WO2017135732A1

WO2017135732A1 - Dual-channel scattering-type near-field scanning optical microscope

Info

Publication number: WO2017135732A1
Application number: PCT/KR2017/001191
Authority: WO
Inventors: 이은성; 권혁상
Original assignee: 한국표준과학연구원
Priority date: 2016-02-05
Filing date: 2017-02-03
Publication date: 2017-08-10
Also published as: KR20170093327A; KR101791669B1

Abstract

The present invention relates to a dual-channel scattering-type near-field scanning optical microscope and, more specifically, to a dual-channel scattering-type near-field scanning optical microscope characterized by two polarization states coexisting on the same path, each polarization beam forming independent interferometer, respectively, and polarization beams, which have different phases from each other, being measured in a dual-channel detector, respectively, thereby enabling quick measurement of only the optical-properties information of a specimen.

Description

Dual Channel Scattering Near Field Scanning Optical Microscope

The present invention relates to a dual channel scattering near-field scanning optical microscope, and more particularly, two polarization states coexist in the same path so that each polarizing beam forms an independent interferometer, and dual polarizing beams having different phases The present invention relates to a dual channel scattering near field scanning optical microscope that can measure each of the optical properties of a specimen quickly by measuring each at a channel detector.

As the line width of components and wiring structures in the microelectronics industry, magnetic materials and energy storage materials has recently decreased to less than 1 um, the characteristics of each component are evaluated more precisely, resolution, stability and Reliability is required.

In particular, microscopy techniques must have the same resolution as the line width in order to evaluate and detect various properties of the material on practically reactive non-uniform surfaces.

Since 1981, since scanning tunneling microscope (STM) and atomic force microscope (AFM) were developed by Binning and Rohrer, various types of scanning probe microscope (SPM) have been developed. It became.

Near-field scanning optical microscopy (NSOM) is also a device that measures local optical or optoelectronic properties with a resolution below the diffraction limit based on SPM.

Optical microscopy using NSOM has its own advantages over electron microscopes such as scanning electron microscope (SEM) and transmission electron microscope (TEM). And various combinations with other microscopy.

In addition, it is possible to distinguish non-uniform surfaces and dissimilar materials which are not possible with AFM. In other words, NSOM enables the characterization of surface structures by comparing surface images with optical images obtained using various optical contrast methods (fluorescence, absorption, reflection, polarization, birefringence, and spectroscopy).

This is why NSOM is one of the most commonly applied SPMs today.

NSOM is an advanced optical microscope with high resolution of tens of nanometers that overcomes the diffraction limit of light. It is well known that conventional optical or "far-field" range resolutions are quite limited due to diffraction.

The resolution of the diffraction limit is usually expressed as λ / NA, where λ is the wavelength of light and NA is the aperture of the microscope objective. The NA determines the light collecting capability of the lens, and usually, the larger the value, the more light can be collected. Also, the use of short wavelength light increases the resolution, which is generally limited by experimental difficulties.

This basic limitation was overcome by concentrating light using small holes with sub-diffraction sizes, which soon resulted in optical images below 50nm applicable to NSOM.

Related technologies include Korean Patent Publication No. 2003-0003249 (published on Jan. 09, 2003, name: Near Field Scanning Optical Microscope).

1 is a schematic diagram of a scattering type near field scanning optical microscope (s-NSOM) of NSOM.

Looking at the configuration of the scattering near-field scanning optical microscope 10 with reference to Figure 1, the s-NSOM is a light source 11, a probe 12 that is movable to the near-field region surrounding the surface of the specimen, and irradiated from the light source A beam splitter 13 for dividing the split light, driving means (not shown) for providing relative movement between the probe 12 and the sample surface, and cos position the light split through the beam splitter 13 And a reflection mirror 16 supported by the piezoelectric transducer 15 movable in the z-axis so as to be measurable at each sin position, and a photodetector 17.

As described above, the s-NSOM arithmetically processes the image measured at the cos position and the sin position while the piezo transducer is moved, so that only information on the optical properties can be obtained. If the image is measured only at the position, the information about the optical properties of the specimen and the shape information are mixed and the desired data cannot be obtained.

In other words, in the existing s-NSOM, in order to obtain only the information about the optical properties of the specimen, the images must be measured at two positions, and then subjected to arithmetic processing in the photodetector. This process is very cumbersome and can reduce the reliability of the data. There is a problem.

The present invention has been made to solve the above problems, and an object of the present invention is that two polarization states coexist in the same path so that each polarizing beam constitutes an independent interferometer, and polarizing beams having different phases Are measured by dual channel detectors, and only the optical properties of the specimen can be quickly measured without moving the piezo transducers to measure the images in two positions. To provide a measurable dual channel scattering near field scanning optical microscope.

Dual channel scattering near-field scanning optical microscope of the present invention comprises a light source (100) for irradiating light; A 45 degree polarizer 200 through which light generated from the light source 100 passes to generate first polarized light and second polarized light; A first beam splitter 310 for splitting the light passing through the 45 degree polarizer 200; A probe 500 disposed in a near field surrounding a surface of a specimen and scattering light passing through the focusing lens (or mirror) 510 through the first beam splitter 310; A first phase difference plate for generating a phase difference between the first polarized light and the second polarized light by passing the first polarized light and the second polarized light through the first beam splitter 310 and then reflecting the light on the reflection mirror. 410; The first polarized light and the second polarized light that are reflected by the reflection mirror and pass through the first phase difference plate 410 and the first beam splitter 310 and then interfere with the light scattered from the probe 500 are different from each other. A second beam splitter 320 for splitting into paths; A first detector 710 in which the first polarization component divided by the second beam splitter 320 is detected through the first objective lens 610; And a second detector 720 in which the second polarization component divided by the second beam splitter 320 is detected through the second object lens 620; Characterized in that it comprises a.

In addition, the scanning optical microscope 1 includes a first path L1 through which the light source passes through the focusing lens 510 and the probe 500, and the light source includes the first phase difference plate 410 and a reflection mirror 440. Including a second path (L2) passing through, wherein any one of the first path (L1) and the second path (L2) is disposed on the path through which the light passing through the first beam splitter 310 passes. The other one may be disposed on a path through which the light reflected by the first beam splitter 310 passes.

In addition, the first phase difference plate 410 may be a λ / 8 wave plate.

In addition, the scattering near-field scanning optical microscope (1) is located on the second path (L2), the second phase difference plate 420 and the polarizer 430 for making polarized light irradiated vertically or horizontally on the specimen, and the polarizer 430 It may be formed to include.

In addition, the second phase difference plate 420 may be a λ / 2 wave plate.

In addition, the dual channel scattering type near field scanning optical microscope 1 may be formed to include a third detector 730 for arithmetically processing the images detected by the first detector 710 and the second detector 720. have.

In addition, the first detector 710, the second detector 720, and the third detector 730 may be any one of a photodiode, a charge coupled device (CCD), and a MOS controlled thyristor (MCT).

The dual-channel scattering near-field scanning optical microscope of the present invention is the same pass without the cumbersome process of measuring the image in both positions while moving the piezo transducer to obtain only the information about the optical properties of the specimen in the conventional s-NSOM, Polarization states coexist so that each polarization beam forms an independent interferometer, and polarization beams having different phases are measured by dual channel detectors so that only optical property information of the specimen can be quickly measured.

In other words, the dual-channel scattering near-field scanning optical microscope of the present invention has an effect on the environmental change that may occur during the movement of the piezo transducer to measure only the optical property information of the specimen without the shape information in the existing s-NSOM. It can block, and images of two positions can be measured simultaneously by two detectors, reducing measurement time and improving reliability.

1 is a schematic diagram showing a conventional scattered near field scanning optical microscope (s-NSOM).

Figure 2 is a schematic diagram showing an embodiment of a dual channel scattering near field scanning optical microscope according to the present invention.

3 and 4 are schematic diagrams showing yet another embodiment of a dual channel scattering near field scanning optical microscope according to the present invention.

5 is a graph conceptually illustrating the phase difference between the first polarization and the second polarization through the first phase difference plate in the dual channel scattering near field scanning optical microscope according to the present invention.

Hereinafter, a dual channel scattering near-field scanning optical microscope according to the present invention as described above will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram showing a conventional scattering near-field scanning optical microscope (s-NSOM), Figure 2 is a schematic diagram showing an embodiment of a dual channel scattering near-field scanning optical microscope according to the present invention, Figures 3 and 4 Is a schematic view showing another embodiment of a dual channel scattering near field scanning optical microscope according to the present invention, Figure 5 is a first polarization and the first polarization plate through the first phase difference plate in the dual channel scattering near field scanning optical microscope according to the present invention It is a graph conceptually showing the phase difference of two polarizations.

As shown in FIG. 2, the dual channel scattering near-field scanning optical microscope 1 of the present invention photographs an interference pattern of interfering light after the light emitted from the light source 100 is reflected from the specimen and the probe 500. By measuring the internal structure and optical properties of the specimen, the light source 100, 45 degree polarizer 200, the first beam splitter 310, the probe 500, the first phase plate 410, the second beam The splitter 320 is formed to include a first detector 710 and a second detector 720.

First, the light source 100 is a light source for irradiating light, and may generate any one of infrared rays, visible rays, and ultraviolet rays.

The 45-degree polarizer 200 generates the first and second polarized light having different components while the light generated by the light source 100 passes.

In this case, the first polarized light and the second polarized light coexist on the same path, and each polarizing beam constitutes an independent interferometer.

As shown in FIG. 2, the first beam splitter 310 divides the light passing through the 45 degree polarizer 200 at a predetermined ratio, and at this time, part of the light emitted from the light source 100 Reflected and proceeds towards the reflecting mirror.

The first phase difference plate 410 is further provided on the optical path between the first beam splitter 310 and the reflection mirror to convert phases of the first and second polarizations having different components.

The first phase difference plate 410 generates a phase difference between the first polarized light and the second polarized light by passing some light reflected by the first beam splitter 310 and then reflecting the light again on the reflective mirror. Be sure to

In this case, the first phase difference plate 410 is a λ / 8 wave plate, and the first polarization and the second polarization are reflected by the reflection mirror so as to pass twice, thereby generating a total phase difference of λ / 4.

FIG. 5 is a graph conceptually illustrating the phase difference between the first polarization and the second polarization that passed through the first phase difference plate 410. If the first polarization means light at the cosine position, the second polarization means light at the sine position. The phase difference between the first polarized light and the second polarized light may be 90 °.

The probe 500 is disposed in a near field surrounding the surface of the specimen, and scatters the light passing through the focusing lens (or mirror) 510 through the first beam splitter 310, Atomic force microscope May be a probe 500.

In this case, the scanning optical microscope 1 includes a first path L1 through which the light source passes through the focusing lens 510 and the probe 500, and the light source includes the first phase difference plate 410 and a reflection mirror. And a second path L2 passing through 440, wherein any one of the first path L1 and the second path L2 is on a path through which the light passing through the first beam splitter 310 passes. The other one may be disposed on a path through which the light reflected by the first beam splitter 310 passes.

That is, as shown in FIG. 2, a focusing lens 510 is disposed on a path through which the light passing through the first beam splitter 310 passes, and a first phase difference plate 410 on a path through which the reflected light passes. ) May be disposed, and as shown in FIG. 4, the focusing lens 510 and the first phase difference plate 410 may be disposed at opposite positions to each other.

When disposed in the opposite position, the position of the first phase difference plate 410 and the reflection mirror 440, and the position of the probe 500 and the focusing lens 510 in FIG.

The dual channel scattering near-field scanning optical microscope 1 of the present invention further includes driving means for providing relative movement between the probe 500 and the surface of the specimen, and the driving means includes the probe 500. The x, y, z axis can be moved, and the specimen can be moved on the x, y, z axis.

In addition, the scattering near-field scanning optical microscope 1 of the present invention is located on the second path image (L2), the second phase difference plate 420 for making polarized light irradiated vertically or horizontally on the specimen, and a polarizer 430 may be further included.

In this case, the second phase difference plate 420 is a λ / 2 wave plate, and the light is reflected again after reaching the probe 500 so that the second phase difference plate 420 passes twice and no phase difference is generated.

The conventional scattering near field scanning optical microscope 1 is incident on the probe 500 without the second phase difference plate 420 and the polarizer 430 on the optical path between the first beam splitter 310 and the probe 500. The polarization angle to be adjusted had to be adjusted directly.

Next, the second beam splitter 320 is reflected by the reflection mirror, passes through the first phase difference plate 410 and the first beam splitter 310, and then interferes with light scattered from the probe 500. The first polarized light and the second polarized light are divided into different paths.

At this time, the first polarized light and the second polarized light passing through the second beam splitter 320 have interference with the light scattered from the probe 500 in a state where the phase difference is generated by the first phase difference plate 410. Is done.

Subsequently, in the first detector 710, the first polarization component divided by the second beam splitter 320 is detected through the first objective lens 610, and in the second detector 720, the second polarization component is detected. The second polarization component split by the beam splitter 320 is detected by passing through the second objective lens 620.

The dual channel scattering near-field scanning optical microscope 1 of the present invention arithmetically processes the images detected by the first detector 710 and the second detector 720, and finally obtains only the optical property information of the specimen to be obtained. It may be formed by further comprising a third detector 730 that can be obtained.

The first detector 710, the second detector 720, and the third detector 730 may be any one of a photodiode, a charge coupled device (CCD), and a MOS controlled thyristor (MCT).

The first detector 710, the second detector 720, and the third detector 730 are appropriately selected from a photodiode, a charge coupled device (CCD), and a MOS controlled thyristor (MCT) according to the wavelength of light. desirable.

Referring to Figure 3, when explaining the operation of the dual channel scattering near-field scanning optical microscope (1) of the present invention,

Firstly, the light irradiated from the light source 100 passes through the 45 degree polarizer 200, and thus the first and second polarization components are present.

Thereafter, the light passing through the first beam splitter 310 is divided into a predetermined ratio, and is divided into light traveling toward the probe 500 and light traveling toward the reflection mirror.

The light traveling toward the reflection mirror 440 passes through the first phase difference plate 410 located on the optical path, and is then reflected by the reflection mirror to pass through the first phase difference plate 410 once again. Through this process, a phase difference occurs between the first polarization and the second polarization.

When the first phase difference plate 410 is a λ / 8 wave plate, a phase difference of λ / 4 occurs between the first polarization and the second polarization.

Thereafter, the light passes through the first beam splitter 310 and passes through the second beam splitter 320 in a different path between the first polarized light and the second polarized light which interfere with the light scattered from the probe 500. Divided.

In this case, the first polarized light component passes through the first objective lens 610 to reach the first detector 710, and the second polarized light component passes through the second objective lens 620 to the second detector 720. Will be reached.

Finally, the third detector 730 arithmetically processes the images detected by the first detector 710 and the second detector 720, so that only optical property information of the specimen to be finally obtained can be obtained.

Accordingly, the dual channel scattering near-field scanning optical microscope (1) of the present invention is a cumbersome process of measuring images in two positions while the piezo transducer is moved to obtain only information on the optical properties of the specimen in the conventional s-NSOM. Two polarization states coexist in the same path so that each polarization beam constitutes an independent interferometer, and polarization beams having different phases can be measured by dual channel detectors, so that only the optical properties of the specimen can be measured quickly. Do.

That is, the dual channel scattering near-field scanning optical microscope 1 of the present invention is adapted to environmental changes that may occur during the time that the piezo transducer moves to measure only the optical property information of the specimen without the shape information in the existing s-NSOM. It can block the effects and the images of two positions can be measured simultaneously by two detectors, which can reduce the measurement time and improve the reliability.

The present invention is not limited to the above-described embodiments, and the scope of application of the present invention is not limited to those of ordinary skill in the art to which the present invention pertains without departing from the gist of the present invention as claimed in the claims. It goes without saying that modifications can be made.

(Explanation of the sign)

1: Dual Channel Scattering Near Field Scanning Optical Microscope

100: light source

200: 45 degree polarizer

310: first beam splitter 320: second beam splitter

410: first phase difference plate 420: second phase difference plate

430 polarizer 440 reflection mirror

500: probe 510: focusing lens

610: first objective lens 620: second objective lens

710: first detector 720: second detector

730: third detector

Claims

A light source 100 for irradiating light;

A 45 degree polarizer 200 through which light generated from the light source 100 passes to generate first polarized light and second polarized light;

A first beam splitter 310 for splitting the light passing through the 45 degree polarizer 200;

A probe 500 disposed in a near field surrounding a surface of a specimen to scatter light passing through the focusing lens 510 through the first beam splitter 310;

The first polarization and the second polarized light passing through the first beam splitter 310 is passed, and then reflected by the reflection mirror 440, a phase difference between the first polarized light and the second polarized light is generated 1 phase difference plate 410;

The first polarized light and the second polarized light that are reflected by the reflection mirror and pass through the first phase difference plate 410 and the first beam splitter 310 and then interfere with the light scattered from the probe 500 are different from each other. A second beam splitter 320 for splitting into paths;

A first detector 710 in which the first polarization component divided by the second beam splitter 320 is detected through the first objective lens 610; And

A second detector 720 which detects a second polarization component divided by the second beam splitter 320 through the second object lens 620; Dual channel scattering type near field scanning optical microscope comprising a.
The method of claim 1,

The scanning optical microscope (1)

A first path L1 through which the light source passes through the focusing lens 510 and the probe 500;

The light source includes a second path L2 passing through the first phase difference plate 410 and the reflection mirror 440,

One of the first path L1 and the second path L2 is disposed on a path through which the light passing through the first beam splitter 310 passes.

And the other is disposed on a path through which the light reflected by the first beam splitter 310 passes.
The method of claim 2,

The first phase difference plate 410 is

Dual channel scattered near field scanning optical microscope, characterized in that the lambda / 8 wave plate.
The method of claim 2,

The scattering near field scanning optical microscope (1)

Located on the second path (L2), the dual channel scattering, characterized in that it comprises a second phase difference plate 420 and polarizer 430 to make the polarized light irradiated vertically or horizontally on the specimen Type near field scanning optical microscope.
The method of claim 4, wherein

The second phase difference plate 420 is

Dual channel scattered near field scanning optical microscope, characterized in that the lambda / 2 wave plate.
The method of claim 2,

The dual channel scattering near field scanning optical microscope (1)

Dual channel scattering type near field scanning optical microscope, characterized in that it comprises a third detector (730) for arithmetically processing the image detected by the first detector (710) and the second detector (720).
The method of claim 6,

The first detector 710, the second detector 720 and the third detector 730 is

Dual channel scattered near field scanning optical microscope, characterized in that any one of a photodiode, a charge coupled device (CCD), a MOS controlled thyristor (MCT).