Electron microscope

Abstract

Provided is an electron microscope that does not require adjustment of an electron image formation position, even when electrons are accelerated / decelerated. An electron microscope according to the present invention comprises a first transmission lens that transmits electrons according to a fixed condition, an incidence-side electrostatic lens that decelerates or accelerates the electrons transmitted by the first transmission lens, a trajectory alteration part that alters the trajectory of the electrons decelerated or accelerated by the incidence-side electrostatic lens, an emission-side electrostatic lens that decelerates or accelerates the electrons that have had the trajectory thereof altered by the trajectory alteration part, and a second transmission lens that transmits the electrons decelerated or accelerated by the emission-side electrostatic lens according to a fixed condition. The electron microscope is characterized in that the emission-side electrostatic lens has a first lens and a second lens and in that the first lens focuses the electrons that have had the trajectory thereof altered by the trajectory alteration part onto the center point of the second lens.

Description

Electron microscope

[0007] ,

[0001] The present invention relates to an electron microscope that generates an observation image of a sample by detecting electrons emitted from the sample.

[0002] An electron microscope is a device that generates an observation image of a sample by detecting photoelectrons, secondary electrons, reflected electrons, etc. emitted from the sample. To obtain various information related to the sample, the electrons emitted from the sample are identified or the electron distribution is detected.

[0003] Patent Document 1 discloses a scanning electron microscope provided with an emittance analyzer assembly that extracts information related to the emittance of secondary electrons and reflected electrons. The emittance analyzer assembly includes a first electrostatic lens, a first detector, a first mesh, a second mesh, a second electrostatic lens, and a second detector. In the first electrostatic lens, the electrons are accelerated and decelerated and focused, and many reflected electrons are detected by the first detector. Also, a deceleration region for decelerating electrons is formed between the first detector and the first mesh, and a drift region for aligning the polar angles of electrons is formed between the first mesh and the second mesh. Further, in the second electrostatic lens, the electrons are accelerated and decelerated, and mainly secondary electrons are detected by the second detector.

[0004] Japanese Patent No. 6934980

[0005] However, in Patent Document 1, insufficient consideration is given to the change in the imaging conditions for the detector due to the acceleration and deceleration of electrons in the electrostatic lens. That is, when the imaging conditions change due to the acceleration and deceleration of electrons, the imaging position of the electrons changes and the magnification of the observation image also changes, so it takes time to adjust the imaging position of the electrons.

[0006] Therefore, an object of the present invention is to provide an electron microscope that does not require adjustment of the electron imaging position even when there is acceleration and deceleration of electrons.

[0007] To achieve the above objective, the present invention provides an electron microscope comprising: a first transmission lens that transmits electrons under fixed conditions; an incident electrostatic lens that decelerates or accelerates electrons transmitted by the first transmission lens; an orbital change unit that changes the orbit of electrons decelerated or accelerated by the incident electrostatic lens; an exit electrostatic lens that accelerates or decelerates electrons whose orbits have been changed by the orbital change unit; and a second transmission lens that transmits electrons decelerated or accelerated by the exit electrostatic lens under fixed conditions, wherein the exit electrostatic lens has a first lens and a second lens, and the first lens focuses electrons whose orbits have been changed by the orbital change unit to the center point of the second lens.

[0008] According to the present invention, it is possible to provide an electron microscope that does not require adjustment of the electron imaging position even when there is acceleration or deceleration of electrons.

[0009] Figures showing the configuration of the main parts of the electron microscope of the present invention; Figure showing the configuration of an energy analyzer, which is an example of an orbital change unit; Figure showing the configuration of the electron microscope of Embodiment 1; Figure showing the effects of the present invention; Figure showing the configuration of the electron microscope of Embodiment 2; Figure showing the configuration of the electron microscope of Embodiment 3; Figure showing the configuration of the electron microscope of Embodiment 4.

[0010] The following describes embodiments of the electron microscope according to the present invention with reference to the attached drawings. An electron microscope is a device that detects photoelectrons, secondary electrons, backscattered electrons, etc., emitted from a sample to generate an observation image of the sample, such as a PEEM (Photo-Emission Electron Microscope) or a SEM (Scanning Electron Microscope).

[0011] The configuration of the main parts of the electron microscope of the present invention will be explained using Figure 1. The electron microscope of the present invention comprises a first transmission lens 101, an incident electrostatic lens 102, an orbital change unit 103, an exit electrostatic lens 104, and a second transmission lens 105.

[0012] The first transmission lens 101 is a lens that transmits the electron beam 100 and focuses the electron beam 100 without accelerating or decelerating it. The incident electrostatic lens 102 is a lens that focuses the electron beam 100 transmitted by the first transmission lens 101 while decelerating or accelerating it. The trajectory changing unit 103 changes the trajectory of the electron beam 100 that has been decelerated or accelerated by the incident electrostatic lens 102.

[0013] Figure 2 illustrates the configuration of an energy analyzer 200, which is an example of the orbital change unit 103. The energy analyzer 200 consists of two hemispherical electrodes of different radii arranged concentrically, with a higher voltage applied to the inner hemispherical electrode than to the outer hemispherical electrode. Electrons incident on the energy analyzer 200 are deflected hemispherically by the electric field formed between the two hemispherical electrodes and exit from a position rotated 180° from the incident position. The degree of electron deflection depends on the electron's energy, with lower energy electrons being deflected more significantly. For example, when the energy of an electron passing through the center between the two hemispherical electrodes is Ep, electrons with lower energy Ep-ΔE will have their orbits shifted as shown by the dotted line. The amount of orbital shift Δx at the electron's exit position is proportional to ΔE / Ep.

[0014] Therefore, by placing an energy slit 201 having a slit through which electrons pass on the output side of the energy analyzer 200, electrons within a predetermined energy range can be extracted. Since the orbital deviation Δx is inversely proportional to the energy Ep, the energy resolution of the electrons extracted after passing through the energy slit 201 can be improved by decelerating the electrons incident on the energy analyzer 200 and lowering their energy Ep.

[0015] Returning to the explanation of Figure 1, the exit-side electrostatic lens 104 is a lens that focuses the electron beam 100, whose trajectory has been changed by the trajectory change unit 103, while accelerating or decelerating it. When the incident-side electrostatic lens 102 accelerates the electron beam 100, the exit-side electrostatic lens 104 decelerates the electron beam 100, and when the incident-side electrostatic lens 102 decelerates the electron beam 100, the exit-side electrostatic lens 104 accelerates the electron beam 100. The second transmission lens 105 is a lens that transmits the electron beam 100, which has been accelerated or decelerated by the exit-side electrostatic lens 104, and focuses the electron beam 100 without accelerating or decelerating it. The electron beam 100 that exits the second transmission lens 105 is incident on the detector or sample.

[0016] Incidentally, when the electron beam 100 is accelerated or decelerated by the incident electrostatic lens 102 and the exit electrostatic lens 104, the imaging position of the electron beam 100 emitted from the second transmission lens 105 changes. When the electron beam 100 emitted from the second transmission lens 105 is incident on the detector, the change in imaging position changes the magnification of the observed image, so it becomes necessary to adjust the lens intensity of the second transmission lens 105, and this adjustment takes time.

[0017] Therefore, in this invention, the output electrostatic lens 104 is provided with a first lens 104A and a second lens 104B, and the electron beam 100 emitted from the trajectory changing section 103 is focused to the center point of the second lens 104B by the first lens 104A. By focusing the electron beam 100 to the center point of the second lens 104B, the imaging position of the electron beam 100 emitted from the second transmission lens 105 is maintained, so adjustment of the lens intensity of the second transmission lens 105 becomes unnecessary, and a decrease in the throughput of the electron microscope can be suppressed.

[0018] The configuration of the electron microscope in Example 1 will be explained using Figure 3. The electron microscope illustrated in Figure 3 is a PEEM that detects photoelectrons emitted from a sample by light irradiation, and comprises a light source 301, an objective lens 302, an input lens 303, an energy analyzer 200, an output lens 304, a projection lens 305, a detector 306, and a control unit 307.

[0019] The light source 301 emits light that is irradiated onto the sample 300. The light irradiated onto the sample 300 is, for example, an ultraviolet laser, and photoelectrons are emitted from the sample 300 upon irradiation with light.

[0020] The objective lens 302 focuses the photoelectrons emitted from the sample 300 onto the input lens 303. In other words, the objective lens 302 functions as the first transmission lens 101.

[0021] The input lens 303 focuses the photoelectrons emitted from the objective lens 302 while slowing them down. In other words, the input lens 303 functions as the incident electrostatic lens 102.

[0022] The energy analyzer 200 deflects the photoelectrons emitted from the input lens 303 into a hemispherical shape. In other words, the energy analyzer 200 functions as a trajectory changing unit. Furthermore, the energy resolution of the energy analyzer 200 is improved by the deceleration of the photoelectrons by the input lens 303.

[0023] The output lens 304 accelerates and focuses the photoelectrons emitted from the energy analyzer 200. In other words, the output lens 304 functions as the output-side electrostatic lens 104. The acceleration by the output lens 304 is performed in accordance with the deceleration by the input lens 303. That is, if the amount of energy decrease of the photoelectrons at the input lens 303 is ΔE, then the amount of energy increase of the photoelectrons at the output lens 304 is ΔE. The output lens 304 also has a first lens 104A and a second lens 104B, and the first lens 104A focuses the photoelectrons emitted from the energy analyzer 200 to the center point of the second lens 104B.

[0024] The projection lens 305 focuses the photoelectrons emitted from the output lens 304 onto the detector 306. In other words, the projection lens 305 functions as a second transmission lens 105. Since the photoelectrons are focused at the center point of the second lens 104B, the imaging position of the photoelectrons emitted from the projection lens 305 is maintained. That is, readjustment of the lens intensity of the projection lens 305 is unnecessary.

[0025] The detector 306 detects photoelectrons emitted from the projection lens 305 and outputs a detection signal to the control unit 307.

[0026] The control unit 307 is a device that controls each part, and is, for example, a general-purpose computer. The computer is equipped with a processor such as a CPU (Central Processing Unit) and memory such as RAM (Random Access Memory) and ROM (Read Only Memory). The control unit 307 also generates an observation image of the sample 300 based on the detection signal output from the detector 306.

[0027] According to the electron microscope illustrated in Figure 3, even when there is acceleration or deceleration of photoelectrons by the input lens 303 and output lens 304, it is not necessary to readjust the projection lens 305, thus suppressing a decrease in the throughput of the electron microscope.

[0028] The effects of the present invention will be explained using Figure 4. Figure 4 illustrates an observation image of a sample with multiple circular protrusions arranged in a row. The upper panel shows an observation image using a conventional electron microscope, and the lower panel shows an observation image using the electron microscope of the present invention. The left side shows the case without electron acceleration or deceleration, and the right side shows the case with electron acceleration or deceleration and without readjustment of the projection lens 305.

[0029] In conventional electron microscopes, the acceleration and deceleration of electrons changes the imaging position of the electrons, resulting in a change in the magnification of the observed image and rotation of the image. Correcting the changes in magnification and rotation of the observed image requires readjustment of the projection lens 305. The rotation of the observed image is a result of the projection lens 305 being a magnetic lens.

[0030] In contrast, in the electron microscope of the present invention, even when electrons are accelerated or decelerated, there is no change in the magnification or rotation of the observed image. Therefore, it is not necessary to readjust the projection lens 305, and thus the decrease in the throughput of the electron microscope can be suppressed.

[0031] The configuration of the electron microscope in Example 2 will be explained using Figure 5. The electron microscope illustrated in Figure 5 is a SEM that detects signal electrons such as secondary electrons and backscattered electrons emitted from a sample by irradiation with an electron beam, and comprises an objective lens 501, a deflector 502, an E×B deflector 503, a focusing lens 504, an incident electrostatic lens 102, an aperture 505, an exit electrostatic lens 104, a projection lens 506, a detector 507, and a control unit 508.

[0032] An electron beam emitted from an electron source (not shown) passes through an E×B deflector 503, is deflected by a deflector 502, focused by an objective lens 501, and then irradiates the sample 500. Irradiation with the electron beam causes the sample 500 to emit signal electrons such as secondary electrons and backscattered electrons.

[0033] The objective lens 501 focuses the signal electrons emitted from the sample 500. In other words, the objective lens 501 functions as the first transmission lens 101. The signal electrons emitted from the objective lens 501 are deflected toward the focusing lens 504 by the E×B deflector 503.

[0034] The focusing lens 504 focuses the signal electrons deflected by the E×B deflector 503. In other words, the focusing lens 504 functions as the first transmission lens 101.

[0035] The incident electrostatic lens 102 focuses the signal electrons that have been focused by the focusing lens 504 while accelerating and decelerating them.

[0036] The aperture 505 has holes through which signal electrons pass. Only signal electrons that pass through the holes in the aperture 505 head towards the exit-side electrostatic lens 104. In other words, the aperture 505 functions as a trajectory changing unit 103 that changes the trajectory of signal electrons. The opening angle of the signal electrons in the aperture 505 changes due to acceleration and deceleration by the incident-side electrostatic lens 102. For example, when the signal electrons are accelerated by the incident-side electrostatic lens 102, the opening angle of the signal electrons in the aperture 505 becomes smaller.

[0037] The exit-side electrostatic lens 104 focuses the signal electrons that have passed through the aperture 505 while accelerating and decelerating them. When the incident-side electrostatic lens 102 accelerates the signal electrons, the exit-side electrostatic lens 104 decelerates them, and when the incident-side electrostatic lens 102 decelerates the signal electrons, the exit-side electrostatic lens 104 accelerates them. The exit-side electrostatic lens 104 also has a first lens 104A and a second lens 104B, and the first lens 104A focuses the signal electrons that have passed through the aperture 505 to the center point of the second lens 104B.

[0038] The projection lens 506 focuses the signal electrons emitted from the exit-side electrostatic lens 104 onto the detector 507. In other words, the projection lens 506 functions as a second transmission lens 105. Since the signal electrons are focused at the center point of the second lens 104B, the image position of the signal electrons emitted from the projection lens 506 is maintained. That is, readjustment of the lens intensity of the projection lens 506 is unnecessary.

[0039] The detector 507 detects the signal electrons emitted from the projection lens 506 and outputs the detection signal to the control unit 508.

[0040] The control unit 508 is, for example, a general-purpose computer, which controls each part and generates an observation image of the sample 500 based on the detection signal output from the detector 507.

[0041] According to the electron microscope illustrated in Figure 5, the opening angle of the signal electrons at the aperture 505 can be changed by accelerating and decelerating the incident electrostatic lens 102, so that it is possible to adjust what emission angle of signal electrons emitted from the sample 500 is detected. For example, if the signal electrons are decelerated by the incident electrostatic lens 102, signal electrons with a large emission angle from the sample 500 cannot pass through the aperture 505, and only signal electrons with a small emission angle from the sample 500 can be detected by the detector 507.

[0042] Also, even when there is acceleration and deceleration by the incident-side electrostatic lens 102, since the first lens 104A focuses the signal electrons that have passed through the aperture 505 at the center point of the second lens 104B, it is not necessary to readjust the projection lens 506, and a reduction in the throughput of the electron microscope can be suppressed.

[0043] The configuration of the electron microscope according to Embodiment 3 will be described using FIG. 6. The electron microscope illustrated in FIG. 6 is a SEM, and includes an electron gun 601, an extraction electrode 602, an acceleration electrode 603, a first condenser lens 604, an incident-side electrostatic lens 102, an aperture 605, an exit-side electrostatic lens 104, a second condenser lens 606, a deflector 607, an objective lens 608, a detector 609, and a control unit 610.

[0044] The electron gun 601 emits an electron beam that irradiates the sample 600. The extraction electrode 602 forms an electric field for extracting the electron beam from the electron gun 601. The acceleration electrode 603 forms an electric field for accelerating the electron beam.

[0045] The first condenser lens 604 focuses the electron beam that has been emitted from the electron gun 601 and accelerated. That is, the first condenser lens 604 functions as the first transfer lens 101.

[0046] The incident-side electrostatic lens 102 focuses the electron beam that has been focused by the first condenser lens 604 while accelerating and decelerating it.

[0047] The aperture 605 has a hole through which the electron beam passes. Only the electron beam that has passed through the hole of the aperture 605 heads toward the exit-side electrostatic lens 104. That is, the aperture 605 functions as the trajectory changing unit 103 that changes the trajectory of the electron beam. Note that due to the acceleration and deceleration by the incident-side electrostatic lens 102, the opening angle of the electron beam at the aperture 605 changes. For example, when the electron beam is accelerated by the incident-side electrostatic lens 102, the opening angle of the electron beam at the aperture 605 becomes smaller.

[0048] The output-side electrostatic lens 104 focuses the electron beam passing through the aperture of the aperture stop 605 while accelerating or decelerating it. When the incident-side electrostatic lens 102 accelerates the electron beam, the output-side electrostatic lens 104 decelerates the electron beam, and when the incident-side electrostatic lens 102 decelerates the electron beam, the output-side electrostatic lens 104 accelerates the electron beam. The output-side electrostatic lens 104 has a first lens 104A and a second lens 104B, and the first lens 104A focuses the electron beam passing through the aperture stop 505 on the center point of the second lens 104B.

[0049] The second condenser lens 606 focuses the electron beam emitted from the output-side electrostatic lens 104. That is, the second condenser lens 606 functions as the second transfer lens 105.

[0050] The deflector 607 deflects the electron beam. The position of the electron beam irradiated on the sample 600 is controlled by the deflection of the electron beam by the deflector 607.

[0051] The objective lens 608 focuses the electron beam deflected by the deflector 607 on the sample 600. That is, the objective lens 608 functions as the second transfer lens 105 together with the second condenser lens 606. Since the electron beam is focused on the center point of the second lens 104B by the first lens 104A, the imaging position of the electron beam emitted from the objective lens 608 is maintained. That is, readjustment of the lens strength of the second condenser lens 606 and the objective lens 608 is not required. Also, signal electrons such as secondary electrons and reflected electrons are emitted from the sample 600 by the irradiation of the electron beam.

[0052] The detector 609 detects the signal electrons emitted from the sample 600 and outputs a detection signal to the control unit 610.

[0053] The control unit 610 is, for example, a general-purpose computer, controls each part, and generates an observation image of the sample 600 based on the detection signal output from the detector 609.

[0054] According to the electron microscope illustrated in Figure 6, the opening angle of the electron beam at the aperture 605 can be changed by accelerating and decelerating the incident electrostatic lens 102, thereby adjusting the opening angle of the electron beam irradiated onto the sample 500. For example, if the electron beam is decelerated by the incident electrostatic lens 102, electron beams with a large opening angle cannot pass through the aperture 605, and the opening angle of the electron beam irradiated onto the sample 500 becomes smaller.

[0055] Furthermore, even when acceleration or deceleration occurs due to the incident electrostatic lens 102, the first lens 104A focuses the electron beam that has passed through the aperture 605 onto the center point of the second lens 104B, eliminating the need to readjust the second condenser lens 606 and the objective lens 608. As a result, a decrease in the throughput of the electron microscope can be suppressed.

[0056] The configuration of the electron microscope in Example 4 will be explained using Figure 7. The electron microscope illustrated in Figure 7 is a SEM that irradiates the sample with an electron beam at an angle. When the electron beam is irradiated at an angle, the electron beam deviates from the axis center of the objective lens, causing off-axis aberration. Therefore, by selecting an electron beam with a large aberration from the electron beam emitted from the electron gun and irradiating the sample with it, the off-axis aberration generated in the objective lens is canceled out. The electron microscope illustrated in Figure 7 comprises an electron gun 701, an extraction electrode 702, an accelerating electrode 703, a first condenser lens 704, an aperture 705, a second condenser lens 706, a deflector 707, an objective lens 708, a detector 709, and a control unit 710.

[0057] The electron gun 701 emits an electron beam that is irradiated onto the sample 700. The extraction electrode 702 forms an electric field to extract the electron beam from the electron gun 701. The accelerating electrode 703 forms an electric field to accelerate the electron beam.

[0058] The first condenser lens 704 focuses the electron beam emitted and accelerated from the electron gun 701. In other words, the first condenser lens 704 functions as the first transmission lens 101.

[0059] The incident electrostatic lens 102 focuses the electron beam, which has been focused by the first condenser lens 704, while accelerating and decelerating it.

[0060] The aperture 705 has an opening through which the electron beam passes. Only the electron beam that passes through the opening in the aperture 705 heads towards the exit-side electrostatic lens 104. Since the aperture 705 is positioned to cover the central axis of the electro-optical lens barrel, only electron beams with large aberrations head towards the exit-side electrostatic lens 104. In other words, the aperture 705 functions as a trajectory changing unit 103 that changes the trajectory of the electron beam. The opening angle of the electron beam at the aperture 705 changes due to acceleration and deceleration by the incident-side electrostatic lens 102. For example, when the electron beam is accelerated by the incident-side electrostatic lens 102, the opening angle of the electron beam at the aperture 705 decreases.

[0061] The exit-side electrostatic lens 104 focuses the electron beam as it passes through the aperture 705, accelerating and decelerating it as it goes. When the incident-side electrostatic lens 102 accelerates the electron beam, the exit-side electrostatic lens 104 decelerates it, and when the incident-side electrostatic lens 102 decelerates the electron beam, the exit-side electrostatic lens 104 accelerates it. The exit-side electrostatic lens 104 also has a first lens 104A and a second lens 104B, with the first lens 104A focusing the electron beam that has passed through the aperture 505 onto the center point of the second lens 104B.

[0062] The second condenser lens 706 focuses the electron beam emitted from the exit-side electrostatic lens 104. In other words, the second condenser lens 706 functions as a second transmission lens 105.

[0063] The deflector 707 deflects the electron beam. The deflection of the electron beam by the deflector 707 controls the position of the electron beam irradiated onto the sample 700.

[0064] The objective lens 708 focuses the electron beam, which has been deflected by the deflector 707, onto the sample 600. That is, the objective lens 708 functions as the second transmission lens 105 together with the second condenser lens 706. Since the electron beam is focused to the center point of the second lens 104B by the first lens 104A, the imaging position of the electron beam emitted from the objective lens 708 is maintained. In other words, readjustment of the lens intensity of the second condenser lens 706 and the objective lens 708 is unnecessary. In addition, the sample 700 emits signal electrons such as secondary electrons and backscattered electrons upon irradiation with the electron beam.

[0065] The detector 709 detects signal electrons emitted from the sample 700 and outputs the detection signal to the control unit 710.

[0066] The control unit 710 is, for example, a general-purpose computer, which controls each part and generates an observation image of the sample 700 based on the detection signal output from the detector 709.

[0067] In the electron microscope illustrated in Figure 6, the aperture 705 selects electron beams with large aberrations from the electron beam emitted from the electron gun 701, thereby canceling out off-axis aberrations that occur in the objective lens 708. In particular, the opening angle of the electron beam at the aperture 705 can be changed by acceleration and deceleration by the incident electrostatic lens 102, so the aberration of the electron beam selected by the aperture 705 can be adjusted. For example, if the electron beam is accelerated by the incident electrostatic lens 102, electron beams with a large opening angle, i.e., electron beams with large aberrations, will pass through the aperture 705, making it easier to cancel out off-axis aberrations that occur in the objective lens 708.

[0068] Furthermore, even when acceleration or deceleration occurs due to the incident electrostatic lens 102, the first lens 104A focuses the electron beam that has passed through the aperture 605 onto the center point of the second lens 104B, eliminating the need to readjust the second condenser lens 706 and the objective lens 708. As a result, a decrease in the throughput of the electron microscope can be suppressed.

[0069] The embodiments of the present invention have been described above. The present invention is not limited to the embodiments described above, and the components can be modified and implemented without departing from the spirit of the invention. Furthermore, the multiple components disclosed in the above embodiments may be combined as appropriate. In addition, some components may be deleted from all the components shown in the above embodiments.

[0070] Electron beam 100, first transmission lens 101, incident electrostatic lens 102, trajectory change unit 103, exit electrostatic lens 104, first lens 104A, second lens 104B, second transmission lens 105, energy analyzer 200, energy slit 201, sample 300, light source 301, objective lens 302, input lens 303, output lens 304, projection lens 305, detector 306, control unit 307, sample 500, objective lens 501, deflector 502, E×B deflector 503, focusing lens 50 4. Aperture 505, projection lens 506, detector 507, control unit 508, sample 600, electron gun 601, extraction electrode 602, accelerating electrode 603, first condenser lens 604, aperture 605, second condenser lens 606, deflector 607, objective lens 608, detector 609, control unit 610, sample 700, electron gun 701, extraction electrode 702, accelerating electrode 703, first condenser lens 704, aperture 705, second condenser lens 706, deflector 707, objective lens 708, detector 709, control unit 710.

Claims

1. An electron microscope comprising: a first transmission lens that transmits electrons under fixed conditions; an incident electrostatic lens that decelerates or accelerates electrons transmitted by the first transmission lens; an orbital change unit that changes the orbit of electrons decelerated or accelerated by the incident electrostatic lens; an exit electrostatic lens that accelerates or decelerates electrons whose orbits have been changed by the orbital change unit; and a second transmission lens that transmits electrons decelerated or accelerated by the exit electrostatic lens under fixed conditions, wherein the exit electrostatic lens has a first lens and a second lens, and the first lens focuses electrons whose orbits have been changed by the orbital change unit to the center point of the second lens.

2. An electron microscope according to claim 1, wherein the electrons incident on the first transfer lens are emitted from a sample irradiated with light, the orbital change section is an energy analyzer in which two hemispherical electrodes of different radii are arranged concentrically, and a higher voltage is applied to the inner hemispherical electrode than to the outer hemispherical electrode, and the electron microscope further comprises a detector that detects electrons emitted from the energy analyzer via the output-side electrostatic lens and the second transfer lens.

3. An electron microscope according to claim 1, wherein the orbital change portion is an aperture having a hole through which electrons pass.

4. An electron microscope according to claim 3, further comprising a detector that detects electrons that have passed through the aperture via the output electrostatic lens and the second transmission lens.

5. An electron microscope according to claim 3, characterized in that electrons that have passed through the aperture are irradiated onto a sample via the output electrostatic lens and the second transmission lens.

6. An electron microscope according to claim 5, further comprising an electron source for emitting an electron beam, wherein the aperture covers the central axis of the electron-optical microscope tube.

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