Shielding mechanism for electro-optical modules

Abstract

A charged particle optical module for a charged particle optical device configured to guide a charged particle beam toward a sample position along a beam path, comprising: a stack including a charged particle optical plate positioned across the beam path and configured to act on the charged particle beam; and a shielding mechanism including an upstream electrostatic shield positioned across the beam path upstream of the charged particle optical plate and a downstream electrostatic shield positioned across the beam path downstream of the charged particle optical plate, wherein the shielding mechanism is configured to prevent electrical dielectric breakdown between the charged particle optical module and external components of the charged particle optical module, and / or to confine, for example, the electrostatic field generated when the charged particle optical plate acts on the charged particle beam along the beam path within the charged particle optical module.

Description

Technical Field

[0001] Cross - reference to related applications

[0001] This application claims priority to European Patent Application No. 23165343.7, filed on March 30, 2023, which is hereby incorporated by reference in its entirety.

[0002]

[0002] Embodiments provided herein generally relate to charged - particle optical modules, charged - particle optical devices, charged - particle optical apparatuses, and methods of guiding charged - particle beams.

Background Art

[0003]

[0003] When manufacturing semiconductor integrated circuit (IC) chips, unwanted pattern defects can occur on a substrate (e.g., a wafer) or a mask during the manufacturing process, thereby reducing the yield. Defects can occur, for example, as a result of optical effects and incident particles, or other processing steps such as etching, deposition of chemical - mechanical polishing. Therefore, monitoring the degree of unwanted pattern defects is an important process in the manufacture of IC chips. More generally, inspection and / or measurement of the surface of a substrate, or other object / material, is an important process during and / or after its manufacture.

[0004]

[0004] Pattern evaluation systems using charged particle beams, such as pattern inspection tools, have been used to evaluate objects, for example, to detect pattern defects. These tools typically use electron microscopy methods such as scanning electron microscopes (SEM). In an SEM, a primary electron beam of relatively high-energy electrons is directed towards the target in the final deceleration stage so that it is incident on the target at a relatively low incident energy. The electron beam is focused on the target as a probe spot. Interaction between the material structure at the probe spot and the incident electrons from the electron beam causes electrons such as secondary electrons, backscattered electrons, or Auger electrons, which can be collectively called signal electrons or more generally signal particles, to be emitted from the surface. The generated secondary electrons may be emitted from the material structure of the target.

[0005]

[0005] By scanning the target surface as a probe spot with a primary electron beam, secondary electrons can be emitted across the entire surface of the target. By collecting these emitted secondary electrons from the target surface, the pattern inspection tool (or apparatus) can obtain an image-like signal that represents the material structure characteristics of the target surface. In such inspection, the collected secondary electrons are detected by a detector in the apparatus. The detector generates a signal in response to the incident particles. Since an area of ​​the sample is being inspected, the signal contains data that is processed to generate an inspection image corresponding to the inspection area of ​​the sample. The image may contain pixels. Each pixel may correspond to a portion of the inspection area. Typically, an electron beam inspection apparatus has a single beam and may be called a single-beam SEM. Attempts have been made to introduce multi-electron beam inspection in apparatus (or "multi-beam tool") which may be called a multi-beam SEM (MBSEM (Multi Beam SEM)).

[0006]

[0006] Another application for electro-optical devices (or columns) is lithography. A charged particle beam reacts with a resist layer on the surface of a substrate. By controlling the location on the resist layer to which the charged particle beam is directed, a desired pattern can be created within the resist.

[0007]

[0007] An electro-optical device may be a device for generating, illuminating, projecting, and / or detecting one or more beams of charged particles. The path of the beams of charged particles is controlled by an electromagnetic field (i.e., an electrostatic field and optionally a magnetic field).

[0008]

[0008] For example, electrical signals (e.g., power and / or communications) may be transmitted to and from the electronic components of an electro-optical device in order to act on a beam of charged particles and / or process the signals of collected electrons. There is a risk of undesirable discharge between the electrical cables, electrical connectors, or electro-optical components of an electro-optical device and other components. [Overview of the project]

[0009]

[0009] The present invention provides an architecture suitable for reducing the risk of discharge.

[0010]

[0010] According to a first aspect of the present invention, a charged particle optical module for a charged particle optical device configured to guide a charged particle beam along a beam path toward a sample position, wherein the charged particle optical module is A stack comprising one or more charged particle optical plates positioned across the beam path and configured to act on a charged particle beam, A shielding mechanism comprising an upstream electrostatic shield positioned across the beam path upstream of one or more charged particle optical plates, and a downstream electrostatic shield positioned across the beam path downstream of one or more charged particle optical plates, Equipped with, A charged particle optical module is provided, wherein the shielding mechanism is configured to prevent electrical breakdown between the charged particle optical module and external components of the charged particle optical module, and / or to confine an electrostatic field within the charged particle optical module, the electrostatic field being generated, for example, when one or more charged particle optical plates act on a charged particle beam along the beam path.

[0011]

[0011] According to a second aspect of the present invention, a charged particle optical module for a charged particle optical device configured to guide a charged particle beam along a beam path toward a sample position, wherein the charged particle optical module is A stack comprising one or more charged particle optical plates positioned across the beam path and configured to act on a charged particle beam, At least one electrical connector configured to connect at least one of the charged particle optical plates to a voltage source, A shielding mechanism configured to extend across the beam path upstream and downstream of the stack's beam, and to protrude beyond the connector, A charged particle optics module is provided, which includes the following features.

[0012]

[0012] According to a third aspect of the present invention, a charged particle optical device configured to guide a charged particle beam along a beam path toward a sample position, wherein the charged particle optical device is A conductive tube configured to surround the beam path, Charged particle optics module, Equipped with a charged particle optics module, A stack comprising one or more charged particle optical plates positioned across the beam path and configured to act on a charged particle beam, A shielding mechanism configured to shield a stack and to extend upstream of the stack's beam in a direction across the beampath and downstream of the stack's beam in a direction across the beampath, wherein the shielding mechanism extends further from the beampath than the conductive tube and the stack, A charged particle optical device is provided that includes the following features.

[0013]

[0013] According to a fourth aspect of the present invention, a method for guiding a charged particle beam along a beam path toward a sample position, wherein the method is The act of acting on a charged particle beam with one or more charged particle optical plates in a stack, wherein the one or more charged particle optical plates are positioned across the beam path. A shielding mechanism is used to prevent electrical breakdown between the stack and external components of the stack, and / or, for example, to confine the electrostatic field generated when one or more charged particle optical plates act on the charged particle beam along the beam path within the shielding mechanism, including an upstream electrostatic shield positioned upstream of one or more charged particle optical plates across the beam path, and a downstream electrostatic shield positioned downstream of one or more charged particle optical plates across the beam path. A method is provided that includes this.

[0014]

[0014] The advantages of the present invention will become clear when you read the following description in conjunction with the accompanying drawings, which illustrate and illustrate specific embodiments of the present invention.

[0015]

[0015] The above and other aspects of the present disclosure will become more apparent from reading the description of the exemplary embodiments in conjunction with the accompanying drawings. [Brief explanation of the drawing]

[0016] [Figure 1]

[0016] This is a schematic diagram showing an exemplary electron beam evaluation apparatus. [Figure 2]

[0017] It is a schematic diagram showing an exemplary multi-beam electron optical device that is part of the exemplary electron beam evaluation apparatus of FIG. 1. [Figure 3]

[0018] It is a schematic diagram of an exemplary electron optical device including a collimator element array and a scan deflector array that are part of the exemplary electron beam evaluation apparatus of FIG. 1. [Figure 4]

[0019] It is a schematic diagram of an exemplary electron optical device array including the electron optical device of FIG. 3. [Figure 5]

[0020] It is a schematic diagram of an alternative exemplary electron optical device that is part of the exemplary electron beam evaluation apparatus of FIG. 1. [Figure 6]

[0021] It is a schematic diagram of an alternative exemplary electron optical device that is part of the exemplary electron beam evaluation apparatus of FIG. 1. [Figure 7]

[0022] It is a schematic diagram of an alternative exemplary electron optical device that is part of the exemplary electron beam evaluation apparatus of FIG. 1. [Figure 8]

[0023] It is a schematic diagram of an exemplary electron optical module that may be part of the electron optical devices of FIGS. 2 to 7. [Figure 9]

[0024] It is a schematic diagram of an exemplary electron optical module that may be part of the electron optical devices of FIGS. 2 to 7. [Figure 10]

[0025] It is a schematic diagram of an alternative exemplary electron optical module that may be part of the electron optical devices of FIGS. 2 to 7. [Figure 11]

[0026] It is a schematic diagram of a modified version of the electron optical module shown in FIG. 10. [Figure 12]

[0027] It is a schematic diagram of a modified version of the electron optical module shown in FIG. 10. [Figure 13]

[0028] It is an alternative view of the electron optical module shown in FIG. 10. [Figure 14]

[0029] Figures 2 to 7 are schematic cross-sectional views of a portion of an exemplary electro-optical module, which may be part of an electro-optical device. [Figure 15]

[0030] Figure 13 is a schematic diagram of a modified version of the electro-optical module. [Figure 16]

[0031] Figure 15 is a schematic diagram of a modified version of the electro-optical module. [Modes for carrying out the invention]

[0017]

[0032] Next, we will refer in detail to exemplary embodiments illustrated in the accompanying drawings. The following description refers to the accompanying drawings, where, unless otherwise noted, the same numbers in different drawings represent the same or similar elements. The implementations described below in the description of exemplary embodiments do not represent all implementations consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with the aspects relating to the present invention enumerated in the accompanying claims.

[0018]

[0033] Reducing the physical size of devices and improving the computing power of electronic devices can be achieved by significantly increasing the mounting density of circuit components such as transistors, capacitors, and diodes on an IC chip. This is made possible by higher resolution, which allows for the fabrication of even smaller structures. The manufacturing of semiconductor ICs is a complex and time-consuming process involving hundreds of individual steps. Any error in the process of manufacturing an IC chip can negatively affect the functionality of the final product. Just one defect could cause a device to fail. Improving the overall yield of the process is desirable. For example, to achieve a 75% yield in a 50-step process (where a step can indicate the number of layers formed on a wafer), the yield of each individual step must be higher than 99.4%. Even if the yield of individual steps is 95%, the overall process yield will likely be low, around 7-8%.

[0019]

[0034] Maintaining high substrate (i.e., wafer) throughput, defined as the number of substrates processed per hour, is also desirable. High process yield and high substrate throughput can be affected by the presence of defects. This is especially true when operator intervention is required for defect inspection. To maintain high yield and low cost for IC chips, high-performance detection and identification of microscale to nanoscale defects using evaluation systems (such as scanning electron microscopes ("SEM")) is desirable.

[0020]

[0035] A scanning electron microscope (SEM) includes a scanning device and a detector. The scanning device includes an illumination device, which includes an electron source for generating primary electrons and a projection device for scanning a target, such as a substrate, with one or more focused beams of primary electrons. The primary electrons interact with the target, generating interaction products such as signaling particles, e.g., secondary electrons and / or backscattered electrons. Secondary electrons can be thought to have energies up to 50 eV. Backscattered electrons have an energy spectrum from substantially 0 to the maximum energy of the charged particle device, but are conventionally set to electrons (or signaling electrons) with energies greater than 50 eV. The detector captures signaling particles (e.g., secondary electrons and / or backscattered electrons) from the target as the target is scanned, thereby allowing the scanning electron microscope to create an image of the scanned area of ​​the target. The design of the electron-optical device embodying these scanning electron microscope features may have a single beam. For higher throughput, such as for evaluation, depending on the device design, multiple focused beams of primary electrons, i.e., multibeams, may be used. The component beams of a multibeam may be called subbeams or beamlets. Multibeams can scan different parts of a target simultaneously. Therefore, a multibeam evaluation system can evaluate a target much faster than a single-beam evaluation system, for example, by moving the target at a higher speed.

[0021]

[0036] The following describes known implementation configurations of multibeam evaluation devices.

[0022]

[0037] The figures are schematic. Therefore, the relative dimensions of the components in the drawings are exaggerated for clarity. In the following description relating to the drawings, the same or similar reference numbers refer to the same or similar components or entities, and only the differences relating to individual embodiments are described. While the description and drawings relate to electro-optical devices, it should be understood that the embodiments are not used to limit this disclosure to specific charged particles. Therefore, references to electrons and elements mentioned in conjunction with references to electrons throughout this document may be considered more generally to charged particles and elements mentioned in conjunction with references to charged particles, where charged particles are not necessarily electrons.

[0023]

[0038] Next, refer to Figure 1, a schematic diagram showing an exemplary electron beam evaluation apparatus 100, or inspection apparatus. The evaluation apparatus 100 in Figure 1 includes a vacuum chamber 10, a load lock chamber 20, an electron-optical apparatus, an equipment front end module (EFEM) 30, and a controller 50. The electron-optical device 40 may be located inside the vacuum chamber 10. The electron-optical apparatus may comprise the electron-optical device 40 (also known as an electron-optical device, electron beam device, or electron beam device) and a motor-driven or operating stage.

[0024]

[0039] The EFEM30 includes a first load port 30a and a second load port 30b. The EFEM30 may include additional load ports. The first load port 30a and the second load port 30b can accept a Front Opening Unified Pod (FOUP) containing, for example, a substrate (e.g., a semiconductor substrate or a substrate made of other materials) or a target to be evaluated (hereinafter, substrates, wafers, and samples are collectively referred to as "targets"). One or more robotic arms (not shown) within the EFEM30 transport the target to the load lock chamber 20.

[0025]

[0040] A load lock chamber 20 is used to remove gas from around the sample. The load lock chamber 20 may be connected to a load lock vacuum pump system (not shown) that removes gas particles from within the load lock chamber 20. The operation of the load lock vacuum pump system allows the load lock chamber to reach a first pressure below atmospheric pressure. The main chamber 10 is connected to a main chamber vacuum pump system (not shown). The main chamber vacuum pump system removes gas molecules from within the main chamber 10, resulting in a second pressure around the target that is lower than the first pressure. After reaching the second pressure, the target can be transported to an electron-optical device 40, by which it can be evaluated. The electron-optical device 40 may comprise either a single-beam or multi-beam electron-optical apparatus.

[0026]

[0041] The controller 50 is electronically connected to the electron-optical device 40. The controller 50 may be a processor (such as a computer) configured to control the charged particle beam evaluation apparatus 100. The controller 50 may also include processing circuits configured to perform various signal and image processing functions. In Figure 1, the controller 50 is shown outside the structure including the main chamber 10, the load lock chamber 20, and the EFEM 30, but it should be understood that the controller 50 may be part of this structure. The controller 50 may be located within one of the component elements of the charged particle beam evaluation apparatus, or it may be distributed among at least two of these component elements. While this disclosure provides an example of a main chamber 10 housing an electron beam evaluation apparatus, it should be noted that aspects of this disclosure are not limited in their broadest sense to a chamber housing an electron-optical device. Rather, it should be understood that the principles described above may also be applicable to other apparatuses and other apparatus configurations operating under a second pressure.

[0027]

[0042] Next, refer to Figure 2, which is a schematic diagram of an exemplary multi-beam electron-optical device 40 of the evaluation apparatus, for example, the evaluation apparatus 100 of Figure 1. In an alternative embodiment, the evaluation apparatus 100 is a single-beam evaluation apparatus. The electron-optical device 40 may comprise an electron source 201, a beamformer array 372 (also known as a Gun aperture plate, Coulomb aperture array, or pre-subbeamforming aperture array), a focusing lens 310, a radiation source converter (or micro-optical array) 320, an objective lens 331, and a target 308. In one embodiment, the focusing lens 310 is magnetic. (A single-beam evaluation apparatus may have the same features as a multi-beam evaluation apparatus, except that the electron-optical components having array apertures 372, 320 may have a single aperture. The radiation source converter 320 may be replaced by a number of electron-optical components along the beam path.) The target 308 may be supported by a support on a stage. The stage may be motor-driven. The stage moves so that the target 308 is scanned by the incident electrons. The electron source 201, beamformer array 372, and focusing lens 310 may be components of the illumination device, which are included by the electro-optical device 40. The radiation source converter 320 (also known as the radiation source conversion unit), which will be described in more detail below, and the objective lens 331 may be components of the projection device, which are included by the electro-optical device 40.

[0028]

[0043] The electron source 201, beamformer array 372, focusing lens 310, radiation source converter 320, and objective lens 331 are aligned with the primary electron-optic axis 304 of the electron-optic device 40. The electron source 201 can generate a primary beam 302 along approximately the electron-optic axis 304 and with a (virtual or real) radiation source crossover 301S. During operation, the electron source 201 is configured to emit electrons. The electrons are drawn out or accelerated by the extraction electrode and / or anode to form the primary beam 302.

[0029]

[0044] The beamformer array 372 cuts peripheral electrons from the primary electron beam 302 to reduce the resulting Coulomb effect. The primary electron beam 302 can be trimmed by the beamformer array 372 into a specified number of sub-beams, such as three sub-beams 311, 312, and 313. It should be understood that the description is intended to apply to electron-optical devices 40 having any number of sub-beams, such as one, two, or more than three. The beamformer array 372 is configured to shield peripheral electrons to reduce the Coulomb effect during operation.

[0030]

[0045] The radiation source converter 320 is configured to convert the beam transmitted by the beamformer array 372 (including sub-beams, if present) into a sub-beam projected toward the target 308. In one embodiment, the radiation source converter is a unit. Alternatively, the term, radiation source converter, may simply be used as a collective term for a group of components that form a beamlet from a sub-beam.

[0031]

[0046] As shown in Figure 2, in one embodiment, the electro-optical device 40 includes a beam-limiting aperture array 321 having an aperture pattern (i.e., apertures arranged in a certain formation) configured to define the external dimensions of beamlets (or sub-beams) projected toward the target 308. In one embodiment, the beam-limiting aperture array 321 is part of the radiation source converter 320. In an alternative embodiment, the beam-limiting aperture array 321 is part of the beam-upstream system of the main device. In one embodiment, the beam-limiting aperture array 321 splits one or more of the sub-beams 311, 312, and 313 into beamlets, so that the number of beamlets projected toward the target 308 is greater than the number of sub-beams transmitted through the beamformer array 372. In an alternative embodiment, the beam-limiting aperture array 321 maintains the number of sub-beams incident on the beam-limiting aperture array 321, in which case the number of sub-beams may be equal to the number of beamlets projected toward the target 308.

[0032]

[0047] As shown in Figure 2, in one embodiment, the electro-optical device 40 includes a pre-bending deflector array 323 having pre-bending deflectors 323_1, 323_2, and 323_3 for bending sub-beams 311, 312, and 313, respectively. The pre-bending deflectors 323_1, 323_2, and 323_3 can bend the paths of the sub-beams 311, 312, and 313 onto the beam limiting aperture array 321.

[0033]

[0048] The electro-optical device 40 may also include an image-forming element array 322 having image-forming deflectors 322_1, 322_2, and 322_3. Each deflector 322_1, 322_2, and 322_3 is associated with the path of each beamlet. The deflectors 322_1, 322_2, and 322_3 are configured to deflect the path of the beamlet toward the electro-optical axis 304. The deflected beamlets form virtual images (not shown) of the radiation source crossover 301S. In the present embodiment, these virtual images are projected onto a target 308 by an objective lens 331, forming probe spots 391, 392, and 393 thereon. The electro-optical device 40 may also include an aberration compensator array 324 configured to compensate for any aberrations that may exist within each of the sub-beams. In one embodiment, the aberration compensator array 324 includes lenses configured to act on each beamlet. The lenses may take the form of individual lenses or an array. Lenses within the array may act on different beamlets of the multibeam. The aberration compensator array 324 may include, for example, a field curvature compensator array (not shown) having microlenses. The field curvature compensators and microlenses may be configured to compensate for individual subbeams for field curvature aberrations clearly observed within the probe spots 391, 392, and 393, for example. The aberration compensator array 324 may include an astigmatism compensator array (not shown) having microastigmatism correctors. The microastigmatism correctors may be controlled to act on subbeams for astigmatisms otherwise present within the probe spots 391, 392, and 393, for example.

[0034]

[0049] The image-forming element array 322, the aberration compensator array 324, and the pre-bending deflector array 323 may include multiple layers of sub-beam electron-optical devices, such as micro-deflectors, micro-lenses, or micro-astigmatism correctors, some of which may be in form or array form. The beam path may be rotationally controlled. Rotational correction may be applied by magnetic lenses. Rotational correction may be achieved additionally or alternatively by existing magnetic lenses, such as focusing lens mechanisms.

[0035]

[0050] The objective lens 331 focuses the beamlet onto the surface of the target 308; that is, it projects three virtual images onto the target surface. The three images formed on the target surface by the three sub-beams 311-313 form three probe spots 391, 392, and 393 on them. In one embodiment, the deflection angles of the sub-beams 311-313 are adjusted to pass through or approach the front focal point of the objective lens 331 in order to reduce or suppress off-axis aberrations of the three probe spots 391-393. In one configuration, the objective lens 331 is magnetic. Three beamlets are mentioned, but this is merely an example. Any number of beamlets may be present.

[0036]

[0051] In one embodiment, a beam separator (not shown) is provided. The beam separator may be located downstream of the beam of the radiation source converter 320. The beam separator may be, for example, a Wien filter including an electrostatic dipole field and a magnetic dipole field. The beam separator may be located upstream of the beam of the objective lens 331. When in operation, the beam separator may be configured to exert an electrostatic force due to the electrostatic dipole field on individual electrons of the subbeam. In one embodiment, the electrostatic force is equal in magnitude to, but opposite in direction to, the magnetic force exerted on individual primary electrons of the subbeam by the magnetic dipole field of the beam separator. Thus, the subbeam can pass through the beam separator at least substantially straight with a deflection angle of at least substantially zero. The direction of the magnetic force depends on the direction of electron motion, while the direction of the electrostatic force does not depend on the direction of electron motion. Therefore, since secondary electrons and backscattered electrons (or signal electrons) generally move in opposite directions to primary electrons, the magnetic force acting on secondary electrons and backscattered electrons (or signal particles) no longer cancels out the electrostatic force, and as a result, secondary electrons and backscattered electrons moving through the beam separator are deflected far away from the electron-optic axis 304.

[0037]

[0052] In one embodiment, a secondary device (not shown) is provided, comprising a detection element for detecting a corresponding secondary charged particle beam. When the secondary beam is incident on the detection element, the element may generate a corresponding intensity signal output. The output may be led to an image processing system (e.g., controller 50). Each detection element may include an array, which may be in the form of a grid. The array may have one or more pixels, each pixel may correspond to an element of the array. The intensity signal output of the detection element may be the sum of the signals generated by all pixels in the detection element.

[0038]

[0053] In one embodiment, a secondary projection device and its associated electron detection device (not shown) are provided. The secondary projection device and its associated electron detection device can be aligned with the secondary electron optical axis of the secondary device. In one embodiment, a beam separator is positioned to deflect the path of the secondary electron beam toward the secondary projection device. The secondary projection device then focuses the path of the secondary electron beam onto multiple detection areas of the electron detection device. The secondary projection device and its associated electron detection device can record and generate an image of the target 308 using secondary electrons or backscattered electrons (or signal particles).

[0039]

[0054] Such Wien filters, secondary devices, and / or secondary projection devices may be provided within a single-beam evaluation system. Additionally and / or alternatively, a detection device may be located, for example, downstream of the beam of the objective lens, facing the sample during operation. In an alternative configuration, the detector device is located along the path of the charged particle beam toward the sample. Such a configuration does not have a Wien filter, secondary device, and secondary projection device. The detection device may be located, for example, at one or more positions along the path of the charged particle beam toward the sample, for example, facing the sample during operation. Such a detector device may have an aperture and may be annular. Different detector devices may be located along the path of the charged particle to detect signal particles with different characteristics. Electro-optical elements may be arranged and controlled along the path of the charged particle beam, which may include one or more electrostatic plates having an aperture for the path of the charged particle beam, to focus signal particles of each different characteristic onto their respective detector devices at different positions along the path of the charged particle beam. Such electrostatic plates may be arranged in the form of a series of two or more adjacent plates along the path of a charged particle beam.

[0040]

[0055] Any element or set of elements may be interchangeable or in-situ interchangeable within the electro-optical device. One or more electro-optical components within the electro-optical device, in particular those that act on or generate a sub-beam, such as aperture arrays and actuating arrays (e.g., action or manipulation arrays), may include one or more microelectromechanical systems (MEMS). The pre-bending deflector array 323 may be a MEMS. MEMS are miniaturized mechanical and electromechanical elements manufactured using microfabrication techniques. In one embodiment, the electro-optical device 40 comprises apertures, lenses, and deflectors formed as MEMS. In one embodiment, the lenses and manipulators such as deflectors 322_1, 322_2, and 322_3 are controllable passively, actively, as an array, individually, or in groups within the array to control the beamlet of charged particles projected toward the target 308.

[0041]

[0056] In one embodiment, the electro-optical device 40 may include alternative and / or additional components on the charged particle path, such as lenses and other components, some of which have been described earlier with reference to Figures 1 and 2. Examples of such configurations are shown in Figures 3 and 4, which will be described in more detail later. Specifically, the embodiments include an electro-optical device 40 that splits a charged particle beam from a radiation source into a plurality of sub-beams. Each of the plurality of objective lenses may project a sub-beam onto a sample. In some embodiments, a plurality of focusing lenses are provided upstream of the beam from the objective lens. The focusing lenses focus each of the sub-beams to an intermediate focus upstream of the beam in the objective lens. In some embodiments, a collimator is provided upstream of the beam from the objective lens. Correctors for reducing focus errors and / or aberrations may be provided. In some embodiments, such correctors are integrated into the objective lens or positioned directly adjacent to it. Where a focusing lens is provided, such a compensator may be additionally or alternatively integrated within the focusing lens, positioned directly adjacent to it, and / or within the intermediate focal point, or directly adjacent to it. Depending on the embodiment, a macro focusing lens may be used instead of, or in addition to, the focusing lens and collimator to collimate the beam projected toward the objective lens. A detector is provided for detecting charged particles emitted by the sample. The detector may be integrated within the objective lens. The detector may be on the underside of the objective lens so as to face the sample during use. The detector may include, for example, an array of detector elements, which may correspond to an array of beamlets in a multi-beam configuration. Detectors (or detector elements) within a detector array may generate detection signals that can be associated with pixels in the generated image. References to detectors in this specification may be considered to be related to detector arrays. The focusing lens, objective lens, and / or detector may be formed as MEMS or CMOS devices.

[0042]

[0057] Figure 3 is a schematic diagram of another design of an exemplary electro-optical device 40. The electro-optical device 40 may comprise a radiation source 201 and one or more electro-optical assemblies. Alternatively, an electro-optical apparatus comprising the electro-optical device 40 may comprise a radiation source 201. The electro-optical device 40 may comprise an upper beam limiter 252, a collimator element array 271, a control lens array 250, a scan deflector array 260, an objective lens array 241, a beam shaping limiter 242, and a detector array. The source 201 provides a beam of charged particles (e.g., electrons).

[0043]

[0058] The upper beam limiter 252 defines an array of beam limiting apertures. The upper beam limiter 252 may be called an upper beam limiting aperture array or a beam upstream limiting aperture array. The upper beam limiter 252 may include a plate (which may be a plate-like body) having multiple apertures. The upper beam limiter 252 forms a subbeam from the beam of charged particles emitted by the source 201. The portion of the beam that does not contribute to the formation of the subbeam may be blocked (e.g., absorbed) by the upper beam limiter 252 so as not to interfere with the subbeam downstream. The upper beam limiter 252 may be called a subbeam limiting aperture array.

[0044]

[0059] The collimator element array 271 is provided downstream of the beam from the upper beam limiter. Each collimator element collimates its respective sub-beam. The collimator element array 271 may be formed using MEMS fabrication techniques to be spatially compact. In some embodiments illustrated in Figure 3, the collimator element array 271 is the first deflection or focusing electron-optic array element in the beampath downstream of the beam from the radiation source 201. In other configurations, the collimator may take the form of a macrocollimator, either entirely or partially. Such a macrocollimator may be located upstream of the beam from the upper beam limiter 252 to act on the beam from the radiation source before multi-beam generation. Magnetic lenses may be used as macrocollimators.

[0045]

[0060] A control lens array 250 is located downstream of the collimator element array beam. The control lens array 250 includes a plurality of control lenses. Each control lens includes at least two electrodes (e.g., two or three electrodes) connected to its respective potential source. The control lens array 250 may include two or more (e.g., three) plate electrode arrays connected to its respective potential source. The control lens array 250 is associated with the objective lens array 241 (e.g., the two arrays are positioned close to each other and / or mechanically connected to each other and / or controlled together as a unit).

[0046]

[0061] As described above, the control lens array 250 is associated with the objective lens array 241. As stated above, the control lens array 250 can be considered, for example, as part of the objective lens array assembly, providing additional electrodes to the electrodes 242, 243 of the objective lens array 241. The additional electrodes of the control lens array 250 allow for further degrees of freedom in controlling the electron-optical parameters of the subbeam. In one embodiment, the control lens array 250 can be considered as additional electrodes of the objective lens array 241, enabling additional functionality for each of the objective lenses of the objective lens array 241.

[0047]

[0062] For ease of illustration, lens arrays are schematically represented in this specification by an array of elliptical shapes. Each ellipse represents one of the lenses in the lens array. By convention, the elliptical shape is used to represent a lens, often mimicking the biconvex shape adopted for optical lenses. However, it should be understood that, in relation to charged particle configurations such as those discussed herein, lens arrays typically operate electrostatically and therefore may not require any physical elements to adopt a biconvex shape. As mentioned above, a lens array may instead consist of multiple plates having apertures.

[0048]

[0063] A scan deflector array 260 comprising multiple scan deflectors may be provided. The scan deflector array 260 may be formed using MEMS fabrication techniques. Each scan deflector scans over the sample 208 with its respective sub-beam. Thus, the scan deflector array 260 may include a scan deflector for each sub-beam. In one embodiment, a scan deflector described in European Patent No. 2425444 may be used to implement the scan deflector array 260, and that document, in particular with respect to scan deflectors, is incorporated in its entirety by reference. In another configuration, a macroscan deflector may be used upstream of the beam of the upper beam limiter 252. Its function may be similar to or equivalent to that of a scan deflector array. However, it acts on the beam from the radiation source before the multi-beam beamlet is generated.

[0049]

[0064] To guide a subbeam onto the sample 208, an objective lens array 241 is provided, which includes multiple objective lenses. Each objective lens includes at least two electrodes (e.g., two or three electrodes) connected to its respective potential source.

[0050]

[0065] The objective lens array may form part of the objective lens array assembly together with any or all of the scan deflector array 260, the control lens array 250, and the collimator element array 271. The objective lens array assembly may further include a beam shaping limiter 242. The beam shaping limiter 242 defines an array of beam limiting apertures that can shape the cross-section of the electron beam as it strikes the sample surface.

[0051]

[0066] In one configuration, the beam shaping limiter 242 is structurally integrated with the electrodes 302 of the objective lens array 241. Preferably, the beam shaping limiter 242 is positioned in a region of low electrostatic field intensity. Each beam limiting aperture is aligned with the corresponding objective lens in the objective lens array 241. The aperture of the beam shaping limiter 242 may have a smaller diameter than the aperture of at least one other aperture array in the plate stack, for example, including the objective lens array. Each beam limiting aperture has a beam limiting effect, thereby allowing only a selected portion of the subbeam incident on the beam shaping limiter 242 to pass through the beam limiting aperture.

[0052]

[0067] In one embodiment, the electro-optical device 40 is configured to control the objective lens array assembly (for example, by controlling the potential applied to the electrodes of the control lens array 250) such that the focal length of the control lens is greater than the distance between the control lens array 250 and the objective lens array 241.

[0053]

[0068] A power supply may be provided to apply potentials to the electrodes of the control lens of the control lens array 250 and the objective lens of the objective lens array 241, respectively.

[0054]

[0069] A detector array (not shown) is provided to detect charged particles emitted from sample 208. The detected charged particles may include any of the charged particles (e.g., signal particles) detected by a scanning electron microscope, including secondary (e.g., emitted) electrons and / or backscattered electrons from sample 208. The detector may be an array providing a surface of an electron-optical device facing sample 208, e.g., the underside of the electron-optical device. Alternatively, the detector array may be located upstream of the beam on the underside, or, e.g., within or upstream of the objective lens array or control lens array. The elements of the detector array may correspond to beamlets in a multi-beam configuration. The signals generated by the detection of electrons by the elements of the array are transmitted to a processor for image generation. The signals may correspond to pixels in the image.

[0055]

[0070] In other embodiments, both a macro-scan deflector and a scan deflector array 260 are provided. In such a configuration, scanning of the sample surface with a subbeam can be achieved by controlling the macro-scan deflector and the scan deflector array 260 together, preferably synchronously.

[0056]

[0071] In one embodiment, an electron-optical device array 500 is provided, as illustrated in Figure 4. The array 500 may include any of the electron-optical devices described herein. Each electron-optical device focuses its respective multibeams simultaneously onto different regions of the same sample.

[0057]

[0072] Any number of electro-optical devices may be used in array 500. Each electro-optical device in array 500 may consist of any of the configurations described herein when referring to a single electro-optical device, for example, particularly as described with reference to the embodiments shown and described herein with reference to Figure 5. Details of such configurations are described in European Patent Application Publication No. 20184161.6, filed on 6 July 2020. This application is incorporated herein by reference with respect to how objective lenses are incorporated into and adapted for use in a multi-device configuration.

[0058]

[0073] In the example shown in Figure 4, the array 500 includes multiple electro-optical devices of the type described above with reference to Figure 3.

[0059]

[0074] Alternative designs for multibeam electro-optical devices may have the same features as those described with reference to Figure 3, except as described later and shown in Figure 5. An alternative design for a multibeam electro-optical device may comprise a beam-upstream focusing lens array 231 of an objective lens array configuration 241, as disclosed in European Patent Application Publication No. 20158804.3, filed February 21, 2020. That application is incorporated herein by reference insofar as it relates to a description of a multibeam device having a collimator and its components. Such a design does not require a beam-shaping limiter array 242 or an upper beam limiter array 252, because a beam-limiting aperture array associated with the focusing lens array 231 can shape the multibeams 211, 212, and 213.

[0060]

[0075] The paths of the beamlets 211, 212, and 213 diverge far from the focusing lens array 231. The beamlets originate from a source beam with a diverging outer circumference toward the focusing lens array. The focusing lens array 231 focuses the generated beamlets to an intermediate focal point between the focusing lens array 231 and the objective lens array assembly 241 (i.e., toward the control lens array and the objective lens array). The collimator array 271 may be at the intermediate focal point instead of being associated with the objective lens array assembly 241.

[0061]

[0076] In one embodiment of the configuration shown and described with reference to Figure 5, the detector may be located in a similar location within the electro-optical device 40, as described with reference to the electro-optical device in Figure 3 and shown therein. The detector 240 may be integrated within the objective lens array 241 and the control lens array 250 (if present, as it is not shown in Figure 5). The detector may have more than one detector at different locations along the paths of the sub-beams of the multibeam.

[0062]

[0077] The electro-optical device array may have multiple multi-beam devices of this design, as described with reference to the multi-beam device in Figure 3, as shown in Figure 4. Multiple multi-beam devices may be arranged within an array of multi-beam devices. Such a configuration is shown and described in European Patent Application Publication No. 20158732.6, filed on 21 February 2020. This application is incorporated herein by reference with respect to a multi-device configuration of a multi-beam apparatus, characterized by a design of a multi-beam device with a collimator at an intermediate focus. A further alternative design of the multi-beam apparatus comprises multiple single-beam devices.

[0063]

[0078] Figure 6 is a schematic diagram of an alternative exemplary electron-optical device 40, which is a part of the exemplary electron beam evaluation apparatus 100 in Figure 1. The same features as described above are given the same reference numerals. For brevity, such features will not be described in detail with respect to Figure 6. For example, the electron source 201, macrocollimator 270, objective lens array 241, and sample 208 may be as described above.

[0064]

[0079] In one embodiment, the electron-optical apparatus 40 comprises an array of focusing lenses 231. Dozens, hundreds, or thousands of focusing lenses 231 may be present. The focusing lenses 231 include multi-electrode lenses and may have a structure based on European Patent No. 1602121A1, which is incorporated herein by reference in particular with respect to a disclosure of a lens array for splitting an electron beam into a plurality of sub-beams and the array providing a lens for each sub-beam. The array of focusing lenses 231 may take the form of at least two plates that function as electrodes, the apertures of each plate aligned with each other and corresponding to the positions of the sub-beams. At least two of the plates are held at different potentials during operation to achieve a desired lensing effect.

[0065]

[0080] In one configuration, the array of condenser lenses 231 is formed by three plate arrays that have the same energy as electrons enter and exit each lens; this configuration can be called an Einzel lens. Therefore, dispersion occurs only within the Einzel lens itself (between the inlet and outlet electrodes of the lens), thereby limiting off-axis chromatic aberration. When the thickness of the focusing lens is thin, for example a few millimeters, the effect of such aberration is small or negligible.

[0066]

[0081] As described above, in one embodiment, the detector 240 is located between the objective lens array 241 and the sample 208 (and / or the detector 240 is integrated within the objective lens array 241). The detector 240 may face the sample 208. Alternatively, as shown in Figure 6, in one embodiment, the objective lens array 241, which includes multiple objective lenses, is located between the detector 240 and the sample 208.

[0067]

[0082] In one embodiment, the deflector array 95 is located between the detector 240 and the objective lens array 241. In one embodiment, the deflector array 95 includes a Wien filter, so the deflector array may be called a beam separator. The deflector array 95 is configured to provide a magnetic field to separate electrons projected toward the sample 208 from signal electrons, such as secondary electrons, from the sample 208, in order to distinguish, for example, the path of electrons projected toward the sample 208 from the path of signal particles moving away from the sample.

[0068]

[0083] In one embodiment, the detector 240 is configured to detect signal particles by reference to the energy of the electrons, i.e., dependent on the band gap. Such a detector 240 may be called an indirect current detector or a silicon-based detector. Secondary electrons emitted from the sample 208 gain energy from the electric field between the electrodes. The secondary electrodes have sufficient energy once they reach the detector 240. Additionally or alternatively, the detector 240 may include a scintillator. Such a scintillating detector may be configured to detect electrons above a threshold.

[0069]

[0084] In one embodiment, the electro-optical device 40 comprises one or more electro-optical modules 41. In one embodiment, the electro-optical modules 41 or each electro-optical module 41 is field-replaceable. The electro-optical modules 41 can be removed from and / or inserted into the electro-optical device 40 without requiring any substantial dismantling of other parts of the electro-optical device 40. That is, the electro-optical modules 41 can be removed from and / or inserted into the electro-optical device 40.

[0070]

[0085] Figure 7 schematically illustrates how the electron-optical device 40 comprises one or more electron-optical modules 41a, 41b, 41c. Figure 7 is a schematic diagram of an alternative exemplary electron-optical device which is part of the exemplary electron beam evaluation apparatus of Figure 1. Such an electron-optical device may have at least the same or at least similar components as those shown and described with reference to Figure 5.

[0071]

[0086] The electro-optical device 40 is configured to project a multibeam of electrons along a multibeam path toward the sample 208. The features of the electro-optical device 40 described above are not described again herein to avoid repetition. In one embodiment, the electro-optical device 40 comprises, as described above, a radiation source 201, an array of focusing lenses 231, an array of deflectors 271, a control lens array 250, an array of scanning deflectors, and an objective lens array 241.

[0072]

[0087] As shown in Figure 7, in one embodiment, the electron-optical device 40 includes a tube 88 (which may also be called a liner tube or booster tube). In one embodiment, the tube 88 is positioned to surround a multibeam path. The tube 88 surrounds the multibeam path, for example, along the primary axis of the electron-optical device 40, i.e., when viewed in the direction of the electron beam. In one embodiment, the tube 88 is configured to surround only a portion of the multibeam path, i.e., a portion of the multibeam path along the length of the multibeam path. For example, in one embodiment, the tube 88 surrounds the portion of the multibeam path from the radiation source 201 to just above the array of focusing lenses 231. The tube 88 may surround an alternative portion of the multibeam path, e.g., its length.

[0073]

[0088] Tube 88 can be at a high voltage. For example, the first potential difference can be greater than 100V, optionally at least 200V, optionally at least 500V, optionally at least 1kV, optionally at least 2kV, optionally at least 5kV, optionally at least 10kV, optionally at least 20kV, optionally at least 30kV, and optionally at least 60kV. When the charged particle is negatively charged, for example, an electron, tube 88 can be at a high positive voltage. Alternatively, when the charged particle is positively charged, tube 88 can be at a high negative voltage. Tube 88 is configured to allow electrons from the electron beam to travel at high energy through the electron-optical device 40 (i.e., from the radiation source 201 to the sample 208).

[0074]

[0089] As shown in Figure 7, in one embodiment, the tube 88 includes at least three sections 88a, 88b, and 88c, which may be called the beam upstream section 88a, the intermediate section 88b, and the beam downstream section 88c. In one embodiment, a subbeam of electrons (i.e., a multibeam of electrons) is generated beam upstream at the end of the tube 88, i.e., beam upstream at the end of the most beam downstream section 88c of the tube 88. Each section 88a, 88b, and 88c of the tube 88 has a terminal at its upper end and a terminal at its lower end.

[0075]

[0090] As shown in Figure 7, in one embodiment, the electro-optical device 40 comprises one or more electro-optical modules 41. In one embodiment, the beam upstream module 41a includes an array of focusing lenses 231. In one embodiment, the intermediate module 41b includes an array of deflectors 271. In one embodiment, the beam downstream module 41c includes a control lens array 250 and an objective lens array 241. The beam downstream module 41c may further include an array of scanning deflectors and / or detectors. Such a modular concept can be applied to different electro-optical components of the electro-optical device 40 shown and described with reference to Figures 3 to 6.

[0076]

[0091] In one embodiment, the electro-optical module 41 is positioned between sections 88a, 88b, and 88c of the tube 88. The ends of sections 88a, 88b, and 88c of the tube 88 may be inserted into the electro-optical module 41. Alternatively, the electro-optical module 41 may include sections 88a, 88b, and 88c of the tube 88.

[0077]

[0092] The electron-optical device 40 may be a component of an evaluation apparatus (for, for example, inspection, measurement, measurement-inspection, or any other type of evaluation), or part of an electron beam lithography apparatus or other type of charged particle-induced sample patterning apparatus. Multibeam charged particle apparatuses can be used in a number of different applications, including scanning electron microscopy as well as electron microscopy in general and lithography.

[0078]

[0093] The electro-optical device 40 may include an electro-optical module 41 for acting on an electron beamlet, as shown in Figure 8. For example, the electro-optical module 41 may include one or more of the following (in an unrestricted list): an objective lens array 241, and / or a focusing lens array 231, and / or a collimator element array 271, and / or individual beam correctors, and / or deflectors, and / or a Wien filter array. Specifically, the electro-optical module 41 may include an objective lens 331, and / or a focusing lens 310, and / or a control lens 250.

[0079]

[0094] The electro-optical module 41 is configured to provide a potential difference between two or more plates (or substrates), for example, between opposing surfaces of adjacent plates along the path of one or more beams. An electrostatic field is generated between the plates acting as electrodes. The electrostatic field results in an attractive force between the two plates. As the potential difference increases, the attractive force can be increased.

[0080]

[0095] Figure 8 schematically shows the electron-optic module 41. The electron-optic module 41 is configured to guide electrons toward the sample position along at least one beampath. In the orientation shown in Figure 8, at least one beampath extends vertically from top to bottom through the center of the electron-optic module 41. There may be one beampath corresponding to a single electron beam. Alternatively, there may be multiple beampaths corresponding to multiple electron subbeams of a multi-beam system.

[0081]

[0096] As shown in Figure 8, in one embodiment, the stack 55 of the electron-optic module 41 includes a plurality of planar elements arranged across the beam path. In one embodiment, one or more of the planar elements are electron-optic plates 60. The electron-optic plates 60 are configured to act on one or more electron beams. As shown in Figure 8, in one embodiment, all of the planar elements are electron-optic plates 60. Alternatively, one or more of the planar elements may be planar elements other than electron-optic elements. For example, one or more of the planar elements may be elements that do not require a voltage to be applied to them in order to perform their function, or the planar elements may require a voltage to be applied to them such that there is a substantially zero potential difference between the element and adjacent elements along the beam path. An example is a planar element that is a beam-limiting aperture array containing apertures sized to shape the electron beam. For example, apertures may allow an electron beam of a particular shape to pass through while preventing other electrons from passing through the beam-limiting aperture array. As a further alternative, a planar element configured to shape an electron beam may also have a potential difference to planar elements upstream and / or downstream of the beam, in addition to its beam-shaping function, so that the electromagnetic field affects the electron beam.

[0082]

[0097] As shown in Figure 8, in one embodiment, the electro-optic module 41 includes one or more spacers 70. The spacers 70 are configured to mechanically support planar elements. As shown in Figure 8, in one embodiment, the spacers 70 are configured to mechanically separate planar elements such as electro-optic plates 60 from each other. In one embodiment, the spacers 70 are configured to electrically isolate planar elements such as electro-optic plates 60 from each other. However, it is not essential that the spacers 70 provide electrical isolation. For example, it may be that two adjacent electro-optic plates 60 are configured to operate at the same voltage (i.e., without a potential difference between them), in which case electrical isolation may not be necessary. In one embodiment, one or more pairs of adjacent planar elements are placed directly next to each other, i.e., without intermediate spacers 70. The spacers 70 are an optional feature.

[0083]

[0098] The electron beam is configured to pass through the beam region 62 of the electron-optic module 41. As shown in Figure 8, the beam region 62 may be located within the central portion of the electron-optic module 41, and such a central portion may be located at the center of the electron-optic module 41. The beam region 62 may be located approximately at the center when viewed in a direction parallel to at least one beam path. The beam region 62 is located at the center when viewed in a direction perpendicular to the plane of the planar element.

[0084]

[0099] In one embodiment, the electro-optical module 41 is contained within an electro-optical device 40, for example, an electro-optical device 40 as shown in Figures 2 to 7. In one embodiment, the electro-optical module 41 is field-replaceable. The electro-optical module 41 can be removed from and / or inserted into the electro-optical device 40 without requiring any substantial dismantling of other parts of the electro-optical device 40. That is, the electro-optical module 41 can be removed from and / or inserted into the electro-optical device 40.

[0085]

[0100] In one embodiment, the electro-optical module 41 comprises an objective lens assembly including an objective lens array 241. The electro-optical module 41 may further comprise a control lens array 250, a detector 240, and / or a deflector array. In an alternative embodiment, the electro-optical module 41 may be a focusing lens assembly or a collimator array assembly. The electro-optical module 41 may comprise a focusing lens array 231 and / or a collimator array 271. The electro-optical module 41 may further comprise, for example, one or more of a deflector array and a beam limiting aperture array.

[0086]

[0101] Figure 9 is a schematic diagram of the electron-optic module 41. The electron-optic module 41 may be, for example, a part of the electron-optic device 40 shown in any of Figures 2 to 7. The electron-optic module 41 is for the electron-optic device 40. In one embodiment, the electron-optic device 40 is configured to guide the electron beam along the beam path toward the sample position. In one embodiment, the electron-optic module 41 is configured to guide the electron beam along the beam path toward the sample position.

[0087]

[0102] As shown in Figure 9, in one embodiment, the electro-optical module 41 comprises a stack 55. The stack 55 may have the features described above with reference to Figure 8. In one embodiment, the stack 55 includes one or more electro-optical plates 60. In one embodiment, one or more electro-optical plates 60 are arranged across the beam path. In the orientation shown in Figure 9, the beam path extends vertically from top to bottom. The beam path may extend substantially centrally with respect to the width direction of the electro-optical plate 60 shown in Figure 9. Figure 9 shows a cross-sectional view of the electro-optical module 41. The cross-section is taken perpendicular to the plane of the electro-optical plate 60.

[0088]

[0103] In the mechanism shown in Figure 9, the stack 55 includes four electron-optical plates 60. In alternative embodiments, the stack 55 may include one or fewer, optionally two or fewer, and optionally three or fewer electron-optical plates 60. In one embodiment, the stack 55 includes five electron-optical plates 60, or more than five electron-optical plates 60 (as shown, for example, in Figure 8). In one embodiment, the electron-optical plates 60 are configured to act on the electron beam.

[0089]

[0104] As described above, in one embodiment, the electron beam is a multibeam comprising multiple electron subbeams. In an alternative embodiment, the electron beam is a single electron beam. The electron-optical plate 60 has a functional relationship with the electron beam. As described elsewhere in this specification, the electron beam may represent, for example, multiple electron beams in a beam grid.

[0090]

[0105] As shown in Figure 9, in one embodiment, the electro-optic module 41 includes a shielding mechanism 80. In one embodiment, the shielding mechanism 80 is provided in addition to the stack 55. In one embodiment, the stack 55 includes electro-optic components such as electro-optic plates 60 and spacers 70. In one embodiment, the shielding mechanism 80 includes at least one of the electro-optic plates 60. The shielding mechanism 80 may alternatively be called, for example, a shielding box, an electric field shielding box, or a grounding box.

[0091]

[0106] As shown in Figure 9, in one embodiment, the shielding mechanism 80 includes an upstream beam electrostatic shield 71. The upstream beam electrostatic shield 71 is positioned across the beam path. In one embodiment, the upstream beam electrostatic shield 71 is located upstream of one or more electro-optical plates 60. As shown in Figure 9, in one embodiment, the shielding mechanism 80 includes a downstream beam electrostatic shield 72. The downstream beam electrostatic shield 72 is positioned across the beam path. In one embodiment, the downstream beam electrostatic shield 72 is located downstream of one or more electro-optical plates 60.

[0092]

[0107] In one embodiment, the beam upstream electrostatic shield 71 is located on the upper or uppermost surface of the electro-optic module 41. In another embodiment, the beam downstream electrostatic shield 72 is provided on the lower or lowermost surface of the electro-optic module 41.

[0093]

[0108] As shown in Figure 9, in one embodiment, the upstream electrostatic shield 71 is substantially planar. In one embodiment, the downstream electrostatic shield 72 is substantially planar. In one embodiment, the upstream electrostatic shield 72 is substantially parallel to the electron-optic plate 60. In one embodiment, the downstream electrostatic shield 72 is substantially parallel to the electron-optic plate 60. The electron-optic plate 60 is positioned between the upstream electrostatic shield 71 and the downstream electrostatic shield 72 (in the direction along the beam path).

[0094]

[0109] In one embodiment, the shielding mechanism 80 is configured to prevent electrical breakdown between the electro-optic module 41 and external components of the electro-optic module 41. For example, electrical breakdown between the electro-optic plate 60 and the sample 208 or an electrical cable can be prevented.

[0095]

[0110] In one embodiment, the electron-optical plate 60 is configured to form at least one electrostatic field. The electrostatic field can act on the electron beam. For example, the electrostatic field may be formed between the surfaces of adjacent electron-optical plates 60. In one embodiment, the controller 50 is configured to control the potential applied to the electron-optical plate 60 in order to control the electrostatic field formed by the electron-optical plate 60. In one embodiment, the controller 50 is configured to control the potential applied to the electron-optical plate 60 in order to control the electron beam.

[0096]

[0111] In one embodiment, the shielding mechanism 80 is configured to confine an electrostatic field within the electron-optic module 41. An electrostatic field may be generated, for example, when one or more electron-optic plates 60 act on the electron beam along the beam path. The shielding mechanism 80 can function to some extent as a Faraday cage by reducing the electromagnetic field or preventing the electromagnetic field from entering or leaving the stack 55.

[0097]

[0112] In one embodiment, the shielding mechanism 80 is implemented to confine the electric field within the electro-optic module 41 and, optionally, within the stack 55. The shielding mechanism 80 may be configured to reduce or eliminate the electric field between the stack 55 and its surroundings. In one embodiment, at least one electric field may remain between the stack 55 and its surroundings. For example, in one embodiment, the electric field may remain due to the bias potential on sample 208.

[0098]

[0113] One embodiment of the present invention is expected to reduce the risk of discharge between the stack 55 and its surroundings. By confining the electric field within the electro-optical module 41, the electric field is reduced or eliminated, thereby reducing the risk of discharge.

[0099]

[0114] One embodiment of the present invention is expected to achieve a more compact electro-optical device 40. By providing a shielding mechanism 80, the stack 55 can be positioned closer to its surroundings without excessively increasing the risk of discharge to and from the surroundings. A more compact design can be achieved.

[0100]

[0115] One embodiment of the present invention is expected to achieve increased design freedom for the components surrounding the stack 55. For example, the components surrounding the stack 55 may be allowed to have sharp corners without excessively increasing the risk of discharge between the stack 55 and its surroundings.

[0101]

[0116] One embodiment of the present invention is expected to reduce gas emissions. For example, by providing a shielding mechanism 80, the surface area of ​​insulating material (e.g., potting material) exposed to the outside of the stack 55 can be reduced. Such insulating materials can generally be more prone to gas emissions. By reducing such exposed surfaces of insulating material, gas emissions from the stack can be preferably reduced.

[0102]

[0117] As shown in Figure 9, in one embodiment, the beam upstream electrostatic shield 71 and the beam downstream electrostatic shield 72 are provided at the top and bottom of the electro-optic module 41. The beam upstream electrostatic shield 71 and the beam downstream electrostatic shield 71 may be configured to confine the electrostatic shield within the stack 55. One embodiment of the present invention is expected to mitigate problems caused by the use of high voltages in the electro-optic module 41 and / or neighboring modules. Such neighboring modules may be physically isolated (i.e., physically separated from the electro-optic module 41). Alternatively, such neighboring modules may be physically mounted on the electro-optic module 41, which may have a potential similar to that of the shielding mechanism 80.

[0103]

[0118] As shown in Figure 9, in one embodiment, the shielding mechanism 80 is configured to extend across the beam path beyond one or more electro-optical plates 60. This is shown in Figure 9, where the shielding mechanism 80 is wider than the electro-optical plates 60. As shown in Figure 9, in one embodiment, the upstream beam electrostatic shield 71 and the downstream beam electrostatic shield 72 extend across the beam path beyond one or more electro-optical plates 60. The greater lateral extension of the shielding mechanism 80 can reduce the possibility of undesirable electrical breakdown between the stack 55 and the external components. In one embodiment, the outer diameter of the upstream beam electrostatic shield 71 and / or the downstream beam electrostatic shield 72 is at least 10%, optionally at least 20%, optionally at least 50%, and optionally at least 100% larger than the outer diameter of one or more electro-optical plates 60.

[0104]

[0119] As shown in Figure 9, in one embodiment, the electro-optical module 41 comprises insulators 76, 77. The insulators 76, 77 are located on the inward-facing surface of the shielding mechanism 80. For example, in one embodiment, the beam-upstream insulator 76 is located on the inward-facing surface of the beam-upstream electrostatic shield 71. In one embodiment, the beam-downstream insulator 77 is located on the inward-facing surface of the beam-downstream electrostatic shield 72. The inward-facing surface is the surface facing inward of the electro-optical module 41. The insulators 76, 77 are provided to prevent electrical breakdown between the shielding mechanism 80 and other parts of the electro-optical module 41, such as one or more of the electro-optical plates 60 and / or one or more electrical connectors 84.

[0105]

[0120] As shown in Figure 9, in one embodiment, at least an aperture 74 is defined within the shielding mechanism 80. In one embodiment, at least one of the beam upstream electrostatic shield 71 and the beam downstream electrostatic shield 72 includes an aperture 74 for the beam path. For example, Figure 9 shows that the beam upstream electrostatic shield 71 includes such an aperture 74. The beam path extends through the aperture 74. As shown in Figure 9, in one embodiment, the aperture 74 is defined within a radially inward circumferential surface 73. In one embodiment, the aperture 74 is central within the electro-optical module 41. For example, the aperture 74 may be central with respect to the stack 55. In one embodiment, the radially inward circumferential surface 73 faces the aperture 74 around the beam path.

[0106]

[0121] By providing an opening 74, the shielding mechanism 80 can be opened to some extent (i.e., not completely closed). Such an opening 74 may be provided at the top of the stack 55 and / or at the bottom of the stack 55, as shown in Figure 9. In one embodiment (for example, as will be described in more detail below and shown, for example, in Figures 12, 15, and 16), such an opening 74 allows, for example, the entry of a tube 88 into the volume of the stack.

[0107]

[0122] Figure 10 is a schematic diagram of an alternative mechanism for the electro-optical module 41. The electro-optical module 41 may be, for example, a part of the electro-optical device 40 shown in any of Figures 2 to 7. To reduce redundant explanation, the features of the electro-optical module 41 shown in Figure 10, which are substantially the same as the corresponding features described above, will not be described again below, for example, in the following text.

[0108]

[0123] As shown in Figure 10, in one embodiment, the electro-optic module 41 includes at least one electrical connector 84. The electrical connector 84 is configured to connect at least one of the electro-optic plates 60 to a voltage source. The voltage source can supply a voltage so that the electro-optic plate 60 reaches a target potential. In one embodiment, a controller 50 is configured to control the voltage supplied to the electro-optic plate 60 through the electrical connector 84 by the voltage source.

[0109]

[0124] In one embodiment, the voltage source is configured to supply potential such that the potential difference between at least one of the electro-optical plates 60 and the shielding mechanism 80 is at least 1kV, optionally at least 2kV, optionally at least 5kV, optionally at least 10kV, optionally at least 20kV, and optionally at least 30kV. In another embodiment, the voltage source is configured to supply potential such that the potential difference between at least one of the electro-optical plates 60 and the shielding mechanism 80 is in the range of approximately 1kV to approximately 40kV.

[0110]

[0125] As shown in Figure 10, in one embodiment, the shielding mechanism 80 is configured to extend in a direction across the beam path and protrude beyond at least one electrical connector 84. As shown in Figure 10, in one embodiment, the shielding mechanism 80 is configured to protrude beyond at least one electrical connector 84 upstream of the beam of the stack 55 and downstream of the beam of the stack 55.

[0111]

[0126] At least one electrical connector 84 may form an electrostatic field, for example, during operation. In one embodiment, the shielding mechanism 80 is configured to shield components located outside the electro-optic module 41 from discharge with at least one electrical connector 84. Such external components may be surfaces whose shape corresponds to the surface of the module 41. The surface of the external component faces the surface of the module, for example, the surface of the shielding mechanism 80. The outer surface and the shielding mechanism 80 face each other and, for example, are coplanar with respect to each other. The outer surface may define a chamber wall defining the device 40. A small displacement or gap may exist between the outer surface and the shielding mechanism 80. In one embodiment, the shielding mechanism 80 is configured to shield against electrostatic fields generated within the electro-optic module 41.

[0112]

[0127] As shown in Figure 10, in one embodiment, the shielding mechanism 80 includes an upstream beam electrostatic shield 71 positioned across the beam path so as to extend upstream of the beam of the stack 55 in a direction transverse to the beam path. The surfaces of external components may face the surfaces of electrostatic shields, such as the upstream beam electrostatic shield 71. In one embodiment, the shielding mechanism 80 includes a downstream beam electrostatic shield 72 configured to extend downstream of the beam of the stack 55 in a direction transverse to the beam path. In one embodiment, the shielding mechanism 80 extends radially (i.e., in a direction transverse to the beam path) to shield at least one electrical connector 84. In one embodiment, the shielding mechanism 80 extends in a direction transverse to the beam path to prevent electrical breakdown between at least one electrical connector 84 and external components of the electro-optical module 41.

[0113]

[0128] In one embodiment, the upstream electrostatic shield 71 and the downstream electrostatic shield 72 are configured to have a common potential. The potential applied to the upstream electrostatic shield 71 may be substantially the same as the potential applied to the downstream electrostatic shield 72. In one embodiment, the upstream electrostatic shield 71 and the downstream electrostatic shield 72 are electrically connected to each other. Alternatively, the upstream electrostatic shield 71 may be electrically isolated from the downstream electrostatic shield 72. The upstream electrostatic shield 71 may be connected to a first voltage source such that the upstream electrostatic shield 71 is at a first potential. The downstream electrostatic shield 72 may be connected to a second voltage source. The second voltage source may be configured to apply the first potential to the downstream electrostatic shield 72. Alternatively, there may be a small difference between the potentials supplied to the upstream electrostatic shield 71 and the downstream electrostatic shield 72.

[0114]

[0129] In one embodiment, the upstream electrostatic shield 71 is mechanically and electrically connected to the downstream electrostatic shield 72. For example, in one embodiment, an electrical connection 87 is provided between the upstream electrostatic shield 71 and the downstream electrostatic shield 72. In one embodiment, the electrical connection 87 includes fasteners such as a conductive adhesive (e.g., conductive glue), a conductive clamp, and / or a screw. By providing the upstream electrostatic shield 71 and the downstream electrostatic shield 72 at the same or similar potentials, the electric field can be confined within the stack 55. The electrical connection 87 is shown by a dashed line in Figure 10. Furthermore, the potentials of the opposing surfaces and outer surfaces of the electrostatic shields, such as the upstream electrostatic shield 71, can be configured to be the same or at least similar. Because these opposing surfaces have the same or substantially similar potentials, the risk of undesirable discharge to the outer surface can be reduced.

[0115]

[0130] As shown in Figure 9, in one embodiment, at least a portion of the shielding mechanism 80 includes a conductive layer, such as a conductive coating, on the insulators 76, 77. For example, as shown in Figure 9, in one embodiment, the beam upstream electrostatic shield 71 includes a conductive coating (i.e., a conductive layer) on the beam upstream insulator 76. The beam upstream insulator 76 may be planar. In one embodiment, the beam upstream insulator 76 is substantially parallel to the electron-optical plate 60.

[0116]

[0131] As shown in Figure 10, in one embodiment, at least a portion of the beam-downstream electrostatic shield 72 includes a layer, such as a coating, on the beam-downstream insulator 77. The coating may be conductive. The beam-downstream insulator 77 may be planar. The beam-downstream insulator 77 may be substantially parallel to one or more electron-optical plates 60. The shielding mechanism 80 may be formed by two large plates that function as insulators, for example, two insulating plates having a conductive outer surface, for example, as an outer coating, i.e., a beam-upstream insulator 76 and a beam-downstream insulator 77 (which may be spacers). Note: Further references to coatings in this specification can be considered as providing a conductive surface and / or a conductive layer, for example, of a limited thickness.

[0117]

[0132] One embodiment of the present invention is expected to reduce voltage instability and / or partial discharge. By providing a conductive coating to form at least a portion of the shielding mechanism 80, the possibility of air gaps or voids inside the shielding mechanism 80 is reduced. The conductive coating can be applied to the insulators 76, 77 such that there are substantially no gaps or voids between the conductive coating and the insulators 76, 77. Air gaps or voids can otherwise lead to an increase in the local electric field, which can lead to partial discharge and, consequently, voltage instability.

[0118]

[0133] It is not essential that at least a portion of the shielding mechanism 80 be provided as a conductive coating. As shown in Figure 9, in one embodiment, the shielding mechanism 80 may be provided by one or more conductive plates. For example, the beam downstream electrostatic shield 72 may be provided as a conductive plate adjacent to the beam downstream insulator 77. In one embodiment, an electrically insulating filler material, such as a potting material, may be provided between such a conductive plate forming the beam downstream electrostatic shield 72 and the beam downstream insulator 77. The filler material can reduce the occurrence of air gaps or voids between the beam downstream electrostatic shield 72 and the beam downstream insulator 77. Similarly, in one embodiment, the beam upstream electrostatic field 71 is formed as a conductive plate adjacent to the beam upstream insulator 76.

[0119]

[0134] As shown in Figure 10, in one embodiment, at least one electrical connector 84 is configured to electrically connect an electrical cable 85 to one or more of the electro-optical plates 60. The electrical cable 85 may be a high-voltage cable. In one embodiment, the electrical cable 85 is unshielded. For example, the electrical cable 85 may only provide internal insulation around the electrical conductors. As shown in Figure 10, in one embodiment, the electrical cable 85 is configured to electrically connect the electrical connector 84 to a cable shield end 86. In one embodiment, the cable shield end 86 is a high-voltage cable shield end.

[0120]

[0135] As shown in Figure 10, in one embodiment, the shielding mechanism 80 has an opening at the cable inlet point in the side view shown in Figure 10 (i.e., between the beam upstream electrostatic shield 71 and the beam downstream electrostatic shield 72). In one embodiment, the cable shield end 86 has the same or similar potential as the shielding mechanism 80. It is expected that there is no or very little electric field leakage from the shielding mechanism 80. That is, the electric field is substantially contained by the shielding mechanism 80, for example. As shown in Figure 10, in one embodiment, the shielding mechanism 80 extends across the beam path to the cable shield end 86.

[0121]

[0136] In one embodiment, the insulators 76, 77 include glass. For example, the beam upstream insulator and / or beam downstream insulator 77 is a glass plate. A conductive coating may be applied to the outward surface of the glass plate to function as part of the shielding mechanism 80. In one embodiment, an insulating material such as insulating potting is provided to fill any gap between the glass plate and the electro-optic plate 60 and / or at least one electrical connector 84. Note: Although two elements, a glass plate and an insulating material, have been described, alternative well-known mechanisms may be used so that the volume of the glass plate and potting is insulating, for example they may be integrated with each other in a monolithic element, for example. This can help prevent an increase in the electric field in any gap near the electro-optic plate 60 and / or at least one electrical connector 84. Such a potting material 83 is shown in Figure 10, for example, between the electrical connector 84 and the beam upstream insulator 76 and beam downstream insulator 77.

[0122]

[0137] As shown in Figure 10, in one embodiment, a gap is provided between the electrical cable 85 and the insulators 76 and 77. Since both the outer surface of the electrical cable 85 and the opposing surfaces of the insulators 76 and 77 are electrically insulating, it is not necessary to fill such a gap with potting.

[0123]

[0138] As described above, in alternative embodiments, the shielding mechanism 80 is provided by a conductive plate instead of a conductive coating on an insulator. In one embodiment, an insulating material is provided on the inward-facing surface of the conductive plate to reduce the possibility of discharge to the charged portion in the stack 55.

[0124]

[0139] In one embodiment, a filler material, such as a potting material 83, is included between at least a portion of one or more surfaces of the shielding mechanism 80 and the stack 55. The filler material, such as the potting material 83, is provided to substantially avoid a gap between the shielding mechanism 80 and the insulators 76, 77.

[0125]

[0140] As shown in Figure 10, in one embodiment, the electro-optical plate 60 of the stack 55 includes a beam downstream plate 63. The beam downstream plate 63 may be an electrode of an electrostatic lens composed of two or more plates, such as an objective lens. Therefore, the beam downstream plate may be called the objective lens lower electrode, for example, by referring to the fact that the plate includes a portion of the objective lens and the position of the beam downstream plate 63 in the objective lens relative to the beam path. As shown in Figure 10, in one embodiment, the beam downstream plate 63 is electrically connected to a conductive coating on the beam downstream insulator 77. In a different configuration, the beam downstream plate has an electrical connection separate from the conductive surface, for example, of the conductive coating. The beam downstream plate 63 may be set to a different potential from the conductive surface.

[0126]

[0141] In one embodiment, the shielding mechanism 80 includes one or more of the electro-optical plates 60 of the stack 55. For example, at least one of the beam upstream electrostatic shield 71 and the beam downstream electrostatic shield 72 may include at least one of the electro-optical plates 60. For example, in the configuration shown in Figure 10, the beam downstream plate 63, which is one of the electro-optical plates 60 of the stack 55, is included as part of the beam downstream electrostatic shield 72. The beam downstream plate 63 may be at the same potential as the rest of the shielding mechanism 80. In one embodiment, the electro-optical plates included in the shielding mechanism 80, such as the beam downstream plate 63, reduce the extent to which the shielding mechanism 80 is open to, for example, the external environment in order to contain the electrostatic field. The beam downstream plate 63 substantially closes what would otherwise be another opening 74 in the beam downstream electrostatic shield 72, or at least reduces the open area of ​​the opening 74 in the beam downstream electrostatic shield 72.

[0127]

[0142] As shown in Figure 9, in one embodiment, the stack 55 includes at least one spacer 70. In one embodiment, the spacer 70 is configured to support and / or electrically isolate at least one of the electro-optical plates 60. For example, in one embodiment, individual spacers 70 are positioned between pairs of electro-optical plates 60.

[0128]

[0143] In one embodiment, the shielding mechanism 80 includes at least one spacer, such as a beam upstream insulator 76 included in the beam upstream electrostatic shield and / or a beam downstream insulator 77 included in the beam downstream electrostatic shield.

[0129]

[0144] As shown in Figure 10, in one embodiment, at least one of the spacers 70 is positioned around one of the electron-optical plates 60. Such a spacer 75 may be called a radial spacer. For example, in the configuration shown in Figure 10, the radial spacer 75 is positioned radially around the beam downstream plate 63. In one embodiment, the radial spacer 75 is radially spaced away from the beam downstream plate 63. As shown in Figure 10, in one embodiment, the radial spacer 75 is positioned around one of the electron-optical plates 60 such that the electron-optical plate 60 (e.g., the beam downstream plate 63) is positioned between the beam path and the radial spacer 75.

[0130]

[0145] As shown in Figure 10, in one embodiment, the radial spacer 75 is configured to separate the electron-optical plate 60 (e.g., the beam-downstream plate 63) from another component of the electron-optical module 41 in the direction along the beam path. In one embodiment, the radial spacer 75 is configured to separate the electron-optical plate 60 (e.g., the beam-downstream plate 63) from another electron-optical plate. For example, as shown in Figure 10, in one embodiment, the radial spacer 75 is configured to separate the beam-downstream plate 63 from the detector 240. The detector 240 may be an electron-optical plate.

[0131]

[0146] As shown in Figure 10, in one embodiment, the detector 240 and the radial spacer 75 (may also be called the detector spacer) are mounted on the outside of the shielding mechanism 80. In one embodiment, the detector 240 is at the same potential as the shielding mechanism 80. It is desirable that the detector 240 and the shielding mechanism be at the same potential. The detector 240 can be considered as part of the shielding mechanism 80. In one embodiment, the radial spacer 75 is conductive. The radial spacer 75 can electrically connect the detector 240 to a conductive coating provided on the beam downstream insulator 77.

[0132]

[0147] By providing that the beam downstream plate 63 is electrically connected to the conductive coating, the beam downstream plate 63 can have a target potential applied to it without requiring a separate electrical connection for the beam downstream plate 63. In an alternative embodiment, the beam downstream plate 63 is electrically isolated from the conductive coating. In one embodiment, a separate electrical connection is provided between the beam downstream plate 63 and the voltage source.

[0133]

[0148] The provision of radial spacers 75 is not mandatory. Figure 11 is a schematic diagram of a modified version of the electro-optic module 41 shown in Figure 10. As shown in Figure 11, in one embodiment, radial spacers are not provided. Instead, spacers 70 on the beam downstream side of the electro-optic module 41 are provided between the beam downstream plate 63 and the detector 240. The shielding mechanism 80 is configured to extend radially.

[0134]

[0149] As shown in Figure 10, in one embodiment, at least one of the electron-optical plates 60 includes a detector 240 positioned across the beam path. In one embodiment, the detector 240 is configured to detect electrons from the sample position. In one embodiment, the detector 240 includes a detector array. In one embodiment, the detector array includes detector elements. Figure 10 is an exemplary embodiment. In different embodiments, the detector 240 may be positioned in one or more different locations within the stack 55.

[0135]

[0150] Figure 12 is a schematic diagram of the electro-optical module 41. The electro-optical module 41 shown in Figure 12 can be considered a modified version of the electro-optical module 41 shown in Figure 10. However, in different configurations, the new features shown and described with reference to Figure 12, compared to Figure 10, may be applied to the configuration shown and described with reference to Figure 11.

[0136]

[0151] As shown in Figure 12, in one embodiment, the electro-optic module 41 comprises a tube 88 (or tube portion). In one embodiment, the tube 88 is configured to surround a portion of the beam path. In one embodiment, the tube portion is in contact with the electro-optic plate 60. In one embodiment, the tube 88 is connected to one of the electro-optic plates 60, for example, to the beam upstream plate 64. In one embodiment, a gap is provided between two sections of the tube 88. Alternatively, as shown in Figure 12, the tube 88 may be physically separated from the electro-optic plate 60 of the stack 55.

[0137]

[0152] As shown in Figure 12, in one embodiment, the tube 88 is configured to protrude through an opening 74. The opening 74 is defined within the shielding mechanism 80. In one embodiment, the opening 74 is defined within one of the beam upstream electrostatic shield 71 and the beam downstream electrostatic shield 72. In one embodiment, the tube 88 is positioned away from the surface of the opening 74. For example, the tube 88 may be separated from the inward circumferential surface 73 that defines the opening 74, i.e., distal. In one embodiment, the tube 88 is conductive. As shown in Figure 12, in one embodiment, the shielding mechanism 80 extends further from the beam path than the conductive tube 88 and stack 55. The tube 88 may be a portion of the tube 88 shown and described with reference to Figure 7 (e.g., its sections 88a, 88b, and 88c). The shielding mechanism 80 may extend further from the beam path than the tube 88 and stack 55, for example, orthogonally from the beam path.

[0138]

[0153] As shown in Figure 12, in one embodiment, the tube 88 is separated from the electro-optic module 41. As shown in Figure 12, in one embodiment, the tube 88 is separated from at least the shielding mechanism 80 of the electro-optic module 41.

[0139]

[0154] Alternatively, the tube 88 may be in electrical contact with the peripheral electro-optical plates of the stack 55, for example, the plate 60 furthest upstream or top of the stack 55. In one embodiment, the tube 88 includes at least a portion of the tube that is in contact with the peripheral electro-optical plates 60 of the stack 55, such as the plate 60 furthest upstream of the stack 55.

[0140]

[0155] Whether or not the tube 88 is connected to the electro-optic plate 60, at least a portion of the tube 88 can be set to a certain potential. The tube 88 can be set to a potential that is the same as or similar to the potential applied to the peripheral electro-optic plate 60 of the stack 55.

[0141]

[0156] As shown in Figure 12, in one embodiment, the tube 88 extends through a beam aperture 74 defined within one of the beam upstream electrostatic shield 71 and the beam downstream electrostatic shield 72. Specifically, in the configuration shown in Figure 12, the tube 88 extends through an aperture 74 defined within the beam upstream electrostatic shield 71. In one embodiment, the aperture 74 is located toward the central region of a dimension that crosses the dimension of the beam path. For example, the aperture 74 may be within a shielding mechanism 80 between opposite sides. The opposite sides may be equidistant from the aperture 74. In one embodiment, the electro-optical device 40 comprises individual tubes 88 configured to extend through the beam upstream electrostatic shield 71, and another individual tube configured to extend through the beam downstream electrostatic shield 72.

[0142]

[0157] Figure 13 is a schematic diagram showing a different view of the electro-optic module 41 shown in Figure 10. As shown in Figure 13, in one embodiment, the shielding mechanism 80 includes at least one side shield 81. The at least one side shield 81 is positioned on the side of the electro-optic plate 60 in a plane direction across the beam path. In one embodiment, the side shield 81 is configured to contribute to the confinement of the electrostatic field within the electro-optic module 41. In one embodiment, the side shield 81 is configured to prevent electrical breakdown between the electro-optic module 41 and external components of the electro-optic module 41. In one embodiment, the side shield 81 is configured to prevent electrical breakdown between the electro-optic module 41 and components on the side of the electro-optic module 41. In one embodiment, the side shield 81 is a side electrostatic shield.

[0143]

[0158] As shown in Figure 13, in one embodiment, the shielding mechanism 80 is formed by a beam upstream electrostatic shield 71 and a beam downstream electrostatic shield 72, in addition to side shields 81 on both sides of the stack 55. As shown in Figure 13, in one embodiment, at least one side shield 81 is connected to both the beam upstream insulator 76 and the beam downstream insulator 77.

[0144]

[0159] In one embodiment, the side shields 81 are electrically connected to each other and / or to the upstream beam electrostatic shield 71 and the downstream beam electrostatic shield 72. For example, the electrical connection may be provided by one or more conductive fasteners such as conductive adhesive, conductive clamps, and screws. It is not essential that the side shields 81 are electrically connected to each other or to the upstream beam electrostatic shield 71 or the downstream beam electrostatic shield 72. Small gaps may exist between one of the side shields 81 and adjacent ones among the upstream beam electrostatic shield 71 and the downstream beam electrostatic shield 72. In an alternative embodiment, the side shields 81 are independently connected to each other and to a voltage source that applies the same or the same potential to the side shields 81 as that applied to the upstream beam electrostatic shield 71 and the downstream beam electrostatic shield 72. The shielding mechanism 80 is configured to confine the electric field within the stack 55.

[0145]

[0160] As shown in Figure 13, in one embodiment, at least one side shield 81 extends upstream of the beam beyond one or more electro-optical plates 60. In one embodiment, at least one side shield 81 extends downstream of the beam beyond one or more electro-optical plates 60. The side shields 81 are configured to reduce the possibility of electrical breakdown between the stack 55 and components on the sides of the stack and external to the electro-optical module 41.

[0146]

[0161] In one embodiment, at least one side shield 81 (or at least a portion of such a side shield) includes a conduit for the flow of a thermal conditioning fluid. The thermal conditioning fluid is for thermally regulating the electro-optical module 41. Additionally or alternatively, one or more of the side shields 81 include a conductor, such as a metal body or metal block. The metal body may include its respective conduit. The side shields 81 may be provided as conductive blocks on both sides of the stack 55. The metal block may have a thermal conditioning function, thereby allowing the metal block to function as a cooling channel.

[0147]

[0162] Figure 14 is a schematic cross-section showing the electro-optic module 41 shown in Figures 13 and 10. In Figure 14, the cross-section shows the electrical cable 85 passing through it. As shown in Figures 13 and 14, in one embodiment, a side insulator 78 is provided on the inward surface of the side shield 81. As shown in Figure 13, in one embodiment, the side insulator 78 is configured to reduce the possibility of electrical breakdown between the side shield 81 and the electro-optic plate 60 of the stack 55. In one embodiment, the side insulator 78 is configured to reduce the possibility of voids or gaps on the inward surface of the side shield 81. By reducing the occurrence of voids or gaps, the increase in local electric field can be reduced, thereby reducing the possibility of undesirable electrical breakdown.

[0148]

[0163] As shown in Figure 13, in one embodiment, a filler material such as potting material can substantially fill the volume between the side shield 81 and the stack 55.

[0149]

[0164] As shown in Figure 14, in one embodiment, the side insulator 78 is configured to cover the inward surface of the side shield 81. In one embodiment, a gap is provided between the side insulator 78 and the electrical cable 85. Since the outward surface of the electrical cable 85 is electrically insulating and the inward surface of the side insulator 78 is electrically insulating, this does not excessively increase the risk of undesirable electrical breakdown.

[0150]

[0165] As described above, in one embodiment, for example, a portion of the electrical cable 85 adjacent to the stack 55 may not be shielded, and for example, the conductive elements of the cable may be bare (i.e., bare portion), i.e., without an insulating cover or surface. The bare portion may allow for effective electrical connection of the electrical cable 85 to the stack's connectors for connecting one or more plates 60. It should be noted that the bare portion is shielded by the shielding mechanism 80. In order for the shielding mechanism to effectively shield the bare portion of the cable 85, the distal end of the bare portion of the cable away from the stack 55 is sufficiently retracted into the shielding mechanism 80 to suppress, if not prevent, undesirable discharge from the bare portion, and otherwise suppress electrical breakdown. That is, elements of the shielding mechanism 80, such as the beam upstream electrostatic shield 71, the beam downstream electrostatic shield 72, and the side shield 81, may protrude far from the stack (e.g., the beam path) and at a sufficient distance from the distal end of the bare portion to suppress, if not prevent, discharge. In one embodiment, for example, the bare portion of the electrical cable 85 may be positively charged relative to the shielding mechanism 80. Alternatively, the shielding mechanism 80 may be considered negatively charged relative to the electrical cable 85. The possibility of undesirable discharge toward the electrical cable 85 is reduced by having all surfaces facing the electrical cable 85 made from an electrical insulator and by having the elements of the shielding mechanism 80 extend outward from the stack surrounding the end of the electrical cable 85. As shown in Figure 14, in one embodiment, the surfaces facing the cable 85 are made from an insulator by providing an upstream beam insulator 76, a downstream beam insulator 77, and a side insulator 78.

[0151]

[0166] As shown in Figure 12, in one embodiment, a tube 88 is provided that passes through the aperture 74. Figure 15 is a schematic diagram showing how such a tube 88 extends through the aperture 74 on the beam upstream side of the electron-optic module 41. In one embodiment, the electron-optic plate 60 furthest upstream of the beam (i.e., the beam upstream plate 64 shown in Figure 15) may be positively charged with respect to the shielding mechanism 80. Alternatively, the shielding mechanism 80 may be considered negatively charged with respect to the beam upstream plate 64. In one embodiment, the tube 88 may be positively charged with respect to the shielding mechanism 80 (or the shielding mechanism 80 may be considered negatively charged with respect to the tube 88).

[0152]

[0167] Figure 16 is a schematic diagram of a modified version of the electro-optic module 41 shown in Figure 15. As shown in Figure 16, in one embodiment, the electro-optic module 41 includes an insulating cover 79. The insulating cover may be an insulating layer, such as an insulating coating of insulating material. The insulating cover 79 is configured to cover the radially inward circumferential surface 73 of the electrostatic shield 71. The insulating cover 79 may be annular, planar, or ring-shaped. For example, the insulating cover 79 may be configured to define the limits of the coating on one or both of the beam upstream electrostatic shield 71 and the beam downstream electrostatic shield 72. As shown in Figure 16, in one embodiment, the insulating cover 79 is configured to cover the edges of the coating on each of the beam upstream electrostatic shield 71 and the beam downstream electrostatic shield 72. In one embodiment, the insulating cover 79 is configured to define the limits of the coating.

[0153]

[0168] One embodiment of the present invention is expected to reduce the possibility of electrical dielectric breakdown between the shielding mechanism and either the tube 88 or the beam upstream plate 64. An increase in the electric field may occur at the edge of the coating facing the tube 88 or the beam upstream plate 64. Such an increase in the electric field may result in the emission of electrons and subsequent discharge toward the tube 88 or the beam upstream plate 64. By providing the insulating cover 79, such an increase in the electric field is reduced, if not prevented.

[0154]

[0169] As shown in Figure 16, in one embodiment, the insulating cover 79 encloses the coating edges facing the tube 88 and the beam upstream plate 64. Otherwise, localized increases in electric fields that may occur within or on the insulator can be reduced or prevented.

[0155]

[0170] A triple point 89 can be defined where an electrical conductor, an electrical insulator, and the environment meet. Such a triple point is shown in Figure 16 as being defined where the coating forming the beam-upstream electrostatic shield 71 meets the insulating cover 79 and gases in the environment. This triple point is located where the electric field is low. Positioning the triple point away from sharp edges compared to a configuration without the insulating cover 79 relatively reduces the electric field. Therefore, the risk of electrical breakdown to such a triple point from further elements is expected to be reduced or eliminated. On the other hand, a triple point is not provided in a region of higher electric fields, i.e., in the region between the shielding mechanism 80 and the liner tube 88 or the beam-upstream plate 64 of the stack 55. That is, the use of the insulating cover 79 moves the triple point from between the vacuum, the coating of the electrostatic shield 71, and the insulator 76 to a location on the upper electrostatic shield 71 with a lower discharge risk.

[0156]

[0171] In one embodiment, the tube 88 has a rounded edge. By providing a rounded edge, the increase in the electric field caused by a sharp edge can be reduced or prevented. This can reduce the possibility of electrical dielectric breakdown from the tube 88 toward the shielding mechanism 80. This may be desirable when the tube 88 is negatively charged relative to the shielding mechanism 80.

[0157]

[0172] As shown in Figure 12, in one embodiment, the electrical connector 84 is provided on two different sides of the stack 55. In an alternative embodiment, the electrical connector 84 is provided on only one side of the stack 55. Such a configuration of the stack 55 may have a single cooling conduit extending around more than one side of the electro-optical module, for example, two or three sides of module 41. In an alternative embodiment, the electrical connector 84 is provided on more than two sides of the stack 55. For example, in one embodiment, the stack 55 may be, for example, triangular, square, pentagonal, hexagonal, or circular when viewed from a direction along the beam path. The cooling conduit may extend along two or more adjacent sides of such a shaped stack 55. An electrical connection to the electrical connector 84 may be provided on any or all of the sides of the stack 55. In one embodiment, a side shield 81 is provided on each side of the stack 55 that does not need to provide the electrical connector 84. For example, in one embodiment, the stack 55 is square or rectangular (i.e., has four sides) when viewed from a direction along the beam path. In one embodiment, all of the electrical connectors 84 are provided on the same side of the stack 55. Side shields 81 may be provided on three other sides of the stack 55. In one configuration, a side of the stack that does not have side shields 81 at least partially may define an opening for the electrical connectors 81, together with other elements of the shielding mechanism, such as the beam upstream electrostatic shield 71 and the beam downstream electrostatic shield 72. Such an opening (or access opening) may provide access for electrical cables 85 to the electrical connectors 84. The access opening may provide access through the side of the shielding mechanism. Access for the cables 85 to the connectors 84 may be through a gap (or volume), i.e., the gap (or volume) between the beam upstream electrostatic shield 71 and the beam downstream electrostatic shield 72. The access opening may be defined outside the shielding mechanism between the beam upstream electrostatic shield 71, the beam downstream electrostatic shield 72, and the side shield 81 adjacent to the side of the stack 55 having the access opening.The gap may be defined within the shielding mechanism in the beam upstream electrostatic shield 71, the beam downstream electrostatic shield 72, and the side shield 81 that define the access opening.

[0158]

[0173] In one embodiment, the electro-optical module 41 shown in Figures 10 to 16 may correspond to the beam downstream module 41c shown in Figure 7. The beam downstream module 41c may include, for example, a control lens array 250, an objective lens array 241, and a detector 240. In an alternative embodiment, the electro-optical module 41 may correspond to the beam upstream module 41a or intermediate module 41b shown in Figure 7. In one embodiment, sections of the tube 88 may be provided at both the beam upstream and beam downstream ends of the electro-optical module 41. For example, the beam upstream section of the tube 88a may extend through an opening 74 at the beam upstream end of the beam upstream module 41a, and the intermediate section 88b of the tube may extend through an opening 74 at the beam downstream end of the beam upstream module 41a. In one embodiment, the intermediate tube section 88b extends through an opening 74 at the beam upstream end of the intermediate module 41b. The beam downstream tube section 88c may extend through an opening 74 at the beam downstream end of the intermediate module 41b.

[0159]

[0174] As shown in Figure 16, an insulating cover 79 may be provided at the beam upstream end of the electro-optic module 41. In one embodiment, the insulating cover 79 may be provided at both the beam upstream and beam downstream ends of the electro-optic module 41. The insulating cover 79 may be provided around an opening in the electrostatic shield 71 of the shielding mechanism 80. The opening may be for the insertion of the end of a tube 88 through the electrostatic shield 71.

[0160]

[0175] As described above, in one embodiment, a tube 88 may be provided at the beam-downstream end of the electron-optic module 41. In one embodiment, the tube 88 is at substantially the same potential as the electron-optic plate 60 furthest downstream of the beam in the stack. Alternatively, a potential difference may be applied between the tube 88 and the electron-optic plate 60 furthest downstream of the beam in the stack to form an electrostatic field for acting on the electron beam. Such a potential difference can be used to focus the electron beam.

[0161]

[0176] In one embodiment, one or more sections of the shielding mechanism 80 are connected to ground potential. For example, the shielding mechanism 80 may be connected to the vacuum chamber 10 of the evaluation device 100.

[0162]

[0177] In one embodiment, the electron beam is a beam grid of multiple electron beams. That is, references to electron beams in the preceding description, such as those shown and described with reference to Figures 8 to 16, include references to multiple electron beams, for example, as such a beam grid in the form of an array of beams. At least one path of the beams in the beam grid may correspond to a path electron beam, such as the central beam of the beam grid or a beam towards the center of the array, as described with reference to Figures 8 to 16. The electron-optical plates of stack 55 may include a series of electron-optical plates containing multiple apertures for the paths of the multiple electron beams of the beam grid.

[0163]

[0178] In one embodiment, a method for guiding an electron beam is provided. This method is for guiding an electron beam along a beam path toward a sample location.

[0164]

[0179] In one embodiment, the method involves acting on an electron beam with one or more electron-optical plates 60 of a stack 55. In one embodiment, one or more electron-optical plates 60 are arranged across the beam path.

[0165]

[0180] In one embodiment, the method includes using a shielding mechanism 80. The shielding mechanism 80 includes an upstream electrostatic shield 71 positioned across the beam path upstream of one or more electron-optical plates 60. The shielding mechanism 80 includes a downstream electrostatic shield 72 positioned across the beam path downstream of one or more electron-optical plates 60. The shielding mechanism 80 is used to prevent electrical breakdown between the stack 55 and external components of the stack 55. In one embodiment, the shielding mechanism 80 is used to confine an electrostatic field within the shielding mechanism 80. Such an electrostatic field may be generated, for example, when one or more electron-optical plates act on the electron beam along the beam path.

[0166]

[0181] The electron-optical module 41 comprises, or may comprise, a lens assembly for acting upon (or manipulating) electron beamlets. The lens assembly may be, for example, an objective lens assembly or a focusing lens assembly, or a part thereof. A lens assembly such as an objective lens assembly may further comprise an additional lens array including at least two plates, such as a control lens array 250.

[0167]

[0182] In one embodiment, at least one of the electro-optical plates 60 includes a micro-electromechanical component. In one embodiment, the electro-optical module 41 comprises one or more electro-optical elements that may be called micro-electromechanical components (even though such components do not have to include motion or movable features), or some of which may be fabricated using techniques suitable for fabricating micro-electromechanical components designed to have electro-optical functionality (e.g., “MEMS techniques”). The electro-optical module 41, or at least the components of the electro-optical module 41, may be fabricated by such techniques. The electro-optical module 41 may comprise one or more elements that may be considered MEMS elements. One or more such elements may be controlled to be set to a high potential difference with respect to a reference potential (e.g., ground) during use. Such elements may be electrically connected to one or more voltage sources for supplying voltage to the elements. In one embodiment, a controller is configured to control the voltage applied to the elements. Such elements may require precise positioning (e.g., alignment) within the electro-optic module 41 with respect to the beam grid path, and to other electro-optic elements in the device, for example, to the source, and to the sample and / or beam grid path. One embodiment of the present invention is expected to enable more precise positioning (e.g., alignment) of such elements within a stack 55 of such electro-optic modules 41, for example, during operation, without distortion of the electro-optic module 41 due to externally applied forces or moments. In addition, or alternatively, one embodiment of the present invention may enable more precise positioning, e.g., alignment of such elements with respect to other elements in the electro-optic device 40, and therefore of the stack 55 of electro-optic modules containing such elements within the electro-optic device 40.

[0168]

[0183] As described above, in one embodiment, the electro-optical module 41 is an electro-optical lens assembly. The electro-optical lens assembly may include an objective lens assembly. The electro-optical lens assembly can be an objective lens assembly. In an alternative embodiment, the electro-optical lens assembly is an electro-optical focusing lens assembly.

[0169]

[0184] In one embodiment, the electro-optic module 41 includes a collimator. For example, in one embodiment, the electro-optic module 41 includes a magnetic collimator in combination with an electrostatic focusing lens array. The electro-optic module 41 may include a single aperture lens array having one or two macroelectrodes, positioned away from the virtual light source conjugate plane.

[0170]

[0185] In an alternative embodiment, the electro-optical module 41 comprises a magnetic macrolens in combination with an electrostatic slit deflector. The magnetic macrolens may be for collimation. As a further alternative, in one embodiment, the electro-optical module 41 comprises a combined magnetic and electrostatic macrolens and a beam downstream slit deflector.

[0171]

[0186] Generally, the electro-optical module 41 may comprise a plate for a detector array, a plate for lens electrodes (in which multiple deflectors may be integrated), multiple deflector arrays, a beam aperture array (e.g., an upper beam aperture array and / or a final beam limiting array), a deflector array (e.g., a strip deflector array), and any other plates such as other types of correction elements.

[0172]

[0187] The embodiments described herein primarily focus on multi-beam electron-optical devices 40. The present invention is equally applicable to single-beam electron-optical devices 40.

[0173]

[0188] Multiple electron-optical devices may be included in the electron-optical device array. Preferably, the electron-optical devices in the electron-optical device array are configured to simultaneously focus each multibeam onto different regions of the same sample.

[0174]

[0189] References to the upper and lower sides, up and down, upward and downward, upper and lower parts, etc., should be understood to refer to directions parallel to the (not always, but typically vertical) beam upstream (i.e., forming the electron source) and beam downstream (i.e., toward the sample) directions of the charged particle beam impacting Sample 208. Thus, references to the beam upstream and beam downstream are intended to refer to directions relative to the beam path, independently of any current gravitational field. References to the beam path refer to the intended position of the corresponding beam during the operation of the charged particle apparatus. In this context, for example, beam upstream may be considered to relate to terms such as upper, up, upward, and upper, and beam downstream may be considered to relate to lower, down, downward, and lower. When such references are made in relation to electron-optical elements such as electrode plates, they can generally be understood to relate to the optical axis of the beam and therefore perpendicular to the plane of the electron-optical element, for collimated beam paths of a beam grid. For uncollimated beams, such as divergent beams, the beam path can be considered to be relative to the axis of the beam's midpoint, or, if the beam is one of multiple beams within a beam grid, to the axis of the midpoint of the beam grid. Therefore, the direction of the beam path can be considered to be an axis perpendicular to the plane of the planar electron-optic element, but this is not always the case, and depending on the embodiment, the beam path may form an angle (for example, obliquely) with respect to such a planar electron-optic element.

[0175]

[0190] While the present invention has been described in relation to various embodiments, other embodiments of the present invention will become apparent to those skilled in the art from the discussion herein and the practices of the present invention disclosed herein. For example, as described above, in one embodiment the substrate has portions of varying thickness, and the electrical connector extends through the thinner portion. Alternatively, however, the thickness of the substrate may be uniform. The electrical connections for electronic components may be located further periphery of the substrate than the electronic components, and the conductive layer may be electrically connected to the electrical connections. This specification and examples are to be considered merely illustrative, and the true scope and spirit of the present invention are intended to be shown by the following claims.

[0176]

[0191] The above description is intended to be illustrative, not limiting. Therefore, it will be apparent to those skilled in the art that modifications can be made as described without departing from the claims and provisions described below.

[0177]

[0192] While the present invention has been described in relation to various embodiments, other embodiments of the invention will become apparent to those skilled in the art from the discussion herein and the practice of the invention disclosed herein. This specification and examples are intended to be illustrative only, and the true scope and spirit of the invention are set forth by the following claims and clauses.

[0178]

[0193] The following terms and conditions are provided.

[0194] Clause 1. A charged particle optical module for a charged particle optical device configured to guide a charged particle beam toward a sample position along a beam path, comprising: a stack including one or more charged particle optical plates positioned across the beam path and configured to act on the charged particle beam; and a shielding mechanism including an upstream electrostatic shield positioned across the beam path upstream of one or more charged particle optical plates, and a downstream electrostatic shield positioned across the beam path downstream of one or more charged particle optical plates, wherein the shielding mechanism is configured to prevent electrical breakdown between the charged particle optical module and external components of the charged particle optical module and / or to confine an electrostatic field within the charged particle optical module, the electrostatic field being generated, for example, when one or more charged particle optical plates act on a charged particle beam along a beam path.

[0195] Clause 2. The charged particle optical module according to Clause 1, wherein the shielding mechanism is configured to extend across the beam path beyond one or more charged particle optical plates, preferably a beam upstream electrostatic shield and a beam downstream electrostatic shield extending across the beam path beyond one or more charged particle optical plates.

[0196] Clause 3. A charged particle optical module according to Clause 1 or 2, comprising at least one electrical connector for connecting at least one of the charged particle optical plates to a voltage source.

[0197] Clause 4. The charged particle optical module as described in Clause 3, wherein the shielding mechanism extends in a direction across the beam path to prevent electrical breakdown between the electrical connector and the external components of the charged particle optical module.

[0198] Clause 5. A charged particle optical module for a charged particle optical device configured to guide a charged particle beam toward a sample position along a beam path, the charged particle optical module comprising: a stack comprising one or more charged particle optical plates positioned across the beam path and configured to act on the charged particle beam; at least one electrical connector configured to connect at least one of the charged particle optical plates to a voltage source; and preferably a shielding mechanism configured to extend across the beam path upstream and downstream of the stack and protrude beyond the connectors to shield external components of the module from discharge with at least one connector and / or an electrostatic field generated within the module, preferably the shielding mechanism comprising an upstream electrostatic shield positioned across the beam path upstream of the beam and extending across the beam path upstream of the stack, and a downstream electrostatic plate configured to extend across the beam path upstream of the stack.

[0199] Clause 6. A charged particle optics module as described in any one of Clauses 3 to 5, wherein the electrical connector is located between the beam upstream electrostatic shield and the beam downstream electrostatic shield.

[0200] Clause 7. A charged particle optics module as described in any one of Clauses 1 to 6, wherein the beam upstream electrostatic shield and the beam downstream electrostatic shield are configured to have a common potential and / or are electrically connected to each other.

[0201] Clause 8. A charged particle optical module according to any one of Clauses 1 to 7, wherein the shielding mechanism includes at least one side shield positioned on the side of the charged particle optical plate in a plane direction across the beam path, the side shield being configured to contribute to the confinement of an electrostatic field into the charged particle optical module and / or to prevent electrical breakdown between the charged particle optical module and external components of the charged particle optical module, for example, on the side of the charged particle optical module, preferably the side shield being a side electrostatic shield. An electrical connector is positioned between the beam upstream electrostatic shield, the beam downstream electrostatic shield, and at least one side shield. The beam upstream electrostatic shield, the beam downstream electrostatic shield, and at least one side shield (optionally, at least two side shields) define an opening (or access opening) within the shielding mechanism. The opening is configured to provide access to the electrical connector, for example, by an electrical cable. The beam upstream electrostatic shield, the beam downstream electrostatic shield, and at least one side shield (optionally, at least two side shields) define a gap within the shielding mechanism configured for the passage of an electrical cable, for example, to reach a connector.

[0202] Clause 9. A charged particle optical module as described in Clause 8, wherein at least one side shield extends upstream of the beam beyond one or more charged particle optical plates and / or downstream of the beam beyond one or more charged particle optical plates.

[0203] Clause 10. A charged particle optical module according to Clause 8 or 9, wherein at least one side shield is electrically connected to the beam upstream electrostatic shield and / or beam downstream electrostatic shield, preferably, each side shield is connected to the beam upstream and / or beam downstream electrostatic shield, and / or one or more of the at least one side shield is configured to have the same potential as one or both of the beam upstream electrostatic shield and / or beam downstream electrostatic shield.

[0204] Clause 11. A charged particle optical module according to any one of Clauses 8 to 10, wherein at least one side shield includes a conduit for the flow of a thermally regulated fluid for thermally regulating the charged particle optical module, and / or one or more of the at least one side shields include a metal body, preferably the metal body includes the respective conduit.

[0205] Clause 12. Preferably, a charged particle optical module according to any one of Clauses 1 to 11, comprising a shielding mechanism, e.g., an insulator disposed on at least one inward-facing surface of a beam upstream electrostatic shield, a beam downstream electrostatic shield, and / or another side shield, to prevent electrical breakdown between the shielding mechanism and another part of the charged particle optical module.

[0206] Clause 13. The charged particle optical module according to Clause 12, wherein at least part of the shielding mechanism includes a conductive coating on an insulator, for example, at least one of at least one of a beam downstream electrostatic shield, a beam upstream electrostatic shield, and a side shield includes a conductive coating on an insulator, preferably the insulator includes a filler material such as a potting material.

[0207] Clause 14. A charged particle optical module according to Clause 12 or 13, wherein a filler material, such as a potting material, is provided between at least a portion of another surface of the shielding mechanism, such as at least one of the beam upstream electrostatic shield, beam downstream electrostatic shield, and at least one side shield, and the insulator, in order to substantially avoid a gap between the electrostatic shield and the insulator.

[0208] Clause 15. A charged particle optical module according to any one of Clauses 12 to 14, wherein a filler material, such as a potting material, is included between at least a portion of another surface of the shielding mechanism and the stack in order to substantially avoid a gap between the shielding mechanism and the insulator.

[0209] Clause 16. A charged particle optical module according to any one of Clauses 1 to 15, wherein at least an aperture is defined within the shielding mechanism, preferably at least one of the beam upstream electrostatic shield and beam downstream electrostatic shield includes an aperture for the beam path, preferably the aperture is defined within a radially inward circumferential surface, and preferably the aperture is centered within the charged particle optical module with respect to the stack, for example.

[0210] Clause 17. A charged particle optics module according to Clause 16, comprising an insulating cover configured to cover the radially inward circumferential surface of an electrostatic shield, for example, the insulating cover configured to define the limits of a coating on one or both of the beam upstream electrostatic shield and the beam downstream electrostatic shield, preferably the insulating cover configured to cover the edges of the coating on each of the beam upstream electrostatic shield and the beam downstream electrostatic shield in order to define the limits of the coating.

[0211] Clause 18. A charged particle optical module according to any one of Clauses 1 to 17, wherein the shielding mechanism comprises one or more charged particle optical plates of the stack, preferably at least one of the beam upstream electrostatic shield and beam downstream electrostatic shield comprises at least one charged particle optical plate.

[0212] Clause 19. A charged particle optical module as described in any one of Clauses 1 to 18, wherein the stack preferably includes at least one spacer configured to support and / or electrically isolate at least one of the charged particle optical plates, for example, the individual spacers being positioned between pairs of charged particle optical plates, and for example, the shielding mechanism includes at least one spacer, preferably the spacers being included in the beam upstream electrostatic shield and the beam downstream electrostatic shield, respectively.

[0213] Clause 20. The charged particle optical module according to Clause 19, wherein at least one of the spacers is a radial spacer positioned around one of the charged particle optical plates, preferably so that the charged particle optical plate is positioned between the beam path and the radial spacer, preferably the radial spacer is configured to separate the charged article optical plate from another component of the charged particle optical module in the direction along the beam path, the other component preferably another charged particle optical plate.

[0214] Clause 21. A charged particle optical module according to any one of Clauses 1 to 20, wherein at least one of the charged particle optical plates includes a detector positioned across the beam path, preferably the detector is configured to detect charged particles from the sample position, and the detector preferably includes a detector array of detector elements.

[0215] Clause 22. A charged particle optical module according to any one of Clauses 1 to 21, further comprising a tubular portion configured to surround a portion of a beam path, preferably the tubular portion being in contact with a charged particle optical plate, preferably the tubular portion being configured to protrude through an opening defined within a shielding mechanism, for example, the opening being defined within one of an upstream beam electrostatic shield and a downstream beam electrostatic shield, preferably the tubular portion being positioned away from the surface of the opening.

[0216] Clause 23. A charged particle optics module as described in any one of Clauses 1 to 22, wherein the charged particle beam is a beam grid of multiple charged particle beams, and the charged particle optics plate of the stack each includes multiple apertures for the paths of the multiple charged particle beams of the beam grid.

[0217] Clause 24. A charged particle optical device configured to guide a charged particle beam along a beam path toward a sample position, wherein the charged particle optical device comprises a charged particle optical module as described in any one of Clauses 1 to 23.

[0218] Clause 25. A charged particle optics device configured to guide a charged particle beam along a beam path toward a sample position, comprising: a conductive tube configured to surround a beam path; and a charged particle optics module, wherein the charged particle optics module comprises: a stack including one or more charged particle optics plates positioned across the beam path and configured to act on the charged particle beam; and a shielding mechanism configured to shield the stack and to extend upstream of the stack in a direction across the beam path and downstream of the stack in a direction across the beam path, wherein the shielding mechanism is connected to the conductive tube A charged particle optical device further comprising another component which extends further from the beam path than the stack, preferably the module further comprises a connector for another of the charged particle plates, the shielding mechanism further extends further from the beam path than the connector, preferably configured to be set to a low potential, preferably to ground, and configured adjacent to the surface of the shielding mechanism such as the beam upstream shield, preferably the other component having a surface corresponding to at least a portion of the beam upstream shield, for example, the surface of the other component is configured to be parallel to and facing at least a portion of the surface of the beam upstream shield.

[0219] Clause 26. A charged particle optical device according to Clause 25, comprising at least one conductive tube around a beam path, wherein the separated tube is from a charged particle optical module, preferably at least from a shielding mechanism of the charged particle optical module, the conductive tube is in electrical contact with a peripheral charged particle optical plate of the stack, the tube preferably includes at least a portion of the tube in contact with the peripheral charged particle optical plate of the stack, and / or at least a portion of the tube is preferably set to the same potential as the peripheral charged particle optical plate.

[0220] Clause 27. The charged particle optical device according to Clause 26, wherein the tubes extend through a beam aperture defined within one of an upstream beam electrostatic shield and a downstream beam electrostatic shield, and the beam aperture is preferably located within the shield in the central region of a dimension transverse to the direction of the beam path, for example between opposite sides, for example equidistant from two further sides, and preferably the charged particle optical device comprises individual tubes configured to extend through an upstream beam electrostatic shield and a downstream beam electrostatic shield, respectively.

[0221] Clause 28. A charged particle optical device as described in any one of Clauses 25 to 27, comprising a removable module for removable placement within the device.

[0222] Clause 29. A charged particle optical apparatus comprising a charged particle optical module as described in any one of Clauses 1 to 24 or a charged particle optical device as described in any one of Clauses 25 to 28.

[0223] Clause 30. The charged particle optical apparatus according to Clause 29, comprising a voltage source configured to supply potential to at least one of the charged particle optical plates.

[0224] Clause 31. The charged particle optical apparatus according to Clause 30, wherein the voltage source is configured to supply a potential such that the potential difference between at least one of the charged particle optical plates and the shielding mechanism is at least 1 kV, optionally at least 2 kV, optionally at least 5 kV, optionally at least 10 kV, optionally at least 20 kV, and optionally at least 30 kV, optionally in the range of 1 kV to 40 kV.

[0225] Clause 32. A charged particle optical apparatus as described in any one of Clauses 29 to 31, comprising an operable stage for supporting a sample at the sample position.

[0226] Article 33. A method for guiding a charged particle beam along a beam path toward a sample location, wherein the method is The act of acting on a charged particle beam with one or more charged particle optical plates in a stack, wherein the one or more charged particle optical plates are positioned across the beam path. A shielding mechanism is used to prevent electrical breakdown between the stack and external components of the stack, and / or, for example, to confine the electrostatic field generated when one or more charged particle optical plates act on the charged particle beam along the beam path within the shielding mechanism, including an upstream electrostatic shield positioned upstream of one or more charged particle optical plates across the beam path, and a downstream electrostatic shield positioned downstream of one or more charged particle optical plates across the beam path. Methods that include...

Claims

1. A charged particle optics module for a charged particle optics device configured to guide a charged particle beam along a beam path toward a sample position, wherein the charged particle optics module is A stack comprising one or more charged particle optical plates positioned across the beam path and configured to act on the charged particle beam, A shielding mechanism comprising: an upstream electrostatic shield positioned upstream of the beam of one or more charged particle optical plates across the beam path; a downstream electrostatic shield positioned downstream of the beam of one or more charged particle optical plates across the beam path; and at least one side shield positioned on the side of the charged particle optical plate in a plane direction across the beam path. Equipped with, The shielding mechanism is configured to prevent electrical dielectric breakdown between the charged particle optical module and external components of the charged particle optical module, and / or to confine an electrostatic field within the charged particle optical module, wherein the electrostatic field is generated, for example, when one or more charged particle optical plates act on the charged particle beam along the beam path of the charged particle optical module.

2. The charged particle optical module according to claim 1, wherein the shielding mechanism is configured to extend beyond one or more charged particle optical plates in a direction that crosses the beam path, preferably the beam upstream electrostatic shield and the beam downstream electrostatic shield extend beyond one or more charged particle optical plates in a direction that crosses the beam path.

3. The charged particle optical module according to claim 1 or 2, further comprising at least one electrical connector for connecting at least one of the charged particle optical plates to a voltage source.

4. The charged particle optical module according to claim 3, wherein the shielding mechanism extends in a direction across the beam path to prevent electrical dielectric breakdown between the electrical connector and external components of the charged particle optical module.

5. The charged particle optical module according to claim 3 or 4, wherein the electrical connector is located between the beam upstream electrostatic shield and the beam downstream electrostatic shield.

6. The charged particle optical module according to any one of claims 1 to 5, wherein the upstream electrostatic shield and the downstream electrostatic shield are configured to have a common potential and / or are electrically connected to each other.

7. The charged particle optical module according to any one of claims 1 to 6, wherein the side shield is configured to contribute to the confinement of the electrostatic field within the charged particle optical module and / or to prevent electrical dielectric breakdown between the charged particle optical module and external components of the charged particle optical module, for example, the side of the charged particle optical module, and preferably the side shield is a side electrostatic shield.

8. The charged particle optical module according to claim 7, wherein the at least one side shield extends upstream of the beam beyond the one or more charged particle optical plates and / or downstream of the beam beyond the one or more charged particle optical plates.

9. The charged particle optical module according to claim 7 or 8, wherein at least one side shield is electrically connected to the beam upstream electrostatic shield and / or the beam downstream electrostatic shield, preferably each side shield is connected to the beam upstream and / or beam downstream electrostatic shield, and / or one or more of the at least one side shield is configured to have the same potential as one or both of the beam upstream electrostatic shield and / or the beam downstream electrostatic shield.

10. Preferably, the charged particle optical module according to any one of claims 1 to 9, further comprising an insulator disposed on at least one inward-facing surface of the shielding mechanism, for example, the beam upstream electrostatic shield, the beam downstream electrostatic shield, and / or another side shield, to prevent electrical dielectric breakdown between the shielding mechanism and another part of the charged particle optical module.

11. The charged particle optical module according to claim 10, wherein at least a portion of the shielding mechanism includes a conductive coating on an insulator, for example, at least one of the downstream beam electrostatic shield, the upstream beam electrostatic shield, and the side shield includes the conductive coating on the insulator, preferably the insulator includes a filler material such as a potting material.

12. A charged particle optical module according to any one of claims 1 to 11, wherein at least an aperture is defined within the shielding mechanism, preferably at least one of the beam upstream electrostatic shield and the beam downstream electrostatic shield includes an aperture for the beam path, preferably the aperture is defined within a radially inward circumferential surface, and preferably the aperture is centered within the charged particle optical module with respect to the stack, for example.

13. The charged particle optical module according to any one of claims 1 to 12, wherein the shielding mechanism includes one or more of the charged particle optical plates of the stack, preferably at least one of the beam upstream electrostatic shield and the beam downstream electrostatic shield includes at least one of the charged particle optical plates.

14. The charged particle optical module according to any one of claims 1 to 13, further comprising a tubular portion configured to surround the portion of the beam path, preferably the tubular portion being in contact with a charged particle optical plate, preferably the tubular portion being configured to protrude through an opening defined within the shielding mechanism, for example, the opening being defined within one of the beam upstream electrostatic shield and the beam downstream electrostatic shield, preferably the tubular portion being positioned away from the surface of the opening.

15. A charged particle optical module according to any one of claims 1 to 14, wherein the charged particle beam is a beam grid of a plurality of charged particle beams, and the charged particle optical plate of the stack each includes a plurality of apertures for the paths of the plurality of charged particle beams of the beam grid.

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