JP4487921B2 - Standard sample for near-field spectroscopic analysis and spatial resolution evaluation method using this standard sample - Google Patents

Description

  The present invention relates to a standard sample suitable for spatial resolution evaluation in near-field spectroscopic analysis and a spatial resolution evaluation method using the standard sample.

  The spectroscopic analysis method using near-field light (evanescent light) can perform spectroscopic analysis (infrared, Raman, and fluorescence) on a very small region of a sample, for example, several hundred nanometers, and surface nanochemistry. The future is expected to provide an effective means for structural analysis. However, at present, the basic characteristics necessary for applying near-field light to actual material analysis are not grasped, and are currently being sought for practical use.

  For example, evaluation of spatial resolution is extremely important for analysis data obtained with a near-field spectrometer. However, a spatial resolution evaluation method in near-field spectroscopic analysis has not been established yet, and each analyst repeats trial and error in the way he / she wishes. In addition, a standard sample is necessary for the evaluation of spatial resolution, and in order to do so, an established concept is required as to what type of standard sample is appropriate. However, no such concept has been established.

  Therefore, development of a standard sample suitable for spatial resolution evaluation in near-field spectroscopic analysis and development of an established method for spatial resolution evaluation using the standard sample are awaited.

  As a prior art of the present application, Patent Document 1 discloses a method of creating a calibration standard for determining the surface roughness, texture, and haze of a semiconductor wafer using an instrument such as a scanning probe microscope. Patent Document 2 discloses a calibration template used for correcting a relative position between a plurality of probes in a scanning probe microscope having multiple probes. Patent Document 3 discloses a standard sample for optical axis adjustment of an X-ray photoelectron spectroscopic analyzer, and this sample emits fluorescence together with a photoelectron image by X-ray irradiation, thereby providing a guide for optical axis adjustment.

  Patent Document 4 discloses a method for analyzing the surface of a semiconductor sample using a scanning probe microscope, and Patent Document 5 discloses a technique for observing the inside of a living body with high accuracy using a microscope using an optical waveguide. However, the techniques disclosed in any of these patent documents only provide a general technical background for a standard sample to be used for optical microscope measurement, and provide an effective solution for near-field spectroscopy analysis. It is not a thing.

JP-A-9-152324 JP 2004-132745 A JP 2000-304713 A JP 2001-237290 A Special table 2003-517638

  Therefore, an object of the present invention is to provide a standard sample suitable for evaluating spatial resolution in near-field spectroscopic analysis, and to provide a method for evaluating spatial resolution using the standard sample.

  In order to solve the above problems, a first standard sample of the present invention includes a base metal layer having a surface made of a highly reflective metal material, and a thickness of 10 μm or less formed on the base metal layer. A resin layer and a metal layer that partially covers the surface of the resin layer so that the boundary between the resin layer is clear.

  In the standard sample having the above configuration, a part of the resin layer is covered with the metal layer, and the boundary between the resin layer and the metal layer is clear. Therefore, when near-field spectroscopic measurement is performed using this standard sample, the information on the resin layer under the metal layer is blocked, while the information from the exposed resin layer portion is remarkably obtained. As a result, when near-field spectroscopic analysis is performed, it is possible to recognize that there is a great change in the information obtained between the exposed portion and the covered portion of the resin layer of the standard sample, and that there is a boundary in that portion. Therefore, the spatial resolution in the near-field spectroscopic analysis can be evaluated by obtaining the size of the portion. In addition, by setting the thickness of the resin layer to 10 μm or less, the light transmitted through the resin layer is reflected on the surface of the base metal layer and is emitted and detected outside the resin layer. And higher spatial resolution can be obtained.

  In the first standard sample, the resin layer includes at least one functional group among C—H, C═O, Si—O, and C—F functional groups.

  By mapping the peak intensity in the near-field spectrum of these functional groups onto the measurement region of the standard sample, a distribution visualization image of the functional group on the sample can be obtained. By detecting the intensity distribution in the direction crossing the boundary between the resin layer and the metal layer that appears on this visualized image, and detecting the distance on the sample where the intensity changes greatly, the spatial resolution in the horizontal direction can be reduced. Can be evaluated.

  In the first standard sample, the metal layer has a thickness of 3 μm or less.

  With this structure, when the probe used for near-field light measurement is scanned on the surface of the standard sample, the probe can sufficiently follow the step formed between the metal layer and the resin layer, thereby obtaining highly accurate measurement data. be able to.

  In the standard sample, the metal layer has an inclination at a boundary portion with the resin layer.

  With this structure, the probe used for near-field light measurement can sufficiently follow the step formed between the metal layer and the resin layer.

  In order to solve the above problems, a second standard sample of the present invention is the first standard sample, wherein the metal layer is formed of a lattice metal mesh.

  This configuration increases the probability of detecting a position suitable for measurement, that is, the boundary between the metal layer and the resin layer, regardless of where the probe is approached on the standard sample. Reduced.

  In the second standard sample, the base metal layer has a plurality of hemispherical holes having the same diameter as the lattice spacing of the lattice metal mesh on the upper surface portion, and the holes are made of a light-transmitting material. Filled.

  With the above configuration, the hemispherical hole produces a lens effect, and the light incident on the resin layer is reflected in the incident direction, so that the amount of detected near-field light is increased and the detection sensitivity is improved.

  In order to solve the above-described problem, the third standard sample of the present invention is the first standard sample according to the second standard sample, wherein the grid metal mesh is relatively slidable in a direction parallel to the resin layer surface. 2 grid metal meshes.

  In this structure, the area between the lattices, that is, the measurement region of the resin layer can be made variable by sliding the first and second lattice metal meshes with each other. Therefore, the identification lower limit of the measurement region size can be evaluated by performing near-field spectroscopic analysis by changing the size of the measurement region in various ways.

  In order to solve the above problems, a fourth standard sample of the present invention includes a base metal layer having a surface made of a highly reflective metal material, and a lattice having a thickness of 10 μm or less formed on the base metal layer. It has a metal mesh and a resin layer filled in a portion surrounded by the lattice of the lattice metal mesh, and the surface of the lattice metal mesh and the surface of the resin layer are flattened to form the same plane. . In this standard sample, metal fine particles may be dispersed in the resin layer.

  In the standard sample having the above structure, since the resin layer is filled in the lattice of the lattice metal mesh, the boundary between the resin layer and the metal layer is clear, and furthermore, there is no lattice wall surface, thereby preventing irregular reflection. Detection sensitivity is improved. Occasionally, there is no step on the surface of the standard sample and it is flat, so the scanning stability by the probe is very good.

  According to the above configuration, since the fine particles are captured in the holes formed on the standard sample surface, the fine particles can be optimally dispersed on the sample surface. Further, by imparting hydrophilic groups to the surface of the pores and the surface of the fine particles, the affinity between the amphiphilic groups works, so that the fine particles can be more stably fixed. By performing near-field spectroscopic analysis using this sample, it is possible to know to what size fine particles can be identified, that is, to evaluate the lower limit of particle size identification.

  In order to solve the above problems, a sixth standard sample of the present invention is the first standard sample, wherein the resin layer includes at least a first resin layer containing a first functional group, and the first standard sample. A structure in which a second resin layer containing a second functional group different from the functional group is laminated.

  When performing near-field spectroscopic analysis using a standard sample having the above structure, the distribution of the first functional group and the second functional group is mapped, and the functional group is detected by detecting which functional group can be identified. It can be understood that the analysis can be performed up to the depth of the resin layer containing. That is, with this standard sample, the spatial resolution in the vertical direction of the sample can be evaluated.

  In order to solve the above-described problem, a first spatial resolution evaluation method of the present invention includes a step of preparing any one of the first to fourth standard samples, and a near field using the prepared standard sample. Performing a spectroscopic measurement; analyzing the measurement result; obtaining a spectral peak intensity distribution based on a predetermined functional group; and detecting a portion where the intensity value greatly changes in the obtained intensity distribution; Evaluating the spatial resolution in the horizontal direction in the near-field spectroscopic analysis based on the width of the detection portion.

  In the intensity distribution, a large intensity change occurs at the boundary between the metal layer and the resin layer of the standard sample. Therefore, by detecting the width of the changed portion, it is possible to evaluate how accurately the boundary portion can be identified. This makes it possible to evaluate the spatial resolution in the horizontal direction in near-field spectral analysis.

  In order to solve the above-described problem, a second spatial resolution evaluation method according to the present invention includes a step of preparing the third standard sample, and relatively comparing the first and second lattice metal meshes in the standard sample. Performing near-field spectroscopic measurement while sliding and changing the lattice area; analyzing the measurement result to obtain a spectral peak intensity distribution based on a predetermined functional group; and based on the obtained intensity distribution And obtaining a lower limit for distinguishing the resin region defined by the lattice.

  In the above method, near-field spectroscopic measurement can be performed on resin regions having different areas. Therefore, it is possible to evaluate the lower limit for identifying the resin region size by determining whether or not the resin region having the area can be identified from the obtained intensity distribution.

  In the above method, by analyzing the result of near-field spectroscopy measurement performed on a standard sample containing microparticles of different sizes, and determining whether or not the size of microparticles can be detected, the microparticles in near-field spectroscopic analysis It becomes possible to evaluate the size identification lower limit.

  In order to solve the above-described problem, the fourth method of the present invention includes a step of preparing the sixth standard sample, a step of performing near-field spectrometry using the prepared standard sample, and the measurement result. And obtaining the intensity distribution of the spectral peak based on the first and second functional groups, and based on the obtained intensity distribution of the first and second functional groups, the multilayer film in the standard sample Determining an identifiable lower limit value.

  In the above method, by detecting which functional group is identifiable, the identifiability of the resin layer containing the functional group can be evaluated. That is, it is possible to evaluate to which layer of the resin layers configured in multiple layers can be identified, that is, the spatial resolution in the depth direction (vertical direction) of the resin layer.

  As described above, the spatial resolution in the near-field spectroscopic analysis can be evaluated by the standard sample of the present invention, and the effect is great in applying the near-field spectroscopic analysis to the actual material.

  FIG. 1 is a diagram showing an application principle of near-field spectral analysis. FIG. 1A shows a case where light specularly reflected from the surface of the sample 1 is detected and analyzed. In the figure, reference numeral 2 denotes a probe having a tip as small as about several hundreds of nanometers. Near-field light 4 is generated by irradiating the tip portion with light 3 such as infrared light. By detecting the light 5 reflected from the sample surface of the near-field light 4 and performing spectral analysis, it is possible to analyze the chemical structure of a fine portion of the sample surface. In this case, the tip diameter D of the probe 2 determines the theoretical spatial resolution of the measuring device.

  In the case of FIG. 1A, specular reflection from the surface of the sample 1 is detected and spectroscopically analyzed. However, in this case, the intensity of light is weak and it is difficult to apply an actual material. Therefore, as shown in FIG. 2B, the metal layer 6 is provided on the back surface of the sample 1, and the light that has entered the sample 1 is collected by reflection by the metal layer 6, so that the reflected light 7 can be actually analyzed. The light intensity that can withstand is obtained. However, it is considered that the spatial resolution D ′ in this case does not coincide with the theoretical spatial resolution D and is lower than the theoretical value.

  Therefore, there is a need for evaluation of real spatial resolution, and a standard sample is necessary for this purpose. In the present invention, as shown below, a standard sample having a structure in which the organic / inorganic boundary is clearly exposed is proposed.

Embodiment 1
FIG. 2 is a diagram showing the structure of a standard sample according to Embodiment 1 of the present invention. This standard sample is characterized by having a single resin-metal interface. 2A is a cross-sectional view of the standard sample 10, FIG. 2B is a plan view thereof, FIG. 2C is a cross-sectional view of a modified example 10 ′ of the standard sample 10, and FIG. It is a figure for doing. In FIG. 2, reference numeral 11 denotes a base metal layer made of a highly reflective metal such as Fe or Al. The base metal layer 11 may be a glass substrate on which a metal such as Au, Pd, Pt, Al, Ag, Cr, or Ta is deposited. A thin resin layer 12 having a thickness of 10 μm or less is made of a resin containing a functional group such as C—H, C═O, C—O, Si—O, or C—F. In particular, a sample containing a C═O group is a highly sensitive sample. The resin layer 12 is coated on the base metal layer 11 by, for example, spin coating.

  By setting the resin layer 12 to a thickness of 10 μm or less, the near-field light incident on the resin layer passes through the resin layer 2 and reaches the base metal layer 11, is reflected by the surface, and is emitted from the sample. As a result, near-field light including information on the surface of the resin layer can be efficiently collected, and detection sensitivity is improved. The resin layer 12 is made of, for example, polyester, polycarbonate, polyacrylate, polydimethylsiloxane, Teflon (trademark), or polyethylene.

  Reference numeral 13 denotes a metal coating layer that partially covers the resin layer 12. The metal coating layer 13 is provided in order to completely exclude resin information from below the coating area. The metal coating layer 13 has a thickness of 0.1 to 3 μm, and is formed by evaporating a metal such as Au, Pd, Pt, Al, or Ag on the resin layer 12. As shown in FIG. 2B, the metal coating layer 13 preferably covers a part of the surface of the sample 10 to clearly form a single resin-metal boundary 14.

  As shown in FIG. 2C, a slope 15 of θ = 30 to 60 degrees may be provided in the metal coating layer 13 at the boundary portion 14 between the metal coating layer 13 and the resin layer 12. This is to prevent the probe for generating near-field light from being caught on the cross section of the layer 13 during surface scanning. As shown in FIG. 2D, the slope 15 can be formed by projecting an end portion of a mask 16 for depositing a metal coating layer on the resin layer 12 in an eave shape.

  As described above, the thickness t1 of the metal coating layer 13 is preferably 0.1 to 3 μm. The lower limit value of the thickness t1 is a thickness that can completely block the information of the resin layer 12 by the near-field light by the metal coating layer 13. That is, it is sufficient that the near-field light is completely blocked by the metal coating layer 13 and does not reach the resin layer.

  A method for determining the thickness t1 required for blocking near-field light for various metals will be described below.

The graph of FIG. 3 shows the relationship between the IR spectrum intensity by the near-field light of the polycarbonate coated with the metal film and the thickness of the metal film. The vertical axis of the graph shows the intensity of the absorption peak (3000 to 2800 cm ⁻¹ ) due to the C—H group in arbitrary units, and the horizontal axis shows the thickness of the coated metal film normalized to the value of Al. . In the near-field IR measurement, Al was used as the base metal, and the probe size was 1000 nm. From this figure, it is understood that the intensity of the C—H group absorption peak is substantially zero when the normalized thickness of the metal film is approximately 120 nm or more. A peak intensity of 0 means that the IR information of the polycarbonate resin covered with the metal film is completely blocked. That is, in the standard sample 10 of FIG. 2, if the normalized thickness of the Al metal coating film 13 is 120 nm or more (practically 100 nm or more), the IR information of the resin layer 12 is blocked. Can do.

The normalized thickness T is
T = actual thickness (t1) × reflectance (R) (1)
On the other hand, the reflectance (R) is
R = Metal SB (single beam) intensity / Al standard SB intensity (2)
Can be calculated as Therefore, when a metal other than Al is used as the metal coating film 13, the minimum value of the actual metal film thickness t1 can be determined according to the above formulas (1) and (2). Note that the relationships shown in the equations (1) and (2) can also be applied to the determination of the metal coating thickness of the near-field probe.

FIG. 4 shows the results of near-field spectroscopic measurement of samples in which metals are deposited on the polycarbonate resin layer with different thicknesses. In FIG. 4A, Pt / Pb is deposited on the resin layer to a thickness of 60 nm. In this near-field spectral spectrum (IR absorption spectrum), various functional group peaks in the resin layer under the metal layer clearly appear. Therefore, the near-field light passes through the metal coating layer and reaches the resin layer. It seems to have brought the information. Therefore, it is considered that the metal layer does not show a sufficient shielding effect. FIG. 4B shows a near-field spectrum when Au is deposited to a thickness of 120 nm on the resin layer. In this spectrum, it can be seen that the functional group peak in the resin layer does not appear, and therefore the Au layer sufficiently exhibits the shielding effect. In FIGS. 4A and 4B, the vertical axis indicates absorbance in arbitrary units, and the horizontal axis indicates wave number (cm ⁻¹ ).

  On the other hand, the upper limit value in the thickness t1 of the metal coating film 13 is determined by the step following ability of the probe when the surface of the standard sample 10 is scanned by the probe. The near-field light splitting device is based on the mechanism of an atomic force microscope, and if the step at the boundary 14 in the standard sample 10 becomes large, the probe cannot follow the step and accurately detect data. In the present embodiment, the thickness t1 of the metal coating film 13 is defined with the step that can be followed by the probe being approximately 3 μm.

  FIG. 5 is a diagram for explaining the level difference followability of the probe, and shows a surface topographic image in an atomic force microscope. 5A is a sample having a step of 1.0 μm, FIG. 5B is a sample having a step of 1.6 μm, and FIG. 5C is a surface topographic image of a sample having a step of 3.3 μm. . In these images, the height shape of the sample can be grasped, and it is considered that the probe sufficiently follows these steps (indicated as Good in the figure).

  On the other hand, (d) in FIG. 5 is a topographic image of the sample surface when the step is 6.2 microns, and (e) is the sample surface when the step is 10.0 μm. From these images, it is considered that the height of the sample cannot be grasped, and therefore the probe does not follow these steps (indicated as “No Good” in the figure). From observation of such a topographic image, it is understood that if the step is within 3.0 μm, the probe can sufficiently follow the step, and in this embodiment, this step is the upper limit of the thickness t1. .

  Next, the film thickness t2 of the resin layer 12 will be considered.

  FIG. 6 is a diagram showing the relationship between the thickness of the resin layer 12 and the S / N sensitivity at a specific absorption peak in the near-field infrared spectrum. Specifically, polytetrafluoroethylene resin (Teflon (trademark)) is used as the resin material, and the S / N sensitivity of the CF group peak in the near-field infrared spectrum is plotted against the thickness of the resin layer. It is a thing. The probe diameter of the used near-field spectroscopic device is 320 nm, and the substrate on the back surface of the resin layer is a mirror-finished Al substrate.

  As shown in FIG. 6, the C—F group peak can be detected with high sensitivity when the thickness of the resin layer is 10 μm or less. Therefore, it is understood that the thickness of the resin layer 12 in FIG. 2 is desirably 10 μm or less. Originally, near-field spectroscopy can be applied to bulk materials regardless of sample thickness, but a sample that can transmit infrared light can perform high-sensitivity measurements because of its high infrared reflection efficiency on the surface of the underlayer. it is conceivable that.

  FIG. 7 shows the results of near-field infrared spectroscopic analysis of the standard sample shown in FIG. As the standard sample, a metal coating layer formed of Al and a resin layer formed of polycarbonate was used. (A) of FIG. 7 maps the C—H group peak intensity in the near-field infrared spectrum on the sample in order to visualize the C—H group distribution on the standard sample. The left side of the boundary A shown in the figure is the resin layer portion, and the right side is the Al metal portion. In the diagram (a), the distribution density of C—H groups is high in the resin layer portion, and the distribution density of C—H groups decreases toward the Al metal portion beyond the boundary A.

  As shown in the figure (a), the distribution density of C—H groups clearly changes greatly in the vicinity of the boundary A, and clearly shows the existence of the boundary A. FIG. 7B is a surface topographic image of the same sample as FIG. Also from this image, the presence of the boundary A between the resin portion and the metal portion is identified.

  FIG. 7C shows the relationship between the position and the absorbance of the C—H group peak along the analysis line B of the C—H group distribution visualized image in FIG. Therefore, the vertical axis of the figure indicates the absorption peak intensity (absorbance) of the CH group in arbitrary units, and the horizontal axis indicates the measurement position. The distance d at which the absorption peak intensity is 1 / e from the value of the resin portion can be evaluated as the spatial resolution. The spatial resolution d of this measurement example is 4.3 μm. As described above, when the standard sample of the present embodiment is used, the spatial resolution in the near-field spectroscopic analysis can be evaluated using the boundary between the resin part (organic material) and the metal part (inorganic material).

FIG. 8 is a diagram for explaining a method for evaluating the spatial resolution when the standard sample having the structure shown in FIG. 2 is used. Figure (a) shows the change in CH group peak intensity at the boundary when the standard sample is viewed from directly above, and Figure (b) shows the change in CH group peak intensity in the cross section of the boundary. The left side from the boundary shows the resin layer 12, and the right side shows the metal layer 13. The resolution d is indicated by a distance d ₀ during which the C—H group peak intensity is 1 / e from the value of the resin part. When the standard sample having the shape shown in (c) of FIG. 2, those from the width d ₁ of the boundary portions minus the distance d ₀ between the C-H group peak intensity is the 1 / e from the value of the resin portion Spatial resolution. That is, d = d ₀ −d ₁ .

Embodiment 2
FIG. 9 is a diagram showing the configuration of a standard sample according to Embodiment 2 of the present invention. The standard sample of this embodiment is characterized in that a plurality of metal-resin boundaries are provided on the sample. 9A is a plan view of the sample 20, and FIG. 9B is a cross-sectional view taken along the line 20A-20A in FIG. In the figure, 21 indicates a base metal layer, 22 indicates a resin layer, and 23 indicates a lattice metal mesh. The lattice metal mesh 23 replaces the metal coating layer 13 of the first embodiment shown in FIG. 2, and therefore the thickness thereof is in the range of 0.1 to 3 μm, like the metal coating layer 13. The lattice spacing of the lattice metal mesh 23 is 50 to 1000 nm.

  In this embodiment, as shown in FIGS. 4A and 4B, a lattice metal mesh 23 is provided on the resin layer 22, and the resin layer 22 is exposed from a plurality of openings of the metal mesh 23. Has a structure. The material and thickness of the lattice metal mesh 23 in place of the base metal layer 21, the resin layer 22, and the metal coating layer are the same as those in the first embodiment. With such a configuration, in the standard sample of the present embodiment, a plurality of portions where the boundary between the organic substance and the inorganic substance clearly appear are formed uniformly on the entire sample surface. Since the spatial resolution evaluation method in the near-field spectroscopic analysis is the same as that in the first embodiment, the description thereof is omitted.

  For observation of near-field light, it is necessary to make the probe approach a pinpoint in a region of several μm size in order to search for a measurement point, and this work involves considerable labor. However, in the standard sample 20 of the present embodiment, since a plurality of measurement points are uniformly formed on the sample surface, it is possible to bring the probe close to the measurement point no matter where the sample surface is approached, The measurement point search effort is greatly reduced.

  10 and 11 show the measurement results and the spatial resolution evaluation results performed using the standard sample of the second embodiment. FIG. 10A is an optical microscope observation image of the standard sample 20 having the structure of the second embodiment. The lattice metal mesh of the standard sample 20 used for the measurement is made of Cu and arranged on a polycarbonate resin. A near-field spectrum was obtained for the portion indicated as the visualization region in the figure, and the C = O group peak intensity was mapped. FIG. 5B is a diagram showing a mapping result, that is, a C = O group distribution visualized image. Furthermore, the topographic image of the standard sample surface was photographed with an atomic force microscope for the same part. The topographic image of the sample surface is shown in FIG. In FIGS. 2B and 2C, the vertical axis represents the distance in the Y-axis direction, and the horizontal axis represents the distance in the X direction in units of μm.

  In the surface topographic image shown in FIG. 10C, the boundary A between the resin portion and the Cu portion (part of the lattice metal mesh) clearly appears. Furthermore, also in the C = O distribution visualization image of FIG. (B), the boundary A of the resin part and the Cu part appears at the same position as in FIG. (C), and the near-field spectroscopic analysis is performed with high sensitivity. It is shown that.

  FIG. 11 is a graph showing the intensity of the C═O absorption peak along the analysis line B of FIG. 10 in order to evaluate the spatial resolution in the measurement shown in FIG. The vertical axis in the figure indicates the absorbance in arbitrary units, and the horizontal axis indicates the position on the analysis line B. The starting point 0 on the horizontal axis is a value temporarily set for the evaluation of resolution.

  By applying the spatial decomposition evaluation method shown in FIGS. 8A and 8B to the measurement result of FIG. 11, the peak intensity of absorbance is 1 / e of the peak intensity of absorbance in the resin layer region. It can be evaluated that the distance of 5.4 μm is the spatial resolution in this measurement.

Embodiment 3
FIG. 12 is a diagram showing the configuration of the standard sample 30 according to the third embodiment of the present invention. The standard sample of the present embodiment is intended to increase the sensitivity of the standard sample of the second embodiment. (A) of a figure shows the cross-section of the standard sample 30, and FIG. (B) is a figure for demonstrating the effect. In FIGS. 1A and 1B, 31 is a base metal layer having a plurality of hemispherical holes 34 in the surface portion, 32 is a resin layer, and 33 is a lattice metal mesh. The spherical hole 34 is provided with a plurality of holes with a diameter of 50 to 1000 nm by femtosecond laser processing or the like on a metal plate serving as a base metal. The hole 34 is filled with a light transmitting crystal material 35 such as KBr, KCl, NaCl, or CaF. Although not shown, metal fine particles may be mixed in the filling material 35. The lattice metal mesh 33 has an opening 36 having substantially the same size as the spherical hole 34 of the base metal layer 31.

  In the present embodiment, the materials and structures (including the layer thickness) of the base metal layer 31, the resin layer 32, and the lattice metal mesh 33 are the same as or similar to those shown in the first and second embodiments. However, the light that has entered the resin layer 32 through the opening portion 36 of the lattice metal mesh and has transmitted therethrough is reflected and collected in the incident direction by the lens effect generated by the spherical hole 34, as shown in FIG. As a result, it is efficiently detected by the near-field spectrometer. Therefore, the resolution evaluation sensitivity is improved. The reflection efficiency is further improved by mixing metal fine particles into the light-transmitting filling material 35.

  In FIG. 12, the base metal layer in the standard sample of the second embodiment is provided with a hemispherical hole, but it may be provided in the base metal layer in the standard sample of the first embodiment or will be described later. You may apply to the base metal layer of other embodiment.

Embodiment 4
FIG. 13 is a diagram illustrating a configuration of the standard sample 40 according to the fourth embodiment of the present invention. FIG. 1A is a cross-sectional view of the standard sample 40, 41 is a base metal layer, 42 is a resin layer, 43 is a first grid metal mesh provided on the resin layer 42, and 44 is a first grid metal mesh. 43 is a second lattice metal mesh provided on 43. The first and second grid metal meshes 43 and 44 each have a thickness of 0.05 μm to 1.5 μm, and the maximum thickness t1 of the both is the grid metal mesh 23 of the second embodiment. , That is, within the thickness t1 of the metal coating layer 13 of the first embodiment. The configuration and materials other than the thickness of the grid metal mesh are the same as those of the grid metal mesh of the second embodiment, and the base metal layer 41 and the resin layer 42 are the same as those of the first or second embodiment.

  In the standard sample of this embodiment, the exposed area of the resin layer 42 can be arbitrarily adjusted by sliding the first and second lattice metal meshes 43 and 44 in the direction of the arrow in FIG. By performing near-field spectroscopic analysis on a standard sample having various openings while changing the openings of the resin layer 42, the lower limit of the identification of the resin region size can be evaluated.

Embodiment 5
FIGS. 14A and 14B are cross-sectional views of a standard sample according to Embodiment 5 of the present invention. The present embodiment is characterized in that a lattice metal mesh 52 is disposed on the base metal layer 51, and an analysis resin such as polycarbonate is embedded in the mesh opening to form the resin layer 53. In the resin layer 53 ′ shown in FIG. 5B, in order to improve detection sensitivity, metal fine particles are dispersed in the resin layer so that light is multiply reflected. The lattice metal mesh 52 in the present embodiment has a thickness t3 of 10 μm or less in order to make the resin layers 53 and 53 ′ have a thickness of 10 μm or less. The lattice width is preferably 10 μm or less, and the mesh hole size is preferably 10 to 50 μm. The metal species of the mesh is preferably Cu, Al, Fe, Ni or the like.

  The lattice metal mesh 52 is formed on the base metal layer 51 by pressing or an adhesive. As shown in FIG. 2B, when the metal fine particles are mixed in the resin layer 53 ', the size is about 1 μmφ, and the metal species are preferably Fe, Au, Pd, Pt, Al, and Ag. After filling the lattice metal mesh 52 with the resin, the entire surface of the sample is polished so that the lattice metal mesh 52 and the resin layers 53 and 53 'form the same plane. As a result, a surface flattened standard sample is obtained, and the scanning performance of the probe is stabilized. The resin layer is preferably made of the same material as in the first to fourth embodiments.

  As described above, unlike the case of the second embodiment, the standard sample of this embodiment does not have the wall surface of the lattice metal mesh 52, so that irregular reflection of light by the wall surface is prevented and the detection accuracy of near-field light is improved. To do. In addition, since there is no step on the surface of the standard sample, the scanning stability of the probe is extremely excellent. Further, in the case where metal fine particles are mixed in the resin layer 53 ', the detection sensitivity is further improved by the multiple reflection of light.

Embodiment 6
The standard sample concerning Embodiment 6 of this invention is shown to (a) and (b) of FIG. The standard sample 60 of this embodiment is provided with a plurality of holes 62 of 100 to 1000 nmφ on the surface of the base metal layer 61 as shown in the sectional view of FIG. It has a structure in which fine particles 63 are dispersed. The material of the polymer fine particles 63 is polystyrene or polymethacrylate, but fine particles such as SiO ₂ may be used. Further, a hydrophilic group may be added to the surface of the hole 62 of the base metal layer 61 and the surface of the polymer particle 63 so that the polymer particle 63 is stably accommodated in the hole 62.

  As shown in the figure (b), when hydrophilic groups 64 and 65 are provided on the surface of the hole 62 and the surface of the polymer fine particle, the polymer fine particle 63 is stably fixed in the hole 62 by the affinity between them. Thereby, the fine particles can be optimally dispersed on the standard sample. The dispersion state of the polymer fine particles on the standard sample can be observed by obtaining a topographic image of the sample surface using an atomic force microscope.

  Therefore, near-field spectroscopic analysis is performed on the same standard sample, mapping is performed on the intensity of a specific, for example, CH group absorption peak, and a CH group distribution visualized image is obtained, so that it is identified as a single fine particle. What is possible and what is not possible can be determined. By comparing this with, for example, an atomic force microscope image, it becomes possible to evaluate the lower limit of particle size identification.

In the above description, identification of polymer fine particles has been described. However, for example, a similar standard sample can be prepared for fine particles of inorganic material such as SiO ₂ fine particles.

  The standard sample 60 shown in FIG. 15 can be formed by the following process. First, a large number of holes 62 having a diameter of 100 to 500 nm are formed on a glass substrate or the like by femtosecond laser processing. Laser processing may be used as it is, or a metal such as Fe or Al is deposited on the processed glass substrate, and then the surface is slightly oxidized. By this oxidation, hydrophilic groups (Al—O—Al, Al—OH) are introduced on the metal surface.

Polymer fine particles having a diameter of 50 to 1000 nm are prepared. The material of the polymer fine particles may be polystyrene, polymethacrylate, or SiO ₂ . A surfactant is applied to the prepared polymer fine particles. As the surfactant, alkylbenzene sulfonates such as R—SO ₃ Na, carboxylic acid metal salts and the like are used. In this way, polymer fine particles having a hydrophilic group formed on the surface thereof are dispersed on the glass substrate having a hydrophilic group introduced on the surface. The polymer fine particles protruding from the holes are removed from the glass substrate using centrifugal force or the like. As a result, a standard sample capable of evaluating a single fine particle itself is formed.

FIG. 16 shows a method for evaluating the spatial resolution when the standard sample according to the present embodiment is used. Figure (a) shows the signal intensity of the absorption peak in the coupling group with a case where size is made near field spectral analysis of the particles d ₀₀ to d _20, the mapping image in that case. A particle of size d ₀ has a low signal intensity and is difficult to identify as a mapping image. Particles of sizes d ₁₀ and d ₂₀ have a large signal intensity and can be identified as mapping images d ₁₀ ′ and d ₂₀ ′. Therefore, in this case it can be evaluated and the particle size d ₁₀ is identifiable lower limit in the near-field spectroscopy analysis.

  FIG. 16B shows an image when the particle 66 is scanned with the probe tip 67 and a change in signal intensity of the spectrum detected at that time. In the signal waveform 68, the vertical axis indicates the S / N ratio or the signal intensity. A distance d while the signal intensity is 1 / e of the maximum value indicates a two-dimensional spatial resolution.

Embodiment 7
FIG. 17 is a cross-sectional view showing the structure of the standard sample shown in Embodiment 7 of the present invention. The standard sample of this embodiment is suitable for vertical spatial resolution evaluation in near-field spectroscopic analysis. In FIG. 16, the standard sample 70 is composed of a base metal layer 71, a resin multilayer film 72, and a lattice metal mesh 73. The base metal layer 71 is the same metal plate as in the first to sixth embodiments or a glass substrate having a metal deposited on the surface thereof.

  The resin multilayer film 72 includes, for example, a first resin layer 72a made of a material that significantly includes C—F groups, a second resin layer 72b that is made of a material that significantly contains Si—O groups, and C═O. It includes a third resin layer 72c made of a material notably containing groups and a fourth resin layer 72d made of a material notably containing CH groups. The total thickness of the multilayer film 72 is the same as the thickness of the resin layer shown in the first to fourth embodiments, but the thickness of each resin layer is known. The lattice metal mesh 73 has the same material and configuration as the lattice metal mesh shown in the second to fourth embodiments.

  FIG. 18 is a diagram in which near-field spectroscopic analysis is performed on functional groups unique to each layer, and distribution mapping of each functional group is performed. Figure (a) shows the mapping results for the CH group, (b) for the C = O group, (c) for the Si-O group, and (d) for the C-F group. As is clear from these figures, in the C—H group mapping of FIG. (A) and the C═O group mapping of FIG. (B), the boundary between the resin portion and the metal lattice portion clearly appears, and therefore C It can be considered that the resin layer 72d containing —H groups and the resin layer 72c containing C═O groups have high detection sensitivity.

  On the other hand, in the figures (c) and (d), the boundary between the resin part and the metal lattice part is not clear or almost indistinguishable. Therefore, the resin layer 72b containing Si—O groups and the resin layer 72a containing C—F groups are considered to be indistinguishable.

  From the above results, in the resin multilayer film 72, the distance from the surface to the position of the resin layer 72c can be evaluated as the vertical spatial resolution in the near-field spectral analysis. In addition, since the layer thickness of each resin layer 72a-72d is known, the distance is computable.

  Although various embodiments of the present invention have been described above, the suitability of each standard sample is summarized as follows.

  First, the standard sample shown in Embodiments 1 to 5 is a sample that uses a boundary portion between an organic substance and an inorganic material for measurement of resolution, and is a sample suitable for evaluating how clearly the boundary portion can be identified. It is.

  On the other hand, the standard sample of Embodiment 6 is a sample suitable for evaluating the detection limit of the object size. Note that the double-grid sample shown in the fourth embodiment also has a detection limit for the object size, similar to the standard sample of the sixth embodiment, in that the resin region is changed by sliding each lattice and the detection limit region is evaluated. It can be said that it is a sample suitable for evaluating.

  While the standard samples shown in the first to sixth embodiments are samples for evaluating the resolution in the horizontal direction, the standard sample according to the seventh embodiment is a sample suitable for evaluating the vertical resolution.

  Moreover, each said embodiment has shown only one structural example about the characteristic, and it is clear that embodiments other than described embodiment are possible. For example, the multilayer film shown in Embodiment 7 can be applied to the resin layers shown in Embodiment 1, Embodiment 3 to Embodiment 5. Further, the structure of the base metal layer shown in Embodiment 3 can be applied to the base metal layer shown in Embodiments 1, 4 and 5.

The figure which shows the application principle of near field spectroscopy, and the definition of spatial resolution. The figure which shows the standard sample concerning Embodiment 1 of this invention. FIG. 5 is a diagram for explaining a method for determining the thickness of a metal coating layer, and showing the SB strength of a metal-coated polycarbonate. The figure which shows the near-field spectrum of the material which vapor-deposited the metal on the polycarbonate surface. The figure which shows the topographic image of the sample surface which has various level | step differences. The figure which shows the S / N sensitivity change of the CF group intensity | strength peak in a near-field spectroscopy spectrum with respect to the thickness change of a resin layer. (A) is a C-H group distribution visualization image when the standard sample of Embodiment 1 is used, (b) is a topographic image of the same sample, and (c) is a diagram showing an evaluation result of spatial resolution in the same sample. . The figure which shows the evaluation method of spatial resolution. The figure which shows the structure of the standard sample concerning Embodiment 2 of this invention. (A) is an optical microscope observation image of the standard sample of Embodiment 2, (b) is a C = O group distribution visualization image of the same sample, and (c) is a surface topographic image of the same sample. The figure which shows the evaluation result of the spatial resolution in the standard sample used by the measurement of FIG. The figure which shows the structure of the standard sample concerning Embodiment 3 of this invention. The figure which shows the structure of the standard sample concerning Embodiment 4 of this invention. The figure which shows the structure of the standard sample concerning Embodiment 5 of this invention. The figure which shows the structure of the standard sample concerning Embodiment 6 of this invention. The figure which shows the evaluation method of the spatial resolution about microparticles | fine-particles. The figure which shows the structure of the standard sample concerning Embodiment 7 of this invention. The figure which shows the near-field spectroscopy analysis result of the standard sample shown in FIG.

Explanation of symbols

10 Standard Sample 11 Base Metal Layer 12 Resin Layer 13 Metal Cover Layer 14 Boundary 15 Inclination (Slope)
20 Standard Sample 21 Base Metal Layer 22 Resin Layer 23 Grid Metal Mesh 30 Standard Sample 31 Base Metal Layer 32 Resin Layer 33 Grid Metal Mesh 34 Hole 35 Light Transmitting Crystal 36 Aperture 40 Standard Samples 43 and 44 First and Second Grid Metals Mesh 50 Standard sample 52 Grid metal mesh 53 Resin layer 60 Standard sample 62 Hole 63 Polymer fine particle 64, 65 Hydrophilic group 70 Standard sample 72 Resin multilayer film

Claims (13)

  A standard sample for spatial resolution evaluation in near-field spectroscopic analysis, a base metal layer whose surface is made of a highly reflective metal material, and a resin having a thickness of 10 μm or less formed on the base metal layer A standard sample comprising: a layer; and a metal layer partially covering the surface of the resin layer so that a boundary between the layer and the resin layer becomes clear.   The standard sample according to claim 1, wherein the resin layer includes at least one functional group among C—H, C═O, Si—O, and C—F functional groups. .   The standard sample according to claim 1, wherein the metal layer has a thickness of 3 μm or less.   The standard sample according to claim 1, wherein the metal layer has an inclination at a boundary portion with the resin layer.   2. The standard sample according to claim 1, wherein the metal layer is composed of a lattice metal mesh.   6. The standard sample according to claim 5, wherein the base metal layer has a plurality of hemispherical holes having a diameter approximately equal to a lattice interval of the lattice metal mesh on the upper surface portion, and the holes are light-transmitting. Standard sample, characterized in that it is filled with material.   The standard sample according to claim 5, wherein the lattice metal mesh is configured by first and second lattice metal meshes that can slide relative to the resin layer surface in a parallel direction. sample.   A standard sample for spatial resolution evaluation in near-field spectroscopy analysis, a base metal layer having a surface made of a highly reflective metal material, and a lattice metal having a thickness of 10 μm or less formed on the base metal layer A mesh and a resin layer filled in a portion surrounded by the lattice of the lattice metal mesh, and the surface of the lattice metal mesh and the surface of the resin layer are flattened so as to form the same plane. A standard sample characterized by   9. The standard sample according to claim 8, wherein metal fine particles are dispersed in the resin layer.   2. The standard sample according to claim 1, wherein the resin layer includes at least a first resin layer including a first functional group and a second functional group different from the first functional group. A standard sample having a structure in which a resin layer is laminated. Preparing a standard sample according to any one of claims 1 to 8,
Performing near-field spectroscopy measurement using the prepared standard sample;
Analyzing the measurement results to obtain a spectral peak intensity distribution based on a predetermined functional group;
Detecting a portion where the intensity value greatly changes in the obtained intensity distribution, and evaluating a spatial resolution in a horizontal direction in the near-field spectroscopic analysis based on a width of the detection portion. Evaluation method of spatial resolution in near-field spectroscopic analysis. Preparing a standard sample according to claim 7;
Performing near-field spectrometry while changing the lattice area by relatively sliding the first and second lattice metal meshes in the standard sample;
Analyzing the measurement results to obtain a spectral peak intensity distribution based on a predetermined functional group;
Obtaining a lower limit of identifiable resin regions defined by the lattice based on the obtained intensity distribution, and a method for evaluating spatial resolution in near-field spectroscopic analysis. Preparing a standard sample according to claim 10 ;
Performing near-field spectroscopy measurement using the prepared standard sample;
Analyzing the measurement result to determine an intensity distribution of a spectral peak based on the first and second functional groups;
Determining a lower limit value of the multilayer film in the standard sample that can be identified based on the obtained intensity distributions of the first and second functional groups, and a space in the near-field spectroscopic analysis, Resolution evaluation method.