JP2014059194A - Scanning probe microscope, and observation method of sample using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase intensity of detection light of near-field light generated between a measurement probe and an inspection object sample by expanding the NA of a detection optical system in a near-field scanning microscope, so as to improve an SN ratio and measurement reproducibility of a near-field optical image.SOLUTION: The present invention provides a scanning probe microscope including: a measurement probe that scans an inspection object sample; a laser irradiation system that irradiates the measurement probe with a laser beam; a sample holder that transmits scattering light of near-field light generated between the measurement probe and the inspection object sample due to the irradiation of the laser beam, and holds the inspection object sample; and a detector that detects the scattering light transmitted through the sample holder.

Description

  The present invention relates to a scanning probe microscope technique and a sample observation method using the same.

A scanning probe microscope as a measuring technique of the fine three-dimensional shape (SPM: S canning P robe M icroscope) is known. . Among them atomic force microscope (AFM: A tomic F orce M icroscope) are observed technique to scan the sample surface while keeping a very small value of the contact force by controlling the pointed tip of the tip, atomically It is widely used as a technique that can measure the fine three-dimensional shape. However, this atomic force microscope cannot measure optical properties such as reflectance distribution and refractive index distribution on the sample surface. On the other hand, strained silicon is applied to ultra-fine semiconductor devices of the 32 nm node and beyond for speeding up, but measurement of stress distribution in a minute region is indispensable for yield management. Further, for further miniaturization, it is required to finely manage the distribution of impurity atoms with a resolution of nanometer order. Physical properties information such as stress distribution and impurity distribution, CD-SEM used in the atomic force microscope and dimensional management: a (C ritical D imension S canning E lectron M icroscope measuring SEM) in unmeasurable. Optical techniques such as Raman spectroscopy have been studied, but a normal Raman spectroscopy microscope lacks spatial resolution.

  In addition, in order to identify the cause of occurrence of foreign matter and defects of several tens of nanometers detected by foreign matter inspection and defect inspection, classification work of foreign matters and defects is performed with an electron microscope called a review SEM. Since the method relies solely on the classification, the classification performance is limited. In this case, improvement of the classification performance can be expected by adding optical information. However, the normal optical microscope and the laser scanning microscope still lack spatial resolution.

To solve these problems, the optical properties and physical property information of the sample surface as a means of measuring a high resolution, the near-field scanning microscope (SNOM: S canning N ear- field O ptical M icroscope) is known. As disclosed in Non-Patent Document 1, this microscope scans near-field light leaking from a small aperture of several tens of nm while keeping the gap between the aperture and the sample at several tens of nm (opening). Probe), which measures optical properties such as reflectance distribution and refractive index distribution on the sample surface with a resolution of several tens of nanometers, which is the same size as the aperture, exceeding the diffraction limit of light. As a similar technique, Non-Patent Document 2 scans near-field light having a size of several tens of nanometers that is scattered from a minute tip of a probe by irradiating a metal probe with light from the outside (scattering probe). A method is also disclosed.

  Patent Document 1 discloses a method of forming a minute spot light by forming a minute spherical lens at the tip of a fiber as another form of the scattering probe.

  Similarly, in Patent Document 2, as another form of the scattering probe, metal carbides such as V, Y, Ta, and Sb that express photoluminescence and electroluminescence inside the carbon nanotube, ZnS phosphor, and CaS are disclosed. A method of filling a phosphor and obtaining a minute spot light is disclosed.

JP-T-2006-515682 JP 2002-267590 A

Japan Journal of Applied Physics, Vol. 31, pp. L1302-L1304 (1992) Optics Letters, Vol. 19, pp. 159-161 (1994)

In the near-field scanning microscope described above, the near-field light generated between the measurement probe and the sample to be inspected interacts with the measurement probe to generate scattered light (propagation light), and this scattered light is detected. The near-field light image was obtained effectively. However, in the near-field scanning microscope as described above, the detection lens for detecting the scattered light not be brought close to the sample, the detection NA: it is difficult to (N umerical A perture numerical aperture) larger. For this reason, in the near-field imaging and the spectroscopic imaging, the detected light amount is reduced, and the SN ratio and measurement reproducibility of the near-field light image are reduced.

  Therefore, an object of the present invention is to increase the detected light amount of the near-field light generated between the measurement probe and the sample to be inspected by enlarging the NA of the detection optical system in the near-field scanning microscope. It is to improve the SN ratio and measurement reproducibility of an optical image.

  In order to achieve the above object, the present invention provides a measurement probe for scanning a sample to be inspected, a laser irradiation system for irradiating the measurement probe with laser light, the measurement probe and the inspection by irradiating laser light. A scanning probe microscope including a sample holder that transmits scattered light of near-field light generated between the target sample and holds the sample to be inspected, and a detector that detects scattered light transmitted through the sample holder. provide.

  According to another aspect of the present invention, the measurement probe is scanned relative to the sample to be inspected, the laser probe is irradiated with the laser beam, and the measurement probe and the sample to be inspected are irradiated. Provided is a sample observation method using a scanning probe microscope, characterized by generating near-field light and detecting scattered light of the near-field light transmitted through a sample holder holding the sample to be inspected.

  According to the present invention, in the near-field scanning microscope, by increasing the NA of the detection optical system, the amount of detected near-field light generated between the measurement probe and the sample to be inspected is increased, and the near-field light image The S / N ratio and the measurement reproducibility can be improved.

2 is a front sectional view of a sample holder in Example 1. FIG. 6 is a front sectional view of a sample holder in Embodiment 2. FIG. 6 is a front sectional view of a sample holder in Example 3. FIG. 6 is a front sectional view of a sample holder in Example 4. FIG. 10 is a front sectional view of a sample holder in Example 5. FIG. 10 is a front sectional view of a sample holder in Example 6. FIG. 10 is a front sectional view of a sample holder in Example 7. FIG. 10 is a front sectional view of a sample holder in Example 8. FIG. 10 is a front sectional view of a sample holder in Example 9. FIG. FIG. 10 is a front sectional view of a sample holder in Example 10. 1 is a block diagram illustrating a schematic configuration of a scanning probe microscope in Examples 1, 2, and 3. FIG. It is a block diagram which shows the schematic structure of the scanning probe microscope in Example 4, 5, 6, 7, 8. 10 is a block diagram showing a schematic configuration of a scanning probe microscope in Example 9. FIG. FIG. 10 is a block diagram showing a schematic configuration of a scanning probe microscope in Example 10.

  Hereinafter, examples will be described with reference to the drawings. In the examples described below, any sample to be inspected is present in the liquid. However, the present invention is not limited to this, and the sample to be inspected present in the atmosphere is also included. Applicable.

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view showing a sample holder for mounting a sample to be inspected in the first embodiment. In this embodiment, as shown in FIG. 1, the sample 2 to be inspected is present in a solution 3 such as alcohol or water. The sample 2 to be inspected is held in the sample holder 1 together with the solution 3, and the sample holder 1 is further placed on an XY stage 4 driven by an actuator such as a piezoelectric element. A measurement probe 21 having a sharp tip made of metal such as gold or silver is brought close to the measurement sample 2 with the tip directed toward the measurement sample 2, and the gap between the measurement probe 21 and the surface of the sample 2 is measured. When the laser light 7 having a single wavelength is condensed from the oblique upper side by the condenser lens 6 and is irradiated to the tip of the measurement probe 21 when the tip is kept to be approximately equal to or less than the tip diameter of 21 or contacted with a minute contact force. A minute near-field light 8 is generated between the measurement probe 21 and the surface of the sample 2, and scattered light (propagation light) 9 is generated by the interaction between the near-field light 8 and the measurement probe 21.

Here, the sample holder 1 is made of a material that allows the scattered light 9 to pass through, and its side surface is formed of a curved surface 1a having a certain curvature, and functions as a detection lens. As a result, the scattered light 9 is transmitted through the sample holder 1 and the lens effect of the curved surface 1a (refracted light from one point is refracted at a predetermined angle to become parallel light, condensed, diverged, or After being converted into parallel light, it is condensed by the imaging lens 10 and received by a detector 11 such as a photomultiplier tube or a photodiode. In order to suppress reflection at the interface between the inner wall of the sample holder 1 and the solution 3, it is desirable that the refractive index of the sample holder 1 is close to the refractive index of the solution. According to the sample holder 1, since an equivalent when effectively place the detecting lens to a range of close proximity to several mm of the sample 2, a large NA (N umerical A perture: aperture; light emitted from a certain point It is a lens evaluation index corresponding to the maximum angle that can be captured, and the larger the NA, the more light can be captured), so that the detected light can be captured, the detected light quantity increases dramatically, the SN ratio and measurement of the near-field light image Reproducibility is improved.

  FIG. 11 shows the configuration of a scanning probe microscope incorporating this sample holder. The scanning probe microscope includes a sample holder 1 that mounts a sample 2 and detects scattered light, an XY piezoelectric element stage 4 that mounts the sample holder 1 and scans the sample 2 in the XY directions, and a measurement probe that scans the sample 2 at the tip. By detecting the deflection of the cantilever 25 as a support portion to which the needle 21 is fixed, the piezoelectric element actuator 26 for minutely vibrating the cantilever 25 in the Z direction, the Z piezoelectric element stage 27 for scanning the cantilever 15 in the Z direction, An optical lever detection system 95 that detects the contact force between the measurement probe and the sample, an excitation laser irradiation system 70 that irradiates the tip of the measurement probe 21 with the laser beam 7, and a scattered light detection that condenses the scattered light and photoelectrically converts it. The system 200 includes a signal processing / control system 300 that generates and outputs a near-field light image and a concavo-convex image from the obtained scattered light signal and XYZ displacement signal. The XY piezoelectric element stage 4 and the Z piezoelectric element stage 27 constitute a drive unit that scans the measurement probe 21 relative to the sample 2.

  In the optical lever detection system 95, the back surface of the cantilever 25 is irradiated with the laser light 72 from the semiconductor laser 71, the reflected light is received by the quadrant sensor 73, and the deflection amount of the cantilever 25 is detected from the change in the position of the reflected light. Further, the Z piezoelectric element stage 27 is detected by the control unit 100 of the signal processing / control system 300 so that the contact force between the measurement probe 21 and the sample 2 is detected from the deflection amount and the contact force always becomes a preset value. Feedback control.

  Since the measurement probe 21 is minutely vibrated in the Z direction at the resonance frequency of the cantilever 25 by the oscillator 80, the generated near-field light 8 and scattered light 9 are intensity-modulated at the same frequency. The intensity-modulated optical signal output from the detector 11 is synchronously detected by the lock-in amplifier 90, and only this frequency component is output. The background scattered light directly scattered at the root of the measurement probe and the sample surface by the excitation laser beam 7 does not react to the minute vibration of the cantilever 25 and is a direct current component, and therefore is included in the output signal of the lock-in amplifier 90. I can't. Thereby, it is possible to selectively detect only the near-field light component while suppressing the background noise. The signal SN ratio can be further improved by detecting harmonic components such as the second harmonic and the third harmonic of the resonance frequency.

  The optical signal from the lock-in amplifier 90 is sent to the control unit 100 of the signal processing / control system 300, combined with the XY signal from the XY piezoelectric element stage 4 to generate a near-field light image and output to the display 110. . At the same time, the Z signal from the Z piezoelectric element stage 27 is also combined with the XY signal by the control unit 100 to generate a concavo-convex image of the sample surface and output to the display 110.

  According to the present embodiment, as described above, it is equivalent to effectively disposing the detection lens in the range of several millimeters in the vicinity of the sample 2, so that the detection light can be captured with a large NA, and the detection light quantity is remarkably increased. This increases the S / N ratio and measurement reproducibility of the near-field light image.

  As a result, it is possible to measure optical information, spectral information, and unevenness information on the sample surface with a resolution of nanometer order, a high S / N ratio, and a high measurement reproducibility. As a result, physical property information such as stress distribution and impurity distribution of semiconductor samples, spectral information, and surface unevenness information can be measured. In addition, since optical information and unevenness information that contribute to the classification of foreign matter and defects can be measured, the foreign matter / defect classification performance is improved. Further, by feeding back these measurement results to the semiconductor manufacturing process conditions, it becomes possible to produce a highly reliable semiconductor device with a high yield.

  A second embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a cross-sectional view showing a sample holder for mounting a sample to be inspected in the second embodiment. Since the form and function of the sample holder 1 are the same as those of the first embodiment, description thereof is omitted. In this embodiment, the form of the measurement probe is different. The measurement probe 22 is coated with a metal film 22b made of gold, silver, or the like around the quartz fiber 22a with a sharpened tip directed toward the sample 2, and a minute opening is formed by removing the metal film only at the tip directed toward the sample 2. It is a thing. When the laser light 7 is condensed by the condenser lens 6 and irradiated from above the quartz fiber 22a (the side opposite to the side where the sample 2 is present with respect to the measurement probe 22), it approaches from the opening at the tip of the measurement probe 22. A field light 8 is generated, and a scattered light (propagating light) 9 is generated by the interaction between the near-field light 8 and the measurement probe 22.

  FIG. 11 shows the configuration of a scanning probe microscope incorporating this sample holder. Since the configuration and function of this scanning probe microscope are the same as those of the first embodiment, description thereof is omitted.

  According to the present embodiment, as described above, it is equivalent to effectively disposing the detection lens in the range of several millimeters in the vicinity of the sample 2, so that the detection light can be captured with a large NA, and the detection light quantity is remarkably increased. This increases the S / N ratio and measurement reproducibility of the near-field light image. In this embodiment, since the near-field light 8 is generated by irradiating the laser beam 7 through the quartz fiber 22a, the influence of the background noise is larger than that in the first embodiment in which the laser beam 7 is irradiated on the tip of the measurement probe. There is an advantage of being small.

A third embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a cross-sectional view showing a sample holder for mounting a sample to be inspected in the third embodiment. Since the form and function of the sample holder are the same as those in the first embodiment, description thereof is omitted. In this embodiment, the form of the measurement probe is different. Measurement probe 23, carbon diameter of the tip for directing the sample 2 is sharpened to several nm nanotubes (C arbon N ano t ube: CNT) consists. The CNTs may be filled with gold nanostructures or silver nanostructures. As shown in FIG. 11, this measurement probe is fixed to the tip of the cantilever 25, and the excitation laser beam 7 is irradiated obliquely from above (the side opposite to the side where the sample 2 is present with respect to the measurement probe 22). The This laser beam 7 is converted into plasmons which are collective vibrations of free electrons of CNTs, and as shown by the broken lines in FIG. From the side) to the lower end (the side where the sample 2 is present), and the electric field is concentrated at the tip portion to generate near-field light 8a. Further, scattered light (propagation light) 9 is generated by the interaction between the near-field light 8 a and the measurement probe 23.

  FIG. 11 shows the configuration of a scanning probe microscope incorporating this sample holder. Since the configuration and function of this scanning probe microscope are the same as those of the first embodiment, description thereof is omitted.

  According to the present embodiment, as described above, it is equivalent to effectively disposing the detection lens in the range of several millimeters in the vicinity of the sample 2, so that the detection light can be captured with a large NA, and the detection light quantity is remarkably increased. This increases the S / N ratio and measurement reproducibility of the near-field light image. In the present embodiment, since the CNT having a tip diameter of several nanometers is used for the measurement probe 23, the spatial resolution is several nanometers, and the spatial resolution is improved by about 10 times compared to the first and second embodiments. To do.

  A fourth embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a cross-sectional view showing a sample holder for mounting a sample to be inspected in the fourth embodiment. In this embodiment, as shown in FIG. 4, the sample 2 to be inspected exists in a solution 3 such as alcohol or water. The sample 2 to be inspected is held in the sample holder 31 together with the solution 3, and the sample holder 31 is further placed on an XY stage 40 having an opening in the center driven by an actuator such as a piezoelectric element. A measurement probe 21 having a sharp tip made of a metal such as gold or silver is brought close to the measurement sample 2, and the gap between the measurement probe 21 and the surface of the sample 2 is approximately the same as the tip diameter of the measurement probe 21. If the laser light 7 is condensed by the condensing lens 6 and irradiated to the tip of the measurement probe 21 from the oblique upper side, the distance between the measurement probe 21 and the surface of the sample 2 is maintained. A very small near-field light 8 is generated, and scattered light (propagating light) 17 is generated by the interaction between the near-field light 8 and the measurement probe 21.

  Here, the sample holder 31 is made of a material that allows the scattered light 17 to pass therethrough, and its bottom surface is made of a curved surface 31a having a certain curvature, and functions as a detection lens. As a result, the scattered light 17 passes through the sample holder 31 and becomes parallel light due to the lens effect of the curved surface 31a. After passing through the opening of the XY stage 40, the scattered light 17 is collected by the imaging lens 18 and is collected by a photomultiplier tube or photodiode. Is received by a detector 19. In order to suppress reflection at the interface between the inner wall of the sample holder 31 and the solution 3, the refractive index of the sample holder 31 is preferably close to the refractive index of the solution. According to this sample holder 31, since it is equivalent to effectively disposing the detection lens in the range of several millimeters in the vicinity of the sample 2, the detection light can be captured with a large NA, and the detection light quantity is greatly increased. The SN ratio and measurement reproducibility of the near-field light image are improved.

  FIG. 12 shows the configuration of a scanning probe microscope incorporating this sample holder. In this scanning probe microscope, the configuration other than the sample holder 31 and the function thereof are the same as those in the first embodiment, and thus description thereof is omitted.

  According to the present embodiment, as described above, it is equivalent to effectively disposing the detection lens in the range of several millimeters in the vicinity of the sample 2, so that the detection light can be captured with a large NA, and the detection light quantity is remarkably increased. This increases the S / N ratio and measurement reproducibility of the near-field light image. Furthermore, in the present embodiment, the configuration is such that the side scattered light is not detected as in the first to third embodiments, but the forward scattered light is detected from the bottom surface of the sample holder 31. As shown in FIG. 5, the NA of detection can be further increased, the amount of detected scattered light can be significantly increased, and the SN ratio and measurement reproducibility of the near-field light image can be improved.

  A fifth embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a cross-sectional view showing a sample holder for mounting a sample to be inspected in the fifth embodiment. Since the form and function of the sample holder 31 are the same as those of the fourth embodiment, description thereof is omitted. In this embodiment, the form of the measurement probe is different. The measurement probe 22 is formed by coating the periphery of a quartz fiber 22a with a sharpened tip with a metal film 22b such as gold or silver, and removing the metal film only at the tip to form a minute opening. When the laser beam 7 is condensed by the condenser lens 6 and irradiated from above the quartz fiber 22a, near-field light 8 is generated from the opening at the tip of the measurement probe 22, and the near-field light 8 and the measurement probe 22 are further generated. Scattered light (propagating light) 17 is generated by the interaction with the.

  FIG. 12 shows the configuration of a scanning probe microscope incorporating this sample holder. Since the configuration and function of this scanning probe microscope are the same as those of the first embodiment, description thereof is omitted.

  According to the present embodiment, as described above, it is equivalent to effectively disposing the detection lens in the range of several millimeters in the vicinity of the sample 2, so that the detection light can be captured with a large NA, and the detection light quantity is remarkably increased. This increases the S / N ratio and measurement reproducibility of the near-field light image. Furthermore, in the present embodiment, the configuration is such that the side scattered light is not detected as in the first to third embodiments, but the front scattered light is detected from the bottom surface of the sample holder 31, and therefore FIG. As shown in FIG. 5, the NA of detection can be further increased, the amount of detected scattered light can be significantly increased, and the SN ratio and measurement reproducibility of the near-field light image can be improved.

A sixth embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a cross-sectional view showing a sample holder on which a sample to be inspected is mounted in the sixth embodiment. Since the form and function of the sample holder 31 are the same as those of the fourth embodiment, description thereof is omitted. In this embodiment, the form of the measurement probe is different. Measurement probe 23, carbon nanotube tip diameter is sharpened to several nm (C arbon N ano t ube : CNT), or consists of CNT filled with gold nanoparticles and silver nanostructures therein. As shown in FIG. 12, this measurement probe is fixed to the tip of the cantilever 25, and the excitation laser beam 7 is irradiated obliquely from above. This laser light 7 is converted into plasmons which are collective vibrations of free electrons, and propagates from the upper end to the lower end of the CNT as surface plasmons 15 as shown by the broken lines in FIG. Occurs. Further, scattered light (propagating light) 17 is generated by the interaction between the near-field light 8 a and the measurement probe 23.

  FIG. 12 shows the configuration of a scanning probe microscope incorporating this sample holder. Since the configuration and function of this scanning probe microscope are the same as those of the first embodiment, description thereof is omitted.

  According to the present embodiment, as described above, it is equivalent to effectively disposing the detection lens in the range of several millimeters in the vicinity of the sample 2, so that the detection light can be captured with a large NA, and the detection light quantity is remarkably increased. This increases the S / N ratio and measurement reproducibility of the near-field light image. Furthermore, in the present embodiment, it is not a configuration for detecting side scattered light as in the first to third embodiments, but a configuration for detecting forward scattered light from the bottom surface of the sample holder 31, that is, FIG. As shown in FIG. 5, the NA of detection can be further increased, the amount of detected scattered light can be significantly increased, and the SN ratio and measurement reproducibility of the near-field light image can be improved. In the present embodiment, since the CNT having a tip diameter of several nanometers is used for the measurement probe 23, the spatial resolution is several nanometers, and the spatial resolution is improved by about 10 times compared to the first and second embodiments. To do.

  A seventh embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a cross-sectional view showing a sample holder for mounting a sample to be inspected in the seventh embodiment. In this embodiment, as shown in FIG. 7, the sample 2 to be inspected exists in a solution 3 such as alcohol or water. The sample 2 to be inspected is held together with the solution 3 in a sample holder 41, and the sample holder 41 is further placed on an XY stage 40 having an opening in the center driven by an actuator such as a piezoelectric element. A measurement probe 21 having a sharp tip made of a metal such as gold or silver is brought close to the measurement sample 2, and the gap between the measurement probe 21 and the surface of the sample 2 is approximately the same as the tip diameter of the measurement probe 21. If the laser light 7 is condensed by the condensing lens 6 and irradiated to the tip of the measurement probe 21 from the oblique upper side, the distance between the measurement probe 21 and the surface of the sample 2 is maintained. A very small near-field light 8 is generated, and scattered light (propagating light) 17 is generated by the interaction between the near-field light 8 and the measurement probe 21.

  Here, the sample holder 41 is made of a material that allows the scattered light 17 to pass through, and the Fresnel lens 41a is formed on the bottom surface of the sample holder 41 by forming a diffraction grating with unequal intervals on the bottom surface. The light is diffracted at a predetermined angle to be collimated, condensed, diverged, or vice versa, and functions as a detection lens. As a result, the scattered light 17 passes through the sample holder 41 to become parallel light by the Fresnel lens 41a, passes through the opening of the XY stage 40, and is then collected by the imaging lens 18, and is used as a photomultiplier tube or a photodiode. The light is received by the detector 19. In order to suppress reflection at the interface between the inner wall of the sample holder 41 and the solution 3, it is desirable that the refractive index of the sample holder 41 is close to the refractive index of the solution. According to the sample holder 41, since it is equivalent to disposing the detection lens in a range of several millimeters in the vicinity of the sample 2 effectively, the detection light can be captured with a large NA, and the detection light amount is remarkably increased. The SN ratio and measurement reproducibility of the near-field light image are improved.

  FIG. 12 shows the configuration of a scanning probe microscope incorporating this sample holder. In this scanning probe microscope, the configuration other than the sample holder 41 and the function thereof are the same as those in the first embodiment, and thus description thereof is omitted.

  According to the present embodiment, as described above, it is equivalent to effectively disposing the detection lens in the range of several millimeters in the vicinity of the sample 2, so that the detection light can be captured with a large NA, and the detection light quantity is remarkably increased. This increases the S / N ratio and measurement reproducibility of the near-field light image. Furthermore, in the present embodiment, the bottom surface of the sample holder 41 is configured by a Fresnel lens instead of a lens having a curvature, so that the thickness of the bottom surface can be reduced and the cost of the sample holder 41 can be reduced. Have.

  An eighth embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a cross-sectional view showing a sample holder for mounting a sample to be inspected in the eighth embodiment. In the present embodiment, as shown in FIG. 8, the sample 2 to be inspected exists in a solution 3 such as alcohol or water. The sample 2 to be inspected is held in the sample holder 51 together with the solution 3, and the sample holder 51 is further placed on an XY stage 40 having an opening at the center driven by an actuator such as a piezoelectric element. A measurement probe 21 having a sharp tip made of a metal such as gold or silver is brought close to the measurement sample 2, and the gap between the measurement probe 21 and the surface of the sample 2 is approximately the same as the tip diameter of the measurement probe 21. If the laser light 7 is condensed by the condensing lens 6 and irradiated to the tip of the measurement probe 21 from the oblique upper side, the distance between the measurement probe 21 and the surface of the sample 2 is maintained. A very small near-field light 8 is generated, and scattered light (propagating light) 17 is generated by the interaction between the near-field light 8 and the measurement probe 21.

  Here, the sample holder 51 is made of a material through which the scattered light 17 is transmitted, and the bottom thereof is formed by a refractive index distribution lens 51a having a large refractive index at the center and a refractive index decreasing toward the periphery. Functions as a lens. As a result, the scattered light 17 is transmitted through the sample holder 51 to become parallel light by the refractive index distribution lens 51a, passes through the opening of the XY stage 40, and is then collected by the imaging lens 18, and is photomultiplier tube or photodiode. Is received by a detector 19. According to this sample holder 51, it is equivalent to effectively arranging the detection lens in a range of several millimeters in the vicinity of the sample 2, so that the detection light can be captured with a large NA, and the detection light quantity is remarkably increased. The SN ratio and measurement reproducibility of the near-field light image are improved.

  FIG. 12 shows the configuration of a scanning probe microscope incorporating this sample holder. In this scanning probe microscope, the configuration other than the sample holder 51 and the function thereof are the same as those in the first embodiment, and thus the description thereof is omitted.

  According to the present embodiment, as described above, it is equivalent to effectively disposing the detection lens in the range of several millimeters in the vicinity of the sample 2, so that the detection light can be captured with a large NA, and the detection light quantity is remarkably increased. This increases the S / N ratio and measurement reproducibility of the near-field light image. Further, in this embodiment, since the bottom surface of the sample holder 41 is constituted by a refractive index distribution lens, the surface processing of the bottom surface becomes unnecessary, and the cost of the sample holder 41 is reduced.

A ninth embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a cross-sectional view showing a sample holder for mounting a sample to be inspected in the ninth embodiment. In the present embodiment, as shown in FIG. 9, the sample 2 to be inspected exists in a solution 3 such as alcohol or water. The sample 2 to be inspected is held together with the solution 3 in a sample holder 61, and the sample holder 61 is further placed on an XY stage 40 having an opening in the center driven by an actuator such as a piezoelectric element. Measurement probe 23, carbon nanotube tip diameter is sharpened to several nm (C arbon N ano t ube : CNT), or consists of CNT filled with gold nanoparticles and silver nanostructures therein. As shown in FIG. 13, this measurement probe is fixed to the tip of the cantilever 25, and the excitation laser beam 7 is irradiated obliquely from above. The laser light 7 is converted into plasmons which are collective vibrations of free electrons, and propagates from the upper end to the lower end of the CNT as surface plasmons 15 as shown by the broken lines in FIG. Occurs. Further, scattered light (propagating light) 17 is generated by the interaction between the near-field light 8 a and the measurement probe 23.

  Here, the sample holder 61 is made of a material that allows the scattered light 17 to pass through, and has a spherical ball lens 61a (with a spherical surface that refracts light by processing a concave sample holding portion 61b on the upper side. The light emitted from one point can be converted into parallel light, condensed, diverged, or vice versa, and functions as a detection lens. As a result, the scattered light 17 is transmitted through the sample holder 61 to become parallel light by the ball lens 61a, passes through the opening of the XY stage 40, and is then collected by the imaging lens 18, and a photomultiplier tube, a photodiode, or the like. The light is received by the detector 19. According to the sample holder 61, it is equivalent to effectively arranging the detection lens in a range of several millimeters in the vicinity of the sample 2, so that the detection light can be captured with a large NA, and the detection light quantity is remarkably increased. The SN ratio and measurement reproducibility of the near-field light image are improved.

  FIG. 13 shows the configuration of a scanning probe microscope incorporating this sample holder. In this scanning probe microscope, the configuration other than the sample holder 61 and the function thereof are the same as those in the first embodiment, and thus description thereof is omitted.

  According to the present embodiment, as described above, it is equivalent to effectively disposing the detection lens in the range of several millimeters in the vicinity of the sample 2, so that the detection light can be captured with a large NA, and the detection light quantity is remarkably increased. This increases the S / N ratio and measurement reproducibility of the near-field light image. In the present embodiment, since the CNT having a tip diameter of several nanometers is used for the measurement probe 23, the spatial resolution is several nanometers, and the spatial resolution is improved by about 10 times compared to the first and second embodiments. To do. Furthermore, in the present embodiment, the sample holder 61 is configured by a simple ball lens, which has the effect of reducing the processing cost of the sample holder 41.

A tenth embodiment of the present invention will be described with reference to FIGS. FIG. 10 is a cross-sectional view showing a sample holder for mounting a sample to be inspected in the tenth embodiment. In the present embodiment, as shown in FIG. 10, the inspection target sample 2 is present in a solution 3 such as alcohol or water. The sample 2 to be inspected is held together with the solution 3 in a sample holder 61, and the sample holder 61 is further placed on an XY stage 40 having an opening in the center driven by an actuator such as a piezoelectric element. Measurement probe 23, carbon nanotube tip diameter is sharpened to several nm (C arbon N ano t ube : CNT), or consists of CNT filled with gold nanoparticles and silver nanostructures therein. As shown in FIG. 14, this measurement probe is fixed to the tip of the cantilever 25, and the excitation laser beam 7 is irradiated obliquely from above. This laser light 7 is converted into plasmons which are collective vibrations of free electrons, and propagates from the upper end to the lower end of the CNT as surface plasmons 15 as shown by the broken lines in FIG. Occurs. Further, scattered light (propagating light) 9 and 17 is generated by the interaction between the near-field light 8 a and the measurement probe 23.

  Here, as in the ninth embodiment, the sample holder 61 is made of a material through which the scattered light 9 and 17 is transmitted, and is formed of a spherical ball lens 61a in which a concave sample holder 61b is processed at the top. And function as a detection lens. As a result, the scattered lights 9 and 17 are transmitted through the sample holder 61 to become parallel lights by the ball lens 61a, and are collected by the imaging lenses 10 and 18, and are detected by the detectors 11 and 19 such as photomultiplier tubes and photodiodes. Received light. According to the sample holder 61, it is equivalent to effectively arranging the detection lens in a range of several millimeters in the vicinity of the sample 2, so that the detection light can be captured with a large NA, and the detection light quantity is remarkably increased. The SN ratio and measurement reproducibility of the near-field light image are improved.

  FIG. 14 shows the configuration of a scanning probe microscope incorporating this sample holder. In the scattered light detection system 200, the optical signals from the detectors 11 and 19 are added by an adder 85 and then synchronously detected by a lock-in amplifier 90. Since the subsequent processes, functions, and overall configuration are the same as those in the first embodiment, description thereof will be omitted.

  According to the present embodiment, as described above, it is equivalent to effectively disposing the detection lens in the range of several millimeters in the vicinity of the sample 2, so that the detection light can be captured with a large NA, and the detection light quantity is remarkably increased. This increases the S / N ratio and measurement reproducibility of the near-field light image. In the present embodiment, since the CNT having a tip diameter of several nanometers is used for the measurement probe 23, the spatial resolution is several nanometers, and the spatial resolution is improved by about 10 times compared to the first and second embodiments. To do. Furthermore, in the present embodiment, the sample holder 61 is constituted by a simple ball lens, which has the effect of reducing the processing cost of the sample holder 61. Further, in this embodiment, since the two scattered lights of the side scattered light and the forward scattered light are detected, the detected light amount is further increased compared to the first to ninth embodiments, and the near-field light image is displayed. The SN ratio and measurement reproducibility are improved.

  In all the embodiments described above, the excitation laser beam 7 is monochromatic light. However, the present invention is not limited to this, and laser beams having three wavelengths of red, green, and blue are used. Color near-field imaging can also be performed. It is also possible to perform near-field spectroscopic measurement using a white laser beam and a spectroscope, or to perform near-field Raman spectroscopic measurement that detects, for example, a Raman-shifted wavelength instead of the same wavelength as the excitation laser beam. Is possible.

1, 31, 41, 51, 61 ... Sample holder 2 ... Sample 3 ... Solution 4, 40 ... XY piezoelectric element stage 8, 8a ... Near field light 9, 17 ... Scattering Lights 11, 19 ... Detectors 21, 22, 23 ... Measuring probe 25 ... Cantilever 26 ... Piezoelectric element actuator 27 ... Z piezoelectric element stage 70 ... Excitation laser irradiation system 80 ..Oscillator 90 ... Lock-in amplifier 95 ... Optical lever detection system 100 ... Control unit 110 ... Display 200 ... scattered light detection system 300 ... Signal processing / control system

Claims (16)

A measurement probe that scans the sample to be inspected;
A laser irradiation system for irradiating the measurement probe with laser light; and
A sample holder that transmits the scattered light of the near-field light generated between the measurement probe and the sample to be inspected by laser light irradiation, and holds the sample to be inspected;
A scanning probe microscope comprising: a detector that detects scattered light transmitted through the sample holder.   The scanning probe microscope according to claim 1, wherein the surface of the sample holder is formed of a curved surface.   The scanning probe microscope according to claim 1, wherein a Fresnel lens is formed on the surface of the sample holder.   The scanning probe microscope according to claim 1, wherein the sample holder is formed of a gradient index lens.   The scanning probe microscope according to claim 1, wherein the sample holder is formed of a ball lens. The measurement probe has a sharpened tip side toward the sample to be inspected,
2. The scanning probe microscope according to claim 1, wherein the laser beam irradiation system irradiates a laser beam to a tip of the measurement probe. The measurement probe has a minute opening formed at the tip toward the sample to be inspected,
2. The scanning according to claim 1, wherein the laser beam irradiation system generates the near-field light from the minute aperture by irradiating a laser beam on the opposite side of the measurement probe from the sample to be inspected. Probe microscope.   The laser beam irradiation system generates a surface plasmon on the measurement probe by irradiating a laser beam on the opposite side of the measurement probe with respect to the sample to be inspected, and a tip that faces the surface plasmon toward the sample to be inspected. The scanning probe microscope according to claim 1, wherein the scanning probe microscope is propagated sideways. Scan the measurement probe relative to the sample to be inspected,
Irradiate the measurement probe with laser light,
The near field light is generated between the measurement probe and the sample to be inspected,
A method for observing a sample using a scanning probe microscope, wherein the scattered light of the near-field light transmitted through a sample holder holding the sample to be inspected is detected.   The scanning probe microscope according to claim 9, wherein the surface of the sample holder is a curved surface.   The scanning probe microscope according to claim 9, wherein a Fresnel lens is formed on the surface of the sample holder.   The scanning probe microscope according to claim 9, wherein the sample holder is formed of a refractive index distribution lens.   The scanning probe microscope according to claim 9, wherein the sample holder is formed of a ball lens.   The scanning probe microscope according to claim 9, wherein a laser beam is irradiated to a tip side of the measurement probe toward the inspection target sample.   By irradiating a laser beam on the opposite side of the measurement probe from the sample to be inspected, the near-field light is generated from a minute opening formed at a tip of the measurement probe toward the sample to be inspected. The scanning probe microscope according to claim 9.   By irradiating the measurement probe with a laser beam on the opposite side of the sample to be inspected, surface plasmon is generated in the measurement probe, and the surface plasmon is propagated to the tip side toward the sample to be inspected. The scanning probe microscope according to claim 9.

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