A charged particle optics for a charged particle beam apparatus, a charged particle beam apparatus, and a method for imaging a sample in a charged particle beam device

Abstract

A charged particle optical device for a charged particle beam apparatus is described, the charged particle beam apparatus having a charged particle beam and a beam propagation direction of the charged particle beam apparatus. The charged particle optical device includes a focusing lens. The focusing lens includes: a first electrode having a first aperture; a second electrode having a second aperture, the second electrode being mechanically movable at least in a first direction perpendicular to the beam propagation direction; and an actuator coupled to the second electrode to move the second electrode at least in the first direction, thereby displacing the second aperture relative to the first aperture. The charged particle optical device further includes: a deflection system positioned upstream of the second electrode for deflecting the charged particle beam based on the displacement, thereby guiding the charged particle beam through the second aperture.

Description

Charged Particle Optical Device, Charged Particle Beam Device for a Charged Particle Beam Apparatus, and Method for Imaging a Sample in a Charged Particle Beam Facility Embodiments described herein relate to a charged particle optical device for a charged particle beam apparatus, such as in an electron microscope, particularly in a scanning electron microscope (SEM). Embodiments further relate to a method for scanning a charged particle beam over a sample in a charged particle beam facility. Specifically, embodiments relate to a charged particle optical device for a charged particle beam apparatus, a charged particle beam apparatus, and a method for imaging a sample in a charged particle beam facility. Modern semiconductor technology places high demands on constructing and detecting samples at the nano- and even sub-nano scale. A charged particle beam (e.g., an electron beam), which is typically generated, shaped, deflected, and focused in a charged particle beam apparatus such as an electron microscope or an electron beam pattern generator, is used to accomplish micron- and nano-scale process control, inspection, or fabrication. For inspection purposes, a charged particle beam offers excellent spatial resolution compared to, for example, a photon beam. Devices using a charged particle beam, such as a scanning electron microscope (SEM), have many functions in a plurality of industrial fields, including but not limited to inspection of electronic circuits, exposure systems for lithography, detection systems, defect inspection tools, and test systems for integrated circuits. In such particle beam systems, a fine beam probe with a high current density can be used. For example, in the case of an SEM, a primary electron beam generates signal particles such as secondary electrons (SE) and / or backscattered electrons (BSE), which can be used to image and / or inspect a sample. However, it is challenging to reliably inspect and / or image a sample with good resolution using a charged particle beam device. In addition, particularly in the semiconductor industry, the throughput, for example, of image generation, is advantageously high. Further, a low-energy particle beam is beneficial for in-line inspection and / or imaging. Throughput influencing factors such as the field of view (FOV) size (especially a FOV size limited relative to the wafer size) and the collection efficiency of signal particles, as well as factors such as the resolution and beam energy on a sample (e.g., a wafer), can be conflicting for a beneficial design of electro-optical components. In view of the above, it is beneficial to provide an improved charged particle optical device for a charged particle beam apparatus, an improved charged particle beam apparatus, and an improved method for scanning a charged particle beam over a sample. In view of the above, a charged particle optical device for a charged particle beam apparatus, a charged particle beam apparatus, and a method for focusing a charged particle beam are provided according to the independent claims. According to an embodiment, there is provided a charged particle optical device for a charged particle beam apparatus, the charged particle beam apparatus having a charged particle beam and a beam propagation direction of the charged particle beam apparatus. The charged particle optical device includes a focusing lens. The focusing lens includes: a first electrode having a first aperture; a second electrode having a second aperture, the second electrode being mechanically movable at least in a first direction perpendicular to the beam propagation direction; and an actuator coupled to the second electrode to move the second electrode at least in the first direction, thereby performing a displacement of the second aperture relative to the first aperture. The charged particle optical device further includes: a deflection system positioned upstream of the second electrode for deflecting the charged particle beam based on the displacement, thereby guiding the charged particle beam through the second aperture. According to an embodiment, there is provided a charged particle beam apparatus. The charged particle beam apparatus includes: an emitter configured to emit a charged particle beam; a scanning deflector for scanning the charged particle beam within a field of view; and a charged particle optical device as in any of the embodiments described herein, wherein the charged particle optical device is configured to focus the charged particle beam and deflect the charged particle beam within a moving field. According to an embodiment, there is provided a method for imaging a sample in a charged particle beam device having a charged particle optical device having at least: a first electrode having a first aperture and a second electrode having a second aperture. The method includes: (a) moving a second electrode having a second aperture at least in a first direction perpendicular to the beam propagation direction, thereby performing a displacement of the second aperture relative to the first aperture; (b) guiding the charged particle beam through the first aperture of the first electrode; (c) deflecting the charged particle beam based on the displacement of the second aperture relative to the first aperture; (d) guiding the charged particle beam through the second aperture onto the sample; (e) focusing the charged particle beam using a focusing lens including the first electrode and the second electrode; and (f) scanning the charged particle beam above the sample. Further advantages, features, aspects, and details that can be combined with the embodiments described herein are apparent from the dependent claims, the description, and the drawings. Reference will now be made in detail to various embodiments, one or more examples of which are shown in the drawings. In the following description of the drawings, like reference numerals represent like components. In general, only the differences relative to each individual embodiment are described. Each example is provided by way of explanation and not intended to be limiting. Additionally, features shown or described as part of one embodiment can be used in other embodiments or combined with other embodiments to yield yet further embodiments. The description is intended to include such modifications and variations. According to an embodiment, a charged particle optical device for a charged particle beam apparatus is described, the charged particle beam apparatus having a charged particle beam and a beam propagation direction of the charged particle beam apparatus. The charged particle optical device includes a focusing lens having: a first electrode having a first aperture; a second electrode having a second aperture, the second electrode being mechanically movable at least in a first direction perpendicular to the beam propagation direction; and an actuator coupled to the second electrode to move the second electrode at least in the first direction, thereby effecting a displacement of the second aperture relative to the first aperture. The charged particle optical device further includes: a deflection system positioned upstream of the second electrode for deflecting the charged particle beam based on the displacement to direct the charged particle beam through the second aperture. The second electrode can be very light, which results in the second electrode being more easily movable than the substrate. In particular, the second electrode can move faster than the substrate. By moving the second electrode to a new position where an image can be acquired, the administrative burden time between images is reduced compared to moving a sample (such as a substrate). Moving the charged particle beam in association with moving the second electrode can increase the throughput of a device using a charged particle beam, such as a scanning electron microscope (SEM). The charged particle beam can be deflected by the deflection system based on the displacement of the second electrode to direct the charged particle beam through the second aperture. Throughout this case, based on the displacement of the second electrode, it should be understood that, unless otherwise indicated, the charged particle beam is deflected in such a manner that the deflection of the charged particle beam results in a displacement of the charged particle beam that is measured in the plane of the second electrode and is equal to the displacement of the second electrode. Compared to a lens without a movable electrode, the second electrode that is mechanically movable at least in a first direction perpendicular to the beam propagation direction results in an increased main field of view. The main field of view is a combination of the movement field of the second electrode and the field of view of the scanning system (i.e., the sub-field of view corresponding to the scan of the scanning deflector). Advantageously, the deflection system can deflect the charged particle beam based on the displacement to direct the charged particle beam through the center of the second aperture. The first aperture and the second aperture can be located at the position of the charged particle beam, even at an off-axis position that is larger compared to the FOV without moving the second electrode. By moving the second electrode to observe a desired position on a wafer, such as a designated surface area, off-axis aberration can be reduced. In some embodiments that can be combined with other embodiments described herein, the displacement can be at least in the range of tens of micrometers, such as 20 μm or greater. The displacement can be up to several millimeters, such as up to 10 mm. The displacement can be in the first direction and the second direction, respectively. Specifically, the second direction can be perpendicular to the beam propagation direction. The first direction and the second direction can form a plane, wherein the beam propagation direction is perpendicular to the plane. FIG. 1A is a schematic diagram of a charged particle beam apparatus 100 for inspecting and / or imaging a sample 10 according to an embodiment described herein. The charged particle beam apparatus 100 includes a charged particle source 105. The charged particle source may be configured to emit a charged particle beam 11. The charged particle beam may be an electron beam. The charged particle beam may propagate along an optical axis A. Throughout this case, unless otherwise indicated, the beam propagation direction 12 is understood to be the direction in which the charged particle beam travels from the charged particle source towards the charged particle optical device. The charged particle beam may be deflected in the charged particle optical device by a deflection system. After the charged particle beam is deflected by the deflection system, the charged particle beam may travel in a further direction. The direction of the charged particle beam after being deflected by the deflection system is understood to be the deflected beam propagation direction. The beam propagation direction may be, for example, along the z-axis of the charged particle beam apparatus, as shown in FIG. 1A. The beam propagation direction may be perpendicular to the opening of the first aperture. The optical axis A is understood to be the path of the charged particle beam from the source to the charged particle optical device or the path of the charged particle beam entering the focusing lens, such as the symmetry axis of the first electrode and / or the magnetic lens. The beam propagation direction may be parallel to and / or along the optical axis of the charged particle beam apparatus, particularly for a direct-view charged particle beam apparatus. The charged particle beam apparatus 100 further includes a sample stage 108. The sample 10 may be placed on the sample stage 108. The charged particle beam apparatus 100 further includes a charged particle optical device 200 for moving the charged particle beam above the sample and for focusing the charged particle beam according to an embodiment described herein. The charged particle optical device 200 includes, for example, a focusing lens and an actuator described with reference to FIGS. 2A and 2B. The focusing lens may be an objective lens or a part of an objective lens. The focusing lens may focus the charged particle beam 11 on the sample. The charged particle beam apparatus 100 further includes a charged particle detector 118, particularly an electron detector. The charged particle detector 118 may detect signal particles emitted from the sample 10. The charged particle detector 118 may detect signal electrons, such as secondary electrons and / or backscattered electrons. An image generation unit (not shown) may be provided. The image generation unit may be configured to generate one or more images of the sample 10. The image generation unit may generate one or more images based on signals received from the charged particle detector 118. The sample stage 108 can be a movable stage. Specifically, the sample stage 108 can move in the Z direction (i.e., in the direction of the optical axis 12) such that the distance between the focusing lens and the sample stage 108 can vary (see arrow 112 in FIG. 1A). By moving the sample stage 108 in the Z direction, the sample 10 can be moved to different "working distances". In addition, the sample stage 108 can also move in a plane perpendicular to the optical axis A (also referred to herein as the X-Y plane). By moving the sample stage 108 in the X-Y plane, a designated surface area of the sample 10 can be moved into the area below the charged particle optical device 200, such that the designated surface area can be imaged by focusing the charged particle beam 11 on the surface area of the sample. The beam optical components of the charged particle beam device 100 can be placed in a vacuum chamber 101 that can be evacuated. A vacuum can be beneficial for the propagation of the charged particle beam 11 (e.g., along the optical axis A from the charged particle beam source 105 towards the sample stage 108). The charged particle beam can impinge on the sample 10 at a pressure below sub-atmospheric pressure (e.g., a pressure below 10 -3 mbar or a pressure below 10 -5 mbar). For example, the charged particle beam device 100 can be an electron microscope, particularly a scanning electron microscope. The beam focusing lens system 106 can be arranged downstream of the charged particle source 105. The beam focusing lens system 106 can collimate the charged particle beam 11 propagating towards the charged particle optical device 200. One or more surface areas of the sample 10 can be inspected and / or imaged using the charged particle beam device 100. The term "sample" as used herein can refer to, for example, a substrate, a semiconductor wafer, a glass substrate, a flexible substrate (such as a web substrate), or another sample to be inspected on which one or more layers or features are formed. The sample can be inspected for one or more of the following: (1) imaging the surface of the sample, (2) measuring the dimensions of one or more features of the sample, e.g., in the lateral direction, i.e., in the X-Y plane, (3) performing critical dimension measurements and / or metrology, (4) detecting defects, and / or (5) investigating the quality of the sample. To inspect the sample 10 with the charged particle beam 11, the charged particle beam 11 can be focused on the sample surface using a focusing lens. The focusing of the focusing lens can be improved by correcting spherical aberration. When the charged particle beam 11 impinges on the sample surface, secondary electrons and / or backscattered electrons (referred to as "signal electrons") are emitted from the sample. The signal electrons provide information about the spatial characteristics and dimensions of the sample features. The signal electrons can be detected using the charged particle detector 118. The scanning deflector 107 can scan the charged particle beam 11 above the sample. Signal electrons that vary with time can be detected, and thus the generation position of the signal electrons can be determined. The surface of the sample or a part thereof can be imaged, for example, by an image generation unit, which can be configured to provide an image of the sample 10 based on the received signal electrons. A scanning deflector 107 can be provided for scanning the charged particle beam 11 above the surface of the sample 10 along a predetermined scanning pattern (e.g., in the X direction and / or the Y direction). The scanning deflector 107 can scan the charged particle beam 11 above the sample. The scanning range of the scanning deflector 107 can be limited in the X direction and / or the Y direction, for example, by an inclination angle or a first aperture and / or a second aperture. The scanning deflector 107 has a field of view (FOV) corresponding to the scanning range. The FOV is an area or a projected area on the sample surface that can be scanned by the scanning deflector. Specifically, the FOV is a projected area on the sample surface that defines the area where the scanning deflector can scan for the set position of the second electrode and the set position of the sample. The charged particle optical device 200 can deflect or move the charged particle beam, for example, in the X direction and / or the Y direction. The deflection of the charged particle optical device 200 can be superimposed on the deflection of the scanning deflector 107, such that the position of the FOV on the surface of the sample 10 can be changed. The deflection range of the charged particle optical device 200 can be provided in the X direction and / or the Y direction, for example, by a deflection system and / or the displacement of the second electrode. The charged particle optical device 200 has a movement field (FOM) corresponding to the movement range of the second electrode and / or the deflection range of the deflection system of the charged particle optical device. The charged particle optical device 200 can deflect the charged particle beam to a position within the FOM. Specifically, the charged particle optical device 200 can deflect the FOV to a position within the FOM. The superposition of the FOV of the scanning deflector 107 and the FOM of the charged particle optical device 200 generates the main FOV of the charged particle beam device. The FOV of the scanning deflector can provide a sub-FOV within the main field of view. The main FOV is larger than the sub-FOV of the scanning deflector. The main FOV provides faster imaging of a specified surface area to be imaged. Multiple surface areas (FOVs) can be scanned independently of each other to find a set sample position, i.e., without moving the sample. Throughout this case, unless otherwise indicated, two surface areas are independent of each other if they do not overlap and / or cannot be scanned in a single FOV. For example, to image a specified surface area, the sample stage 108 can be moved to place the specified surface area within the main field of view of the charged particle optical device 200. The charged particle optical device 200 can move the FOV of the scanning deflector 107 such that the surface area to be scanned is within the FOV. The FOM can be adjusted faster and more precisely than the sample stage 108, which allows for faster adjustment. After scanning the surface area, the charged particle optical device 200 can move and / or deflect the FOV to a further surface area within the main field of view such that the FOV at the further surface area is independent of the surface area, e.g., does not overlap with the FOV at the previous surface area. Figure 1B illustrates a top view of the surface of the sample 10, having the FOV 40 of the scanning deflector 107 and the FOM 30 of the charged particle optical device 200. Without the charged particle optical device 200 deflecting the FOV 40, the FOV is centered on the center 20 of the FOM. The charged particle optical device 200 can move and / or deflect the FOV within the FOM, as shown by the dashed FOV. In particular, the charged particle optical device 200 can move and / or deflect the center of the FOV within the FOM. The FOM and the FOV produce the main field of view 35 as shown in Figure 1B. The first electrode and the second electrode can be configured such that a voltage can be applied to the first electrode and the second electrode. In some embodiments, which can be combined with other embodiments described herein, the charged particle optical device can include a voltage supply element connected to the first electrode and the second electrode and configured to provide a voltage difference between the first electrode and the second electrode. For example, the voltage supply element can include a voltage supply connected to the first electrode and the second electrode. For example, the voltage supply element can include a first voltage supply connected to the first electrode and ground and a second voltage supply connected to the second electrode and ground, wherein the second voltage of the second voltage supply is independent of the first voltage. The first voltage supply and the second voltage supply can be configured to supply a first voltage to the first electrode and a second voltage to the second electrode to decelerate the charged particles of the charged particle beam by the second electrode. Specifically, for negatively charged charged particles, a first voltage is supplied to the first electrode, which is higher than the second voltage supplied to the second electrode, and for positively charged charged particles, a first voltage is supplied to the first electrode, which is lower than the second voltage supplied to the second electrode. FIG. 2A is a schematic diagram of a charged particle optical device 200 according to an embodiment described herein. The charged particle optical device 200 includes a focusing lens 210, which has an electrostatic focusing lens and an optional magnetic focusing lens for focusing a charged particle beam on the surface of a sample 10. The focusing lens may be an objective lens, particularly an electrostatic magnetic objective lens. In some embodiments that may be combined with other embodiments described herein, the focusing lens includes a magnetic lens for focusing the charged particle beam. The focusing lens 210 (particularly the electrostatic lens of the focusing lens 210) includes a first electrode 220 having a first aperture 225 and a second electrode 230 having a second aperture 235. The charged particle beam 11 may be guided through the first aperture 225 and through the second aperture. In some embodiments that may be combined with other embodiments described herein, the first aperture and the second aperture are spaced apart by at least 1 mm along the beam propagation direction, and particularly up to 20 mm. The second electrode may be mechanically movable at least in a first direction perpendicular to the beam propagation direction. An actuator 250 is coupled to the second electrode to move the second electrode at least in the first direction. The first direction is perpendicular to the beam propagation direction. The first direction may be, for example, along the x direction shown in FIG. 2A. The second electrode may be mechanically movable in a second direction perpendicular to the beam direction. The second direction may be, for example, along the y direction shown in FIG. 2A. A further actuator may be coupled to the second electrode to move the second electrode in the second direction. The first direction and the second direction may define a plane. The beam propagation direction may be perpendicular to the plane. The movement range (i.e., the displacement of the second electrode) may be in the range of several tens of micrometers, such as 20 μm or more. For each direction (x direction and y direction), the movement range may be up to several millimeters, such as up to 5 mm or 10 mm. According to some embodiments of the present case, the actuator 250 may move the second electrode from a first position within the FOM to a second position within the FOM. Specifically, the second electrode may be moved after generating an image or a sub-image of the FOV at the first position. Each time an image or a sub-image of the FOV is generated, the FOV may be moved to a new position within the FOM. As described above, by moving the second electrode to a new position where an image can be acquired, the management burden time between images is reduced compared to moving the sample. Therefore, the actuator 250 and / or the second electrode may be configured to move within 1 second or less, particularly within 100 milliseconds or less, or even within 20 milliseconds or less. The charged particle optical device includes a deflection system 240. The deflection system 240 is upstream of the second electrode 230. According to some embodiments of the present case, the deflection system may include one or more deflectors, particularly one or more deflectors for each of the x and y directions. For example, the first deflector of the deflection system may be an alignment deflector to align the charged particle beam to the second electrode, that is, to deflect the charged particle beam to the aperture of the second electrode after, for example, the movement of the second electrode. According to a further embodiment, the deflection system may include an alignment deflector and an anti-alignment deflector (for each direction). As示例性 shown in FIG. 2B, a further deflector may be provided. The deflection system 240 or at least one deflector of the deflection system may be placed upstream of the first electrode. According to some embodiments, a magnetic deflector may also be placed between the first electrode and the second electrode. In some embodiments that may be combined with other embodiments described herein, the deflection system includes a magnetic deflector. In an alternative embodiment, the deflection system includes an electrostatic deflector, particularly an electrostatic deflector placed upstream of the first electrode. The deflection system 240 may deflect the charged particle beam by an angle α such that the charged particle beam propagates along a deflected beam propagation direction 212 that is at an angle α to the beam propagation direction 12. The deflected charged particle beam impinges on the sample at an inclination angle measured relative to the surface normal. The inclination angle may be the angle α. By adjusting the position of the FOV of the scanning deflector 107 within the FOM of the charged particle optical device 200, the inclination angle α can be adjusted. According to some embodiments that may be combined with other embodiments described herein, the inclination angle is up to α max 30°. For example, as示例性 shown by the beam path in FIG. 2B, a magnetic deflector (i.e., an inclination deflector) may be placed adjacent to the second electrode, for example, above the second electrode. The inclination deflector may cause beam inclination. An actuator may move the second electrode to adjust the position of the second electrode based on the beam inclination. Thus, for embodiments including beam inclination, the second electrode may be moved within the FOM such that the inclined beam passes through the second aperture at a predetermined position (e.g., the center of the aperture) within the second aperture. Aberrations may be reduced by guiding the inclined beam through the center of the second aperture, for example, by adjusting the position of the second aperture to the beam inclination. A charged particle optical device may include a deflection system having an alignment deflector and an anti-alignment deflector, as shown by the dashed lines in FIG. 2A. The anti-alignment deflector may be upstream of the second electrode and the first electrode. The anti-alignment deflector may reverse the deflection of the charged particle beam caused by the alignment deflector. The anti-alignment deflector may deflect the deflected charged particle beam by an angle α´ such that the charged particle beam propagates along a third beam propagation direction that is at an angle α´ to the propagation direction of the deflected beam. In particular, α´ = -α may be satisfied, and the third beam propagation direction corresponds to the beam propagation direction. According to some embodiments that may be combined with other embodiments described herein, the combination of the alignment deflector and the anti-alignment deflector may produce a beam landing angle without beam tilt, i.e., 0°. As shown by the dashed beam path in FIG. 2A, the charged particle beam may pass through the first aperture at an off-axis position (e.g., the center of the first aperture) relative to the axis of the first aperture or the first aperture. Since the first electrode provides a weak focusing field, as shown by the equipotential lines, passing through the first aperture off-axis may introduce relatively small aberrations. For example, when the beam has a 0° tilt angle, the beam may pass through the second aperture on-axis. Since the second electrode has a stronger focusing field than the first electrode, it is advantageous to pass through the center of the second aperture. In some embodiments that may be combined with other embodiments described herein, a charged particle optical device may include a deflection system having an anti-alignment deflector configured to deflect a charged particle beam contrary to the deflection of the charged particle beam by an alignment deflector of the deflection system, thereby resulting in a parallel displacement of the charged particle beam. In particular, the second deflection may be based on the first deflection to produce a z displacement, resulting in a parallel displacement of the charged particle beam. According to some embodiments that may be combined with other embodiments described herein, the deflection system may include an alignment deflector and an anti-alignment deflector, wherein the alignment deflector and the anti-alignment deflector apply deflection angles in opposite directions. As shown in FIG. 2B, the deflection system 240 may include a further deflector. For example, a deflector provided upstream of a focusing lens (particularly a magnetic lens) may deflect the charged particle beam away from the optical axis. A second deflector (e.g., an alignment deflector) may deflect the charged particle beam to pass through the first aperture and the second aperture on-axis, e.g., through the center of the first aperture and the center of the second aperture. Figure 3 illustrates a flowchart of a method 300 for imaging a sample with a charged particle beam in a charged particle beam device according to an embodiment described herein. At operation 310, a second electrode having a second aperture is moved at least in a first direction perpendicular to the beam propagation direction, thereby effecting a displacement of the second aperture relative to the first aperture. The charged particle beam propagates from a source towards the first aperture in the beam propagation direction. The beam propagation direction may be, for example, along the z-axis as shown in FIG. 1A. The second electrode may be moved, for example, along the X direction and / or the Y direction. At operation 320, the charged particle beam is guided through the first aperture of the first electrode. Additionally, at operation 330, the charged particle beam is deflected based on the displacement of the second aperture relative to the first aperture. The charged particle beam may be deflected by an angle α such that the charged particle beam propagates along a deflected beam propagation direction. The deflection angle α is such that the displacement of the charged particle beam in the plane of the second electrode corresponds to the displacement of the second electrode relative to the first aperture. According to operation 340, the charged particle beam is guided through the second aperture onto the sample. Guiding the charged particle beam through the second electrode having a displacement relative to the first electrode results in a displacement of the FOV of the scanning deflector. The FOV of the scanning deflector may be shifted into the FOM. According to operation 350, the charged particle beam is focused using a focusing lens including the first electrode and the second electrode. At operation 360, the charged particle beam is scanned above the sample by a scanning deflector. The scanning deflector scans the charged particle beam above the sample within the FOV. According to an embodiment, a method 300 for imaging a sample in a charged particle beam device is described. The method includes the following operations: (a) moving a second electrode having a second aperture at least in a first direction perpendicular to the beam propagation direction, thereby effecting a displacement of the second aperture relative to the first aperture; (b) guiding a charged particle beam through the first aperture of the first electrode; (c) deflecting the charged particle beam based on the displacement of the second aperture relative to the first aperture; (d) guiding the charged particle beam through the second aperture onto the sample; (e) focusing the charged particle beam using a focusing lens including the first electrode and the second electrode; and (f) scanning the charged particle beam above the sample. According to some embodiments that may be combined with other embodiments described herein, the charged particle beam may be guided off-axis through the first aperture relative to a first axis of the first aperture and may be guided on-axis through the second aperture relative to a second axis of the second aperture. For example, the charged particle beam may be guided off-axis through the first aperture and may be guided through the second aperture to be parallel to the beam propagation direction before entering the charged particle optical device. The deflection system may deflect the charged particle beam by reversing the deflection of the charged particle beam to provide a parallel displacement of the charged particle beam. According to some embodiments that can be combined with other embodiments described herein, as示例性 shown by the beam path of FIG. 2B, a charged particle beam can be axially guided through a first aperture relative to a first axis of the first aperture, and can be axially guided through a second aperture relative to a second axis of the second aperture. Embodiments of the present case allow for generating images at various FOVs without moving the sample. Thus, the operations of (a) moving the second electrode, (b) guiding the charged particle beam through the first aperture, (c) deflecting the charged particle beam, (d) guiding the charged particle beam through the second aperture, (e) focusing the charged particle beam, and (f) scanning the charged particle beam above the sample can be repeated one or more times. Specifically, between repeating the operations, the second electrode can be moved from a first position within the movement field to a second position within the movement field. Alternatively, the second electrode can be continuously moved, and the beam can be guided through the second aperture by continuously deflecting the charged particle beam in a manner corresponding to the continuous movement of the second electrode. For example, moving the second aperture can be a continuous movement, and deflecting the charged particle beam can be a corresponding continuous deflection. In some embodiments that can be combined with other embodiments described herein, focusing the charged particle beam can further include providing a voltage difference between a first electrode and a second voltage to the second electrode, particularly for decelerating the charged particle beam. In some embodiments that can be combined with other embodiments described herein, method 300 further includes deflecting the charged particle beam contrary to the deflection of the charged particle beam to provide a parallel displacement of the charged particle beam. The charged particle beam is deflected by a reverse alignment deflector by an angle α´ = -α such that the charged particle beam propagates along the beam propagation direction. The charged particle beam has a parallel displacement relative to the optical axis. According to some embodiments that can be combined with other embodiments described herein, the deflection of the charged particle beam through the first aperture and / or the second aperture can be adapted to optimize the spot size on the sample, and / or provide a minimum chromatic aberration and / or coma. In view of the stronger focusing field of the second electrode, the deflection through the second aperture can be particularly optimized as described above. In some embodiments that can be combined with other embodiments described herein, method 300 further includes focusing the charged particle beam with a magnetic lens. The magnetic lens can focus the charged particle beam on the sample surface to reduce the spot size of the charged particle beam. In view of the above, the present invention provides a plurality of embodiments, some of which are as follows: Embodiment 1. A charged particle optical device for a charged particle beam device, the charged particle beam device having a charged particle beam and a beam propagation direction of the charged particle beam device, the charged particle optical device comprising: a focusing lens, the focusing lens comprising: a first electrode having a first aperture; a second electrode having a second aperture, the second electrode being mechanically movable at least in a first direction perpendicular to the beam propagation direction; and an actuator coupled to the second electrode to move the second electrode at least in the first direction, thereby effecting a displacement of the second aperture relative to the first aperture; the charged particle optical device further comprising: a deflection system positioned upstream of the second electrode for deflecting the charged particle beam based on the displacement, thereby guiding the charged particle beam through the second aperture. Embodiment 2. The charged particle optical device according to Embodiment 1, wherein the displacement can be at least 20 μm in the first direction and the second direction, respectively. Embodiment 3. The charged particle optical device according to any one of Embodiments 1 to 2, further comprising: a voltage supply element connected to the first electrode and the second electrode and configured to provide a voltage difference between the first electrode and the second electrode. Embodiment 4. The charged particle optical device according to Embodiment 3, wherein the voltage supply element comprises a first voltage supply and a second voltage supply, the first voltage supply and the second voltage supply being configured to provide a first voltage relative to ground to the first electrode and a second voltage relative to ground to the second electrode to decelerate the charged particles of the charged particle beam by the second electrode. Embodiment 5. The charged particle optical device according to any one of Embodiments 1 to 4, wherein the first aperture and the second aperture are spaced apart by at least 1 mm along the beam propagation direction. Embodiment 6. The charged particle optical device according to any one of Embodiments 1 to 5, wherein the deflection system comprises an electrostatic deflector placed upstream of the second electrode. Embodiment 7. The charged particle optical device according to any one of Embodiments 1 to 6, wherein the deflection system comprises a magnetic deflector placed upstream of the second electrode. Embodiment 8. The charged particle optical device according to any one of Embodiments 1 to 7, wherein the focusing lens comprises a magnetic lens for focusing the charged particle beam, in particular, wherein the magnetic lens is placed upstream of the second aperture. Embodiment 9. The charged particle optical device according to any one of Embodiments 1 to 8, wherein the deflection system comprises: an alignment deflector; and a reverse alignment deflector, wherein the alignment deflector and the reverse alignment deflector apply deflection angles in opposite directions. Example 10. A charged particle beam device includes: an emitter configured to emit a charged particle beam; a scanning deflector for scanning the charged particle beam within a field of view; and a charged particle optical device as described in any one of Examples 1 to 9, wherein the charged particle optical device is configured to focus the charged particle beam and deflect the charged particle beam within a moving field. Example 11. A method for imaging a sample in a charged particle beam device having a charged particle optical device having at least: a first electrode having a first aperture and a second electrode having a second aperture, the method comprising: (a) moving the second electrode having the second aperture at least in a first direction perpendicular to the beam propagation direction, thereby effecting a displacement of the second aperture relative to the first aperture; (b) guiding the charged particle beam through the first aperture of the first electrode; (c) deflecting the charged particle beam based on the displacement of the second aperture relative to the first aperture; (d) guiding the charged particle beam through the second aperture onto the sample; (e) focusing the charged particle beam using a focusing lens including the first electrode and the second electrode; and (f) scanning the charged particle beam above the sample. Example 12. The method according to Example 11, wherein the charged particle beam is guided off-axis with respect to a first axis of the first aperture and is guided axially with respect to a second axis of the second aperture. Example 13. The method according to any one of Examples 11 to 12, wherein the charged particle beam is guided off-axis with respect to a first axis of the first aperture and is guided through the second aperture parallel to the beam propagation direction before entering the charged particle optical device. Example 14. The method according to any one of Examples 11 to 13, further comprising: deflecting the charged particle beam by reversing the deflection of the charged particle beam to provide a parallel displacement of the charged particle beam. Example 15. The method according to Example 11, wherein the charged particle beam is guided axially with respect to a first axis of the first aperture and is guided axially with respect to a second axis of the second aperture. Example 16. The method according to any one of Examples 11 to 15, further comprising: decelerating the charged particle beam by the second electrode. Example 17. The method according to any one of Examples 11 to 16, further comprising: additionally focusing the charged particle beam with a magnetic lens. Example 18. The method according to any one of Examples 11 to 17, further comprising: repeating operations (a) to (f), wherein the second electrode moves from a first position within the moving field to a second position within the moving field during operation (a). Example 19. The method according to any one of Examples 11 to 17, wherein moving the second aperture is a continuous movement, and deflecting the charged particle beam is a corresponding continuous deflection. Although the foregoing is directed to examples, other and further examples may be conceived without departing from the basic scope, and the scope thereof is determined by the appended patent claims. 10: Sample 11: Charged particle beam 12: Beam propagation direction 20: Center 30: FOM 35: Main field of view 40: FOV 100: Charged particle beam device 101: Vacuum chamber 105: Charged particle source 106: Beam focusing lens system 107: Scanning deflector 108: Sample stage 112: Arrow 118: Charged particle detector 200: Charged particle optical device 210: Focusing lens 212: Deflected beam propagation direction 220: First electrode 225: First aperture 230: Second electrode 235: Second aperture 240: Deflection system 250: Actuator 300: Method 310: Operation 320: Operation 330: Operation 340: Operation 350: Operation 360: Operation To be able to understand the above features of the present case in detail, a more specific description of what was briefly summarized above can be obtained by referring to the examples. The accompanying drawings relate to one or more examples and are described below. FIG. 1A illustrates a schematic diagram of a charged particle system according to an example described herein. FIG. 1B illustrates a top view of a sample surface having a field of view (FOV) and a field of motion (FOM) with a scanning deflector. FIG. 2A illustrates a schematic diagram of a charged particle optical device according to an example described herein. FIG. 2B illustrates a schematic diagram of a charged particle optical device according to an example described herein. FIG. 3 illustrates a flowchart of a method of scanning a charged particle beam on a substrate in a charged particle beam device according to an example described herein. Domestic deposit information (please note in the order of deposit institution, date, number) None Foreign deposit information (please note in the order of deposit country, institution, date, number) None 10: Sample 11: Charged particle beam 200: Charged particle optical device 210: Focusing lens 212: Deflected beam propagation direction 220: First electrode 225: First aperture 230: Second electrode 235: Second aperture 240: Deflection system 250: Actuator

Claims

1. A charged particle optical device for a charged particle beam apparatus, the charged particle beam apparatus having a charged particle beam and a beam propagation direction of the charged particle beam apparatus, the charged particle optical device comprising: A focusing lens includes: a first electrode having a first aperture; a second electrode having a second aperture, the second electrode being mechanically movable at least in a first direction perpendicular to the beam propagation direction; and an actuator coupled to the second electrode to move the second electrode at least in the first direction, thereby displacing the second aperture relative to the first aperture; the charged particle optical device further includes: a deflection system positioned upstream of the second electrode for deflecting the charged particle beam based on the displacement, thereby guiding the charged particle beam through the second aperture.

2. The charged particle optical device of claim 1, wherein the displacement may be at least 20 μm mm in the first direction and in the second direction, respectively.

3. The charged particle optical device as described in any one of claims 1 and 2, further comprising: A voltage supply element is connected to the first electrode and the second electrode and is configured to provide a voltage difference between the first electrode and the second electrode.

4. The charged particle optical device of claim 3, wherein the voltage supply element includes a first voltage supply and a second voltage supply, the first voltage supply and the second voltage supply being configured to provide a first voltage relative to ground to the first electrode and a second voltage relative to ground to the second electrode, so as to decelerate the charged particles of the charged particle beam by means of the second electrode.

5. The charged particle optical device as claimed in any one of claims 1 and 2, wherein the first aperture and the second aperture are spaced apart by at least 1 mm along the beam propagation direction.

6. The charged particle optical device as claimed in any one of claims 1 and 2, wherein the deflection system includes an electrostatic deflector positioned upstream of the second electrode.

7. The charged particle optical device as claimed in any one of claims 1 and 2, wherein the deflection system includes a magnetic deflector placed upstream of the second electrode.

8. The charged particle optical device as claimed in any one of claims 1 and 2, wherein the focusing lens includes a magnetic lens for focusing the charged particle beam.

9. The charged particle optical device of claim 8, wherein the magnetic lens is positioned upstream of the second aperture.

10. The charged particle optical device as claimed in any one of claims 1 and 2, wherein the deflection system comprises: Align the deflector; and a reverse alignment deflector, wherein the alignment deflector and the reverse alignment deflector apply deflection angles in opposite directions.

11. A charged particle beam device, comprising: A transmitter configured to emit a charged particle beam; a scanning deflector for scanning the charged particle beam within a field of view; and a charged particle optical device as claimed in claim 1, wherein the charged particle optical device is configured to focus the charged particle beam and deflect the charged particle beam within a moving field.

12. A method for imaging a sample in a charged particle beam apparatus, the charged particle beam apparatus having a charged particle optics device having at least: a first electrode having a first aperture and a second electrode having a second aperture, the method comprising the steps of: (a) moving the second electrode having the second aperture in at least a first direction perpendicular to a beam propagation direction, thereby displacing the second aperture relative to the first aperture; (b) guiding a charged particle beam through the first aperture of the first electrode; (c) deflecting the charged particle beam based on the displacement of the second aperture relative to the first aperture; (d) guiding the charged particle beam through the second aperture onto the sample; (e) focusing the charged particle beam using a focusing lens including the first electrode and the second electrode; and (f) scanning the charged particle beam over the sample.

13. The method of claim 12, wherein the charged particle beam is off-axis guided through the first aperture by a first axis relative to the first aperture, and on-axis guided through the second aperture by a second axis relative to the second aperture.

14. The method of any one of claims 12 and 13, wherein the charged particle beam is guided off-axis through the first aperture relative to a first axis of the first aperture, and is guided through the second aperture to be parallel to the beam propagation direction prior to entering the charged particle optical device.

15. The method of any one of claims 12 and 13, further comprising the step of: deflecting the charged particle beam by reversing the deflection of the charged particle beam to provide a parallel displacement of the charged particle beam.

16. The method of claim 12, wherein the charged particle beam is axially guided through the first aperture by a first axis relative to the first aperture, and axially guided through the second aperture by a second axis relative to the second aperture.

17. The method of any one of claims 12, 13 and 16, further comprising the step of: slowing down the charged particle beam by means of the second electrode.

18. The method of any one of claims 12, 13 and 16, further comprising the step of: additionally focusing the charged particle beam with a magnetic lens.

19. The method of any one of claims 12, 13 and 16, further comprising the step of: repeating operations (a) to (f), wherein the second electrode moves from a first position in a moving field to a second position in the moving field during operation (a).

20. The method of any one of claims 12, 13 and 16, wherein moving the second aperture is a continuous movement and deflecting the charged particle beam is a corresponding continuous deflection.

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