JP6544504B2 - Analyzer and electronic equipment - Google Patents

Description

  The present invention relates to an analyzer and an electronic device.

  BACKGROUND ART In the fields of medicine, health, environment, food, public safety, etc., there is a demand for a sensing technology for detecting a trace amount of substance with high sensitivity, high accuracy, quickness and simplicity. Trace amounts of substances to be sensed are extremely diverse. For example, biological compounds such as bacteria, viruses, proteins, nucleic acids, various antigens and antibodies, and various compounds including inorganic molecules, organic molecules, and polymers It becomes an object of sensing. Conventionally, detection of trace substances has been performed through sampling, analysis and analysis, but since a dedicated device is required and the skill of the inspection worker is required, in-situ analysis has often been difficult. Therefore, it takes a long time (a few days or more) to obtain a test result. In the sensing technology, the demand for quickness and simplicity is very strong, and development of a sensor that can meet the demand is desired. For example, diagnosis of a patient who exhibits vomiting, diarrhea, fever at an airport etc. is urgently required to prevent the spread of infection. In addition, infection tests vary in whether they are bacteria or viruses, and it is important to rapidly identify the type of bacteria or virus to break the infection route.

  Due to such requirements, various types of sensors including electrochemical methods have been studied in recent years, but surface plasmon resonance (for reasons of possible integration, low cost, and arbitrary measurement environment) There is growing interest in sensors using SPR). For example, it is known to detect the presence or absence of adsorption of a substance, such as the presence or absence of adsorption of an antigen in an antigen-antibody reaction, using SPR generated on a metal thin film provided on the surface of a total reflection prism. In addition, methods of detecting the Raman scattering of a substance attached to a sensor site and using the surface-enhanced Raman scattering (SERS) to identify the attached substance are also studied.

As a structure of such a sensor, for example, Non-Patent Document 1 proposes a Disk-coupled dots-on-pillar antenna model (D2PA model) as a structure with an increased hotspot density (HSD). In the structure disclosed in Non-Patent Document 1, a method utilizing localized plasmons (LSP) generated in the gaps (nanogaps) between gold nanoparticles grown on the side surfaces of a pillar formed of SiO ₂ is proposed. It is adopted. The reference of Fig. As seen from 4, in the absence of nanoparticles, the enhancement of the electric field is | E ⁴ / E ₀ ⁴ | ̃10 ⁵ , ie, | E | ̃17.8 | E ₀ | If particles are present on the side of the pillar, then | E ⁴ / E ₀ ⁴ | ̃10 ⁷ , ie, | E | ̃56.2 | E ₀ |.

OPTICS EXPRESS, Vol. 19, No. 5, 2011, 3925-3936

However, in the structure disclosed in the above-mentioned Non-Patent Document 1, since the nanoparticles are formed by vapor deposition, it is difficult to control the nanogaps, and also in this document, the uniformity of SERS enhancement due to the variation is 22 It is reported that the value is as high as .4%. In addition, since the nano gap in the same document is as narrow as 5 nm or less, when the size of the sensing substance (the substance to be measured) is large, for example, 5 nm or more in diameter, the sensing substance enters the hot spot generated in the nano gap There is a problem that the SERS effect can not be sufficiently enhanced because it is impossible.

  One of the objects according to some aspects of the present invention is to provide an analysis device and an electronic device in which a hot spot is exposed on the surface of an electric field enhancing element and the plasmon enhancing effect is high.

  The present invention has been made to solve at least a part of the problems described above, and can be realized as the following aspects or application examples.

One aspect of the analyzer according to the present invention is a substrate, a first metal layer formed on the substrate, a dielectric column formed above the substrate, and the first dielectric layer formed on the dielectric column. And a second metal layer electrically insulated from one metal layer, wherein the second metal layer forms a plurality of metal rows arranged in a first direction at a first pitch P1; An electric field enhancing element, arranged side by side at a second pitch P2 in a second direction intersecting the first direction, and linearly polarized light in the first direction, linearly polarized light in the second direction, in the electric field enhancing element A light source for irradiating incident light of light or circularly polarized light, and a detector for detecting light emitted from the electric field enhancing element;
The arrangement of the second metal layer of the electric field enhancing element satisfies the relationship of the following formula (1),
P1 ≦ P2 ≦ Q + P2 / 10 (1)
[Here, Q represents the pitch of the diffraction grating given by the following formula (2).

(.Omega. / C). {. Epsilon..epsilon. (. Omega.) / (. Epsilon. +. Epsilon. (. Omega.)) ^1/2 = .epsilon.1 ^{/ 2} (.omega. / C) .sin .theta. + 2 m.pi./Q (m = 1,2,2,) ... (2)]
The distance G [nm] between the first metal layer and the second metal layer satisfies the relationship of the following formula (3).

20 [nm] <G. [epsilon] ¹ / 2.cos [theta] <270 [nm]. [Lambda] i / 785 [nm] (3)
[In the above formulas, ω is the angular frequency of the localized plasmon excited in the row of the second metal layer, ε (ω) is the dielectric constant of the metal constituting the first metal layer, ε is The dielectric constant around the first metal layer, c is the speed of light in vacuum, θ is the irradiation angle of the incident light, and the inclination angle from the thickness direction of the first metal layer, λi is the front Represents the wavelength [nm] of the incident light. ]
According to such an analysis device, the end portions of the upper surface and the lower surface of the second metal layer are each provided with an electric field enhancing element having a structure capable of contacting the substance to be analyzed, and the electric field enhancing element The hot spots formed by are exposed on the device surface. Therefore, the substance to be analyzed is likely to be located at the hot spot. Furthermore, since the first metal layer is disposed in the vicinity of the second metal layer, the resonance effect of the localized plasmon and the propagating plasmon can be generated. Therefore, the degree of enhancement of light based on plasmons is very large, and substances to be analyzed can be analyzed with extremely high sensitivity.

One aspect of the analyzer according to the present invention is a substrate, a first metal layer formed on the substrate, a dielectric column formed above the substrate, and the first dielectric layer formed on the dielectric column. And a second metal layer electrically insulated from one metal layer, wherein the second metal layer forms a plurality of metal rows arranged in a first direction at a first pitch P1; An electric field enhancing element, arranged side by side at a second pitch P2 in a second direction intersecting the first direction, and linearly polarized light in the first direction, linearly polarized light in the second direction, in the electric field enhancing element A light source for irradiating incident light of light or circularly polarized light, and a detector for detecting light emitted from the electric field enhancing element;
The arrangement of the second metal layer of the electric field enhancing element satisfies the relationship of the following formula (1),
P1 ≦ P2 ≦ Q + P2 / 10 (1)
[Here, Q represents the pitch of the diffraction grating given by the following formula (2).

(.Omega. / C). {. Epsilon..epsilon. (. Omega.) / (. Epsilon. +. Epsilon. (. Omega.)) ^1/2 = .epsilon.1 ^{/ 2} (.omega. / C) .sin .theta. + 2 m.pi./Q (m = 1,2,2,) ... (2)]
The analyzer which satisfy | fills the relationship of following formula (4), when the refractive index of the said board | substrate is set to n.

0.9 · ε ^1/2 ≦ n ≦ 1.1 · ε ^1/2 (4)
[In the above formulas, ω is the angular frequency of the localized plasmon excited in the row of the second metal layer, ε (ω) is the dielectric constant of the metal constituting the first metal layer, ε is The dielectric constant around the first metal layer, c is the speed of light in vacuum, θ is the irradiation angle of the incident light, and the inclination angle from the thickness direction of the first metal layer, n is the above Represents the refractive index of the substrate. ]
According to such an analysis device, the end portions of the upper surface and the lower surface of the second metal layer are each provided with an electric field enhancing element having a structure capable of contacting the substance to be analyzed, and the electric field enhancing element The hot spots formed by are exposed on the device surface. Therefore, the substance to be analyzed is likely to be located at the hot spot. Furthermore, since the first metal layer is disposed in the vicinity of the second metal layer, the resonance effect of the localized plasmon and the propagating plasmon can be generated. Therefore, the degree of enhancement of light based on plasmons is very large, and substances to be analyzed can be analyzed with extremely high sensitivity.

One aspect of the analyzer according to the present invention is a substrate, a first metal layer formed on the substrate, a dielectric column formed above the substrate, and the first dielectric layer formed on the dielectric column. And a second metal layer electrically insulated from one metal layer, wherein the second metal layer forms a plurality of metal rows arranged in a first direction at a first pitch P1; An electric field enhancing element, arranged side by side at a second pitch P2 in a second direction intersecting the first direction, and a light source for irradiating the electric field enhancing element with incident light of linearly polarized light in the first direction A detector for detecting light emitted from the electric field enhancing element;
The arrangement of the second metal layer of the electric field enhancing element satisfies the relationship of the following formula (5),
P1 <P2 ≦ Q + P1 (5)
[Here, Q represents the pitch of the diffraction grating given by the following formula (2).

(.Omega. / C). {. Epsilon..epsilon. (. Omega.) / (. Epsilon. +. Epsilon. (. Omega.)) ^1/2 = .epsilon.1 ^{/ 2} (.omega. / C) .sin .theta. + 2 m.pi./Q (m = 1,2,2,) ... (2)]
The analyzer whose distance G [nm] between the said 1st metal layer and the said 2nd metal layer satisfy | fills the relationship of following formula (3).

20 [nm] <G. [epsilon] ¹ / 2.cos [theta] <270 [nm]. [Lambda] i / 785 [nm] (3)
[In the above formulas, ω is the angular frequency of the localized plasmon excited in the row of the second metal layer, ε (ω) is the dielectric constant of the metal constituting the first metal layer, ε is The dielectric constant around the first metal layer, c is the speed of light in vacuum, θ is the irradiation angle of the incident light, and the inclination angle from the thickness direction of the first metal layer, λi is the front Represents the wavelength [nm] of the incident light. ]
According to such an analysis device, the end portions of the upper surface and the lower surface of the second metal layer are each provided with an electric field enhancing element having a structure capable of contacting the substance to be analyzed, and the electric field enhancing element Hot spots formed on the surface of the device are exposed on the device surface. Therefore, the substance to be analyzed is likely to be located at the hot spot. Furthermore, since the first metal layer is disposed in the vicinity of the second metal layer, the resonance effect of the localized plasmon and the propagating plasmon can be generated. Therefore, the degree of enhancement of light based on plasmons is very large, and substances to be analyzed can be analyzed with extremely high sensitivity.

One aspect of the analyzer according to the present invention is a substrate, a first metal layer formed on the substrate, a dielectric column formed above the substrate, and the first dielectric layer formed on the dielectric column. A second metal layer electrically isolated from the first metal layer, the second metal layer having a first pitch P1 in a first direction;
A plurality of metal lines are arranged side by side, and the metal lines are arranged side by side at a second pitch P2 in a second direction intersecting the first direction, the electric field enhancing element, the electric field enhancing element, A light source for irradiating incident light of linearly polarized light in a first direction, and a detector for detecting light emitted from the electric field enhancing element;
The arrangement of the second metal layer of the electric field enhancing element satisfies the relationship of the following formula (6),
P1 <P2 ≦ Q + P2 / 10 (6)
[Here, Q represents the pitch of the diffraction grating given by the following formula (2).

(.Omega. / C). {. Epsilon..epsilon. (. Omega.) / (. Epsilon. +. Epsilon. (. Omega.)) ^1/2 = .epsilon.1 ^{/ 2} (.omega. / C) .sin .theta. + 2 m.pi./Q (m = 1,2,2,) ... (2)]
The analyzer which satisfy | fills the relationship of following formula (4), when the refractive index of the said board | substrate is set to n.

0.9 · ε ^1/2 ≦ n ≦ 1.1 · ε ^1/2 (4)
[In the above formulas, ω is the angular frequency of the localized plasmon excited in the row of the second metal layer, ε (ω) is the dielectric constant of the metal constituting the first metal layer, ε is The dielectric constant around the first metal layer, c is the speed of light in vacuum, θ is the irradiation angle of the incident light, and the inclination angle from the thickness direction of the first metal layer, n is the above Represents the refractive index of the substrate. ]
According to such an analysis device, the end portions of the upper surface and the lower surface of the second metal layer are each provided with an electric field enhancing element having a structure capable of contacting the substance to be analyzed, and the electric field enhancing element Hot spots formed on the surface of the device are exposed on the device surface. Therefore, the substance to be analyzed is likely to be located at the hot spot. Furthermore, since the first metal layer is disposed in the vicinity of the second metal layer, the resonance effect of the localized plasmon and the propagating plasmon can be generated. Therefore, the degree of enhancement of light based on plasmons is very large, and substances to be analyzed can be analyzed with extremely high sensitivity.

One aspect of the analyzer according to the present invention is a substrate, a first metal layer formed on the substrate, a dielectric column formed above the substrate, and the first dielectric layer formed on the dielectric column. And a second metal layer electrically insulated from one metal layer, wherein the second metal layer forms a plurality of metal rows arranged in a first direction at a first pitch P1; An electric field enhancing element, arranged side by side at a second pitch P2 in a second direction intersecting the first direction, and a light source for irradiating the electric field enhancing element with incident light of linearly polarized light in the second direction A detector for detecting light emitted from the electric field enhancing element;
The arrangement of the second metal layer of the electric field enhancing element satisfies the relationship of the following formula (5),
P1 <P2 ≦ Q + P1 (5)
[Here, Q represents the pitch of the diffraction grating given by the following formula (2).

(.Omega. / C). {. Epsilon..epsilon. (. Omega.) / (. Epsilon. +. Epsilon. (. Omega.)) ^1/2 = .epsilon.1 ^{/ 2} (.omega. / C) .sin .theta. + 2 m.pi./Q (m = 1,2,2,) ... (2)]
The analyzer whose distance G [nm] between the said 1st metal layer and the said 2nd metal layer satisfy | fills the relationship of following formula (7).

20 [nm] <G. [epsilon] ¹ / 2.cos [theta] <= 220 [nm]. [Lambda] i / 785 [nm] (7)
[In the above formulas, ω is the angular frequency of the localized plasmon excited in the row of the second metal layer, ε (ω) is the dielectric constant of the metal constituting the first metal layer, ε is The dielectric constant around the first metal layer, c is the speed of light in vacuum, θ is the irradiation angle of the incident light, and the inclination angle from the thickness direction of the first metal layer, λi is the front Represents the wavelength [nm] of the incident light. ]
According to such an analysis device, the end portions of the upper surface and the lower surface of the second metal layer are each provided with an electric field enhancing element having a structure capable of contacting the substance to be analyzed, and the electric field enhancing element Hot spots formed on the surface of the device are exposed on the device surface. Therefore, the substance to be analyzed is likely to be located at the hot spot. Furthermore, since the first metal layer is disposed in the vicinity of the second metal layer, the resonance effect of the localized plasmon and the propagating plasmon can be generated. Therefore, the degree of enhancement of light based on plasmons is very large, and substances to be analyzed can be analyzed with extremely high sensitivity.

  In the analyzer according to the present invention, the detector may detect the Raman scattered light enhanced by the electric field enhancing element.

  According to such an analysis apparatus, since the electric field enhancing element having a large enhancement degree of light based on plasmons is provided, the Raman scattered light can be sufficiently enhanced, and the identification of a trace substance can be easily performed. .

  One aspect of an electronic device according to the present invention is an analysis device described above, a calculation unit that calculates health care information based on detection information from the detector, a storage unit that stores the health care information, and the health And a display unit for displaying medical information.

  According to such an electronic device, the electric field enhancing element having a large degree of light enhancement based on plasmons can be provided, a trace substance can be easily detected, and highly accurate health care information can be provided. .

  In the electronic device of the present invention, the health care information is selected from at least one biological substance selected from the group consisting of bacteria, viruses, proteins, nucleic acids, and antigens and antibodies, or inorganic molecules and organic molecules. Information regarding the presence or absence or amount of at least one compound may also be included.

  According to such an electronic device, useful health care information can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS The perspective view which shows the electric field enhancing element of embodiment typically. The schematic diagram which looked at the electric field enhancing element of the embodiment from the thickness direction of the first metal layer. The schematic diagram of the cross section perpendicular | vertical to the 1st direction of the electric field enhancement element of embodiment. The schematic diagram of a cross section perpendicular | vertical to the 2nd direction of the electric field enhancement element of embodiment. The schematic diagram which looked at the electric field enhancing element of the embodiment from the thickness direction of the first metal layer. The schematic diagram of a cross section perpendicular | vertical to the 1st direction of the electric field enhancement element of the modification of embodiment. The planar schematic diagram which shows an example of the metal row of an electric field enhancement element. The planar schematic diagram which shows an example of the metal row of an electric field enhancement element. Graph of dispersion relationship showing the incident light and dispersion curves of gold and silver. A graph showing the relationship between the dielectric constant of Ag and the wavelength. The graph which shows the dispersion relation of the dispersion curve of a metal, localized plasmon, and incident light. The schematic diagram which shows the principal part of the electric field enhancement element of embodiment compared with a GSPP model. The schematic diagram which shows the relationship between arrangement | sequence of a 2nd metal layer, and LSP and PSP. BRIEF DESCRIPTION OF THE DRAWINGS Schematic of the analyzer of embodiment. Schematic of the electronic device of embodiment. The schematic diagram which shows an example of the model which concerns on an experiment example. The graph which shows the reflectance of the model which concerns on an experiment example, and the wavelength characteristic of SQRT. The graph which shows the wavelength characteristic and generation | occurrence | production position of the enhancement electric field which concern on an experiment example. The graph which shows the peak wavelength of the reflectance of a X600Y600 model, and gap G dependence. The graph which shows the reflectance of X780Y780 model, and the gap G dependence of SQRT. The graph of the wavelength characteristic of SQRT when the substrate of X780Y780160D20T_AG_80G model is made into PMMA, and when it is made into air. The graph which shows the gap G dependence of SQRT of X780Y180 model of AG and AU, and X600Y180 model. The graph which shows the gap G dependence of the near-field characteristic of 1 line ⊥ model. The graph which shows the gap G dependence of the near-field characteristic of 1 line ⊥ model. The figure which shows the model which concerns on an experiment example typically. The graph which shows the wavelength characteristic of SQRT of penetration model and non penetration model. The graph which shows the wavelength characteristic of SQRT of penetration model and non penetration model. The graph which shows the wavelength characteristic of SQRT of penetration model and non penetration model. The graph which shows the normalized reflectance characteristic of the model concerning an example of an experiment. Graph of dispersion relation concerning an example of an experiment. The graph which shows the enhancement degree profile of the model which concerns on an experiment example. Graph of dispersion relation concerning an example of an experiment.

  Hereinafter, some embodiments of the present invention will be described. The embodiment described below is an example of the present invention. The present invention is not limited to the following embodiments at all, and includes various modifications implemented without departing from the scope of the present invention. Note that not all of the configurations described below are necessarily essential configurations of the present invention.

1. Electric field enhancing element FIG. 1 is a perspective view of an electric field enhancing element 100 according to the present embodiment. FIG. 2 is a schematic view in which the electric field enhancing element 100 of the present embodiment is viewed in plan (as viewed in the thickness direction of the first metal layer 10). FIG.3 and FIG.4 is a schematic diagram of the cross section of the electric field enhancement element 100 of this embodiment. FIG. 5 is a schematic view of another example of the electric field enhancing element 100 of the present embodiment as viewed from the thickness direction of the first metal layer 10. FIG. 5 is a schematic view of the electric field enhancing element of the embodiment as viewed from the thickness direction of the first metal layer. FIG. 6 is a schematic view of a cross section perpendicular to the first direction of the electric field enhancing element of the modification of the embodiment. 7 and 8 are schematic plan views showing an example of the second metal row. The electric field enhancing element 100 of the present embodiment includes a first metal layer 10 and a second metal layer 30 disposed on a dielectric pillar 20 formed through the surface of the first metal layer 10. .

1.1. First Metal Layer The first metal layer 10 is not particularly limited as long as it provides a surface of a metal which does not transmit light or is semi-transparent, and can be, for example, a film, a layer or a film. The first metal layer 10 may be provided, for example, on the substrate 1. The substrate 1 in this case is not particularly limited, but a substrate that hardly affects the propagation type plasmon excited in the first metal layer 10 is preferable. Examples of the substrate 1 include a glass substrate, a silicon substrate, and a resin substrate. The shape of the surface of the substrate 1 on which the first metal layer 10 is provided is not particularly limited. When forming a regular structure on the surface of the first metal layer 10, it may have a surface corresponding to the regular structure, or when the surface of the first metal layer 10 is a plane, The surface may be flat. In the examples of FIGS. 1 to 5, the first metal layer 10 is provided on the surface (planar surface) of the substrate 1.

  By selecting the refractive index n of the substrate 1 to be a value close to the square root of the peripheral dielectric constant of the first metal layer 10 under specific conditions, a high degree of electric field enhancement can be obtained. Details of this will be described later.

  Also, although the expression plane is used, such expression does not indicate that the surface is a smooth (smooth) mathematically exact plane without slight unevenness. For example, there may be unevenness on the surface due to atoms making up or unevenness due to secondary structures (crystals, grain agglomerates, grain boundaries, etc.) of the material to be formed, microscopically It may not be a strict plane if it sees. However, even in such a case, when viewed from a more macroscopic viewpoint, these asperities become inconspicuous, and the surface can be observed to such an extent that it can be referred to as a plane. Therefore, in the present specification, if it can be recognized as a plane when viewed from such a macroscopic viewpoint, this is referred to as a plane.

  Further, in the present embodiment, the thickness direction of the first metal layer 10 may coincide with the thickness direction of the second metal layer 30 described later. In the present specification, the thickness direction of the first metal layer 10 may be referred to as a thickness direction, a height direction, or the like in the case of describing the dielectric pillar 20 and the second metal layer 30 described later. Further, for example, when the first metal layer 10 is provided on the surface of the substrate 1, the normal direction of the surface of the substrate 1 may be referred to as a thickness direction, a thickness direction, or a height direction. Furthermore, viewed from the substrate 1, the direction on the first metal layer 10 side may be expressed as upper or upper, and the opposite direction may be expressed as lower or lower.

  The first metal layer 10 may or may not be penetrated by a dielectric post 20 described later. As a mode which is not penetrated, when the dielectric pillar 20 is placed on the first metal layer 10 and when the first metal layer 10 is thick, the dielectric pillar 20 is formed on the surface side of the first metal layer 10. And the case where the lower part of the is embedded.

  The first metal layer 10 can be formed by, for example, a method such as vapor deposition, sputtering, casting, or machining. In addition, the first metal layer 10 may be formed in the same step as the second metal layer 30 described later. When the first metal layer 10 is provided on the substrate 1 in the form of a thin film, the first metal layer 10 may be provided on the entire plane of the substrate 1 excluding the dielectric pillar 20 or on a part of the substrate 1. The thickness of the first metal layer 10 is not particularly limited as long as propagation plasmons can be excited in the first metal layer 10, and for example, 10 nm or more and 1 mm or less, preferably 20 nm or more and 100 μm or less, more preferably 30 nm or more and 1 μm or less can do.

  The first metal layer 10 is a metal that can have an electric field oscillating in an opposite phase with an electric field applied by incident light and a polarization induced by the electric field, that is, when a specific electric field is applied, Constructed by a metal whose real part of the dielectric function has a negative value (has a negative dielectric constant) and the dielectric constant of the imaginary part has a dielectric constant smaller than the absolute value of the dielectric constant of the real part Ru. Examples of metals that can have such a dielectric constant in the visible light range include silver, gold, aluminum, copper, platinum, and alloys thereof.

  The first metal layer 10 has a function of generating propagating plasmons in the electric field enhancing element 100 of the present embodiment. By causing light to be incident on the first metal layer 10 under the conditions to be described later, propagation type plasmons are generated in the vicinity of the surface (end face in the thickness direction) of the first metal layer 10. Further, in the present specification, a quantum of vibration in which the vibration of the charge near the surface of the first metal layer 10 and the electromagnetic wave are coupled may be referred to as surface plasmon polariton (SPP). The propagation type plasmons generated in the first metal layer 10 can interact (hybridize) with localized plasmons generated in the second metal layer 30 described below under certain conditions.

1.2. Dielectric Column The dielectric column 20 is provided above the substrate 1. In the present specification, the wording "upper" may be, for example, "to form another specific one (hereinafter referred to as" B ")" above "the specific one (hereinafter referred to as" A "), etc. When used, the term "upper" is used as it includes the case where B is formed directly on A and the case where B is formed on another via A.

  Moreover, the words "upper", "lower", etc. are not words intended for the vertical relation depending on the installation state of the electric field enhancing element, and the substrate is in the lower state regardless of the installation state of the electric field enhancing element. This is a term that is intended for the upper and lower relationship in the case of seeing (the field of view was taken so that the substrate is below). Therefore, for example, if it is seen that the direction of gravity action is downward, even if the electric field enhancing element is installed such that the substrate is upward and the dielectric column is downward, the dielectric is raised above the substrate. The meaning of the presence of the column is to choose the field of view so that the substrate is below (ie in this case the direction of gravity acting upwards) and literally the dielectric above the substrate It is understood that a pillar is located.

  The provision of the dielectric pillar 20 above the substrate 1 includes the case where the dielectric pillar 20 is provided in contact with the substrate 1 and the case where the dielectric pillar 20 is provided apart from the substrate 1. When the dielectric pillar 20 is provided in contact with the substrate 1, the dielectric pillar 20 is provided to penetrate the first metal layer 10. In this case, the dielectric post 20 may be provided integrally with the substrate 1 or may be provided separately. In addition, as an aspect in which the dielectric pillar 20 is provided above the substrate 1 with being separated from the substrate 1, the dielectric pillar 20 is provided on the first metal layer 10, that is, the dielectric pillar 20 is provided above the substrate 1. The aspect provided through 1 metal layer 10 is mentioned. In this case, the dielectric post 20 may be provided on the substrate 1 via another member other than the first metal layer 10 or other members besides the first metal layer 10 (see FIG. 6). .

  In the examples of FIGS. 1, 3 and 4, the dielectric pillar 20 is provided to penetrate the surface of the first metal layer 10 (in this specification, such a model may be referred to as a penetration model). Then, the second metal layer 30 is disposed on the dielectric post 20. Therefore, the first metal layer 10 and the second metal layer 30 are spatially separated. In the example of FIG. 6, the dielectric post 20 is provided on the first metal layer 10. Also in this example, the second metal layer 30 is disposed on the dielectric pillar 20 (in this specification, such a model may be referred to as a non-penetration model). Therefore, the first metal layer 10 and the second metal layer 30 are spatially separated.

  In the electric field enhancing element 100 of the present embodiment, even if the dielectric pillar 20 is disposed in contact with the substrate 1 or is disposed away from the substrate 1, the same function and function can be exhibited. Hereinafter, as in the examples of FIGS. 1, 3 and 4, the case where the dielectric pillar 20 is provided to penetrate the surface of the first metal layer 10 will be described.

  The shape of the dielectric post 20 is not particularly limited as long as it is a shape that protrudes from the upper surface of the first metal layer 10 and can be disposed on the dielectric post 20. Examples of the shape of the dielectric column 20 include a columnar shape, a frustum shape, an inverted frustum shape, and a bump shape. The shape (contour shape) of the cross section obtained by cutting the dielectric column 20 in a plane parallel to the surface of the substrate 1 can be a circle, an ellipse, a polygon or a combination thereof, and the shape and size of the cross section The (size: size) may vary depending on the position of the cross section from the surface of the substrate 1.

  The dielectric pillar 20 may be integrally formed with the substrate 1 when the first metal layer 10 is a thin film. In the example of FIGS. 1 to 4, the dielectric pillars 20 are formed integrally with the substrate 1. The material of the dielectric column 20 may be the same as or different from that of the substrate 1.

The dielectric post 20 may be formed, for example, when molding the substrate 1. In addition, the dielectric column 20 may be formed by, for example, a method combining a method of photolithography with vapor deposition, sputtering, CVD, various coatings, and the like, a microcontact printing method, a nanoimprinting method, and the like. In addition, after the first metal layer 10 is formed, the dielectric post 20 is formed so as to form a through or non-through hole in the first metal layer 10 by photolithography or the like, and to be embedded in the hole It is also good. The dielectric pillars 20 may be formed before forming the first metal layer 10. In the case where the dielectric pillar 20 is formed before the formation of the first metal layer 10, the first metal layer 10 and the second metal layer 30 may be able to be formed in one step. In some cases, the device 100 can be manufactured efficiently.

  In the present specification, the distance in the thickness direction of the first metal layer 10 from the position of the “upper surface” of the first metal layer 10 to the position of the lower surface of the second metal layer 30 (the first metal layer 10 and the second metal layer 10 The distance G) between the metal layer 30 and the metal layer 30 may be referred to as a "gap" and may be indicated as "G" in the drawings and the like. The distance G is set so that the propagation type plasmon of the first metal layer 10 and the localized type plasmon of the second metal layer 30 can interact.

  The distance G [nm] between the first metal layer 10 and the second metal layer 30 has a preferred range for each specific condition. Details of this will be described later.

  The planar size (size) (size in the direction orthogonal to the height direction of the dielectric column 20) of the dielectric column 20 can cut the dielectric column 20 by a plane parallel to the height direction. It refers to the length of the section in the specific direction, and is, for example, 5 nm or more and 200 nm or less. For example, when the shape of the dielectric column 20 is a cylinder whose central axis is in the height direction, the size (diameter of the column) of the dielectric column 20 is 10 nm or more and 200 nm or less, preferably 20 nm or more and 150 nm or less More preferably, it is 25 nm or more and 100 nm or less, and still more preferably 30 nm or more and 72 nm or less. Furthermore, the planar size (dimension) of the top surface of the dielectric pillar 20 may be larger or smaller than the planar size of the second metal layer 30 described later.

  The height of the dielectric column 20 (the distance from the position of the “lower surface” of the first metal layer 10 to the position of the lower surface of the second metal layer 30 in the thickness direction of the first metal layer 10) is the first metal There is no particular limitation as long as the propagating plasmon of the layer 10 and the localized plasmon of the second metal layer 30 can interact. Also, the height of the dielectric column 20 may be a height at which high-order interference effects can be used. The height of the dielectric pillar 20 is, for example, 1 nm to 1 μm, preferably 5 nm to 500 nm, more preferably 10 nm to 100 nm, still more preferably 15 nm to 80 nm, particularly preferably 20 nm to 60 nm. And set so that the interaction and interference effects can be obtained.

  In the present specification, the distance in the thickness direction of the first metal layer 10 from the position of the “upper surface” of the first metal layer 10 to the position of the lower surface of the second metal layer 30 is referred to as “gap”. It may be called and it may display as "G" in a drawing etc.

  In the present specification, when the shape of the dielectric column 20 is a cylinder whose central axis is in the height direction, the diameter of the dielectric column 20 is indicated as “D” in the drawings and the like. is there.

The dielectric column 20 may have a positive dielectric constant, and is formed of, for example, SiO ₂ , Al ₂ O ₃ , TiO ₂ , a polymer (resin), ITO (Indium Tin Oxide), or a composite thereof be able to. Also, the dielectric column 20 can include a dielectric, or may not include a dielectric, and in any case, it will be referred to as a dielectric column 20. Furthermore, the dielectric post 20 may be composed of a plurality of different parts (for example, a laminated structure) of different materials.

  The excitation peak frequency of the localized plasmon generated in the second metal layer 30 may shift depending on the size and the height of the dielectric column 20. Therefore, the peak of the localized plasmon may be set in the setting of the pitch P2 described later. This may be taken into account when determining the excitation wavelength.

1.3. Second Metal Layer The second metal layer 30 is provided to be separated from the first metal layer 10 in the thickness direction. The second metal layer 30 is provided so as to be electrically insulated from the first metal layer 10. The second metal layer 30 may be spaced apart from the first metal layer 10. In the examples of FIGS. 1 to 4 of the present embodiment, the second metal layer 30 is formed on the dielectric pillar 20 penetrating the first metal layer 10, whereby the first metal layer 10 and the second metal layer are formed. And 30 are spaced apart in the height direction of the dielectric post 20. This is the same as in the example of FIG.

  The shape of the second metal layer 30 is not particularly limited. For example, when projected in the thickness direction of the first metal layer 10 (in plan view from the thickness direction), the shape of the second metal layer 30 is circular, elliptical, polygonal, irregular, or a combination thereof. It can be Further, the shape of the second metal layer 30 has an overlap with the first metal layer 10 when projected in the thickness direction of the first metal layer 10 (in plan view from the thickness direction). It does not have to be.

  When the shape of the second metal layer 30 is projected in a direction orthogonal to the thickness direction of the first metal layer 10 (in the case of a side view), there is a portion along the upper surface of the dielectric post 20 However, it may be circular, oval, polygonal, irregular or a combination thereof. In the example of FIGS. 1 to 5, the second metal layer 30 is exemplified by a cylindrical (disk-like (disk-like)) shape having a central axis in the thickness direction of the first metal layer 10, and in the side view It is rectangular.

  The size T in the height direction of the second metal layer 30 (thickness T in the case of a thin film) is a section in the height direction where the second metal layer 30 can be cut by a plane perpendicular to the height direction Length of 10 nm or more and 1 mm or less, preferably 20 nm or more and 100 .mu.m or less, more preferably 30 nm or more and 1 .mu.m or less. The size (thickness) in the height direction of the second metal layer 30 may be the same as or different from the thickness of the first metal layer 10.

  In addition, the size of the second metal layer 30 in the direction orthogonal to the height direction indicates the length of a section in a specific direction in which the second metal layer 30 can be cut by a plane parallel to the height direction. More than 200 nm. For example, in the case where the shape of the second metal layer 30 is a disk shape with the central axis in the height direction, the size (diameter of the disk) of the second metal layer 30 in the first direction is 10 nm or more and 200 nm or less, The thickness is preferably 20 nm or more and 150 nm or less, more preferably 25 nm or more and 100 nm or less, and still more preferably 30 nm or more and 72 nm or less.

  In the present specification, when the shape of the second metal layer 30 is a disk whose central axis is the height direction, the diameter of the second metal layer 30 is indicated as “D” in the drawings and the like. There is a case.

  The shape and material of the second metal layer 30 are arbitrary as long as localized plasmons can be generated by the irradiation of incident light. Silver, gold, aluminum, copper, platinum, alloys thereof, and the like can be given as materials that can generate localized plasmons by light near visible light.

  The second metal layer 30 can be formed, for example, by sputtering, vapor deposition (including an aspect of inclined vapor deposition if necessary), and a method of performing patterning after such steps as required, or a microcontact printing method , Nanoimprint method or the like. Further, the second metal layer 30 may be formed by a colloid chemical method, and the colloid fine particles may be disposed on the dielectric column 20 by an appropriate method.

The second metal layer 30 has a function of generating localized plasmons in the electric field enhancing element 100 of the present embodiment. By irradiating the second metal layer 30 with incident light, which will be described later, localized plasmons can be generated around the second metal layer 30. The localized plasmons generated in the second metal layer 30 can interact with the propagating plasmons generated in the first metal layer 10 described above under certain conditions.

1.4. Arrangement of Second Metal Layers As shown in FIGS. 1 to 5, a plurality of second metal layers 30 are arranged side by side with a first pitch P 1 in the first direction together with the dielectric columns 20. Configure). Then, a plurality of the first metal rows 31 are arranged side by side at a second pitch P2 in a second direction intersecting the first direction. In addition, as the arrangement of a plurality of arrangements in the first direction, the second metal layer 30 may be continuous along the first direction, and the extent to which the first metal row 31 can be identified like, for example, a zigzag arrangement or a zigzag arrangement. In this case, the adjacent second metal layers 30 may be displaced to some extent in the second direction. In the illustrated example, the second metal layers 30 in the first metal row 31 are linearly arranged in the first direction.

  The second metal layers 30 are arranged side by side in the first direction perpendicular to the thickness direction of the first metal layer 10 in the first metal row 31. Therefore, the dielectric columns 20 described above are arranged in the first direction orthogonal to the thickness direction of the first metal layer 10, and the plurality of second metal layers 30 thereon are arranged in the first direction orthogonal to the height direction. The first metal row 31 is configured side by side. The first direction in which the second metal layers 30 are arranged may not necessarily coincide with the longitudinal direction in the case where the second metal layer 30 has a longitudinal shape in plan view (in the case of an anisotropic shape). The number of second metal layers 30 arranged in one first metal row 31 may be plural, preferably ten or more. In addition, at least one of the size (size: size), the shape, and the height (gap) of the second metal layer 30 belonging to the first metal row 31 is a localized plasmon generated in the second metal layer 30. As long as the peak wavelengths are substantially the same, they may be the same or different.

  Here, the distance between the centers of gravity in a plan view of the second metal layer 30 in the first direction in the first metal row 31 is defined as a pitch P1 (see FIGS. 2, 5 and 7). Further, in the case where the second metal layer 30 has a disk shape whose central axis is the thickness direction of the metal layer 10, the distance between the two second metal layers 30 in the first metal row 31 has a pitch P1. Is equal to the length of the disc minus the diameter of the disc. If this spacing is reduced, the effect of localized plasmons acting between particles may be increased, and the degree of enhancement may be increased. The distance between the second metal layers 30 in the first direction is 5 nm or more and 1 μm or less, preferably 5 nm or more and 100 nm or less, and more preferably 5 nm or more and 30 nm or less.

  The pitch P1 of the second metal layer 30 in the first direction in the first metal string 31 is 10 nm or more and 1 μm or less, preferably 20 nm or more and 800 nm or less, more preferably 30 nm or more and less than 780 nm, still more preferably 50 nm or more and less than 700 nm It can be done.

  Although the first metal row 31 is constituted by a plurality of second metal layers 30 arranged at a pitch P1 in the first direction, distribution of localized plasmons generated in the second metal layer 30 of the first metal row 31 The strength and the like also depend on the arrangement of the second metal layer 30. Therefore, the localized plasmon interacting with the propagating plasmon generated in the first metal layer 10 is not only the localized plasmon generated in the single second metal layer 30 but also the first plasmon of the second metal layer 30. It is a localized plasmon in which the arrangement in the metal string 31 is considered.

  As shown in FIGS. 1 to 5, the first metal rows 31 are arranged side by side at a pitch P2 in the thickness direction of the first metal layer 10 and in a second direction intersecting the first direction. The number of the first metal rows 31 may be plural, as long as it is plural, preferably ten or more.

Here, the distance between the centers of gravity in the second direction of the adjacent first metal rows 31 is defined as a pitch P2 (see FIGS. 2, 3, 5 and the like). The pitch P2 between the first metal strings 31 is set according to the conditions described in “1.4.1. Propagation plasmon and localized plasmon” below, and is, for example, 10 nm or more and 10 μm or less, preferably 20 nm 2 μm or less, more preferably 3
The thickness can be 0 nm or more and 1500 nm or less, more preferably 60 nm or more and 1310 nm or less, and particularly preferably 60 nm or more and 660 nm or less.

  Note that a line along the extending first direction of the first metal row 31 and two second metal layers 30 respectively belonging to the adjacent first metal row 31, the two second metal layers 30 closest to each other The angle formed by the connecting line is not particularly limited, and may or may not be perpendicular. For example, as shown in FIG. 2, the angle formed by the two may be a right angle, and as shown in FIG. 5, the angle formed by both may not be a right angle. That is, when the arrangement of the second metal layer 30 viewed from the thickness direction is regarded as a two-dimensional lattice in which the position of the second metal layer 30 is a lattice point, the irreducible basic unit lattice has a rectangular shape. Alternatively, the shape may be a parallelogram. In addition, a line along the extending first direction of the first metal row 31 and two second metal layers 30 respectively belonging to the adjacent first metal rows 31, the two second metal layers 30 closest to each other When the angle between the connecting line and the line is not perpendicular, the pitch between the two second metal layers 30 which are the two second metal layers 30 respectively belonging to the adjacent first metal rows 31 and which are closest to each other May be set as the pitch P2.

  In the electric field enhancing element of this embodiment, as shown in FIGS. 7 and 8, the second metal row 32 (metal row) in which a plurality of second metal layers 30 are arranged in the first direction at the third pitch P3 is obtained. It may further include. The second metal rows 32 are arranged at the second pitch P2 in the second direction, and are alternately arranged in the first metal row 31 and the second direction.

  The second metal row 32 may have the same configuration as the first metal row 31 or may have a different configuration. The second metal rows 32 may be arranged one by one with respect to the first metal row 31 or may be arranged with respect to the first metal rows 31. Furthermore, the distance (pitch P5) in the second direction between the second metal row 32 and the first metal row 31 can be 1% or more and 50% or less of the pitch P2. The pitch P5 can be set independently of the pitch P1 of the second metal layer 30 in the first direction.

  When the plurality of second metal rows 32 are disposed, they may be spaced apart from each other in the second direction at a distance of 1% or more and 50% or less of the pitch P2. The second metal row 32 has a configuration similar to that of the first metal row 31 and is disposed at a position 50% away from the first metal row 31 in the second direction by 50% of the pitch P2 In the case where the pitch P5 is a half of the pitch P2), the first metal row 31 is the same as in the case where the first metal row 31 is disposed at a half pitch of the pitch P2. , And the first metal string 31. Furthermore, when the second metal row 32 is disposed at a distance of 50% or less of the pitch P2 in the second direction from the first metal row 31 (when the pitch P5 is less than or equal to half the pitch P2) The second metal row 32 and the first metal row 31 can be regarded as one metal row (for example, the first metal row 31) as a pair.

  The second metal layer 30 belonging to the first metal row 31 and the second metal layer 30 belonging to the second metal row 32 have at least one of a size (size: size), a shape, and a height, As long as the peak wavelengths of localized plasmons generated in the metal layer 30 substantially coincide with each other, they may be the same or different.

7 and 8 are schematic views showing an example of the second metal row 32. As shown in FIG. FIG. 7 shows an example of an electric field enhancing element 200 including a second metal row 32 in which a plurality of second metal layers 30 are arranged in a first direction at a third pitch P3 having the same size as the first pitch P1. FIG. FIG. 8 shows an example of an electric field enhancing element 250 including a second metal row 32 in which a plurality of second metal layers 30 are arranged in the first direction at a third pitch P3 different in size from the first pitch P1. FIG. Thus, the pitch P3 may be the same as or different from the pitch P1. Furthermore, when a plurality of second metal rows 32 are provided, the pitch P3 in each row may be the same or different.

  Also in the electric field enhancing element 200 and the electric field enhancing element 250 according to such a modification, similarly to the electric field enhancing element 100 described above, the light is enhanced with a very high enhancement based on the plasmon excited by light irradiation. Can. In addition, according to the analysis device provided with such an electric field enhancing element, the degree of freedom in adjusting the enhancement degree profile of the electric field enhancing element to the wavelength of the scattered light depending on the substance to be analyzed is increased. Can. This makes it possible to exert a sufficiently high plasmon enhancement effect on a wide range of analytes.

  In the example of FIG. 7, the second metal row 32 has the same configuration as the first metal row 31. That is, the second metal layer 30 belonging to the second metal row 32 has the same shape as the second metal layer 30 belonging to the first metal row 31, and the pitches aligned in the first direction are the same for both. (Ie, pitch P1 = pitch P3). Further, in the case of this example, the second metal layer 30 of the first metal row 31 and the second metal layer 30 of the second metal row 32 are disposed so as to be closest to each other (the positions in the first direction are aligned). It is done. However, the second metal layer 30 belonging to the second metal row 32 and the second metal layer 30 belonging to the first metal row 31 may be arranged with the position of the second metal layer 30 shifted in the first direction.

  Further, in the case of arranging the first metal row 31 in which the second metal layers 30 are arranged at the pitch P1 in the first direction and the second metal row 32 in which the second metal layers 30 are arranged at the pitch P1 in the first direction, Similar effects to the case where the first metal rows 31 are arranged in the second direction at a half pitch of the pitch P2 can be obtained. That is, in this case, although depending on the separation distance in the second direction between the first metal row 31 and the second metal row 32, for example, although the degree of enhancement decreases, the peak wavelength characteristics become broad and the hot spot density The effect of doubling the (HSD) can be expected.

  Further, in the example of FIG. 8, the second metal row 32 is configured to be different in shape and pitch from the first metal row 31. That is, the second metal layer 30 belonging to the second metal row 32 has a shape different from that of the second metal layer 30 belonging to the first metal row 31, and the pitch aligned in the first direction is the same as that of the first metal row 31. The pitch P1 and the pitch P3 of the second metal row 32 are different from each other (that is, pitch P1 <pitch P3).

  The examples shown in FIG. 7 and FIG. 8 each show an example, and such a second metal row 32 is appropriately selected in consideration of, for example, the excitation wavelength to be irradiated, the wavelength of Raman scattered light, etc. Can be placed.

  The distance between the centers of gravity in the second direction of the adjacent first metal rows 31 is defined as the second pitch P2 (see FIGS. 2, 5, 7, 8: in the example of FIGS. 7 and 8, the first metal rows 31 And the second metal row 32 are regarded as one metal row, and the distance between the centers of gravity in the second direction of the metal rows is defined as the second pitch P2). The second pitch P2 between the metal strings 31 is set according to the conditions described in “1.4.1. Propagation plasmon and localized plasmon” below, and is, for example, 10 nm or more and 10 μm or less, preferably 20 nm The thickness can be 2 μm or less, more preferably 30 nm or more and 1500 nm or less, still more preferably 60 nm or more and 1310 nm or less, and particularly preferably 60 nm or more and 660 nm or less.

1.4.1. Propagation Type Plasmon and Localized Plasmon First, the propagation type plasmon will be described. FIG. 9 is a graph of dispersion relation showing dispersion curves of incident light, silver and gold. Usually, even if light is incident on the first metal layer 10 at an incident angle (irradiation angle θ) of 0 to 90 degrees, no propagation type plasmon is generated. For example, in the case where the first metal layer 10 is made of Ag, as shown in FIG. 9, the dispersion curve of the light line (LightLine) and the SPP of Ag does not have an intersection point (the ones having the same peripheral refractive index) in the case of). In addition, even if the refractive index of the medium through which light passes changes, the SPP of Ag also changes according to the refractive index of the periphery, so there is also no intersection point. In order to give rise to the propagation type plasmon with an intersection point, a metal layer is provided on the prism as in the Kretschmann arrangement, and the wave number of incident light is increased by the refractive index of the prism, or the wave number of the light line is determined by the diffraction grating. There is a way to increase it. FIG. 9 is a graph showing the dispersion relationship (in which the vertical axis is the angular frequency (ω [eV]) and the horizontal axis is the wave number vector (k [eV / c])).

  The angular frequency ω [eV] on the vertical axis of the graph in FIG. 9 has a relationship of λ [nm] = 1240 / ω [eV], and can be converted to a wavelength. Also, the wave number vector k [eV / c] on the horizontal axis of the graph has a relationship of k [eV / c] = 2π · 2 / (λ [nm] / 100). Therefore, for example, when λ = 600 nm, k = 2.09 [eV / c]. The irradiation angle is an irradiation angle of incident light, and is an inclination angle from the thickness direction of the first metal layer 10 or the height direction of the second metal layer 30.

FIG. 9 shows the dispersion curves of SPP of Ag and Au, but in general, the angular frequency of incident light incident on the first metal layer 10 is ω, the speed of light in vacuum is c, and the first metal layer 10 The dispersion curve of SPP of the metal is expressed by the equation (8), where ε (ω) is the dielectric constant of the metal constituting the metal layer and ε is the dielectric constant around the upper surface of the first metal layer 10.
K _SPP = ω / c [ε · ε (ω) / (ε + ε (ω))] ^1/2 (8)
Given by

On the other hand, the angle of incidence from the incident direction of incident light and the inclination angle from the thickness direction of the first metal layer 10 or the height direction of the second metal layer 30 is θ, and a virtual diffraction grating having a pitch Q is passed. The wave number K of the incident light is given by equation (9)
K = n ₁ · (ω / c) · sin θ + m · 2π / Q (m = ± 1, ± 2,,) (9)
The relationship appears as a straight line, not a curve, on the graph of the dispersion relation.

Here, n ₁ is the refractive index of the periphery on the upper surface side of the first metal layer 10, and if the extinction coefficient is κ, the real part ε ′ and the imaginary part ε ′ ′ of the relative permittivity ε at the frequency of light are , ^{_{respectively, ε '= n 1 2 -κ}} 2, given by ε "= 2n ₁ κ, if the periphery of substances transparent, because it is Kappa～0, epsilon is a real number, epsilon = n ₁ ² next , N ₁ = ε ^1/2 .

In the dispersion relation graph, when the dispersion curve of the metal SPP (the above equation (8)) and the straight line of the diffracted light (the above equation (9)) have an intersection, the propagation plasmon is excited. That is, when the relationship of K _SPP = K is established, the propagation type plasmon is excited in the first metal layer 10.

Therefore, the following formula (2) is obtained from the above formulas (8) and (9),
(.Omega. / C). {. Epsilon..epsilon. (. Omega.) / (. Epsilon. +. Epsilon. (. Omega.)) ^1/2 = .epsilon.1 ^{/ 2} (.omega. / C) .sin .theta. + 2 m.pi./Q (m = 1,2,2,) ... (2)
It is understood that propagating plasmons are excited in the first metal layer 10 if the relationship of this equation (2) is satisfied. In this case, in the example of SPP of Ag in FIG. 9, the inclination and / or intercept of the light line can be changed by changing θ and m, and the light line relative to the dispersion curve of SPP of Ag The straight lines of can be crossed.

Next, localized plasmons will be described. The conditions for causing the second metal layer 30 to generate localized plasmons are determined by the real part of the dielectric constant:
Real [ε (ω)] = − 2ε (10)
Given by The refractive index n ₂ of the peripheral second metal layer 30 1 to the epsilon = n ₂ ^{2-kappa 2} = 1 Since, Real [ε (ω)] = - 2, and becomes.

FIG. 10 is a graph showing the relationship between the dielectric constant of Ag and the wavelength as an example. For example, although the dielectric constant of Ag is as shown in FIG. 10, localized plasmons are excited at a wavelength of about 366 nm or more, but a plurality of Ag structures approach in nano order, or an Ag structure When the (second metal layer 30) and the Ag film (the first metal layer 10) are arranged to be separated by the SiO ₂ layer (dielectric column 20), excitation of localized plasmons is caused by the influence of the gap. The peak wavelength is red shifted (shifted to the long wavelength side). The amount of shift depends on the size, thickness, spacing, pitch of the Ag structure, and the dimensions of the height of the dielectric column 20 (gap G), but the localized plasmon peaks at, for example, 500 nm to 900 nm. It shows wavelength characteristics.

  In addition, localized plasmons, unlike propagating plasmons, are plasmons that have no velocity and do not move, and when plotted on a dispersion relationship graph, the slope is zero, that is, ω / k = 0.

  FIG. 11 is a graph showing the dispersion relationship of metal (Ag, Au) when the peripheral refractive index is 1, the dispersion relation of localized plasmons and incident light. The electric field enhancing element 100 of the present embodiment obtains a very large degree of enhancement of the electric field by electromagnetically coupling (propagating plasmons and localized plasmons). That is, in the graph of the dispersion relation, the electric field enhancing element 100 according to the present embodiment does not set the intersection point of the straight line of the diffracted light and the dispersion curve of the metal SPP as an arbitrary point, but the second metal layer 30 (second One of the features is to make both intersect in the vicinity of the point giving the maximum or maximum enhancement degree in the localized plasmon generated in one metal string 31).

  In other words, in the graph of the dispersion relationship, in the electric field enhancing element 100 of the present embodiment, the dispersion curve of the metal SPP and the localized plasmon generated in the second metal layer 30 (the first metal string 31) are maximal or maximal It is designed so that the straight line of diffracted light passes near the point of intersection with the angular frequency of incident light (in the graph of the dispersion relation in Figure 11, a line parallel to the horizontal axis attached to LSP) giving an enhancement. Ru.

  Here, in the vicinity of the intersection point, when converted to the wavelength, it is within the wavelength range of about ± 10% of the wavelength of the incident light, or ± P1 of the wavelength of the incident light (the second metal layer 30 It is in the range of the wavelength of the length about [width of the pitch P1 in the 1st metal row 31].

  In the above formulas (8), (9) and (2), the angular frequency of the incident light incident on the first metal layer 10 is ω, and the condition for exciting the propagation type plasmons is shown. In order to generate a hybrid (interaction) between the in-place plasmon and the in-progress plasmon, in the electric field enhancing element 100 of this embodiment, ω in the above formulas (8), (9) and (2) is This is the angular frequency of the incident light giving the maximum or maximum enhancement in localized plasmons generated in the second metal layer 30 (the first metal string 31) or the angular frequency in the vicinity thereof.

  Therefore, when the angular frequency of the localized plasmon excited in the first metal string 31 is ω, if the above equation (2) is satisfied, a hybrid of the localized plasmon and the propagating plasmon is generated. Can.

Therefore, the angular frequency of the localized plasmon generated in the first metal row 31 in which the second metal layers 30 are arranged at the pitch P1 is ω, and in the dispersion relationship graph, the position of ω of the dispersion curve of the metal SPP If a straight line of diffracted light (order m) diffracted by being incident on a virtual diffraction grating with a pitch Q at an irradiation angle θ passes in the vicinity (if equation (2) is satisfied), localization occurs. It is possible to generate a hybrid of the type plasmon and the propagation type plasmon and to obtain an extremely large degree of enhancement. In other words, in the graph of the dispersion relation shown in FIG. 11, by changing the inclination and / or intercept of the light line and changing the light line so as to pass near the intersection of SPP and LSP, the localized type Hybrids of plasmons and propagating plasmons can be generated, and an extremely large degree of enhancement can be obtained.

1.4.2. Pitch P2
The pitch P2 between the first metal rows 31 (metal rows) is set as follows. When the first-order diffracted light (m = 0) is used at normal incidence (incident angle θ = 0), equation (2) can be satisfied by setting the pitch P2 as the pitch Q. However, depending on the selected incident angle θ and the order m of diffracted light, the pitch Q which can satisfy the equation (2) will have a width. In this case, the incident angle θ is preferably a tilt angle from the thickness direction to the second direction, but may be a tilt angle in the direction including the component in the first direction.

Therefore, taking into consideration of being in the vicinity of the above intersection point (width of ± P1 or width of ± 10%), the range of the row pitch P2 which can generate a hybrid of localized plasmon and propagating plasmon is Formula (11) or Formula (12),
Q−P1 ≦ P2 ≦ Q + P1 (11)
Q-P2 / 10 ≦ P2 ≦ Q + P2 / 10 (12)
It becomes.

  On the other hand, although the pitch P2 is the pitch in the second direction between the first metal rows 31 (metal rows), the pitch between the two second metal layers 30 belonging to the adjacent first metal rows 31 is two. Depending on how the second metal layer 30 is selected, the line connecting these can be inclined with respect to the second direction. That is, the two second metal layers 30 belonging to the adjacent first metal row 31 can be selected so as to have an interval longer than the pitch P2. In FIG. 2, an auxiliary line for describing this is drawn, and along the direction inclined with respect to the second direction, two second metal layers 30 separated by a distance longer than the pitch P2 are It can be selected from the matching first metal string 31. As described above, since the adjacent first metal row 31 is the first metal row 31 having the same configuration as each other, the arrangement of the second metal layer 30 viewed from the thickness direction is the position of the second metal layer 30 It can be regarded as a two-dimensional lattice with lattice points. Then, in this two-dimensional grating, there is a gap (diffraction grating) longer than the pitch P2.

  Therefore, in the matrix of the second metal layers 30 arranged at the pitch P1 and the pitch P2, diffracted light can be expected by the diffraction grating having a distance larger than the pitch P2. Therefore, the inequality on the left side of the equation (11) and the equation (12) can be P1 ≦ P2. In other words, in the equations (11) and (12), even if the row pitch P2 is smaller than Q−P 2/10 or Q−P 1, a diffraction grating having a pitch Q that can satisfy the equation (2) can be obtained. Because they can be present, hybrids of localized and propagating plasmons can be generated. Therefore, the pitch P2 may be a value smaller than Q-P1 or Q-P2 / 10, and it suffices to satisfy the relationship of P1 ≦ P2.

  From the above, if the pitch P2 between the first metal string 31 (metal string) in the electric field enhancing element 100 of the present embodiment satisfies the relationship of the following formula (1) or the formula (13), localized plasmons It is possible to generate a hybrid between the and the propagation type plasmons.

P1 ≦ P2 ≦ Q + P2 / 10 (1)
P1 ≦ P2 ≦ Q + P1 (13)
1.4.3. Structural Features and Hot Spot Generation Positions FIG. 12 is a diagram schematically showing an enlarged main part of the electric field enhancing element 100 of the present embodiment in comparison with a gap type surface plasmon polariton (GSPP) model. 12 (a) shows the structure of the main part of the electric field enhancing element according to the present invention, and FIG. 12 (b) is a schematic view showing the main part of a typical GSPP structure. As shown in FIG. 12A, in the electric field enhancing element 100 of the present embodiment, when the contour of the second metal layer 30 in plan view is the same as the contour of the dielectric post 20, the second metal layer 30 is formed. It is an end in plan view, and the lower part on the substrate 1 side (hereinafter, the part may be referred to as the “bottom end” of the second metal layer 30 (indicated by symbol B in the figure)) is the measurement. As compared with the corresponding position of the GSPP model shown in FIG. 12B, the object M to be targeted is more easily in contact.

That is, in the electric field enhancing element 100 of the present embodiment, a structure such as a dielectric is provided outside the outline of the second metal layer 30 in plan view, and in the region under the second metal layer 30 in cross sectional view There is no body. On the other hand, in the GSPP model, a dielectric layer (SiO ₂ layer) is present outside the outline of the Ag particle in plan view and in the region under the Ag particle in a cross sectional view. Therefore, when the object M (virus or compound) to be measured approaches the second metal layer 30, the bottom end B can be easily contacted in the electric field enhancing element 100 of the present embodiment, but GSPP In the case of the model, the path for approaching is narrowed by the presence of the SiO ₂ layer at the position corresponding to the bottom end of the Ag particle, and it is difficult to contact since it is difficult to enter.

  On the other hand, when the second metal layer 30 is arranged to satisfy the above conditions, the hot spot HS (a region exhibiting a high degree of electric field enhancement) generated near one second metal layer 30 is the bottom end B and the second metal It occurs at the upper end (top end T) of the end of the layer 30 in plan view and on the side away from the substrate 1. Also in the GSPP model, it occurs at positions corresponding to the bottom and top ends of Ag particles, respectively (see FIG. 12).

  Although the magnitude of the strength of the hot spot may be large and small depending on various conditions at the bottom end B and the top end T, in the electric field enhancing element 100 of the present embodiment, the object M contacts both hot spots HS. Since this can be performed, a larger value can be obtained as the overall electric field enhancement (total) as compared to the GSPP model in which the object M is less likely to contact the position corresponding to the bottom end.

  Therefore, according to the electric field enhancing element 100 of the present embodiment, not only a small sample analysis of nano order such as a rare gas but also a measurement substance having a large size of 5 nm or more, such as a virus with a diameter of 20-100 nm, for example The sensitivity can be quantified and quantified.

1.5. The relationship between the arrangement of the second metal layer and the propagating surface plasmon and the localized surface plasmon FIG. 13 shows the arrangement of the second metal layer, LSP (Lossified Surface Plasmon Resonance), and PSP (PSPR: Propagating Surface Plasmon Resonance). Is a diagram for explaining the relationship between In FIG. 13, (a) schematically shows a plane of the electric field enhancing element, (b) schematically shows a cross section taken along line B-B of (a) of the electric field enhancing element, (c ) Schematically shows a cross section taken along the line C-C of (a) of the electric field enhancing element.

  Here, in the LSP generated around the second metal layer, a mode (hereinafter referred to as “PPGM” (Particle-Particle Gap Mode)) generated between the adjacent second metal layers, and the second metal layer and the second metal layer. It is known that there are two types of modes (hereinafter referred to as “PGM-Mirror Gap Mode”) that occur between one metal layer (which also has the function of a mirror) (hereinafter referred to as “PMGM”) (FIG. 13). reference).

Both LSP of the two types of PPGM and PMGM are generated when excitation light is incident to the electric field enhancing element. Among these, LSP of PPGM becomes higher in strength as the second metal layer approaches (the distance between the second metal layers decreases). In addition, the strength of LSP of PPGM becomes higher as the component (polarization component) of the vibration of the electric field of the excitation light increases in the direction in which the approaching second metal layers are arranged. On the other hand, the LSP of the PMGM mode is not largely affected by the arrangement of the second metal layer or the polarization direction of the excitation light, and irradiation of the excitation light results in an interval between the second metal layer and the first metal layer 2) formed under the metal layer). And PSP is a plasmon which propagates near the surface of the first metal layer, and excitation light is incident on the first metal layer, thereby making the vicinity of the surface of the first metal layer regardless of the direction of polarization of the incident light. It propagates isotropically.

  FIG. 13 schematically shows a comparison of the Hybrid structure, the Basic structure, and the one-line structure. The polarization direction of the excitation light irradiated to the electric field enhancing element is indicated by an arrow in the figure. The terms “Basic structure, one-line structure,” and “Hybrid structure” are coined terms used to distinguish each other in the present specification, and their meanings will be described below.

  First, the Basic structure is a structure in which the second metal layers are densely arranged in plan view, and LSPR of PPGM and LSPR of PMGM are excited by the irradiation of the excitation light. In this example, LSPR of PPGM occurs at both ends of the second metal layer in the polarization direction of the excitation light, but since the basic structure has a small anisotropy of the arrangement of the second metal layer, the excitation light is polarized light Also in the case of not being generated according to the component of the electric field vector of the excitation light. In the Basic structure, the second metal layer is densely disposed due to the dispersion relation of the second metal layer. As a result, the wave number k becomes large, the wavelength at which the PSPR occurs is shifted to the shorter side, and FIG. Becomes smaller. As a result, PSPR is weak or not generated, and a schematic wavy line representing PSPR is omitted in the figure.

  Next, the one-line structure is a structure in which the second metal layer is arranged at an intermediate density between the Basic structure and the Hybrid structure in plan view. That is, the one-line structure has a relationship of P1 <P2 in the arrangement of the second metal layer 30 described above. In the one-line structure, since the arrangement of the second metal layer has anisotropy, the generated LSPR depends on the polarization direction of the excitation light. In the one-line structure, in the case of LSPR 場合 PSPR (ie, in the case of incidence of linearly polarized light in a direction along the narrow direction of the distance between the second metal layers), irradiation of the excitation light LSPR is excited. And since it is 1 line structure, as a result of the 2nd metal layer being sparsely arranged, PSPR (wave line in a figure) occurs.

  In the case of LSPR ‖ PSPR (that is, when linearly polarized light in the direction along the wide direction of the distance between the second metal layers is incident) of the one-line structure, the irradiation of the excitation light excites LSPR of PMGM. It is done. In this case, since the second metal layer in the direction along the polarization direction of the excitation light is separated, LSPR of PPGM is weak compared to the case of LSPR⊥PSPR, and is not shown in the figure. And since it is 1 line structure, as a result of the 2nd metal layer being sparsely arranged, PSPR (wave line in a figure) occurs.

  Although FIG. 13 exemplifies a mode in which a metal row is formed of one row as a one-line structure, as described above, the metal rows include a plurality of metal rows (a first metal row and a first metal row Even in this case, if it is a relationship of P1 <P2, it can be classified into a one-line structure. And, even in this case, the modes of LSPR of PPGM, LSPR of PMGM, and excitation of PSPR are similar to the one-line structure in which the metal string is composed of one metal string (first metal string).

The hybrid structure is a structure in which the second metal layer is disposed sparsely as compared to the basic structure in plan view, and the irradiation of the excitation light excites the LSPR of PMGM. In this example, since PPMR's LSPR is separated from the second metal layer, it is weakly generated in comparison with the Basic structure, and is not shown in the figure. In the hybrid structure, as a result of the second metal layers being arranged sparsely, PSPR (wave line in the figure) is generated in both the first direction and the second direction regardless of the polarization direction of the incident light.

  Although FIG. 13 describes the case where polarized light is incident, in any structure, when excitation light or circularly polarized light which is not polarized is incident, the component in the vibration direction of the electric field is input. In response, the above-described SPRs occur.

  The overall SPR intensity (field enhancement) in each structure is associated with the sum (or product) of the SPRs generated in each. The degree of contribution of PSPR to the intensity of the entire SPR increases in the order of Basic structure <1 line structure <Hybrid structure when the shape and size of the second metal layer are the same in each structure. In addition, the degree of contribution of LSPR (PPGM and PMGM) to the strength of all SPRs is the hybrid structure from the viewpoint of the density (HSD) of the second metal layer when the shape and size of the second metal layer are the same in each structure. It becomes larger in the order of 1 line structure <Basic structure. Furthermore, focusing on HSD and PPGM's LSPR, the degree of contribution of PPGM's LSPR to the intensity of all SPRs increases in the order of Hybrid structure <1 line‖structure <1 line⊥structure <Basic structure.

  The Hybrid structure has the strongest strength of the PSPR as compared to other structures, and the largest contribution of the PSPR to the overall degree of enhancement. Then, although the strength of the PPGM LSPR is small and the density of the second metal layer is also small, the PMGM LSPR and PSPR interact electromagnetically strongly (synergetically couple).

  On the other hand, the one-line wedge structure and the one-line wedge structure are structures in which LSPRs and PSPRs of intermediate intensity strongly interact (synergistically combine) compared to the other structures. Further, in the one-line cage structure, LSPR and PSPR of PPGM with high strength interact electromagnetically strongly. Further, in the one-line wedge structure, PMGM's LSPR and PSPR generated at an intermediate density (higher than the hybrid structure) interact electromagnetically strongly.

  Therefore, the 1-line ridge structure and the 1-line ridge structure differ in at least the density of the second metal layer and the contribution ratio of each SPR from the Basic structure in which PSPR hardly occurs and the Hybrid structure in which LSPR of PPGM hardly occurs. It can be said that the mechanism of the electric field enhancement is different.

  In each structure, by changing the size of the second metal layer (for example, the diameter or thickness in plan view), the contribution of PSPR to the strength of all SPRs, or the LSPR of PPGM to the strength of all SPRs. The degree of contribution changes.

  The electric field enhancing element 100 according to the present embodiment has a hybrid structure (P1 = P2) or a one-line structure (P1 <P2), and as shown in FIG. 13, the plurality of second metal layers 30 is a first metal It has a periodic arrangement capable of exciting the PSP propagating near the surface of the layer 10. Then, the electric field enhancing element 100 sets the height G (gap) between the first metal layer 10 and the second metal layer 30 so that the PSP and the LSP are electromagnetically coupled. By designing, as shown in FIG. 13, PSP excited in the first metal layer and LSP excited in the second metal layer can be electromagnetically interacted.

1.6. The relationship between the arrangement of the second metal layer and the degree of enhancement As described above, the arrangement of the second metal layer 30 in the electric field enhancing element 100 according to this embodiment is a hybrid structure of P1 = P2 or one line of P1 <P2. Belongs to the structure. The electric field enhancing element 100 according to the present embodiment depends on the arrangement of the second metal layer 30, and the distance G between the preferred first metal layer 10 and the second metal layer 30 as well as the preferred substrate 1. There is a refractive index n. Hereinafter, this will be described separately.
(Ii) When the arrangement of the second metal layer 30 is a hybrid structure or a one-line structure, that is,
P1 ≦ P2 ≦ Q + P2 / 10 (1) or
P1 ≦ P2 ≦ Q + P1 (13) The first metal layer 10 and the second metal are satisfied if PSPR occurs strongly and interaction with LSPR is relatively large (in the case of not having a Basic structure) When the distance G [nm] between the layer 30 and the layer 30 satisfies the relationship of the following formula (3), a high degree of electric field enhancement can be obtained.

20 [nm] <G. [epsilon] ¹ / 2.cos [theta] <270 [nm]. [Lambda] i / 785 [nm] (3)
[In the formula (3), ε is the dielectric constant around the first metal layer 10, θ is the irradiation angle of incident light, and the inclination angle from the thickness direction of the first metal layer 10, λi is the incident angle Represents the wavelength [nm] of light. ]
(I-ii) When the disposition of the second metal layer 30 is a hybrid structure or a one-line structure, ie,
P1 ≦ P2 ≦ Q + P2 / 10 (1) or
P1 ≦ P2 ≦ Q + P1 (13) When PSPR is strongly generated and interaction with LSPR is relatively large (in the case of not having a Basic structure), the refractive index of substrate 1 is the following formula ( A high degree of electric field enhancement can be obtained by satisfying the relationship 4).

0.9 · ε ^1/2 ≦ n ≦ 1.1 · ε ^1/2 (4)
[In the formula (4), ε represents the dielectric constant of the periphery of the first metal layer 10, and n represents the refractive index of the substrate 1. ]
In the case of (Ii) and (I-ii), the incident light may or may not be polarized light, and in the case of polarized light, the incident light may be in the first direction. The light may be linearly polarized light, linearly polarized light in the second direction, circularly polarized light, or a combination thereof. That is, as described above, PSPR and LSPR can be generated by any incident light, and a high degree of electric field enhancement due to the interaction between the two can be obtained.
(II-i) When the arrangement of the second metal layer 30 has a one-line structure, that is,
P1 <P2 ≦ Q + P1 (5) or
P1 <P2 ≦ Q + P2 / 10 (6), and the incident light is linearly polarized light in the first direction (linearly polarized light in the direction along the extending direction of the first metal row 31) (this is the case) The distance G [nm] between the first metal layer 10 and the second metal layer 30 has a high degree of electric field enhancement by satisfying the relationship of the following formula (3). You can get it.

20 [nm] <G. [epsilon] ¹ / 2.cos [theta] <270 [nm]. [Lambda] i / 785 [nm] (3)
[In the formula (3), ε is the dielectric constant around the first metal layer 10, θ is the irradiation angle of incident light, and the inclination angle from the thickness direction of the first metal layer 10, λi is the incident angle Represents the wavelength [nm] of light. ]
(II-ii) When the arrangement of the second metal layer 30 has a one-line structure, that is,
P1 <P2 ≦ Q + P1 (5) or
P1 <P2 ≦ Q + P2 / 10 (6) and the incident light is linearly polarized light in the first direction (linearly polarized light in the direction along the extending direction of the first metal row 31) (1 When the refractive index of the substrate 1 satisfies the relationship of the following equation (4), a high degree of electric field enhancement can be obtained.

0.9 · ε ^1/2 ≦ n ≦ 1.1 · ε ^1/2 (4)
[In the formula (4), ε represents the dielectric constant of the periphery of the first metal layer 10, and n represents the refractive index of the substrate 1. (III-i) When the arrangement of the second metal layer 30 has a one-line structure, that is,
P1 <P2 ≦ Q + P1 (5) or
P1 <P2 ≦ Q + P2 / 10 (6) and at the same time, linearly polarized light in the second direction (linearly polarized light in the direction intersecting the extending direction of the first metal row 31 (metal row)) In the case (this is referred to as “one line ‖”), the distance G [nm] between the first metal layer 10 and the second metal layer 30 satisfies the relationship of the following formula (7) A high degree of electric field enhancement can be obtained.

20 [nm] <G. [epsilon] ¹ / 2.cos [theta] <= 220 [nm]. [Lambda] i / 785 [nm] (7)
[In the formula (7), ε is a dielectric constant around the first metal layer 10, θ is an irradiation angle of incident light, and an inclination angle from the thickness direction of the first metal layer 10, λi is an incident angle Represents the wavelength [nm] of light. ]
The numerical values “20 [nm]”, “270 [nm]”, “220 [nm]”, and “785 [nm]” described in this section are all obtained experimentally by the inventors. It is an experience value, which is one of the important parameters of the present invention. By satisfying the above conditions (Ii) to (III-i), the degree of electric field enhancement of the electric field enhancing element 100 of this embodiment becomes extremely high.

  Since each equation holds even if the wavelength of the excitation light changes (λi / 785 [nm]) multiplied by the upper limit value in the above equations (3) and (7), a correction for expressing this It is a term. These values and correction terms are proved in the following experimental examples.

1.7. Enhancement The relationship between the electric field Ex in the X direction (first direction) and the magnitude of the electric field Ez in the Z direction (thickness direction), that is, the vector changes according to the mesh position of FDTD calculation. When linearly polarized light in the X direction is used as excitation light, the electric field Ey in the Y direction (second direction) can be almost ignored. Therefore, the degree of enhancement can be grasped using the square root of the sum of squares of Ex and Ez, that is, SQRT (Ex ² + Ez ² ). In this way, they can be compared to one another as scalars of the local electric field.

  In the experimental examples and figures in the present specification, the first direction may be referred to as the X direction, and that direction may be expressed by the notation “X”. Also, the second direction may be referred to as the Y direction, and that direction may be expressed by the notation “Y”. Also, the thickness direction of the element may be referred to as the Z direction, and that direction may be expressed by the notation "Z".

SERS (Surface Enhancement Raman Scattering) effect uses Hot Spot Density (HSD) as SERS EF (Enhancement Factor), where the electric field enhancement degree at the wavelength of excitation light is Ei, the electric field enhancement degree at the wavelength after Raman scattering is Es The following formula (a)
SERS EF = Ei ² · Es ² · HSD (a)
Is represented by

Here, for example, at an excitation wavelength of 600 nm, Stokes scattering of 1000 cm ⁻¹ or less has a scattering wavelength of 638 nm at the maximum, and the difference from the excitation wavelength is 40 nm or less,
Ei ² · Es ² E Emax ⁴
(Emax is the maximum enhancement).

Therefore, the formula (a) is represented by the following formula (b)
SERS EF = Emax ⁴ · HSD (b)
And can be put.

In other words, SERS (surface enhanced Raman scattering) can be considered as the fourth power of the electric field enhancement degree by plasmons multiplied by the hot spot density.

When considering the degree of enhancement of the electric field enhancing element 100, it is necessary to consider so-called hot spot density (HSD). That is, the degree of light enhancement by the electric field enhancing element 100 depends on the number of second metal layers 30 per unit area of the electric field enhancing element 100. In the electric field enhancing element 100 of the present embodiment, the degree of SERS enhancement of the electric field enhancing element 100 is proportional to Emax ⁴ / (P1 · P2) in consideration of HSD.

1.8. Incident Light The wavelength of the incident light to be input to the electric field enhancing element 100 is not limited as long as LSP and PSP can be generated, and may be an electromagnetic wave including ultraviolet light, visible light and infrared light. In the present embodiment, the incident light may be linearly polarized light. Further, even if the incident light is linearly polarized light in the same direction as the first direction of the electric field enhancing element 100 (the extending direction of the first metal row 31), the electric field is the second direction of the electric field enhancing element 100 (second It may be linearly polarized light in the same direction as the direction in which the 1 metal row 31 is arranged. The incident light may be circularly polarized light. Furthermore, it is also possible to design the electric field enhancing element 100 to obtain a very large degree of light enhancement by combining incident light with different directions of polarization as appropriate.

1.9. Production of Electric Field Enhancement Element The electric field enhancement element 100 of the present embodiment can be manufactured, for example, through a process of injection molding using a Ni mold. Specifically, a silicon wafer is thermally oxidized, a resist is coated on the surface, and a position corresponding to the dielectric column 20 is exposed by EB (electron beam) to pattern silicon oxide. Then, a Ni film is coated on the surface by electroless Ni plating or sputtering, and then Ni is electroformed. Then, when the silicon wafer is peeled off, it is possible to obtain a Ni mold provided with a recess corresponding to the arrangement and shape of the dielectric post 20.

  Then, using a Ni mold, PMMA (polymethacrylic acid) or PC (polycarbonate) is injection molded, or a UV curable resin is molded to form a structure in which dielectric columns 20 are formed on the substrate. .

  Then, a thin metal film capable of generating plasmons such as Ag, Au, Al, Cu, etc. is formed with a thickness of about 20 nm on the substrate on which dielectric column 20 is formed, using, for example, highly anisotropic ion beam sputtering or the like. Then, the electric field enhancing element of this embodiment can be manufactured.

  Further, in the method of manufacturing the electric field enhancing element 100, as an example, a glass substrate is coated with a resist to a first thickness, exposed by EB (electron beam) at a position corresponding to the dielectric column 20, and etching and Post-baking can also be applied. Then, a resist is coated to a second thickness, and a position corresponding to the dielectric pillar 20 is exposed and etched. As a result, recesses of two depths are formed, and after such steps, analysis elements with different heights of the dielectric pillars 20 can be manufactured by the same process as described above.

  These manufacturing methods are all examples, and the electric field enhancing element 100 can be manufactured by any other appropriate method. Further, in the case of using the above-described manufacturing method, it is possible to easily manufacture the electric field enhancing element 100 in which the dielectric pillars 20 and the second metal layer 30 having different shapes and heights are disposed in the same element.

1.10. Operation Effect, Etc. The electric field enhancing element 100 of the present embodiment has the following features. The electric field enhancing element 100 of the present embodiment can enhance light with a very high enhancement degree and high HSD based on plasmons excited by light irradiation. Further, in the electric field enhancing element 100 of the present embodiment, the positions where the hot spots occur are the bottom end B and the top end T of the second metal layer 30, and the object M to be measured contacts these hot spots Has geometry that can. Therefore, as compared with the GSPP model in which the object M hardly contacts the bottom end, a larger value can be obtained as an overall electric field enhancement (total).

  Since the electric field enhancing element 100 of the present embodiment has a high degree of enhancement, for example, biological related substances such as bacteria, viruses, proteins, nucleic acids, various antigens / antibodies, etc. in the fields of medicine / health, environment, food, public safety etc. It can be used as a sensor for detecting various compounds including inorganic molecules, organic molecules, and polymers at high sensitivity, high accuracy, and quickly and easily. For example, the antibody is bound to the second metal layer 30 of the electric field enhancing element 100 of the present embodiment to obtain the degree of enhancement at this time, and based on the change in the degree of enhancement when the antigen binds to the antibody. You can check the presence or amount. In addition, the degree of light enhancement of the electric field enhancing element 100 of the present embodiment can be used to enhance Raman scattered light of a trace substance.

2. Analyzer FIG. 14 is a view schematically showing the main part of the analyzer 1000 of the present embodiment.

  The analysis apparatus 1000 of the present embodiment includes the above-described electric field enhancing element 100, a light source 300 for irradiating incident light to the electric field enhancing element 100, and a detector 400 for detecting light emitted from the electric field enhancing element 100. . The analyzer 1000 of the present embodiment may have other appropriate configurations not shown.

2.1. Electric field enhancing element The analyzer 1000 of the present embodiment includes an electric field enhancing element 100. The electric field enhancing element 100 is the same as the above-described electric field enhancing element 100, so the detailed description will be omitted.

  The electric field enhancing element 100 is responsible for the action of enhancing light and / or the action of a sensor in the analyzer 1000. The electric field enhancing element 100 may be used in contact with a sample to be analyzed by the analyzer 1000. The arrangement of the electric field enhancing element 100 in the analyzer 1000 is not particularly limited, and may be installed on a stage or the like that can be adjusted in installation angle or the like.

2.2. Light Source The analyzer 1000 of the present embodiment includes a light source 300. The light source 300 irradiates the electric field enhancing element 100 with incident light. The light source 300 is linearly polarized light (in the same direction as the first direction) linearly polarized in the first direction of the electric field enhancing element 100 (the direction in which the second metal layers 30 are aligned and the first metal row 31 extends). ), Light linearly polarized in the second direction of the electric field enhancing element 100 (the direction in which the first metal rows 31 are aligned and intersects the extending direction of the first metal rows 31) (straight line in the same direction as the second direction) Polarized light) or circularly polarized light can be irradiated.

  That is, the light source 300 irradiates the electric field enhancing element 100 with linearly polarized light in the same direction as the first direction and / or linearly polarized light in the same direction as the second direction, or to the electric field enhancing element 100 Thus, it is possible to irradiate circularly polarized light. The inclination angle θ of the incident light emitted from the light source 300 from the thickness direction of the first metal layer 10 may be appropriately changed according to the excitation condition of the surface plasmon of the electric field enhancing element 100. . The light source 300 may be installed in a goniometer or the like.

The light emitted by the light source 300 is not particularly limited as long as it can excite the surface plasmons of the electric field enhancing element 100, and can be an electromagnetic wave including ultraviolet light, visible light, and infrared light. The light emitted by the light source 300 may or may not be coherent light. Specifically, as the light source 300, a semiconductor laser, a gas laser, a halogen lamp, a high pressure mercury lamp, a xenon lamp, etc. can be appropriately provided with a wavelength selection element, a filter, a polarizer and the like.

  Furthermore, when the light source 300 includes a polarizer, a known polarizer can be used, and a mechanism for appropriately rotating the polarizer may be provided. The light from the light source 300 becomes excitation light, concentration of the electric field by the plasmon generated in the electric field enhancing element 100, so-called hot spot is generated, and weak Raman light of the substance attached to the hot spot is enhanced by the electric field of the hot spot Detection of the substance.

2.3. Detector The analyzer 1000 of the present embodiment includes a detector 400. The detector 400 detects the light emitted from the electric field enhancing element 100. As the detector 400, for example, a charge coupled device (CCD), a photomultiplier, a photodiode, an imaging plate, or the like can be used.

  The detector 400 may be provided at a position where light emitted from the electric field enhancing element 100 can be detected, and the positional relationship with the light source 300 is not particularly limited. Also, the detector 400 may be installed in a goniometer or the like.

3. Electronic Device The electronic device 2000 according to the present embodiment includes the analysis device 1000 described above, a calculation unit 2010 that calculates health care information based on detection information from the detector 400, and a storage unit 2020 that stores health care information. And a display unit 2030 for displaying health and medical information.

  FIG. 15 is a schematic view of the configuration of the electronic device 2000 of the present embodiment. The analyzer 1000 is the analyzer 1000 described above in “2. Analyzer”, and the detailed description is omitted.

  The computing unit 2010 is, for example, a personal computer or a personal digital assistant (PDA), receives detection information (such as a signal) sent from the detector 400, and performs computation based on the information. In addition, the calculation unit 2010 may control the analysis device 1000. For example, the computing unit 2010 may control the output of the light source 300 of the analyzer 1000, control of the position, etc., control of the position of the detector 400, and the like. The calculation unit 2010 can calculate health care information based on the detection information from the detector 400. Then, the health care information calculated by the calculation unit 2010 is stored in the storage unit 2020.

  The storage unit 2020 is, for example, a semiconductor memory, a hard disk drive, or the like, and may be configured integrally with the computing unit 2010. The health care information stored in the storage unit 2020 is sent to the display unit 2030.

  The display unit 2030 is configured of, for example, a display plate (such as a liquid crystal monitor), a printer, a light emitter, a speaker, and the like. The display unit 2030 displays or issues a notification so that the user can recognize the content based on the health care information or the like calculated by the calculation unit 2010.

  Health and medical information includes at least one biological substance selected from the group consisting of bacteria, viruses, proteins, nucleic acids, and antigens and antibodies, or the presence or absence of at least one compound selected from inorganic molecules and organic molecules. Or it can contain information about the quantity.

4. EXPERIMENTAL EXAMPLES Experimental examples will be shown below to further explain the present invention, but the present invention is not limited at all by the following examples. The following example is a computer simulation. Each model was calculated using FDTD simulation. In addition, incident light was linearly incident light in which the electric field was polarized in the X direction (first direction) with perpendicular incidence. The refractive index of the background was calculated with n = 1 as a vacuum or an air layer.

  In each experimental example, a model as schematically shown in FIG. 16 was used. FIG. 16 is a schematic view showing a model used for the simulation of this experimental example. The dimensions of this experimental example were designed on the assumption that an excitation wavelength of around 633 nm or around 785 nm at normal incidence was used. The model of the present experimental example assumes a substrate obtained by injection molding of PMMA (polymethacrylic acid) or PC (polycarbonate) or the like or a UV (ultraviolet) curing resin from a metal mold having a concave surface.

  Specifically, the convex portion of PMMA is formed in a shape of 80 nm D 80 nm T (G + T) (cylindrical shape having a diameter of 80 nm and a height of 80 nm), and Ag does not adhere to the side surface of the convex portion As described above, it is assumed that the Ag layer (the first metal layer 10 and the second metal layer 30) is formed to a thickness of 20 nmT by a highly anisotropic film forming method. In this case, since the difference (gap G) in height between the bottom of the Ag layer (second metal layer 30) and the top of the Ag layer (first metal layer 10) is 60 nm, in such a system, It shall be written as 60G.

(Parameters of calculation model etc.)
For the graphs and the like shown in each of the experimental examples, for example, a notation such as "X180Y600" is used. “X180Y600” means that the second metal layer is disposed at a pitch of 180 nm (first pitch P1) in the first direction (X direction) and at a pitch of 600 nm (second pitch P2) in the second direction (Y direction). Do.

  In addition, when the letters “D” and “T” are attached to the numerical value, it means that the second metal layer used in the model has a cylindrical shape with a diameter D and a thickness T. Moreover, when the symbol “G” is attached to the numerical value, it indicates that the distance G [nm] is between the first metal layer 10 and the second metal layer 30. Further, “Gap thickness” on the horizontal axis of the graph indicates the distance G [nm] between the first metal layer 10 and the second metal layer 30. Furthermore, in the case where a numerical value is written with a range such as “20-100, etc.”, for example, the numerical value is calculated taking continuous or jump (discrete) values for calculation in the relevant range. It is shown that.

  Furthermore, “Ag” or “AG” in the figure indicates that the material of the configuration to be noted is silver, and “Au” or “AU” indicates that the material of the configuration to be focused is gold It shows that it is. Further, "@" means "at the wavelength followed by @", for example, "SQRT_ @ 815 nm" means SQRT at a wavelength of 815 nm.

  In addition, although it is the meaning of the symbol (abbreviation) which characterizes each model, for example, in the case of the notation with the X180Y600 model, diffraction is performed with a repetition cycle of 180 nm pitch in the X direction and a repetition cycle of 600 nm pitch in the Y direction. It means forming a second metal layer having the role of a lattice.

  On the other hand, in the X600Y180 model, it means that the second metal layer is formed with a repetition period of 600 nm in the X direction and a repetition period of 180 nm in the Y direction. Here, the X600Y180 model is equivalent to the incidence of incident light polarized in the Y direction (second direction) in the X180Y600 model.

In the present specification, both the X180Y600 model and the X600Y180 model are referred to as a one-line model. Further, a model having a small pitch in both the X direction and the Y direction as in the X180 Y180 model is called a Basic model. Furthermore, when linearly polarized light in the X direction is incident, a model having a small pitch on the polarization direction side like the X180Y600 model is referred to as a one-line ⊥ model, and as in the X600Y180 model, in the polarization direction of the polarized light. A model with a small pitch in the orthogonal direction is referred to as a one-line ‖ model. Furthermore, as in the X600Y600 model, a model in which the pitch in both the XY directions is large and the PSP is strongly generated in the first metal layer (mirror layer) is referred to as a hybrid model.

(Summary of calculation)
The calculation was performed using FDTD soft FullWAVE of Rsoft (currently Cybernet Systems Co., Ltd.). Further, as to the conditions of the mesh used, the one not described in the figure was a 1 nm minimum mesh, and the calculation time cT was 10 μm.

At the enhancement position (hot spot), all the degrees of enhancement in the following experimental examples are represented by SQRT (E _x ² + E _z ² ) because they consist of two components of the electric fields E _x and E _z . Here, Ex indicates the electric field intensity in the polarization direction (first direction) of incident light, and Ez indicates the electric field intensity in the thickness direction. In this case, the electric field intensity in the second direction is not considered because it is small. Also, in the following, SQRT (E _x ² + E _z ² ) may be simply referred to as "SQRT".

  In addition, when surface plasmon resonance (SPR) is generated by irradiation of excitation light, absorption by resonance occurs and the reflectance decreases. Therefore, the intensity of the SPR enhanced electric field can be expressed as (1-r) using the reflectance r. There is a relation that the intensity of the enhanced electric field is stronger as the value of the reflectance r is closer to zero, so the reflectance may be used as an index of the square of the intensity (SQRT) of the SPR enhanced electric field.

4.1. Experiment 1 <Hybrid model>
In this experimental example, a dielectric pillar of PMMA is formed in a shape of 120 nm D 120 nm D at a pitch of X 600 Y 600, and a silver thin film is formed 20 nm on the entire surface by a strong anisotropic film forming method so that silver does not adhere to the side surface of the dielectric pillar. It is Since the difference in height between the bottom of the silver second metal layer and the top surface of the silver first metal layer is 100 nm, G is expressed as G = 100G.

  FIG. 17 shows the wavelength characteristics (far-field characteristics) (a) of the reflectance and the wavelength characteristics (near-field characteristics) (b) of SQRT of the model of this experimental example. As for the wavelength characteristic of the reflectance, as shown in FIG. 17A, local minimum values of a plurality of reflectances were observed. Several local minima occurred here. This is because the far-field characteristic indicates the integral value of the reflected light reflected from the electric field enhancing element. Therefore, looking at the wavelength characteristics of the top and bottom of the second metal layer in the near field and the wavelength characteristics of the holes penetrating the first metal layer shown in FIG. It turns out that it is the sum of

  Referring to the graph of FIG. 17 (b), the bottom of the second metal layer (solid line) and the top of the second metal layer (dotted line) have two peaks due to the anti-crossing vivenier by the hybrid structure I understand. On the other hand, it can be seen that the wavelength characteristic (grey line) of the hot spot of plasmon generated in the first metal layer (Ag) has two peaks.

In FIG. 18, wavelength characteristics (gray line) of hot spots of plasmons generated in the first metal layer (Ag) and XZ (0) placed at each 1/4 pitch in the XY direction of the first metal layer (Ag) , 0.15, 0) and YZ (0.15, 0, 0) monitors show the wavelength characteristics of the electric field intensity. Further, FIG. 18 shows a distribution diagram of the electric field intensity in the vicinity of each peak. Referring to FIG. 18, the peak near 650 nm seen in the reflectance and the wavelength characteristic of SQRT in FIG. 17 is PSP existing on the top surface of the first metal layer (Ag thin film), which is 780 nm
It was found that the peak around ̃800 nm was PSP present on the lower surface of the first metal layer (Ag thin film).

  Next, the peak wavelength and the gap (the distance between the first metal layer and the second metal layer) G dependency of the reflectance of the X600Y600 model (633 nm excitation model) were examined using silver and gold as materials. FIG. 19 is a graph showing the peak wavelength and the gap G dependency of the reflectance of the X600Y600 model.

  The position of the top of the second metal layer is the position where the target substance is most likely to be in contact, so that the peak (absorption) on the shortest wavelength side in FIG. It turns out that it is important to increase the overall degree of enhancement. Therefore, in FIG. 19, the peak on the shortest wavelength side is focused.

  Also, as can be seen from FIG. 19, it is expected that the reflectance is large (the degree of enhancement is small) when the gap G is smaller than 20 nm. Furthermore, if the gap G is smaller than 20 nm, the first metal layer and the second metal layer may approach to each other, which may make it difficult to manufacture the device. Therefore, based on G = 20 nm (20 G), Also, determine G that provides good reflectance (good enhancement).

  In the 633 nm excitation model (X600Y600 model), it was found that lower reflectance (higher enhancement) was obtained at 20 nm <G ≦ 240 nm for AG and at 20 nm <G ≦ 220 nm for AU than G = 20 nm. Further, it is understood from this result that the tendency of the wavelength characteristic of reflectance is similar in Ag and Au, and the preferable range of G is not largely different.

  The material is silver, and the G dependency of the reflectivity and the enhancement (the distance between the first metal layer and the second metal layer) of the X780Y780 model (785 nm excitation model) was examined. FIG. 20 is a graph showing the reflectivity G of the X780 Y780 model and the gap G dependency of SQRT.

  For the same reason as FIG. 19, it was found that when G = 20 nm is used as a reference, a lower reflectance (higher enhancement) is obtained at 20 nm <G ≦ 280 nm than in the case of G = 20 nm. This has the same tendency when examined by SQRT, and at the top position of the second metal layer, 20 nm <G ≦ 310 nm, at the bottom position, 20 nm <G ≦ 280 nm and higher than G = 20 nm. It turned out that (SQRT) is obtained.

  From the above, it was found that the upper limit of G is about 280 nm in the 785 nm excitation model, and the upper limit of G is about 220 nm in the 633 nm excitation model. Then, when these upper limit values are normalized with the excitation wavelength, it becomes 220 × 785/633 = 273, and it is found that the upper limit value of the range of G is approximately proportional to the excitation wavelength.

Further, in the present experimental example, assuming that the environment is an air layer or vacuum, n ₁ = 1 but the peripheral dielectric constant such as an aqueous solution is ε ^1/2 and the thickness direction of the first metal layer In consideration of the angle θ formed by the incident light (wavelength λi), it has been found that G has the relationship of the equation (3) already described.

20 [nm] <G. [epsilon] ¹ / 2.cos [theta] <270 [nm]. [Lambda] i / 785 [nm] (3)
This experimental example corresponds to (I-i) and (II-i) described above.

4.2. Experimental Example 2 <Refractive Index of Substrate in Hybrid Model>
In Experimental Example 1, from FIG. 17 and FIG. 18, PSP generated on the upper surface of the first metal layer (Ag thin film) appears on the short wavelength side in two of four or more peaks in the far-field characteristic, It was found that the generated PSP appeared on the long wavelength side.

In Experimental Example 1, PMMA is present as a substrate on the lower surface side of the first metal layer (Ag thin film). The refractive index of PMMA is 1.48. That is, since a thin first metal layer (Ag thin film) of 20 nm easily transmits light, the upper surface side of the first metal layer (Ag thin film) has a peripheral refractive index ε ^1/2 = 1, while Since the lower surface side is different from the peripheral refractive index ε ^1/2 = 1.48, it exhibits two peak characteristics.

  FIG. 21 is a graph of SQRT wavelength characteristics when the substrate of the X780Y780160D20T_AG_80G model is PMMA and when it is air.

Referring to FIG. 21, assuming that the refractive index n = 1 of the substrate is equal to the dielectric constant ε ^1/2 = 1 on the upper surface side of the first metal layer, the wavelength characteristics of PSP generated above and below the first metal layer are It can be seen that the substrates are more aligned than in the case of PMMA. That is, assuming that the refractive index of the substrate is 1, peak wavelengths of PSPs generated above and below the first metal layer are respectively approaching. The value of SQRT was about 40 in the case of the PMMA substrate, but was found to be as large as about 65. This phenomenon is considered to occur because PSPs generated above and below the first metal layer resonate.

  The mesh used in the calculation of FIG. 21 is XY2 nm Z2-10 GG, but when calculated using a mesh of XY1 nm Z1-5 GG at a position of wavelength 780 nm, SQRT has a very large value of 90.2. It was done.

  From the results of this experimental example, for example, when the refractive index of a fluorine-based resin is n = 1.35 and this is used as a substrate, it is in an alcohol (n = 1.329) or an aqueous solution (water n = 1.333) It has been found that substances of the following can be detected and analyzed with very high sensitivity.

  In addition, the present experimental example suggests the tendency of such a phenomenon, and the refractive index n of the substrate and the refractive index (peripheral dielectric constant) of the medium containing the target substance do not necessarily have to coincide with each other. It is considered that the degree of enhancement is improved by matching (approaching) both in the range of ± 10%.

  Therefore, it is understood that when the refractive index of the substrate is n, a high electric field enhancing effect can be obtained if the relationship of the following formula (4) is satisfied.

0.9 · ε ^1/2 ≦ n ≦ 1.1 · ε ^1/2 (4)
[In Formula (4), (epsilon) is a dielectric constant of the periphery of a 1st metal layer, n represents the refractive index of a board | substrate. ]
In addition, although this Example demonstrated about the Hybrid model, this result is effective in the system which PSP generate | occur | produces, It is a phenomenon which holds in above-mentioned (I-ii) and (II-ii).

4.3. Experimental example 3 <one-line wedge model>
In the model of this experimental example, the polarization direction of excitation light and the direction of PSP are the same and behave like a hybrid model, but LSP is generated in the polarization direction of excitation light and PSP is generated in both X and Y directions. Unlike the model, this is a structure in which the enhancement effect is enhanced by the interaction between the LSP generated in the X direction and the polarization direction of the excitation light and the PSP generated by the diffraction grating in the X direction.

FIG. 22 is a graph showing the gap G dependency of the near-field characteristics (SQRT) of the AG and AU X780Y180 model and the X600Y180 model (one-line ‖ model). X780Y180_AG and X780Y180_AU were excited at 785 nm, X600 Y180_AG was excited at 600 nm, and X600 Y180_AU was excited at 620 nm.

  Referring to FIG. 22, it was found that in the case of X780Y180_AG, at 20 nm <G ≦ 260 nm to 280 nm, a higher enhancement (SQRT) is obtained than in the case of G = 20 nm. In addition, in the case of X780Y180_AU, it was found that in 20 nm <G ≦ 300 nm, a higher degree of enhancement (SQRT) is obtained than in the case of G = 20 nm.

  In addition, in X600Y180_AG and X600Y180AU, it was found that at 20 nm <G ≦ 200 nm and 20 nm <G ≦ 180 nm, a higher enhancement (SQRT) is obtained than in the case of G = 20 nm.

  From these facts, it was found that the upper limit of G is approximately proportional to the excitation wavelength according to 180 × 785/633 = 223, as described in Experimental Example 1.

Also in the present experimental example, assuming that the environment is an air layer or vacuum, n ₁ = 1 but the peripheral dielectric constant such as aqueous solution is ε ^1/2 and the thickness direction of the first metal layer In consideration of the angle θ between the incident light (wavelength λi) and G, it has been found that G has the relationship of the equation (7) already described.

20 [nm] <G. [epsilon] ¹ / 2.cos [theta] <= 220 [nm]. [Lambda] i / 785 [nm] (7)
[In the formula (7), ε is the dielectric constant of the periphery of the first metal layer, θ is the irradiation angle of incident light, and the inclination angle from the thickness direction of the first metal layer, λi is the incident light Represents a wavelength [nm]. ]
The present experimental example corresponds to the above (III-i).

4.4. Experimental example 4 <one-line wedge model>
FIGS. 23 and 24 are graphs showing the gap G dependency of the near-field characteristic of the one-line ⊥ model. Fig.23 (a) shows G dependence of SQRT of X180Y600_AG_100D20T @ 640nm model, FIG.23 (b) shows G dependence of SQRT of X180Y600_AU_100D20T @ 640nm model, FIG.24 (b) shows X180Y780_AU_140D20T @ 785nm model Shows the G dependence of SQRT. Further, FIG. 24A shows the G dependency of SQRT of the X180Y780_AG_140D20T @ 785 nm model.

  In the case of the X180Y600 model, the peak (640 nm) on the short wavelength side of both the top and bottom of the second metal layer has a higher enhancement (SQRT) at 20 nm <G ≦ 220 nm to 240 nm for AG than in the case of G = 20 nm. It turned out that it can be obtained. Moreover, in the case of AU, it turned out that a higher degree of enhancement (SQRT) is obtained at 20 nm <G ≦ 240 nm to 270 nm than in the case of G = 20 nm.

  In the case of the X180Y780 model, the peak (640 nm) on the short wavelength side of both the top and bottom of the second metal layer has a higher enhancement (SQRT) at 20 nm <G ≦ 290 nm to 310 nm for AG than at G = 20 nm. It turned out that it can be obtained. In addition, in the case of AU, it was found that at 20 nm <G ≦ 270 nm to 290 nm, a higher degree of enhancement (SQRT) is obtained than in the case of G = 20 nm.

  From these facts, it was found that the upper limit of G is approximately proportional to the excitation wavelength according to 270 × 633/785 = 217, as described in Experimental Example 1.

Also in the present experimental example, assuming that the environment is an air layer or vacuum, n ₁ = 1 but the peripheral dielectric constant such as aqueous solution is ε ^1/2 and the thickness direction of the first metal layer In consideration of the angle θ between the incident light (wavelength λi) and G, it has been found that G has the relationship of the equation (3) already described.

20 [nm] <G. [epsilon] ¹ / 2.cos [theta] <270 [nm]. [Lambda] i / 785 [nm] (3)
[In the formula (3), ε is the dielectric constant of the periphery of the first metal layer, θ is the irradiation angle of incident light, and the inclination angle from the thickness direction of the first metal layer, λi is the incident light Represents a wavelength [nm]. ]
Here, when the PMMA substrate is an air substrate with a refractive index n = 1, the peak of the reflectance spectrum is 1 peak, and in the PMMA substrate, SQRT is 53 at 635 nm, while in the air substrate, 620 nm. SQRT increased with 66 and increased.

  This experimental example corresponds to the above (II-i).

4.5. Experimental example 5 <penetration model and non-penetration model in one-line wedge model and hybrid model>
FIG. 25 shows a schematic view of the penetration model and the non-penetration model. FIG. 26 shows SQRT and PSP = Ez (0,0.15,0) z = 200 nm wavelength characteristics of the penetration model (denoted as “Bump1” in the figure) and the non-penetration model (denoted as “Bump2” in the figure). Show.

  It can be seen from FIG. 26 that although the penetration model and the non-penetration model have almost no difference in the shape of the profile of the wavelength characteristic, the degree of enhancement of the non-penetration model is slightly high. Furthermore, it was also found that the intensity Ez (0,0.15,0) z = 200 nm of PSP in the Y direction is directly proportional to the degree of enhancement of SQRT. This result is different from the Hybrid model and the one-line ‖ model. The one-line ⊥ model is considered to be a mode that utilizes a “confined PSP” in which the PSP is minimized at the central portion of the second metal layer.

  Next, in the Hybrid model, the wavelength characteristics of the through model and the non-through model were compared. FIG. 27 and FIG. 28 are graphs showing the wavelength characteristics of SQRT of the penetration model (Bump1) and the non-penetration model (Bump2). FIG. 27 relates to X600Y600_120D20T_AG_100G, and FIG. 28 relates to X780Y780_160D20T_AG_160G.

  In the X600Y600_120D20T_AG_100G model, the SQRT at 620 nm was larger in the penetration model than in the non-penetration model (Bump1> Bump2), but the FWHM (half bandwidth) was clearly the reverse (Bump1 <Bump2). Moreover, in the X780Y780_160D20T_AG_160G model, the SQRT at 760 nm was smaller in the penetration model than in the non-penetration model (Bump1 <Bump2).

  From these results, it can be concluded that the non-penetration model (Bump 2) has the effect of increasing the peak intensity on the short wavelength side or widening the half width as a result of reducing the peak intensity on the long wavelength side . In the non-penetration model, there is no hole in the first metal layer, and it seems that LSP mirroring is effective.

4.6. Experimental Example 6 <Pitch (P2) Dependence in Y Direction of One-Line PSP / LSP Model According to the Present Invention>
The far-field characteristics were examined for a model in which 80D20T60G of Ag (second metal layer 30) was disposed at a pitch of 120 nm in the X direction and at a pitch of 300 nm, 400 nm, 500 nm, 600 nm, and 700 nm in the Y direction.

  FIG. 29 is a graph showing the wavelength characteristic of reflectance normalized per unit area of each model. The graph shows reflectance characteristics when the pitch in the X direction is 120 nm and the pitch in the Y direction is a variable in the one-line PSP / LSP model according to the present invention. The lower the reflectance, the higher the degree of enhancement.

  Similar to what is disclosed in Non-Patent Document 1 (OPTICS LETTERS, Vol. 34, No. 3, 2009, 244-246), high enhancement at Y = 400 nm pitch to 700 nm pitch near the intersection of PSP and LSP Can be expected. Furthermore, the lowest reflectance was observed at pitches of 500 nm and 600 nm in the Y direction.

  In FIG. 30, the n = 1 PSP dispersion relation of Ag is indicated by a broken line, and the LSP of the Ag model is indicated by a straight line. FIG. 30 shows a dispersion relation in which the wavelength indicating the local minimum value of the reflectance read from the graph of FIG. 29 is plotted for each pitch in the Y direction as the dispersion relation of Ag of peripheral refractive index n = 1. From the dispersion relation of FIG. 30, the LSP peak wavelength was estimated to be 608 nm. A plot close to SPP Ag n = 1 is considered as PSP under Ag film.

Therefore, the excitation wavelength is 608 nm, Ag (second metal layer) having a shape of 80D20T60G is fixed at 120 nm pitch in the X direction, and pitch in the Y direction is changed in 100 nm steps in the range of 200 nm to 900 nm. Near field characteristics and Raman enhancement (Raman EF) were obtained. The results are shown in FIG. FIG. 31 (a) is a plot of SQRT (Ex ² + Ez ² ) when the pitch in the Y direction when the excitation wavelength is 608 nm is gradually increased from the basic model Y = 120 nm. It is. FIG. 31 (b) is a plot of Raman EF when the pitch in the Y direction when the excitation wavelength is 608 nm is gradually increased from the basic model Y = 120 nm.

In the basic structure of X120Y120, the enhancement is SQRT (Ex ² + Ez ² ) = 17.9 at the top end of Ag (the second metal layer 30), whereas when the pitch in the Y direction is extended, the enhancement is linear Of the peak wavelength of the LSP of Ag (the second metal layer 30) and the PSP of the Ag layer (the first metal layer 10). It turns out that it is halved at pitch = 700 nm and then rises gradually. The reason for showing such pitch dependency is that the pitch in the Y direction = 600 nm is the case of m = 1 of the diffraction grating, and the case of m = 2 is the pitch in the Y direction = 1200 nm.

  The reason why the degree of enhancement is larger when the PSP⊥LSP1 line model is P2> 120 nm than when P1 = P2 = 120 nm is that LSP occurs in the deflection direction of the excitation light and PSP occurs in all directions. This is because even when the pitch in the Y direction is shorter than 600 nm, diagonally generated PSPs having a pitch of 600 nm exhibit a hybrid effect with LSP.

  From the above, in the case of P1 = 120 nm in the case of normal incidence, according to FIG. 31 (a), SQRT is obtained at 120 nm <P2 <900 nm, preferably 120 nm <P2 <800 nm, more preferably 200 nm <P2 <700 nm. It turned out to be larger than the basic model. Further, in the case of P1 = 120 nm in the case of normal incidence, it was found from FIG. 31 (b) that Raman EF becomes larger than the basic model at 120 nm <P2 <800 nm, preferably 120 nm <P2 <700 nm. That is, it was found that a high degree of enhancement can be obtained if P1 <P2 ≦ Q + P1.

The above experiment is the case where the incident light is perpendicularly incident on the substrate. Hereinafter, the case where incident light is obliquely incident on the substrate will be described.

As described in the section “1.4.1. Propagation-type plasmons and localized-type plasmons”, the dispersion relation equation of a metal is ε (ω) for a metal and ε for a surrounding dielectric. ,
K _SPP = ω / c [ε · ε (ω) / (ε + ε (ω))] ^1/2 (8)
Given by

On the other hand, the wave number K of the evanescent light passing through the grating pitch Q is
K = n ₁ · (ω / c) · sin θ + m · 2π / Q (m = ± 1, ± 2,,) (9)
Where n ₁ is the refractive index of the periphery on the upper surface side of the first metal layer 10, and if the extinction coefficient is κ, the real part ε ′ and the imaginary part ε ′ ′ of the relative dielectric constant ε at the frequency of light are , ^{_{respectively, ε '= n 1 2 -κ}} 2, given by ε "= 2n ₁ κ, if the periphery of substances transparent, because it is Kappa～0, epsilon is a real number, epsilon = n ₁ ² next , N ₁ = ε ^1/2 .

When the wave number of the dispersion relation of the metal and the wave number of the evanescent wave of the incident wave become equal, a propagation type plasmon is generated. That is, since K _SPP = K, from the equations (8) and (9), (ω / c) · {ε · ε (ω) / (ε + ε (ω))} ^1/2 = ε ^1/2 · (ω / C) · sin θ + 2 mπ / Q (m = ± 1, ± 2,,) (2)
When the second metal layer is arranged such that the pitch Q is satisfied, the propagating plasmon is excited.

Expression (2) is a general expression showing the intersection point of the dispersion relation of the propagation type plasmon of the first metal layer and the evanescent light due to the diffraction grating effect brought about by the second metal layer periodically arranged directly or indirectly. At the time of normal incidence used in the simulation, since θ = 0, the above equation (2) is
(.Omega. / C). {. Epsilon..epsilon. (. Omega.) / (. Epsilon. +. Epsilon. (. Omega.))} ^1/2 = ² m.pi./Q (m =. ± .1,. ± .2,...) (14)
The diffraction grating wave number at which the dispersion relation of the metal layer and the wave number of the evanescent light due to the diffraction grating effect brought about by the second metal layer coincide is m · 2π / Q.

For example, in the case of 30 degrees incidence with m = 1, ε ^1/2 = 1, equation (14) is
K = 0.5 · (ω / c) + 2π / Q (15)
The grating pitch in the case of 30 ° incidence at LSP = 633 nm passing through the intersection with the Ag dispersion relationship is 1 eV / c, and the grating pitch Q may be 1250 nm.

Also, assuming that θ = −30 ° (deg.), Equation (14) gives
K = −0.5 · (ω / c) + 2π / Q (16)
Thus, 2π / Q = 3 eV / c, that is, Q = 418 nm, is required to pass through the intersection point of LSP and the dispersion relation of Ag (n = 1).

  FIG. 32 shows the dispersion relationship for determining the grating pitch with the above-described excitation light of 30 degrees and -30 degrees.

Since both + 30 ° incidence and −30 ° incidence are physically the same, when obliquely incident light with an incidence angle of + 30 ° is used, the dispersion of 633 nm LSP and Ag (ε ^1/2 = 1) If we choose the grating pitch to pass through the intersection point of the relationship, we can see that there are two ways to make the grating pitch Q = 1250 nm, 418 nm.

In conclusion, in the case of oblique incidence, as in the case of normal incidence,
P1 <P2 ≦ Q + P1 (1)
It can be seen that the electric field enhancing element with a greater degree of enhancement is obtained than the basic model if

  The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the invention includes configurations substantially the same as the configurations described in the embodiments (for example, configurations having the same function, method and result, or configurations having the same purpose and effect). The present invention also includes configurations in which nonessential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that can achieve the same effects or the same objects as the configurations described in the embodiments. Further, the present invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 1 ... board | substrate, 10 ... 1st metal layer, 20 ... dielectric material column, 30 ... 2nd metal layer, 31 ... 1st metal row, 32 ... 2nd metal row, 100, 200, 250 ... electric field enhancing element, 300 ... Light source, 400: detector, 1000: analyzer, 2000: electronic device, 2010: arithmetic unit, 2020: storage unit, 2030: display unit

Claims (4)

A substrate, a first metal layer formed on the substrate, a dielectric column formed above the substrate, and a dielectric layer formed on the dielectric column and electrically insulated from the first metal layer A plurality of metal layers are included, and the plurality of second metal layers are arranged side by side at a first pitch P1 in the first direction to form a metal row, and the metal rows are arranged in a second direction intersecting the first direction An electric field enhancing element disposed side by side at the second pitch P2;
A light source for irradiating the electric field enhancing element with incident light of linearly polarized light in the first direction;
A detector for detecting light emitted from the electric field enhancing element;
Equipped with
The arrangement of the second metal layer of the electric field enhancing element satisfies the relationship of the following formula (5),
P1 <P2 ≦ Q + P1 and 120 [nm] ≦ P1 ≦ 180 [nm] and P2 <900 [nm] (5)
[Here, Q represents the pitch of the diffraction grating given by the following formula (2).
(.Omega. / C). {. Epsilon..epsilon. (. Omega.) / (. Epsilon. +. Epsilon. (. Omega.)) ^1/2 = .epsilon.1 ^{/ 2} (.omega. / C) .sin .theta. + 2 m.pi./Q (m = 1,2,2,) ... (2)]
The analyzer whose distance G [nm] between the said 1st metal layer and the said 2nd metal layer satisfy | fills the relationship of following formula (3).
20 [nm] <G. [epsilon] ¹ / 2.cos [theta] <270 [nm]. [Lambda] i / 785 [nm] (3)
[In the above formulas, ω is the angular frequency of the localized plasmon excited in the row of the second metal layer, ε (ω) is the dielectric constant of the metal constituting the first metal layer, ε is The dielectric constant of the medium optically contacting the first metal layer, c is the speed of light in vacuum, θ is the irradiation angle of the incident light, and the inclination angle from the thickness direction of the first metal layer λ i represents the wavelength [nm] of the incident light. ] In claim 1 ,
The detector detects Raman scattered light enhanced by the electric field enhancing element. The analysis device according to claim 1 or 2 , a calculation unit that calculates health care information based on detection information from the detector, a storage unit that stores the health care information, and the health care information. An electronic device comprising a display unit to display. In Claim 3 , said health care information is at least one selected from the group consisting of bacteria, viruses, proteins, nucleic acids, and antigens and antibodies, at least one biological substance, or at least one selected from inorganic molecules and organic molecules. Electronic device containing information on the presence or absence or amount of one compound.