JP2008102152A - Scanning probe microscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scanning probe microscope capable of more accurately measuring the surface shape or physical properties of a measuring target by making the S/N ratio improved. <P>SOLUTION: The scanning probe microscope 1 is equipped with an observation light-receiving mechanism 30 for condensing and receiving the observation light L3 emitted from the measuring region of the measuring target S that faces the leading end of a cantilever 10 and a displacement detection mechanism 20 for irradiating the cantilever 10 with detection light L1, having a wavelength different from that of the observation light L3, to measure the detection light L1 reflected by the cantilever 10 to detect the displacement of the cantilever 10. The optical path of the detection light L1 and the optical path of the observation light L3 are set so as to pass through a common optical path, at least at a part of them and a dielectric beam splitter (optical filter) 32, having optical characteristics wherein the transmissivity of the observation light L3 is higher than that of the detection light L1 is arranged on the common light. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

Detailed Description of the Invention

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a scanning probe microscope that measures a surface shape or physical properties of a measurement object by relatively moving a cantilever such as a scanning near-field microscope and the measurement object, for example.

Conventional technology

As is well known, various devices are currently known for measuring specimens such as electronic materials, biological samples, semiconductor devices, etc. in a minute region, observing the surface shape of the specimen, measuring local characteristics, etc. ing. As one of them, a scanning probe microscope (SPM) that can measure the unevenness and physical properties of the sample surface with high resolution by using a cantilever with a minute probe at the tip is known. (See, for example, Non-Patent Document 1).

In this scanning probe microscope, a sample holder is provided on a three-axis fine movement mechanism constituted by a cylindrical piezoelectric element, and a sample is mounted on the sample holder. Further, a cantilever having a probe at the tip, which is fixed to the cantilever holder, is disposed above the sample. When the probe is brought close to the sample surface, the cantilever bends due to the atomic force acting between the probe and the sample. The magnitude of this atomic force depends on the distance between the sample and the probe, and increases along the exponential curve as the probe approaches the sample. Therefore, the distance between the sample and the probe is constant (ie,
The distance between the sample and the probe is controlled by a fine movement mechanism so that the amount of bending of the cantilever is constant), and the sample is scanned in a dual plane by the fine movement mechanism. It is possible to obtain

Furthermore, the cantilever holder is provided with an excitation mechanism such as a piezoelectric element, and the cantilever is vibrated in the vicinity of the resonance frequency by the excitation mechanism, while being close to the sample, the atomic force acting between the cantilever and the sample surface or intermittent In some cases, changes in the amplitude and phase of the cantilever due to a typical contact force are detected, and the distance between the sample and the probe is controlled using these parameters.

In this scanning probe microscope, a method using an optical lever type optical displacement detection mechanism is adopted as a method for measuring the displacement amount of the cantilever.
This optical lever type displacement detection mechanism can measure a minute displacement of a cantilever with high sensitivity and is the most commonly used displacement detection mechanism. That is, this optical lever type displacement detection mechanism reflects a laser beam from a light source using a semiconductor laser by a beam splitter and irradiates the back surface of the cantilever. Then, the intensity of the reflected light reflected from the back surface of the cantilever is detected by a photodetector called a position sensitive detector (PSD). Note that the PSD usually uses a semiconductor photodetector having a light receiving surface divided into four parts.

In measuring the displacement amount of the cantilever using the optical lever type displacement detection mechanism, the semiconductor laser is first moved to position the semiconductor laser so that the laser spot hits the back surface of the cantilever. Next, the reflectance at the back of the cantilever is PSD
Move the PSD so that it hits the center of the.

Next, when the sample is measured by scanning the cantilever, if the cantilever bends, the spot moves on the PSD. That is, the spot moves on the detector divided into four. Thereby, it is possible to detect the amount of bending of the cantilever from the output of the difference between the areas of the detector corresponding to the moving direction of the spot. Also,
The torsion amount of the cantilever can also be measured from the output of the difference of each region of the detector, and furthermore, the frictional force when the sample is moved in the cantilever torsion direction can be measured.

An objective lens is disposed above the displacement detection mechanism. This objective lens is used for spot observation when observing a sample surface or aligning a laser spot of a displacement detection mechanism with the back surface of a cantilever. That is, in the optical lever type displacement detection mechanism, it is essential to observe with an objective lens from above the sample. That is, it is necessary to arrange a displacement detection mechanism so as to ensure the optical path of the objective lens. For this purpose, a method of securing the optical path of the objective lens by irradiating the semiconductor laser with respect to the cantilever from an oblique direction and providing a space above the objective lens is conceivable. Because it changes, it is difficult to align the optical axis.

Therefore, normally, as this scanning probe microscope adopts, there is a method in which light from the laser is once blown horizontally, and light is irradiated from directly above by bending by 90 ° with a mirror disposed directly above the cantilever. Used. At this time, the spot can be positioned by moving the laser vertically and horizontally with respect to the mirror. In addition, a beam splitter whose normal transmittance and reflectance are about 50% each is used for the mirror. As a result, the mirror reflects about 50% of the laser light and irradiates the cantilever, and of the incident light from above, about 50% of the illumination light that passes through the beam splitter allows observation of the sample surface and the cantilever and laser. Spot positioning is performed.
Masatake Yasutake, “BASIC RESEARCH OF THE ATOMIC FORCE MICROSCOPE FOR INDUSTRIAL USE”, Tokyo Institute of Technology Doctoral Dissertation, October 1996, P18-74

By the way, in the scanning probe microscope described in Non-Patent Document 1, since it is a beam splitter having a mirror transmittance and reflectance of 50%, as described above, a beam splitter is disposed between the objective lens and the sample. In this case, only 50% of the illumination light for observing the sample surface is transmitted. That is, there is a disadvantage that the observation light necessary for observing the sample cannot be efficiently collected and the S / N ratio is lowered.

The present invention has been made in consideration of such circumstances, and its purpose is S / N.
It is to provide a scanning probe microscope capable of improving the ratio and measuring the surface shape and physical properties of the object to be measured more accurately.

  In order to achieve the above object, the present invention provides the following means.

In the scanning probe microscope of the present invention, a cantilever having a probe at the tip thereof is brought close to or in contact with the surface of the object to be measured, and the cantilever and the object to be measured are moved relative to each other to form the surface shape of the object to be measured. Or a scanning probe microscope that measures physical properties, an observation light receiving mechanism that collects and receives observation light emitted from a measurement region of the measurement object facing the tip of the cantilever, and the observation on the cantilever A displacement detection mechanism that detects detection light reflected from the cantilever by irradiating detection light having a wavelength different from that of the light, and detects the displacement of the cantilever, and the optical path of the detection light and the optical path of the observation light are at least And an optical filter having an optical characteristic in which the transmittance of the observation light is higher than that of the detection light is disposed on the common optical path. And features.

In the scanning probe microscope according to the present invention, an optical filter having an optical characteristic in which the transmittance of the observation light is higher than that of the detection light is disposed on the common optical path.
When passing through the optical filter, more observation light is transmitted than the detection light, and the transmission efficiency of the observation light is improved. Therefore, in the observation light receiving mechanism, the S / N ratio can be improved by receiving the observation light with high efficiency, and the surface shape and physical properties of the object to be measured can be measured more accurately.

The scanning probe microscope of the present invention is the above-described scanning probe microscope of the present invention, wherein the observation light receiving mechanism includes an objective lens that condenses the observation light, and the displacement detection mechanism converts the detection light into the objective light. The optical filter is set to perform the irradiation through a lens, and the optical filter is disposed on the common optical path behind the objective lens with respect to the object to be measured.

In the scanning probe microscope according to the present invention, the optical filter is disposed behind the objective lens, and the displacement detection mechanism can irradiate the detection light through the objective lens. The distance becomes shorter. That is, the working distance (WD) of the objective lens is shortened. Therefore, an objective lens having a large numerical aperture (NA) can be used, and the S / N ratio can be improved.

The scanning probe microscope according to the present invention is the above-described scanning probe microscope according to the present invention, wherein the optical filter is a beam splitter, and the optical path of the detection light and the optical path of the observation light are branched by the beam splitter. It is characterized by being.

In the scanning probe microscope according to the present invention, since the optical path of the detection light and the optical path of the observation light are branched by a beam splitter such as a dielectric beam splitter, the displacement detection mechanism and the observation light receiving mechanism are separately provided. It is possible to dispose them at the positions, and the degree of freedom of arrangement is improved. Therefore, the apparatus can be configured compactly.

The scanning probe microscope according to the present invention is the above-described scanning probe microscope according to the present invention, wherein the beam splitter is arranged directly above the cantilever, and the detection light is irradiated from directly above the cantilever. And

In the scanning probe microscope according to the present invention, since the detection light can be irradiated from directly above the cantilever, the optical axis is aligned without changing the size of the spot of the detection light when positioning the displacement detection mechanism. Becomes easy.

The scanning probe microscope according to the present invention is the scanning probe microscope according to any one of the present invention described above, wherein the displacement detection mechanism is arranged on an optical path of the detection light reflected from the cantilever, and the detection light is A wavelength filter that transmits and cuts the observation light is provided.

In the scanning probe microscope according to the present invention, since the displacement detection mechanism includes the wavelength filter, the observation light included in the light from the cantilever is cut by the wavelength filter, and the light receiving accuracy of the detection light is increased, and the cantilever The displacement can be detected with higher accuracy.

A scanning probe microscope according to the present invention is the scanning probe microscope according to any one of the present inventions described above, further comprising evanescent light generating means for generating evanescent light on the object to be measured.

In the scanning probe microscope according to the present invention, since the object to be measured includes the evanescent light generating means for generating the evanescent light, the observation light generated by the interaction between the evanescent light and the object to be measured is received. Light can be collected and received by the mechanism. Therefore, the measurement object can be measured while improving the S / N ratio with high resolution exceeding the diffraction limit.

The scanning probe microscope of the present invention is the above-mentioned scanning probe microscope of the present invention, wherein the evanescent light generating means has a diameter of 10 formed at the tip of the probe.
An opening of 0 nm or less, and an evanescent light irradiation mechanism for irradiating irradiation light in the opening to generate evanescent light in the vicinity of the opening and irradiating the measurement area with evanescent light. Observation light is condensed at the opening and is incident on the optical filter.

In the scanning probe microscope according to the present invention, the observation light generated by the interaction between the evanescent light and the object to be measured can be condensed from the probe opening close to or in contact with the surface of the object to be measured. The evanescent light can be efficiently irradiated to the object to be measured. Therefore, the collection rate of the observation light is increased and the S / N ratio can be further improved.

The scanning probe microscope of the present invention is the above-described scanning probe microscope of the present invention, wherein at least the tip of the cantilever is formed of a material that can transmit the observation light, and the observation light receiving mechanism is the tip of the cantilever. The observation light transmitted through the part is received.

In the scanning probe microscope according to the present invention, since at least the tip of the cantilever is made of a material that can transmit observation light, it is not necessary to perform opening processing or the like on the tip of the cantilever. Further, the observation light can be efficiently collected by setting the tip shape.

The scanning probe microscope of the present invention is the above-described scanning probe microscope of the present invention, wherein the evanescent light generated on the surface of the object to be measured is scattered at the tip of the cantilever, and the observation light receiving mechanism is at the tip of the cantilever. It is characterized by receiving scattered light.

In the scanning probe microscope according to the present invention, it is possible to collect stronger observation light by depositing a metal thin film having an electric field enhancing effect on the tip of the cantilever.

In the scanning probe microscope of the present invention, the following effects can be obtained. That is, since the optical filter having the optical characteristic that the transmittance of the observation light is higher than that of the detection light is disposed on the common optical path, the transmission efficiency of the observation light is improved. Therefore,
The S / N ratio can be improved by receiving highly efficient observation light, and the surface shape and physical properties of the object to be measured can be measured more accurately.

BEST MODE FOR CARRYING OUT THE INVENTION

A first embodiment according to the present invention will be described below with reference to FIGS.

As shown in FIG. 1, the scanning probe microscope of this embodiment is a scanning near field optical microscope (SNOM) combining a near field microscope capable of measuring the surface of the sample S with high resolution exceeding the diffraction limit. The cantilever 10 and the sample S are placed in a state where the cantilever 10 having the probe 11 at the tip is brought close to the surface of the sample (measurement object) S such as a biological cell stained with fluorescence. The surface shape or physical properties of the sample S are measured by relatively moving.

The scanning near-field microscope 1 includes, for example, a displacement detection mechanism 20 that detects the displacement of the cantilever 10 by irradiating the cantilever 10 with the detection light L1 having a wavelength of 785 nm and measuring the detection light L1 reflected by the cantilever 10. For example, the measurement region of the sample S facing the tip of 10 has, for example, an objective lens 31 that irradiates excitation light L2 with a wavelength of 488 nm and collects and receives observation light L3 including fluorescence with a peak wavelength of 530 nm. Provided with an observation light receiving mechanism 30 and evanescent light generating means 40 for generating evanescent light on the sample S.

The observation light receiving mechanism 30 includes a dielectric beam splitter (optical filter) 32 having optical characteristics in which the transmittance of the observation light L3 is higher than that of the detection light L1. The dielectric beam splitter 32 is disposed at a position where the optical path of the detection light L1 and the optical path of the observation light L3 are at least partially transmitted through the common optical path. That is, the dielectric beam splitter 32 is disposed on the common optical path between the sample S and the objective lens 31 and is located directly above the cantilever 10. As shown in FIG. 2, the dielectric beam splitter 32 has a dielectric multilayer film 3 on the slope of a 45 ° right angle prism.
2a is vapor-deposited and bonded, and an antireflection film is vapor-deposited around it. The dielectric multilayer film 32a has a filter function that allows a specific wavelength to be transmitted with high efficiency. The dielectric multilayer film 32a of the present embodiment has a transmittance of 90% or more for wavelengths in the range of 450 nm to 650 nm, and a reflectance and transmittance ratio of 50% for wavelengths of 785 nm. . Thus, the dielectric beam splitter 32
Transmits the observation light L3 with higher efficiency than the detection light L1, and the detection light L1.
And the optical path of the observation light L3 are branched.

In addition, as shown in FIG.
1, a dichroic mirror 36, an absorption filter 33, an imaging lens 34, and a photodetector 35 are disposed as an observation light receiving mechanism 30. The dichroic mirror 36 and the absorption filter 33 have a function of cutting the excitation light L2 out of the observation light L3 transmitted through the dielectric beam splitter 32 and condensed by the objective lens 31, and causing fluorescence to enter the imaging lens 34. Have. A total reflection mirror 37 is detachably disposed on the rear side of the imaging lens 34. When the total reflection mirror 37 is inserted on the optical path, the light on the optical path is bent and the CCD camera 38 is bent.
And the optical image can be observed. At this time, since the dielectric beam splitter 32 has a transmittance of 50% with respect to the wavelength of the detection light L1, a part of the detection light L1 reflected by the sample S passes through the dielectric beam splitter 32, and the objective beam The light is condensed by the lens 31 and can be observed by the CCD camera 38. As a result, the alignment between the detection light L1 and the cantilever 10 and the alignment between the sample S and the probe 11 are possible.

On the other hand, the observation light L3 containing fluorescence is imaged by the imaging lens 34 and then detected light L3.
The light is transmitted through a short-pass filter 39 that is a filter for cutting 1 and introduced into the photodetector 35. In the present embodiment, the filter has a wavelength of 6
A short pass filter 39 having a characteristic of cutting 50 nm or more and transmitting a wavelength of 650 nm or less was used. When detecting fluorescence, the total reflection mirror 37 is used.
Is withdrawn from the optical path. The photodetector 35 uses an avalanche photodiode having a light receiving surface as small as several hundred μm. In addition, a photomultiplier, a spectroscope, etc. are used as this kind of photodetector.

The displacement detection mechanism 20 includes a detection light emitting unit LD such as a semiconductor laser that irradiates the detection light L1 of the laser light, and a detection light receiving unit PSD that receives and measures the detection light L1 reflected by the cantilever 10. The displacement of the cantilever 10 is detected by an optical lever method. The detection light emitting part LD is horizontally arranged so as to irradiate the detection light L1 horizontally toward the dielectric beam splitter 32. As a result, the detection light L1 emitted from the detection light emitting unit LD is reflected by the dielectric beam splitter 32, changes its direction downward, and can be irradiated onto the cantilever 10 from directly above. The detection light receiving part PSD is a semiconductor photodetector having a light receiving surface divided into four parts, and detects the intensity of the detection light L1 reflected by the cantilever 10. Accordingly, for example, when the cantilever 10 is bent and the beam spot of the detection light L1 moves, each detector among the four-divided detectors measures a difference such as an intensity difference to detect the difference in intensity. It is possible to detect 10 displacement amounts, twist amounts, and the like.

Further, the displacement detection mechanism 20 transmits the detection light L1 and cuts the observation light L3 on the optical path of the detection light L1 reflected from the cantilever 10, for example, 700.
A long-pass filter (wavelength filter) 21 having a wavelength of nm is provided in front of the detection light receiving unit PSD. Accordingly, the detection light receiving unit PSD is prevented from mixing the observation light L3, and the detection light L1 reflected from the cantilever 10 can be received with high efficiency.

The sample S is placed and fixed on a sample holder 51, and the sample holder 51 is disposed on a fine movement mechanism 52 that is a cylindrical piezoelectric element (piezo element). The fine movement mechanism 52 is provided with electrodes uniformly along the circumference, and the sample S
A Z fine movement mechanism 52a for controlling the distance between the cantilever 10 and the cantilever 10, and an XY fine movement mechanism 52b for scanning the sample S in the XY direction in a two-dimensional plane provided with electrodes divided into four on the circumference. have. Further, the fine movement mechanism 52 is connected to the coarse movement mechanism 5 via the XY stage 13 for positioning the sample S and the probe 11.
3 is arranged. The coarse movement mechanism 53 has a function of bringing the sample S closer to the probe 11 of the cantilever 10 by a feed screw method using a drive source such as a stepping motor. Each drive source that drives the above-described Z fine movement mechanism 52a, XY fine movement mechanism 52b, and coarse movement mechanism 53 is comprehensively controlled by the control unit 55.

The cantilever 10 is fixed to a cantilever holder 15, and the cantilever holder 15 has a vibrator 15 a that applies minute vibrations to the cantilever 10.
Is provided. The cantilever holder 15 is an XY stage 1 for aligning the optical axis centers of the cantilever 10 and the objective lens 31 together with the displacement detection mechanism 20.
6 to the base 17. The cantilever 10 is formed of a material such as silicon oxide that can transmit the observation light L3, as shown in FIG.
Aluminum is coated except for the tip of the probe 11. Further, on the back surface of the cantilever, an aluminum reflecting surface 10a that reflects the detection light L1 emitted from the detection light emitting unit LD is provided except for a portion through which the observation light L3 is transmitted. An opening 10b having a diameter of 50 nm is formed. The cantilever 10 configured in this manner functions as a waveguide for the excitation light L2 and the observation light L3.

Further, as shown in FIG. 1, for example, excitation light (irradiation light) L2 having a wavelength of 488 nm.
Excitation light source (evanescent light irradiation mechanism) 41 that irradiates the observation light receiving mechanism 3
0 is arranged. The excitation light source 41 has its optical path bent by the dichroic mirror 36 and optically coupled to the opening 10b of the cantilever by the objective lens 31, so that the excitation light L2 can be irradiated to the opening 10b. Has been. That is, the excitation light source 41 has a function of irradiating the opening 10b with the excitation light L2, generating evanescent light in the vicinity of the opening 10b, and irradiating the measurement region of the sample S with the evanescent light. Further, the observation light L3 generated by the irradiation of the evanescent light is condensed at the opening 10b, and the dielectric beam splitter 3 is collected.
2 is incident. That is, the cantilever 10 having the opening 10b and the excitation light source 41 constitute the evanescent light generating means 40.

A case where the sample S is measured using the scanning near-field microscope 1 configured as described above will be described.

First, the objective lens 31 is focused on the surface of the sample S by the focusing stage 12 provided on the objective lens 31. Next, the probe 11 of the cantilever 10 is positioned at the optical axis center of the objective lens 31 by the XY stage 16.
Then, the displacement detector mechanism 20 is positioned while observing with the objective lens 31. That is, positioning is performed by moving the detection light emitting unit LD so that the laser spot of the detection light L <b> 1 hits the reflection surface 10 a of the cantilever 10. After the detection light emitting unit LD is positioned, the PSD is positioned so that the detection light L1 reflected by the reflecting surface 10a hits the center of the detection light receiving unit PSD. Further, the probe 11 and the sample S are positioned by the XY stage 13.

Next, distance control between the probe 11 and the sample S is performed. That is, while the cantilever 10 is vibrated in the vicinity of the resonance frequency by the vibrator 15a, the coarse movement mechanism 53 is operated while monitoring the attenuation amount of the amplitude when it is brought close to the sample S.

Then, after the sample S is brought close to the probe 11 to a region where the atomic force acts or contacts between the sample S and the probe 11, the Z fine movement mechanism 52a and the sample S are adjusted so that the amplitude becomes constant. Distance control with the probe 11 is performed. That is, the detection light L1 irradiated by the detection light emitting unit LD is reflected by the dielectric beam splitter 32 and hits the reflection surface 10a of the cantilever 10. Then, unnecessary light (for example, observation light described later) is cut by the wavelength filter 21 and the detection light L1 reflected by the reflection surface 10a enters the detection light receiving unit PSD. At this time, the laser spot of the detection light L1 moves on the four detectors of the detection light receiver PSD according to the displacement of the cantilever 10. The distance can be controlled by measuring the difference between the detectors and performing feedback control of the Z slight increase mechanism 52a.

In the state where the distance control is performed, the sample S is measured in the illumination collection mode. That is, the excitation light source 41 emits excitation light L2, and the sample S is irradiated with evanescent light from the opening 10b of the cantilever 10. The observation light L3 of the sample S generated by the evanescent light is condensed again at the opening 10b. At this time, the observation light L3 includes excitation light L2 and fluorescence. Further, the condensed observation light L3 passes through the cantilever 10 and enters the dielectric beam splitter 32. At this time, the dielectric beam splitter 32 is set to have a different transmittance depending on the wavelength and has a characteristic of transmitting the observation light L3 more than the detection light L1, so that the observation light L3 is transmitted with high efficiency. .

Further, the observation light L3 transmitted through the dielectric beam splitter 32 is transmitted through the dichroic mirror 36 having such characteristics that most of the excitation light L2 component is reflected and most of the fluorescence is transmitted. The fluorescent component is selectively transmitted, the excitation light L2 is cut, and only the fluorescence is incident on the imaging lens. This fluorescence is imaged by the imaging lens 34 and detected by the photodetector 35. Thereby, the optical physical properties of the sample S are measured. As described above, the detection light L1
Is also incident on the observation light receiving mechanism 30, but this detection light L1 is cut by a short pass filter 39 disposed in front of the photodetector 35.

In the above measurement, the sample S is scanned by scanning the XY fine movement mechanism 52b.
Surface observation such as a concavo-convex image can be measured simultaneously.

The scanning near-field microscope 1 according to the present embodiment includes the dielectric beam splitter 32 having optical characteristics in which the transmittance of the observation light L3 is higher than that of the detection light L1. The light can be transmitted with high efficiency compared to the light of. As a result, the transmission efficiency of the observation light L3 is increased, and the S / N ratio can be improved.
Therefore, the more accurate surface shape and physical properties of the sample S can be measured.

Further, since the dielectric beam splitter 32 branches the optical path of the detection light L1 and the optical path of the observation light L3, the displacement detection mechanism 20 and the observation light receiving mechanism 40 can be arranged at different positions and can be arranged freely. Since the degree is improved, a compact configuration can be achieved.

In addition, since the dielectric beam splitter 32 is disposed directly above the cantilever 10, when positioning the displacement detection mechanism 20, the optical axis is aligned without changing the spot size of the detection light L1. Is easy.

Further, since the wavelength filter 21 is disposed in front of the detection light receiving unit PSD, the observation light L3 included in the light from the cantilever 10 is cut. Accordingly, the detection light receiving unit PSD can detect the displacement of the cantilever 10 with higher accuracy because the light reception accuracy with respect to the detection light L1 is increased.

Next, a second embodiment according to the present invention will be described with reference to FIGS. In this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

The difference between the second embodiment and the first embodiment is that the sample S is measured in the illumination collection mode in the first embodiment, whereas the scanning near-field microscope 100 in the second embodiment is in the collection mode. This is the point at which the sample S is measured.

That is, as shown in FIG. 4, the evanescent light generating means 140 is, for example, 13
An excitation light source 141 that emits excitation light L2 having a wavelength of 00 nm is provided, and the excitation light source 141 is disposed at a position where the excitation light L2 can be introduced into the sample S via the optical fiber 142. .

The sample S of this embodiment is an optical device in which an optical waveguide that passes 1300 nm is formed, and an optical fiber 142 is optically coupled to the sample S in order to introduce the excitation light L2. Also, the dielectric beam splitter 120
The dielectric multilayer film 120a has a transmittance of 9 for a wavelength of 1300 nm, for example.
For the wavelength of 0% or more and 670 nm, the ratio of reflectance and transmittance is set to 50%. Further, a short-pass filter (wavelength filter) 121 having a wavelength of 750 nm is disposed in front of the detection light receiving unit PSD. Furthermore, the detection light emitting part L
D is set to irradiate the detection light L1 having a wavelength of 670 nm.

Further, the observation light receiving mechanism 130 is an objective lens 1 that can collect 1300 nm light.
31, an imaging lens 134, a total reflection mirror 137 detachably arranged to branch light to the vidicon camera 138 side, a vidicon camera 138 used for detection light observation, and a detection light L 1 mixed in the observation light receiving mechanism 130. And a photodetector 135 such as a photomultiplier tube for measuring light intensity, and a long-pass filter 139 having a threshold value at a wavelength of 800 nm.

When measuring the sample S using the scanning near-field microscope 100 of the present embodiment, excitation light L2 is introduced into the sample S by the excitation light source 141. The introduced excitation light L2 propagates inside the optical waveguide of the sample S. At this time, evanescent light is generated on the surface of the sample S having the optical waveguide S1 as shown in FIG. By observing this evanescent light component, the optical waveguide can be evaluated.

The evanescent light is scattered as observation light L <b> 3 around by the interaction between the sample S and the probe 11. Further, part of the observation light L3 is the opening 10b of the probe 11.
And then passes through the dielectric beam splitter 120, the imaging lens 134 and the long pass filter 139 and is detected by the photodetector 135. At this time, in the dielectric beam splitter 120, the observation light L 3 is transmitted with a transmittance of 90% or more and transmitted to the photodetector 35.

As described above, according to the scanning near-field microscope 100 of the present embodiment, the observation light L3 can be incident on the photodetector 35 with high efficiency by the dielectric beam splitter 120. The ratio of the sample S can be improved.

Next, a third embodiment according to the present invention will be described with reference to FIGS. In this embodiment, the same components as those in the first embodiment and the second embodiment are denoted by the same reference numerals, and the description thereof is omitted.

The difference between the third embodiment and the first embodiment is that the sample S is measured in the illumination collection mode in the first embodiment, whereas the scanning near-field microscope 200 in the third embodiment is different in the scattering mode. This is a point where the near field spectroscopic analysis of the sample S is performed. That is, the sample S of this embodiment is a polymer sample,
The Raman scattered light when irradiated with the excitation light L2 is collected by the observation light receiving mechanism 230 and subjected to spectroscopic analysis to perform structural analysis of the polymer sample.

In the present embodiment, as shown in FIG. 6, the evanescent light generation means 240 includes, for example, an excitation light source 241 that irradiates excitation light L2 having a wavelength of 488 nm, and the excitation light source 241 is applied to the sample S. On the other hand, it is arranged at a position where the excitation light L2 can be irradiated obliquely from above.

The dielectric multilayer film 220a of the dielectric beam splitter 220 has, for example, a transmittance of 90% or more for the target Raman scattered light, and a reflectance and transmittance ratio of 50% for the wavelength of 785 nm. Is set to In the present embodiment, 4
A transmittance of 90% or more can be secured in the range of 50 nm to 650 nm. Further, a long-pass filter (wavelength filter) 221 having a wavelength of 700 nm is disposed in front of the detection light receiving unit PSD. Furthermore, the detection light emitting part LD is 78
The detection light L1 having a wavelength of 5 nm is set to be irradiated.

When the measurement of the sample S is performed using the scanning near-field microscope 200 of the present embodiment, the excitation light L2 is obliquely upwardly directed toward the surface of the sample S by the excitation light source 241.
Irradiate. By the irradiated excitation light L2, evanescent light is generated on the surface of the sample S as shown in FIG.

The cantilever 210 has a shape in which the probe 211 protrudes from the cantilever part 210a to the tip, and the tip part 211a of the probe is the cantilever part 210a.
It is possible to observe with the objective lens 31 without being interrupted.

The evanescent light is scattered around as the observation light L3 due to the interaction between the sample S and the probe tip 211a. At this time, for the purpose of improving the scattering efficiency, a silver thin film is deposited on the probe tip 211a. The observation light L3 passes through the dielectric beam splitter 220, is condensed by the objective lens 31, and is guided to the spectroscope 235 through the imaging lens. At this time, in the dielectric beam splitter 220, the observation light L3 is transmitted with a transmittance of 90% or more and transmitted to the spectroscope 235. A notch filter 239 for cutting the detection light L1 and a notch filter 236 for cutting the excitation light L2 are inserted in front of the spectroscope 235.

As described above, according to the scanning near-field microscope 200 of the present embodiment, the observation light L3 can be incident on the spectroscope 235 with high efficiency by the dielectric beam splitter 220. Thus, the sample S can be measured.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, in each of the above embodiments, the dielectric beam splitter 3 is used as the optical filter.
2, 120, and 220 are used, but the present invention is not limited to this, and any optical filter may be used as long as the transmittance of the wavelength of the observation light L3 is higher than that of the detection light L1. For example,
A metal film deposited on a beam splitter, a gelatin filter deposited, or a colored glass may be used. Further, the substrate need not be a beam splitter, and for example, a parallel plane substrate may be disposed obliquely.

Further, the dielectric beam splitters 32, 120, and 220 are the objective lenses 31, 1 and 2, respectively.
31 and the sample S, the optical path of the observation light L3 and the detection light L
It suffices if they are arranged on a common optical path that is at least partially in common with one optical path.

For example, as another example of the first embodiment, a scanning near-field microscope 300 shown in FIG.
Then, the dielectric beam splitter 32 is disposed on the common optical path behind the objective lens 31 with respect to the sample S. Further, behind the dielectric beam splitter 32, the detection light emitting section LD is arranged vertically downward so that the detection light L1 can be irradiated vertically toward the sample S.

In the scanning near-field microscope 300, the detection light emitting unit LD can irradiate the detection light L1 through the objective lens 31, so the distance between the objective lens 31 and the sample S is shortened. That is, the working distance (WD) of the objective lens 31 is shortened. Therefore, the objective lens 31 having a large numerical aperture (NA) can be used, and the S / N ratio can be further improved.

In the cantilever 10 of each of the embodiments described above, the observation light L3 is formed of a material that can transmit the observation light, and the observation light is transmitted. However, the invention is not limited to this. For example, the FIB is formed from the back surface of the cantilever toward the probe tip. A method of securing a waveguide by providing a fine through hole may be used.

Further, although the cantilever 10 is formed of silicon oxide, it may be formed of a permeable material such as silicon nitride.

Furthermore, although the method of detecting the amplitude of the cantilever is used as the control method, the control method is not limited to this, and for example, a method of detecting displacement without vibrating the cantilever may be used.

Furthermore, although the scanning probe microscope is applied to the scanning near-field microscope that observes the sample S using the evanescent light as described above, a scanning probe microscope that observes with other observation light may be used. For example, you may apply to a microspectrometer etc.

It is a block diagram which shows the scanning probe microscope which concerns on 1st Embodiment of this invention. It is a perspective view which shows the dielectric material beam splitter of the scanning probe microscope shown in FIG. FIG. 2 is a cross-sectional view of a sample and a cantilever showing a state where observation light is collected from the sample in the scanning probe microscope shown in FIG. 1. It is a block diagram which shows the scanning probe microscope which concerns on 2nd Embodiment of this invention. FIG. 4 is a cross-sectional view of a sample and a cantilever showing a state where observation light is collected from the sample in the scanning probe microscope shown in FIG. 3. It is a block diagram which shows the scanning probe microscope which concerns on 3rd Embodiment of this invention. FIG. 7 is a cross-sectional view of a sample and a cantilever showing a state where observation light is collected from the sample in the scanning probe microscope shown in FIG. 6. It is a block diagram which shows the other example of the scanning probe microscope which concerns on 1st Embodiment of this invention.

Explanation of symbols

L1 detection light L2 excitation light (irradiation light)
L3 Observation light S Sample (object to be measured)
1, 100, 200, 300 Scanning near-field microscope (scanning probe microscope)
10, 210 Cantilever 10b Cantilever opening 11, 211 Probe 20 Displacement detection mechanism 21, 221 Long pass filter (wavelength filter)
30, 130, 230, 330 Observation light receiving mechanism 31, 131 Objective lens 32, 120, 220 Dielectric beam splitter (optical filter)
40, 140, 240 Evanescent light generating means 41, 141, 241 Excitation light source (evanescent light irradiation mechanism)
121 Short pass filter (wavelength filter)

Claims (9)

A scanning probe microscope that measures the surface shape or physical properties of the object to be measured by relatively moving the cantilever and the object to be measured in a state where a cantilever having a probe at the tip is close to or in contact with the surface of the object to be measured. Because
An observation light receiving mechanism that collects and receives observation light emitted from the measurement region of the object to be measured facing the tip of the cantilever;
A displacement detection mechanism that detects the displacement of the cantilever by irradiating the cantilever with detection light having a wavelength different from that of the observation light and measuring the detection light reflected by the cantilever;
The optical path of the detection light and the optical path of the observation light are set so as to pass at least partially through the common optical path, and the transmittance of the observation light is higher on the common optical path than the detection light. Provided with an optical filter,
The displacement detection mechanism is disposed on an optical path of the detection light reflected from the cantilever;
A scanning probe microscope comprising a wavelength filter that transmits the detection light and cuts the excitation light and / or the observation light. The observation light receiving mechanism includes an objective lens that collects the observation light;
The displacement detection mechanism is set to irradiate the detection light through the objective lens, and the optical filter is disposed on the common optical path behind the objective lens with respect to the object to be measured. The scanning probe microscope according to claim 1.   3. The scanning type according to claim 1, wherein the optical filter is a beam splitter, and the optical path of the detection light and the optical path of the observation light are branched by the beam splitter. Probe microscope.   The scanning probe microscope according to claim 3, wherein the beam splitter is arranged directly above the cantilever, and the detection light is irradiated from directly above the cantilever.   The scanning probe microscope according to claim 3, wherein the beam splitter has an optical characteristic in which the reflectance of the detection light is higher than the reflectance of the observation light.   The scanning probe microscope according to claim 7, further comprising evanescent light generating means for generating evanescent light on the object to be measured. The evanescent light generating means includes an opening having a diameter of 100 nm or less formed at the tip of the probe;
An evanescent light irradiation mechanism for irradiating excitation light in the opening to generate evanescent light near the opening and irradiating the measurement area with evanescent light; and
The scanning probe microscope according to claim 6, wherein observation light generated in the measurement region is condensed at the opening and is incident on the optical filter.   The at least tip portion of the cantilever is formed of a material that can transmit the observation light, and the observation light receiving mechanism receives the observation light transmitted through the tip portion of the cantilever. The scanning probe microscope described.   The scanning probe according to claim 6, wherein the evanescent light generated on the surface of the object to be measured is scattered at the tip of the cantilever, and the observation light receiving mechanism receives the scattered light at the tip of the cantilever. microscope.

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