KR101735696B1 - Scanning electron microscopy and method for observing a sample using thereof - Google Patents

Scanning electron microscopy and method for observing a sample using thereof Download PDF

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KR101735696B1
KR101735696B1 KR1020150101358A KR20150101358A KR101735696B1 KR 101735696 B1 KR101735696 B1 KR 101735696B1 KR 1020150101358 A KR1020150101358 A KR 1020150101358A KR 20150101358 A KR20150101358 A KR 20150101358A KR 101735696 B1 KR101735696 B1 KR 101735696B1
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sample
electron beam
region
aperture
scanner
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KR20170010229A (en
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조복래
안상정
박인용
한철수
김진규
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한국표준과학연구원
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B21/00—Microscopes
    • G02B21/0004—Microscopes specially adapted for specific applications
    • G02B21/002—Scanning microscopes
    • G02B21/0024—Confocal scanning microscopes (CSOMs) or confocal "macroscopes"; Accessories which are not restricted to use with CSOMs, e.g. sample holders
    • G02B21/0036—Scanning details, e.g. scanning stages
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01Q—SCANNING-PROBE TECHNIQUES OR APPARATUS; APPLICATIONS OF SCANNING-PROBE TECHNIQUES, e.g. SCANNING PROBE MICROSCOPY [SPM]
    • G01Q30/00—Auxiliary means serving to assist or improve the scanning probe techniques or apparatus, e.g. display or data processing devices
    • G01Q30/02—Non-SPM analysing devices, e.g. SEM [Scanning Electron Microscope], spectrometer or optical microscope
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B21/00—Microscopes
    • G02B21/0004—Microscopes specially adapted for specific applications
    • G02B21/002—Scanning microscopes
    • G02B21/0024—Confocal scanning microscopes (CSOMs) or confocal "macroscopes"; Accessories which are not restricted to use with CSOMs, e.g. sample holders
    • G02B21/0036—Scanning details, e.g. scanning stages
    • G02B21/0048—Scanning details, e.g. scanning stages scanning mirrors, e.g. rotating or galvanomirrors, MEMS mirrors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/10—Scanning
    • G01N2201/104—Mechano-optical scan, i.e. object and beam moving
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/10—Scanning
    • G01N2201/11—Monitoring and controlling the scan
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2223/00—Investigating materials by wave or particle radiation
    • G01N2223/30—Accessories, mechanical or electrical features
    • G01N2223/33—Accessories, mechanical or electrical features scanning, i.e. relative motion for measurement of successive object-parts
    • G01N2223/3301—Accessories, mechanical or electrical features scanning, i.e. relative motion for measurement of successive object-parts beam is modified for scan, e.g. moving collimator
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2223/00—Investigating materials by wave or particle radiation
    • G01N2223/30—Accessories, mechanical or electrical features
    • G01N2223/335—Accessories, mechanical or electrical features electronic scanning

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Abstract

The present invention relates to an electron beam source which emits an electron beam; At least one intermediate focusing lens provided at the electron beam source side for focusing the electron beam and an objective lens provided at the sample side as a final focusing lens and forming an electron beam spot focused on the sample; A vacuum chamber having an electron beam source and a focusing lens group therein and having an aperture which is a passage through which the electron beam emitted from the electron beam source is irradiated to the sample through the objective lens; At least one deflector for controlling and changing the irradiation direction of the electron beam; A sample scanner supporting the sample to be observed and capable of finely moving the sample horizontally; And a sample stage provided below the sample scanner and capable of horizontally moving the sample and the sample scanner together.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning electron microscope and a method for observing a sample using the same.

The present invention relates to a scanning electron microscope and a method of observing a sample using the same.

A scanning electron microscope is an apparatus for observing the surface of a sample using an electron beam. Normally, in the vacuum state, electron beams are irradiated to a sample to detect secondary electrons emitted from the sample, thereby obtaining surface information of the sample.

On the other hand, when a scanning electron microscope is used for observation of a bio sample or the like, it is necessary to observe the surface morphology or structure of the sample under an atmospheric pressure or a low vacuum atmosphere without observing it in a vacuum state. (E-SEM) or Air Scanning Electron Microscope (Air-SEM), which are different from conventional scanning electron microscopes, and an electron beam passes between the objective lens and the sample It is possible to obtain a pressure difference between an area irradiated with the electron beam and a region containing the sample.

 1 shows an environmental scanning electron microscope according to the prior art. More specifically, the scanning electron microscope includes an electron beam source 10 in a vacuum chamber 30, an intermediate focusing lens 22 provided in an electron beam source side in the vacuum chamber, and an objective lens 24, a vacuum chamber 30 having an aperture 35, which is a passage through which an electron beam emitted from the electron beam source is irradiated onto the sample through the objective lens, and the intermediate focusing lens 30, A deflector 40 provided between the objective lens and controlling the irradiation direction of the electron beam and a sample stage 50 capable of supporting and moving the sample 55 located outside the vacuum chamber.

Here, the scanning electron microscope in FIG. 1 focuses the electron beams emitted from the electron beam source in the vacuum chamber into a plurality of focusing lens groups to form a beam spot, that is, a probe focused on the sample, using one or more deflectors And the shape of the sample is observed by scanning the electron beam on the sample by moving the position of the probe by adjusting the beam trajectory. Since the electron beam can collide with the air molecules and scatter, the space inside the vacuum chamber including the electron beam source and the beam scanning region between the focusing lens group and the aperture 35 is guided to the high vacuum environment .

At this time, the vacuum pump may be provided so as to have a pressure of 10 -4 mbar or less, preferably 10 -5 mbar or less, in order to maintain a high vacuum in the vacuum chamber including the electron beam source and the focusing lens group.

At this time, the electron beam emitted from the electron beam source is focused by the rotationally symmetrical electric field or magnetic field derived from the focusing lens group around the optical axis 60 indicated by the dotted line in FIG. Here, in the case of an electron beam, a magnetic field formed by an electric field or an electric coil formed by an electrode other than an optical system serves as a focusing lens group.

Here, the size of the probe, which is a beam spot focused on the surface of the sample by the focusing lens group, determines the resolution when observing the shape of the sample and the accuracy of the probe when processing the sample. Generally, the smaller the probe size, the better the resolution and precision.

On the other hand, in general, the lens has an aberration, the size of the probe is determined by the aberration, and as the aberration increases, the probe size becomes large, and the observation resolution and the processing accuracy are lowered.

Further, if the trajectory of the electron beam deviates from the center of the objective lens, the aberration rapidly increases and the spot size becomes large. Therefore, in order to prevent this, a deflector may be generally provided on the objective lens.

Fig. 2 shows a scanning electron microscope in the prior art for use in a sample with a deflector and in a low vacuum environment. In Fig. 3, a scanning electron microscope in the prior art for a sample placed under atmospheric pressure with a deflector Respectively.

In FIG. 2 or 3, a deflector is arranged between the objective lens and the intermediate focusing lens in order to reduce the aberration when the beam is scanned on the sample, and the beam trajectory is controlled so that the trajectory of the beam passes through the center of the lens have.

In general, as shown in FIG. 2, when the electron beam is irradiated onto the sample in a low vacuum environment, the pressure of the sample room including the sample can be maintained at a relatively low vacuum level of 1x10 -2 mbar or more, A separate vacuum pump is provided to maintain a low vacuum of the electron beam source and the vacuum chamber in the high vacuum region including the electron beam source and the focusing lens group.

In this case, the aperture may be formed so as to open in the form of an opening in the vacuum chamber, and the aperture and the area of the aperture, the capacity of each vacuum pump, etc., The pressure difference between the areas can be adjusted.

On the other hand, in order to observe or process the biological sample, the sample is placed under the atmospheric pressure without using the vacuum chamber in the sample room area including the sample as shown in Fig.

In this case, the aperture forms the diaphragm 37 having a certain thickness, not the opening as shown in FIG. The diaphragm may be made of, for example, a material such as SiN or a thin film material such as graphene itself, and the thickness may range from 1 to 2000 nm, preferably from 2 to 500 nm.

On the other hand, in the case of the scanning electron microscope including the aperture in FIG. 2 or FIG. 3, the maximum forming area of the electron beam probe formed on the sample can be determined by limiting the scanning angle of the charged particle beam by the size of the aperture Also, since the scanning angle of the charged particle beam is limited by the distance between the aperture and the objective lens, the maximum forming area of the electron beam probe formed on the sample can be determined, thereby limiting the range in which the surface of the sample can be measured.

That is, when the size of the aperture is large or the distance between the aperture and the objective lens is short, the scanning range, which is a region where the probe can be formed using the deflector in a fixed state without moving the sample, On the contrary, if the aperture size is small or the distance between the aperture and objective lens is long, the scanning range becomes narrow.

In general, observing or processing a sample through the control of a focusing lens group and a deflector, etc., by fixing the above-mentioned sample fixes the control conditions of the focusing lens group and the deflector, In the scanning electron microscope including the apertures as described above, there is a method of fixing the sample and adjusting the irradiation direction of the electron beam, The range of the electron beam irradiation region in the sample depends on the size of the aperture and the distance between the aperture and the objective lens.

Further, when the size of the aperture is large, it is difficult to maintain the pressure difference between the area including the sample and the area inside the vacuum chamber including the electron beam source, so that the charged particle beam can collide with the air molecules and scatter, There is even a limitation that can have an unreasonable impact on the system.

For example, in an E-SEM (Environmental Scanning Electron Microscope) as shown in FIG. 2, the pressure of the sample chamber is maintained at a low vacuum level of 1 x 10 -2 mbar or more, (<1 mm) of the aperture communicating the inside of the vacuum chamber of the high vacuum region and the sample chamber region of the low vacuum region so as not to affect the high vacuum state of 1 x 10 -4 mbar or less .

In the air-scanning electron microscope (SEM) as shown in FIG. 3, the pressure around the sample is kept at atmospheric pressure, and a high vacuum state of 1 x 10 -4 mbar or less in the vacuum chamber including the electron beam source The thickness of the aperture should be very small (<1 mm) and less than a certain thickness (<several hundred nanometers) so as not to affect the maintenance.

As a conventional technique for such a scanning electron microscope, European Patent Publication EP 0786145 B1 describes an environmental scanning electron microscope (E-SEM) which gives excellent spatial resolution even when a sample is accommodated in a gas environment of a sample room , J. Vac. Sci. Technol. B 9, 1557 (1991) describes an air scanning electron microscope (SEM) capable of observing a sample under atmospheric pressure using a silicon nitride thin film.

However, in the prior arts including the above prior art, in order to reduce the aberration in the objective lens which is the final focusing lens, the electron beam trajectory must be guided to the deflector such that the electron beam trajectory always passes through the center of the objective lens, And the electron beam must pass through the center of the objective lens. In order to pass through the aperture in FIG. 2 and FIG. 3, the scanning range must be narrowed.

As a result, it has a problem that the field of view of the sample region narrows in the case of the scanning electron microscope, and in the process of observing the region of interest (ROI) through microscopic observation, : Region of interest), and it is difficult to quickly find the position of the region of interest. By solving the problem, it is possible to obtain the high-resolution image of the region of interest by electron beam by quickly grasping the position of the region of interest in the sample. This can be an important factor.

Therefore, in order to observe a sample using a scanning electron microscope, it is preferable to develop a scanning electron microscope capable of observing a large area in the sample to determine a position of a region of interest, There is a continuing need for a method for observing a sample using the same.

European Patent Publication EP 0786145 B1 (Dec. 15, 2004)

J. Vac. Sci. Technol. B 9, 1557 (1991), Atmospheric scanning electron microscopy using silicon nitride thin film windows, E. D. Green and G. S. Kino.

Accordingly, in order to solve the above problems, the present invention can observe a sample by irradiating a large area of the sample with an electron beam, and thereby locate a region of interest, thereby performing fine observation of the region of interest It is an object of the present invention to provide a possible scanning electron microscope.

The present invention also relates to a scanning electron microscope capable of microscopically observing a region of interest by observing a wide region of the sample optically by adding optical observation means to the scanning electron microscope, It is a further object of the present invention to provide

The present invention also provides a method for observing a sample in which a region of interest is observed by observing a large region of the sample using the scanning electron microscope and then microscopically observes the region of interest through the observation of the region of interest. The purpose.

The present invention relates to an electron beam source which emits an electron beam; At least one intermediate focusing lens provided at the electron beam source side for focusing the electron beam and an objective lens provided at the sample side as a final focusing lens and forming an electron beam spot focused on the sample; A vacuum chamber having an electron beam source and a focusing lens group therein and having an aperture which is a passage through which the electron beam emitted from the electron beam source is irradiated to the sample through the objective lens; At least one deflector for controlling and changing the irradiation direction of the electron beam; A sample scanner supporting the sample to be observed and capable of finely moving the sample horizontally; And a sample stage provided below the sample scanner, the sample stage being capable of horizontally moving the sample and the sample scanner, wherein the scanning electron microscope has a first region inside the vacuum chamber and a second region inside the vacuum chamber, And a second area including the sample. The horizontal movable range of the sample scanner is smaller than the horizontally movable range of the sample stage, so that the area to be irradiated with the electron beam can be finely adjusted And a scanning electron microscope.

As an embodiment, there is provided an image detecting device for obtaining an optical image of a sample reflected by the mirror in a downward direction of the mirror, the mirror having an image of the sample reflected between the aperture and the sample And the mirror can be positioned perpendicular to the optical axis of the electron beam.

In one embodiment, the scanning electron microscope is provided with a separate plate including a hole through which an electron beam can pass, in a lower portion of the aperture, and a mirror is provided under the plate, or the scanning electron microscope is provided with an objective lens And a mirror may be provided around the aperture at the lower end of the objective lens integrated with the aperture.

In addition, the present invention can provide a method of observing a sample using the scanning electron microscope.

The present invention also relates to an electron beam source for emitting an electron beam; At least one intermediate focusing lens provided at the electron beam source side for focusing the electron beam and an objective lens provided at the sample side as a final focusing lens and forming an electron beam spot focused on the sample; A vacuum chamber having an electron beam source and a focusing lens group therein and having an aperture which is a passage through which the electron beam emitted from the electron beam source is irradiated to the sample through the objective lens; At least one deflector for controlling and changing the irradiation direction of the electron beam; A sample scanner supporting the sample to be observed and capable of finely moving the sample horizontally; And a sample stage provided at a lower portion of the sample scanner and capable of moving the sample and the sample scanner horizontally together, wherein the sample stage has a first region inside the vacuum chamber and a second region having a relatively higher pressure than the first region, And a horizontal movable range of the sample scanner is smaller than a horizontally movable range of the sample stage so that the sample can be scanned using a scanning electron microscope capable of finely adjusting the region irradiated with the electron beam, Setting and maintaining a pressure in each of the regions so that the pressure in the first region, which is the inner region of the vacuum chamber, has a pressure that is relatively lower than the pressure in the second region including the sample; Acquiring sample surface information of a wide area by irradiating the electron beam while fixing the electron beam in a sample direction and moving the sample through the movement of the sample scanner; And controlling the irradiation direction of the charged particle beam in the sample by controlling the at least one deflector to fix surface of the sample in a narrow region to be desired based on the acquired sample surface information of the obtained wide region And acquiring sample surface information in a narrow region. The present invention also provides a method of observing a sample using a scanning electron microscope.

The present invention can provide a scanning electron microscope capable of observing a sample while ensuring a wider field of view than the measurement range of the sample, which was limited by the size of the aperture at the time of irradiation of the electron beam.

That is, in the scanning electron microscope according to the present invention, the electron beam is fixed in the direction of the sample and irradiated, and the sample is moved by the sample scanner located between the sample and the sample stage to change the path of the charged particle beam. The position of the region of interest in the sample can be easily grasped by using the electron microscope, and the position of the region of interest in the sample can be easily grasped by using the electron microscope. Thus, after the sample is fixed on the basis of the position, So that the sample surface information of the region of interest (narrow region) can be obtained quickly and easily.

Further, in the case of the scanning electron microscope according to the present invention, as described above, a mirror is provided between the aperture and the sample so that the image of the sample can be reflected, and a sample reflected by the mirror in the lower direction of the mirror An optical image of a large area in the sample can be additionally obtained by using the image detecting device for obtaining the optical image of the sample. As a result, the position of the region of interest in the sample can be easily grasped through the optical image, The irradiation direction of the electron beam can be precisely adjusted by the deflector after fixing, so that the sample surface information of the region of interest (narrow region) can be obtained quickly and easily.

1 is a view showing a scanning electron microscope according to the prior art.
FIG. 2 is a scanning electron microscope according to the related art, in which the electron beam is irradiated in a low-vacuum environment.
3 is a scanning electron microscope according to the related art, in which the electron beam is irradiated in the environment of the atmospheric pressure.
4 is a scanning electron microscope (SEM) in which a sample scanner is mounted between a sample and a sample stage according to an embodiment of the present invention.
5 is a view illustrating a state in which a sample scanner moves in a state in which an electron beam is fixed and an electron beam is scanned over a large area in the sample to acquire surface information of the sample in a wide area according to another embodiment of the present invention It is a picture.
FIG. 6 is a view showing a state in which the electron beam scans the region of interest (narrow region) in the sample by the deflector to acquire the surface information of the sample in a narrow region, according to another embodiment of the present invention.
Fig. 7 is a schematic view of a scanning electron microscope according to another embodiment of the present invention, in which a mirror is provided between an aperture and a sample so that an image of the sample can be reflected, A scanning electron microscope having an image detecting device for obtaining an optical image of a sample.
FIG. 8 is a diagram illustrating an image obtained by allowing an electron beam to scan a large area in a sample by moving a sample scanner in a state where an electron beam is fixed, (Bottom) showing the image obtained by scanning the region of interest in the sample with the electron beam adjusted by the deflector to obtain an image of the region.

Hereinafter, an apparatus and a method of the present invention will be described in detail with reference to the accompanying drawings. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. In the accompanying drawings, the dimensions of the structures are enlarged to illustrate the present invention in order to clarify the present invention. Numbers (e.g., first, second, etc.) used in the description process of the present invention are merely an identifier for distinguishing one component from another.

Unless otherwise defined in this invention, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

FIGS. 4 to 6 are scanning electron microscopes having apertures, according to an embodiment of the present invention, in which a sample scanner is mounted between a sample and a sample stage. FIG.

Which comprises an electron beam source 10 for emitting an electron beam; At least one intermediate focusing lens (22) provided at the electron beam source side for focusing the electron beam, and an objective lens (24) provided at the sample side as a final focusing lens and forming an electron beam spot to be focused on the sample A lens group 20; A vacuum chamber (30) having the electron beam source and a group of focusing lenses therein, the aperture chamber being a passage through which the electron beam emitted from the electron beam source is irradiated to the sample through the objective lens; At least one deflector (40) for controlling and changing the irradiation direction of the electron beam; And a sample scanner (56) supporting the sample (55) to be observed and capable of finely moving the sample horizontally; And a sample stage (50) provided below the sample scanner and capable of horizontally moving the sample and the sample scanner, wherein the scanning electron microscope comprises a first region inside the vacuum chamber, A second region having a relatively high pressure and including the sample,

The horizontal movable range of the sample scanner is smaller than the horizontally movable range of the sample stage so that the area irradiated with the electron beam can be finely adjusted.

The scanning electron microscope in the present invention may include a secondary electron detector 100 as an additional component, or a back scattered electron detector (not shown).

Here, the focusing lens group 20 including the electron beam source, the intermediate focusing lens 22, and the objective lens 24, the vacuum chamber 30 including the aperture and the sample stage 50 are shown in FIGS. 2 and The components used in the prior art, such as those described in 3, can be used as is.

In more detail, the electron beam used in the present invention is not limited to the type in which the electron beam is emitted from the electron beam source and the irradiation direction of the particle beam can be controlled by the focusing lens group 20 and the deflector 40 It can be used without.

Further, the electron beam source used in the present invention may include a thermionic emission source such as a tungsten filament capable of emitting an electron beam.

As the thermionic emission source, filaments of tungsten, tantalum, iridium, and iridium-tungsten alloys, which have a high melting point and a relatively good electron emission, and filaments of yttrium, barium, cesium and its oxides May be used.

The focusing lens group 20 serves to converge the electron beam by an electric field or a magnetic field. The focusing lens group 20 is provided on the sample side as one or more intermediate focusing lenses 22 and a final focusing lens provided on the electron beam source side, And an objective lens 24 for forming an electron beam probe which is a focused beam spot.

The converging lens group 20 including the intermediate focusing lens 22 and the objective lens in the focusing lens group can decelerate or accelerate the electron beam emitted from the electron beam source or change the irradiation direction And may exist in a plurality of coil shapes wound in various shapes.

At this time, the electron beam may be controlled to pass through the center of the objective lens to reduce the aberration. That is, the beam deflected by the deflector at the time of scanning can be controlled to pass through the center of the objective lens which is the final focusing lens.

In order to realize this, in the present invention, a deflector used in the prior art may be provided between the intermediate focusing lens and the objective lens, as in the prior art, and the irradiation direction of the electron beam can be controlled by the deflector.

Further, in the present invention, the deflector may include at least one coil device that generates a magnetic field used to deflect the charged particle beam.

The deflector is generally provided between the intermediate focusing lens 22 and the objective lens 24 in the prior art. 2 and 3, a plurality of deflectors are provided between the intermediate focusing lens 22 and the objective lens 24 at the upper end 41 and the lower end 42, So that the beam trajectory can be set so as to pass through the center.

At this time, depending on the size of the aperture, the maximum angle of the electron beam irradiated on the sample with respect to the optical axis may be limited. For example, referring to FIG. 2, the electron beam irradiated on the sample may be irradiated onto the sample while being restricted to a spatial range having an angle smaller than the maximum angle so as to pass through an opening inside the portion corresponding to the outermost portion of the aperture If the angle is further widened and irradiated, the aperture can not pass through the aperture.

In order to solve this problem, in the present invention, the deflector can be positioned between the objective lens and the sample, and the region irradiated with the electron beam can be freely extended through the beam.

That is, a deflector is provided between the objective lens and the sample, and the distance between the deflector and the aperture is controlled to enlarge or narrow the observation region of the sample. In this case, the deflector may be provided so as to be adjustable in height in the Z direction, which is the optical axis direction.

When the deflector is provided at the position between the objective lens and the sample as described above, the electron beam passes through the center of the objective lens, and then the direction of the beam trajectory is controlled by the deflector, It is possible to perform beam irradiation in a much wider area.

For example, if the deflector is placed between the objective lens and the sample, the range of the sample that can be observed becomes wider as the deflection point corresponding to the position where the beam irradiation direction is changed by the deflector approaches the sample in the objective lens, The scope of investigation will also be broadened.

Therefore, the electron beam irradiated on the sample after passing through the center of the objective lens can control the direction of the beam trajectory by means of a single deflector, and as in the prior art, a plurality of deflectors are provided between the objective lens and the intermediate focusing lens There is an advantage that the irradiation region of the sample can be controlled simply and without needing to be performed.

Further, the scanning electron microscope of the present invention may include a vacuum chamber having an aperture, which is a passage through which the electron beam emitted from the electron beam source is irradiated to the sample through the objective lens.

The scanning electron microscope of the present invention can be divided into a first region inside the vacuum chamber surrounded by the vacuum chamber and a second region including the sample and the second region has a relatively higher pressure than the first region I have.

More specifically, the first region may be a high vacuum region having a range of 10 -4 mbar or less, and preferably a high vacuum region having a range of 10 -5 mbar or less.

To this end, a vacuum system including a high vacuum vacuum pump may be provided to maintain the pressure inside the vacuum chamber.

Illustratively, the vacuum chamber forms a vacuum space in which a high vacuum is maintained by a vacuum pump. The vacuum pump may be a dry pump, a diffusion pump, a turbo molecular pump, an ion pump, a cryopump, a rotary pump, a scroll or a diaphragm pump Of a dry pump of the &lt; / RTI &gt;

In this case, the second region may be a region including a sample, and may correspond to an area of an interior portion of the sample where the sample is located. The sample chamber may be a region depressurized by a separate low vacuum vacuum pump Or may be an open area under the same pressure as the ambient air as in the atmospheric pressure environment as in Fig.

Meanwhile, in the present invention, the pressure difference between the first region and the second region may exhibit a pressure difference of 100 times or more, and preferably a pressure difference of 1000 times or more.

Further, in the present invention, the aperture may be a boundary for distinguishing the first region and the second region. That is, the aperture is an opening in the form of a hole having a circular, polygonal, elliptical or arbitrary shape in cross section, which is divided into a first region including a vacuum chamber interior region and a second region including a sample, The first region and the second region communicate with each other through the apertures and may be open to each other or may have a shape in which the opening portion of the opening is sealed by a thin diaphragm according to the degree of vacuum of the second region being the sample region .

The size of the aperture may be less than or equal to 3000 m in diameter, preferably less than or equal to 2000 m, and more preferably less than or equal to 1000 m.

Thus, the vacuum chamber is partially sealed by an aperture with an aperture or sealed by an aperture containing a diaphragm so that the electron beam emitted from the electron beam source in the vacuum chamber can be irradiated onto the sample without scattering.

In the present invention, when the pressure in the sample chamber including the sample is a low vacuum having a pressure range of 10 -3 mbar or more, and preferably a pressure range of 10 -2 mbar or more, the apertures are mutually opened so as to have only the opening shape, The atmosphere of the second region which is the sample region can be freely introduced into the first region inside the vacuum chamber.

The pressure in the first region and the pressure in the second region may be varied according to the measurement point of the pressure when the aperture is opened in the form of an opening, The region may be near the electron beam source circle, and the second region may be near the sample on the sample stage.

In the case where the pressure in the second region including the sample is atmospheric pressure, the pressure of the first region in the vacuum chamber including the electron beam source may not be easy to control, The emission of the electron beam beam can be scattered or interrupted by air particles present in the atmospheric pressure so that the aperture can be in the form of an aperture sealed by a thin thickness diaphragm as in Fig.

Therefore, when the aperture is sealed by the diaphragm as described above, the first region can be isolated from the second region.

In this case, the thickness of the diaphragm is not particularly limited as long as it can penetrate the electron beam. Specifically, it may be 10 nm to 3000 nm, preferably 20 nm to 2000 nm, more preferably 20 nm 500 nm.

The diaphragm material may be any one selected from silicon nitride (SiN) and graphene, or a composite layer thereof.

In the present invention, the sample is placed in the sample chamber below the objective lens. At this time, as described above, the pressure in the sample room is maintained under an atmospheric pressure or a low vacuum pressure, and the surface of the sample can be exposed to an electron beam beam.

Also, in the present invention, the sample may be supported by a sample scanner, and the sample scanner may be supported by a sample stage provided under the sample scanner.

More specifically, the sample scanner supports the sample to be observed, and is capable of moving the sample more finely horizontally than the moving range of the sample stage, and is provided on the sample stage.

The scanning electron microscope of the present invention is characterized in that a sample scanner is provided on a sample stage for moving the sample room and the sample is moved so that the horizontally movable range of the sample scanner is smaller than the horizontally movable range of the sample stage, This makes it possible to finely control the region irradiated with the electron beam.

In one embodiment, the horizontally movable range of the sample scanner may be in the range of 1000 um to 5 nm, preferably 500 um to 10 nm.

In addition, the sample scanner can be driven by a piezoelectric motor. 2. Description of the Related Art Generally, a piezoelectric motor is a motor having a piezoelectric element and having a driving force by friction between a stator and a rotor using the piezoelectric element. For example, a nanomanipulator composed of a piezo electric stage may be used.

That is, the sample scanner can move in units of nanometers (nm) or micrometers (um) in the x-axis and y-axis directions, similar to a nanomanipulator composed of a piezoelectric electric stage. Axis and y-axis stages provided on the stage, and a piezoelectric motor provided on each of the stages to move each stage in units of nanometers (nm) or micrometers (um).

That is, the x-axis stage is moved with the degree of freedom in the x-axis direction by the piezoelectric motor, and the y-axis stage can be moved with the degree of freedom in the y-axis direction by the piezoelectric motor.

As a scanning electron microscope used in the prior art, in the case of an environmental scanning electron microscope or an air scanning electron microscope with an aperture, the sample stage supporting the sample generally has a diameter of 0.1 to 100 mm, preferably 1 And the sample stage in the present invention may be provided so as to be movable in the x direction and the y direction parallel to the paper surface and in the z direction perpendicular to the paper surface, The sample stage can be used, or the sample can be supported only by the sample scanner without moving the sample stage, if necessary, and the sample can be moved.

However, when the sample is observed by irradiating the sample with an electron beam using a scanning electron microscope having an aperture, which is used in the prior art, the sample stage having a very large range of horizontal movement as compared with the electron beam scanning range is moved The moving range of the sample due to the movement of the sample stage may become much larger than the observation range of the sample due to the irradiation of the electron beam and it may be difficult to locate the observation region according to the irradiation of the electron beam, .

Therefore, conventionally, a method of adjusting a scan area of a sample by fixing a sample and controlling a deflector or the like before irradiation of an electron beam has been used, but in the present invention, a sample scanner is provided between the sample and the sample stage, The horizontal movable range is set to be smaller than the horizontally movable range of the sample stage and the sample is moved using the sample scanner for the observation range of a large area in the sample to obtain information of the sample surface by irradiation of the electron beam The microscopic range in the region of interest requiring analysis is determined by scanning the surface of the sample by fixing the sample and adjusting the irradiation position of the electron beam.

On the other hand, the present invention can be equipped with an optical image detecting device below the scanning electron microscope to obtain an optical image of a sample.

To this end, the scanning electron microscope of the present invention has a mirror between which an image of the sample can be reflected between the aperture and the sample, and an image for obtaining an optical image of the sample reflected by the mirror in a downward direction of the mirror And a detection device.

The optical image detecting device may be a camera or an image sensor, and may be provided with an illumination (not shown) to photograph the surface of the sample.

Here, the optical image detecting device may be a camera or an image sensor, and a CCD sensor or a CMOS sensor may be used as the image sensor.

In this case, the mirror may be positioned perpendicular to the optical axis of the electron beam.

The mirror may be provided with a separate plate of a sample room of a scanning electron microscope including an aperture, or may be coupled to a component such as the lower surface of the objective lens of a scanning electron microscope.

In other words, when a separate plate is provided in the sample and is coupled to the plate, a separate plate including a hole through which an electron beam can be transmitted may be provided in the lower part of the aperture, a mirror may be provided under the plate, When the lens is coupled to the lower surface of the lens, a mirror is provided around the aperture at the lower end of the objective lens having an aperture integrated with the objective lens so that the sample can be positioned in the lower direction of the mirror.

7 is a scanning electron microscope in which the mirror and the optical image detecting device are provided at the bottom of the sample. The scanning electron microscope includes a mirror in which an image of a sample can be reflected between an aperture and a sample in a scanning electron microscope, And an image detecting device for obtaining an optical image of the sample reflected by the mirror.

The optical image of the sample can be easily and preferentially obtained through the scanning electron microscope having the mirror and the optical image detecting device according to the present invention. Based on this, it is possible to quickly grasp the region of interest, It can be obtained through investigation. In this case, the scanning electron microscope of the present invention fixes the scanning direction of the electron beam and compares or overlaps the electron microscope image of the sample obtained through the movement of the sample scanner and the optical image, And thus, it is possible to more effectively find a region of interest.

Meanwhile, the vacuum chamber of the present invention may include at least one externally accessible connector. The connector is a connection part for electrical connection between the vacuum chamber and the external environment, and supplies power and control signals to the electron beam source and the focusing lens group in the vacuum chamber. (Ii) When the additional deflector is provided in the vacuum chamber, Power supply, and (iii) power supply and control of the detector capable of providing information about the presence or absence of an electron beam source, focusing lens group, and deflector in (i) and (ii).

Further, the scanning electron microscope of the present invention may have various additional components depending on its application field. For example, when used in an environmental scanning electron microscope, various signals emitted from the surface of the sample, such as a low energy secondary electron signal, a high energy backscattering electron signal, a small angle of reflected electron signal, Lt; RTI ID = 0.0 &gt; geometry &lt; / RTI &gt;

The detector is connected to a display device, such as a display device, which displays the shape of the surface of the sample, and information is finally displayed as an image.

In addition, the scanning electron microscope of the present invention may further include a control unit for controlling the focusing lens group and the deflector, and controlling the position of the sample stage, adjusting the emission intensity and emission timing of the electron beam in the electron beam source.

At this time, the controller for controlling the degree of vacuum of the vacuum chamber including the electron beam source and the degree of vacuum of the sample room may be separately or integrally included in the control unit, whereby the pressure of each region can be respectively controlled .

The present invention also provides a method for observing a sample using the scanning electron microscope.

More specifically, it relates to the sample scanner; And a sample stage provided below the sample scanner and capable of moving the sample and the sample scanner horizontally together. The horizontally movable range of the sample scanner has a range smaller than the horizontally movable range of the sample stage, Wherein a pressure of a first region, which is an inner region of the vacuum chamber, is lower than a pressure of a second region including the sample, the method comprising the steps of: Setting and maintaining a pressure of each region so as to have a pressure; Acquiring sample surface information of a large area by irradiating the electron beam while fixing the electron beam in the sample direction and moving the sample through the movement of the sample scanner; And controlling the irradiation direction of the charged particle beam in the sample by controlling the at least one deflector to fix surface of the sample in a narrow region to be desired based on the acquired sample surface information of the obtained wide region , And obtaining the sample surface information of the narrow region.

This is accomplished by using the above-described scanning electron microscope of the present invention and irradiating the electron beam while fixing the electron beam in the direction of the sample in order to acquire the sample surface information in a wide area by the sample scanner located between the sample and the sample stage By moving the sample finely, the spatial resolution is lower than the method of obtaining the image by changing the path of the electron beam through the control of the deflector corresponding to the image acquiring method of a commonly used electron microscope. However, And obtaining the sample surface information of the region.

FIG. 5 is a diagram illustrating a state in which a sample scanner moves in a state in which an electron beam is fixed, thereby acquiring surface information of a sample in a wide region by allowing an electron beam to scan a large region in the sample, according to an embodiment of the present invention , Thereby allowing the user to search for a region of interest on the surface of the sample or to select a specific region on a sample region of a large area.

FIG. 6 is a view illustrating a state in which the electron beam scans the region of interest (narrow region) in the sample by the deflector to acquire the surface information of the sample in a narrow region according to an embodiment of the present invention.

After obtaining the sample surface information in a wide area by the movement of the sample scanner, the sample is fixed as shown in FIG. 6 to obtain sample surface information of a narrow region in the sample such as the ROI, By controlling the irradiating direction of the charged particle beam in the sample by controlling the sample, information on the sample surface in a narrow region can be precisely obtained as an image of the electron microscope.

Meanwhile, the present invention provides an image for obtaining an optical image of a sample, which is reflected by the mirror in a downward direction of the mirror, between the aperture and the sample in the scanning electron microscope, Acquiring sample surface information of the wide area by providing a detection device; Obtaining an optical image of a sample reflected by the mirror in a downward direction of the mirror by a mirror at a previous or a subsequent stage of the optical image, It is advantageous to obtain an image of a large area of the sample more quickly by comparing or overlapping with the electron microscope image of the sample obtained through the movement of the sample scanner.

In addition, the position of the region of interest in the sample can be easily grasped based on the optical image or the optical image of the sample and the electron microscope image of the large region of the sample, and after the sample is fixed as a subsequent process, So that the sample surface information of the region of interest (narrow region) can be acquired quickly and easily.

FIG. 8 is a diagram illustrating an image obtained by allowing an electron beam to scan a large area in a sample by moving a sample scanner in a state where an electron beam is fixed, (Bottom) showing the image obtained by scanning the region of interest (within the rectangle) in the sample with the electron beam adjusted by the deflector to obtain an image of the region.

8, the present invention includes a sample scanner between a sample and a sample stage, fixes the irradiation direction of the electron beam and controls the movement of the sample scanner, (Lower portion of FIG. 8) of the specimen can be obtained more easily and quickly by scanning the electron beam into the region of interest of the sample Giving.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the following claims. .

10: electron beam source 20: focusing lens group
22: intermediate focusing lens 24: objective lens
30: Vacuum chamber 35: Aperture
37: diaphragm in aperture 40: deflector
50: sample stage 55: sample
56: sample scanner 60: optical axis
91: optical lens 92: optical detector
100: secondary electron detector

Claims (14)

An electron beam source that emits an electron beam;
At least one intermediate focusing lens provided at the electron beam source side for focusing the electron beam and an objective lens provided at the sample side as a final focusing lens and forming an electron beam spot focused on the sample;
A vacuum chamber having an electron beam source and a focusing lens group therein and having an aperture which is a passage through which the electron beam emitted from the electron beam source is irradiated to the sample through the objective lens;
At least one deflector for controlling and changing the irradiation direction of the electron beam; And
A sample scanner supporting the sample to be observed and capable of finely moving the sample horizontally; And a sample stage provided below the sample scanner and capable of horizontally moving the sample and the sample scanner together, the scanning electron microscope comprising:
Wherein the scanning electron microscope is divided into a first region inside the vacuum chamber and a second region having a relatively higher pressure than the first region and including the sample,
Wherein a range in which the sample scanner can move horizontally is smaller than a horizontally movable range of the sample stage, whereby the area to be irradiated with the electron beam can be finely adjusted. The method according to claim 1,
Wherein the size of the aperture is less than 3000 um in diameter. The method according to claim 1,
Wherein said aperture is an aperture in the form of a hole, said first area and said second area being open to each other through said aperture. The method according to claim 1,
Wherein the aperture is formed as a diaphragm having a thickness of not more than 2000 nm through which an electron beam can be transmitted so that the first region is isolated from the second region. The method according to claim 1,
And the electron beam passes through the center of the objective lens, thereby reducing the aberration. The method according to claim 1,
Wherein the pressure difference between the first region and the second region represents a pressure difference of at least 100 times. The method according to claim 1,
Wherein the horizontally movable range of the sample scanner is in the range of 1000 [mu] m to 5 nm. The method according to claim 1,
Wherein the sample scanner is driven by a piezoelectric motor. The method according to claim 1,
And an image detecting device for obtaining an optical image of a sample reflected by the mirror in a downward direction of the mirror, the mirror having an image of the sample to be reflected between the aperture and the sample, Scanning electron microscope. 10. The method of claim 9,
The scanning electron microscope is provided with a separate plate including holes through which electron beams can pass, at the lower part of the aperture, and a mirror is provided under the plate,
Or the scanning electron microscope has an aperture integrated with an objective lens, and a mirror is provided around the aperture at the lower end of the objective lens integrated with the aperture. 10. The method of claim 9,
Wherein the mirror is positioned perpendicular to the optical axis of the electron beam. A method for observing a sample using the scanning electron microscope according to any one of claims 1 to 11. An electron beam source that emits an electron beam;
At least one intermediate focusing lens provided at the electron beam source side for focusing the electron beam and an objective lens provided at the sample side as a final focusing lens and forming an electron beam spot focused on the sample;
A vacuum chamber having an electron beam source and a focusing lens group therein and having an aperture which is a passage through which the electron beam emitted from the electron beam source is irradiated to the sample through the objective lens;
At least one deflector for controlling and changing the irradiation direction of the electron beam;
A sample scanner supporting the sample to be observed and capable of finely moving the sample horizontally; And a sample stage provided under the sample scanner and capable of horizontally moving the sample and the sample scanner together,
A first region inside the vacuum chamber, and a second region having a pressure relatively higher than that of the first region and including the sample,
The method of observing a sample using a scanning electron microscope capable of finely adjusting an area to be irradiated with an electron beam by having a range in which the sample scanner can move horizontally is smaller than a horizontally movable range of the sample stage,
Setting and maintaining a pressure in each of the regions so that the pressure in the first region, which is the inner region of the vacuum chamber, has a pressure that is relatively lower than the pressure in the second region including the sample;
Acquiring sample surface information of a wide area by irradiating the electron beam while fixing the electron beam in a sample direction and moving the sample through the movement of the sample scanner; And
By controlling the irradiation direction of the electron beam beam in the sample by controlling the at least one deflector after fixing the sample in order to obtain the surface information of the sample in the narrow area to be desired based on the obtained sample surface information of the wide area, And obtaining the sample surface information of the sample by using a scanning electron microscope. 14. The method of claim 13,
The scanning electron microscope has an image detecting device for obtaining an optical image of a sample reflected by the mirror in a downward direction of the mirror, the mirror having a mirror between which an image of the sample can be reflected, between the aperture and the sample ,
Obtaining sample surface information of the wide area; Characterized in that the step of obtaining an optical image of a sample reflected by said mirror at a previous, or later, stage of said sample is added.
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