JP2012132886A - Method and device for measuring optical characteristics of dielectric on metal thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for measuring optical characteristics of a dielectric on a metal thin film which can accurately and easily measure optical characteristics of a dielectric on a metal thin film, based on a method for measuring the enhancement degree of an electric field by applying a surface plasmon resonance (SPR) phenomenon.SOLUTION: The method for measuring the optical characteristics of the dielectric on the metal thin film includes: irradiating a metal thin film with first exciting light to generate surface plasmon light on the surface of the metal thin film; irradiating the metal thin film with second exciting light different from the first exciting light to generate second light on the surface of the metal thin film; generating interference fringes formed by the surface plasmon light and the second light; measuring an interference fringe pitch of the interference fringes and a propagation length; and calculating optical characteristics of a dielectric on the metal thin film based on the interference fringe pitch and the propagation length.

Description

  The present invention relates to optical characteristics of a dielectric formed on a metal thin film using surface plasmon light generated on the surface of the metal thin film by irradiating the metal thin film having a dielectric formed on the surface with excitation light. The present invention relates to a method for measuring optical characteristics of a dielectric on a metal thin film and an apparatus for measuring optical characteristics of a dielectric on a metal thin film for measuring a dielectric constant εd.

Conventionally, as a method for measuring optical characteristics of a thin film or the like, for example, a method using an ellipsometer disclosed in Patent Document 1 or Patent Document 2 is known.
FIG. 18 is a schematic diagram for explaining the principle of measuring the optical characteristics of the thin film 102 using the ellipsometer 100.

  The ellipsometer 100 irradiates the thin film 102 with polarized incident light 104 at an incident angle φ. Then, the polarization state of the reflected light 106 is measured by detecting the reflected light 106 reflected by the thin film 102.

  Then, a phase difference Δ and a reflection amplitude ratio angle ψ are obtained as changes in polarization of the incident light 104 and the reflected light 106. The phase difference Δ and the reflection amplitude ratio angle ψ (usually expressed as (ψ, Δ). Hereinafter, also described as (ψ, Δ) in this specification) are the wavelength λ of the incident light 104 and the incident angle. It depends on the angle φ, the film thickness d of the thin film 102, and the optical characteristics of the thin film 102.

  As the optical characteristics of the thin film, there are a complex refractive index expressed by Formula 1 and a complex dielectric function expressed by Formula 2.

In this way, (ψ, Δ) obtained by measurement is compared with (ψ _M , Δ _M ) theoretically obtained from a thin film model so that the difference is minimized, for example, at least two The optical characteristics of the thin film 102 can be obtained by adjusting the parameters of the thin film model using multiplication or the like.

  On the other hand, as a specimen detection apparatus for detecting extremely minute substances, electrons and light resonate in a fine region such as a nanometer level, thereby obtaining a high light output (surface plasmon resonance (SPR: 2. Description of the Related Art A surface plasmon resonance device (hereinafter referred to as “SPR device”) applying Surface Plasmon Resonance is known.

  In addition, based on the principle of surface plasmon excitation enhanced fluorescence spectroscopy (SPFS) using surface plasmon resonance (SPR) phenomenon, it is possible to detect a substance with higher accuracy than an SPR device. The surface plasmon enhanced fluorescence spectrometer (hereinafter referred to as “SPFS device”) is also well known.

  In this surface plasmon excitation enhanced fluorescence spectroscopy (SPFS), the surface plasmon light is applied to the surface of the metal thin film under the condition that excitation light such as laser light irradiated from a light source is attenuated by total reflection (ATR) on the surface of the metal thin film. By generating (dense wave), the photon amount of excitation light irradiated from the light source is increased to several tens to several hundred times, and the electric field enhancement effect of surface plasmon light is obtained.

  This electric field enhancement effect efficiently excites the fluorescent substance bound (labeled) with the analyte trapped in the vicinity of the metal thin film in the vicinity of the metal thin film, and observes this fluorescence, thereby allowing an extremely low concentration of the analyte to be analyzed. This is a method for detecting light.

  By the way, to know the absolute value of the electric field enhancement intensity, which is an index of the electric field enhancement effect of such surface plasmon light, for example, in clinical tests such as blood tests using surface plasmon excitation enhanced fluorescence spectroscopy (SPFS). In such a field where high-precision detection is required, it is important to improve the measurement accuracy of analyte detection by correcting detection data using the absolute value of the electric field enhancement intensity.

However, since this enhanced electric field is non-propagating light, direct observation is impossible, and visualization of the electric field enhancement has been conventionally studied.
For example, in Non-Patent Document 1 ("Surface plasmons at single nanoholes in Au films", Yin et al., Appl. Phys. Lett., Vol. 85, No. 3, 19 July 2004, pp. 468-469), Attempts have been made to measure electric field enhancement by observing interference fringes caused by interference between plasmon light and excitation light generated by incident excitation light using a near-field probe.

  That is, in the method of Non-Patent Document 1, as shown in FIG. 19, a metal thin film (gold film) 202 is formed on the upper surface of the dielectric 200, and a pinhole 204 is formed in the central portion. Then, the excitation light 206 is applied to the metal thin film (gold film) 202 formed on the upper surface of the dielectric 200 through the dielectric 200 from directly below the dielectric 200.

  Then, an interference fringe due to interference between the plasmon light 201 and the excitation light 206 generated at the edge portion 204 a of the pinhole 204 by the incident excitation light 206 is observed by the near-field probe 210 arranged immediately above the pinhole 204. is doing.

  As a result, as shown in FIG. 20, concentric interference fringes are observed, whereby the electric field enhancement is measured (estimated).

Japanese Patent Laid-Open No. 10-038694 JP 2001-296182 A

"Surface plasmons at single nanoholes in Au films", Yin et al., Appl. Phys. Lett., Vol. 85, No. 3, 19 July 2004, pp. 468-469 `` Local excitation of surface plasmon polaritons at discontinuities of a metal film: Theoretical analysis and optical near-field measurements '', L Salomon et al., PHYSICAL REVIEW B. vol. B, 125409

  By the way, the interference fringe pitch (interference fringe spacing) of the interference fringes as described above does not depend only on the optical characteristics of the metal thin film (gold film) 202, but is present on the metal thin film, for example, air, water, etc. It is also affected by the optical properties of the medium on the metal thin film such as phosphor.

That is, if the optical characteristics of the metal thin film are known, the optical characteristics of the medium existing on the metal thin film can be measured.
On the other hand, in the method using the above-described ellipsometer, there are a large number of parameters that need to be set, such as a change in incident angle, a change in polarization, and a thin film model, so that the analysis becomes complicated and the time required for measurement becomes great. Furthermore, since the cost of the apparatus is increased, the optical characteristics of the thin film cannot be easily measured.

  Further, in the method of measuring the electric field enhancement disclosed in Non-Patent Document 1, as shown in FIG. 19, the incident angle is changed from obliquely below the dielectric 200, and the dielectric is passed through the dielectric 200. When the thin metal film (gold film) 202 formed on the upper surface of 200 is irradiated with the excitation light 208, for example, as shown in FIG. 21, the interference fringes are not concentric. It may be difficult to measure (estimate) the electric field enhancement.

  In the method of measuring the electric field enhancement in Non-Patent Document 1, since the interference fringes are caused by the interference between the plasmon light 201 generated at the edge portion 204a of the pinhole 204 and the excitation light 206, the metal thin film (true) to be measured ( The electric field enhancement on the plane (plane direction) of the (gold film) 202 cannot be measured.

Further, since the electric field enhancement varies depending on the shape of the edge portion 204a of the pinhole 204, it is practically difficult to measure the absolute value of the electric field enhancement.
In addition, the pinhole 204 must be provided in the metal thin film (gold film) 202. For example, when used as a measurement member such as a microchip, the manufacturing process becomes complicated and the cost increases.

  In the present invention, a method for measuring optical characteristics of a dielectric on a metal thin film, and a dielectric on a metal thin film, which can accurately and easily measure the optical characteristics of the dielectric formed on the metal thin film, in particular, the dielectric constant of the dielectric. An object of the present invention is to provide an optical property measuring apparatus.

  Furthermore, unlike conventional methods, it is not necessary to provide pinholes or edges in the thin film, and it is possible to measure the electric field enhancement on the plane (plane direction) of the thin film to be truly measured. Based on this measured electric field enhancement An object of the present invention is to provide an optical property measuring method for a dielectric on a metal thin film and an optical property measuring apparatus for the dielectric on a metal thin film, which can accurately and easily measure the optical properties of the metal thin film.

The present invention was invented in order to achieve the above-described problems and objects in the prior art, and the method for measuring the optical properties of a dielectric on a metal thin film according to the present invention includes:
Irradiating the first excitation light toward the metal thin film through a dielectric member disposed below the metal thin film, generating surface plasmon light on the surface of the metal thin film,
Irradiating a second excitation light different from the first excitation light toward the metal thin film to generate a second light on the metal thin film surface,
Generating interference fringes by the surface plasmon light and the second light;
Measuring the interference fringe pitch and propagation length of the interference fringes;
The optical characteristic of the dielectric on the metal thin film is calculated based on the interference fringe pitch and the propagation length.

Moreover, the optical property measuring method of the dielectric on the metal thin film of the present invention is
A first excitation light is irradiated toward the metal thin film through a dielectric member disposed below the metal thin film to generate surface plasmon light on the surface of the metal thin film, and the propagation length of the surface plasmon light Measure and
Irradiating the first excitation light toward the metal thin film through the dielectric member, the surface plasmon light is generated on the surface of the metal thin film, and the first thin film is directed toward the metal thin film. Irradiating a second excitation light different from the excitation light to generate a second light on the surface of the metal thin film to generate an interference fringe due to the surface plasmon light and the second light, and the interference Measure the fringe pitch of the fringes,
The optical characteristic of the dielectric on the metal thin film is calculated based on the interference fringe pitch and the propagation length.

In addition, the optical property measuring apparatus of the dielectric on a metal thin film of the present invention is
Generation of first excitation light that generates surface plasmon light on the surface of the metal thin film by irradiating the metal thin film with first excitation light from a light source through a dielectric member disposed below the metal thin film. Equipment,
A second excitation light generator for generating second light on the surface of the metal thin film by irradiating the metal thin film with a second excitation light different from the first excitation light;
When an interference fringe is generated by the surface plasmon light and the second light, an interference fringe pitch and a propagation length are measured, and based on the interference fringe pitch and the propagation length, an optical of the dielectric on the metal thin film is measured. And an optical characteristic measuring device for calculating the characteristic.

In addition, the optical property measuring apparatus of the dielectric on a metal thin film of the present invention is
Generation of first excitation light that generates surface plasmon light on the surface of the metal thin film by irradiating the metal thin film with first excitation light from a light source through a dielectric member disposed below the metal thin film. Equipment,
A second excitation light generator for generating second light on the surface of the metal thin film by irradiating the metal thin film with a second excitation light different from the first excitation light;
When the surface plasmon light is generated, the propagation length of the surface plasmon light is measured, and when an interference fringe is generated by the surface plasmon light and the second light, an interference fringe pitch of the interference fringe is set. And an optical characteristic calculation device that measures and calculates the optical characteristic of the dielectric on the metal thin film based on the interference fringe pitch and the propagation length.

Further, in the present invention, the interference fringe pitch λ _beat and the propagation length δ are expressed by the following equation:

The dielectric constant εd of the dielectric on the metal thin film, which is an optical characteristic of the dielectric on the metal thin film, is calculated by calculating based on the above.

  With this configuration, the lower excitation light, which is the first excitation light, is irradiated from the light source toward the metal thin film formed on the dielectric member through the dielectric member, and the surface of the metal thin film is irradiated. The surface plasmon light is generated, and the second excitation light different from the first excitation light, for example, the upper excitation light is directly irradiated from the outside toward the metal thin film formed on the upper surface of the dielectric member. Thus, propagating light can be generated on the surface of the metal thin film.

Then, interference fringes of interference light are generated due to the difference in the wave number component between the surface plasmon light and the second light in the direction parallel to the plane of the metal thin film, which is the direction in which the surface plasmon light travels.
At this time, by measuring the interference fringe pitch and the propagation length when the contrast of the interference fringe is maximized while changing the amount of the second excitation light, for example, the upper excitation light, the dielectric on the metal thin film is measured. Optical characteristics (dielectric constant εd of dielectric on metal thin film) can be measured (estimated).

  Therefore, it is not necessary to provide pinholes or edges in the metal thin film as in the prior art, and the electric field enhancement on the plane (plane direction) of the metal thin film to be measured can be measured. By simply measuring the interference fringe pitch and propagation length, the optical characteristics of the dielectric on the metal thin film (dielectric constant εd of the dielectric on the metal thin film) can be measured (estimated).

  In the present invention, the second excitation light is an excitation light that is emitted toward the metal thin film through the dielectric member and generates the second light on the surface of the metal thin film. Features.

  Further, in the present invention, the second excitation light is irradiated directly from the upper side of the metal thin film without passing through the dielectric member to generate the second light on the surface of the metal thin film. It is characterized by being.

Further, the present invention is characterized in that the second excitation light is excitation light dispersed from the same light source as the first excitation light.
By configuring in this way, for example, it is only necessary to provide a spectroscopic means such as a half mirror, so that the apparatus can be made compact.

  In addition, for example, the upper excitation light that is the second excitation light is split from the same light source as the lower excitation light that is the first excitation light, so that the upper excitation with exactly the same phase as the lower excitation light. Light can be directly irradiated toward the metal thin film formed on the upper surface of the dielectric member, and accurate optical characteristics (dielectric constant εd of the dielectric on the metal thin film) can be measured (estimated).

In the present invention, the second excitation light is excitation light derived from a light source different from the light source of the first excitation light.
By configuring in this way, for example, the upper excitation light that is the second excitation light is the upper excitation light derived from a light source different from the light source of the lower excitation light that is the first excitation light. By measuring the interference fringe pitch and propagation length when the interference fringe contrast is maximized, the optical characteristics of the dielectric on the metal thin film (on the metal thin film) can be easily changed. The dielectric constant εd) of the dielectric can be measured (estimated).

Further, the present invention is characterized in that the first excitation light is shaped into a predetermined beam shape before entering the dielectric member.
With this configuration, the first excitation light can be shaped into a shape having a steep beam profile such as a rectangular ray or a focused ray, and the measurement accuracy of the propagation length can be improved.

In the present invention, an electric field enhancement member is disposed in the dielectric on the metal thin film,
The interference fringe pitch of the interference fringes appearing on the electric field enhancement measurement member excited by the interference light between the surface plasmon light and the second light, or the interference fringe pitch. And measuring the propagation length.

In the present invention, the electric field enhancement measuring member is a fluorescent material.
In the present invention, the electric field enhancement measuring member is a light scattering material.

  With this configuration, the fluorescent material or the light scattering material is excited by the interference light between the surface plasmon light and the second light, and interference fringes are generated as the fluorescence or the scattered light. For example, a CCD (Charge Coupled Device) Interference fringes can be measured by photodetection means using elements such as CMOS (Complementary Metal Oxide Semiconductor).

In the present invention, the interference light between the surface plasmon light and the second light is detected using a near-field probe,
The interference fringe pitch of the interference fringes detected by the near-field probe, or the interference fringe pitch and the propagation length are measured.

  By configuring in this way, for example, by attaching a fluorescent substance to the tip of the near-field probe and changing the height position of the near-field probe, the fluorescent substance can be excited at a predetermined height position, Thereby, the enhanced fluorescence can be detected by the near-field probe, and the interference fringe pitch and the propagation length of the interference fringes of the interference light detected as the fluorescence can be measured.

  In the present invention, the measurement of the interference fringe pitch, or the measurement of the interference fringe pitch and the propagation length is performed when the contrast of the interference fringe becomes maximum while changing the light amount of the second excitation light. It is characterized by doing.

By configuring in this way, the measurement accuracy of the interference fringe pitch and the propagation length can be improved.
In the method for measuring optical properties of a dielectric on a metal thin film according to the present invention, a member for measuring electric field enhancement having known optical properties is formed on the metal thin film.
Irradiating the first excitation light toward the metal thin film through a dielectric member disposed below the metal thin film, generating the surface plasmon light on the surface of the metal thin film,
Irradiating the second excitation light different from the first excitation light toward the metal thin film to generate the second light on the metal thin film surface,
Generating the interference fringes by the surface plasmon light and the second light;
Measuring the interference fringe pitch and the propagation length of the interference fringes;
After calculating the optical properties of the metal thin film based on the interference fringe pitch and the propagation length,
Removing the electric field enhancement measuring member formed on the metal thin film, placing the dielectric on the metal thin film as the member to be measured on the metal thin film, and measuring the optical characteristics of the dielectric on the metal thin film. Features.

  As described above, even when the optical characteristics of the metal thin film are unknown, the electric field enhancement measurement with the known optical characteristics is performed using the apparatus having the same configuration as the optical characteristic measuring apparatus for the dielectric on the metal thin film of the present invention. By forming the member for use on the metal thin film, the optical characteristics (the refractive index n and the extinction coefficient k of the metal thin film) of the metal thin film can be easily measured (estimated).

  For this reason, after measuring the optical characteristics of the metal thin film using the same apparatus, the member for measuring the electric field enhancement on the metal thin film is removed, and the dielectric on the metal thin film as the member to be measured is placed on the metal thin film. Thus, the optical characteristics of the dielectric on the metal thin film can be measured.

  According to the present invention, complicated parameter setting and analysis like an ellipsometer is performed by measuring electric field enhancement based on the principle of surface plasmon resonance (SPR) phenomenon and surface plasmon excitation enhanced fluorescence spectroscopy (SPFS). The dielectric constant εd, which is the optical characteristic of the dielectric on the metal thin film, can be measured (estimated) accurately and easily.

FIG. 1 is a schematic view schematically showing an outline of an optical property measuring apparatus for a dielectric on a metal thin film, for explaining the optical property measuring method for the dielectric on a metal thin film of the present invention. FIG. 2 is a partially enlarged view of FIG. FIG. 3 is a flowchart for explaining the flow of calculating the optical characteristics of the dielectric on the metal thin film. FIG. 4 is a schematic diagram of the fluorescence emission interference pattern detected by the light detection means 42. 5A is a graph showing the relationship between the refractive index n of the metal thin film 14 and the interference film pitch λ _beat , and FIG. 5B shows the relationship between the extinction coefficient k of the metal thin film 14 and the propagation length δ. It is a graph to show. FIG. 6 is a schematic view schematically showing an outline of a metal thin film optical property measuring apparatus for explaining the metal thin film optical property measuring method of the present invention. FIG. 7 is a schematic view schematically showing an outline of a metal thin film optical property measuring apparatus for explaining the metal thin film optical property measuring method of the present invention. FIG. 8 is a schematic view schematically showing an outline of a metal thin film optical property measuring apparatus for explaining the metal thin film optical property measuring method of the present invention. FIG. 9 is a schematic view schematically showing an outline of an optical characteristic measuring apparatus for a metal thin film for explaining a method for measuring the optical characteristic of a metal thin film according to another embodiment of the present invention. FIG. 10 is a partially enlarged view of FIG. FIG. 11 is a flowchart for explaining the flow of calculating the optical characteristics of the metal thin film. FIG. 12 is a schematic view schematically showing an outline of a metal thin film optical property measuring apparatus for explaining a metal thin film optical property measuring method according to another embodiment of the present invention. FIG. 13 is a partially enlarged view of FIG. FIG. 14 is a flowchart for explaining the flow of calculating the optical characteristics of the metal thin film. FIG. 15 is a schematic diagram schematically showing an outline of an optical property measuring apparatus for a dielectric on a metal thin film, for explaining a method for measuring the optical property of the dielectric on a metal thin film according to another embodiment of the present invention. FIG. 16 is a partially enlarged view of FIG. FIG. 17 is a flowchart for explaining the flow of calculating the optical characteristics of the dielectric on the metal thin film. FIG. 18 is a schematic diagram for explaining the principle of measuring the optical characteristics of a metal thin film using a conventional ellipsometer. FIG. 19 is a schematic diagram illustrating a conventional method for measuring electric field enhancement. FIG. 20 is a schematic diagram schematically showing interference fringes observed in the conventional method for measuring electric field enhancement in FIG. FIG. 21 is a schematic view schematically showing interference fringes observed in the conventional method for measuring electric field enhancement in FIG.

  Hereinafter, embodiments (examples) of the present invention will be described in more detail with reference to the drawings.

1. FIG. 1 shows an outline of an apparatus for measuring optical properties of a dielectric on a metal thin film, for explaining a method for measuring optical properties of the dielectric on a metal thin film according to the present invention. FIG. 2 is a partially enlarged view of FIG. 1, and FIG. 3 is a flowchart for explaining the flow of calculating the optical characteristics of the dielectric on the metal thin film.

1-1. Configuration of Optical Property Measuring Device for Dielectric Material on Metal Thin Film In FIG. 1, reference numeral 10 denotes the optical property measuring device for a dielectric material on a metal thin film as a whole.
As shown in FIGS. 1 and 2, the optical property measuring apparatus 10 for a dielectric on a metal thin film includes a dielectric member 12 having a substantially triangular prism shape, and a horizontal upper surface 12 a of the dielectric member 12. A metal thin film 14 having a known optical characteristic (refractive index n and extinction coefficient k or dielectric constant εm) is formed. A dielectric 15 as a measurement target is formed on the upper surface of the metal thin film 14, and a fluorescent material layer 17 is formed in the dielectric 15 as a member for measuring electric field enhancement.

  Further, a light source 20 is arranged on one side surface 12b side of the dielectric member 12, and a part of the light 22 from the light source 20 is transmitted and the remaining light is reflected. For example, a half mirror A spectroscope 24 is provided.

  The lower excitation light 26, which is the first excitation light transmitted through the spectroscope 24, is adjusted so that the amount of light becomes a constant amount via a variable attenuation (ND) filter 28, and then a dielectric member. 12 enters the side surface 12b of the dielectric member 12 from below the outer side of the dielectric member 12, and passes through the dielectric member 12 toward the metal thin film 14 formed on the upper surface 12a of the dielectric member 12. (Angle) is irradiated with α1.

  As shown in the enlarged view of FIG. 2, surface plasmon light (in the direction parallel to the surface 14 a of the metal thin film 14 is generated on the surface 14 a of the metal thin film 14 by the lower excitation light 26 irradiated on the metal thin film 14. (Sparse / dense wave) 30 is generated.

  On the other hand, of the light 22 from the light source 20, the remaining light 32 split by the spectroscope 24 passes through the phase shift plate 36, is reflected by the mirror 37, and passes through the variable dimming (ND) filter 35. Then, irradiation is performed at a predetermined incident angle α2 (an angle less than the critical angle) from the upper outside of the dielectric member 12 toward the surface 14a of the metal thin film 14 formed on the upper surface 12a of the dielectric member 12. ing.

  On the other side 12 c below the dielectric member 12, a light receiving means 40 is provided for receiving the metal thin film reflected light 38 reflected by the metal thin film 14 from the lower excitation light 26.

  Further, above the measuring member 18, as will be described later, in order to detect the contrast of interference fringes due to fluorescence excited by the fluorescent material layer 17, the emission intensity of the fluorescence from the fluorescent material layer 17 is detected, for example, Further, a light detection means 42 using an element such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) is provided.

  The light source 20, the spectroscope 24, and the variable attenuation (ND) filter 28 constitute a lower excitation light generator 46 as a first excitation light generator, and a phase shift plate 36, variable attenuation ( The ND) filter 35 and the mirror 37 constitute an upper excitation light generator 48 as a second excitation light generator.

  Further, the light detection means 42 is connected to an optical characteristic calculation device 50 such as a CPU of a computer, and converts the electric field enhancement at a predetermined height position of the electric field enhancement measuring member as will be described later. The calculation process to be estimated is performed.

  In this case, although it does not specifically limit as excitation light irradiated from the light source 20, A laser beam is preferable and wavelength 200-900 nm, 0.001-1000 mW LD laser, or wavelength 230-800 nm, 0 A semiconductor laser of 0.01 to 100 mW is suitable.

In addition, the dielectric member 12 is not particularly limited, but may be optically transparent, for example, various inorganic materials such as glass and ceramics, natural polymers, synthetic polymers, and the like, which are chemically stable. From the viewpoints of performance, production stability, and optical transparency, those containing silicon dioxide (SiO ₂ ) or titanium dioxide (TiO ₂ ) are preferred.

In this embodiment, the substantially triangular prism-shaped dielectric member 12 is used. However, the shape of the dielectric member 12 can be changed as appropriate, such as a semicircular shape or an elliptical shape.
In addition, although it does not specifically limit as the metal thin film 14, For example, it can be set as gold | metal | money, silver, aluminum, copper, platinum, and the alloy of these metals.

  In particular, with respect to a metal that is stable against oxidation, such as gold, and has a large electric field enhancement due to surface plasmon light (dense wave), as will be described later, the optical characteristics of the dielectric 15 are measured with higher accuracy. be able to.

  In addition, the method for forming the metal thin film 14 is not particularly limited, and examples thereof include a sputtering method, a vapor deposition method (resistance heating vapor deposition method, electron beam vapor deposition method, etc.), electrolytic plating, electroless plating method, and the like. . It is preferable to use a sputtering method or a vapor deposition method because it is easy to adjust the thin film formation conditions.

  Further, the thickness of the metal thin film 14 is not particularly limited, but preferably, gold: 5 to 500 nm, silver: 5 to 500 nm, aluminum: 5 to 500 nm, copper: 5 to 500 nm, platinum: 5 ˜500 nm and their alloys: preferably in the range of 5 to 500 nm.

  From the viewpoint of the electric field enhancement effect, more preferably, gold: 20 to 70 nm, silver: 20 to 70 nm, aluminum: 10 to 50 nm, copper: 20 to 70 nm, platinum: 20 to 70 nm, and alloys thereof: If the metal thin film is in the range of 10 to 70 nm, the dielectric 15 can be measured more accurately.

  If the thickness of the metal thin film 14 is within the above range, surface plasmon light (dense wave) is likely to be generated, and the optical characteristics of the dielectric 15 can be measured with higher accuracy. In addition, as long as the metal thin film 14 has such a thickness, the size (vertical x horizontal) size and shape are not particularly limited.

  On the other hand, the fluorescent material constituting the fluorescent material layer 17 is not particularly limited as long as it is a material that emits fluorescence by irradiating predetermined excitation light or using a field effect to emit light. In the present specification, “fluorescence” includes various types of light emission such as phosphorescence.

A fluorescent material layer 17 is formed in a predetermined thickness in the dielectric 15 on the upper surface of the metal thin film 14 in a state where such a fluorescent material is contained alone or in a base material.
In this case, the method of forming the fluorescent material layer 17 in a predetermined thickness in the dielectric 15 on the upper surface of the metal thin film 14 is not particularly limited. For example, the following method is used. Can do.

  That is, a light-transmitting resin (polyacrylate, polymethacrylate, polystyrene, polyvinyl butyral, etc.) used as the dielectric 15 and a fluorescent dye as a solvent (ketones, aromatics, esters, halogen-containing hydrocarbons, etc.) The phosphor layer 17 can be formed in the dielectric 15 by mixing in the dielectric 15. In addition, said resin also has the advantage that protein etc. cannot adsorb | suck nonspecifically.

  Alternatively, when the dielectric 15 is a dielectric having a hydroxy group (polymer, titanium oxide, silicon dioxide, etc.), a silane coupling agent is reacted with the dielectric, and if necessary, a fluorescent dye such as carboxymethyldextran A thin film containing a fluorescent dye (consisting of a fluorescent dye) by a method in which a fluorescent dye is bound according to a known method such as an amine coupling method or a method in which a fluorescent dye is vapor-deposited on the dielectric 15 Layers can be stacked.

  Alternatively, a dielectric layer 15 is formed by preparing a thin layer (for example, a plate, sheet, or film using resin, gelatin, etc.) with a material in which a fluorescent dye is vapor-deposited or blended in advance, and laminating it. May be.

1-2. Method for Measuring Optical Properties of Dielectric Material on Metal Thin Film FIG. 3 shows a method for measuring the optical properties of dielectric material on a metal thin film using the optical property measuring apparatus 10 for dielectric material on a metal thin film according to the present invention. It demonstrates along the flowchart shown.

  First, the lower excitation light 26, which is the first excitation light irradiated from the light source 20 and transmitted through the spectroscope 24, passes through a variable dimming (ND) filter 28, and the amount of light becomes a constant amount. After being adjusted, the light is incident on the side surface 12 b of the dielectric member 12 from the lower outside of the dielectric member 12. Then, it is irradiated through the dielectric member 12 toward the metal thin film 14 formed on the upper surface 12a of the dielectric member 12 at a predetermined incident angle (resonance angle) α1.

As a result, as shown in the enlarged view of FIG. 2, surface plasmon light (dense wave) 30 is generated on the surface 14 a of the metal thin film 14 in a direction parallel to the surface 14 a of the metal thin film 14.
In this case, the following method can be used to determine the predetermined incident angle (resonance angle) α1.

  That is, when surface plasmon light (dense wave) 30 is generated on the metal thin film 14, the first lower excitation light 26 and the electronic vibration in the metal thin film 14 are coupled to each other, and the signal of the metal thin film reflected light 38. Therefore, it is only necessary to find a point where the signal of the metal thin film reflected light 38 received by the light receiving means 40 changes (decreases the amount of light).

  On the other hand, of the light 22 from the light source 20, the remaining light 32 dispersed by the spectroscope 24 is transmitted through the phase shift plate 36 and then reflected by a mirror 37 disposed at a predetermined angle, thereby being variable dimming ( ND) is irradiated at a predetermined incident angle α2 (an angle less than the critical angle) toward the surface 14a of the metal thin film 14 formed on the upper surface 12a of the dielectric member 12 through the filter 35. .

  That is, the upper excitation light 34 passes through the phase shift plate 36 and the variable dimming (ND) filter 35 to the surface 14a of the metal thin film 14 at a predetermined incident angle α2 as shown in the enlarged view of FIG. It is irradiated as another second excitation light.

In this case, the upper excitation light 34 irradiates the surface 14 a of the metal thin film 14 with the upper excitation light 34 having the same phase as the lower excitation light 26.
Thereby, as shown in the enlarged view of FIG. 2, the propagating light 44 is generated as the second light at the predetermined height position of the electric field enhancement measuring member on the surface 14a of the metal thin film 14. .

In this case, the phase shift plate 36 is adjusted so that the phase of the upper pumping light 34 is the same as the phase of the lower pumping light 26.
Furthermore, by moving the phase shift plate 36 in a direction orthogonal to the optical axis, it is possible to see the change in the brightness of the interference fringes at one measurement point.

  The angle of the predetermined incident angle α2 is not particularly limited as long as it is an angle equal to or smaller than the critical angle at which the propagating light 44 is generated at a predetermined height position of the electric field enhancement measuring member on the surface 14a of the metal thin film 14. It is not a thing.

Then, as shown in the enlarged view of FIG. 2, the propagation light 44 by the upper excitation light 34 and the interference fringes (interference light) by the surface plasmon light (dense wave) 30 are generated.
By the way, since the interference light of such propagation light 44 and surface plasmon light is near-field light, it cannot be directly seen as it is. For this reason, a fluorescent material layer 17 is provided in the dielectric 15 on the metal thin film 14 as a member for measuring electric field enhancement.

  The fluorescent material of the fluorescent material layer 17 in the dielectric 15 is efficiently excited by the interference light by the propagation light 44 and the surface plasmon light (dense wave) 30, and interference fringes can be observed as fluorescence. It becomes like this.

  By using this principle and measuring the interference fringe pitch and propagation length when the contrast of the interference fringe is maximized while changing the amount of the upper excitation light 34, the optical characteristics (dielectric material) of the dielectric 15 on the metal thin film are measured. Is measured (estimated).

  Although it is not essential to estimate the interference fringe pitch and the like while changing the light amount of the upper excitation light 34, the measurement accuracy of the interference fringe pitch and the propagation length is improved when the interference fringe contrast is maximized. Can be preferable.

  Specifically, by changing the amount of the upper excitation light 34 by the variable dimming (ND) filter 35, the emission intensity of the fluorescence by the fluorescent material layer 17 in the dielectric 15 is changed to an element such as a CCD or CMOS. It is detected by the light detection means 42 using

The fluorescence emission interference pattern 49 detected by the light detection means 42 is as shown in the schematic diagram of FIG.
In the schematic diagram of FIG. 4, the height of the fluorescence emission interference pattern 49 indicates the fluorescence emission intensity by the fluorescent material layer 17. A dielectric member 12 (refractive index n2) is disposed below the metal thin film 14, but is omitted from the schematic diagram of FIG.

From the fluorescence emission interference pattern 49 thus detected, the pitch λ _beat and the propagation length δ of the interference fringes are measured.
Here, as shown in FIG. 4, the pitch λ _beat of the interference fringes is the distance from the point A to the point B of the fluorescence emission interference pattern, that is, the bright fringe next to it from the center of the bright fringe among the interference fringes. The distance to the center of

  Further, as shown in FIG. 4, the propagation length δ is such that the emission intensity of the fluorescence emission interference pattern from the end C of the lower excitation light 26 is 1 / e times the maximum value (e is the number of Napier). The distance to D.

  In this embodiment, the propagation length δ is measured using the interference fringes of the interference light as described above, but without irradiating the upper excitation light 34 as the second excitation light, Only the lower excitation light 26 that is the first excitation light is irradiated onto the metal thin film 14 through the dielectric member 12 to generate the surface plasmon light 30 on the surface 14a of the metal thin film 14, and in this state the surface plasmon The propagation length δ of the light 30 can also be measured.

  Also in this case, similarly to the case of the interference light described above, the propagation length δ is 1 / e (e is the number of Napiers) of the emission intensity of the surface plasmon light 30 from the end C of the lower excitation light 26. It can be measured by determining the distance to the point.

  When actually measuring the propagation length δ, the detection accuracy such as the position of the end C of the lower excitation light 26, which is the first excitation light, can be easily detected without being affected by the interference fringe pitch of the interference light. Since the measurement can be performed with high accuracy, it is practically preferable to measure the propagation length δ without generating interference light.

In this way, by measuring the interference fringe pitch λ _beat and the propagation length δ, the real value Kspp ′ and the imaginary value Kspp ″ of the surface plasmon wave number vector are calculated from the following equations 8 and 9. Can do.

Here, Kn1 represents the wave number of the second excitation light (upper excitation light 34) in the dielectric 15 (upper excitation light side medium).

  That is, the surface plasmon wave number vector can be expressed as in Expression 10.

On the other hand, the surface plasmon wave number vector can be approximated as shown in Equation 11.

Here, εd is the dielectric constant of the dielectric 15 (becomes a real value), εm is the dielectric constant of the metal thin film 14 (becomes a complex number), ω is the angular frequency of light, and c is the speed of light in vacuum. .

  From the equations 10 and 11, the dielectric constant εd of the dielectric 15 can be calculated as in the equation 12.

By performing such calculation by the optical property calculation device 50, the optical property of the dielectric 15 on the metal thin film 14 can be measured (estimated) accurately and easily.

1-3. Interference fringe pitch described above lambda _beat and the measuring method of propagation length [delta], as a method of measuring the interference fringes pitch lambda _beat and propagation length [delta], is not particularly limited, it may be used various known methods, as follows By using a simple method, measurement can be performed with higher accuracy.

In this embodiment, when the wavelength λ ₀ of the excitation light 22 is 633 nm, the refractive index n1 of the dielectric 15 is 1.33, and the incident angle α2 of the excitation light is 45 °, the interference fringe pitch λ beat of the fluorescence emission interference pattern. The average value is about 1.28 μm, and the average value of the propagation length δ is 3.2 μm.

At this time, as shown in FIG. 5, when the optical characteristic (dielectric constant εd) of the dielectric 15 is changed, the change of the interference fringe pitch λ _beat is about 0.001 μm, and the change of the propagation length δ is about 0. .1 μm order.

For this reason, while increasing the optical magnification of the light detection means 42 to, for example, 100 to 200 times, and measuring the plurality of interference fringes with the range measured by the light detection means 42 being, for example, 1 mm, the interference fringe pitch. Accumulate the amount of change in λ _beat .

Thus, by setting the measurement range to 1 mm, the amount of change in the interference fringe pitch λ _beat increases to 0.78 μm as shown in Equation 13.

Here, when the optical magnification of the light detection means 42 is increased to 200 times, the amount of change in the interference fringe pitch λ _beat is enlarged to 0.78 μm × 200 = 156 μm and can be detected by the light detection means 42. .

For example, if the light detection means 42 is a CCD camera having a pixel size of 14 μm square, 156 μm corresponds to about 11 pixels, so that sufficient measurement resolution can be obtained and the interference fringe pitch λ _beat can be measured with high accuracy. be able to.

On the other hand, the propagation length δ can be increased by increasing the wavelength λ ₀ of the excitation light 22.
For example, when the wavelength λ ₀ of the excitation light 22 is changed from 633 nm to 780 nm, the average value of the propagation length δ increases from 3.2 μm to 13 μm (actual measurement value).

For this reason, the change of the propagation length δ increases from about 0.1 μm order to about 0.5 μm order.
As described above, when the optical magnification of the light detection means 42 is increased to 200 times, the change amount of the propagation length δ is expanded to 0.5 μm × 200 = 100 μm and can be detected by the light detection means 42. .

  For example, if the light detection means 42 is a CCD camera having a pixel size of 14 μm square, 100 μm corresponds to about 7 pixels, so that sufficient measurement resolution can be obtained and the propagation length δ can be measured with high accuracy. it can.

2. FIG. 6 is a schematic diagram of an optical property measuring apparatus for a dielectric on a metal thin film, for explaining a method for measuring the optical properties of the dielectric on a metal thin film according to the present invention. It is the schematic which shows typically.

  The optical property measuring apparatus 10 for a dielectric on a metal thin film according to this modification has basically the same configuration as the optical characteristic measuring apparatus 10 for a dielectric on a metal thin film shown in FIGS. Since the same is applied to the same component, the same reference numeral is assigned to the same component, and detailed description thereof is omitted.

2-1. Configuration of Optical Property Measuring Device for Dielectric Material on Metal Thin Film In this modification, as shown in FIG. 6, the upper excitation light 34 is irradiated by a light source 52 different from the light source 20 of the lower excitation light 26. is doing. By configuring in this way, the upper excitation light 34 derived from the light source 52 different from the light source 20 of the lower excitation light 26 can be obtained, so that the light amount of the upper excitation light 34 can be easily changed, By performing the same measurement method as in the first embodiment, the optical characteristics of the dielectric 15 can be measured (estimated) with high accuracy and ease.

  Although not shown, the upper excitation light 34 may be irradiated by a light source 52 different from the light source 20 of the lower excitation light 26 also in other embodiments.

3. FIG. 7 is a schematic diagram of an optical property measuring apparatus for a dielectric on a metal thin film, for explaining the optical property measuring method for a dielectric on a metal thin film according to the present invention. It is the schematic which shows typically.

3-1. Configuration of Optical Property Measuring Device for Dielectric Material on Metal Thin Film In this modification, as shown in FIG. 7, the first lower excitation light 26 transmitted through the spectroscope 24 passes through a neutral density (ND) filter 28. After the light quantity is adjusted so as to be a certain amount, the light is incident on the side surface 12b of the dielectric member 12 from the lower outside of the dielectric member 12, and the upper surface of the dielectric member 12 is interposed via the dielectric member 12. The metal thin film 14 formed on 12a is irradiated with a predetermined incident angle (resonance angle) α1.

  On the other hand, of the light 22 from the light source 20, the remaining light 32 split by the spectroscope 24 is reflected by the mirror 37, and passes through a variable attenuation (ND) filter 35 and a phase shift plate 36, and is a dielectric member. The light enters the side surface 12b of the dielectric member 12 from below the outer side of the dielectric member 12, and passes through the dielectric member 12 toward the surface 14a of the metal thin film 14 formed on the upper surface 12a of the dielectric member 12. Irradiation is performed at an angle α2 (an angle less than the critical angle).

  That is, the light incident on the side surface 12 b of the dielectric member 12 from the lower outside of the dielectric member 12 through the variable dimming (ND) filter 35 and the phase shift plate 36 is used as the second lower excitation light 33. The surface 14a of the metal thin film 14 is irradiated at a predetermined incident angle α2.

  As described in the first embodiment, when the two excitation lights 26 and 34 are both incident on the side surface 12b of the dielectric member 12 and irradiated from the lower side of the metal thin film 14 as described above, Interference fringes of interference light can be measured.

  By using the optical property measuring apparatus 10 for a dielectric on a metal thin film having such a configuration, the optical property of the dielectric 15 can be measured (estimated) accurately and easily by performing the same measurement method as in Example 1. can do.

  Although not shown, in the case of other embodiments, the two excitation lights 26 and 34 are both incident on the side surface 12b of the dielectric member 12 and irradiated from below the metal thin film 14. You can also

4). FIG. 8 is a schematic diagram of an optical property measuring apparatus for a dielectric on a metal thin film, for explaining the optical property measuring method for a dielectric on a metal thin film according to the present invention. It is the schematic which shows typically.

  The optical property measuring apparatus 10 for a dielectric on a metal thin film according to this modification has basically the same configuration as the optical characteristic measuring apparatus 10 for a dielectric on a metal thin film shown in FIGS. Since the same is applied to the same component, the same reference numeral is assigned to the same component, and detailed description thereof is omitted.

4-1. Configuration of Optical Property Measuring Device for Dielectric Material on Metal Thin Film In this modification, before the lower excitation light 26 transmitted through the variable dimming (ND) filter 28 enters the side surface 12b of the dielectric member 12, beam shaping is performed. The lower excitation light 26 is configured to be shaped into a predetermined beam shape through the lens 29.

  In this way, by using the beam shaping lens 29, the beam shape is shaped into a predetermined beam shape having a steep beam profile, such as a rectangular beam or a focused beam, thereby improving the measurement accuracy of the propagation length δ. Can do.

  By using the optical property measuring apparatus 10 for a dielectric on a metal thin film having such a configuration, the optical property of the dielectric 15 can be measured (estimated) accurately and easily by performing the same measurement method as in Example 1. can do.

5. Example Using Light Scattering Material as Member for Measuring Electric Field Strength Enhancement FIG. 9 is a diagram of a dielectric on a metal thin film for explaining a method for measuring optical properties of the dielectric on a metal thin film according to another embodiment of the present invention. FIG. 10 is a schematic diagram schematically showing the outline of the optical property measuring apparatus, FIG. 10 is a partially enlarged view of FIG. 9, and FIG. 11 is a flowchart for explaining the flow of calculating the optical property of the dielectric on the metal thin film.

  The optical property measuring apparatus 10 for a dielectric on a metal thin film according to this embodiment has basically the same configuration as the optical characteristic measuring apparatus 10 for a dielectric on a metal thin film shown in FIGS. Since the same is applied to the same component, the same reference numeral is assigned to the same component, and detailed description thereof is omitted.

5-1. Configuration of Optical Property Measuring Device for Dielectric Material on Metal Thin Film In Example 1, the fluorescent material layer 17 was formed as a member for measuring the electric field enhancement in the dielectric 15 on the upper surface of the metal thin film 14, In the embodiment, a light scattering material layer 57 is formed in the dielectric 15 instead of the fluorescent material layer 17 as a member for measuring electric field enhancement.

Then, the light scattering material of the light scattering material layer 57 is excited, and the scattered light enhanced thereby is detected by the light detection means 42, and the interference fringe pitch λ _beat and propagation when the interference fringe contrast is maximized. It is configured to measure the length δ.

In this case, fine particles such as gold colloid, titanium oxide, silicon, and SiO ₂ (glass) can be used as the light scattering material.

5-2. About the optical characteristic measuring method of the dielectric on a metal thin film About the optical characteristic measuring method of the dielectric on a metal thin film using the optical characteristic measuring apparatus 10 of the dielectric on a metal thin film of the present invention configured as described above, FIG. It demonstrates along the flowchart shown.

  As in the first embodiment, as shown in FIG. 9, first, light 22 is irradiated from the light source 20 toward the metal thin film 14 formed on the upper surface 12 a of the dielectric member 12. Irradiated at an angle (resonance angle) α1, as shown in the enlarged view of FIG. 10, surface plasmon light (dense wave) 30 is formed on the surface 14a of the metal thin film 14 in a direction parallel to the surface 14a of the metal thin film 14. Is generated.

  On the other hand, as shown in FIGS. 9 and 10, the upper excitation light 34 is irradiated onto the surface 14a of the metal thin film 14 at a predetermined incident angle α2 (an angle less than the critical angle), so that the surface 14a of the metal thin film 14 is irradiated. The propagating light 44 is generated at a predetermined height position of the member for measuring the electric field strength at.

  Then, as shown in the enlarged view of FIG. 10, the wave number component in the direction parallel to the surface 14 a of the metal thin film 14, which is the direction in which the surface plasmon light 30 travels, of the propagation light 44 by the upper excitation light 34 and the surface plasmon light 30. Due to the difference, interference fringes of interference light are generated.

  Since this interference fringe is near-field light and cannot be seen directly as it is, in this embodiment, a light scattering material layer 57 is provided in the dielectric 15 on the upper surface of the metal thin film 14 as a member for measuring electric field strength. The light scattering material layer 57 in the dielectric 15 is excited by the formed propagation light 44 by the upper excitation light 34 and interference fringes (interference light) by the surface plasmon light (dense wave) 30 by the lower excitation light 26. Let

Using this principle, the optical characteristics of the dielectric 15 are measured by measuring the interference fringe pitch λ _beat and the propagation length δ when the contrast of the interference fringe is maximized while changing the light amount of the upper excitation light 34 ( Estimated).

In the same manner as in the first embodiment, the optical characteristics of the dielectric 15 (dielectric constant εd of the dielectric 15) can be measured (estimated) from the pitch λ _beat and the propagation length δ of the interference fringes.

6). FIG. 12 is a diagram illustrating a method for measuring the optical characteristics of a dielectric on a metal thin film according to another embodiment of the present invention. FIG. 13 is a partial enlarged view of FIG. 12, and FIG. 14 is a flowchart for explaining the flow of calculating the optical characteristics of the dielectric on the metal thin film.

  The optical property measuring apparatus 10 for a dielectric on a metal thin film according to this embodiment has basically the same configuration as the optical characteristic measuring apparatus 10 for a dielectric on a metal thin film shown in FIGS. Since the same is applied to the same component, the same reference numeral is assigned to the same component, and detailed description thereof is omitted.

6-1. Apparatus Configuration of Optical Property Measuring Device for Dielectric Material on Metal Thin Film In Example 1, a fluorescent material layer 17 is formed as a member for measuring electric field enhancement in dielectric 15 on the upper surface of metal thin film 14, and the fluorescent material layer In this embodiment, the fluorescent material layer 17 is formed in the dielectric 15, although the light emission intensity of the fluorescence from the light is detected by the light detection means 42 using an element such as a CCD or CMOS. However, the near-field probe 54 is used as an electric field enhancement measurer.

  For example, the fluorescent material 55 is attached to the tip of the near-field probe 54 as a member for measuring the electric field intensity, and the fluorescent material is excited at a predetermined height position by changing the height position of the near-field probe 54. This allows enhanced fluorescence to be detected by the near-field probe 54.

For this reason, by using the same principle as in the first embodiment, by measuring the interference fringe pitch λ _beat and the propagation length δ when the interference fringe contrast is maximized, the optical characteristics of the dielectric 15 (dielectric dielectric) The rate εd) is measured (estimated).

6-2. Method for Measuring Optical Properties of Dielectric Material on Metal Thin Film FIG. 14 shows a method for measuring optical properties of dielectric material on a metal thin film using the optical property measuring apparatus 10 for dielectric material on a metal thin film according to the present invention. It demonstrates along the flowchart shown.

  As in the first embodiment, as shown in FIG. 12, first, light 22 is irradiated from the light source 20 toward the metal thin film 14 formed on the upper surface 12 a of the dielectric member 12. Irradiated at an angle (resonance angle) α1, as shown in the enlarged view of FIG. 13, surface plasmon light (dense wave) 30 is formed on the surface 14a of the metal thin film 14 in a direction parallel to the surface 14a of the metal thin film 14. Is generated.

  On the other hand, as shown in FIGS. 12 and 13, the upper excitation light 34 is irradiated onto the surface 14a of the metal thin film 14 at a predetermined incident angle α2 (an angle less than the critical angle), so that the surface 14a of the metal thin film 14 is irradiated. The propagating light 44 is generated at a predetermined height position in FIG.

  And as shown in the enlarged view of FIG. 13, the wave number component of the direction parallel to the surface 14a of the metal thin film 14 which is the direction which the surface plasmon light 30 of the propagation light 44 by the upper side excitation light 34 and the surface plasmon light 30 runs. Due to the difference, interference fringes of interference light are generated.

  Since this interference fringe is near-field light and cannot be seen directly, in this embodiment, a fluorescent substance 55 is attached to the tip of the near-field probe 54 to bring the near-field probe 54 to a predetermined height position. By approaching, the fluorescent material 55 attached to the tip of the near-field probe 54 by the propagation light 44 by the upper excitation light 34 and the interference fringes (interference light) by the surface plasmon light (dense wave) 30 by the lower excitation light 26. Is excited.

Using this principle, the optical characteristics of the dielectric 15 are measured by measuring the pitch λ _beat and the propagation length δ of the interference fringe when the contrast of the interference fringe is maximized while changing the amount of the upper excitation light 34. (Estimate).

In the same manner as in the first embodiment, the optical characteristics (dielectric constant εd of the dielectric) of the dielectric 15 can be measured (estimated) from the pitch λ _beat and the propagation length δ of the interference fringes.

7). FIG. 15 is a diagram illustrating an optical characteristic measuring apparatus for a dielectric on a metal thin film, for explaining a method for measuring the optical characteristics of the dielectric on a metal thin film according to another embodiment of the present invention. FIG. 16 is a partially enlarged view of FIG. 15, and FIG. 17 is a flowchart for explaining the flow of calculating the optical characteristics of the dielectric on the metal thin film.

  The optical property measuring apparatus 10 for a dielectric on a metal thin film according to this embodiment has basically the same configuration as the optical characteristic measuring apparatus 10 for a dielectric on a metal thin film shown in FIGS. Since the same is applied to the same component, the same reference numeral is assigned to the same component, and detailed description thereof is omitted.

  In Example 1, the optical characteristics of the metal thin film 14 (the refractive index n and the extinction coefficient k of the metal thin film) are known. In this example, the present invention is used when the optical characteristics of the metal thin film 14 are unknown. After measuring (estimating) the optical characteristics of the metal thin film 14 using the optical characteristic measuring apparatus for dielectric on metal thin film, the optical characteristics of the dielectric 15 formed on the upper surface of the metal thin film 14 are measured (estimated).

7-1. Apparatus Configuration of Optical Property Measuring Apparatus for Dielectric on Metal Thin Film In this embodiment, an apparatus having the same configuration as that of the optical characteristic measuring apparatus 10 for dielectric on a metal thin film according to the first embodiment can be used.

  In this embodiment, first, in order to measure the optical characteristics of the metal thin film 14, a fluorescent material layer 16 having a known optical characteristic is formed on the upper surface of the metal thin film 14 as a member for measuring the electric field enhancement. .

Then, using the same principle as in Example 1, the interference fringe pitch λ _beat and the propagation length δ when the interference fringe contrast is maximized are measured to determine the optical characteristics of the metal thin film 14 (the refractive index of the metal thin film). n and extinction coefficient k) are measured (estimated).

7-2. About the optical characteristic measuring method of the dielectric on a metal thin film About the optical characteristic measuring method of the dielectric on a metal thin film using the optical characteristic measuring apparatus 10 of the dielectric on a metal thin film of the present invention configured as described above, FIG. It demonstrates along the flowchart shown.

  As in the first embodiment, as shown in FIG. 15, first, light 22 is irradiated from the light source 20 toward the metal thin film 14 formed on the upper surface 12 a of the dielectric member 12. Irradiated at an angle (resonance angle) α1, as shown in the enlarged view of FIG. 16, surface plasmon light (dense wave) 30 is formed on the surface 14a of the metal thin film 14 in a direction parallel to the surface 14a of the metal thin film 14. Is generated.

  On the other hand, as shown in FIGS. 15 and 16, the upper excitation light 34 is irradiated onto the surface 14a of the metal thin film 14 at a predetermined incident angle α2 (an angle less than the critical angle), so that the surface 14a of the metal thin film 14 is irradiated. The propagating light 44 is generated at a predetermined height position in FIG.

  Then, as shown in the enlarged view of FIG. 16, the wave number component in the direction parallel to the surface 14 a of the metal thin film 14, which is the direction in which the surface plasmon light 30 travels, of the propagating light 44 by the upper excitation light 34 and the surface plasmon light 30. Due to the difference, interference fringes of interference light are generated.

Since this interference fringe is near-field light and cannot be directly seen as it is, a fluorescent material layer 16 having a known optical characteristic is provided on the metal thin film 14 as a member for measuring the electric field intensity.
The fluorescent material of the fluorescent material layer 16 on the metal thin film 14 is efficiently excited by the interference light caused by the propagating light 44 and the surface plasmon light (dense wave) 30, and interference fringes can be observed as fluorescence. It becomes like this.

Using this principle, the optical characteristic (metal) of the metal thin film 14 is measured by measuring the pitch λ _beat and the propagation length δ of the interference fringe when the contrast of the interference fringe becomes maximum while changing the light amount of the upper excitation light 34. The refractive index n and extinction coefficient k) of the thin film are measured (estimated).

  Specifically, by measuring the interference fringe pitch λbeat and the propagation length δ in the same manner as in the first embodiment, the real values Kspp ′ and imaginary values of the surface plasmon wave number vector are obtained from the relational expressions of the above equations 8 and 9. The numerical value Kspp '' can be calculated.

  The surface plasmon wave number vector can be approximated as shown in Equation 14.

Here, εD is a dielectric constant (actual value) of the upper excitation light side medium (phosphor layer) as a medium on the metal thin film, εm is a dielectric constant (complex number) of the metal thin film 14, and ω is an angle of light. The frequency, c, represents the speed of light in vacuum.

  From Expression 14, the relational expression of Expression 15 is obtained.

Then, the refractive index n and the extinction coefficient k, which are the optical characteristics of the metal thin film 14, can be calculated from the relational expression (15).

By performing such calculation by the optical property measuring device 50, the optical property of the metal thin film 14 can be measured (estimated) accurately and easily.

  In the above, the “medium on the metal thin film” is a medium on the metal thin film in which surface plasmon light and propagating light are generated. As described above, the fluorescent material layer is formed on the metal thin film as the upper excitation light side medium. When formed, the fluorescent material layer corresponds to the case where the fluorescent material layer or the like is not formed on the metal thin film which is a region where surface plasmon light and propagation light are generated (for example, in Example 6). For example, air or water corresponds to the medium on the metal thin film.

  In this way, after the optical characteristics of the metal thin film 14 can be measured, the phosphor layer 16 whose optical characteristics are already known on the metal thin film 14 is removed, and the dielectric 15 whose optical characteristics are actually to be measured is placed on the metal thin film 14. To place.

In this state (ie, the same state as in FIG. 1), the optical characteristics (dielectric constant εd of the dielectric) of the dielectric 15 are measured (estimated) from the interference fringe pitch λ _beat and the propagation length δ in the same manner as in the first embodiment. )can do.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to this. For example, in this embodiment, a fluorescent material or a light scattering material is used as a member for measuring electric field enhancement. Although the interference fringes are detected by the light detection means and the near-field probe, any interference fringes can be detected and the interference fringe pitch and propagation length can be measured. Various changes can be made within the range.

  The present invention, for example, accurately determines the dielectric constant εd of a dielectric such as a phosphor disposed on the upper surface of a metal thin film such as a gold film or a silver film without performing complicated parameter setting and analysis as in an ellipsometer. And it can be measured (estimated) easily.

DESCRIPTION OF SYMBOLS 10 Optical characteristic measuring apparatus 12 Dielectric member 12a Upper surface 12b Side surface 12c Side surface 14 Metal thin film 14a Surface 15 Metal thin film top dielectric 16 Fluorescent material layer 17 Fluorescent material layer 18 Measuring member 20 Light source 22 Light 24 Spectrometer 26 Lower excitation light 28 Filter 29 Beam shaping lens 30 Surface plasmon light 32 Light 33 Second lower excitation light 34 Upper excitation light 35 Filter 36 Phase shift plate 37 Mirror 38 Metal thin film reflected light 40 Light receiving means 42 Photodetection means 44 Propagating light 46 Lower excitation Light generation device 48 Upper excitation light generation device 49 Fluorescence emission interference pattern 50 Optical characteristic calculation device 52 Light source 54 Near-field probe 55 Fluorescent material 57 Light scattering material layer 100 Ellipsometer 102 Metal thin film 104 Incident light 106 Reflected light 200 Dielectric 201 Plasmon Light 204 Pinhole 204a Edge 206 excitation light 208 the excitation light 210 near field probe

Claims (26)

An optical property measurement method for measuring optical properties of a dielectric on a metal thin film formed on a metal thin film,
Irradiating the first excitation light toward the metal thin film through the dielectric member disposed below the metal thin film, generating surface plasmon light on the surface of the metal thin film,
Irradiating a second excitation light different from the first excitation light toward the metal thin film to generate a second light on the metal thin film surface,
Generating interference fringes by the surface plasmon light and the second light;
Measuring the interference fringe pitch and propagation length of the interference fringes;
An optical property measurement method for a dielectric on a metal thin film, wherein the optical property of the dielectric on the metal thin film is calculated based on the interference fringe pitch and the propagation length. An optical property measurement method for measuring optical properties of a dielectric on a metal thin film formed on a metal thin film,
Propagation of the surface plasmon light is generated by irradiating a first excitation light toward the metal thin film through a dielectric member disposed below the metal thin film to generate surface plasmon light on the surface of the metal thin film. Measure the length
Irradiating the first excitation light toward the metal thin film through the dielectric member, the surface plasmon light is generated on the surface of the metal thin film, and the first thin film is directed toward the metal thin film. Irradiating a second excitation light different from the excitation light to generate a second light on the surface of the metal thin film to generate an interference fringe due to the surface plasmon light and the second light, and the interference Measure the fringe pitch of the fringes,
An optical property measurement method for a dielectric on a metal thin film, wherein the optical property of the dielectric on the metal thin film is calculated based on the interference fringe pitch and the propagation length. The interference fringe pitch λ _beat and the propagation length δ are expressed as follows:
3. The dielectric on the metal thin film according to claim 1, wherein a dielectric constant εd of the dielectric on the metal thin film, which is an optical characteristic of the dielectric on the metal thin film, is calculated based on Optical property measurement method.   The said 2nd excitation light is irradiated toward the said metal thin film through the said dielectric material member, It is excitation light which generates the said 2nd light on the said metal thin film surface, It is characterized by the above-mentioned. 4. A method for measuring optical properties of a dielectric on a metal thin film according to any one of items 1 to 3.   The second excitation light is excitation light that directly irradiates from the upper side of the metal thin film without passing through the dielectric member to generate the second light on the surface of the metal thin film. The method for measuring optical characteristics of a dielectric on a metal thin film according to any one of claims 1 to 3.   6. The optical characteristic of a dielectric on a metal thin film according to claim 1, wherein the second excitation light is excitation light dispersed from the same light source as the first excitation light. Measuring method.   6. The dielectric on a metal thin film according to claim 1, wherein the second excitation light is excitation light derived from a light source different from the light source of the first excitation light. Optical property measurement method.   8. The optical characteristic measurement of a dielectric on a metal thin film according to claim 1, wherein the first excitation light is shaped into a predetermined beam shape before entering the dielectric member. Method. In the dielectric on the metal thin film, an electric field strength measuring member is disposed,
The interference fringe pitch of the interference fringes appearing on the electric field enhancement measurement member excited by the interference light between the surface plasmon light and the second light, or the interference fringe pitch. The method for measuring optical characteristics of a dielectric on a metal thin film according to any one of claims 1 to 8, wherein the propagation length is measured.   The method for measuring optical characteristics of a dielectric on a metal thin film according to claim 9, wherein the member for measuring electric field enhancement is a fluorescent material.   The method for measuring optical characteristics of a dielectric on a metal thin film according to claim 9, wherein the electric field enhancement measuring member is a light scattering material. Detecting interference light between the surface plasmon light and the second light using a near-field probe;
9. The metal thin film according to claim 1, wherein the interference fringe pitch of the interference fringes detected by the near-field probe, or the interference fringe pitch and the propagation length are measured. Method for measuring optical properties of upper dielectric.   The measurement of the interference fringe pitch, or the measurement of the interference fringe pitch and the propagation length is performed when the contrast of the interference fringe becomes maximum while changing the light amount of the second excitation light. The method for measuring optical characteristics of a dielectric on a metal thin film according to any one of claims 1 to 12. In a state where a member for measuring electric field enhancement having known optical properties is formed on the metal thin film,
Irradiating the first excitation light toward the metal thin film through a dielectric member disposed below the metal thin film, generating the surface plasmon light on the surface of the metal thin film,
Irradiating the second excitation light different from the first excitation light toward the metal thin film to generate the second light on the metal thin film surface,
Generating the interference fringes by the surface plasmon light and the second light;
Measuring the interference fringe pitch and the propagation length of the interference fringes;
After calculating the optical properties of the metal thin film based on the interference fringe pitch and the propagation length,
Removing the electric field enhancement measuring member formed on the metal thin film, placing the dielectric on the metal thin film as the member to be measured on the metal thin film, and measuring the optical characteristics of the dielectric on the metal thin film. 14. The method for measuring optical characteristics of a dielectric on a metal thin film according to any one of claims 1 to 13. An optical property measuring apparatus for measuring optical properties of a dielectric on a metal thin film formed on a metal thin film,
First excitation light that irradiates the metal thin film with first excitation light from a light source through a dielectric member disposed below the metal thin film to generate surface plasmon light on the surface of the metal thin film. A generator,
A second excitation light generator for generating second light on the surface of the metal thin film by irradiating the metal thin film with a second excitation light different from the first excitation light;
When an interference fringe is generated by the surface plasmon light and the second light, an interference fringe pitch and a propagation length are measured. Based on the interference fringe pitch and the propagation length, an optical of the dielectric on the metal thin film An optical characteristic measuring device for a dielectric on a metal thin film, comprising: an optical characteristic measuring device for calculating characteristics. An optical property measuring apparatus for measuring optical properties of a dielectric on a metal thin film formed on a metal thin film,
First excitation light that irradiates the metal thin film with first excitation light from a light source through a dielectric member disposed below the metal thin film to generate surface plasmon light on the surface of the metal thin film. A generator,
A second excitation light generator for generating second light on the surface of the metal thin film by irradiating the metal thin film with a second excitation light different from the first excitation light;
When the surface plasmon light is generated, the propagation length of the surface plasmon light is measured, and when an interference fringe is generated by the surface plasmon light and the second light, an interference fringe pitch of the interference fringe is set. An apparatus for measuring optical characteristics of a dielectric on a metal thin film, comprising: an optical characteristic calculator that measures and calculates an optical characteristic of the dielectric on the metal thin film based on the interference fringe pitch and the propagation length. In the optical characteristic calculation device, the interference fringe pitch λ _beat and the propagation length δ are expressed by the following formulas, that is,
The dielectric on a metal thin film according to claim 15 or 16, wherein a dielectric constant εd of the dielectric on the metal thin film, which is an optical characteristic of the dielectric on the metal thin film, is calculated based on Optical property measuring device.   16. The second excitation light is excitation light that is irradiated toward the metal thin film through the dielectric member and generates the second light on the surface of the metal thin film. 18. An apparatus for measuring optical properties of a dielectric on a metal thin film according to any one of items 1 to 17.   The second excitation light is excitation light that directly irradiates from the upper side of the metal thin film without passing through the dielectric member to generate the second light on the surface of the metal thin film. The apparatus for measuring optical characteristics of a dielectric on a metal thin film according to any one of claims 15 to 17. The optical characteristic measurement device further comprises a spectroscope that separates light from a light source,
20. The metal according to claim 15, wherein the second excitation light is excitation light obtained by separating light from the same light source as the first excitation light by the spectrometer. Equipment for measuring optical properties of dielectric on thin film.   20. The dielectric on a metal thin film according to claim 15, wherein the second excitation light is excitation light derived from a light source different from the light source of the first excitation light. Optical property measuring device. The first excitation light generator further includes a beam shaping lens,
The dielectric material on a metal thin film according to any one of claims 15 to 21, wherein the first excitation light is shaped into a beam shape by the beam shaping lens before entering the dielectric member. Optical property measuring device. The optical characteristic calculation device further includes a light detection means,
In the dielectric on the metal thin film, an electric field strength measuring member is disposed,
The electric field enhancement measurement member is excited by interference light between the surface plasmon light and the second light, and interference fringes appearing on the electric field enhancement measurement member are detected by the light detection means,
23. The dielectric on metal thin film according to claim 15, wherein the interference fringe pitch of the interference fringes or the interference fringe pitch and the propagation length are measured in the optical characteristic calculation device. Optical property measuring device.   The apparatus for measuring optical characteristics of a dielectric on a metal thin film according to claim 22, wherein the electric field enhancement measuring member is a fluorescent material.   23. The apparatus for measuring optical characteristics of a dielectric on a metal thin film according to claim 22, wherein the electric field enhancement measuring member is a light scattering material. The optical property calculation device further comprises a near-field probe,
Detecting interference light between the surface plasmon light and the second light using the near-field probe;
The optical characteristic calculation device measures the interference fringe pitch of the interference fringes detected by the near-field probe, or the interference fringe pitch and the propagation length. An apparatus for measuring optical properties of a dielectric on a metal thin film according to any one of the above.