JP2001033464A - Near-field optical microscope and proble for it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an SNOM(scanning-type near-field optical microscope) that can be operated in air for obtaining a high-resolution SNOM image where the influence of scattered light from an area other than the tip of a probe has been eliminated as much as possible. SOLUTION: Slide glass 2 where a sample 1 is placed is arranged on an internal total reflection prism 3 through matching oil 4. A laser beam is applied to the sample 1 through the prism 3, and a proximity field is generated on the sample surface. A probe 106 that is supported by the free end of a cantilever 101 is arranged at the upper portion of the sample 1, and an objective lens 19 is arranged at the upper portion. The objective lens 19 is arranged and a scattered light detection mirror cylinder 222 is arranged at the upper portion of the objective lens 19, thus composing a scattered light detection optical system for detecting scattered light being generated due to the entry of the probe 106 into the near field. The probe 106 is in a tetrapod shape and has an extension part 107 being extended in one direction. The thickness of the extension part 107 is the maximum over length from the tip to the wavelength or more of incident light and is within three times larger or less of the tip diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a near-field light microscope which obtains information on a sample surface by detecting scattered light generated when a probe enters a near field.

[0002]

2. Description of the Related Art A scanning probe microscope (SPM) scans a probe in an XY direction or an XYZ direction while detecting an interaction between the probe and the sample when the probe is brought close to the sample surface to 1 μm or less. A general term for a device that performs two-dimensional mapping of action, including, for example, a scanning tunneling microscope (STM), an atomic force microscope (AFM), a magnetic force microscope (MFM), and a scanning near-field light microscope (SNOM). I have.

[0003] Among them, SNOM is an optical microscope having a resolution exceeding the diffraction limit by detecting near-field light formed near the sample, particularly since the latter half of the 1980s. (Development of various characteristics of dielectric optical waveguides, measurement of emission spectra of semiconductor quantum dots, evaluation of various characteristics of semiconductor surface emitting devices, etc.) are being actively pursued. SNOM
Is a device for detecting a state of a light field (near field) near a sample by bringing a sharp probe close to the sample while irradiating the sample with light.

[0004] US Patent 5,272, issued December 21, 1993 to Betzig et al.
No. 330 introduces light into a probe whose tip is thinned to generate a localized field of light near a small aperture at the tip of the probe, which is brought into contact with the sample to illuminate a small portion of the sample. Discloses an SNOM that detects transmitted light with a photodetector arranged below a sample and performs two-dimensional mapping of transmitted light intensity.

In this SNOM, a rod-shaped probe is used, such as an optical fiber, a glass rod, or a quartz probe whose tip is thinned. As an improved version of this probe, a rod-shaped probe having a portion other than the tip covered with a metal film is already commercially available. The device using this probe has improved lateral resolution compared to a device using a probe that is not coated with metal.

[0006] On the other hand, the AFM is the most widely used device among SPMs as a device for obtaining unevenness information on a sample surface. AF
M detects the displacement of the cantilever, which is displaced in accordance with the force acting on the probe when the probe supported on the tip of the cantilever approaches the sample surface, for example, by an optical displacement sensor, and indirectly detects the sample. Obtain surface irregularity information. One of the AFMs is disclosed in, for example, JP-A-62-130302.

The technique of measuring the unevenness of the sample by detecting the interaction force between the sample and the tip of the probe in this AFM is also applied to other SPM devices, and keeps the distance between the sample and the probe constant. This is used as a means for performing so-called regulation.

[0008] NF van Hulst et a
l.) uses a silicon nitride AFM cantilever in “Appl. Phys. Lett. 62 (5) P.461 (1993)”
A new SNOM that detects optical information of a sample while measuring unevenness of the sample by AFM measurement has been proposed. In this device, the sample is placed on a total internal reflection prism and H
The sample is irradiated with the e-Ne laser beam from the total reflection prism side to excite the sample, and an evanescent light field is formed near the sample surface. Next, a probe supported at the tip of the cantilever is inserted into the evanescent light field, and the evanescent light, which is a localized wave, is converted into scattered light, which is a propagating wave. The light propagates through the almost transparent silicon nitride probe and exits behind the cantilever. This light is collected by a lens placed above the cantilever, enters the photomultiplier via a pinhole located at a position conjugate to the tip of the probe with respect to this lens, and is emitted from the photomultiplier. SNO
An M signal is output.

During the detection of the SNOM signal, the displacement of the cantilever is measured by an optical displacement detection sensor in the same manner as in a normal AFM measurement.
The piezoelectric scanner is feedback-controlled so as to keep this displacement at a specified constant value. Therefore, during one scan, the SNOM is determined based on the scan signal and the SNOM signal.
The measurement is performed, and the AFM measurement is performed based on the scanning signal and the feedback control signal.

In an aperture-type SNOM such as Betzig et al., It is desirable that the probe be metal-coated in order to obtain a high lateral resolution of an image.
However, it is not easy to mass-produce a metal-coated probe having an opening at the tip in a large amount and uniformly.
The SNOM, which is expected to have super-resolution, is required to have a resolution exceeding the resolution achievable with a normal optical microscope. To achieve this, the diameter of the opening at the tip of the probe is 0.1 μm.
Or less, and preferably 0.05 μm or less. It is extremely difficult to produce such an opening with good reproducibility.

Further, the amount of light incident on the probe through the aperture decreases in proportion to the square of the aperture radius.
If the aperture diameter is reduced for the purpose of increasing the lateral resolution of the SNOM image, there is a trade-off problem that the amount of light detected decreases and the S / N ratio of the detection system deteriorates.

In view of this, a new SNOM (scattering mode SNOM) has been proposed which utilizes the fact that a high-refractive-index dielectric or metal having a subwavelength structure strongly scatters near-field light instead of forming an opening at the tip of the probe. I have. In this SNOM, an opening is not required at the tip of the probe, so that it is not necessary to face the above-described difficulty in making the opening and the problem of trade-off.

Have disclosed a scattering mode SNOM in Japanese Patent Application Laid-Open No. Hei 6-137847. This SNO
M scatters the evanescent light formed on the surface of the sample with a needle-shaped probe and converts the scattered light into propagating light. The propagating light, that is, the scattered light, is collected using a condenser lens and a photoelectric detector arranged on the side of the probe. The optical information of the sample is obtained based on the detection signal.

[0014] Kawata et al. Further described the 42nd Japan Applied Physics-related Lecture Meeting (Preprints No. 3, p. 916, 1995).
(Early March) using an STM metal probe as a probe and controlling the distance between the sample and the probe using the STM while evanescent light generated on the sample surface was scattered at the tip of the metal probe. This discloses an apparatus that can observe STM observation and SNOM observation by observing the propagating light from the side of the probe and the sample. The 43rd Japan Applied Physics Alliance Lecture Meeting (Preprints No. 3, p. 887, 1996)
(March) reported that SNOM observation can be performed not only with evanescent light but also with multiple scattering between the tip of the metal probe and the sample of propagating light obliquely incident from above the sample.

Also, Bachelot et al.
Also, in Opt. Lett. 20 (1995) P.1924, a scattering mode SNOM due to light propagating from above without using an aperture probe is reported.

Also, Toda et al., In Japanese Patent Application No. 8-141,752.
Discloses a scattering mode SNOM using a dark field illumination system using a microcantilever for AFM.

[0017]

The probe for the scattering mode SNOM has a structure that becomes thicker from the tip to the base supporting the tip. Further, the light is scattered by a portion within a range of about one wavelength from the tip of the probe. For this reason, the light is scattered not only by the tip of the probe but also by a portion thicker than the tip. The signal due to the scattered light from the thick part reduces the high resolution of the SNOM image.

Sugiura et al., “Opt.
Lett. 22 (1997) p. 1663 "discloses an SNOM that uses gold microspheres supported by a laser trap as a scattering probe. In this SNOM, there is no concern as described above, but imaging takes a very long time because the holding power of the gold microspheres is weak. In addition, the sample that can be observed is limited due to the underwater operation.

An object of the present invention is to minimize the influence of scattered light from other than the tip of the probe, and therefore to achieve a high-resolution SNOM.
The object is to provide an SNOM operable in air that can obtain an image.

[0020]

According to the present invention, there is provided, on one side, an incidence means for making light incident on a sample surface, a probe having a tip arranged at a position close to the sample surface on which the light is incident, and Light detection means for detecting light scattered by the needle,
In the near-field light microscope including a scanning unit that relatively scans the sample and the tip of the probe, the tip of the probe is a tip of an extension that extends in one direction from the probe body. The distal end side of the extension portion has a maximum thickness of not more than three times the distal end diameter over a length equal to or longer than the wavelength of the incident light. The apparatus further comprises means for vibrating in the length direction of the extension.

According to another aspect of the present invention, there is provided a probe for use in a near-field optical microscope, the probe having an extension extending in one direction from a main body of the probe, and a tip of the extension. The side is characterized in that the thickness is at most 3 times the diameter of the tip over a length of 700 nm or more from the tip.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A scattering mode near-field optical microscope according to an embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the scattering mode near-field light microscope has a transparent silicon nitride cantilever tip 100, which is arranged above the sample 1.

As shown in FIG. 2, the cantilever tip 100 has a support portion 103, a cantilever 101 extending from the support portion 103, and a probe 106 provided at the tip of the cantilever 101. This probe 106
Has a needle-like extension 107 extending in a direction substantially perpendicular to the surface of the cantilever 101, and a metal coat 108 is provided at the tip thereof.

FIG. 1 shows a configuration using a tetrapod-shaped ZnO whisker, which is an example of the probe 106, but the tip need not be a tetrapod-shaped as long as it has a sharp structure as shown below. For example, the probe 106 may be a carbon nanotube or a structure sharpened by etching or the like.

If the extension 107 itself is a material or a metal having a high refractive index, the metal coat 108 may not be provided. The extension 107 has a maximum thickness of up to three times the diameter of the tip over a length equal to or longer than the wavelength of the incident light from the tip thereof, including the metal coat 108, if any.

Further, it is preferable that the extension 107 of the probe 106 has a substantially constant thickness from the vicinity of its tip to a portion having a wavelength or more or an irradiation range. Or, the probe 106
Metal coating 10 provided at the tip of extension 107
The objective can be achieved even if the length of the length 8 is sufficiently smaller than the wavelength of the incident light. The reason will be described in detail later.

The back surface of the cantilever 101 (the surface opposite to the surface on which the probe 106 is provided) is coated with an aluminum film 104 as a highly reflective film. If the portion of the cantilever 101 near the probe 106 is transparent, the scattered light generated by the probe 106 is preferably detected without interruption, particularly in a configuration in which the scattered light detection optical system is disposed above the cantilever 101. It is.

As shown in FIG. 1, the cantilever tip 100 is supported above the sample 1 by the tip holding mechanism 35 via the ultrasonic vibrator 795. The cantilever chip 100 is vibrated at the frequency of the high-frequency power supply 796 by an ultrasonic vibrator serving as light amplitude modulation means and a high-frequency power supply 796 for driving the same.

This device has an optical lever type displacement sensor for detecting the displacement of the free end of the cantilever 101.
This displacement sensor has a semiconductor laser 7 for irradiating the cantilever 101 with light, and a two-segment photodetector 8 for receiving reflected light from the cantilever 101. The laser light emitted from the semiconductor laser 7 is applied to the cantilever 101, reflected by the aluminum film 104 provided on the back surface of the cantilever, and enters the two-part photodetector 8. The displacement of the free end of the cantilever 101 causes a change in the incident position of the reflected light on the two-segmented photodetector 8, and changes the output ratio of the light receiving unit of the two-segmented photodetector 8. Therefore, the displacement of the free end of the cantilever 101 is determined by examining the difference between the outputs of the respective light receiving sections of the two-piece photodetector 8, and the displacement of the probe 106 is indirectly determined.

A sample table 401 is fixed to the upper end of the piezoelectric tube scanner 6.
The internal total reflection prism 3 is disposed in the internal space of the first embodiment. The internal total reflection prism 3 is supported independently of the sample table 401, and is exposed from an opening provided at the center of the upper surface of the sample table 401.

The slide glass 2 on which the sample 1 is placed is
An appropriate amount of the matching oil 4 is dropped on the upper surface of the total internal reflection prism 3 and placed on the sample table 401. As a result, as shown in FIG. 1, the matching oil 4 is interposed between the slide glass 2 and the total internal reflection prism 3, and both are optically coupled.

The piezoelectric tube scanner 6 is disposed on the coarse movement stage 345. The coarse movement stage 345
Driven by the coarse movement stage drive circuit 346 controlled by the computer 11, the sample table 401 fixed to the piezoelectric tube scanner 6, that is, the sample 1 placed thereon is coarsely moved three-dimensionally. Thus, rough alignment between the sample 1 and the tip of the extension 107 of the probe 106 is performed, and the sample 1 and the probe 10
The distance between the distal ends of the six extension portions 107 is roughly adjusted.

The piezoelectric tube scanner 6 includes a control circuit 9
And the scanner drive circuit 10 controlled by the computer 11 to move the sample table 401 three-dimensionally. As a result, the sample 1 on the slide glass 2 placed on the sample table 401 is
6 is moved three-dimensionally relative to the tip of the extension 107. As a result, the tip of the extension portion 107 of the probe 106 is scanned across the surface of the sample 1, and
The distance between the tip of the probe 106 and the surface of the tip of the extension 107 of the probe 106 is finely adjusted. In this specification, the scanning of the probe crossing the sample surface is also referred to as XY scanning, and the adjustment of the distance between the tip of the probe and the sample surface is also referred to as Z control. As previously mentioned,
Since the total internal reflection prism 3 is supported independently of the sample table 401, the total internal reflection prism 3 is maintained during scanning.
Is kept immobile without being affected by the movement of the sample table 401.

This apparatus is provided with light generating means for generating light between the probe and the sample. The light generation means has localized light generation means for generating localized light that does not propagate, and propagation light generation means for generating propagation light that generates light to be propagated. Depending on various properties such as pod physical properties,
Either one is selectively operated. Here, the localized light means light that does not propagate in space, for example, evanescent light. Propagating light means light that propagates in space, for example, normal light. Hereinafter, the localized light generating means and the propagated light generating means will be described in detail.

In this case, the evanescent light generating means is a laser light source 13, a filter 14, a lens 15, two mirrors 16 and 17,
It has an internal total reflection prism 3. Laser light source 13
For example, an argon laser having an output of 25 mW is used. The mirror 17 is supported so that its posture (position and direction) can be changed by a moving and rotating mechanism (not shown).
Here, it is arranged in the posture shown in FIG.

The laser light emitted from the laser light source 13 is converted into a parallel beam by the lens 15 after passing through the filter 14. The parallel laser beam is reflected by the mirror 16 and the mirror 17 in order, and then is totally reflected by the internal total reflection prism 3 on the upper surface thereof (that is, at the interface between the slide glass 2 and the sample 1 or the interface between the sample 1 and the atmosphere). .
As a result, evanescent light is generated near the surface of the sample 1. If necessary, a lens for converging a parallel laser beam may be inserted between the mirror 17 and the total internal reflection prism 3. Also, on the optical path of the parallel laser beam,
The half-wave plate 706 may be rotatably arranged. The rotation of the half-wave plate 706 changes the polarization direction of the parallel laser beam.

Further, the propagating light generating means is shown in FIGS.
1 has a laser light source 13, a filter 14, a lens 15, two mirrors 16 and 17, and a lens 18. As described above, the mirror 17 is supported so that its posture (position and direction) can be changed by a moving / rotating mechanism (not shown), and is arranged in the posture shown in FIG. 4 here.

The laser light emitted from the laser light source 13 is converted into a parallel beam by the lens 15 after passing through the filter 14. The parallel laser beam is reflected by the mirror 16 and the mirror 17 in order, and irradiates the sample 1 and the vicinity of the tip of the extension portion 107 of the probe 106 from obliquely above the sample 1 as shown in FIG. In particular, the collimated laser beam is focused by the lens 18 and the probe 10
Irradiation is performed on the tip of the extension portion 107 of FIG. The propagating light generating means may have an optical system using a dark field illumination system as disclosed in Japanese Patent Application No. Hei 8-141752.

As shown in FIG. 1, an objective lens 19 is arranged above the total internal reflection prism 3 with the sample 1 and the probe 106 interposed therebetween. A scattered light detection lens barrel 222 is disposed above the objective lens 19, and the scattered light detection lens barrel 222 forms a scattered light detection optical system in cooperation with the objective lens 19. The scattered light detection optical system detects scattered light generated when the probe enters evanescent light, which is localized light.

The scattered light detection lens barrel 222 includes a lens group 20,
It has a pinhole 21 and a photomultiplier tube 22. The pinhole 21 is disposed at a position optically conjugate with the tip of the extension 107 of the probe 106 with respect to the objective lens 19 and the lens group 20, and the scattered light detection optical system is different from the confocal optical system. Has become. Therefore, most of the light incident on the photomultiplier tube 22 is scattered light generated near the tip of the extension 107 of the probe 106. As described above, the scattered light detection optical system is a confocal optical system.
07 scattered light generated near the tip is efficiently detected. The photomultiplier tube 22 outputs an electric signal corresponding to the light intensity of the received scattered light. In the output signal from the photomultiplier tube 22, a component synchronized with the vibration of the cantilever or a harmonic component thereof, which will be described later, is selectively received and amplified by the lock-in amplifier 24, and is converted into a SNOM signal (near-field signal) by the computer 11. It is taken in. Further, as shown in FIG. 6, reference light having a frequency different from the incident light by δ is introduced into the photomultiplier tube 22 and caused to interfere with each other.
Sum or frequency with cantilever frequency ω1 | ω1 ± δ
A heterodyne detection method for selectively amplifying components can also be used.

This device has a microscope eyepiece tube 28 and a microscope illumination lens tube 25, both of which are optically coupled to the objective lens 19 by a half mirror prism 30 arranged above the objective lens 19. Yes, microscope eyepiece tube 2
Numeral 8 cooperates with the objective lens 19 to form an optical microscope, and a microscope illumination lens barrel 25 cooperates with the objective lens 19 to form an illumination optical system. The optical microscope is used for various optical observations of the sample 1, in addition to specifying an observation point of the sample 1, aligning the tip of the extension 107 of the probe 106 with the observation point,
It is used for confirming the irradiation position of the laser beam of the displacement sensor to the cantilever 101. If you can identify the observation place and confirm the irradiation position of the laser beam for the displacement sensor,
Other means such as a stereo microscope, a loupe, an electron microscope, and the like may be used.

The microscope eyepiece tube 28 is provided with a CCD camera 32 for acquiring an image.
The image acquired by the camera 32 is displayed on the monitor television 34. The microscope illumination lens barrel 25 is connected to an illumination light source 27.

The illumination light emitted from the illumination light source 27 includes a microscope illumination lens barrel 25, a lens 31, and a half mirror prism 3.
0, the sample 1 is irradiated via the objective lens 19.
The light from the sample 1 is supplied to the objective lens 19, the half mirror prism 30, the lens 31, the half mirror prism 370,
Through the mirror prism 371, the eyepiece microscope lens barrel 28
And is imaged on the light receiving surface of the CCD camera 32. C
The image acquired by the CD camera 32 is displayed on the monitor television 34.

In this apparatus, the AFM is simultaneously performed with the SNOM measurement.
A measurement is made. In other words, SNOM during one scan
Information acquisition and AFM information acquisition are performed. The AFM measurement is performed, for example, in a dynamic mode in which a micro vibration is applied to the cantilever so that the probe vibrates in a direction perpendicular to the sample surface.

In this dynamic mode, the tip of the extension 107 of the probe 106 provided at the tip of the cantilever 101 is fixed in a direction substantially perpendicular to the surface of the sample 1 using the ultrasonic vibrator 795. The cantilever tip 100 is vibrated so as to vibrate at the amplitude. When the tip of the extension 107 of the probe 106 is sufficiently close to the surface of the sample 1 (that is, up to the distance where the atomic force acts), the probe 10
The vibration amplitude at the tip of the extension 107 of FIG. While the Z control (that is, the distance between the probe and the sample) is maintained so that the vibration amplitude of the tip of the extended portion 107 of the probe 106 is kept constant, the tip of the extended portion 107 of the probe 106 is XY.
Scanned.

While the tip of the extension 107 of the probe 106 scans across the surface of the sample, Z control between the tip of the probe and the surface of the sample is performed. In the Z control, the control circuit 9 generates a control signal relating to the position in the Z direction in accordance with a signal from the displacement sensor, and based on this, generates a control signal for the scanner driving circuit 10.
The control is performed by controlling the piezoelectric tube scanner 6. During scanning, a control signal generated from the control circuit 9 for Z control is taken into the computer 11 as AFM information, and processed together with an XY scanning signal generated therein. As a result, an AFM image expressing irregularities on the sample surface is formed. During scanning, an output signal from the photomultiplier tube 22 is taken into the computer 11 as SNOM information (near-field information), and processed together with an XY scanning signal generated therein. This allows
An SNOM image expressing optical information on the sample surface is formed. The AFM image and the SNOM image are displayed together on the monitor 12.

In the near-field optical microscope described above, a suitable probe shape will be described. In the above-mentioned near-field microscope, the extension part vibrates up and down as shown in FIG.
The irradiation range of the incident light is not limited to the range of the vibration, but is applied to the extended portion above the range of the vibration. At this time, the extension may be rod-shaped as shown in FIG. 5, but if the extension is a conical shape with the apex facing downward, the light scattered by the conical slope along the top and bottom of the extension is increased. The amount fluctuates, which becomes a noise component and hinders observation.

In order to prevent the generation of this noise as much as possible, it is desirable to make the shape of the extension part close to a rod. That is, it is more preferable that the portion from the vicinity of the tip to the irradiation range has a substantially constant thickness. In this configuration,
In the vertical vibration of the extension portion 107 of the probe 106, there is no difference in the width of the irradiation range other than the portion shown by the broken line in FIG.

Since scattering occurs in a region of about a wavelength from the tip, the thickness may be substantially constant in a portion of about the wavelength. In this case, the S / N can be improved by reducing the pinhole diameter and selecting only the signal from the vicinity of the tip.

However, even if the extension is not substantially constant in thickness, a probe that can be manufactured more easily can be used in practice.
The shape of the extension of the probe may be at least three times the diameter of the tip from the tip of the extension at least over the wavelength of the incident light. Under such conditions, a probe with good noise reduction can be easily manufactured. Although it is difficult to manufacture the probe, more suitable performance can be obtained if the thickness is at most equal to or larger than twice the tip diameter over the length of at least the wavelength of the incident light from the tip of the extension. .

Here, the tip diameter is defined as follows. In other words, it is assumed that a cone whose cross section is a triangle having a vertex angle of 90 degrees is virtually considered, the vertex of the virtual cone is directed downward, and the vertex of the virtual cone coincides with the vertex of the tip of the probe pointing directly downward. . At this time, the intersection of the inclined surface of the virtual cone and the surface of the probe forms a closed curve such as a substantially circular shape, and the tip diameter is defined as twice the average distance from the center of gravity of the closed curve.

Assuming that a typical wavelength of the incident light is, for example, 488 nm light of an argon laser, is adopted as the incident light. The condition that the thickness is maximum and within 3 times the tip diameter is 488 nm on the tip side of the extension.
It can be said that the maximum thickness is within three times the tip diameter over the above length. When 633 nm light of a helium neon laser is used, the condition is that the length is 633 nm from the tip. Furthermore, considering the case where various incident lights are used, considering the wavelength range of the incident light, the condition that the thickness is at most the maximum and within three times the diameter of the tip over a length of 700 nm or more from the tip. Is satisfied, a wide range of incident light types can be handled.

As a method of manufacturing such an extended portion, for example, when an extended portion is manufactured using a tetrapot-shaped ZnO whisker, the growth process of the whisker is stopped on the way, and Should not be sharpened on purpose. In addition, although there is a problem of yield, it is also possible to make the tip of the extension part having a sharp tip come into contact with another object to cut the tip.

However, noise is still unavoidable.
When the irradiation range is larger than the wavelength, it is preferable that the structure has a smoothly changing structure without any scattering source in consideration of S / N. Most desirable is a probe with a smooth structure that has almost the same diameter as the tip diameter in the irradiation range, and the tip of the extension extends over the length of at least the wavelength of the incident light and has the maximum thickness. The probe has a smooth structure within 3 times the tip diameter.

As a signal detection method, there is the lock-in detection described above. In the lock-in detection, only a scattered signal from a broken line portion in FIG. 5 is selectively extracted, so that a high-resolution SNOM image can be obtained. Can be

However, in the lock-in detection method, a cross term between a signal or other noise component from the upper part of the probe and a scattered signal at the tip of the probe due to detection of light intensity on the photomultiplier tube. The disadvantage remains that it cannot be removed. As disclosed in Japanese Patent Application Laid-Open No. H10-170522, the use of the heterodyne detection method eliminates the drawbacks and improves the S / N.

The object is achieved even if the length of the metal coat 108 provided at the tip of the extension 107 of the probe 106 is sufficiently smaller than the wavelength. For example, the length of the metal coat 108 may be 50 nm or less. This is because the scattering efficiency of metal is high, so paying attention to this part,
This is because it is considered as if the metal fine particles are vibrating, and the influence of the remaining extension is reduced. A configuration in which gold fine particles adhere to the tip of the extension portion 107 instead of the metal coat may be used. The diameter of the gold particles in this case is 5
0 nm or less is desirable. The scattering efficiency of the metal coat 108 is much higher if the extension is a material having a relatively low refractive index, so that the metal coat can be regarded as a single metal microsphere having substantially no support. . By vibrating the extending portion 107 of the probe 106 in a direction substantially perpendicular to the sample surface and extracting a component synchronized with the frequency, a high-resolution SNOM image can be obtained. This is supported by the calculation results presented by H. Sasaki et al. In “J. Appl. Phys. 85 (1999) pp. 2026-2030”. Further, the extension 107
By immersing the vicinity in a liquid having a refractive index similar to that of the extension portion, the condition becomes much closer to the condition of the above-mentioned paper, and a high-resolution SNOM image can be obtained.

The present invention is not limited to the above-described embodiment, but includes all implementations that do not depart from the gist of the invention.

The scanning near-field optical microscope according to the present invention can be described as follows.

Supplementary Note 1 Incident means for making light incident on the sample surface, a probe whose tip is arranged at a position close to the sample surface on which the light enters,
In a near-field optical microscope comprising a light detecting means for detecting light scattered by the probe, and a scanning means for relatively scanning the sample and the tip of the probe, the tip of the probe is connected to the probe. The distal end of the extending portion extending in one direction from the needle main body, and the distal end side of the extending portion has a substantially constant thickness over a length equal to or longer than the wavelength of the incident light. The near-field light microscope further comprising means for vibrating the probe in the length direction of the extension part.

Supplementary Note 2 Incident means for making light incident on the sample surface, a probe whose tip is arranged at a position close to the sample surface on which the light enters,
In a near-field optical microscope comprising a light detecting means for detecting light scattered by the probe, and a scanning means for relatively scanning the sample and the tip of the probe, the tip of the probe is connected to the probe. The distal end of the extending portion extending in one direction from the needle main body, and the distal end side of the extending portion has a maximum thickness of 2 mm of the distal end diameter over the length of the wavelength of the incident light or more. The near-field light microscope, wherein the near-field light microscope further comprises means for vibrating the probe in the length direction of the extension.

Supplementary Note 3 Incident means for making light incident on the sample surface, a probe whose tip is arranged at a position close to the sample surface on which the light enters,
In a near-field optical microscope comprising a light detecting means for detecting light scattered by the probe, and a scanning means for relatively scanning the sample and the tip of the probe, the tip of the probe is connected to the probe. The tip of the extension that extends in one direction from the needle main body, and the tip side of the extension is substantially constant in thickness over the irradiation range of the incident light, and the near-field light microscope Is a near-field light microscope, further comprising means for vibrating the probe in the length direction of the extension.

(Supplementary Note 4) Incident means for making light incident on the sample surface, a probe whose tip is located close to the sample surface on which the light is incident,
In a near-field optical microscope comprising a light detecting means for detecting light scattered by the probe, and a scanning means for relatively scanning the sample and the tip of the probe, the tip of the probe is connected to the probe. The tip of the extension that extends in one direction from the needle body, and the tip side of the extension has a maximum thickness of up to twice the tip diameter over the range of irradiation of the incident light. Yes,
The near-field light microscope further comprises means for vibrating the probe in a length direction of the extension part.

(Supplementary Note 5) An incidence means for making light incident on the sample surface, a probe whose tip is arranged in a position close to the sample surface on which the light enters,
In a near-field optical microscope comprising a light detecting means for detecting light scattered by the probe, and a scanning means for relatively scanning the sample and the tip of the probe, the tip of the probe is connected to the probe. The tip of the extension that extends in one direction from the needle body, and the tip of the extension has a maximum thickness of up to three times the tip diameter over the range of irradiation of the incident light. Yes,
The near-field light microscope further comprises means for vibrating the probe in a length direction of the extension part.

(Supplementary Note 6) An incidence means for making light incident on the sample surface, a probe having a tip arranged at a position close to the sample surface on which the light enters,
In a near-field optical microscope comprising a light detecting means for detecting light scattered by the probe, and a scanning means for relatively scanning the sample and the tip of the probe, the tip of the probe is connected to the probe. A tip of an extension extending in one direction from the needle body, wherein the tip side of the extension has a thickness substantially constant over a length of 700 nm or more from the tip, and the near-field light The near-field optical microscope, further comprising: a means for vibrating the probe in a length direction of the extending portion.

(Supplementary Note 7) An incidence means for making light incident on the sample surface, a probe whose tip is arranged close to the sample surface on which the light enters,
In a near-field optical microscope comprising a light detecting means for detecting light scattered by the probe, and a scanning means for relatively scanning the sample and the tip of the probe, the tip of the probe is connected to the probe. The tip of the extension that extends in one direction from the needle body, and the tip side of the extension has a maximum thickness of up to 700 nm or more from the tip and is no more than twice the tip diameter. Wherein the near-field light microscope further comprises means for vibrating the probe in the length direction of the extension.

(Supplementary Note 8) Incident means for making light incident on the sample surface, a probe whose tip is located close to the sample surface on which the light is incident,
In a near-field optical microscope comprising a light detecting means for detecting light scattered by the probe, and a scanning means for relatively scanning the sample and the tip of the probe, the tip of the probe is connected to the probe. The tip of the extension that extends in one direction from the needle body, and the tip side of the extension is 700 nm or more from the tip and has a maximum thickness of up to three times the tip diameter. Wherein the near-field light microscope further comprises means for vibrating the probe in the length direction of the extension.

(Supplementary Note 9) A metal film is applied to the tip of the extension part over a length of 50 nm or less from the tip.
The near-field light microscope according to claim 1 or any one of supplementary notes 1 to 8.

[Supplementary note 10] The proximity according to any one of Supplementary notes 1 to 8, wherein a metal sphere having a diameter of 50 nm or less is attached to the tip of the extension portion. Field light microscope.

(Supplementary Note 11) The apparatus according to any one of Supplementary Notes 1 to 8, further comprising signal processing means for processing an output of the light detection means using heterodyne detection. Near-field light microscope.

(Supplementary Note 12) An incident means for making light incident on the sample surface, a probe whose tip is arranged in a position close to the sample surface on which the light enters,
In a near-field optical microscope comprising a light detecting means for detecting light scattered by the probe, and a scanning means for relatively scanning the sample and the tip of the probe, the tip of the probe is connected to the probe. Means for vibrating the probe in the length direction of the extension portion, the extension portion extending in one direction from the needle body, and the extension portion filling the space between the tip of the probe and the sample. A near-field optical microscope, further comprising a liquid having a refractive index substantially equal to that of the projection.

Supplementary Note 13 A probe used for a near-field microscope, which has an extending portion extending in one direction from a main body of the probe, and a tip side of the extending portion is 700 nm or more from the tip. A probe for a near-field optical microscope device, wherein the thickness is substantially constant over the length.

Supplementary Note 14 A probe used in a near-field microscope, which has an extension extending in one direction from the main body of the probe, and a tip side of the extension is 700 nm or more from the tip. A probe for a near-field optical microscope device characterized in that the thickness is at most twice the tip diameter over the length.

(Supplementary note 15) The one of Supplementary note 13 or Supplementary note 14, wherein a metal film is applied to the tip end side of the extension portion over a length of 50 nm or less from the tip end. Item 12. The probe for a near-field light microscope device according to item 9.

(Supplementary note 16) The near field according to any one of Supplementary note 13 or Supplementary note 14, wherein a metal sphere having a diameter of 50 nm or less is attached to a tip of the extension. Probe for light microscope equipment

[0077]

According to the present invention, the probe has an extending portion extending in one direction, and the thickness thereof is at most twice the diameter of the tip from the tip over the length of the wavelength of the incident light or more. Within
An SNOM operable in air is provided, in which the influence of scattered light other than from the tip of the probe is minimized. This allows
A high-resolution SNOM image can be obtained.

[Brief description of the drawings]

FIG. 1 schematically shows the entire configuration of a scattering mode scanning near-field light microscope according to the present invention.

FIG. 2 is a perspective view of a cantilever chip used in the scanning near-field light microscope shown in FIG.

FIG. 3 is an enlarged view of a tip portion of an extension of a probe of the cantilever tip shown in FIG. 2;

FIG. 4 shows a state in which a parallel laser beam is applied to a sample from obliquely above as propagating light.

FIG. 5 shows a state in which the extension of the probe vibrates in a direction perpendicular to the sample surface.

FIG. 6 schematically shows the entire configuration of a scattering mode scanning near-field light microscope according to the present invention using the heterodyne detection method.

[Explanation of symbols]

 Reference Signs List 3 total internal reflection prism 6 piezoelectric tube scanner 7 semiconductor laser 8 two-part photodetector 11 computer 13 laser light source 19 objective lens 20 lens group 21 pinhole 22 photomultiplier tube 106 probe 107 extension part 222 scattered light detection lens barrel

Claims (3)

[Claims] 1. An incident means for injecting light into a sample surface, a probe having a tip arranged at a position close to the sample surface on which the light is incident, and a light detector for detecting light scattered by the probe. Means, a near-field optical microscope comprising scanning means for relatively scanning the sample and the tip of the probe, wherein the tip of the probe has an extension portion extending in one direction from the probe body. The tip is a tip, and the tip side of the extension portion has a maximum thickness of not more than three times the tip diameter over a length equal to or longer than the wavelength of the incident light. A near-field optical microscope further comprising means for vibrating a probe in a longitudinal direction of the extension. 2. The near field according to claim 1, wherein a metal coating is applied to the tip of the extension from the tip over a length equal to or less than the wavelength of the incident light. Light microscope. 3. A probe for use in a near-field optical microscope, comprising an extension extending in one direction from a main body of the probe, wherein a tip side of the extension is 700 nm or more from the tip. A tip for a near-field optical microscope device having a maximum thickness of not more than three times the tip diameter over the entire length of the probe.