Multi-mode low-voltage electron microscope

Abstract

The present invention relates to a multimode low voltage electron microscope, comprising an electron beam source (1) for generating a primary electron beam (12) operating in an accelerating voltage range of 3-50 kV and comprising, in the following order based on the direction of the primary electron beam (12), a first magnetostatic condenser lens means (3), a second magnetostatic condenser lens means (4), a condenser lens aperture (5), a sample holder (6), a magnetostatic objective lens means (7), an objective lens aperture (8), a first electrostatic projection lens means (9), a detection screen (11), and an edge detection system (18) comprising at least one detector selected from a STEM detector (23) configured to detect a signal of transmitted electrons, a TEM detector configured to detect a signal of a transmitted signal, and / or an ED detector configured to detect a signal of diffracted electrons.

Description

Technical Field

[0001] The present invention relates to a multi-mode low-voltage electron microscope that enables EDS analysis of samples and at least one of STEM, TEM, ED, and SEM analysis. The present invention further relates to a configuration of an electron microscope and an EDS detector for detecting signals of energy-dispersive X-ray radiation in the electron microscope.

Background Art

[0002] For the purposes of the present disclosure, the following abbreviations are explained here. SEM (scanning electron microscope), STEM (scanning transmission electron microscope), TEM (transmission electron microscope), ED (electron diffraction), EDS which is equivalent to EDX (energy-dispersive X-ray spectroscopy), sCMOS (scientific complementary metal-oxide semiconductor), AES (atomic emission spectroscopy), EELS (electron energy loss spectroscopy), BSE (backscattered electron), EM (electromagnetic), ES (electrostatic), MS (magnetostatic).

[0003] Conventional TEM designs are associated with increasing requirements for space and conditions, high energy consumption, and consumption of support media, mainly cooling water. Their installation is complex and often requires installation work. In many cases, electromagnetic components such as electromagnetic coils used together with magnetic pole pieces have conventionally been used in transmission electron microscopes for focusing and magnification and require an external cooling system that requires space. Therefore, their operation is limited to special laboratories and imposes a large load on the environment.

[0004] Lower electron energies (e.g., less than 30 kV) in a low-voltage electron microscope are known to often avoid sample damage, increase the robustness of the microscope, enable miniaturization of the overall apparatus, and reduce its sensitivity to vibrations. Similarly, since the electrostatics and magnetostatics of the electron microscope do not generate any heat loss, in contrast to the electromagnetic optics used conventionally, cooling is avoided and further miniaturization is enabled. However, the trend towards further miniaturization is hampered by other design aspects such as the need to place the detector and the optical system together in positions required for good detection efficiency.

[0005] Furthermore, in electron microscopes, there is another trend to provide electron microscopes that enable multiple analysis modes to be possible simultaneously or at least within the same microscope, in order to utilize the potential analysis results of a given sample while reducing the time and equipment required for such analysis.

[0006] Furthermore, insulating the optical system from the microscope's ancillary electronics and its adverse effects on analysis are also causing problems in the miniaturization of electron microscopes.

[0007] A multi-mode low-voltage electron microscope that operates in an acceleration voltage range of 10 to 25 kV and enables STEM, TEM, and ED sample analysis is known as the LVEM25 (manufactured by DELONG). Since an acceleration voltage of 25 kV is used for TEM analysis and an acceleration voltage of 10 to 15 kV is used for STEM analysis, sufficient beam transmission to the sample, good imaging characteristics, higher contrast, and the possibility of analyzing both stained and unstained samples are ensured. This is equipped with a static magnetic condenser lens, a static magnetic objective lens, and an electrostatic projection lens, removing the need to cool these lenses and resulting in a compact microscope. Each static magnetic lens, namely the static magnetic condenser lens and the static magnetic objective lens, is equipped with at least one permanent magnet and at least one magnetic pole piece to generate the magnetic field of the static magnetic lens. Each electrostatic lens, namely the electrostatic projection lens, is equipped with at least one shaped electrode connected to a power supply voltage or a ground potential to generate the electric field of the electrostatic lens. The electron beam source is a 25 kV Schottky field emission gun that provides high brightness and high-contrast spatial coherence. The sample stage can be accurately moved by a piezoelectric actuator controlled by a joystick. The combination of a diaphragm pump and a turbo molecular pump ensures maintenance-free operation for a long time, and an ion getter pump provides a vibration-free environment. The TEM mode uses an sCMOS camera as a detector. The drawback of the LVEM25 microscope is the absence or addition of a detection mode.

[0008] A similar multi-mode low-voltage electron microscope that operates at an acceleration voltage of 5 kV and enables SEM, STEM, TEM, and ED sample analysis is known as the LVEM5 (manufactured by DELONG). The LVEM5 microscope differs from the above-mentioned LVEM25 microscope in that the electron beam source is a 5 kV Schottky field emission gun and provides an acceleration voltage of 5 kV for SEM, STEM, and TEM analysis. The TEM mode uses an sCMOS camera as a detector, and the SEM mode uses a detector for backscattered electrons. The drawback of the LVEM5 microscope is the absence or addition of a detection mode.

[0009] Another multi-mode electron microscope is disclosed in Patent Document 1, and SEM, STEM, EDX, AES, EELS, Auger spectroscopy, and quantitative / qualitative elemental analysis modes are possible. This operates at an acceleration voltage of less than 40 kV (e.g., 30 kV or 5 kV) in SEM and STEM modes, ensuring high contrast and electron beam stability and avoiding charge accumulation and sample damage. This document also discloses the transmission electron microscope used in the comparative example. The drawbacks of the microscope disclosed in Patent Document 1 are the absence of a detection mode or the addition of a detection mode. Furthermore, the embodiments of EDX detection are not sufficiently disclosed with respect to structural features.

[0010] An EDX detector including a collimator has conventionally been provided in a microscope chamber, which requires very high accuracy to direct the collimator so as to detect as much as possible of the desired signal generated from the sample and, at the same time, as little as possible of the parasitic signal not generated from the sample. In the trend of miniaturization of the microscope chamber or when another detector such as an SEM detector is present nearby, the importance of the accuracy aspect increases.

[0011] Furthermore, related multi-mode electron microscopes are disclosed in Patent Document 2 (SEM, STEM, and TEM modes, acceleration voltage not described) and Patent Document 3 (SEM, STEM, and TEM modes, acceleration voltage is 100 - 120 kV and can be lowered to 50 kV).

[0012] As can be seen from the above, known multimode electron microscopes operating in an acceleration voltage range of less than 50 kV enable sample analysis only in a specific mode, which is either STEM, TEM, and ED mode, or SEM, STEM, and EDX mode. Based on the prior art, there is a need to provide a multimode electron microscope operating in an acceleration voltage range of less than 50 kV that combines more analysis modes and provides sample analysis in these modes essentially (almost or actually) simultaneously. Furthermore, it is necessary to provide the configuration of the EDS detector and the electron microscope so as to detect as many desired signals generated from the sample as possible and, at the same time, as few parasitic signals not generated from the sample as possible.

Prior Art Documents

Patent Documents

[0013]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0014] Therefore, an object of the present invention is to provide a multimode electron microscope that operates in an acceleration voltage range of 3 to 50 kV and combines the EDS mode with at least one of STEM, TEM, ED, and optionally the SEM mode.

Means for Solving the Problems

[0015] In a first aspect of the present invention, the above object is achieved by a multi-mode low-voltage electron microscope as set forth in independent claim 1 and dependent claims 2 to 13. The electron microscope operates in an acceleration voltage range of 3 to 50 kV, for example, 5 kV, 10 kV, 15 kV, 20 kV, 25 kV or 30 kV, and based on the direction of the primary electron beam, in the following order: an electron beam source for generating a primary electron beam, a first static magnetic condenser lens means, a second static magnetic condenser lens means, a condenser lens aperture, a sample holder, a static magnetic objective lens means, an objective lens aperture, a first electrostatic projection lens means, and an end detection system. The second static magnetic condenser lens means and the static magnetic objective lens means both comprise a first objective lens pole piece and a second objective lens pole piece, and a sample holder is disposed between the respective first objective lens pole piece and the second objective lens pole piece.

[0016] The end detection system comprises at least one detector selected from a detection screen (generally shown as a fluorescent screen for TEM applications or a scintillator screen for SEM applications), a STEM detector configured to detect a signal of transmitted electrons, a TEM detector configured to detect a signal of transmitted electrons, and / or an ED detector configured to detect a signal of diffracted electrons.

[0017] The concept underlying the present invention is that an EDS detector configured to detect an energy-dispersive X-ray emission signal (EDS signal) is disposed between a first objective lens pole piece and a second objective lens pole piece, essentially in the same plane and laterally with respect to the sample holder. The EDS detector comprises a collimator attached to the second objective lens pole piece. It is understood herein that "attached" means mechanical attachment. The advantage of attaching the collimator to the second objective lens pole piece instead of attaching the collimator to an EDS detector further provided in the microscope chamber is that it is an easier, more flexible, and more accurate way to provide all the structural elements necessary for EDS detection. Importantly, such an advantage enables miniaturization of the entire immersion objective lens and, consequently, miniaturization of the entire electron microscope. The EDS detector having a collimator according to the present invention is robust enough to provide a sufficiently noise-free EDS signal generated from a sample in a miniaturized immersion objective lens assembly.

[0018] Generally, a collimator is attached to an EDS detector provided in a microscope chamber and serves to limit the incidence of EDS signals not directly generated from the sample to the detector. The collimator typically has a tubular shape, i.e., a housing with at least two (usually two) open ends, and is usually made of a single-element material such as zirconium, gold, or pure graphite, from which spectral lines can be easily subtracted in analysis.

[0019] The first and second static magnetic condenser lens means function to change the characteristics of the optical signal in the end detection system. As is generally known from the prior art, each static magnetic condenser lens means includes at least one permanent magnet and at least one magnetic pole piece to generate the magnetic field of the static magnetic condenser lens. Similarly, as is known from the prior art, the static magnetic objective lens means includes at least one permanent magnet and at least one magnetic pole piece to generate the magnetic field of the static magnetic objective lens. Together with the assembly of permanent magnets, the first and second objective lens pole pieces generate a strong magnetic field in the immersion objective lens. The magnetic field of the immersion objective lens has two parts. The front part of the sample functions as the second static magnetic condenser lens, and the rear part of the sample functions as the static magnetic objective lens. The condenser lens aperture can be embodied as a condenser lens multi-aperture sheet including a plurality of condenser lenses with different diameters. Similarly, the objective lens aperture can be embodied as an objective lens multi-aperture sheet including a plurality of objective lenses with different diameters. The first electrostatic projection lens means functions to magnify the image and its projection on the detection screen. As is generally known from the prior art, the first electrostatic projection lens means includes at least one shaped electrode connected to the power supply voltage or the ground potential to generate the electric field of the electrostatic projection lens.

[0020] As an example, the acceleration voltage can be 25 kV in TEM mode, 10 or 15 kV in STEM / SEM mode, and 10, 15 or 25 kV in EDS mode. The different detection modes are achieved by different processing and parameters of the primary electron beam.

[0021] Preferably, the multi-mode low-voltage electron microscope is configured to detect the signal of the backscattered electrons (BSE) and includes an SEM detector disposed between the first objective lens pole piece and the sample holder.

[0022] Preferably, the TEM detector and the ED detector are constructed as a combined TEM / ED detector equipped with a camera. In order to switch between these modes, it is necessary to refocus the rear focal plane where the diffraction signal is detected by means of an electrostatic projection lens. Preferably, the STEM detector is equipped with a photomultiplier tube.

[0023] Preferably, the STEM detector and / or the TEM detector are configured to detect transmitted electrons in the bright-field detection mode and the dark-field detection mode. In the case of the TEM mode, the bright-field detection mode and the dark-field detection mode are switched by the tilt of the beam and the subsequent selection of an appropriate diffracted beam. In the case of the STEM mode, the bright-field detection mode and the dark-field detection mode are switched by changing the position of the aperture of the detector.

[0024] Preferably, the multi-mode low-voltage electron microscope is equipped with a tilt mirror arranged in the end detection system between the detection screen and the STEM, TEM and ED detectors. By means of the tilt mirror, the optical signal generated by the detection screen passes through the TEM and / or ED detector at the first position and the STEM detector at the second position. As a result, there is no longer a need to move the detector with high requirements when changing the mode.

[0025] Preferably, the sample holder is adjustable in the vertical direction.

[0026] Preferably, the multi-mode low-voltage electron microscope is equipped with electrostatic condenser lens means arranged between the electron beam source and the first Static magnetism condenser lens means. The electrostatic condenser lens means are adjustable and, as is generally known from the prior art, the electrostatic condenser lens means comprise at least one shaped electrode connected to a power supply voltage or a ground potential in order to generate the electric field of the electrostatic condenser lens.

[0027] Preferably, the multi-mode low-voltage electron microscope comprises second electrostatic projection lens means disposed between the first electrostatic projection lens means and the end detection system. The second electrostatic projection lens means enables an increase in the magnification range and, as is generally known from the prior art, the second electrostatic projection lens means comprises at least one shaping electrode connected to a power supply voltage or a ground potential to generate the electric field of the electrostatic projection lens.

[0028] Preferably, the end detection system comprises an optical objective lens disposed between the detection screen and at least one detector or, if a tilt mirror is present, between the detection screen and the tilt mirror. The optical objective lens ensures a reduction in sensitivity to unwanted vibrations and the associated electromagnetic interference with electronic equipment. Further, the optical objective lens ensures that the signal of the transmitted electrons reaches the STEM and / or TEM detector.

[0029] Preferably, the multi-mode low-voltage electron microscope comprises integrated control electronics and a high-voltage power supply as well as cooling means such as one or more fans. The remainder of the electron microscope (i.e., the column with the features specified in the previous paragraph) is electromagnetically shielded by a magnetic shield from the control electronics and the high-voltage power supply and the cooling means, and / or thermally shielded by a thermal shield from the control electronics and the high-voltage power supply and the cooling means, and / or vibrationally shielded by a cooling means damper and / or a column damper and / or a camera damper from the control electronics and the high-voltage power supply and the cooling means. The microscope is preferably at least partially shielded by an X-ray shield, especially comprising a camera damper. In particular, the microscope column comprising an EDS detector is shielded by an X-ray shield to protect the operator from X-ray radiation.

[0030] Furthermore, zone power control of the control electronics, high voltage power supply, and cooling means can be provided to prevent heat transfer to the remaining part of the electron microscope (i.e., the column). A heat shield that conducts heat from the electronics and a system of zone thermal control can connect the column and the electronics in a single structure, thus saving more space.

[0031] Preferably, the multi-mode low voltage electron microscope is configured to generate a vacuum and includes an ion pump integrally coupled with at least one recovery baking element connected to a baking unit for automatic vacuum recovery (e.g., after transportation or vacuum breakage). The baking unit controls the heating and supplies power to the ion pump by at least one recovery baking element disposed integrally with the ion pump, whereby the microscope can be easily operated for several hours. By heating the ion pump, adsorbed molecules (usually water from moisture in the air) are released from each inner surface, and then these molecules are discharged by the ion pump. Since only a part of the microscope is heated, the baking unit refers to a soft baking function. The recovery baking element disposed integrally with the ion pump operates at a low safety voltage with accurately defined power, so temperature sensor adjustment is not required and the system is simple and robust.

[0032] In a second aspect of the present invention, the above object is achieved by a configuration of an electron microscope and an EDS detector for detecting a signal of energy-dispersive X-ray radiation in the electron microscope according to independent claim 14. The electron microscope generally includes an objective lens pole piece, and the EDS detector includes a collimator attached to the objective lens pole piece. The advantages of such an arrangement have been described above, and it is intended to provide an EDS detection mode, which is also applicable to other electron microscopes having a general objective lens pole piece. As an example, the collimator can be attached to the objective lens pole piece behind the sample holder based on the direction of the primary electron beam, such as in a multi-mode low-voltage electron microscope according to the present invention. As another example, the collimator can be attached to the objective lens pole piece in front of the sample holder based on the direction of the primary electron beam in a scanning electron microscope having a sample holder generally arranged behind the objective lens pole piece.

Brief Description of the Drawings

[0033]

Figure 1

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Figure 3b

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Figure 5

Embodiments for Carrying Out the Invention

[0034] The optical diagram of a conventional transmission electron microscope is shown in FIG. 1A. For clarity purposes, this figure is shown upside down compared to the actual microscope. The TEM includes, in the order based on the direction of the primary electron beam (from bottom to top), an electron beam source 101 for generating the primary electron beam, electromagnetic condenser lens means 102, a sample holder 106 for holding the sample, electromagnetic objective lens means 107, an objective lens aperture 108, an assembly of intermediate lens means 109, electromagnetic projection lens means 110, and a detection screen 111. Each electromagnetic element generates unwanted heat and requires cooling, which is often difficult due to spatial requirements.

[0035] The optical diagrams of the electron microscope according to the present invention and a prior art electron microscope called LVEM25 (manufactured by DELONG) are shown in FIG. 1B. The electron microscope includes, in the order based on the direction of the primary electron beam 12 (from bottom to top, the beam 12 is also shown in FIG. 2), an electron beam source 1 for generating the primary electron beam 12, electrostatic condenser lens means 2, first static magnetic condenser lens means 3, second static magnetic condenser lens means 4, a condenser lens aperture 5, a sample holder 6 for holding the sample, static magnetic objective lens means 7, an objective lens aperture 8, first electrostatic projection lens means 9, second electrostatic projection lens means 10, and a detection screen 11. Since the electrostatic and static magnetic elements do not generate unwanted heat, there is no need for cooling, which can advantageously lead to miniaturization of the microscope.

[0036] The detailed configuration of various detectors of the electron microscope according to the present invention is shown in FIG. 2. Both the second static magnetic condenser lens means 4 and the static magnetic objective lens means 7 include a first objective lens pole piece 13 (lower part) and a second objective lens pole piece 14 (upper part). The sample holder 6 is disposed between the objective lens pole pieces 13, 14, and these objective lens pole pieces 13, 14 generate a strong two - part magnetic field in the immersion objective lens together with an assembly of permanent magnets. The front part of the sample holder 6 functions as the second static magnetic condenser lens, and the rear part of the sample holder 6 functions as the static magnetic objective lens.

[0037] An EDS detector 15 configured to detect signals of energy-dispersive X-ray radiation is disposed between a first objective lens pole piece 13 and a second objective lens pole piece 14. The EDS detector 15 is disposed in a substantially same plane with respect to the sample holder 6 and in a lateral direction (i.e., a side portion of the sample holder 6). The EDS detector 15 itself is attached to the microscope chamber and includes a tubular collimator 16 attached to the second objective lens pole piece 14. Further, an SEM detector 17 configured to detect signals of backscattered electrons is disposed between the first objective lens pole piece 13 and the sample holder 6.

[0038] A detection screen 11 for generating an optical signal 20 includes an optical objective lens 19, a tilt mirror 21, a photomultiplier tube, a STEM detector 23 configured to detect signals of transmitted electrons, and a camera (such as an sCMOS type), and is included in an end detection system 18 together with a composite TEM / ED detector 22 configured to detect signals of transmitted electrons and diffracted electrons. The tilt mirror 21 is disposed between the optical objective lens 19 and the STEM, TEM, and ED detectors 22, 23, thereby enabling the optical signal 20 generated by the detection screen 11 and corrected by the optical objective lens 19 to pass through the TEM / ED detector 22 at a first position and the STEM detector 23 at a second position.

[0039] The results from the analysis of the gallium nitride thin film sample are shown in Figs. 3a - 3k. Figs. 3a and 3b show an overview of the sample and a detailed overview of the sample in TEM mode at a low magnification of 25 kV. Fig. 3c shows a sample portion in TEM bright field mode at 25 kV. Figs. 3d and 3e show sample portions at two different diffraction maxima in TEM dark field mode at 25 kV. Fig. 3f shows the electron diffraction pattern of the sample at 25 kV corresponding to the TEM dark field mode of Figs. 3d and 3e. Fig. 3g shows a sample portion in STEM bright field mode at 15 kV. Fig. 3h shows a sample portion in SEM mode at 15 kV. Figs. 3i, 3j and 3k show sample portions in EDS mode at 15 kV with atomic mapping (Fig. 3i is gallium, Fig. 3j is nitrogen, Fig. 3k is silicon). Fig. 3l shows a graphical representation of the elemental sample analysis in EDS mode at 15 kV, showing characteristic Kα transitions (the peaks are from left to right: a typical peak region for nitrogen at about 0.4 keV, a dominant peak for gallium at about 1.1 keV, a dominant peak for silicon at about 1.7 keV, a dominant peak for gallium at about 9.2 keV).

[0040] An overall view of the electron microscope including the features of the integrated design is shown in Fig. 4. The bottom of the microscope is equipped with control electronics and a high - voltage power supply 29, which generates heat and needs to be cooled by cooling means such as a fan placed in the cooling means damper 25. The microscope column placed in the center must be shielded electromagnetically, thermally and vibrationally from the control electronics and the high - voltage power supply 29 by the magnetic shield 24, the thermal shield 33 and the column damper 26. The camera placed at the top and connected to the control electronics 29 via the cable 30 fixed by the cable clamp 31 is also protected by the camera damper 28. As a whole, the entire microscope has an external acoustic cover 27 and a vibration - resistant fixing block 32. Also, for example, there is an ion pump 34 equipped with a recovery baking element 36 and a baking unit 35 for automatic vacuum recovery after transportation or vacuum breakage.

[0041] An example of an electron microscope is schematically shown in Fig. 5 together with the associated electronic equipment. Only the electronically controlled components of the electron microscope are shown, i.e., permanent magnets that are not electronically controlled are not shown. The electronically controlled components include electron optical components, i.e., a gun chamber connected to conditioning (COND), two ion pumps (IP-A, IP-B), and a sample stage, an aperture stage, a projection section, an octupole, two lenses, a microscope chamber connected to a vacuum gauge, an EDS detector, an ion pump (IP-C), and a turbo molecular pump (TMP). Also included in the electronically controlled components are optical components, i.e., an objective lens, a STEM detector, and a camera (a combined TEM / ED detector). The gun chamber is powered and controlled by a gun high voltage power supply unit. The ion pumps are powered and controlled by an ion pump power supply unit and are further controlled by a baking unit (labeled "soft baking") for automatic vacuum recovery connected to a hardware security unit. The sample stage and the objective lens are powered and controlled by a combined control unit for the sample stage and the objective lens. The aperture stage is powered and controlled by an aperture stage control unit. The lenses are powered and controlled by a high voltage power supply unit. The octupole is powered and controlled by an octupole and scanning control unit and a STEM and scanning control unit. The EDS detector is powered and controlled by an EDS control unit, which in turn controls the STEM and scanning control unit. The STEM detector is powered by a high voltage power supply unit and controlled by a STEM and scanning control unit. All of the above units are further connected to a general power supply unit and a general communication and control system. The camera is also powered by a general power supply unit. The turbo molecular pump and the vacuum gauge are powered by a general power supply unit and controlled by a general communication and control system.The camera, EDS control unit, STEM and scanning control unit, and general communication and control system are digitally connected to a computer.

Industrial Applicability

[0042] The present invention can be used to obtain detailed images and detailed analysis of many samples without the risk of sample damage. Typical applications of this equipment are the analysis of samples from the boundary between life science and materials science, for example, tissue sections with nanomaterials (for diagnostic, therapeutic or research purposes, and for industrial inspection or facility inspection). The TEM mode provides users with high-speed structural analysis, STEM provides deeper insights into the details of the structure, SEM provides basic surface analysis, EDS provides information on chemical composition, and ED provides additional information on crystal structure.

Explanation of Signs

[0043] 1 Electron beam source 2 Electrostatic condenser lens means 3 First static magnetic condenser lens means 4 Second static magnetic condenser lens means 5 Condenser lens aperture 6 Sample holder 7 Static magnetic objective lens means 8 Objective lens aperture 9 First electrostatic projection lens means 10 Second electrostatic projection lens means 11 Detection screen 12 Primary electron beam 13 First objective lens pole piece 14 Second objective lens pole piece 15 EDS detector 16 Collimator 17 SEM detector 18 End detection system 19 Optical objective lens 20 Optical signal 21 Tilt mirror 22 TEM / ED detector 23 STEM detector 24 Magnetic shield 25 Cooling means damper 26 Column damper 27 Acoustic cover 28 Camera damper 29 Control electronics and high voltage power supply 30 Cable 31 Cable clamp 32 Vibration-resistant fixing block 33 Thermal shield 34 Ion pump 35 Baking unit 36 Recovery baking element 101 Electron beam source 102 Electromagnetic focusing lens means 106 Sample holder 107 Electromagnetic objective lens means 108 Objective lens aperture 109 Intermediate lens means 110 Electromagnetic projection lens means 111 Detection screen

Claims

1. Operates in an acceleration voltage range of 3 to 50 kV and, based on the direction of the primary electron beam (12), in the following order, an electron beam source (1) for generating the primary electron beam (12); first static magnetic condenser lens means (3); second static magnetic condenser lens means (4); a condenser lens aperture (5); a sample holder (6); static magnetic objective lens means (7); an objective lens aperture (8); first electrostatic projection lens means (9); a detection screen (11), and an end detection system (18) comprising at least one detector selected from a STEM detector (23) configured to detect a signal of transmitted electrons, a TEM detector configured to detect a signal of the transmitted signal, and / or an ED detector configured to detect a signal of diffracted electrons A multi-mode low-voltage electron microscope comprising: both the second static magnetic condenser lens means (4) and the static magnetic objective lens means (7) comprise a first objective lens pole piece (13) and a second objective lens pole piece (14), between which the sample holder (6) is disposed; an EDS detector (15) configured to detect a signal of energy-dispersive X-ray emission is disposed between the first objective lens pole piece (13) and the second objective lens pole piece (14), and is in a substantially the same plane as and laterally with respect to the sample holder (6); the EDS detector (15) comprises a collimator (16) attached to the second objective lens pole piece (14). A multi-mode low-voltage electron microscope characterized by the above.

2. The multi-mode low-voltage electron microscope according to claim 1, wherein an SEM detector (17) configured to detect a signal of backscattered electrons is disposed between the first objective lens pole piece (13) and the sample holder (6).

3. The multi-mode low-voltage electron microscope according to claim 1 or 2, wherein the TEM detector and the ED detector are constructed as a combined TEM / ED detector (22) comprising a camera.

4. The multi-mode low-voltage electron microscope according to claim 1 or 2, wherein the STEM detector (23) comprises a photomultiplier tube.

5. The multi-mode low-voltage electron microscope according to claim 1 or 2, wherein the STEM detector (23) and / or the TEM detector (22) are configured to detect transmitted electrons in a bright-field detection mode and a dark-field detection mode.

6. The multi-mode low-voltage electron microscope according to claim 1 or 2, wherein the tilting mirror (21) is arranged in the end detection system (18) between the detection screen (11) and the STEM, TEM, and ED detectors (22, 23), so that the optical signal (20) generated by the detection screen (11) passes through the TEM and / or ED detector (22) at a first position and the STEM detector (23) at a second position by the tilting mirror (21).

7. The multi-mode low-voltage electron microscope according to claim 1 or 2, wherein the position of the sample holder (6) is adjustable in the vertical direction.

8. The multi-mode low-voltage electron microscope according to claim 1 or 2, comprising an electrostatic condenser lens means (2) arranged between the electron beam source (1) and the first electrostatic condenser lens means (3).

9. The multi-mode low-voltage electron microscope according to claim 1 or 2, comprising a second electrostatic projection lens means (10) arranged between the first electrostatic projection lens means (9) and the end detection system (18).

10. The multi-mode low-voltage electron microscope according to claim 1 or 2, wherein the end detection system (18) comprises an optical objective lens (19) arranged between the detection screen (11) and at least one detector (22, 23), or between the detection screen (11) and the tilting mirror (21).

11. The multi-mode low-voltage electron microscope further comprises an integrated control electronics and a high-voltage power supply (29) and a cooling means, and the remaining part of the electron microscope is electromagnetically shielded by a magnetic shield (24) from the control electronics and the high-voltage power supply (29) and the cooling means, and / or thermally shielded by a thermal shield (33) from the control electronics and the high-voltage power supply (29) and the cooling means, and / or vibrationally shielded by a cooling means damper (25) and / or a column damper (26) and / or a camera damper (28) from the control electronics and the high-voltage power supply (29) and the cooling means. The multi-mode low-voltage electron microscope according to claim 1 or 2.

12. The multi-mode low-voltage electron microscope according to claim 1 or 2, which is at least partially shielded by an X-ray shield.

13. The multi-mode low-voltage electron microscope is configured to generate a vacuum and includes an ion pump (34) integrally coupled with at least one recovery baking element (36), wherein the recovery baking element (36) is connected to a baking unit (35). The multi-mode low-voltage electron microscope according to claim 1 or 2.

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