for example, when the wavelength λ i of incident light is 633 nm, the metal forming the convex portion 3c is gold (Au), and the sample is a dried organic substance (ε 2 2.22.25),
k spp = 16.6 μm −1 , Λ = 438 nm
It is. When a laser is used for incident light, its wavelength distribution is extremely narrow, and therefore, the convex portions 3c may be fabricated as close as possible to the pitch Λ. When the two-dimensional lattice arrangement is a square lattice or one-dimensional lattice arrangement (line and space), the following equation 3 may be used instead of the equation 2.
Λ = λ spp (Equation 3)
Laser light sources used as incident light include ones corresponding to various wavelengths such as 785, 633, 532, 515, 488, and 470 nm. Generally, it is preferable to use gold (Au) for a light source larger than the wavelength of about 500 nm, and a light source smaller than the wavelength about 500 nm or so as a metal species constituting the sea-island structure, metal nanoparticles and periodic uneven structure. It is preferable to use silver (Ag), but metal enhanced species other than gold (Au) and silver (Ag) may be able to obtain the surface enhanced Raman scattering effect, which is not necessarily limited to the above.
The preferred pitch is the same as in the case where the projections 3c have other shapes. When the two-dimensional lattice structure of the surface of the metal film 3 is composed of a plurality of recesses, the preferred pitch of the recesses in the arrangement direction of the recesses is the same as the preferred pitch of the protrusions 3c.
　凸部３ｃのピッチは、隣接する２つの円錐台突起の各中心点の水平方向の距離をＡＦＭ（原子間力顕微鏡）等によって測長して求める。測長には、互いに１００μｍ以上離れた５箇所の二次元格子構造表面を用いる。これら５箇所の測定領域に関して５μｍ×５μｍのＡＦＭ像を取得し、それぞれのＡＦＭ像に関して無作為に抽出した９箇所の上記２点間距離を測長する。ＡＦＭ探針はスキャン方向によって像に異方性が生じる場合があるため、測長は図２に示すように、ＥＭ１～ＥＭ３の３方向にプロファイル像を作成し、それぞれの方向にて３箇所、合計９箇所の測長点にて行う。その９箇所の測長点で得られた測定値の平均値を１箇所の測定領域の測定値とし、さらに５箇所の測定領域の測定値の平均を求め、凸部３ｃのピッチとする。
　他の形状の凸部のピッチや凹部のピッチも同様の測定方法によって測定される。 The pitch of the convex portions 3c is obtained by measuring the horizontal distance between the center points of two adjacent truncated conical projections by AFM (atomic force microscope) or the like. For measurement, five two-dimensional lattice structure surfaces separated by 100 μm or more are used. AFM images of 5 μm × 5 μm are acquired for these five measurement regions, and the distance between the two points of nine locations randomly extracted for each AFM image is measured. Since the AFM probe may cause anisotropy in the image depending on the scan direction, as shown in Fig. 2, the profile image is created in three directions E M1 to E M3 as shown in FIG. Perform at 9 points in total. The average value of the measurement values obtained at the nine measurement points is taken as the measurement value of one measurement area, and the average of the measurement values of the five measurement areas is determined to obtain the pitch of the convex 3c.
The pitches of convex portions of other shapes and the pitches of concave portions are also measured by the same measurement method.
　金属膜３の好ましい態様として、以下の態様Ａまたは態様Ｂが挙げられる。
　態様Ａ：金属膜内に長軸方向の長さが１μｍ以下の島状の隙間形状として設けられた、金属が存在せず基板１の第一面１ａが露出している複数の非成膜領域を有する金属膜。
　態様Ｂ：前記非成膜領域を有しない金属膜。 As a preferred embodiment of the metal film 3, the following embodiment A or embodiment B can be mentioned.
Aspect A: A plurality of non-film-forming areas provided as an island-like gap shape having a length of 1 μm or less in the major axis direction in the metal film and the first surface 1a of the substrate 1 is exposed without metal Metal film with.
Aspect B: a metal film not having the non-film formation region.
　金属膜３が態様Ａの金属膜（以下、金属膜３Ａともいう。）であれば、伝搬型表面プラズモンおよび局在型表面プラズモンによる増強電場それぞれの併用、もしくは伝搬型表面プラズモンおよび局在型表面プラズモンによる増強電場の共鳴結合（カップリング）を利用することで、光学的分析をより高感度に実施できる。一方、金属膜３が態様Ｂの金属膜（以下、金属膜３Ｂともいう。）であれば、伝搬型表面プラズモンによる増強電場を利用することで、光学的分析をより高感度に実施できる。 If the metal film 3 is a metal film of aspect A (hereinafter, also referred to as a metal film 3A), the combined use of the propagating surface plasmon and the enhanced electric field by the localized surface plasmon, or the propagating surface plasmon and the localized surface Optical analysis can be performed more sensitively by utilizing resonance coupling (coupling) of enhanced electric fields by plasmons. On the other hand, if the metal film 3 is a metal film of aspect B (hereinafter, also referred to as a metal film 3B), optical analysis can be performed with higher sensitivity by utilizing an enhanced electric field by propagating surface plasmons.
　金属膜３Ａについて、図４～５を参照してより詳細に説明する。図４は、金属膜３が金属膜３Ａである場合の分析用基板１０の金属膜３側の表面を模式的に示す拡大上面図であり、図５は、この分析用基板の図４におけるＩＶ－ＩＶ断面を模式的に示す部分断面図である。ただし、図４～５においては、金属ナノ粒子の図示は省略した。
　金属膜３Ａは、複数の非成膜領域Ｇを有する。複数の非成膜領域Ｇは、金属膜３Ａ内に長軸方向の長さが１μｍ以下の島状の隙間形状として分散して設けられている。金属膜３の非成膜領域Ｇ以外の領域は成膜領域である。
　非成膜領域Ｇは、金属が存在せず、第一面１ａが露出している領域である。つまり金属膜３Ａを厚さ方向に貫通している空隙（ギャップ）である。金属が厚さ方向の一部において存在していなくても金属膜３Ａを貫通している空隙とはなっていない領域（例えば図５中の領域Ｓ）は、非成膜領域Ｇには該当しない成膜領域である。 The metal film 3A will be described in more detail with reference to FIGS. FIG. 4 is an enlarged top view schematically showing the surface on the metal film 3 side of the analysis substrate 10 when the metal film 3 is the metal film 3A, and FIG. 5 is an IV in FIG. 4 of this analysis substrate. FIG. 4 is a partial cross-sectional view schematically showing a cross-section of FIG. However, in FIGS. 4 to 5, the illustration of the metal nanoparticles is omitted.
The metal film 3A has a plurality of non-film formation regions G. The plurality of non-film formation regions G are dispersedly provided in the metal film 3A as an island-like gap shape whose length in the long axis direction is 1 μm or less. A region other than the non-film formation region G of the metal film 3 is a film formation region.
The non-film formation region G is a region in which the first surface 1 a is exposed without the presence of metal. That is, it is a gap (gap) penetrating the metal film 3A in the thickness direction. A region (for example, a region S in FIG. 5) which is not a void penetrating the metal film 3A even if metal does not exist in a part in the thickness direction does not correspond to the non-film formation region G. It is a film formation area.
　非成膜領域Ｇは上面視で島状の隙間であり、複数の非成膜領域Ｇはそれぞれ独立している場合もあり、数個が連結している場合もあるが、全体として連結していない。したがって、非成膜領域Ｇは、図５に示すように、金属表面３ａによって囲まれており、非成膜領域Ｇを介して金属表面３ａ同士が対向している。非成膜領域Ｇを介して対向する金属表面間の距離、つまり非成膜領域Ｇの幅は通常、極めて小さく、例えば数ナノメートル～数十ナノメートルオーダーである。このような金属表面３ａ間では、局在型表面プラズモンによる電場の重ね合わせによって電場増強を発生させることができる。特に、非成膜領域Ｇの幅が一桁ナノメートルの場合は、極めて強力な電場増強が得られる。 The non-film formation area G is an island-shaped gap in a top view, and the plurality of non-film formation areas G may be independent of one another or may be several in number. Absent. Therefore, as shown in FIG. 5, the non-film formation area G is surrounded by the metal surface 3a, and the metal surfaces 3a face each other through the non-film formation area G. The distance between the metal surfaces facing each other through the non-film formation area G, that is, the width of the non-film formation area G is usually extremely small, for example, on the order of several nanometers to several tens of nanometers. Between such metal surfaces 3a, electric field enhancement can be generated by superposition of electric fields by localized surface plasmons. In particular, when the width of the non-film formation region G is one digit nanometer, extremely strong electric field enhancement is obtained.
　非成膜領域Ｇを介して対向する金属表面３ａ間の距離は、１～２０ｎｍが好ましく、１～１０ｎｍがより好ましく、１～５ｎｍがさらに好ましい。金属表面３ａ間の距離が前記範囲の範囲内であれば、局在型表面プラズモン共鳴による電場増強効果がより優れる。
　非成膜領域Ｇを囲む金属表面が、図５に示すように金属膜３の厚さ方向に対して傾斜した傾斜面である場合、金属表面３ａ間の距離には分布がある。金属表面３ａ間の距離に分布がある場合、金属表面３ａ間の距離の最大値が前記の好ましい上限値以下であることが好ましい。また、金属表面３ａ間の距離の最小値が前記の好ましい下限値以上であることが好ましい。
　金属表面３ａ間の距離は、後述する実施例に記載の方法により測定される。 The distance between the metal surfaces 3a facing each other through the non-film formation region G is preferably 1 to 20 nm, more preferably 1 to 10 nm, and still more preferably 1 to 5 nm. If the distance between the metal surfaces 3a is within the above range, the electric field enhancing effect by localized surface plasmon resonance is more excellent.
When the metal surface surrounding the non-film formation region G is an inclined surface inclined with respect to the thickness direction of the metal film 3 as shown in FIG. 5, there is a distribution in the distance between the metal surfaces 3a. When distribution exists in the distance between the metal surfaces 3a, it is preferable that the maximum value of the distance between the metal surfaces 3a is below the said preferable upper limit. Moreover, it is preferable that the minimum value of the distance between the metal surfaces 3a is more than the said preferable lower limit.
The distance between the metal surfaces 3a is measured by the method described in the examples to be described later.
　金属膜３Ａの厚さは、非成膜領域Ｇ以外の領域、つまり成膜領域の平均厚さとして、３～４０ｎｍが好ましく、４～３０ｎｍがより好ましく、５～２０ｎｍが最も好ましい。金属膜３Ａの厚さが前記範囲内であれば、非成膜領域Ｇを有し、非成膜領域Ｇを介して対向する金属表面間の距離、金属膜３Ａの総面積に対する非成膜領域Ｇの面積の割合がそれぞれ前記の好ましい範囲内である金属膜３Ａとなりやすい。金属膜３Ａの厚さが前記下限値以上であれば、金属膜３Ａの表面のシート抵抗が前記上限値以下となりやすい。 The thickness of the metal film 3A is preferably 3 to 40 nm, more preferably 4 to 30 nm, and most preferably 5 to 20 nm as the average thickness of the region other than the non-film formation region G, ie, the film formation region. If the thickness of the metal film 3A is within the above range, the non-film formation region G is provided, and the distance between the metal surfaces opposed via the non-film formation region G, the non-film formation region with respect to the total area of the metal film 3A It tends to become the metal film 3A in which the ratio of the area of G is within the above preferable range. If the thickness of the metal film 3A is equal to or more than the lower limit value, the sheet resistance of the surface of the metal film 3A is likely to be equal to or less than the upper limit value.
　金属膜３Ａの厚さ（成膜領域の平均厚さ）は、以下の方法で求められる成膜レートから算出される値である。先ず単結晶シリコン基板等、原子間力顕微鏡（ＡＦＭ）によって求められる中心線平均粗さＲａが１ｎｍ以下の平坦な基材を準備し、これにテープ等でマスクをし、その後金属膜を数～数十ｎｍ程度一定時間成膜し、マスクを除去した後、成膜厚さをＡＦＭで測定する。上記情報より、成膜レート（単位時間当たりの成膜厚さ（ｎｍ／ｍｉｎ））を求める。成膜レートが求まれば、この成膜レートと金属膜３Ａを成膜する際の成膜時間から金属膜３Ａの厚さを算出することができる。
　上記方法において、便宜上、ＡＦＭの代わりに触針式段差計を用いて成膜厚さを測定してもよい。この場合でも同様の結果が得られるが、ＡＦＭと触針式段差計による測定値が異なる場合は、本発明においてはＡＦＭによる測定値を採用する。
　金属膜３Ａの厚さは、便宜上、透過型電子顕微鏡（ＴＥＭ）を使用して、金属膜３Ａを含む基板の断面サンプルの顕微鏡像を取得し、像中で金属膜３Ａの厚さを実測する方法で測定してもよい。この場合でも同様の結果が得られる。この方法は、成膜レート等の情報を予め測定する必要が無いため、製造条件等が未知のサンプルに対して有効な手段となる。
　成膜レート未知のサンプルの金属膜３Ａの厚さを知るための他の方法としては、ナイフなどを用いて極めて細い傷を金属膜３Ａの表面に形成し、その傷の深さをＡＦＭによって測長する方法が有効である。金属膜３Ａは極めて薄いため、比較的弱い力で基材が露出する傷を形成することが可能である。 The thickness of the metal film 3A (average thickness of the film formation region) is a value calculated from the film formation rate obtained by the following method. First, a flat substrate such as a single crystal silicon substrate or the like and having a center line average roughness Ra of 1 nm or less obtained by atomic force microscope (AFM) is prepared, and is masked with a tape etc. After forming a film for a fixed time of about several tens of nm and removing the mask, the film thickness is measured by AFM. From the above information, the deposition rate (deposition thickness per unit time (nm / min)) is determined. Once the film formation rate is determined, the thickness of the metal film 3A can be calculated from the film formation rate and the film formation time for forming the metal film 3A.
In the above method, for convenience, the thickness of the film may be measured using a stylus type profilometer instead of AFM. In this case, similar results can be obtained, but in the case where the measurement values by the AFM and the stylus type profilometer differ, in the present invention, the measurement values by the AFM are adopted.
For the thickness of the metal film 3A, for convenience, a microscopic image of a cross-sectional sample of the substrate including the metal film 3A is acquired using a transmission electron microscope (TEM), and the thickness of the metal film 3A is measured in the image. It may be measured by a method. Similar results are obtained in this case as well. Since this method does not need to measure information such as the film formation rate in advance, this method is an effective means for samples whose manufacturing conditions and the like are unknown.
As another method to know the thickness of the metal film 3A of the sample whose film forming rate is unknown, an extremely thin scratch is formed on the surface of the metal film 3A using a knife or the like, and the depth of the scratch is measured by AFM. The method of lengthening is effective. Since the metal film 3A is extremely thin, it is possible to form a scratch in which the substrate is exposed with a relatively weak force.
　金属膜３Ｂの厚さは、４０～４００ｎｍ以下がより好ましく、５０～２００ｎｍがさらに好ましい。金属膜３Ｂの厚さが前記下限値以上であれば、非成膜領域を有しない金属膜となりやすい。また、金属膜３ＢＡの厚さが前記範囲内であれば、金属膜３Ａの表面のシート抵抗が範囲内となりやすい。
　金属膜３Ｂの厚さは、金属膜３Ａの厚さと同様にして測定される。 The thickness of the metal film 3B is more preferably 40 to 400 nm or less, further preferably 50 to 200 nm. If the thickness of the metal film 3B is equal to or more than the above lower limit value, it tends to be a metal film having no non-film formation region. If the thickness of the metal film 3BA is within the above range, the sheet resistance of the surface of the metal film 3A is likely to be within the range.
The thickness of the metal film 3B is measured in the same manner as the thickness of the metal film 3A.
（金属ナノ粒子）
　金属ナノ粒子５を構成する金属としては、表面プラズモン共鳴による電場増強を発生させ得るものであればよく、例えば金、銀、アルミニウム、銅、白金、これらの２種以上の合金等が挙げられる。
　金属ナノ粒子５の形状は、特に限定されず、例えば球状、針状（棒状）、フレーク状、多面体状、リング状、中空状（中心部は空洞若しくは誘電体が存在する）、樹状結晶、その他不定形状等が挙げられる。
　複数の金属ナノ粒子５の少なくとも一部が凝集して二次粒子を形成していてもよい。 (Metal nanoparticles)
The metal constituting the metal nanoparticles 5 may be any metal as long as it can generate electric field enhancement by surface plasmon resonance, and examples thereof include gold, silver, aluminum, copper, platinum, alloys of two or more of these, and the like.
The shape of the metal nanoparticles 5 is not particularly limited, and may be, for example, spherical, needle-like (rod-like), flake-like, polyhedral-like, ring-like, hollow (in the center part, a cavity or a dielectric exists), dendritic crystals, Other irregular shapes are also included.
At least a part of the plurality of metal nanoparticles 5 may be aggregated to form a secondary particle.
　金属ナノ粒子５の平均一次粒子径は、５～１００ｎｍであり、５～８０ｎｍが好ましく、５～４０ｎｍがより好ましい。金属ナノ粒子５の平均一次粒子径が前記範囲内であれば、局在型表面プラズモン共鳴による電場増強効果が優れる。
　金属ナノ粒子５の平均一次粒子径は、走査型電子顕微鏡（ＳＥＭ）によって直接金属ナノ粒子５の一次粒子径を測長し、その平均値を得る方法によって測定される。この場合、平均的な状態を知るため、ｎ＝２０以上の平均値を取得する。
　上記方法において、便宜上、ＳＥＭの代わりに、透過型電子顕微鏡（ＴＥＭ）又は原子間力顕微鏡（ＡＦＭ）を用いてもよい。この場合でも同様の結果が得られる。
　金属ナノ粒子５の平均一次粒子径は、便宜上、動的光散乱法による粒度分布計によって測定してもよい。この場合、二次粒子（一次粒子が凝集した集合体）が存在すると粒度分布曲線に複数のピークが生じるため、最も小さい粒子径のピークが目的の粒子径となる。この方法でも上記ＳＥＭを用いた測定方法と同様の結果が得られる。
　ＳＥＭ等の顕微鏡的手段を用いる測定方法は製品としての分析用基板の表面を後から分析する場合に有用であり、動的光散乱法による測定方法は分析用基板を製造する際に有用である。 The average primary particle diameter of the metal nanoparticles 5 is 5 to 100 nm, preferably 5 to 80 nm, and more preferably 5 to 40 nm. If the average primary particle diameter of the metal nanoparticles 5 is within the above range, the electric field enhancing effect by localized surface plasmon resonance is excellent.
The average primary particle size of the metal nanoparticles 5 is measured by a method of directly measuring the primary particle size of the metal nanoparticles 5 by a scanning electron microscope (SEM) and obtaining an average value thereof. In this case, in order to know an average state, an average value of n = 20 or more is acquired.
In the above method, for convenience, a transmission electron microscope (TEM) or an atomic force microscope (AFM) may be used instead of the SEM. Similar results are obtained in this case as well.
The average primary particle size of the metal nanoparticles 5 may be conveniently measured by a particle size distribution analyzer by a dynamic light scattering method. In this case, when secondary particles (aggregates in which primary particles are aggregated) are present, a plurality of peaks are generated in the particle size distribution curve, and therefore the peak with the smallest particle diameter is the target particle diameter. Also in this method, the same result as the measurement method using the above SEM can be obtained.
A measuring method using a microscopic means such as SEM is useful when analyzing the surface of a substrate for analysis as a product later, and a measuring method by dynamic light scattering method is useful for producing an analytical substrate .
　金属膜３上に離間して配置された、隣り合う２つの金属ナノ粒子５間の最短距離は、１～２０ｎｍが好ましく、１～１０ｎｍがより好ましく、１～５ｎｍがさらに好ましい。前記最短距離が前記範囲内であれば、各金属ナノ粒子５の間で局在型表面プラズモン共鳴による電場増強が発生し、各金属ナノ粒子５の間に吸着した測定対象分子の高感度ラマン分光分析が可能となる。また、金属膜３に対して金属ナノ粒子５が接地していても、その接点近傍には金属膜３と金属ナノ粒子５の微小な隙間が発生するため、ここでも局在型表面プラズモン共鳴による電場増強が発生し高感度ラマン分光分析が可能となる。
　前記最短距離は、走査型電子顕微鏡（ＳＥＭ）を用いて、隣り合う２つの金属ナノ粒子を含む基板の表面サンプルの顕微鏡像を取得し、像中で隣り合う２つの金属ナノ粒子の間隙を実測する方法によって測定される。この方法は、１０万倍以上、好ましくは１００万倍以上の倍率を必要とする。隣り合う２つの金属ナノ粒子５間の最短距離は局所的に異なり、一様ではないため、ｎ＝２０以上の測定を行い、距離の分布を取得する。
　上記方法において、便宜上、ＳＥＭの代わりに、透過型電子顕微鏡（ＴＥＭ）又は原子間力顕微鏡（ＡＦＭ）を用いてもよい。この場合でも同様の結果が得られる。
　ただし、表面増強ラマン散乱効果に最も有効に寄与するのは、１ｎｍ程度のナノギャップとも言われており、必ずしも距離の分布の平均値が意味を持つ数値にはならない。 The shortest distance between two adjacent metal nanoparticles 5 arranged on the metal film 3 at a distance is preferably 1 to 20 nm, more preferably 1 to 10 nm, and still more preferably 1 to 5 nm. If the shortest distance is within the above range, electric field enhancement occurs by localized surface plasmon resonance between the metal nanoparticles 5, and high sensitivity Raman spectroscopy of the measurement target molecules adsorbed between the metal nanoparticles 5 Analysis is possible. In addition, even if the metal nanoparticles 5 are grounded to the metal film 3, minute gaps between the metal film 3 and the metal nanoparticles 5 are generated in the vicinity of the contact points, so here also by localized surface plasmon resonance. Electric field enhancement occurs to enable highly sensitive Raman spectroscopy.
The said shortest distance acquires the microscopic image of the surface sample of the board | substrate containing two adjacent metal nanoparticles using a scanning electron microscope (SEM), and measures the gap of two adjacent metal nanoparticles in the image. Measured by the method. This method requires a magnification of at least 100,000, preferably at least a million. Since the shortest distance between two adjacent metal nanoparticles 5 is locally different and not uniform, measurement of n = 20 or more is performed to obtain a distribution of distances.
In the above method, for convenience, a transmission electron microscope (TEM) or an atomic force microscope (AFM) may be used instead of the SEM. Similar results are obtained in this case as well.
However, what is most effectively contributed to the surface enhanced Raman scattering effect is said to be a nanogap of about 1 nm, and the average value of the distribution of distances does not necessarily have a meaning.
（分析用基板の製造方法）
　分析用基板１０の製造方法としては、例えば、以下の製造方法（Ｉ）が挙げられる。
　製造方法（Ｉ）：
　基板１の第一面１ａ上に金属を堆積させて金属膜３を成膜する工程（以下、「工程Ｉ－１」ともいう。）と、
　複数の金属ナノ粒子５と分散媒とを含む金属ナノ粒子分散液を金属膜３上に塗布し、乾燥する工程（以下、「工程Ｉ－２」ともいう。）と、を含む、分析用基板の製造方法。
　工程Ｉ－１において、第一面１ａ上に、金属の堆積していない複数の領域が、長軸方向の長さが１μｍ以下の島状の隙間形状として残り、金属膜の表面のシート抵抗が５０００Ω／□以下となった状態で、第一面１ａ上への金属の堆積を終了すると、金属膜３Ａとなる。金属の堆積を終了せずにそのまま続けると、非成膜領域Ｇが消失し、膜表面の凹凸が小さくなって、平坦な表面を有する金属膜３Ｂとなる。 (Manufacturing method of substrate for analysis)
Examples of the method for producing the analysis substrate 10 include the following production method (I).
Production method (I):
And depositing a metal on the first surface 1a of the substrate 1 to form a metal film 3 (hereinafter, also referred to as “step I-1”).
And a step of applying a metal nanoparticle dispersion liquid containing a plurality of metal nanoparticles 5 and a dispersion medium on the metal film 3 and drying it (hereinafter, also referred to as “step I-2”). Manufacturing method.
In step I-1, a plurality of regions where metal is not deposited remain on the first surface 1a as island-like gaps having a length of 1 μm or less in the long axis direction, and sheet resistance on the surface of the metal film When deposition of metal on the first surface 1a is completed in a state of 5000 Ω / □ or less, the metal film 3A is obtained. If the deposition of metal is continued without completion, the non-film formation region G disappears, and the unevenness of the film surface becomes small, and the metal film 3B having a flat surface is formed.
　＜工程Ｉ－１＞
　基板１としては、表面に二次元格子構造を形成した原版又はその転写品を用いることができる。かかる原版又はその転写品は、公知の製造方法により製造したものを用いてもよく、市販のものを用いてもよい。 <Step I-1>
As the substrate 1, an original plate having a two-dimensional lattice structure formed on the surface or a transferred product thereof can be used. Such an original plate or a transferred product thereof may be one produced by a known production method or a commercially available one.
　原版は、原板の表面に二次元格子構造を形成することにより得られる。
　原板は、表面に所定の二次元格子構造を有しない以外は、基板１と同様である。
　原板の表面に二次元格子構造を形成する方法としては、たとえば、単粒子膜をエッチングマスクとしたドライエッチング法（コロイダルリソグラフィー法）、電子ビームリソグラフィー法、機械式切削加工法、レーザー熱リソグラフィー法、干渉露光法、より具体的には二光束干渉露光法、縮小露光法、アルミナの陽極酸化法、およびそれらのいずれかの方法により作製した、表面に二次元格子構造を有する転写原版からのナノインプリント法等が挙げられる。 The original plate is obtained by forming a two-dimensional lattice structure on the surface of the original plate.
The original plate is the same as the substrate 1 except that the original plate does not have a predetermined two-dimensional lattice structure on the surface.
As a method of forming a two-dimensional lattice structure on the surface of the original plate, for example, dry etching (colloidal lithography) using a single particle film as an etching mask, electron beam lithography, mechanical cutting, laser thermal lithography, Nanoimprint method from a transfer master having a two-dimensional lattice structure on the surface, which is manufactured by the interference exposure method, more specifically, the two-beam interference exposure method, the reduction exposure method, the anodic oxidation method of alumina, and any of them. Etc.
　二次元格子構造の形成方法としては、様々な方法が適用可能で、例えば電子線描画とドライエッチングを組み合わせたフォトリソグラフィー法やナノポーラスアルミナ陽極酸化法、或いはそれによる原盤を用いるナノインプリント法などが挙げられるが、大面積・低コストで微細構造体を作製できる点で、単粒子膜をエッチングマスクとしたドライエッチング法（コロイダルリソグラフィー法）が好ましい。また、コロイダルリソグラフィー法は、容易に複数種のピッチの異なる構造体を作製することが可能で、構造の最適化および機能検証が迅速に行えるという利点がある。
　コロイダルリソグラフィー法による基板１の製造は、より具体的には、原板（表面に二次元格子構造を形成する前の基板）上に単粒子膜を配置する工程（単粒子膜配置工程）と、前記単粒子膜および前記原板をドライエッチングする工程（ドライエッチング工程）とを含む製造方法により行うことができる。
　単粒子膜および各工程については後で詳細に説明する。 As a method of forming a two-dimensional lattice structure, various methods can be applied, such as a photolithography method combining electron beam drawing and dry etching, a nanoporous alumina anodic oxidation method, or a nanoimprint method using a master obtained therefrom. However, a dry etching method (colloidal lithography method) using a single particle film as an etching mask is preferable in that a microstructure can be produced with a large area and low cost. In addition, the colloidal lithography method can easily produce a plurality of structures with different pitches, and has an advantage that structure optimization and functional verification can be performed quickly.
More specifically, in the production of the substrate 1 by the colloidal lithography method, a step of disposing a single particle film on an original plate (a substrate before forming a two-dimensional lattice structure on the surface) (a single particle film disposing step); It can carry out by the manufacturing method including the process (dry etching process) which dry-etches a single particle film and the said original plate.
The monoparticulate film and each step will be described in detail later.
　第一面１ａ上に金属を堆積する方法としては、特に限定されず、例えば蒸着法等の乾式法、電解メッキや無電解メッキ等の湿式法等が挙げられる。乾式法としては、例えば各種真空スパッタリング法、真空蒸着法等の物理蒸着法（ＰＶＤ）、各種化学蒸着法（ＣＶＤ）等が挙げられる。 The method of depositing the metal on the first surface 1a is not particularly limited, and examples thereof include dry methods such as vapor deposition, and wet methods such as electrolytic plating and electroless plating. Examples of the dry method include various vacuum sputtering methods, physical vapor deposition methods (PVD) such as vacuum deposition methods, and various chemical vapor deposition methods (CVD).
　第一面１ａに対して乾式法により金属膜の成膜（金属の堆積）を行うと、まず、第一面１ａ全体に複数の金属粒子が付着し、金属粒子同士が成長により接合して微細な島状の金属膜が複数形成される。成膜が進むにつれて、隣り合う金属膜同士がより大きなクラスターを形成し、金属膜の面積と厚さが増加していく。これに伴い、第一面１ａ上の金属の堆積していない領域が狭くなっていく。金属の堆積していない領域が島状に残り、形成された金属膜の表面シート抵抗の値が前記範囲内となった状態（金属膜が連続膜となった状態）で成膜を終了することで、前述の金属膜３Ａが得られる。島状に残った、金属の堆積していない領域が非成膜領域Ｇとなる。金属の堆積を終了せずにそのまま続けると、非成膜領域Ｇが消失し、金属膜３Ｂとなる。 When metal film deposition (metal deposition) is performed on the first surface 1a by a dry method, first, a plurality of metal particles adhere to the entire first surface 1a, and the metal particles are joined by growth to form fine particles. Plural island-shaped metal films are formed. As film formation proceeds, adjacent metal films form larger clusters, and the area and thickness of the metal films increase. Along with this, the region where the metal is not deposited on the first surface 1a becomes narrower. The film formation is completed in a state in which the area where the metal is not deposited remains like an island and the value of the surface sheet resistance of the formed metal film falls within the above range (the metal film becomes a continuous film). Thus, the aforementioned metal film 3A is obtained. An area in which the island remains and in which the metal is not deposited is a non-film formation area G. If the deposition of metal is continued without completion, the non-film formation region G disappears and it becomes the metal film 3B.
　第一面１ａ上に予め触媒を分散配置し、その状態で無電解メッキによる金属膜の成膜を行うと、まず、触媒の周囲に金属が付着し、微細な島状の金属膜が複数形成される。無電解メッキが進むにつれて、乾式法の場合と同様に、金属膜同士がより大きなクラスターを形成し、第一面１ａ上の金属の堆積していない領域が狭くなっていく。金属の堆積していない領域が島状に残り、形成された金属膜の表面シート抵抗値が前記範囲内となった状態で成膜を終了することで、前述の金属膜３Ａが得られる。島状に残った、金属の堆積していない領域が非成膜領域Ｇとなる。金属の堆積を終了せずにそのまま続けると、非成膜領域Ｇが消失し、金属膜３Ｂとなる。 When a catalyst is dispersedly disposed on the first surface 1a in advance and a metal film is formed by electroless plating in that state, first, metal adheres to the periphery of the catalyst, and a plurality of fine island-shaped metal films are formed. Be done. As the electroless plating progresses, as in the case of the dry method, the metal films form larger clusters, and the region on which the metal is not deposited on the first surface 1a is narrowed. The above-described metal film 3A is obtained by completing the film formation in a state where the region where metal is not deposited remains in an island shape and the surface sheet resistance value of the formed metal film is in the above range. An area in which the island remains and in which the metal is not deposited is a non-film formation area G. If the deposition of metal is continued without completion, the non-film formation region G disappears and it becomes the metal film 3B.
　第一面１ａ上に金属を堆積する方法としては、不純物の付着が起こりにくく、金属膜の基材に対する付着強度が高く、海島構造のコントロールが行いやすい点から、スパッタリング法が好ましい。すなわち金属膜３がスパッタリング法で成膜された膜であることが好ましい。
　第一面１ａ上に金属の堆積していない複数の領域が島状に残っていることは、原子間力顕微鏡（ＡＦＭ）、走査型電子顕微鏡（ＳＥＭ）等の高倍率顕微鏡手段による１０万倍程度の表面観察により確認できる。
　蒸着を終了する際の金属膜３の表面のシート抵抗は、３～５００Ω／□が好ましく、３～３００Ω／□が最も好ましい。 As a method of depositing a metal on the first surface 1a, a sputtering method is preferable from the viewpoint that adhesion of impurities is difficult to occur, adhesion strength of a metal film to a substrate is high, and control of sea-island structure is easily performed. That is, the metal film 3 is preferably a film formed by sputtering.
The fact that a plurality of regions where metal is not deposited remains in the form of islands on the first surface 1a is 100,000 times as large as with a high magnification microscope such as atomic force microscope (AFM) or scanning electron microscope (SEM) This can be confirmed by surface observation of the degree.
The sheet resistance of the surface of the metal film 3 at the end of the deposition is preferably 3 to 500 Ω / □, and most preferably 3 to 300 Ω / □.
　＜工程Ｉ－２＞
　金属ナノ粒子分散液の分散媒としては、金属ナノ粒子５を分散可能なものであればよく、例えば水、エタノール、その他有機溶剤等が挙げられる。
　金属ナノ粒子分散液中の金属ナノ粒子５の含有量は、例えば、金属ナノ粒子分散液の総質量に対し、０．０１～１０．０質量％であってよく、さらには０．１～１．０質量％であってよい。
　金属ナノ粒子分散液は、必要に応じて、発明の効果を損なわない範囲で、分散安定剤としてのクエン酸や各種無機塩等をさらに含んでいてもよい。 <Step I-2>
The dispersion medium of the metal nanoparticle dispersion liquid may be any one as long as the metal nanoparticles 5 can be dispersed, and examples thereof include water, ethanol, and other organic solvents.
The content of the metal nanoparticles 5 in the metal nanoparticle dispersion may be, for example, 0.01 to 10.0 mass% with respect to the total mass of the metal nanoparticle dispersion, and further 0.1 to 1 It may be 0 mass%.
The metal nanoparticle dispersion may further contain citric acid, various inorganic salts, and the like as a dispersion stabilizer, as needed, as long as the effects of the invention are not impaired.
　金属ナノ粒子分散液の塗布方法としては、特に限定されず、例えばスプレー法、ドロップキャスト法、ディップコート法、スピンコート法、インクジェット印刷法等の公知の塗布方法のなかから適宜選定できる。金属ナノ粒子散布により基板表面における金属ナノ粒子を高密度かつ均一に配置できる点で、スプレー法またはインクジェット印刷法が好ましい。 It does not specifically limit as a coating method of a metal nanoparticle dispersion liquid, For example, it can select suitably from well-known coating methods, such as a spray method, a drop cast method, a dip coating method, a spin coat method, an inkjet printing method. The spray method or the inkjet printing method is preferable in that metal nanoparticles can be densely and uniformly arranged on the substrate surface by metal nanoparticle dispersion.
　工程Ｉ－１の後、又は工程Ｉ－２の後、通常の環境下（空気中）で長期保管を行うと、基板表面の金属構造体に空気中の汚染物質が付着し本発明の効果が低下するおそれがある。そのため、保管は真空容器または窒素やアルゴン等の不活性ガス中で行うことが好ましい。もし空気中の汚染物質によって本発明の効果が低下した場合には、必要に応じて、その機能を回復するために、同基板に対して紫外線（ＵＶ）／オゾン等の表面処理を行ってもよい。 After step I-1 or after step I-2, when stored for a long time under normal environment (in air), contaminants in the air adhere to the metal structure on the substrate surface, and the effect of the present invention It may decrease. Therefore, storage is preferably performed in a vacuum vessel or an inert gas such as nitrogen or argon. If the effect of the present invention is reduced due to contaminants in the air, the substrate may be subjected to surface treatment such as ultraviolet (UV) / ozone to restore its function, if necessary. Good.
　＜単粒子膜＞
　「単粒子膜」は、複数の粒子が二次元に配列した単層膜である。
　単粒子膜を構成する粒子の材料としては、特に限定されず、有機材料でもよく、無機材料でもよく、有機材料と無機材料との複合材料でもよい。
　有機材料としては、例えばポリスチレン、ポリメチルメタクリレート（ＰＭＭＡ）等の熱可塑性樹脂；フェノール樹脂、エポキシ樹脂等の熱硬化性樹脂；等が挙げられる。
　無機材料としては、例えば、炭素同素体、無機炭化物、無機酸化物、無機窒化物、無機硼化物、無機硫化物、無機セレン化物等が挙げられる。炭素同素体としては、例えばダイヤモンド、グラファイト、フラーレン類等が挙げられる。無機炭化物としては、例えば炭化ケイ素、炭化硼素等が挙げられる。無機酸化物としては、例えば酸化ケイ素、酸化アルミニウム、酸化ジルコニウム、酸化チタン、酸化セリウム、酸化亜鉛、酸化スズ、イットリウムアルミニウムガーネット（ＹＡＧ）等が挙げられる。無機窒化物としては、例えば窒化珪素、窒化アルミニウム、窒化硼素等が挙げられる。無機硼化物としては、例えばＺｒＢ２、ＣｒＢ２等が挙げられる。無機硫化物としては、例えば硫化亜鉛、硫化カルシウム、硫化カドミウム、硫化ストロンチウム等が挙げられる。無機セレン化物としては、例えばセレン化亜鉛、セレン化カドミウム等が挙げられる。
　粒子を構成する材料は１種でもよく２種以上でもよい。 <Single particle film>
The “single particle film” is a single layer film in which a plurality of particles are two-dimensionally arranged.
The material of the particles constituting the single particle film is not particularly limited, and may be an organic material, an inorganic material, or a composite material of an organic material and an inorganic material.
Examples of the organic material include thermoplastic resins such as polystyrene and polymethyl methacrylate (PMMA); thermosetting resins such as phenol resin and epoxy resin; and the like.
Examples of the inorganic material include carbon allotropes, inorganic carbides, inorganic oxides, inorganic nitrides, inorganic borides, inorganic sulfides, inorganic selenides and the like. Examples of the carbon allotrope include diamond, graphite, fullerenes and the like. Examples of inorganic carbides include silicon carbide and boron carbide. Examples of the inorganic oxide include silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, zinc oxide, tin oxide, yttrium aluminum garnet (YAG) and the like. Examples of the inorganic nitride include silicon nitride, aluminum nitride, boron nitride and the like. Examples of inorganic borides include ZrB 2 and CrB 2 . Examples of inorganic sulfides include zinc sulfide, calcium sulfide, cadmium sulfide, strontium sulfide and the like. Examples of inorganic selenides include zinc selenide and cadmium selenide.
The material constituting the particles may be one kind or two or more kinds.
　単粒子膜を構成する粒子の平均粒子径は、分光分析に用いる励起波長に合わせて上述の方法で算出した周期的凹凸構造のピッチに相当する。粒子の平均粒子径が前記計算値であれば、伝搬型表面プラズモンを誘起しやすくなる。
　単粒子膜を構成していないスラリー状態の粒子の平均粒子径は、粒子動的光散乱法により求めた粒度分布をガウス曲線にフィッティングさせて得られるピークから常法により求めることができる平均一次粒子径のことである。 The average particle diameter of the particles constituting the single particle film corresponds to the pitch of the periodic uneven structure calculated by the above-mentioned method in accordance with the excitation wavelength used for the spectral analysis. If the average particle diameter of the particles is the above calculated value, propagation surface plasmons are easily induced.
The average particle diameter of the particles in a slurry state not constituting the single particle film can be determined by a conventional method from the peak obtained by fitting the particle size distribution determined by the particle dynamic light scattering method to a Gaussian curve It is the diameter.
　図２に示すような三角格子構造の二次元格子構造を形成する場合、単粒子膜を構成する粒子の粒子径の変動係数（標準偏差を平均値で除した値）は、２０％以下が好ましく、１０％以下がより好ましく、５％以下がさらに好ましい。このように粒子径の変動係数、すなわち、粒子径のばらつきが小さい粒子を使用すると、形成される単粒子膜に、粒子が存在しない欠陥箇所が生じにくくなり、粒子の配列のずれＤが１０％以下である高精度の単粒子膜を得ることができる。配列のずれＤが１０％以下である単粒子膜は、各粒子が二次元に最密充填し、粒子の間隔が制御されていて、その配列の精度が高い。よって、このような単粒子膜を原板上に配置し、ドライエッチングを行うと、原板表面に高精度な二次元格子構造を形成できる。
　ただし本発明はこれに限定されるものではなく、粒子径の変動係数の大きい粒子で単粒子膜を構成してもよい。例えば平均粒子径の異なる複数の粒子群を混合したものを用いて単粒子膜を構成してもよい。 When forming a two-dimensional lattice structure having a triangular lattice structure as shown in FIG. 2, the coefficient of variation (the value obtained by dividing the standard deviation by the average value) of the particle diameter of the particles constituting the single particle film is preferably 20% or less 10% or less is more preferable, and 5% or less is more preferable. As described above, when particles having a small variation coefficient of particle diameter, that is, small variation of particle diameter, are used, it becomes difficult to form a defect location where particles do not exist in the formed single particle film, and misalignment D of the arrangement of particles is 10%. It is possible to obtain a highly accurate single particle film which is as follows. In a single particle film in which the misalignment D is 10% or less, each particle is two-dimensionally close-packed, the particle spacing is controlled, and the accuracy of the alignment is high. Therefore, if such a single particle film is disposed on the original plate and dry etching is performed, a highly accurate two-dimensional lattice structure can be formed on the surface of the original plate.
However, the present invention is not limited to this, and a single particle film may be composed of particles having a large variation coefficient of particle diameter. For example, a single particle film may be configured using a mixture of a plurality of particle groups having different average particle sizes.
　粒子の配列のずれＤは、下記式（１）で定義される。
　Ｄ［％］＝｜Ｂ－Ａ｜×１００／Ａ・・・（１）
　式（１）中、Ａは単粒子膜を構成している粒子の平均粒子径、Ｂは単粒子膜における粒子間の平均ピッチである。また、｜Ｂ－Ａ｜はＡとＢとの差の絶対値を示す。
　ここで、粒子の平均粒子径とは、前記で定義したとおりである。
　粒子間のピッチとは、隣り合う２つの粒子の頂点と頂点の距離であり、平均ピッチとはこれらを平均したものである。なお、粒子が球形であれば、隣り合う２つの粒子の頂点と頂点との距離は、隣り合う２つの粒子の中心と中心の距離と等しい。 The deviation D of the arrangement of particles is defined by the following formula (1).
D [%] = | B-A | × 100 / A (1)
In Formula (1), A is an average particle diameter of particles constituting a single particle film, and B is an average pitch between particles in the single particle film. Also, | B−A | indicates the absolute value of the difference between A and B.
Here, the average particle size of the particles is as defined above.
The pitch between particles is the distance between the apexes of two adjacent particles, and the average pitch is the average of these. If the particles are spherical, the distance between the apexes of two adjacent particles is equal to the distance between the centers of the two adjacent particles.
　単粒子膜における粒子間の平均ピッチＢは、具体的には次のようにして求められる。
　まず、単粒子膜における無作為に選択された領域で、一辺が微細構造の繰り返し単位３０～４０波長分の正方形の領域について、原子間力顕微鏡イメージ又は走査型電子顕微鏡イメージを得る。例えば粒子径３００ｎｍの粒子を用いた単粒子膜の場合、９μｍ×９μｍ～１２μｍ×１２μｍの領域のイメージを得る。そして、このイメージを２次元フーリエ変換により波形分離し、ＦＦＴ像（高速フーリエ変換像）を得る。ついで、ＦＦＴ像のプロファイルにおける０次ピークから１次ピークまでの距離を求める。こうして求められた距離の逆数がこの領域における平均ピッチＢ１である。このような処理を無作為に選択された合計２５カ所以上の同面積の領域について同様に行い、各領域における平均ピッチＢ１～Ｂ２５を求める。こうして得られた２５カ所以上の領域における平均ピッチＢ１～Ｂ２５の平均値が式（１）における平均ピッチＢである。なお、この際、各領域同士は、少なくとも１ｍｍ離れて選択されることが好ましく、より好ましくは５ｍｍ～１ｃｍ離れて選択される。
　また、この際、ＦＦＴ像のプロファイルにおける１次ピークの半値幅から、各イメージについて、その中の粒子間のピッチのばらつきを評価することもできる。 Specifically, the average pitch B between particles in the single particle film is determined as follows.
First, an atomic force microscope image or a scanning electron microscope image is obtained for a square region of 30 to 40 wavelengths of repeating units of a fine structure in a randomly selected region of a single particle film. For example, in the case of a single particle film using particles of 300 nm in particle diameter, an image of a region of 9 μm × 9 μm to 12 μm × 12 μm is obtained. Then, this image is waveform separated by two-dimensional Fourier transform to obtain an FFT image (fast Fourier transform image). Next, the distance from the zero-order peak to the first-order peak in the profile of the FFT image is determined. Thus the inverse of the calculated distance is the average pitch B 1 in this region. Such processing is similarly performed on randomly selected areas of 25 areas or more having the same area in total, and average pitches B 1 to B 25 in each area are determined. The average value of the average pitches B 1 to B 25 in the region of 25 or more places thus obtained is the average pitch B in the equation (1). In this case, the respective regions are preferably selected to be separated by at least 1 mm, and more preferably selected to be separated by 5 mm to 1 cm.
At this time, it is also possible to evaluate, for each image, the variation in pitch among particles in each image from the half width of the primary peak in the profile of the FFT image.
　＜単粒子膜配置工程＞
　単粒子膜配置工程は、ラングミュア－ブロジェット法（ＬＢ法）により行われることが好ましい。この方法は、単層化の精度、操作の簡便性、大面積化への対応、再現性等を兼ね備え、例えばNature, Vol.361, 7 January, 26（1993）等に記載されている液体薄膜法や特開昭５８－１２０２５５号公報等に記載されているいわゆる粒子吸着法に比べて非常に優れ、工業生産レベルにも対応できる。 <Single particle film placement process>
The single particle film disposing step is preferably performed by the Langmuir-Blodgett method (LB method). This method combines the accuracy of single-layering, the simplicity of operation, the response to an increase in area, the reproducibility, etc., for example, the liquid thin film described in Nature, Vol. 361, 7 January, 26 (1993), etc. It is extremely superior to the so-called particle adsorption method described in U.S. Pat.
　ＬＢ法による単粒子膜配置工程は、例えば、その液面上で粒子を展開させるための液体（以下、下層液という場合もある。）として水を入れた水槽（トラフ）を用意し、その液面に、水よりも比重の小さい有機溶剤中に粒子が分散した分散液を滴下する工程（滴下工程）と、前記有機溶剤を揮発させることにより粒子からなる単粒子膜を形成する工程（単粒子膜形成工程）と、形成した単粒子膜を原板に移し取る工程（移行工程）と、を含む方法により実施できる。移行工程後に、基板に移し取った単粒子膜を基板に固定する工程（固定工程）を行ってもよい。
　このとき、粒子としては、粒子が親水性の下層液の液面下に潜ってしまわないように、表面が疎水性である粒子が用いられる。また、有機溶剤としては、分散液を下層液の液面に滴下した際に分散液が下層液と混和せずに空気と下層液の気液界面に展開するように、疎水性のものが選択される。
　なお、ここでは粒子として表面が疎水性のもの、有機溶剤として疎水性のものを選択し、下層液として親水性のものを使用する例を示したが、粒子として表面が親水性のもの、有機溶剤として親水性のものを選択し、下層液として疎水性の液体を使用してもよい。
　以下に、使用する分散液および各工程について具体的に説明する。 In the single particle film disposing step by LB method, for example, a water tank (trough) containing water as a liquid (hereinafter sometimes referred to as a lower layer liquid) for developing particles on the liquid surface is prepared, and the liquid Step of dropping a dispersion in which particles are dispersed in an organic solvent having a smaller specific gravity than water on a surface (dropping step) and step of forming a single particle film composed of particles by volatilizing the organic solvent (single particle A film formation process can be implemented by the method including the process (transfer process) which transfers the formed single particle film to a negative | original plate. After the transfer step, a step (fixing step) of fixing the single particle film transferred to the substrate to the substrate may be performed.
At this time, particles having a hydrophobic surface are used as the particles so that the particles do not dip below the surface of the hydrophilic lower layer liquid. Also, as the organic solvent, a hydrophobic solvent is selected so that when the dispersion is dropped onto the liquid surface of the lower layer liquid, the dispersion will expand to the air-liquid interface of the air and the lower layer liquid without mixing with the lower layer liquid. Be done.
In this example, the particles having a hydrophobic surface and the organic solvent having a hydrophobic surface are selected, and the lower layer liquid is hydrophilic, but the particles having a hydrophilic surface and an organic solvent are used. A hydrophilic solvent may be selected, and a hydrophobic liquid may be used as the lower layer liquid.
The dispersion to be used and each step will be specifically described below.
「分散液」
　分散液に用いる有機溶剤は、水よりも比重が小さい疎水性のものである。該有機溶剤はまた、高い揮発性を有することも重要である。水よりも比重が小さく疎水性であり、高い揮発性を有する有機溶剤としては、例えば、クロロホルム、メタノール（混合用材として使用）、エタノール（混合用材として使用）、イソプロパノール（混合用材として使用）、アセトン（混合用材として使用）、メチルエチルケトン、ジエチルケトン、トルエン、ヘキサン、シクロヘキサン、酢酸エチル、酢酸ブチル等の１種以上からなる揮発性有機溶剤が挙げられる。 "Dispersion liquid"
The organic solvent used for the dispersion is a hydrophobic one having a smaller specific gravity than water. It is also important that the organic solvent have high volatility. Examples of organic solvents having a specific gravity smaller than water and being hydrophobic and having high volatility include chloroform, methanol (used as a material for mixing), ethanol (used as a material for mixing), isopropanol (used as a material for mixing), acetone (Used as a material for mixing) Volatile organic solvents comprising one or more kinds of methyl ethyl ketone, diethyl ketone, toluene, hexane, cyclohexane, ethyl acetate, butyl acetate and the like.
　表面が疎水性の粒子としては、先に例示した粒子のうち、ポリスチレン等の有機材料からなり表面が元々疎水性を示すものを使用してもよく、表面が親水性の粒子を疎水化剤で疎水性にしたものを使用してもよい。
　疎水化剤としては、例えば界面活性剤、金属アルコキシド等が使用できる。
　界面活性剤を疎水化剤として使用する方法は、幅広い材料の疎水化に有効であり、粒子が無機酸化物等からなる場合に好適である。
　金属アルコキシドを疎水化剤として使用する方法は、酸化アルミニウム、酸化ケイ素、酸化チタン等の無機酸化物粒子を疎水化する際に有効である。また、無機酸化物粒子以外にも、表面に水酸基を有する粒子に対して適用することができる。 Among the particles exemplified above, particles having an organic material such as polystyrene and having an originally hydrophobic surface may be used as the particles having a hydrophobic surface, and the particles having a hydrophilic surface are treated with a hydrophobicizing agent. You may use what was made hydrophobic.
As the hydrophobizing agent, for example, surfactants, metal alkoxides and the like can be used.
The method of using a surfactant as a hydrophobizing agent is effective for hydrophobization of a wide range of materials, and is suitable when the particles are made of an inorganic oxide or the like.
The method of using a metal alkoxide as a hydrophobizing agent is effective in hydrophobizing inorganic oxide particles such as aluminum oxide, silicon oxide and titanium oxide. In addition to inorganic oxide particles, the present invention can be applied to particles having a hydroxyl group on the surface.
　界面活性剤としては、臭素化ヘキサデシルトリメチルアンモニウム、臭素化デシルトリメチルアンモニウム等のカチオン性界面活性剤、ドデシル硫酸ナトリウム、４－オクチルベンゼンスルホン酸ナトリウム等のアニオン性界面活性剤が好適に使用できる。また、アルカンチオール、ジスルフィド化合物、テトラデカン酸、オクタデカン酸等も使用できる。 As the surfactant, cationic surfactants such as hexadecyltrimethylammonium bromide and decyltrimethylammonium bromide, and anionic surfactants such as sodium dodecyl sulfate and sodium 4-octylbenzene sulfonate can be suitably used. Also, alkanethiols, disulfide compounds, tetradecanoic acid, octadecanoic acid and the like can be used.
　金属アルコキシドとしては、例えばアルコキシシランが挙げられる。
　アルコキシシランとしては、モノメチルトリメトキシシラン、モノメチルトリエトキシシラン、ジメチルジエトキシシラン、フェニルトリエトキシシラン、ヘキシルトリメトキシシラン、デシルトリメトキシシラン、ビニルトリクロルシラン、ビニルトリメトキシシラン、ビニルトリエトキシシラン、２－（３，４－エポキシシクロヘキシル）エチルトリメトキシシラン、３－グリシドキシプロピルトリメトキシシラン、３－グリシドキシプロピルメチルジエトキシシラン、３－グリシドキシプロピルトリエトキシシラン、ｐ－スチリルトリメトキシシラン、３－メタクリロキシプロピルメチルジメトキシシラン、３－メタクリロキシプロピルトリメトキシシラン、３－メタクリロキシプロピルメチルジエトキシシラン、３－メタクリロキシプロピルトリエトキシシラン、３－アクリロキシプロピルトリメトキシシラン、Ｎ－２（アミノエチル）３－アミノプロピルメチルジメトキシシラン、Ｎ－２（アミノエチル）３－アミノプロピルトリメトキシシラン、Ｎ－２（アミノエチル）３－アミノプロピルトリエトキシシラン、３－アミノプロピルトリメトキシシラン、３－アミノプロピルトリエトキシシラン、Ｎ－フェニル－３－アミノプロピルトリメトキシシラン、３－ウレイドプロピルトリエトキシシラン、３－クロロプロピルトリメトキシシラン、３－メルカプトプロピルメチルジメトキシシラン、３－メルカプトプロピルトリメトキシシラン、３－イソシアネートプロピルトリエトキシシラン等が挙げられる。 As a metal alkoxide, an alkoxysilane is mentioned, for example.
As the alkoxysilane, monomethyltrimethoxysilane, monomethyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2 -(3,4-Epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane Silane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxy Ropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane, N-2 (amino Ethyl) 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-chloropropyl Examples thereof include trimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane and the like.
　界面活性剤を用いた疎水化処理は、有機溶剤や水等の液体に粒子を分散させて液中で行ってもよいし、乾燥状態にある粒子に対して行ってもよい。
　液中で行う場合には、例えば、前述の揮発性有機溶剤中に、疎水化対象の粒子を加えて分散させ、その後、界面活性剤を混合してさらに分散を続ければよい。このようにあらかじめ粒子を分散させておき、それから界面活性剤を加えると、表面をより均一に疎水化することができる。このような疎水化処理後の分散液は、そのまま、滴下工程において下層液の液面に滴下するための分散液として使用できる。
　疎水化対象の粒子が水分散体の状態である場合には、この水分散体に界面活性剤を加えて水相で粒子表面の疎水化処理を行った後、有機溶剤を加えて疎水化処理済みの粒子を油相抽出する方法も有効である。こうして得られた分散液（有機溶剤中に粒子が分散した分散液）は、そのまま、滴下工程において下層液の液面に滴下するための分散液として使用できる。
　分散液の粒子分散性を高めるために、有機溶剤の種類と界面活性剤の種類とを適切に選択し、組み合わせることが好ましい。粒子分散性の高い分散液を使用することによって、粒子がクラスター状に凝集することを抑制でき、各粒子が二次元に密集した単粒子膜がより得られやすくなる。例えば、有機溶剤としてクロロホルムを選択する場合には、界面活性剤として臭素化デシルトリメチルアンモニウムを使用することが好ましい。その他にも、エタノールとドデシル硫酸ナトリウムとの組み合わせ、メタノールと４－オクチルベンゼンスルホン酸ナトリウムとの組み合わせ、メチルエチルケトンとオクタデカン酸との組み合わせ等を好ましく例示できる。
　疎水化対象の粒子と界面活性剤の比率は、疎水化対象の粒子の質量に対して、界面活性剤の質量が１／３～１／１５倍の範囲が好ましい。
　こうした疎水化処理の際には、処理中の分散液を撹拌したり、分散液に超音波照射したりすることも粒子分散性向上の点で効果的である。 The hydrophobization treatment using a surfactant may be carried out by dispersing particles in a liquid such as an organic solvent or water, and may be carried out on particles in a dry state.
When it is carried out in a liquid, for example, particles to be hydrophobized may be added and dispersed in the above-mentioned volatile organic solvent, and then the surfactant may be mixed and dispersion may be continued. By dispersing particles in this manner and then adding a surfactant, the surface can be made more uniformly hydrophobic. The dispersion after such hydrophobization treatment can be used as it is as a dispersion for dropping onto the liquid surface of the lower layer liquid in the dropping step.
When the particles to be hydrophobized are in the form of an aqueous dispersion, a surfactant is added to the aqueous dispersion to perform hydrophobization on the particle surface in the aqueous phase, and then an organic solvent is added to hydrophobize. The method of oil phase extraction of the finished particles is also effective. The dispersion (dispersion in which the particles are dispersed in the organic solvent) thus obtained can be used as it is as a dispersion to be dropped onto the liquid surface of the lower layer liquid in the dropping step.
In order to increase the particle dispersibility of the dispersion, it is preferable to appropriately select and combine the type of organic solvent and the type of surfactant. By using a dispersion having high particle dispersibility, it is possible to suppress aggregation of particles in the form of clusters, and it becomes easier to obtain a single particle film in which each particle is densely packed in two dimensions. For example, when chloroform is selected as the organic solvent, it is preferable to use decyltrimethylammonium bromide as the surfactant. Besides, a combination of ethanol and sodium dodecyl sulfate, a combination of methanol and sodium 4-octylbenzene sulfonate, a combination of methyl ethyl ketone and octadecanoic acid, and the like can be preferably exemplified.
The ratio of the particles to be hydrophobized to the surfactant is preferably such that the mass of the surfactant is 1/3 to 1/15 times the mass of the particles to be hydrophobized.
In the case of such hydrophobization treatment, it is also effective to stir the dispersion during treatment or to irradiate the dispersion with ultrasonic waves in terms of improvement of the particle dispersibility.
　金属アルコキシドを用いた疎水化処理では、金属アルコキシド中の金属原子に結合したアルコキシ基が加水分解し、水酸基が生成する。例えばアルコキシシランの場合、アルコキシシリル基が加水分解してシラノール基（Ｓｉ－ＯＨ）が生成する。生成した水酸基が粒子表面の水酸基と脱水縮合することで疎水化が行われる。よって、金属アルコキシドを用いた疎水化処理は、水中で実施することが好ましい。このように水中で疎水化処理を行う場合には、例えば界面活性剤等の分散剤を併用して、疎水化前の粒子の分散状態を安定化するのが好ましいが、分散剤の種類によっては金属アルコキシドの疎水化効果が低減することもあるため、分散剤と金属アルコキシドとの組み合わせは適切に選択する。 In the hydrophobization treatment using a metal alkoxide, the alkoxy group bonded to the metal atom in the metal alkoxide is hydrolyzed to form a hydroxyl group. For example, in the case of alkoxysilane, the alkoxysilyl group is hydrolyzed to form a silanol group (Si-OH). Hydrophobization is performed by dehydrating condensation of the generated hydroxyl groups with hydroxyl groups on the particle surface. Therefore, it is preferable to carry out the hydrophobization treatment using a metal alkoxide in water. When the hydrophobization treatment is carried out in water as described above, it is preferable to stabilize the dispersion state of the particles before hydrophobization by using, for example, a dispersing agent such as a surfactant, depending on the kind of the dispersing agent. Since the hydrophobization effect of the metal alkoxide may be reduced, the combination of the dispersant and the metal alkoxide is appropriately selected.
　金属アルコキシドにより粒子を疎水化する具体的方法としては、まず、水中に粒子を分散させておき、これと金属アルコキシド含有水溶液（金属アルコキシドの加水分解物を含む水溶液）とを混合し、室温から４０℃の範囲で適宜攪拌しながら所定時間、好ましくは６～１２時間反応させる。このような条件で反応させることによって、反応が適度に進行し、十分に疎水化された粒子の分散液を得ることができる。反応が過度に進行すると、シラノール基同士が反応して粒子同士が結合してしまい、分散液の粒子分散性が低下し、得られる単粒子膜は、粒子が部分的にクラスター状に凝集した２層以上のものになりやすい。一方、反応が不十分であると、粒子表面の疎水化も不十分となり、後述する粒子を水面に展開する操作において粒子が水中に沈降する不具合が生じたり、得られる単粒子膜の強度が低下してシワ状の欠陥が生じたりするため好ましくない。
　前述のアルコキシシランのうちアミン系以外のアルコキシシランは、酸性又はアルカリ性の条件下で加水分解するため、反応時には分散液のｐＨを酸性又はアルカリ性に調整する必要がある。ｐＨの調整法には制限はないが、０．１～２．０質量％濃度の酢酸水溶液を添加する方法によれば、加水分解促進の他に、シラノール基安定化の効果も得られるため好ましい。
　疎水化対象の粒子と金属アルコキシドの比率は、疎水化対象の粒子の質量に対して、金属アルコキシドの質量が１／３～１／１００倍の範囲が好ましい。
　所定時間反応後、この分散液に対して、前述の揮発性有機溶剤のうちの１種以上を加え、水中で疎水化された粒子を油相抽出する。この際、添加する有機溶剤の体積は、有機溶剤添加前の分散液に対して０．３～３倍の範囲が好ましい。こうして得られた分散液（有機溶剤中に粒子が分散した分散液）は、そのまま、滴下工程において下層液の液面に滴下するための分散液として使用できる。
　こうした疎水化処理においては、処理中の分散液の粒子分散性を高めるために、撹拌、超音波照射等実施することが好ましい。分散液の粒子分散性を高めることによって、粒子がクラスター状に凝集することを抑制でき、各粒子が二次元に密集した単粒子膜がより得られやすくなる。 As a specific method of hydrophobizing particles with metal alkoxide, first, the particles are dispersed in water, and this is mixed with a metal alkoxide-containing aqueous solution (an aqueous solution containing a hydrolyzate of metal alkoxide), The reaction is carried out for a predetermined time, preferably 6 to 12 hours, with appropriate stirring in the range of ° C. By conducting the reaction under such conditions, the reaction proceeds moderately, and a dispersion liquid of sufficiently hydrophobized particles can be obtained. When the reaction proceeds excessively, the silanol groups react with each other to combine the particles with each other, the particle dispersibility of the dispersion decreases, and in the obtained single particle film, the particles partially aggregate in a cluster 2 It is easy to become more than a layer. On the other hand, if the reaction is insufficient, the hydrophobicization of the particle surface also becomes insufficient, and in the operation of developing the particles to be described later on the water surface, problems occur that the particles settle in water, or the strength of the obtained single particle film decreases. It is not preferable because wrinkle-like defects occur.
Among the above-mentioned alkoxysilanes, since the alkoxysilanes other than amine based hydrolyze under acidic or alkaline conditions, it is necessary to adjust the pH of the dispersion to be acidic or alkaline during the reaction. There is no limitation on the method of adjusting the pH, but according to the method of adding an aqueous acetic acid solution having a concentration of 0.1 to 2.0% by mass, in addition to the promotion of hydrolysis, the effect of stabilizing the silanol group is also obtained. .
The ratio of the particles to be hydrophobized to the metal alkoxide is preferably such that the mass of the metal alkoxide is 1/3 to 1/100 times the mass of the particles to be hydrophobized.
After the reaction for a predetermined time, one or more of the above-mentioned volatile organic solvents are added to the dispersion, and the oil-phase extracted particles made hydrophobic in water. At this time, the volume of the organic solvent to be added is preferably 0.3 to 3 times the volume of the dispersion before addition of the organic solvent. The dispersion (dispersion in which the particles are dispersed in the organic solvent) thus obtained can be used as it is as a dispersion to be dropped onto the liquid surface of the lower layer liquid in the dropping step.
In such hydrophobization treatment, in order to enhance the particle dispersibility of the dispersion during treatment, it is preferable to carry out stirring, ultrasonic irradiation and the like. By enhancing the particle dispersibility of the dispersion, it is possible to suppress aggregation of the particles in the form of clusters, and it becomes easier to obtain a single particle film in which each particle is two-dimensionally dense.
「滴下工程」
　滴下工程では、上記の分散液を、下層液の液面に滴下する。
　下層液に滴下する分散液中の粒子の濃度は１～１０質量％とすることが好ましい。また、分散液の滴下速度を０．００１～０．０１ｍＬ／秒とすることが好ましい。分散液中の粒子の濃度や分散液の滴下量がこのような範囲であると、粒子が部分的にクラスター状に凝集して２層以上となる、粒子が存在しない欠陥箇所が生じる、粒子間のピッチが広がる等の傾向が抑制され、各粒子が二次元に密集した単粒子膜がより得られやすい。 "Dropping process"
In the dropping step, the above dispersion liquid is dropped onto the liquid surface of the lower layer liquid.
The concentration of particles in the dispersion to be dropped to the lower layer solution is preferably 1 to 10% by mass. In addition, the dropping speed of the dispersion is preferably 0.001 to 0.01 mL / sec. When the concentration of particles in the dispersion and the dropping amount of the dispersion are in such a range, the particles partially aggregate in a cluster shape to form two or more layers, causing a defect location where no particles exist, interparticle The tendency of the pitch to spread is suppressed, and a single particle film in which each particle is densely packed in two dimensions is more easily obtained.
　形成する単粒子膜の精度をより高めるために、液面に滴下する前の分散液をメンブランフィルター等で精密ろ過して、分散液中に存在する凝集粒子（複数の一次粒子からなる二次粒子）を除去することが好ましい。このようにあらかじめ精密ろ過を行っておくと、部分的に２層以上となった箇所や、粒子が存在しない欠陥箇所が生じにくく、精度の高い単粒子膜が得られやすい。仮に、形成された単粒子膜に、数～数十μｍ程度の大きさの欠陥箇所が存在したとすると、詳しくは後述する移行工程において、単粒子膜の表面圧を計測する表面圧力センサーと、単粒子膜を液面方向に圧縮する可動バリアとを備えたＬＢトラフ装置を使用したとしても、このような欠陥箇所は表面圧の差として検知されず、高精度な単粒子膜を得ることは難しくなる。 In order to further enhance the accuracy of the single particle membrane to be formed, the dispersion before dropping onto the liquid surface is precision filtered with a membrane filter or the like, and aggregated particles (secondary particles consisting of a plurality of primary particles) present in the dispersion Is preferred to be removed. Thus, if precision filtration is performed in advance, it is hard to produce the location which became two or more layers partially, the defect location which particle | grains do not exist, and it is easy to obtain a highly accurate single particle film. Assuming that a defect portion having a size of several to several tens of μm exists in the formed single particle film, a surface pressure sensor that measures the surface pressure of the single particle film in the transition step described in detail later; Even if an LB trough apparatus provided with a movable barrier that compresses a single particle film in the liquid surface direction is used, such a defect is not detected as a difference in surface pressure, and a high accuracy single particle film can be obtained. It becomes difficult.
「単粒子膜形成工程」
　滴下工程において分散液を下層液の液面に滴下すると、分散媒である溶剤が揮発するとともに、粒子が下層液の液面上に単層で展開し、粒子が二次元に密集した単粒子膜を形成することができる。 "Single particle film formation process"
When the dispersion liquid is dropped onto the liquid surface of the lower layer liquid in the dropping step, the solvent as the dispersion medium is volatilized, and the particles are spread in a single layer on the liquid surface of the lower liquid layer, and the particles are two-dimensionally dense Can be formed.
　この単粒子膜の形成は、粒子の自己組織化によるものである。その原理は、粒子が集結すると、粒子間に存在する分散媒に起因して表面張力が作用し、その結果、粒子同士はバラバラの状態で存在するのではなく、下層液の液面上で密集した単層構造を自動的に形成するというものである。このような表面張力による単層構造の形成は、別の表現をすると横方向の毛細管力による粒子同士の相互吸着ともいえる。例えば、同じ粒子径の３つの球状粒子が水面上に浮いた状態で集まり接触すると、粒子群の喫水線の合計長を最小にするように表面張力が作用し、３つの粒子は正三角形を基本とする配置で安定化する。仮に、喫水線が粒子群の頂点にくる場合、すなわち、粒子が液面下に潜ってしまう場合には、このような自己組織化は起こらず、単粒子膜は形成されない。よって、粒子と下層液は、一方が疎水性である場合には他方を親水性にして、粒子群が液面下に潜ってしまわないようにすることが重要である。
　下層液としては、以上の説明のように水を使用することが好ましく、水を使用すると、比較的大きな表面自由エネルギーが作用して、一旦生成した粒子の密集した単層構造が液面上に安定的に持続しやすくなる。 The formation of this single particle film is due to the self-organization of the particles. The principle is that when particles are concentrated, surface tension acts due to the dispersion medium present between the particles, and as a result, the particles are not separated from each other, but are concentrated on the liquid surface of the lower layer liquid Automatically forms a single layer structure. In other words, the formation of a single layer structure by such surface tension can be said to be mutual adsorption of particles due to the lateral capillary force. For example, when three spherical particles of the same particle size float and gather on the water surface and contact each other, surface tension acts to minimize the total length of the waterline of the particle group, and the three particles are based on an equilateral triangle. Stabilize in place. If the waterline is at the top of the particle group, that is, if the particle dives below the liquid surface, such self-organization does not occur and a monoparticle film is not formed. Therefore, it is important to make the particles and the lower layer liquid hydrophilic if one is hydrophobic so that the particle group does not dip below the liquid surface.
As the lower layer liquid, it is preferable to use water as described above, and when water is used, relatively large surface free energy acts to form a dense single layer structure of particles once generated on the liquid surface. It becomes stable and easy to sustain.
　単粒子膜形成工程は、超音波照射条件下で実施することが好ましい。下層液から水面に向けて超音波を照射しながら単粒子膜形成工程を行うと、粒子同士の相互吸着が促進され、各粒子がより高精度に二次元に密集した単粒子膜が得られる。
　この際、超音波の出力は１～１２００Ｗが好ましく、５０～６００Ｗがより好ましい。
　超音波の周波数には特に制限はないが、例えば２８ｋＨｚ～５ＭＨｚが好ましく、７００ｋＨｚ～２ＭＨｚがより好ましい。振動数が高すぎると、水分子のエネルギー吸収が始まり、水面から水蒸気又は水滴が立ち上る現象が起きるため、ＬＢ法にとって好ましくない。振動数が低すぎると、下層液中のキャビテーション半径が大きくなり、水中に泡が発生して水面に向かって浮上してくる。このような泡が単粒子膜の下に集積すると、水面の平坦性が失われるためＬＢ法にとって不都合となる。
　超音波照射を行うと、水面に定常波が発生する。いずれの周波数でも出力が高すぎたり、超音波振動子と発信機のチューニング条件によって水面の波高が高くなりすぎたりすると、単粒子膜が水面波で破壊されるため気をつける必要がある。 The single particle film forming step is preferably performed under ultrasonic irradiation conditions. When the single particle film forming step is performed while irradiating ultrasonic waves from the lower layer solution to the water surface, mutual adsorption of particles is promoted, and a single particle film in which each particle is densely packed in two dimensions can be obtained.
At this time, the output of the ultrasonic wave is preferably 1 to 1200 W, more preferably 50 to 600 W.
The frequency of ultrasonic waves is not particularly limited, but for example, 28 kHz to 5 MHz is preferable, and 700 kHz to 2 MHz is more preferable. If the frequency is too high, energy absorption of water molecules starts, and a phenomenon that water vapor or water droplets rise from the water surface occurs, which is not preferable for the LB method. If the frequency is too low, the cavitation radius in the lower layer solution will be large, and bubbles will be generated in the water and will rise toward the water surface. When such bubbles accumulate under the monoparticle film, the flatness of the water surface is lost, which is disadvantageous for the LB method.
When ultrasonic waves are applied, standing waves are generated on the water surface. If the output is too high at any frequency, or if the wave height of the water surface is too high due to the tuning conditions of the ultrasonic transducer and the transmitter, the single particle film is broken by the water wave, so care must be taken.
　以上のことに留意して超音波の周波数を適切に設定すると、形成されつつある単粒子膜を破壊することなく、効果的に粒子の密集を促進することができる。効果的な超音波照射を行うためには、粒子の粒子径から計算される固有振動数を目安にするのが良い。しかし、粒子径が例えば１００ｎｍ以下等小さな粒子になると固有振動数は非常に高くなってしまうため、計算結果のとおりの超音波振動を与えるのは困難になる。このような場合は、粒子の２量体～２０量体程度までの質量に対応する固有振動を与えると仮定して計算を行うと、必要な振動数を現実的な範囲まで低減させることが出来る。粒子の会合体の固有振動数に対応する超音波振動を与えた場合でも、粒子の充填率向上効果は発現する。超音波の照射時間は、粒子の再配列が完了するのに十分であればよく、粒子径、超音波の周波数、水温等によって所要時間が変化する。しかし通常の作成条件では１０秒間～６０分間で行うのが好ましく、より好ましくは３分間～３０分間である。
　超音波照射によって得られる利点は、粒子の高精度の密集化の他に、ナノ粒子分散液調製時に発生しやすい粒子の軟凝集体を破壊する効果、一度発生した点欠陥、線欠陥、又は結晶転移等をある程度修復する効果等がある。 If the frequency of ultrasonic waves is set appropriately in consideration of the above, it is possible to effectively promote the concentration of particles without destroying the monoparticle film being formed. In order to perform effective ultrasonic wave irradiation, it is good to use the natural frequency calculated from the particle diameter of particles as a standard. However, when the particle size is small, for example, 100 nm or less, the natural frequency becomes very high, and it becomes difficult to give ultrasonic vibration as calculated. In such a case, it is possible to reduce the necessary frequency to a realistic range by performing calculations assuming that the natural vibration corresponding to the mass from the particle dimer to about 20 mer is given. . Even when ultrasonic vibration corresponding to the natural frequency of the aggregate of particles is given, the effect of improving the packing ratio of particles is exhibited. The irradiation time of the ultrasonic waves may be sufficient to complete the rearrangement of the particles, and the required time changes depending on the particle diameter, the frequency of the ultrasonic waves, the water temperature, and the like. However, under normal preparation conditions, it is preferably performed for 10 seconds to 60 minutes, more preferably for 3 minutes to 30 minutes.
The advantages obtained by the ultrasonic irradiation include the effect of destroying the soft agglomerates of particles that are easily generated during preparation of the nanoparticle dispersion, point defects, line defects, or crystals that are easily generated during preparation of the nanoparticle dispersion, in addition to high-density packing of particles. There is an effect of repairing the metastasis etc. to some extent.
「移行工程」
　移行工程では、単粒子膜形成工程により液面上に形成された単粒子膜を、単層状態のまま原板上に移し取る。
　原板は、表面に二次元格子構造が形成されていない以外は基板１と同様である。
　単粒子膜を原板上に移し取る具体的な方法には特に制限はなく、例えば、疎水性の原板を単粒子膜に対して略平行な状態に保ちつつ、上方から降下させて単粒子膜に接触させ、ともに疎水性である単粒子膜と原板との親和力により、単粒子膜を原板に吸着移行させ、移し取る方法；単粒子膜を形成する前にあらかじめ水槽の下層液内に原板を略水平方向に配置しておき、単粒子膜を液面上に形成した後に液面を徐々に降下させることにより、原板上に単粒子膜を移し取る方法；等がある。
　これらの方法によれば、特別な装置を使用せずに単粒子膜を原板上に移し取ることができるが、より大面積の単粒子膜であっても、複数の粒子が二次元に密集した単層膜の状態を維持したまま原板上に移し取りやすい点で、いわゆるＬＢトラフ法を採用することが好ましい（Journal of Materials and Chemistry, Vol.11, 3333 (2001)、Journal of Materials and Chemistry, Vol.12, 3268 (2002)等参照。）。 "Migration process"
In the transfer step, the single particle film formed on the liquid surface in the single particle film forming step is transferred onto the original plate in a single layer state.
The original plate is the same as the substrate 1 except that the two-dimensional lattice structure is not formed on the surface.
There is no particular limitation on the specific method of transferring the monoparticle film onto the original plate, and for example, the hydrophobic original plate is lowered from above while being kept substantially parallel to the single particle membrane to form a single particle membrane. Method of adsorbing and transferring the single particle film to the original plate by contact and affinity between the single particle film and the original plate both being hydrophobic; transferring the original plate in advance to the lower layer liquid of the water tank before forming the single particle film There is a method of transferring the single particle film onto the original plate by arranging the particles in the horizontal direction and forming the single particle film on the liquid surface and then gradually lowering the liquid surface.
According to these methods, the single particle film can be transferred onto the original plate without using a special device, but even with a larger area single particle film, a plurality of particles are densely packed in two dimensions. It is preferable to adopt the so-called LB trough method in that it is easily transferred onto the original plate while maintaining the state of the monolayer film (Journal of Materials and Chemistry, Vol. 11, 3333 (2001), Journal of Materials and Chemistry, Vol. 12, 3268 (2002), etc.).
　ＬＢトラフ法では、水槽内の下層液に原板をあらかじめ略鉛直方向に浸漬しておき、その状態で上述の滴下工程と単粒子膜形成工程とを行い、単粒子膜を形成する。そして、単粒子膜形成工程後に、原板を上方に引き上げることによって、単粒子膜を原板上に移し取ることができる。
　単粒子膜は、単粒子膜形成工程により下層液の液面上ですでに単層の状態に形成されているため、移行工程の温度条件（下層液の温度）や原板の引き上げ速度等が多少変動しても、移行工程において単粒子膜が崩壊して多層化する等のおそれはない。なお、下層液の温度は、通常、季節や天気により変動する環境温度に依存し、ほぼ３～３０℃程度である。
　この際、水槽として、単粒子膜の表面圧を計測するウィルヘルミープレート等を原理とする表面圧力センサーと、単粒子膜を液面に沿う方向に圧縮する可動バリアとを具備するＬＢトラフ装置を使用すると、より大面積の単粒子膜をより安定に原板上に移し取ることができる。このような装置によれば、単粒子膜の表面圧を計測しながら、単粒子膜を好ましい拡散圧（密度）に圧縮でき、また、基板の方に向けて一定の速度で移動させることができる。そのため、単粒子膜の液面から原板上への移行が円滑に進行し、小面積の単粒子膜しか原板上に移行できない等のトラブルが生じにくい。
　好ましい拡散圧は５～８０ｍＮｍ－１であり、より好ましくは３～４０ｍＮｍ－１である。このような拡散圧であると、各粒子がより高精度で二次元に密集した単粒子膜が得られやすい。原板を引き上げる速度は、０．５～２０ｍｍ／分が好ましい。なお、ＬＢトラフ装置は、市販品として入手することができる。 In the LB trough method, an original plate is dipped in a substantially vertical direction in a lower layer solution in a water tank in advance, and the dropping step and the single particle film forming step described above are performed in this state to form a single particle film. Then, after the single particle film forming step, the single particle film can be transferred onto the original plate by pulling the original plate upward.
Since the single particle film is already formed in a single layer state on the liquid surface of the lower layer liquid in the single particle film forming step, the temperature condition of the transfer step (the temperature of the lower layer liquid) and the pulling speed of the original plate are somewhat Even if it fluctuates, there is no fear that the single particle film collapses and becomes multilayered in the transfer step. The temperature of the lower layer liquid is usually about 3 to 30 ° C., depending on the environmental temperature which fluctuates depending on the season and the weather.
At this time, an LB trough apparatus including a surface pressure sensor based on a Wilhelmy plate or the like for measuring the surface pressure of a single particle film as a water tank and a movable barrier for compressing the single particle film in the direction along the liquid surface. Can be used to more stably transfer a large-area single particle membrane onto the original plate. According to such an apparatus, the single particle film can be compressed to a preferable diffusion pressure (density) while measuring the surface pressure of the single particle film, and can be moved at a constant speed toward the substrate. . Therefore, the transition from the liquid surface of the single particle membrane to the original plate smoothly proceeds, and troubles such as only the small particle single particle membrane of the small area can be transferred onto the original plate hardly occur.
The preferred diffusion pressure is 5 to 80 mNm -1 , more preferably 3 to 40 mNm -1 . With such a diffusion pressure, it is easy to obtain a single particle film in which each particle is densely packed two-dimensionally. The speed of pulling up the original plate is preferably 0.5 to 20 mm / min. The LB trough apparatus can be obtained as a commercial product.
「固定工程」
　移行工程で原板上に移行させた単粒子膜を原板に固定する固定工程を行うことで、後述のドライエッチング工程中に、単粒子膜を構成する粒子が原板の表面を移動したり単粒子膜が剥がれたりすることを抑制でき、より安定かつ高精度に原板をエッチングすることができる。
　固定工程の方法としては、バインダーを使用する方法や焼結法が挙げられる。
　バインダーを使用する方法では、バインダー溶液を、単粒子膜が形成された原板の表面に供給し、単粒子膜を構成する粒子と原板との間に浸透させる。
　バインダーとしては、先に疎水化剤として例示した金属アルコキシドや一般の有機バインダー、無機バインダー等を使用できる。
　バインダーの使用量は、単粒子膜の質量の０．００１～０．０２質量倍が好ましい。このような範囲であれば、バインダーが多すぎて粒子間にバインダーが詰まってしまい、単粒子膜の精度に悪影響を与えるという問題を生じることなく、十分に粒子を固定することができる。バインダー溶液を多く供給してしまった場合には、バインダー溶液が浸透した後に、スピンコーターを使用したり、原板を傾けたりして、バインダー溶液の余剰分を除去すればよい。
　バインダー溶液が浸透した後には、バインダーの種類に応じて、適宜加熱処理を行えばよい。金属アルコキシドをバインダーとして使用する場合には、４０～８０℃で３～６０分間の条件で加熱処理することが好ましい。 "Fixing process"
By performing the fixing step of fixing the single particle film transferred onto the original plate in the transfer step to the original plate, the particles constituting the single particle film move on the surface of the original plate during the dry etching step described later. Can be suppressed, and the original plate can be etched more stably and accurately.
As a method of a fixing process, the method of using a binder, and the sintering method are mentioned.
In the method of using a binder, a binder solution is supplied to the surface of the original plate on which the single particle film is formed, and is made to permeate between the particles constituting the single particle film and the original plate.
As the binder, the metal alkoxide exemplified as the hydrophobizing agent, a general organic binder, an inorganic binder and the like can be used.
The amount of binder used is preferably 0.001 to 0.02 mass times the mass of the single particle film. In such a range, the particles can be sufficiently fixed without causing a problem that the binder is too much and the binder is clogged between particles, which adversely affects the accuracy of the single particle film. If a large amount of binder solution has been supplied, the binder solution may be removed by using a spin coater or tilting the original plate after the binder solution has penetrated.
After the binder solution has penetrated, heat treatment may be appropriately performed according to the type of the binder. When a metal alkoxide is used as a binder, heat treatment is preferably performed at 40 to 80 ° C. for 3 to 60 minutes.
　焼結法を採用する場合には、単粒子膜が形成された原板を加熱して、単粒子膜を構成している各粒子を原板に融着させればよい。
　加熱温度は、粒子の材質および原板の材質に応じて決定すればよい。粒子径が１μｍ以下の粒子の場合は、粒子を構成する材料本来の融点よりも低い温度で界面反応を開始するため、比較的低温側で焼結は完了する。加熱温度が高すぎると、粒子の融着面積が大きくなり、その結果、単粒子膜の形状が変化する等、精度に影響を与える可能性がある。
　加熱を空気中で行うと、材質によっては、原板や粒子が酸化する可能性がある。例えば、原板としてシリコン基板を用い、これを１１００℃で焼結すると、この基板の表面には約２００ｎｍの厚さで熱酸化層が形成される。そのため、後述のドライエッチング工程では、このような酸化の可能性を考慮して、エッチング条件を設定することが必要となる。 In the case of employing the sintering method, the original plate on which the single particle film is formed may be heated to fuse the particles constituting the single particle film to the original plate.
The heating temperature may be determined according to the material of the particles and the material of the original plate. In the case of particles having a particle diameter of 1 μm or less, the interfacial reaction is initiated at a temperature lower than the melting point inherent to the material constituting the particles, so sintering is completed at a relatively low temperature side. When the heating temperature is too high, the fused area of the particles becomes large, and as a result, the shape of the single particle film may be changed, which may affect the accuracy.
When the heating is performed in air, depending on the material, the original plate and the particles may be oxidized. For example, when a silicon substrate is used as an original plate and this is sintered at 1100 ° C., a thermally oxidized layer is formed on the surface of this substrate with a thickness of about 200 nm. Therefore, in the dry etching process described later, it is necessary to set the etching conditions in consideration of the possibility of such oxidation.
　＜ドライエッチング工程＞
　ドライエッチング工程では、例えば、粒子と原板の双方が実質的にエッチングされる条件で、単粒子膜をエッチングマスクとして原板をドライエッチングする。
　このようにしてドライエッチングを行うと、単粒子膜を構成している各粒子がエッチングされ、各粒子の粒子径が徐々に小さくなり、ドライエッチング前は粒子同士が接していた部分にも隙間が形成され、粒子同士が接触していない状態になる。また、粒子間の隙間をエッチングガスが通り抜けて原板の表面に到達し、隙間の下方の位置にある原板表面がエッチングされて凹部が形成される。粒子で覆われている部分はエッチングされずに残り、この部分が凸部３ｃとなる。これにより、基板１が得られる。
　原板をドライエッチングする前に、原板が実質的にエッチングされない条件で、粒子をドライエッチングしてもよい。 <Dry etching process>
In the dry etching process, for example, the original plate is dry etched using the single particle film as an etching mask under the condition that both the particles and the original plate are substantially etched.
When dry etching is performed in this manner, each particle constituting the single particle film is etched, the particle diameter of each particle gradually decreases, and a gap is also formed in a portion where the particles are in contact with each other before dry etching. The particles are formed, and the particles are not in contact with each other. Further, the etching gas passes through the gaps between the particles to reach the surface of the original plate, and the surface of the original plate located below the gaps is etched to form a recess. The part covered with particles remains unetched, and this part becomes the convex 3c. Thereby, the substrate 1 is obtained.
Before dry etching the original plate, the particles may be dry etched under conditions that the original plate is not substantially etched.
　ドライエッチング条件、例えば圧力、プラズマ電力、バイアス電力、エッチングガス種、エッチングガス流量、エッチング時間等を調節することによって、凸部３ｃの太さ（表面層における占有体積：フィリングファクター）、凸部３ｃの高さ（凹部の深さ）等を調節できる。 By adjusting dry etching conditions such as pressure, plasma power, bias power, etching gas type, etching gas flow rate, etching time, etc., the thickness of the convex portion 3c (occupied volume in surface layer: filling factor), convex portion 3c Height (the depth of the recess) etc. can be adjusted.
　エッチングガスとしては、粒子および原板の両方をエッチングできるように、粒子や基板の材質等に応じて公知のエッチングガスのなかから適宜選択できる。
　例えば原板がガラスであり、粒子がシリカ（ＳｉＯ２）である場合、Ａｒ、ＳＦ６、Ｆ２、ＣＦ４、Ｃ４Ｆ８、Ｃ５Ｆ８、Ｃ２Ｆ６、Ｃ３Ｆ６、Ｃ４Ｆ６、ＣＨＦ３、ＣＨ２Ｆ２、ＣＨ３Ｆ、Ｃ３Ｆ８、Ｃｌ２、ＣＣｌ４、ＳｉＣｌ４、ＢＣｌ２、ＢＣｌ３、ＢＣ２、Ｂｒ２、Ｂｒ３、ＨＢｒ、ＣＢｒＦ３、ＨＣｌ、ＣＨ４、ＮＨ３、Ｏ２、Ｈ２、Ｎ２、ＣＯ、ＣＯ２等を使用できる。
　原板が石英で、粒子がシリカである場合、ＡｒやＣＦ４等を使用できる。
　原板がサファイアで、粒子がシリカである場合、Ｃｌ２、ＢＣｌ３、ＳｉＣｌ４、ＨＢｒ、ＨＩ、ＨＣｌ等を使用できる。
　エッチングガスは、１種を単独で用いてもよく２種以上を組み合わせて用いてもよい。２種以上のエッチングガスの混合比率等によってエッチング条件の調整が容易となる。
　エッチングガスは、エッチングガス以外のガスで希釈されてもよい。 The etching gas can be appropriately selected from known etching gases according to the material of the particles, the substrate, etc., so that both the particles and the original plate can be etched.
For example, when the original plate is glass and the particles are silica (SiO 2 ), Ar, SF 6 , F 2 , CF 4 , C 4 F 8 , C 5 F 8 , C 2 F 6 , C 3 F 6 , C 4 F 6 , CHF 3 , CH 2 F 2 , CH 3 F, C 3 F 8 , Cl 2 , CCl 4 , SiCl 4 , BCl 2 , BCl 3 , BC 2 , Br 2 , Br 3 , HBr, CBrF 3 , HCl, CH 4, NH 3, O 2, H 2, N 2, CO, and CO 2 and the like can be used.
When the original plate is quartz and the particles are silica, Ar or CF 4 can be used.
When the original plate is sapphire and the particles are silica, Cl 2 , BCl 3 , SiCl 4 , HBr, HI, HCl, etc. can be used.
The etching gas may be used alone or in combination of two or more. Adjustment of etching conditions is facilitated by the mixing ratio of two or more etching gases.
The etching gas may be diluted with a gas other than the etching gas.
　ドライエッチングは、原板の水平方向よりも垂直方向のエッチング速度が大きくなる異方性エッチングで行うことが好ましい。使用可能なエッチング装置としては、反応性イオンエッチング装置、イオンビームエッチング装置等の異方性エッチングが可能なものであって、最小で２０Ｗ程度のバイアス電場を発生できるものであれば、プラズマ発生の方式、電極の構造、チャンバーの構造、高周波電源の周波数等の仕様には特に制限ない。 The dry etching is preferably performed by anisotropic etching in which the etching rate in the vertical direction is larger than in the horizontal direction of the original plate. As a usable etching apparatus, it is possible to use anisotropic etching such as a reactive ion etching apparatus, an ion beam etching apparatus, etc., and generate a bias electric field of about 20 W at the minimum, it is possible to generate plasma There are no particular limitations on specifications such as the method, the structure of the electrode, the structure of the chamber, and the frequency of the high frequency power source.
　ドライエッチングにおけるエッチング選択比（原板のエッチング速度／単粒子膜のエッチング速度）は、特に制限されず、エッチングの各条件（単粒子膜を構成する粒子の材質、原板の材質、エッチングガスの種類、バイアス電力、アンテナ電力、ガス流量、圧力、エッチング時間等）により調整できる。 The etching selectivity in dry etching (etching rate of original plate / etching rate of single particle film) is not particularly limited, and each condition of etching (material of particles constituting single particle film, material of original plate, type of etching gas, The bias power, antenna power, gas flow rate, pressure, etching time, etc. can be adjusted.
　原板のドライエッチングは、単粒子膜を構成する粒子が消失したときに終了してもよく、該粒子が消失する前に終了してもよい。
　粒子が消失する前に原板のドライエッチングを終了した場合、原板のドライエッチングの後、形成された基板１上に残留する粒子を除去する。
　粒子の除去方法としては、粒子に対してエッチング性があり、基板１に対して耐エッチング性があるエッチャントを用いる化学的除去方法、ブラシロール洗浄機等による物理的除去方法等が挙げられる。 The dry etching of the original plate may be ended when the particles constituting the single particle film disappear, or may be ended before the particles disappear.
When the dry etching of the original plate is completed before the particles disappear, the particles remaining on the formed substrate 1 are removed after the dry etching of the original plate.
Examples of the method for removing particles include a chemical removal method using an etchant which is etchable to particles and etch resistant to the substrate 1, and a physical removal method using a brush roll cleaner or the like.
　上記のようにして、原版が得られる。
　原版の転写品は、原版表面の二次元格子構造を１回以上、他の原板に転写して得られる。転写回数が奇数回であると、原版表面の二次元格子構造が反転した形状の二次元格子構造を有する転写品が得られる。転写回数が偶数回であると、原版表面の二次元格子構造と同様の形状の二次元格子構造を有する転写品が得られる。
　例えば、原版表面の二次元格子構造を、モールド（金型又はスタンパー）に転写し（１回目の転写）、次いでモールドの二次元格子構造を転写する（２回目の転写）と、原版表面の二次元格子構造と同様の形状の二次元格子構造を有する転写品が得られる。
　原版の二次元格子構造を、モールド（金型又はスタンパー）に転写する方法は、例えば特開２００９－１５８４７８号公報に開示されているような電鋳法が好ましい。
　モールドの二次元格子構造を転写する方法としては、例えば特開２００９－１５８４７８号公報に開示されているような、ナノインプリント法、熱プレス法、射出成型法、ＵＶエンボス法等が挙げられる。中でもナノインプリント法は、微細な二次元格子構造の転写に適している。 The original plate is obtained as described above.
The transferred product of the original plate is obtained by transferring the two-dimensional lattice structure of the original plate surface to another original plate one or more times. When the number of times of transfer is an odd number, a transfer product having a two-dimensional lattice structure in which the two-dimensional lattice structure of the original plate surface is inverted is obtained. When the number of times of transfer is an even number, a transfer product having a two-dimensional lattice structure similar in shape to the two-dimensional lattice structure of the original plate surface is obtained.
For example, the two-dimensional lattice structure of the original plate surface is transferred to a mold (a mold or a stamper) (first transfer), and then the two-dimensional lattice structure of the mold is transferred (second transfer). A transfer product having a two-dimensional lattice structure of the same shape as the two-dimensional lattice structure is obtained.
As a method of transferring the two-dimensional lattice structure of the original plate to a mold (a mold or a stamper), for example, an electroforming method as disclosed in JP 2009-158478 A is preferable.
Examples of a method for transferring a two-dimensional lattice structure of a mold include a nanoimprinting method, a heat pressing method, an injection molding method, a UV embossing method, and the like as disclosed in JP-A-2009-158478. Above all, the nanoimprint method is suitable for the transfer of a fine two-dimensional lattice structure.
（作用効果）
　本実施形態の分析用基板１０にあっては、これを分光測定に用いたときに、金属膜３と金属ナノ粒子５との間、隣り合う金属ナノ粒子５の間それぞれにおいて入射光による局在型表面プラズモン共鳴が発生し、電場の重ねあわせによる非線形光学的電場増強効果を得ることができる。また連続膜である金属膜３の表面に二次元格子構造を有することで、伝搬型表面プラズモン共鳴による電場増強効果を得ることができる。２～３種の金属間隙における局在型表面プラズモン共鳴と１種の金属格子構造による伝搬型表面プラズモン共鳴とが組み合わさることで、電場増強効果を利用した光学的分析を高感度に実施できる。
　特に、金属膜３が態様Ａの金属膜３Ａである場合には、金属膜３の非成膜領域Ｇでも局在型表面プラズモン共鳴による電場増強を発生させることができ、電場増強を利用した光学的分析をより高感度に実施できる。
　分析用基板１０は生産性にも優れる。例えば、製造方法（Ｉ）に示したように、基板１Ｂ上に金属を堆積させ、さらに金属ナノ粒子分散液を塗布し乾燥するだけで製造できる。また、局在型表面プラズモン共鳴による電場増強を発生させ得る構造を形成するために多量の金属を用いる必要がなく、原料コストを抑制できる。
　上記効果を奏することから、分析用基板１０は、表面プラズモン共鳴による電場増強を利用した光学的分析に有用である。かかる光学的分析法としては、前記と同様のものが挙げられる。 (Action effect)
In the analysis substrate 10 of the present embodiment, when this is used for spectrometry, localization due to incident light between the metal film 3 and the metal nanoparticles 5 and between the adjacent metal nanoparticles 5 is made. Type surface plasmon resonance is generated, and it is possible to obtain a non-linear optical electric field enhancing effect by superposition of electric fields. Further, by having a two-dimensional lattice structure on the surface of the metal film 3 which is a continuous film, it is possible to obtain an electric field enhancing effect by propagation type surface plasmon resonance. The combination of localized surface plasmon resonance in two or three types of metal gaps and propagation type surface plasmon resonance in one type of metal lattice structure enables highly sensitive optical analysis utilizing an electric field enhancement effect.
In particular, when the metal film 3 is the metal film 3A of the aspect A, even in the non-film formation region G of the metal film 3, electric field enhancement can be generated by localized surface plasmon resonance, and optical using the electric field enhancement Analysis can be performed with higher sensitivity.
The analysis substrate 10 is also excellent in productivity. For example, as shown in the manufacturing method (I), metal can be deposited on the substrate 1B, and further, the metal nanoparticle dispersion can be coated and dried. In addition, it is not necessary to use a large amount of metal in order to form a structure capable of generating an electric field enhancement by localized surface plasmon resonance, and the raw material cost can be suppressed.
Since the above effect is exhibited, the analytical substrate 10 is useful for optical analysis utilizing electric field enhancement by surface plasmon resonance. As such an optical analysis method, the same as described above can be mentioned.
　上記効果を奏することから、分析用基板１０は、表面プラズモン共鳴による電場増強効果を利用した光学的分析に有用である。
　かかる光学的分析法としては、例えばラマン分光分析法、赤外分光法、蛍光分析等が挙げられる。これらの中でも、ラマン分光分析法が好適である。
　ラマン分光分析法とは、試料に光を照射したときに、入射光に対して分子の振動エネルギーだけシフトしたラマン散乱を観測し、分子レベルの構造を解析する分析手段である。得られたラマンスペクトルは、赤外分光法で得られる赤外スペクトルと同様に、分子の振動に基づく振動スペクトルであり、縦軸は散乱強度（Ｉｎｔｅｎｓｉｔｙ）、横軸はラマンシフト（ｃｍ－１）で表される。ラマン分光分析法と赤外分光分析法とでは同じ官能基の振動モードが同じ波数に検出されるが、赤外分光分析法と異なりラマン分光分析法は水系サンプルの測定が可能であるため、生体試料、食品試料等の分析などにおいて試料の前処理が必要ないなどの利点を有する。しかしながら、表面電場増強を行わない通常のラマン分光分析法は、ラマン散乱光の強度が非常に弱いのが欠点であった。
　表面増強ラマン分光分析法とは、ＳＥＲＳを利用したラマン分光分析法である。分析用基板１０にあっては、分析用基板１０表面に吸着した分子のラマン散乱（ストークス散乱およびアンチストークス散乱）強度をＳＥＲＳ効果によって著しく増強させることができるので、高感度分光分析が可能となる。実際には、希薄な微量検体においても、物質固有のスペクトルを検出することが可能となるため、環境測定、微量なバイオマーカーの測定、生物・化学兵器の検出等に有用である。 Since the above effect is exhibited, the analysis substrate 10 is useful for optical analysis utilizing an electric field enhancement effect by surface plasmon resonance.
Examples of such optical analysis include Raman spectroscopy, infrared spectroscopy, and fluorescence analysis. Among these, Raman spectroscopy is preferable.
The Raman spectroscopy is an analysis means for observing the Raman scattering shifted by the vibrational energy of the molecule with respect to the incident light when the sample is irradiated with light, and analyzing the structure at the molecular level. Similar to the infrared spectrum obtained by infrared spectroscopy, the obtained Raman spectrum is a vibration spectrum based on the vibration of the molecule, the vertical axis is the scattering intensity (Intensity), and the horizontal axis is the Raman shift (cm −1 ) Is represented by The vibration mode of the same functional group is detected in the same wave number in the Raman spectroscopy and the infrared spectroscopy, but unlike the infrared spectroscopy, the Raman spectroscopy can measure the aqueous sample, so the living body It has the advantage of not requiring pretreatment of the sample in analysis of the sample, food sample, etc. However, conventional Raman spectroscopy without surface electric field enhancement has the disadvantage that the intensity of the Raman scattered light is very low.
Surface enhanced Raman spectroscopy is Raman spectroscopy using SERS. In the analysis substrate 10, the Raman scattering (Stokes scattering and anti-Stokes scattering) intensity of the molecules adsorbed on the surface of the analysis substrate 10 can be significantly enhanced by the SERS effect, which enables high sensitivity spectral analysis. . In fact, even in the case of a dilute trace sample, it is possible to detect a spectrum unique to a substance, which is useful for environmental measurement, measurement of a trace biomarker, detection of a biological or chemical weapon, and the like.
　以上、実施形態を示して本発明を説明したが、本発明はこれらの実施形態に限定されるものではない。上記実施形態における各構成およびそれらの組み合わせ等は一例であり、本発明の趣旨を逸脱しない範囲内で、構成の付加、省略、置換、およびその他の変更が可能である。 Although the present invention has been described with the embodiments shown above, the present invention is not limited to these embodiments. The configurations and combinations thereof in the above embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible without departing from the spirit of the present invention.
　例えば、図４には、非成膜領域Ｇの上面視での形状が帯状である例を示したが、非成膜領域Ｇの上面視での形状はこれに限定されるものではなく、他の形状、例えば円形状、矩形状、樹形状、不定形状等であってもよい。
　複数の非成膜領域Ｇそれぞれの形状や大きさや分布がランダムである（一定ではない）例を示したが、複数の非成膜領域Ｇそれぞれの形状や大きさが一定であってもよい。複数の非成膜領域Ｇが規則的に配列していてもよい。
　図５には、非成膜領域Ｇを囲む金属表面３ａが傾斜面である例を示したが、金属表面３ａは非傾斜面であってもよい。また、金属表面３ａは平滑面であっても凹凸面であってもよい。
　金属膜が、基板の第一面上に金属を堆積させる方法（スパッタリング法や真空蒸着法等）により形成された金属膜である場合、非成膜領域Ｇを囲む金属表面は、局所的に傾斜面であり、また凹凸面であることが多い。 For example, FIG. 4 shows an example in which the shape of the non-film formation region G in a top view is a band shape, but the shape of the non-film formation region G in a top view is not limited thereto. For example, it may have a circular shape, a rectangular shape, a tree shape, or an irregular shape.
Although the shape, size, and distribution of each of the plurality of non-film formation regions G are random (not constant), the shape and size of each of the plurality of non-film formation regions G may be constant. The plurality of non-film formation regions G may be regularly arranged.
Although FIG. 5 shows an example in which the metal surface 3 a surrounding the non-film formation region G is an inclined surface, the metal surface 3 a may be a non-inclined surface. The metal surface 3a may be a smooth surface or an uneven surface.
When the metal film is a metal film formed by a method of depositing metal on the first surface of the substrate (sputtering method, vacuum evaporation method, etc.), the metal surface surrounding the non-film formation region G is locally inclined In many cases, it is an irregular surface.
　以下に実施例を用いて本発明をさらに詳しく説明するが、本発明はこれら実施例に限定されるものではない。
　各例で用いた測定方法を以下に示す。なお、周期的凹凸構造の凸部の高さ及びピッチの測定方法は前記の通りである。 EXAMPLES The present invention will be described in more detail using the following examples, but the present invention is not limited to these examples.
The measuring method used in each case is shown below. In addition, the measuring method of the height and pitch of the convex part of a periodic uneven structure is as above-mentioned.
（金属膜表面の２５℃におけるシート抵抗）
　一般的な導通試験に用いる抵抗率計（ロレスタＡＸ　ＭＣＰ－Ｔ３７０）にて２５℃でシート抵抗測定を行った。金属構造体を構成する金属膜は非常に薄いので、抵抗率計のプローブは薄膜測定用のＰＳＰオプションプローブ （ＭＣＰ－ＴＰ０６Ｐ）ピン間１．５ｍｍを使用して、ｎ＝５以上の平均値により測定値（Ω／□）を取得した。 (Sheet resistance of metal film surface at 25 ° C)
The sheet resistance was measured at 25 ° C. with a resistivity meter (Loresta AX MCP-T370) used in a general continuity test. Since the metal film that composes the metal structure is very thin, the probe of the resistivity meter uses 1.5 mm between the pins of the PSP option probe (MCP-TP06P) pin for thin film measurement, with an average value of n = 5 or more The measured value (Ω / □) was obtained.
（非成膜領域Ｇを介して対向する金属表面間の距離）
　金属膜３は、金属膜と金属膜中に散在する非成膜領域Ｇから構成される海島構造（海島構造の海（金属＝成膜領域）に対する島（非成膜領域Ｇにおける間隙）よりなる）を構成しており、金属表面３ａ間の距離は以下の測定方法によって測定した。
　すなわち、金属膜３の表面において互いに１００μｍ以上離れた５箇所から倍率２０万倍で０．６μｍ×０．４５μｍの領域のＳＥＭ像を取得し、それぞれのＳＥＭ像において非成膜領域Ｇ部分の測長を行う。この倍率におけるＳＥＭ像では輪郭が不鮮明になる場合があるため、ＳＥＭ像取得後にＡｄｏｂｅ　Ｐｈｏｔｏｓｈｏｐまたは同等の機能を有する画像処理ソフトウェアを使用して、画像のコントラストを強調するか、或いは画像の濃淡を２値化して測長を容易にする。ここで、非成膜領域Ｇ部分の短軸方向の間隙をナノギャップと呼ぶ。ナノギャップにおける間隙の測長は、先ず上記のようにして得たＳＥＭ像に対角線ＬＤを２本引き、対角線が交差する全ての非成膜領域Ｇ部分に関して短軸方向のギャップ幅を測長する。測長は上記対角線が各非成膜領域Ｇと交差する交差点において行うが、具体的には、上記対角線がある非成膜領域Ｇと成す交差距離の１／２の点Ｐを定義し、かつ上記点Ｐを通りつつ最も短い距離で非成膜領域Ｇを２分割する直線ＬＧを引き、最後に直線ＬＧが非成膜領域Ｇを通過する距離ＩＧを測長する。ＩＧの測長を上記５箇所のＳＥＭ像について行い、全ての測定値の平均値を求めたものを非成膜領域Ｇのナノギャップの平均値ＩＧＡＶＥとする。この平均値ＩＧＡＶＥを金属表面３ａ間の距離とする。 (Distance between opposing metal surfaces through non-film formation area G)
The metal film 3 is formed of an island (a gap in the non-film formation region G) with respect to a sea-island structure (sea-island structure sea (metal = film formation region)) composed of the metal film and the non-film formation region G dispersed in the metal film. And the distance between the metal surfaces 3a was measured by the following measurement method.
That is, SEM images of an area of 0.6 μm × 0.45 μm are obtained at a magnification of 200,000 and five points separated by 100 μm or more from each other on the surface of the metal film 3 and measurement of the non-film formation area G in each SEM image Do the length. Since the SEM image at this magnification may blur the outline, use Adobe Photoshop or similar image processing software after the SEM image acquisition to enhance the contrast of the image or Make it easy to measure by digitizing. Here, the gap in the minor axis direction of the non-film formation region G is called a nanogap. Measurement gaps in the nanogap, first two arguments diagonal L D in the SEM image obtained as described above, all the non-deposition region G moiety regard measuring the gap width in the minor axis direction of the diagonal lines Do. The length measurement is performed at the intersection where the diagonal intersects each non-film formation region G. Specifically, a point P which is a half of the intersection distance formed by the diagonal with the non-film formation region G is defined. drawing a straight line L G that 2 divides the non-deposition region G in the shortest distance, while as the point P, and measuring the distance I G of the last straight line L G passes through the non-deposition region G. The measurement of I G performs the SEM images of 5 places above, the average value I GAVE nanogap all non film formation region G ones determined an average value of the measured values. This average value I GAVE is taken as the distance between the metal surfaces 3a.
（金属膜の厚さ（成膜領域の平均厚さ））
　金属膜３の厚さ（成膜領域の平均厚さ）は、前述の方法により測定した。すなわち、基板上に成膜してある金属膜３に対して、鋭利なナイフの先で非常に細い傷（スクラッチ）をつけ、その傷を含む領域を触針式段差計（微細形状測定機ＥＴ４０００Ａ、小坂研究所）にて測定し、傷の底面（基板が露出している箇所）と金属膜３の表面との平均的な高低差を求める方法により、金属膜３の平均厚さを測定した。
　なお、実施例では触針式段差系を使用したが、原子間力顕微鏡（ＡＦＭ）像を取得して同様に基板が露出している部分と金属膜３の表面との平均的な高低差を求めても同様の結果を得ることができる。 (Thickness of metal film (average thickness of film formation area))
The thickness of the metal film 3 (average thickness of the film formation region) was measured by the above-mentioned method. That is, a very thin scratch (scratch) is made with a sharp knife tip to the metal film 3 deposited on the substrate, and the area including the scratch is measured by a stylus-type step meter (fine shape measuring machine ET4000A The average thickness of the metal film 3 was measured by a method of measuring the average height difference between the bottom surface of the flaw (where the substrate is exposed) and the surface of the metal film 3 by the Kosaka Research Institute, Ltd. .
In the embodiment, a stylus type step system is used, but an atomic force microscope (AFM) image is obtained to similarly average the difference in height between the exposed portion of the substrate and the surface of the metal film 3 The same result can be obtained even if it is determined.
（金属ナノ粒子の平均一次粒子径）
　金属ナノ粒子の平均一次粒子径は、前述の方法により測定した。すなわち、ＳＥＭを用い、倍率２０万倍にて分析用基板の表面を観察して金属ナノ粒子の一次粒子径を測長し、ｎ＝２０の平均値を算出し、その値を平均一次粒子径とした。 (Average primary particle size of metal nanoparticles)
The average primary particle size of the metal nanoparticles was measured by the method described above. That is, the surface of the substrate for analysis is observed at a magnification of 200,000 using SEM, the primary particle diameter of the metal nanoparticles is measured, the average value of n = 20 is calculated, and the value is the average primary particle diameter. And
（隣り合う２つの金属ナノ粒子間の最短距離）
　隣り合う２つの金属ナノ粒子間の最短距離は、前述の方法により測定した。すなわち、ＳＥＭを用い、倍率２０万倍にて分析用基板の表面を観察し、像中で隣り合う２つの金属ナノ粒子の間隙を実測し、ｎ＝２０の平均値を算出し、その値を前記最短距離とした。 (The shortest distance between two adjacent metal nanoparticles)
The shortest distance between two adjacent metal nanoparticles was measured by the method described above. That is, the surface of the substrate for analysis is observed at a magnification of 200,000 using SEM, the gap between two metal nanoparticles adjacent in the image is measured, and an average value of n = 20 is calculated. The shortest distance was taken.
（ラマン散乱強度の測定）
　分析用基板の表面（金属膜、金属ナノ粒子等を設けた面）に濃度１００μＭの４、４’－ビピリジル水溶液５μＬを滴下し、ラマン分光光度計（Ａｌｍｅｇａ　ＸＲ、サーモフィッシャーサイエンティフィック社）を用いてそれぞれラマンスペクトルの測定を行った。励起波長７８０ｎｍ、出力１０ｍＷのレーザーを光源とし、検出ピーク１６０７ｃｍ－１の強度（Ｉｎｔｅｎｓｉｔｙ）で各測定値を比較した。ラマン条件は、レーザー出力を１００％、アパーチャを径１００μｍのピンホール、露光回数を６４回とした。 (Measurement of Raman scattering intensity)
Add 5 μL of 100 μM 4, 4'-bipyridyl aqueous solution to the surface of the analysis substrate (surface provided with metal film, metal nanoparticles etc.), and use a Raman spectrophotometer (Almega XR, Thermo Fisher Scientific Co., Ltd.) The Raman spectrum was measured using each. A laser with an excitation wavelength of 780 nm and an output of 10 mW was used as a light source, and each measured value was compared at an intensity (Intensity) of a detection peak of 1607 cm −1 . The Raman conditions were 100% laser output, a pinhole with a diameter of 100 μm, and 64 exposures.
（実施例１）
　図１に示した分析用基板１０と同様の構成であって金属膜３が態様Ａの金属膜３Ａである分析用基板を以下の手順で製造した。
　平均粒子径６００ｎｍのコロイダルシリカ粒子を石英基板上に以下に述べるＬＢ法によって単層コーティングした。先ず、疎水化剤としてＮ－フェニル－３－アミノプロピルトリメトキシシランをシリカ粒子スラリーに添加し、反応温度４０℃にて疎水化を行った。その後、エタノール：クロロホルム＝３０：７０の混合溶媒を使用して、疎水化したシリカ粒子を油層抽出した。次に２１℃、ｐＨ７．２の下層水の水面に、上記疎水化粒子スラリーを滴下して行き、水面上に粒子単層膜を形成した。さらにバリアにて粒子単層膜を圧縮しながら、水中に予め浸漬しておいた清浄で平坦な石英基板を５ｍｍ／ｍｉｎにて徐々に引き上げ、水面の粒子単層膜を石英基板上に移し取った。その後、ドライエッチング装置（東京エレクトロン社製ＭＥ５１０Ｉ）を使用して、１．２Ｐａ、２０００／１８００Ｗ、Ｃｌ２＝８０ｓｃｃｍ、１００ｓｅｃの条件でドライエッチングを行い、構造周期（ピッチ）６００ｎｍ、構造高さ（３つの粒子の中心点から構造頂部までの垂直距離）５２ｎｍの周期的凹凸構造を得た。さらにスパッタリング装置（イオンスパッタ装置Ｅ－１０３０、日立ハイテクノロジーズ）を使用し、この周期的凹凸構造上にＡｕ薄膜を圧力６～８Ｐａ、電流値１５ｍＡ、成膜速度１１．６ｎｍ／ｍｉｎにて５．８ｎｍ厚さまで成膜した。最後に、Ａｕ薄膜上にＡｕナノ粒子分散液（平均一次粒子径２０．７ｎｍ）をスプレー塗布し乾燥させる工程を３回繰り返すことで、Ａｕナノ粒子を基板上に分散配置した。
　図６に、得られた分析用基板のＳＥＭ像を示す。 Example 1
A substrate for analysis having the same configuration as the substrate for analysis 10 shown in FIG. 1 and in which the metal film 3 is the metal film 3A of the embodiment A was manufactured in the following procedure.
Colloidal silica particles having an average particle diameter of 600 nm were single-layer coated on a quartz substrate by the LB method described below. First, N-phenyl-3-aminopropyltrimethoxysilane as a hydrophobizing agent was added to the silica particle slurry, and hydrophobization was performed at a reaction temperature of 40.degree. Thereafter, the hydrophobized silica particles were subjected to oil layer extraction using a mixed solvent of ethanol: chloroform = 30: 70. Next, the above-mentioned hydrophobized particle slurry was dropped onto the water surface of the lower layer water of pH 7.2 at 21 ° C. to form a particle monolayer film on the water surface. Furthermore, while compressing the particle monolayer film with the barrier, the clean flat quartz substrate previously immersed in water is gradually pulled up at 5 mm / min, and the particle monolayer film on the water surface is transferred onto the quartz substrate The After that, dry etching is performed under the conditions of 1.2 Pa, 2000/1800 W, Cl 2 = 80 sccm, 100 sec using a dry etching apparatus (ME510I manufactured by Tokyo Electron Ltd.), and the structure period (pitch) 600 nm, structure height ( Vertical distance from the center point of the three particles to the top of the structure) 52 nm periodic relief structure was obtained. Furthermore, using a sputtering apparatus (ion sputtering apparatus E-1030, Hitachi High-Technologies), the Au thin film was pressured on the periodic uneven structure at a pressure of 6 to 8 Pa, a current value of 15 mA, and a deposition rate of 11.6 nm / min. The film was formed to a thickness of 8 nm. Finally, the step of spray coating an Au nanoparticle dispersion (average primary particle diameter: 20.7 nm) on an Au thin film and drying was repeated three times to disperse and arrange Au nanoparticles on the substrate.
FIG. 6 shows an SEM image of the obtained analysis substrate.
（実施例２）
　図１に示した分析用基板１０と同様の構成であって金属膜３が態様Ｂの金属膜３Ｂである分析用基板を以下の手順で製造した。
　平均粒子径６００ｎｍのコロイダルシリカ粒子を石英基板上に以下に述べるＬＢ法によって単層コーティングした。先ず、疎水化剤としてＮ－フェニル－３－アミノプロピルトリメトキシシランをシリカ粒子スラリーに添加し、反応温度４０℃にて疎水化を行った。その後、エタノール：クロロホルム＝３０：７０の混合溶媒を使用して、疎水化したシリカ粒子を油層抽出した。次に２１℃、ｐＨ７．２の下層水の水面に、上記疎水化粒子スラリーを滴下して行き、水面上に粒子単層膜を形成した。さらにバリアにて粒子単層膜を圧縮しながら、水中に予め浸漬しておいた清浄で平坦な石英基板を５ｍｍ／ｍｉｎにて徐々に引き上げ、水面の粒子単層膜を石英基板上に移し取った。その後、ドライエッチング装置（東京エレクトロン社製ＭＥ５１０Ｉ）を使用して、１．２Ｐａ、２０００／１８００Ｗ、Ｃｌ２＝８０ｓｃｃｍ、１００ｓｅｃの条件でドライエッチングを行い、構造周期（ピッチ）６００ｎｍ、構造高さ（３つの粒子の中心点から構造頂部までの垂直距離）５２ｎｍの周期的凹凸構造を得た。さらにスパッタリング装置（イオンスパッタ装置Ｅ－１０３０、日立ハイテクノロジーズ）を使用し、この周期的凹凸構造上にＡｕ薄膜を圧力６～８Ｐａ、電流値１５ｍＡ、成膜速度１１．６ｎｍ／ｍｉｎにて８１．０ｎｍ厚さまで成膜した。最後に、Ａｕ薄膜上にＡｕナノ粒子分散液（平均一次粒子径２０．７ｎｍ）をスプレー塗布し乾燥させる工程を３回繰り返すことで、Ａｕナノ粒子を基板上に分散配置した。
　図７に、得られた分析用基板のＳＥＭ像を示す。 (Example 2)
A substrate for analysis having the same configuration as the substrate for analysis 10 shown in FIG. 1 and in which the metal film 3 is the metal film 3B of the embodiment B was manufactured in the following procedure.
Colloidal silica particles having an average particle diameter of 600 nm were single-layer coated on a quartz substrate by the LB method described below. First, N-phenyl-3-aminopropyltrimethoxysilane as a hydrophobizing agent was added to the silica particle slurry, and hydrophobization was performed at a reaction temperature of 40.degree. Thereafter, the hydrophobized silica particles were subjected to oil layer extraction using a mixed solvent of ethanol: chloroform = 30: 70. Next, the above-mentioned hydrophobized particle slurry was dropped onto the water surface of the lower layer water of pH 7.2 at 21 ° C. to form a particle monolayer film on the water surface. Furthermore, while compressing the particle monolayer film with the barrier, the clean flat quartz substrate previously immersed in water is gradually pulled up at 5 mm / min, and the particle monolayer film on the water surface is transferred onto the quartz substrate The After that, dry etching is performed under the conditions of 1.2 Pa, 2000/1800 W, Cl 2 = 80 sccm, 100 sec using a dry etching apparatus (ME510I manufactured by Tokyo Electron Ltd.), and the structure period (pitch) 600 nm, structure height ( Vertical distance from the center point of the three particles to the top of the structure) 52 nm periodic relief structure was obtained. Furthermore, using a sputtering apparatus (ion sputtering apparatus E-1030, Hitachi High-Technologies Corporation), an Au thin film was pressured on the periodic uneven structure at a pressure of 6 to 8 Pa, a current value of 15 mA, and a deposition rate of 11.6 nm / min. The film was formed to a thickness of 0 nm. Finally, the step of spray coating an Au nanoparticle dispersion (average primary particle diameter: 20.7 nm) on an Au thin film and drying was repeated three times to disperse and arrange Au nanoparticles on the substrate.
FIG. 7 shows an SEM image of the obtained analysis substrate.
（比較例１）
　金属膜も金属粒子も付与せず、何も表面に付着していない清浄な表面を有する、平坦な石英基板を準備した。 (Comparative example 1)
A flat quartz substrate was prepared with a clean surface with no metal film or metal particles applied and nothing attached to the surface.
（比較例２）
　金属膜も金属粒子も付与せず、何も表面に付着していない清浄な表面を有する、平坦な石英基板を準備した。その後、基板上にＡｕナノ粒子分散液（平均一次粒子径２０．７ｎｍ）をスプレー塗布し乾燥させる工程を３回繰り返すことで、実施例１～２と同様の散布密度にてＡｕナノ粒子を基板上に分散配置した。 (Comparative example 2)
A flat quartz substrate was prepared with a clean surface with no metal film or metal particles applied and nothing attached to the surface. Thereafter, the step of spray-coating the Au nanoparticle dispersion (average primary particle diameter 20.7 nm) on the substrate and drying the same is repeated three times to obtain the Au nanoparticles at the same dispersion density as in Examples 1 and 2 Distributed on the top.
（比較例３）
　平均粒子径６００ｎｍのコロイダルシリカ粒子を石英基板上に以下に述べるＬＢ法によって単層コーティングした。先ず、疎水化剤としてＮ－フェニル－３－アミノプロピルトリメトキシシランをシリカ粒子スラリーに添加し、反応温度４０℃にて疎水化を行った。その後、エタノール：クロロホルム＝３０：７０の混合溶媒を使用して、疎水化したシリカ粒子を油層抽出した。次に２１℃、ｐＨ７．２の下層水の水面に、上記疎水化粒子スラリーを滴下して行き、水面上に粒子単層膜を形成した。さらにバリアにて粒子単層膜を圧縮しながら、水中に予め浸漬しておいた清浄で平坦な石英基板を５ｍｍ／ｍｉｎにて徐々に引き上げ、水面の粒子単層膜を石英基板上に移し取った。その後、ドライエッチング装置（東京エレクトロン社製ＭＥ５１０Ｉ）を使用して、１．２Ｐａ、２０００／１８００Ｗ、Ｃｌ２＝８０ｓｃｃｍ、１００ｓｅｃの条件でドライエッチングを行い、構造周期（ピッチ）６００ｎｍ、構造高さ（３つの粒子の中心点から構造頂部までの垂直距離）５２ｎｍの周期的凹凸構造を得た。さらにスパッタリング装置（イオンスパッタ装置Ｅ－１０３０、日立ハイテクノロジーズ）を使用し、この周期的凹凸構造上にＡｕ薄膜を圧力６～８Ｐａ、電流値１５ｍＡ、成膜速度１１．６ｎｍ／ｍｉｎにて４４．２ｎｍ厚さまで成膜した。 (Comparative example 3)
Colloidal silica particles having an average particle diameter of 600 nm were single-layer coated on a quartz substrate by the LB method described below. First, N-phenyl-3-aminopropyltrimethoxysilane as a hydrophobizing agent was added to the silica particle slurry, and hydrophobization was performed at a reaction temperature of 40.degree. Thereafter, the hydrophobized silica particles were subjected to oil layer extraction using a mixed solvent of ethanol: chloroform = 30: 70. Next, the above-mentioned hydrophobized particle slurry was dropped onto the water surface of the lower layer water of pH 7.2 at 21 ° C. to form a particle monolayer film on the water surface. Furthermore, while compressing the particle monolayer film with the barrier, the clean flat quartz substrate previously immersed in water is gradually pulled up at 5 mm / min, and the particle monolayer film on the water surface is transferred onto the quartz substrate The After that, dry etching is performed under the conditions of 1.2 Pa, 2000/1800 W, Cl 2 = 80 sccm, 100 sec using a dry etching apparatus (ME510I manufactured by Tokyo Electron Ltd.), and the structure period (pitch) 600 nm, structure height ( Vertical distance from the center point of the three particles to the top of the structure) 52 nm periodic relief structure was obtained. Furthermore, using a sputtering apparatus (ion sputtering apparatus E-1030, Hitachi High-Technologies), on the periodic uneven structure, an Au thin film is formed at a pressure of 6 to 8 Pa, a current value of 15 mA, and a deposition rate of 11.6 nm / min. The film was formed to a thickness of 2 nm.
　実施例１～２および比較例１～３の分析用基板を用い、ラマン散乱強度の測定を行った。結果を表１に示す。 The Raman scattering intensity was measured using the analysis substrates of Examples 1 to 2 and Comparative Examples 1 to 3. The results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000001
  
Figure JPOXMLDOC01-appb-T000001
  
　比較例１および比較例２の分析用基板では、ラマン散乱を検出できなかった。また、比較例３の分析用基板では、ラマン散乱を検出できたが、その強度はすべての実施例の強度より低い値となった。
　これに対し、実施例１～２の分析用基板では、試料濃度１００μＭにおけるラマン散乱が各々高強度で得られており、試料濃度１ｎＭという低濃度の試料でもラマン散乱を検出することができた。 The analysis substrates of Comparative Example 1 and Comparative Example 2 could not detect Raman scattering. In addition, although the Raman scattering could be detected in the substrate for analysis of Comparative Example 3, its intensity was lower than the intensities of all the examples.
On the other hand, in the analysis substrates of Examples 1 and 2, Raman scattering at a sample concentration of 100 μM was obtained at high intensity, and Raman scattering could be detected even at a sample concentration as low as 1 nM.
　１　基板
　１ａ　第一面
　３，３Ａ　金属膜
　５　金属ナノ粒子
　１０　分析用基板
　Ｇ　非成膜領域 1 substrate 1a first surface 3, 3A metal film 5 metal nanoparticle 10 substrate for analysis G non-deposited area

Claims (3)

  1. 　少なくとも第一面が誘電体または半導体からなり、前記第一面に、複数の凹部または凸部が周期的に二次元に配列した二次元格子構造を有する基板と、
    　前記基板の第一面上に設けられた、２５℃における表面のシート抵抗が５０００Ω／□以下である金属膜と、
    　前記金属膜上に分散配置された、平均一次粒子径が５～１００ｎｍである複数の金属ナノ粒子と、
    を備える、分析用基板。     A substrate having a two-dimensional lattice structure in which at least a first surface is made of a dielectric or a semiconductor, and a plurality of recesses or projections are periodically arranged in two dimensions on the first surface;
    A metal film provided on the first surface of the substrate and having a surface sheet resistance at 25 ° C. of 5000 Ω / □ or less;
    A plurality of metal nanoparticles dispersed on the metal film and having an average primary particle diameter of 5 to 100 nm;
    An analytical substrate comprising:
  2. 　前記二次元格子構造が、三角格子構造または正方格子構造である、請求項１に記載の分析用基板。 The analytical substrate according to claim 1, wherein the two-dimensional lattice structure is a triangular lattice structure or a square lattice structure.
  3. 　前記金属膜が、前記金属膜内に長軸方向の長さが１μｍ以下の島状の隙間形状として設けられた、金属が存在せず前記基板の第一面が露出している複数の非成膜領域を有する、請求項１または２に記載の分析用基板。 The metal film is provided as an island-like gap shape having a length of 1 μm or less in the major axis direction in the metal film, and a plurality of non-formed metal in which the first surface of the substrate is exposed without metal The analysis substrate according to claim 1, which has a membrane region.
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