Scanning probe microscope system and method for detecting detection object

Abstract

To provide an apparatus for identifying the type of chemical bond of a detection object with atomic level spatial resolution.SOLUTION: A scanning probe microscope apparatus comprises at least one probe placed in contact or non-contact with a detection object, a detection object support part, and a control unit for controlling the probe. The detection object support part has a function of converting electromagnetic waves into electrical signals, and the detection object support part has a function of converting the electromagnetic waves into electrical signals, and by capturing electromagnetic waves in the vicinity of the object and converting them into electrical signals, it is possible to identify chemical bonds in the object with high accuracy.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a scanning probe microscope system and a method for detecting a detection target.

Background Art

[0002] Since optical microscopes have a refractive limit of light, in principle, the resolution can only reach about half of the wavelength of light. In order to exceed the refractive limit of light, it is necessary to use near-field light. A scanning near-field microscope can map molecular species by measuring the spectrum of molecules beyond the diffraction limit of light. The spatial resolution of a scanning near-field microscope has achieved several nanometers. However, since the length of a chemical bond of a molecule is shorter than 1 nanometer, it is still impossible to obtain a scanning near-field microscope image of individual chemical bonds even with the technologies of Patent Document 1, Patent Document 2, Non-Patent Document 1, and Non-Patent Document 2. The reason is that the current measurement principle of a scanning near-field microscope uses light reflection or scattering and provides an external detector for detecting reflected or scattered light, so the detection dynamic range of light is narrow. That is, there is a problem with a conventional scanning probe microscope in which a light detector is installed at a location away from the scanning probe. Patent Document 3 uses an integrated optical probe to place the detector as close as possible to the scattered light to reduce the loss of scattered light, but it is still impossible to obtain a scanning near-field microscope image of individual chemical bonds with this technology.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Non - Patent Literature

[0004]

Non - Patent Literature 1

Non - Patent Literature 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Even with the above - mentioned Patent Document 1, Patent Document 2, Patent Document 3, Non - Patent Literature 1, and Non - Patent Literature 2, it has not been possible to accurately identify chemical bonds between atoms constituting a molecule at the order of individual chemical bonds.

[0006] The present invention has been made in view of the above, and an object thereof is to provide a scanning probe microscope device capable of accurately identifying chemical bonds in a detection target at the order of individual chemical bonds.

Means for Solving the Problems

[0007] (1) The present invention is a scanning probe microscope apparatus, which has at least one probe that is arranged in contact or non-contact with a detection object supported by a detection object support portion, and includes a control unit that controls the probe, a light source unit, and a signal detection unit. The detection object support portion has a function of converting an electromagnetic wave signal into an electrical signal. The probe is controlled by the control unit, and the electromagnetic wave signal irradiated from the light source unit is changed by the tip of the probe in the vicinity of the detection object, captured by the detection object support portion, converted into an electrical signal, and transferred to the signal detection unit, whereby the detection object can be identified.

[0008] According to this configuration, the electromagnetic wave irradiated from the light source is converted into an evanescent wave in the narrow space between the probe and the detection object support portion, the luminance of the light is enhanced to 1000 times or more of the irradiated wave luminance, and interacts with the chemical bond of the detection object. Further, since the intensity of the evanescent wave exponentially decays depending on the distance from the probe, the intensity of the evanescent wave changes exponentially by the sweeping of the probe. The intensity of the evanescent wave changes as a result of the interaction between the evanescent wave and the chemical bond of the detection object. The changed evanescent wave is converted into an electrical signal by an electromagnetic wave-electronic signal conversion unit that converts the electromagnetic wave arranged in the detection object support portion into an electrical signal, and transferred to the detection unit, whereby the nature of the chemical bond can be identified, and the chemical bond between atoms constituting the molecule can be accurately identified at the order of individual chemical bonds.

[0009] (2) The electromagnetic wave signal in the vicinity of the detection object in (1) is a second-order or higher-order harmonic wave including the second-order of the electromagnetic wave irradiated from the light source unit.

[0010] According to this configuration, if an evanescent wave is formed in the narrow space between the probe and the detection target support, the luminance of the light is enhanced to 1000 times or more the irradiation wave luminance, and second-order or higher-order harmonics of the irradiation wave are generated. If this higher-order harmonic is made to interact with the chemical bonds of the constituent molecules of the detection target and used for detection, it can be detected without being affected by the stray light of the incident wave, and the chemical bonds can be identified with high accuracy. The luminance of the electromagnetic wave referred to here is defined as the number of photons passing through a unit time and a unit area.

[0011] (3) In the scanning probe microscope of (1) above, the detection target support having a function of converting the electromagnetic wave into an electrical signal is composed of at least a conductor layer, a photoelectric conversion layer, and a conductor layer from the surface side.

[0012] According to this configuration, an evanescent wave is formed in the narrow space between the probe and the detection target support, and the electromagnetic wave after interacting with the chemical bonds of the constituent molecules of the detection target can pass through the conductor layer, be converted into an electrical signal by the photoelectric conversion layer, and reach the detection unit. With this configuration, it is possible to avoid the loss of light due to light scattering and perform detection with high accuracy.

[0013] (4) It is desirable that the photoelectric conversion layer of (3) above be composed of a PN junction of at least one P-type layer selected from silicon (Si) and germanium (Ge) and at least one N-type layer selected from silicon (Si) and germanium (Ge).

[0014] According to this configuration, the electromagnetic wave electrical signal conversion unit is composed of a PN junction of semiconductor silicon or germanium, and can effectively convert the electromagnetic wave signal into an electrical signal, and can detect electromagnetic waves in the X-ray region, ultraviolet region, visible light region, and near-infrared region with high accuracy.

[0015] (5) The photoelectric conversion layer of (3) above is copper indium selenide [CuInSe 2 , copper indium gallium selenide [Cu(InGa)Se 2It is preferably composed of a PN junction of at least one P-type layer selected from

[0016] According to this configuration, the electromagnetic wave electrical signal conversion unit is composed of a PN junction of a compound semiconductor, and can effectively convert an electromagnetic wave signal into an electrical signal. In particular, electromagnetic waves in the X-ray region, ultraviolet region, visible light region, and near-infrared region can be detected with high precision.

[0017] (6) In the scanning probe microscope of (1) above, the detection object support portion having a function of converting the electromagnetic wave into an electrical signal is composed of at least a conductor layer, a pyroelectric layer, and a conductor layer from the surface side.

[0018] According to this configuration, the electromagnetic wave electrical signal conversion unit is composed of a pyroelectric body, and can effectively change an electromagnetic wave signal into an electrical signal. In particular, electromagnetic waves in the near-infrared region, mid-infrared region, far-infrared region, and terahertz region can be detected with high precision.

[0019] (7) It is preferably composed of at least one layer selected from lead zirconate titanate (PZT), lead titanate (PbTiO 3 ), barium titanate (BaTiO 3 ), and L-alanine-doped triglycine sulfate deuterate (DLaTGS) for the pyroelectric layer of (6) above.

[0020] According to this configuration, if the above pyroelectric body is used, electromagnetic waves in the near-infrared region, mid-infrared region, far-infrared region, and terahertz region can be detected with high precision.

[0021] (8) In the scanning probe microscope of (1), the object support portion having a function of converting the electromagnetic wave into an electrical signal is composed of at least a conductor layer, an optical conductor layer, and a conductor layer from the surface side.

[0022] According to this configuration, the electromagnetic wave electrical signal conversion portion is composed of an optical conductor, the electrical conductivity of the optical conductor layer changes according to the intensity of the electromagnetic wave, and the electromagnetic wave signal can be effectively converted into an electrical signal.

[0023] (9) It is desirable that the optical conductor layer of (8) is composed of at least one layer selected from cadmium sulfide (CdS), cadmium selenide (CdSe), zinc sulfide (ZnS), zinc oxide (ZnO), lead sulfide (PbS), cadmium mercury telluride (CdHgTe), and selenium (Se).

[0024] According to this configuration, by using the above optical conductor, electromagnetic waves in the visible light region, near-infrared region, mid-infrared region, far-infrared region, and terahertz region can be detected with high precision.

[0025] (10) In the scanning probe microscope of (8), the object support portion having a function of converting the electromagnetic wave into an electrical signal is configured such that the optical conductor layer includes a quantum well structure.

[0026] According to this configuration, by using the above optical conductor, electromagnetic waves in the near-infrared region, mid-infrared region, far-infrared region, and terahertz region can be detected with high precision.

[0027] (11) In the scanning probe microscope of (8), the object support portion having a function of converting the electromagnetic wave into an electrical signal is configured such that the optical conductor layer includes a quantum dot structure.

[0028] According to this configuration, by using the above optical conductor, electromagnetic waves in the near-infrared region, mid-infrared region, far-infrared region, and terahertz region can be detected with high precision.

[0029] (12) In the scanning probe microscope of the above (8), the object support portion having a function of converting the electromagnetic wave into an electrical signal is configured such that the photoconductor layer includes a type-II superlattice structure.

[0030] According to this configuration, by using the above photoconductor, electromagnetic waves in the near-infrared region, mid-infrared region, far-infrared region, and terahertz region can be detected with high precision.

Advantages of the Invention

[0031] As described above, according to the configuration of (1) of the present invention, a scanning near-field microscope image of individual chemical bonds of molecules constituting the detection target can be obtained. Furthermore, according to the configurations of (2) to (12) that cite the above (1), additional effects can be obtained respectively.

[0032] In addition, in a known scanning probe microscope, the sample surface is observed by measuring the current flowing between the probe and the sample or the atomic force, but according to the electromagnetic wave detection device of the present invention, at least one of the shape of the detection target, the absorption of electromagnetic waves, and the electromagnetic wave emission phenomenon can be detected with high precision.

[0033] In addition, according to the present invention, if measurement is performed while controlling the position of the probe, it is not necessary to utilize the scattering of electromagnetic waves, so at least one behavior and position information of the shape, electromagnetic wave absorption, and electromagnetic wave emission of a minute region of the detection target can be simultaneously detected with high accuracy. Therefore, molecular bonds can be distinguished for each individual bond.

Brief Description of the Drawings

[0034]

Figure 1

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Figure 2

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Figure 3

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Figure 5

[0039]

Figure 6

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Figure 7

[0041]

Figure 8

[0042]

Figure 9

[0043]

Figure 10

Mode for Carrying Out the Invention

[0044] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0045] [Scanning Probe Microscope] FIG. 1 is a diagram showing the configuration of a scanning probe microscope according to an embodiment of the present invention. The probe 100 may be either in contact with or not in contact with the detection target 600. The apparatus includes at least a probe 100, a light source 200 for irradiating electromagnetic waves, a control unit 300 for controlling the position of the probe, a detection unit 500 for detecting an electrical signal obtained by converting an evanescent wave confined in a narrow space between the probe and the detection target support 800 into an electrical signal, an electromagnetic wave - electrical signal conversion unit 400 provided in a sample support unit for holding the detection target, and a detection target 600. A metal thin film 700 may be provided on the outermost surface of the detection target support 800. In one embodiment of the present invention, electromagnetic waves are irradiated from the light source 200 between the probe 100 and the sample support 800, and an evanescent wave is formed between the probe 100 and the sample support 800. The electromagnetic wave - electrical signal conversion unit 400 provided in the sample support converts the formed evanescent wave into an electrical signal, and the detection unit 500 detects the electrical signal. The detection target 600 disposed in the evanescent wave absorbs electromagnetic waves of a specific wavelength, weakening the intensity of the evanescent wave and thus weakening the evanescent wave received by the electromagnetic wave - electrical signal conversion unit 400. As a result, the electrical signal detected by the detection unit 500 also weakens. By sweeping the wavelength of the electromagnetic waves, the electromagnetic wave absorption spectrum of the detection target can be detected at the level of individual chemical bonds.

[0046] The electromagnetic waves converted by the electromagnetic wave - electrical signal conversion unit 400 may be higher - order harmonics of the second order or higher of the electromagnetic waves irradiated from the irradiation light source 200. Since the evanescent wave has high brightness, higher - order harmonics of the second order or higher are easily excited. According to the present invention, since the electromagnetic wave - electrical signal conversion unit 400 converts higher - order harmonics of the incident wave into an electrical signal, it can be converted without being affected by stray light of the incident wave, and thus has the characteristic of a high signal - to - noise ratio.

[0047] Another form of the present invention is the same as above until an evanescent wave is formed between the probe 100 and the sample support 800 in FIG. 1. However, after the detection target 600 absorbs electromagnetic waves of a specific wavelength, it emits electromagnetic waves of a wavelength different from the absorbed electromagnetic waves. The electromagnetic wave-to-electrical signal conversion unit 400 converts the emitted electromagnetic waves into electrical signals, and the detection unit 500 detects the electrical signals. According to this form, electromagnetic wave emission can be detected at the level of individual chemical bonds.

[0048] The wavelength of the electromagnetic wave absorbed by the detection target 600 may be the second or higher harmonic of the incident wave.

[0049] FIG. 2 is a diagram showing the configuration of a scanning probe microscope according to an embodiment of the present invention, and illustrates a chamber 900 that can control at least one of temperature, atmosphere, and vacuum. At least the probe 100, the sample support 800, and the detection target 600 are housed in the chamber 900 so that at least one of temperature, atmosphere, and degree of vacuum can be controlled. According to this embodiment, at least one of the detection requirements of the probe and the state of the detection target can be maintained in an optimal state, and the detection sensitivity can be increased.

[0050] [Electromagnetic wave-to-electrical signal conversion unit 400] FIG. 3 illustrates one form of the electromagnetic wave-to-electrical signal conversion unit 400 of the present invention. A cross-section of the electromagnetic wave-to-electrical signal conversion unit 400 is shown. The electromagnetic wave-to-electrical signal conversion unit 400 is composed of a conductor layer 401, a photoelectric conversion layer 402, and a conductor layer 403 from the side close to the detection target. The photoelectric conversion layer 402 converts the electromagnetic waves near the surface of the detection target support into electrical signals and transmits them to the detection unit 500. The configuration of the photoelectric conversion layer 402 can be composed of a PN junction of a semiconductor. The material of the semiconductor is not limited. Examples include single substances such as silicon (Si) and germanium (Ge), and compound semiconductors such as CuInSe2, Cu(InGa)Se2, ZnSe, GaAs, GaN, InP, InGaAlP, InGaN, CdS, ZnSe, ZnS, SiC, and SiGe.

[0051] Among them, the single-crystal semiconductor is preferably composed of at least one P-type layer selected from silicon (Si) and germanium (Ge) and at least one PN junction of an N-type selected from silicon (Si) and germanium (Ge) in the materials constituting the photoelectric conversion layer 402.

[0052] The compound semiconductor is such that the material constituting the photoelectric conversion layer 402 is at least one P-type layer selected from copper indium selenide [CuInSe 2 , copper indium gallium selenide [Cu(InGa)Se 2 , and at least one N-type layer selected from cadmium sulfide (CdS), zinc sulfide (ZnS), and zinc oxide (ZnO), preferably formed as a PN junction.

[0053] FIG. 4 illustrates one form of the electromagnetic wave - electrical signal conversion unit 400 of the present invention. It shows a cross-section of the electromagnetic wave - electrical signal conversion unit 400. The electromagnetic wave - electrical signal conversion unit 400 is composed of a conductor layer 401, a pyroelectric layer 404, and a conductor layer 403 from the side closer to the detection target. The pyroelectric layer 404 converts the electromagnetic wave near the surface of the detection target support into an electrical signal and transmits it to the detection unit 500. The material of the pyroelectric layer is not limited. Examples include lead zirconate titanate (PZT), lead titanate (PbTiO 3 ), barium titanate (BaTiO 3 ), L-alanine-doped triglycine sulfate (DLaTGS), cobalt phthalocyanine, lithium tantalate, polyvinyl fluoride, GaN, tourmaline, and the like.

[0054] Among them, it is desirable that the material constituting the pyroelectric layer 404 is composed of at least one material selected from lead zirconate titanate (PZT), lead titanate (PbTiO 3 ), barium titanate (BaTiO 3 ), and L-alanine-doped triglycine sulfate (DLaTGS).

[0055] FIG. 5 illustrates one form of the electromagnetic wave - electrical signal conversion unit 400 of the present invention. It shows a cross - section of the electromagnetic wave - electrical signal conversion unit 400. The electromagnetic wave - electrical signal conversion unit 400 is composed of, from the side close to the detection target, a conductor layer 401, a photoconductor layer 405, and a conductor layer 403. The photoconductor layer 405 converts the electromagnetic wave near the surface of the detection target support into an electrical signal and transmits it to the detection unit 500. The material constituting the photoconductor is not limited. By way of example, compounds such as cadmium sulfide (CdS), cadmium selenide (CdSe), zinc sulfide (ZnS), zinc oxide (ZnO), lead sulfide (PbS), cadmium mercury telluride (CdHgTe), etc., single - element substances such as selenium (Se), sulfur (S), tellurium (Te), phosphorus (P), arsenic (As), boron (B), silicon (Si), germanium (Ge), tin (Sn), etc., and doped semiconductors such as lithium - doped germanium can be mentioned.

[0056] Among them, it is desirable that the material constituting the photoconductor layer 405 is composed of at least one material selected from cadmium sulfide (CdS), cadmium selenide (CdSe), zinc sulfide (ZnS), zinc oxide (ZnO), lead sulfide (PbS), cadmium mercury telluride (CdHgTe), selenium (Se), and lithium - doped germanium.

[0057] FIG. 5 illustrates one form of the electromagnetic wave - electrical signal conversion unit 400 of the present invention. It shows a cross - section of the electromagnetic wave - electrical signal conversion unit 400. The electromagnetic wave - electrical signal conversion unit 400 is composed of, from the side close to the detection target, a conductor layer 401, a photoconductor layer, and a conductor layer 403, and the photoconductor layer is composed of a quantum well structure 406. The quantum well structure 406 converts the electromagnetic wave near the surface of the detection target support into an electrical signal and transmits it to the detection unit 500.

[0058] FIG. 6 illustrates one form of the electromagnetic wave - electrical signal conversion unit 400 of the present invention. It shows a cross - section of the electromagnetic wave - electrical signal conversion unit 400. The electromagnetic wave - electrical signal conversion unit 400 is composed of, from the side close to the detection target, a conductor layer 401, a photoconductor layer, and a conductor layer 403, and the photoconductor layer is composed of a quantum dot - type structure 407. The quantum well - type structure 407 converts the electromagnetic wave near the surface of the detection target support part into an electrical signal and transmits it to the detection unit 500.

[0059] FIG. 8 illustrates one form of the electromagnetic wave - electrical signal conversion unit 400 of the present invention. It shows a cross - section of the electromagnetic wave - electrical signal conversion unit 400. The electromagnetic wave - electrical signal conversion unit 400 is composed of, from the side close to the detection target, a conductor layer 401, a photoconductor layer, and a conductor layer 403, and the photoconductor layer is composed of a type - II superlattice - type structure 408. The type - II superlattice - type structure 408 converts the electromagnetic wave near the surface of the detection target support part into an electrical signal and transmits it to the detection unit 500.

[0060] FIGS. 9 and 10 show one form of the measurement example of the present invention. The irradiation of the electromagnetic wave may be from the back side of the sample support part 800. The shape of the sample support part is not particularly limited. Generally, a trapezoid, a triangular prism (FIG. 9), a semi - cylindrical shape (FIG. 10), a hemispherical shape (FIG. 10), etc. can be mentioned. According to this embodiment, the intensity of the incident electromagnetic wave is constant due to the irradiation from the back side, and it can be processed and removed as a background value by the detection unit 500, so it does not affect the detection accuracy.

Industrial Applicability

[0061] The scanning probe microscope apparatus and the electromagnetic wave - electrical signal conversion unit of the present invention can be used in the high - precision analysis instrument industry and the high - precision analysis service of substances. By using the scanning probe microscope apparatus of the present invention, the type of compound, the three - dimensional structure of the compound, the chirality of the compound, and the isotope of the element can be determined, and it can be applied as a new inspection method in the chemical industry, the pharmaceutical industry, and the inspection industry.

[0062] Note that the present invention is not limited to the above - mentioned embodiments, and modifications and improvements within the scope that can achieve the object of the present invention are included in the present invention.

[0063] Also, the figures are images for showing the structure and do not show exact dimensions.

Explanation of Signs

[0064] 10 Scanning probe microscope apparatus 100 Probe 200 Light source 300 Control unit 400 Electromagnetic wave - electrical signal conversion unit 401 Conductor layer 402 Photoelectric conversion body layer 403 Conductor layer 404 Pyroelectric body layer 405 Photoconductor layer 406 Quantum well - type structure photoconductor layer 407 Quantum dot - type structure photoconductor layer 408 Type - II superlattice - type structure photoconductor layer 500 Electrical signal detection unit 600 Object to be detected 700 Metal thin film 800 Object - to - be - detected support part 900 Chamber

Claims

1. A scanning probe microscope apparatus, comprising: at least one probe disposed in contact or non-contact with a detection object supported by a detection object support unit; a control unit for controlling the probe; a light source unit; and a signal detection unit, wherein the detection object support unit has a function of converting an electromagnetic wave signal into an electrical signal, the probe is controlled by the control unit, an electromagnetic wave signal irradiated from the light source unit is changed by the tip of the probe near the detection object, captured by the detection object support unit, converted into an electrical signal, and transferred to the signal detection unit, whereby the detection object can be identified.

2. The electromagnetic wave signal near the detection object according to Claim 1 is a second or higher order harmonic including the second order of the electromagnetic wave irradiated from the light source unit.

3. In the scanning probe microscope according to Claim 1, the detection object support unit having a function of converting the electromagnetic wave into an electrical signal includes, at least from the surface side, a conductor layer, a photoelectric conversion layer, and a conductor layer.

4. It is desirable that the photoelectric conversion layer according to Claim 3 is composed of a PN junction of at least one P-type layer selected from silicon (Si) and germanium (Ge) and at least one N-type layer selected from silicon (Si) and germanium (Ge).

5. The photoelectric conversion layer of claim 3 is composed of at least one P-type layer selected from copper indium selenide [CuInSe ２ , copper indium gallium selenide [Cu(InGa)Se ２ , and a PN junction of at least one N-type layer selected from cadmium sulfide (CdS), zinc sulfide (ZnS), and zinc oxide (ZnO).

6. In the scanning probe microscope according to Claim 1, the detection object support unit having a function of converting the electromagnetic wave into an electrical signal includes, at least from the surface side, a conductor layer, a pyroelectric layer, and a conductor layer.

7. The pyroelectric layer of claim 6 is composed of at least one layer selected from lead zirconate titanate (PZT), lead titanate (PbTiO ３ ), barium titanate (BaTiO ３ ), and L-alanine-doped triglycine sulfate (DLATGS).

8. In the scanning probe microscope according to Claim 1, the detection object support unit having a function of converting the electromagnetic wave into an electrical signal includes, at least from the surface side, a conductor layer, a photoconductor layer, and a conductor layer.

9. It is desirable that the photoconductor layer according to Claim 8 is composed of at least one layer selected from cadmium sulfide (CdS), cadmium selenide (CdSe), zinc sulfide (ZnS), zinc oxide (ZnO), lead sulfide (PbS), cadmium mercury telluride (CdHgTe), selenium (Se), and lithium-doped germanium.

10. In the scanning probe microscope according to Claim 8, the object support unit having a function of converting the electromagnetic wave into an electrical signal is configured such that the photoconductor layer includes a quantum well structure.

11. In the scanning probe microscope according to claim 8, the object support portion having a function of changing the electromagnetic wave into an electric signal is configured such that the photoconductive layer includes a quantum dot type structure.

12. In the scanning probe microscope according to claim 8, the object support portion having a function of converting the electromagnetic wave into an electric signal is configured such that the photoconductive layer includes a type-II superlattice type structure.

Images