Electro-optical assembly with electromagnetic shielding

Abstract

It shields the charged particle beam from external electromagnetic fields. [Solution] An electro-optical assembly for an electro-optical column 40 for projecting a charged particle beam along a beam path toward a target, wherein the electro-optical assembly includes an electromagnetic shield 31 configured to surround the charged particle beam path and shield the charged particle beam from an electromagnetic field outside the electromagnetic shield 31, the electromagnetic shield 31 includes a plurality of sections 32 extending along different locations along the beam path, each section 32 surrounding the charged particle beam, and the sections 32 are separable.

Description

Technical Field

[0001] Cross - reference to related applications

[0001] This application claims the priority of U.S. Patent Application No. 63 / 075,289, filed on September 7, 2020, European Patent Application No. 20200740.7, filed on October 8, 2020, and U.S. Patent Application No. 63 / 126932, filed on December 17, 2020, which are hereby incorporated by reference in their entirety.

[0002]

[0002] The embodiments provided herein generally relate to the provision of electron - optical assemblies, modules, and electron - optical columns for use, for example, in charged - particle beam inspection apparatuses. Embodiments also provide methods for manufacturing an electron - optical assembly, methods for replacing a module, and methods for projecting a charged - particle beam along a beam path towards a target.

Background Art

[0003]

[0003] When manufacturing a semiconductor integrated circuit (IC) chip, for example, as a result of optical effects and incidental particles, unwanted pattern defects inevitably occur during the manufacturing process on a substrate (i.e., a wafer) or a mask, thereby reducing the yield. Therefore, monitoring the degree of unwanted pattern defects is an important process in the manufacture of IC chips. More generally, the 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 inspection tools using charged particle beams have been used to inspect objects, for example, to detect pattern defects. These tools generally use electron microscopy techniques such as scanning electron microscopes (SEMs). In an SEM, a primary electron beam of relatively high-energy electrons is targeted in a final deceleration step to land on the target with a relatively low landing energy. The electron beam is focused on the target as a probing spot. The interaction between the material structure at the probing spot and the landed electrons from the electron beam causes electrons such as secondary electrons, backscattered electrons, or Auger electrons to be emitted from the surface. The generated secondary electrons can be emitted from the material structure of the target. By scanning the primary electron beam as a probing spot across the target surface, secondary electrons can be emitted across the target surface. By collecting these emitted secondary electrons from the target surface, the pattern inspection tool can obtain an image representing the material structure features of the target surface.

[0005]

[0005] Another application of electron-optical columns is lithography. A charged particle beam reacts with a resist layer on the substrate surface. A desired pattern in the resist can be created by controlling the location on the resist layer where the charged particle beam is directed.

[0006]

[0006] The electron-optical column may also be a device for generating, illuminating, projecting, and / or detecting one or more charged particle beams. The charged particle beam path is controlled by an electromagnetic field. A stray electromagnetic field may undesirably deflect the beam.

[0007]

[0007] There is a general need to improve the control of charged particle beam paths. [Overview of the project]

[0008]

[0008] According to a first aspect of the present invention, an electron-optical assembly for an electron-optical column for projecting a charged particle beam along a beam path toward a target is provided, wherein the electron-optical assembly includes an electromagnetic shield configured to surround a charged particle beam path and shield the charged particle beam from an electromagnetic field outside the electromagnetic shield, the electromagnetic shield includes a plurality of sections extending along different locations along the beam path, each section surrounding a charged particle beam path, and the sections are separable.

[0009]

[0009] According to a second aspect of the present invention, a module is provided which includes an electro-optical device and an electromagnetic shield for a beam path through a module when it is located in an electro-optical column for projecting a charged particle beam along a beam path toward a target, wherein the electromagnetic shield includes an up-beam section of the up-beam of the electro-optical device and a down-beam section of the down-beam of the electro-optical device, and at least one of the up-beam section and the down-beam section has an interface that extends radially with respect to the beam path.

[0010]

[0010] According to a third aspect of the present invention, an electro-optical assembly is provided for an electro-optical column for projecting a charged particle beam along a beam path toward a target, wherein the electro-optical assembly includes an electromagnetic shield configured to surround a charged particle beam path and shield the charged particle beam from an electromagnetic field outside the electromagnetic shield, the electromagnetic shield includes a plurality of sections that extend along and surround the beam path, each section surrounding a charged particle beam path, and at least two of the sections include adjacent ends that are separable and electromagnetically engage with each other.

[0011]

[0011] According to a fourth aspect of the present invention, a method is provided for manufacturing an electro-optical assembly for an electro-optical column for projecting a charged particle beam along a beam path toward a target, the method comprising providing an electromagnetic shield to surround the charged particle beam and to shield the charged particle beam from an electromagnetic field outside the electromagnetic shield, wherein the electromagnetic shield comprises a plurality of sections extending along different locations along the beam path, each section surrounding the charged particle beam path, and the sections are separable.

[0012]

[0012] A fifth aspect of the present invention provides a method for replacing a module of an electron-optical column for projecting a charged particle beam along a beam path toward a target, the method comprising removing a module from an electron-optical column, the electron-optical column comprising an electromagnetic shield configured to surround a charged particle beam path and shield the charged particle beam from an electromagnetic field outside the electromagnetic shield, the electromagnetic shield comprising a plurality of sections extending along different locations along the beam path, each section surrounding a charged particle beam path, at least one of the sections being contained within a module and separable from other sections of the module's up-beam and / or down-beam sections.

[0013]

[0013] According to a sixth aspect of the present invention, a method is provided for projecting a charged particle beam along a beam path toward a target, the method comprising shielding the charged particle beam from an electromagnetic field outside an electromagnetic shield, the electromagnetic shield comprising a plurality of sections extending along different locations along the beam path, each section surrounding the charged particle beam path, and the sections being separable.

[0014]

[0014] According to a seventh aspect of the present invention, a method is provided for operating an electro-optical assembly configured to project a charged particle beam along a beam path toward a target, wherein the assembly includes a plurality of electromagnetic shielding sections configured to shield the charged particle beam from an electromagnetic field outside the electromagnetic shield, and a module comprising an electro-optical device and configured to be removable from the assembly, the method comprising removing the module from the assembly, the removal comprising moving the sections of electromagnetic shielding within the module radially relative to the beam path.

[0015]

[0015] According to an eighth aspect of the present invention, a multi-column apparatus is provided, comprising: electron-optical columns configured to project respective charged particle beams along their respective beam paths toward a target; a charged particle source configured to generate charged particle beams for one or more of the electron-optical columns; and an electromagnetic shield surrounding the charged particle beam path of at least one of the electron-optical columns, wherein the electromagnetic shield comprises a plurality of sections extending along different locations along the respective beam paths, each section surrounding a charged particle beam path, and the sections are separable.

[0016]

[0016] The advantages of the present invention will become apparent from the following description, in conjunction with the accompanying drawings, which describe specific embodiments of the present invention as examples and illustrations.

[0017]

[0017] The above and other aspects of the present disclosure will become more apparent from the description of exemplary embodiments in conjunction with the accompanying drawings. [Brief explanation of the drawing]

[0018] [Figure 1]

[0018] This is a schematic diagram showing an exemplary charged particle beam inspection apparatus. [Figure 2]

[0019] It is a schematic diagram showing an exemplary multi-beam electron optical column which is part of the exemplary inspection apparatus of FIG. 1. [Figure 3]

[0020] It is a schematic diagram of an electron optical assembly according to an embodiment. [Figure 4]

[0021] It is a schematic diagram of an electron optical assembly according to an embodiment. [Figure 5]

[0022] It is a schematic diagram of an electron optical assembly according to an embodiment. [Figure 6]

[0023] It is a schematic diagram of a part of an electron optical assembly according to an embodiment. [Figure 7]

[0024] It is a schematic diagram of an electron optical assembly according to an embodiment. [Figure 8]

[0025] It is a schematic diagram of an electron optical assembly according to an embodiment. [Figure 9]

[0026] It is a schematic diagram of an electron optical assembly according to an embodiment. [Figure 10]

[0027] It is a schematic diagram of an electron optical assembly according to an embodiment. [Figure 11]

[0028] It is a schematic diagram of an electron optical assembly according to an embodiment. [Figure 12]

[0029] It is a schematic diagram of an electron optical column according to an embodiment. [Figure 13]

[0030] It is a schematic diagram of an electron optical column according to an embodiment. [Figure 14]

[0031] It is a schematic diagram of an electron optical column according to an embodiment. [Figure 15]

[0032] It is a schematic diagram of an electron optical column according to an embodiment. [Figure 16]

[0033] It is a schematic diagram of a multi-column device according to an embodiment. [Figure 17]

[0034] This is a schematic diagram of a multi-column device according to one embodiment. [Figure 18]

[0035] This is a schematic diagram of a multi-column device according to one embodiment. [Figure 19]

[0036] This is a schematic diagram of a multi-column device according to one embodiment. [Modes for carrying out the invention]

[0019]

[0037] Hereafter, exemplary embodiments will be described in detail, examples of which are shown in the accompanying drawings. The following description will refer to the accompanying drawings, and unless otherwise indicated, 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 embodiments related to the present invention as described in the accompanying claims.

[0020]

[0038] The reduction in the physical size of devices and the improvement in 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 has been made possible by improvements in resolution, which allows for the fabrication of even smaller structures. Semiconductor IC manufacturing is a complex and time-consuming process with hundreds of individual steps. An error in any step of the process of manufacturing an IC chip can negatively affect the functionality of the final product. Just one defect can cause device failure. It is desirable to improve the overall yield of the process. For example, to obtain a 75% yield for a process with 50 steps (where a step may represent the number of layers formed on a wafer), each individual step must have a yield of over 99.4%. If each individual step has a yield of 95%, the overall process yield is low, at 7-8%.

[0021]

[0039] Maintaining a 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 to investigate defects. High-throughput detection and identification of microscale and nanoscale defects using inspection tools (such as scanning electron microscopes ("SEM")) is desirable to maintain high yield and low cost for IC chips.

[0022]

[0040] A SEM includes a scanning device and a detector. The scanning device includes an illumination device containing 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 secondary electrons and / or backscattered electrons. The detector captures secondary electrons and / or backscattered electrons from the target as the target is scanned, so that the SEM can generate an image of the scanning area of ​​the target. The design of the electron-optical tools that embody these SEM features may have a single beam. For higher throughput, such as for inspection, some designs of the device use multiple focused beams of primary electrons, i.e., multibeams. The component beams of a multibeam are sometimes called subbeams or beamlets. A multibeam can scan different parts of a target simultaneously. Therefore, a multibeam inspection device can inspect a target much faster than a single-beam inspection device, for example, by moving the target at a faster speed.

[0023]

[0041] In multibeam inspection systems, several paths of the primary electron beam are displaced away from the central axis of the scanning device, i.e., the midpoint of the primary electron optical axis (also referred to herein as the charged particle axis). To ensure that all electron beams reach the sample surface at substantially the same angle of incidence, sub-beam paths with a greater radial distance from the central axis must be manipulated to move at a larger angle than sub-beam paths closer to the central axis. This more forceful manipulation can introduce aberrations that blur the resulting image and cause it to defocus. One example is spherical aberration, which causes the focal plane of each sub-beam path to be different. Specifically, with respect to sub-beam paths not on the central axis, the change in the focal plane of the sub-beam increases with radial displacement from the central axis. Such aberrations and defocusing effects can remain associated with secondary electrons when detected from the target, affecting, for example, the shape and size of the spots formed by the sub-beams on the target. Therefore, such aberrations degrade the quality of the resulting image generated during inspection.

[0024]

[0042] The following describes known implementation configurations of multibeam inspection systems.

[0025]

[0043] The figures are schematic diagrams. Therefore, in the drawings, the relative dimensions of the components are enlarged for clarity. In the following description of the drawings, the same or similar reference numbers refer to the same or similar components or entities, and only the differences to individual embodiments are described. Although the description and drawings pertain to electro-optical devices, it is understood that the embodiments are not used to limit this disclosure to specific charged particles. Therefore, throughout this document, references to electrons and items mentioned in relation to electrons can be considered more generally as references to charged particles and items mentioned in relation to charged particles, where charged particles are not necessarily electrons.

[0026]

[0044] Referring here to Figure 1, which is a schematic diagram showing an exemplary charged particle beam inspection apparatus 100. The inspection apparatus 100 in Figure 1 includes a vacuum chamber 10, a loading lock chamber 20, an electron-optical column 40 (also known as an electron beam tool), an instrument front-end module (EFEM) 30, and a controller 50. The electron-optical column 40 may be located inside the vacuum chamber 10.

[0027]

[0045] The EFEM 30 includes a first loading port 30a and a second loading port 30b. The EFEM 30 may include one or more additional loading ports. The first loading port 30a and the second loading port 30b can receive, for example, a substrate to be inspected (e.g., a semiconductor substrate or a substrate made of other materials) or a front-opening unified pod (FOUP) containing a target (hereinafter, substrates, wafers, and samples are collectively referred to as "targets"). One or more robotic arms (not shown) of the EFEM 30 carry the target into the loading lock chamber 20.

[0028]

[0046] The loading lock chamber 20 is used to remove gas from around the target. The loading lock chamber 20 may be connected to a loading lock vacuum pump system (not shown), which removes gas particles from within the loading lock chamber 20. The operation of the loading lock vacuum pump system allows the loading 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 so that the pressure around the target reaches a second pressure below the first pressure. After reaching the second pressure, the target is carried to an electron-optic column 40, which can then be inspected by the electron-optic column. The electron-optic column 40 may include a single-beam or multi-beam electron-optic device.

[0029]

[0047] The controller 50 is electronically connected to the electron-optical column 40. The controller 50 may also be a processor (such as a computer) configured to control the charged particle beam inspection 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 as an external component of the structure including the main chamber 10, the loading lock chamber 20, and the EFEM 30, but it is understood that the controller 50 may also be part of the structure. The controller 50 may be located inside one of the component elements of the charged particle beam inspection apparatus, or the controller 50 may be distributed across at least two of the component elements. While this disclosure provides an example of a main chamber 10 housing electron beam inspection tools, it should be noted that aspects of this disclosure are not limited in a broad sense to chambers housing electron beam inspection tools. Rather, it is understood that the principles described above can be applied to other tools and other arrangements of apparatus operating under a second pressure.

[0030]

[0048] Referring here to Figure 2, Figure 2 is a schematic diagram of an exemplary multi-beam electron-optical column 40 of the inspection apparatus 100 of Figure 1. In one alternative embodiment, the inspection apparatus 100 is a single-beam inspection apparatus. The electron-optical column 40 may include an electron source 301, a beamformer array 372 (also known as a Gunn aperture plate, Coulomb aperture array, or pre-subbeamforming aperture array), a focusing lens 310, a source converter (or micro-optical array) 320, an objective lens 331, and a target 308. In one embodiment, the focusing lens 310 is magnetic. The target 308 may be supported by a support on a stage. The stage may be motorized. The stage moves so that the target 308 is scanned by accidental electrons. The electron source 301, beamformer array 372, and focusing lens 310 may also be components of an illumination apparatus included in the electron-optical column 40. The source converter 320 (also known as a source converter unit) and the objective lens 331, described in more detail below, may also be components of a projection apparatus included by an electro-optical column 40.

[0031]

[0049] The electron source 301, beamformer array 372, focusing lens 310, source converter 320, and objective lens 331 are aligned with the primary electron optical axis 304 of the electron-optical column 40. The electron source 301 can generate a primary beam 302 along approximately the electron optical axis 304 and using a (virtual or real) source crossover 301S. During operation, the electron source 301 is configured to emit electrons. The electrons are extracted or accelerated by an extractor and / or anode to form the primary beam 302.

[0032]

[0050] 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 reduced by the beamformer array 372 to a specified number of subbeams (e.g., three subbeams 311, 312, and 313). It should be understood that this description is intended to apply to electron-optical columns 40 having any number of subbeams, such as one, two, or four or more. During operation, the beamformer array 372 is configured to block peripheral electrons to reduce the Coulomb effect. The Coulomb effect can enlarge the size of probe spots 391, 392, and 393, respectively, and therefore reduce the inspection resolution. The beamformer array 372 reduces aberrations caused by Coulomb interactions between electrons projected onto the beam. The beamformer array 372 may include multiple apertures for generating primary subbeams even before the source transducer 320.

[0033]

[0051] The source converter 320 is configured to convert the beam (including any sub-beams) transmitted by the beamformer array 372 into a sub-beam projected toward the target 308. In one embodiment, the source converter is a unit. Alternatively, the term source converter may simply be used as a general term for a group of components that form a beamlet from a sub-beam.

[0034]

[0052] As shown in Figure 2, in one embodiment, the electron-optical column 40 includes a beam-limiting aperture array 321 having an aperture pattern (i.e., apertures arranged in a certain manner) configured to define the outer dimensions of beamlets (or sub-beams) projected toward the target 308. In one embodiment, the beam-limiting aperture array 321 is part of the source converter 320. In one alternative embodiment, the beam-limiting aperture array 321 is part of the up-beam system of the main column. In one embodiment, the beam-limiting aperture array 321 divides one or more of the sub-beams 311, 312, 313 into beamlets such 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 one alternative embodiment, the beam-limiting aperture array 321 maintains a 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.

[0035]

[0053] As shown in Figure 2, in one embodiment, the electron-optical column 40 includes a pre-bending deflector array 323, which has 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.

[0036]

[0054] The electron-optical column 40 may also include an image-forming element array 322 comprising 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 electron optical axis 304. The deflected beamlet forms a virtual image (not shown) of the source crossover 301S. In this embodiment, these virtual images are projected onto the target 308 by the objective lens 331 to form probe spots 391, 392, and 393 on the target. The electron-optical column 40 may also include an aberration compensator array 324 configured to compensate for any aberrations that may be present in each sub-beam. In one embodiment, the aberration compensator array 324 includes lenses configured to act on each beamlet. The lenses may take the form of a lens array. The array of lenses can act on different beamlets of the multibeam. The aberration compensator array 324 may include, for example, a field curvature compensator array (not shown) equipped with microlenses. The field curvature compensator and microlenses may be configured to compensate for individual subbeams with respect to significant field curvature at probe spots 391, 392, and 393. The aberration compensator array 324 may include an astigmatism compensator array (not shown) equipped with a microastigmatism corrector. The microastigmatism corrector may be controlled to act on subbeams to compensate for astigmatism otherwise present at probe spots 391, 392, and 393.

[0037]

[0055] The source converter 320 may further include a pre-bending deflector array 323, which comprises pre-bending deflectors 323_1, 323_2, and 323_3 for bending the sub-beams 311, 312, and 313, respectively. The pre-bending deflectors 323_1, 323_2, and 323_3 can bend the sub-beam paths toward the beam limiting aperture array 321. In one embodiment, a pre-bending microdefender array 323 may be configured to bend the sub-beam path of the sub-beam toward a plane perpendicular to the beam limiting aperture array 321. In an alternative embodiment, the focusing lens 310 may adjust the path direction of the sub-beam toward the beam limiting aperture array 321. The focusing lens 310 can, for example, focus (collimate) the three sub-beams 311, 312, and 313 so that they form a beam substantially parallel to the primary electron optical axis 304, and so the three sub-beams 311, 312, and 313 are incident substantially perpendicularly on the source converter 320, which may correspond to a beam limiting aperture array 321. In such alternative embodiments, a pre-bending deflector array 323 may not be necessary.

[0038]

[0056] The image-forming element array 322, the aberration compensator array 324, and the pre-bending deflector array 323 may include multiple layers of the sub-beam manipulating device, some of which may be in form or array form (e.g., micro-deflectors, micro-lenses, or micro-astigmatism correctors). The beam path may be rotated. Rotational compensation may be provided by magnetic lenses. Additionally or alternatively, rotational compensation may be implemented by existing magnetic lenses, such as a focusing lens configuration.

[0039]

[0057] In this example of the electron-optical column 40, the beamlet is deflected toward the electron optical axis 304 by deflectors 322_1, 322_2, and 322_3 of the image-forming element array 322, respectively. It is understood that the beamlet path may already coincide with the electron optical axis 304 before reaching the deflectors 322_1, 322_2, and 322_3.

[0040]

[0058] The objective lens 331 focuses the beamlet onto the surface of the target 308; that is, the objective lens 331 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 the target surface. 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 limit the off-axis aberration 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.

[0041]

[0059] A manipulator is configured to manipulate one or more charged particle beams. The term manipulator encompasses deflectors, lenses, and apertures. The pre-bending deflector array 323, the aberration compensator array 324, and the image-forming element array 322 are sometimes referred to as the manipulator array 34, individually or combined, because they manipulate one or more charged particle subbeams or beamlets. The lenses and deflectors 322_1, 322_2, and 322_3 are sometimes referred to as manipulators because they manipulate one or more charged particle subbeams or beamlets.

[0042]

[0060] In one embodiment, a beam separator (not shown) is provided. The beam separator may be located on the downbeam of the 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 positioned between adjacent sections 32 of the shield 31 in the direction of the beam path (described in more detail below). The inner surface 39 of the shield may be located radially inward of the beam separator. Alternatively, the beam separator may be located within the shield 31. When in operation, the beam separator may be configured to exert an electrostatic force on individual electrons of the subbeam by the electrostatic dipole field. 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 at least a substantially zero deflection angle. The direction of the magnetic force depends on the direction of electron motion, while the direction of the electrostatic force does not. Therefore, since secondary electrons and backscattered electrons generally move in the opposite direction to primary electrons, the magnetic force acting on secondary electrons and backscattered electrons no longer cancels out the electrostatic force, and as a result, secondary electrons and backscattered electrons traveling through the beam separator are deflected away from the electron optical axis 304.

[0043]

[0061] In one embodiment, a secondary column (not shown) is provided, which includes 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 directed to an image processing system (e.g., controller 50). Each detection element may include one or more pixels. The intensity signal output of the detection element may be the sum of the signals generated by all pixels within the detection element.

[0044]

[0062] In one embodiment, a secondary projection device and an associated electron detection device (not shown) are provided. The secondary projection device and associated electron detection device may be aligned with the secondary electron optical axis of the secondary column. In one embodiment, a beam separator is positioned to deflect the path of the secondary electron beam toward the secondary projection device. Subsequently, the secondary projection device focuses the path of the secondary electron beam onto multiple detection areas of the electron detection device. The secondary projection device and associated electron detection device may register and generate an image of the target 308 using secondary electrons or backscattered electrons.

[0045]

[0063] In one embodiment, the inspection device 100 includes a single source.

[0046]

[0064] Any element or group of elements may be replaceable within the electron-optical column or replaceable in the field. One or more electron-optical components within the column, particularly those that act on or generate a sub-beam, such as aperture arrays and manipulator arrays, may include one or more MEMS (microelectromechanical systems). The pre-bending deflector array 323 may also be a MEMS. MEMS are small mechanical and electromechanical elements made using microfabrication techniques. In one embodiment, the electron-optical column 40 includes 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 charged particle beamlet projected toward the target 308.

[0047]

[0065] In some embodiments, the electron-optical column 40 may include alternative and / or additional components on the charged particle path, such as lenses and other components (some of which are described earlier with reference to Figures 1 and 2). Specifically, embodiments include an electron-optical column 40 that splits a charged particle beam from a 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 in the up-beam from the objective lens. The focusing lenses focus each sub-beam to an intermediate focus in the up-beam of the objective lens. In some embodiments, a collimator is provided in the up-beam from the objective lens. Correctors may be provided to reduce focus error and / or aberrations. In some embodiments, such correctors are incorporated into the objective lens or positioned directly adjacent to the objective lens. If a focusing lens is provided, such a compensator may be additionally or alternatively incorporated into the focusing lens, positioned directly adjacent to the focusing lens, and / or positioned at an intermediate focal point, or positioned directly adjacent to an intermediate focal point. A detector is provided to detect charged particles emitted by the sample. The detector may be incorporated into the objective lens. The detector may be positioned on the bottom surface of the objective lens so as to face the sample in use. The focusing lens, objective lens, and / or detector may be formed as MEMS or CMOS devices.

[0048]

[0066] Figure 3 shows an electron-optical assembly according to one embodiment of the present invention. The electron-optical assembly is for an electron-optical column 40. The electron-optical column 40 is for projecting a charged particle beam along a beam path toward a target 308. In one embodiment, the beam path is axial to the electron-optical column 40. The axial direction coincides with the electron optical axis 304. Alternatively, the beam path may be angled with respect to the electron optical axis 304.

[0049]

[0067] As shown in Figure 3, in one embodiment, the electro-optical assembly includes an electromagnetic shield 31. The electromagnetic shield is configured to surround the charged particle beam. The electromagnetic shield 31 is configured to shield the charged particle beam from electromagnetic fields outside the electromagnetic shield 31.

[0050]

[0068] In the electro-optical column 40, the path of the charged particle beam is controlled by an electromagnetic field. For example, an internal electromagnetic field may be used to control the charged particle beam path (i.e., inside the shield 31). Thus, the internal electromagnetic field is predetermined in the design and operation of the electro-optical assembly. An external (i.e., stray) electromagnetic field may undesirably divert the charged particle beam from its intended path. Here, "external" refers to the area outside the shield. The electromagnetic shield 31 is configured to attenuate the external electromagnetic field. The electromagnetic shield 31 is configured to reduce the influence of the external electromagnetic field on the charged particle beam path.

[0051]

[0069] In one embodiment, the electromagnetic shield 31 is configured to shield a charged particle beam from an electric field. In one embodiment, the electromagnetic shield 31 includes a conductive material. For example, the electromagnetic shield 31 may include a conductive material such as a metal such as copper, nickel, iron, or cobalt, or a doped semiconductor, or a metal coating. Such a metal coating may be provided on a non-metallic material such as metal or plastic. The shield 31 may have a low-resistance connection to its ground connection. By surrounding the beam with a low-ohm material, the effects of stray electric fields can be attenuated. In one embodiment, the electromagnetic shield 31 is connected to a DC potential. In one embodiment, the DC potential is the ground potential. Alternatively, the DC potential may be a fixed potential different from ground to provide an electrostatic lens.

[0052]

[0070] In some embodiments, the electromagnetic shield 31 is configured to shield a charged particle beam from a magnetic field. In some embodiments, the electromagnetic shield 31 comprises a permeable material. For example, the electromagnetic shield 31 may comprise an alloy. The alloy may comprise nickel and / or iron and / or cobalt. In some embodiments, the electromagnetic shield 31 comprises one or more rare earth elements. In some embodiments, the electromagnetic shield 31 comprises a material having a relative permeability of at least 5,000, 10,000, optionally at least 20,000, optionally at least 50,000, and optionally at least 100,000. In some embodiments, the electromagnetic shield 31 is heat-treated. In some embodiments, the electromagnetic shield 31 undergoes a magnetic annealing process. In some embodiments, the electromagnetic shield 31 is heated in a hydrogen atmosphere.

[0053]

[0071] As shown in Figure 3, in one embodiment, the electromagnetic shield 31 includes multiple sections 32. The sections 32 of the electromagnetic shield 31 extend along multiple different locations along the beam path. In the orientation shown in Figure 3, the beam path extends from top to bottom. Three sections 32 are shown in Figure 3. The central section 32 extends along the portion of the beam path that is down-beam of the uppermost section 32 shown and up-beam of the lowermost section 32 shown. Each section 32 is configured to surround a charged particle beam. The beam may be multi-beam.

[0054]

[0072] As shown in Figure 3, in one embodiment, section 32 of the electromagnetic shield 31 is separable. By defining section 32 as separable, it is easier to disassemble parts of the electro-optical column 40 and / or replace one or more parts of the electro-optical column 40. The parts of the electro-optical column 40 can be removed one by one. Section 32 can be removed one by one to remove and / or replace parts of the electro-optical column 40. One embodiment of the present invention is expected to make maintenance of the electro-optical column 40 easier.

[0055]

[0073] In Figure 3 (and several other figures), the electromagnetic shield 31 is shown as being positioned symmetrically around the beam path. In practice, the origin and direction of the external stray magnetic field may be unknown. A symmetrical electromagnetic shield 31 may have a predetermined attenuation factor regardless of the direction of the stray magnetic field. However, for the present invention, it is not essential that the electromagnetic shield 31 be positioned symmetrically around the beam path. The electromagnetic shield may be positioned off-center from the beam path. In some cases, the direction of the external magnetic field may be known (for example, because the source of the magnetic field is known). In some embodiments, the electromagnetic shield 31 is designed to attenuate the effect of the magnetic field more in one particular direction than in another.

[0056]

[0074] As shown in Figure 3, in one embodiment, the sections 32 are arranged such that a gap 33 in the electromagnetic shield 31 is formed between adjacent sections 32 in the direction of the beam path. For example, two gaps 33 are shown between three sections 32. The three exemplary sections may be referred to as the up-beam section 32' for the up-beam of the central section 32, and the down-beam section 32'' for the down-beam of the central section 32. As shown in Figure 3, in one embodiment, the sections 32 are arranged such that at least one section 32, for example, the central section 32, is radially movable relative to the beam path, independently of another section 32, for example, the up-beam and down-beam sections 32', 32''. In the orientation shown in Figure 3, the radial direction is left-right (i.e., across the vertical ends of the page). In one embodiment, one of the sections 32 is shiftable in an angled direction, preferably perpendicular, relative to the beam path, independently of another section 32. In one embodiment, section 32 is shiftable independently of another section 32 in a direction angled with respect to the direction perpendicular to the beam path.

[0057]

[0075] One embodiment of the present invention is expected to make it easier to remove and / or replace intermediate sections along the electron-optical column 40. Disassembly and assembly can be performed by moving section 32 in an angled direction (optionally perpendicular to the beam path). Disassembly and assembly may also be possible by moving section 32 in the direction of the beam path, for example by removing sections one by one. The gap 33 makes it easier for one section 32 to be shifted into or out of the beam path independently of other sections 32 (for example, without contact with or obstruction of other sections 32). In one embodiment, the shield 31 includes an aperture through which the beam path extends. In one embodiment, the aperture has dimensions of at least 2 mm, and optionally at least 5 mm, in a direction perpendicular to the beam path. In one embodiment, the beam has dimensions within a region of 1-2 mm. The beam fits into the aperture before and after the replacement of section 32 of the shield 31.

[0058]

[0076] As shown in Figure 3, in one embodiment, adjacent sections 32 have opposing surfaces 34. The opposing surface 34 of one section faces the opposing surface 34 of an adjacent section 32 of the electromagnetic shield 31. The opposing surfaces 34 are arranged to extend away from the beam path, preferably radially with respect to the beam path. The opposing surfaces 34 of adjacent sections 32 may be parallel. In the arrangement shown in Figure 3, the opposing surfaces 34 of the uppermost and middle sections 32 extend further, preferably radially, than the opposing surfaces 34 of the middle and lowermost sections 32. In one embodiment, the opposing surfaces 34 define the extent of the gap 33 in the direction of the beam path.

[0059]

[0077] In one embodiment, the opposing surface 34 extends preferably radially away from the beam path by a distance at least equal to the size of the gap 33 between adjacent sections 32. As shown in Figure 3, the gap 33 between the uppermost section 32 and the middle section 32 has a distance D1. The distance D1 is measured in the direction of the beam path. The opposing surfaces 34 on both sides of the gap 33 extend preferably radially away from the beam path by a width W1. The width W1 is measured radially (which may be perpendicular to the direction of the beam path). The width W1 is measured from the inner surface of section 32 to the radially outer edge of the opposing surface 34. In one embodiment, W1 ≥ D1; that is, the width W1 may be greater than or equal to the distance D1.

[0060]

[0078] As shown in Figure 3, the gap 33 between the bottom and central sections 32, 32' has a distance D2 in a direction parallel to the beam path. The opposing surfaces 34 on both sides of the gap 33 extend radially (width W2) with respect to the beam path, for example. In some embodiments, W2 ≥ D2; that is, the width W2 can be greater than or equal to the distance D2.

[0061]

[0079] The radial range of the opposing surface 34 can help section 32 attenuate the effects of stray electromagnetic fields. Generally, increasing the radial range of the opposing surface 34 compared to the size of the gap 33 reduces the effects of stray electromagnetic fields. In some embodiments, the opposing surface 34 extends radially for a distance at least twice the size of the gap 33 between adjacent sections 32. In some embodiments, the opposing surface 34 extends radially for a distance at least three times the size of the gap 33 between adjacent sections 32. In some embodiments, the opposing surface 34 extends radially for a distance at least four times the size of the gap 33 between adjacent sections 32. In some embodiments, the opposing surface 34 extends radially for a distance at least five times the size of the gap 33 between adjacent sections 32.

[0062]

[0080] In the configuration shown in Figure 3, the opposing surfaces 34 on either side of the gap 33 extend equidistantly in the radial direction. However, this is not necessarily true. In some alternative embodiments, the opposing surfaces 34 on either side of the gap 33 may extend different distances in the radial direction. In some embodiments, the shorter distance of the two opposing surfaces 34 extends radially by a distance at least equal to (or twice, three times, four times, or five times) the size of the gap 33. Some embodiments of the present invention are expected to reduce the influence of stray electromagnetic fields on the beam path. In some configurations, the opposing surfaces 34 may extend non-uniformly around and relative to the beam path. For example, in radial directions opposite to the beam path, the opposing surfaces may extend further from the beam than in the other direction.

[0063]

[0081] As shown in Figure 3, in one embodiment, at least one end of section 32 in the direction of the beam path includes a flange 35 extending radially with respect to the beam path. In one embodiment, the flange 35 includes an opposing surface 34. In one embodiment, the electromagnetic shield is preferably flared, away from the beam path in the radial direction. The flange 35 helps to increase the radial range of the opposing surface 34 without unnecessarily increasing the thickness of the electromagnetic shield 31. By keeping the thickness of the electromagnetic shield 31 relatively small, the material cost of the electromagnetic shield is limited. One embodiment of the present invention is expected to reduce the effect of stray electromagnetic fields on the beam without unnecessarily increasing manufacturing costs.

[0064]

[0082] Figure 4 schematically shows a portion of an electron-optical column 40 according to one embodiment of the present invention. As shown in Figure 4, the provision of a flange is not essential. In the arrangement shown in Figure 4, the uppermost section 32' of the electromagnetic shield 31 has an outer diameter which may be constant. The opposing surface 34 extends radially. The radial range of the opposing surface 34 is provided by increasing the thickness of section 32 (compared to the central section 32). The radial range of the opposing surface 34 is provided by the thickness of the uppermost section 32. Thus, the opposing surface is provided by the wall of the shield 31. That is, the shield is a tube having an opposing surface that coincides with the end surface of the tube. Thus, the thickness of the tube can define a range of widths W1, W2 in the direction away from the beam path, at least at the end providing the wall.

[0065]

[0083] The central section 32 shown in Figure 4 is similar to the central section 32 shown in Figure 3. The bottom section 32'' shown in Figure 4 includes a flange 35. The bottom section 32 has thicker walls than the central section 32. In the bottom section 32'', the radial range of the opposing surfaces 34 is provided, on the one hand, by increasing the thickness of the bottom section 32'' (compared to the central section 32), and on the other hand, by providing the flange 35.

[0066]

[0084] As shown in Figure 4, in one embodiment, the electro-optical assembly includes at least one electro-optical element between adjacent sections 32 of the electromagnetic shield 31. The electro-optical element is configured to act on the beam path. For example, in one embodiment, one or more deflectors 36 are provided between adjacent sections 32. (The deflectors are shown in cross-section, as are the sections.) In one embodiment, one or more lenses 37 are provided between adjacent sections 32. (An electrostatic lens includes two or more plates, but for simplicity, these lenses are shown schematically.) Other types of electro-optical elements may be positioned between adjacent sections 32. A magnetic lens may include a coil on the outside of the shield 31 and a core positioned between adjacent sections 32. In one embodiment, the electro-optical elements between sections 32 are MEMS elements. For example, the deflectors 36 and / or lenses 37 may be MEMS.

[0067]

[0085] In one embodiment, the electromagnetic shield 31 is configured to extend around a multi-beam path. In one embodiment, the electromagnetic shield 31 includes a plurality of sections 32: an up-beam section 32' for the up-beam of the electro-optical element, a down-beam section 32'' for the down-beam of the electro-optical element, and an element section 32 associated with the electro-optical element. In one embodiment, the element section 32 is configured to be removable from the tool containing the electro-optical element. In one embodiment, a small gap exists between adjacent sections 32 along the beam path.

[0068]

[0086] In the embodiment shown in Figure 4, the deflector 36 acts on the beam passing through the gap 33. In the embodiment shown in Figure 4, the deflector 36 is positioned radially outward from the outer range of section 32. In one alternative embodiment, the deflector 36 may be positioned at least partially inward from the outer radial range of section 32. The outer radial range of section 32 may coincide with a length surface which may be parallel to the direction of the beam path. In one embodiment, the deflector 36 is located within the gap 33, for example, between opposing surfaces 34 that define the gap 33. Positioning the deflector 36 closer to the beam reduces the undesirable attenuation of the effect of the deflector 36 on the beam by the shield 31. In one embodiment, the deflector 36 is aligned with the inner surface 39 of section 32. In one embodiment, the deflector 36 is closer to the beam path than the inner surface 39 of section 32.

[0069]

[0087] As shown in Figure 4, in one embodiment, the lens 37 extends radially outward beyond the radially inward edge of section 32 of the electromagnetic shield 31. The outer circumference of the lens 37 is located within the gap 33. In one embodiment, the lens 37 is a lens array. Additionally or alternatively, an array of deflectors or apertures may be positioned between adjacent sections 32.

[0070]

[0088] Figure 5 shows a portion of an electro-optical column 40 according to one embodiment. As shown in Figure 5, in one embodiment, the electro-optical column 40 includes a module 405. In one embodiment, the module 405 includes an electro-optical assembly. The module 405 may include a section 32 of the electromagnetic shield 31. As shown in Figure 5, in one embodiment, the module 405 includes an electro-optical element 38. In one embodiment, the electro-optical element 38 includes one or more manipulators such as an aperture, a deflector, and a lens. The electro-optical element 38 may also be a manipulator array. In one embodiment, the electro-optical element is a MEMS element. As shown in Figure 5, in one embodiment, the section 32 in the module 405 is flared. The electro-optical element includes surface portions facing the opposing surfaces 34 of the sections 32 on both sides of the electro-optical element 38.

[0071]

[0089] In the module 405 shown in Figure 5, two sections 32 of the electromagnetic shield 31 are provided. The electro-optical element 38 is located between these sections 32. Gaps of distances D3 and D4 are formed between the sections 32 and the surface portions, i.e., the surfaces of the electro-optical element 38 in the direction of the beam path opposite the opposing surfaces of the sections 32. Together with the opposing surface portions, the opposing surfaces of the sections 32 define the corresponding gaps. The opposing surfaces that define the gaps together with the surface portion gaps extend radially by distances W3 and W4, respectively. In some embodiments, W3 is at least as large as D3. In some embodiments, W3 is twice (or three times, or four times, or five times) the size of D3. In some embodiments, W4 is at least as large as D4. In some embodiments, W4 is twice (or three times, or four times, or five times) the size of D4.

[0072]

[0090] In one embodiment, module 405 includes an electro-optical component on a stage that enables movement for positioning the component. In one embodiment, module 405 includes a stage. In one configuration, the stage and module may be an integrated part of the electro-optical column 40. In one configuration, module 405 is limited to the stage and the electro-optical device supported by the stage. In one configuration, the stage is removable. In one alternative design, module 405, including the stage, is removable. The portion of the electro-optical column 40 relating to module 405 is separable, i.e., this portion of the electro-optical column 40 is defined by an up-beam valve and a down-beam valve of module 405. The valves may be operated to separate the environment between the valves from the up-beam and down-beam vacuums of the valves, respectively, allowing module 405 to be removed from the electro-optical column 40, while maintaining the up-beam and down-beam vacuums of the portion of the column associated with module 405. In one embodiment, module 405 includes a stage. The stage is configured to support an electro-optical device with respect to the beam path. In one embodiment, module 405 includes one or more actuators. The actuators are associated with a stage. The actuators are configured to move the electro-optical device relative to the beam path. In one embodiment, the actuators are located outside the electromagnetic shield 31. In one embodiment, sections 32 of the electromagnetic shield 31 associated with the electro-optical device are provided on both sides of the stage.

[0073]

[0091] If the electro-optical device is alignable to a beam path by an actuator, at least one of the sections 32 associated with the electro-optical device may be actuated. In one embodiment, one or more actuators are configured to actuate section 32 of the electromagnetic shield 31 relative to the frame of the electro-optical column 40. The frame may be associated with a stage of module 405. In one embodiment, section 32 is actuated relative to the stage of module 405. In one embodiment, section 32 is fixed relative to the electro-optical device. At least one of the shield sections 32 may be actuated together with the electro-optical device in module 405, which may be a MEMS.

[0074]

[0092] In one embodiment, module 405 is a MEMS module. In one embodiment, module 405 is configured to be replaceable within the electro-optical column 40. In one embodiment, module 405 is configured to be replaceable in the field. Replaceable in the field is intended to mean that the module can be removed and replaced with the same or a different module while maintaining the vacuum in which the electro-optical column is located. Only the section of the column corresponding to the module is vented for the removal and reinstallation or replacement of the module.

[0075]

[0093] In one embodiment, module 405 includes an internal electro-optical shield. The module can be removed, inserted, or replaced without the need to retract the electromagnetic shield 31 along the beam path. It is not necessary for section 32 to be axially movable. In conventional arrangements, the shield is either a continuous tube that needs to be removed, or a series of adjacent sections that need to be mechanically disassembled starting from one or the other end of the electro-optical column.

[0076]

[0094] Figure 6 shows a portion of the electro-optical column 40. As shown in Figure 6, in one embodiment, the last section 32''' of the electromagnetic shield 31 for the up beam of target 308 includes a counter surface 34. The counter surface 34 faces the target 308. The counter surface 34 is positioned at a distance D5 from the target 308. The distance D5 is in the direction of the beam path. The counter surface 34 extends radially with respect to the beam path, preferably by a width W5, away from the beam path. The width W5 is measured perpendicular to the direction of the beam path. As shown in Figure 6, in one embodiment, section 32 includes a flange 35. Alternatively, as described above, the radial range of the counter surface 34 may be provided by having a thicker wall of the electromagnetic shield 31.

[0077]

[0095] In one embodiment, W5 is at least as large as D5. In another embodiment, W5 is twice (or three times, four times, or five times) the size of D5. As shown in Figure 6, in one embodiment, the target 308 extends radially for at least the same distance as the width W5. The target 308 can contribute to attenuating the effect of stray electromagnetic fields on the beam.

[0078]

[0096] Figure 7 schematically shows a portion of the electro-optical column 40 according to one embodiment. Figure 7 schematically shows the radial position of the electromagnetic shield 31 relative to other components of the electro-optical column 40. The surface of the target 308, or, if it extends beyond the outer circumference of the target 308, the surface of the target support, may extend away from the beam path. In one embodiment, the surfaces of the target and / or target support may extend away from the beam path by at least the same distance as the opposing surface 34 of the last section 32.

[0079]

[0097] As shown in Figure 7, in one embodiment, the electro-optical column 40 includes a thermal conditioner 204. The thermal conditioner 204 is configured to thermally regulate at least a portion of the electro-optical column 40. In one embodiment, the thermal conditioner 204 includes a plurality of thermal regulation channels. The channels may contain a regulating fluid configured to exchange heat with one or more other portions of the electro-optical column 40. In one embodiment, the thermal conditioner 204 is configured to remove heat generated within the electro-optical column. Alternatively, the thermal conditioner 204 may have a mode in which it can provide heat to the electro-optical column 40. In one embodiment, the thermal conditioner 204 is configured to deliver heat to different portions of the inspection tool 100. In one embodiment, the thermal conditioner is configured to thermally regulate a portion of the electro-optical column 40 so that it is maintained at a stable temperature.

[0080]

[0098] As shown in Figure 7, in one embodiment, the electromagnetic shield 31 is located radially inward of the thermal conditioner 204. The electromagnetic shield 31 is configured to shield the beam from electromagnetic fields, including the electromagnetic field generated by the thermal conditioner 204.

[0081]

[0099] As shown in Figure 7, in one embodiment, the electro-optical column 40 includes at least one pump 220. The pump 220 is configured to control the pressure within the electro-optical column 40. In one embodiment, the pump 220, for example, the pump unit of pump 220, can be connected to negative pressure to reduce the pressure within the electro-optical column 40, for example, to generate and maintain a vacuum in which the column 40 is positioned. In one embodiment, the pump 220, for example, the vent valve of pump 220, can be connected to positive pressure to increase the pressure in which the electro-optical column 40 is positioned.

[0082]

[0100] As shown in Figure 7, in one embodiment, the electromagnetic shield 31 is located radially inward of the pump 220 with respect to the beam path. The electromagnetic shield 31 is configured to shield the beam from the electromagnetic field generated by the pump 220.

[0083]

[0101] As shown in Figure 7, in one embodiment, the electron-optical column 40 includes an electron-optical element such as a collimator 5. The collimator 5 is configured to collimate the charged particle beam at least partially. Under the operation of the collimator 5, the beam path can be in the direction of an ideal beam path, i.e., a beam path that diverges at least, at least less, or even focuses. In one embodiment, the electron-optical column 40 includes an electron-optical element such as a deflector. The deflector may be configured to deflect the charged particle beam.

[0084]

[0102] As shown in Figure 7, in one embodiment, the inner surface 39 of the electromagnetic shield 31 is radially inward of an electro-optical element such as a collimator 5. The collimator 5 acts on the beam. The collimator 5 is positioned so that the electromagnetic field it generates affects the beam on the beam path. The collimator 5 is positioned between two adjacent sections 32 of the electromagnetic shield 31.

[0085]

[0103] In the configuration shown in Figure 7, the collimator 5 is radially outside the radially inner surface 39 of the electromagnetic shield 31. In one alternative embodiment, a portion of the collimator 5 (e.g., the radially inner edge of the collimator 5) is at the same radial position as at least one radially inner surface 39 of section 32 that is immediately up or down the beam. Placing the collimator 5 at the same distance as, or close to, the inner surface 39 of an adjacent section with respect to the beam path helps reduce the likelihood that the electromagnetic shield 31 will undesirably attenuate the effect of the collimator 5 on the beam.

[0086]

[0104] Figure 8 schematically shows a portion of the electro-optical column 40 according to one embodiment. Figure 8 schematically shows alternative radial positions of the electromagnetic shield 31 relative to other components of the electro-optical column 40.

[0087]

[0105] As shown in Figure 8, in one embodiment, the electromagnetic shield 31 is radially inward of the thermal conditioner 204 and the pump 220. The electromagnetic shield 31 is radially outward of the electro-optic elements such as the collimator 5. As shown in Figure 8, in one embodiment, a gap 33 between adjacent sections 32 allows for a fluid connection between the pump 220 and a volume within the electromagnetic shield 31 that is close to, and even includes, the electro-optic axis 304. As shown in Figures 7 and 8, by defining the pump 220 as being outside the electromagnetic shield 31, the electro-optic properties (e.g., voltage, current) are shielded from the beam, thus providing greater design freedom with respect to the pump 220. By defining the pump 220 as being outside the electromagnetic shield 31, the pump 220 may not be required to meet such high electro-optic requirements, thereby increasing design freedom. By defining the pump 220 as being farther away from the electromagnetic shield 31, the risk of vibrations transmitted from the pump 220 to the column 40 may be reduced. Such vibrations can negatively affect the performance of the electro-optical column 40.

[0088]

[0106] Since the electromagnetic device is located within the shield 31 and the device has a power source from outside the shield 31, the routing to the device is designed to minimize the generation of electromagnetic fields within the shield 31. For example, since two routing connections are required to be connected to the electrodes of the electromagnetic device (to complete the electrical circuit), these routings are positioned adjacent to each other so that the electromagnetic fields generated by the routings substantially cancel each other out. Therefore, if the electromagnetic device is an array, the routing to each electrode for each aperture in the array is designed so that the routing is positioned together with the routing opposite it so that the generated electromagnetic fields substantially cancel each other out.

[0089]

[0107] Figure 9 schematically shows a portion of the electro-optical column 40 according to one embodiment. Figure 9 schematically shows alternative radial positions of the electromagnetic shield 31 relative to other components of the electro-optical column 40.

[0090]

[0108] As shown in Figure 9, in one embodiment, the electromagnetic shield 31 is located radially inside the thermal conditioner 204. The electromagnetic shield 31 is located radially outside the electro-optical elements such as the pump 220 and collimator 5. By defining the pump 220 to be radially inside the electromagnetic shield 31, the vacuum around the beam can be improved.

[0091]

[0109] As shown in Figure 9, in one embodiment, a lens or an array of lenses 37 is provided between adjacent sections 32. Other types of electro-optical elements may be positioned between adjacent sections 32. In one embodiment, the electro-optical elements between sections 32 are MEMS elements. For example, the deflector 36 and / or lens 37 may be MEMS. The lens 37 may be positioned within a gap 33 between adjacent sections 32. In one arrangement, there may be multiple manipulators between adjacent sections 32. The multiple manipulators may include a collection of manipulators of the same type, such as lenses, deflectors, or astigmatism correctors, and / or different types of manipulators, such as lenses, deflectors, and / or correctors. Different manipulators may include arrays of elements. A corrector array including multiple correctors may be provided. A collimator array including multiple collimators may be provided.

[0092]

[0110] Figure 10 schematically shows a portion of the electro-optical column 40 according to one embodiment. Figure 10 schematically shows alternative radial positions of the electromagnetic shield 31 relative to other components of the electro-optical column 40.

[0093]

[0111] As shown in Figure 10, in one embodiment, the electromagnetic shield 31 is located radially outside the electro-optical elements such as the thermal conditioner 204, the pump 220, and the collimator 5. A variation of this arrangement may have the pump 220 outside the shield 31. Different arrangements of the manipulator, as depicted in Figure 9, may be applied to these arrangements.

[0094]

[0112] Figure 11 shows an electro-optical assembly as part of an electro-optical column 40 according to one embodiment. As shown in Figure 11, in one embodiment, at least two sections 32 include adjacent ends that electromagnetically engage with each other. In one arrangement, the electromagnetic engagement between adjacent sections 32 is non-contact. A gap may exist between the nearby surfaces of adjacent sections 32. The sections 32 are coupled to shield the beam from stray electromagnetic fields. The sections 32 are electromagnetically engaged so that stray electromagnetic fields cannot affect the beam within the shield 31.

[0095]

[0113] As shown in Figure 11, in one embodiment, adjacent ends are made to the size necessary for coaxial arrangement. Alternatively, section 32 does not have to be coaxial if, for example, the electromagnetic shield 31 is required to fit into a space of a particular shape within the electro-optical column 40. It is not necessarily required that the shield be symmetrically arranged around the beam path.

[0096]

[0114] As shown in Figure 11, in one embodiment, adjacent ends are made to the required size so that one end can be inserted into the other. In one embodiment, adjacent sections 32 overlap along the beam path. As shown in Figure 11, the overlap 11 may be formed between adjacent sections 32 in the direction of the beam path. The overlap ensures that external electromagnetic fields do not undesirably affect the beam, such as by diverting it from the beam path.

[0097]

[0115] In one embodiment, adjacent ends of adjacent sections 32 are physically separated from each other. In another embodiment, adjacent ends are electromagnetically engaged with each other. The sections 32 are movable in the direction of the beam path. The sections 32 can be removed or replaced one by one for maintenance of the portion of the electro-optical column 40.

[0098]

[0116] In one configuration, the electromagnetic shield 31 includes different types of sections 32, such as sections with gaps between adjacent sections and sections that engage coaxially with adjacent sections. In such a configuration, the shield 31 may include sections in a module that may be removable from the electro-optical column 40. In such a configuration, a section may be adapted to have, at one end, a coaxially engaging surface with an adjacent section and at the other end, a facing surface that faces the opposing surface of the adjacent section.

[0099]

[0117] In one embodiment, the electromagnetic shield 31 described herein can be applied to a tool featuring one or more MEMS electro-optical elements, such as a MEMS objective lens.

[0100]

[0118] As described above, in some embodiments, the electron-optical column 40 may include alternative and / or additional components on the charged particle path, such as lenses and other components (some of which are described earlier with reference to Figures 1 and 2). Specifically, embodiments include an electron-optical column 40 that generates a plurality of subbeams from a charged particle beam from a source. In some embodiments, an electromagnetic shield 31 is configured to surround all the subbeams at a given position within the electron-optical column 40. In some alternative embodiments, each subbeam is given its own surrounding electromagnetic shield 31. In some embodiments, one group of subbeams of a multibeam is given an electromagnetic shield 31, preferably comprising a series of sections 32. In some embodiments, the subbeams of a multibeam are assigned groups so that the multibeam consists of multiple groups of subbeams. Multiple groups of subbeams may have a shield 31 designed with a series of sections along and around the path of each group's subbeam.

[0101]

[0119] In one embodiment, the electromagnetic shield 31 has a circular cross-section. Alternatively, the cross-sectional shape may be rectangular, square, or a rectangle with rounded corners, or a square with rounded corners.

[0102]

[0120] For example, in Figures 3-5, the inner diameter is the same for all sections 32. Alternatively, the inner diameter may vary from section to section. This may help reduce the volume of the electromagnetic shield 31.

[0103]

[0121] In one embodiment, sections 32 are aligned concentrically along the beam path. In an alternative embodiment, one or more sections 32 may be off-center relative to each other. This may result in a magnetic lensing effect on the beam.

[0104]

[0122] In some embodiments, separate electrostatic and magnetic shields are provided. The electrostatic shield is configured to shield the beam from an electrostatic field. The magnetic shield is configured to shield the beam from a magnetic field. The electrostatic shield may have the features described above with respect to the electromagnetic shield 31. The magnetic shield may have the features described above with respect to the electromagnetic shield 31. In some embodiments, the magnetic shield is located radially outward from the electrostatic shield. Alternatively, the magnetic shield may be located radially inward from the electrostatic shield. In further arrangements, the magnetic and electrical shields may be combined into a single shield set.

[0105]

[0123] As described above, in one embodiment, a secondary column (not shown) is provided, which includes a detection element for detecting the corresponding secondary charged particle beam. In one embodiment, an electro-optical assembly including an electromagnetic shield may be provided as part of the secondary column. For example, the source and / or detector of the secondary column may have the electromagnetic shield described above, except as specified herein. The shield does not need to extend up beam of the source. The shield does not need to extend down beam of the detector. In one embodiment, a Wien filter is housed by a shield 31 having a Y-shaped section. The Y-shaped section may include multiple sections that can be made easier to manufacture and assemble. In one embodiment, the section has a flange as described above. In one embodiment, the section is replaceable in the field. In one alternative embodiment, the flange may be used to bolt the section to a frame or to the sections to each other.

[0106]

[0124] Figure 12 is a schematic diagram of an electron-optical column 4 according to one embodiment. As shown in Figure 12, in one embodiment, there are multiple sections 32a to 32d of the electromagnetic shield 31. The sections 32a to 32d are located at different positions along a direction parallel to the beam path. The different sections 32a to 32d correspond to different parts of the electron-optical column 40.

[0107]

[0125] For example, in one embodiment, the first section 32a corresponds to the source portion of the electron-optical column 40. The source portion of the electron-optical column 40 extends from the source 301. The source 301 is configured to generate a primary beam 302 of charged particles. As shown in Figure 12, in one embodiment, the cross-sectional area of ​​the primary beam 302 increases until the primary beam 302 is collimated. In one embodiment, the first section 32a extends in a direction parallel to the beam path to the location where the primary beam 302 is collimated. In one embodiment, the first section 32a radially surrounds the source 301. Alternatively, the up-beam end of the first section 32a is in the down-beam of the source 301. The down-beam end of the first section 32a is in the up-beam of a collimator configured to collimate the primary beam 302.

[0108]

[0126] In one embodiment, the second section 32b corresponds to the collimator portion of the electron-optical column 40. The collimator portion of the electron-optical column 40 extends from the collimator. In one embodiment, the collimator includes a focusing lens 310 (for example, as shown in Figure 2). In one embodiment, the focusing lens 310 is magnetic. As shown in Figure 12, in one embodiment, the cross-sectional area of ​​the collimated beam may remain substantially constant in the down beam of the collimator until the primary beam 302 is split into a sub-beam 311. In one embodiment, the second section 32b extends in a direction parallel to the beam path to where the primary beam 302 is split. In one embodiment, the up beam end of the second section 32b is in the up beam of the collimator. The second section 32b may radially surround the collimator. Alternatively, the up beam end of the second section 32b may be in the down beam of the collimator. The downbeam end of the second section 32b is located in the upbeam of a beam limiting aperture array 321 configured to split the primary beam 302.

[0109]

[0127] In one embodiment, the third section 32c corresponds to the beam splitter portion of the electron-optical column 40. The beam splitter portion of the electron-optical column 40 extends from a component configured to form subbeams 311, such as a beam limiting aperture array 321. As shown in Figure 12, in one embodiment, six subbeams 311 may be formed in the downbeam of the beam limiting aperture array 321. Those skilled in the art will understand that any number of subbeams, such as hundreds or thousands, may be formed. The cross-sectional area of ​​the subbeams 311 may remain substantially constant throughout the length of the third section 32c. In one embodiment, the third section 32c extends in a direction parallel to the beam path to where the subbeams 311 are focused onto the target 208. In one embodiment, the upbeam end of the third section 32c is in the upbeam of the beam limiting aperture array 321 (or other beam splitter). The third section 32c may radially surround the beam limiting aperture array 321. Alternatively, the up-beam end of the third section 32c may be on the down-beam of the beam limiting aperture array 321. The down-beam end of the third section 32c is on the up-beam of the objective lens configured to focus the sub-beam 311 onto the target 208.

[0110]

[0128] In one embodiment, the fourth section 32d corresponds to the objective lens portion of the electro-optical column 40. The objective lens portion of the electro-optical column 40 extends from a component configured to manipulate the sub-beam 311 to control the characteristics of the sub-beam 311 incident on the target 208, for example, an objective lens 331 (as shown in Figure 2). As shown in Figure 12, in one embodiment, the sub-beam 311 is focused to the down-beam of the objective lens 331. The cross-sectional area of ​​the sub-beam 311 may decrease through at least a portion (and optionally all) of the length of the fourth section 32d. In one embodiment, the fourth section 32d extends in a direction parallel to the beam path to the point where the sub-beam 311 is incident on the target 208. In one embodiment, the up-beam end of the fourth section 32d is in the up-beam of the objective lens 331 (or other manipulator). The fourth section 32d may surround the objective lens 331, for example, radially. Alternatively, the up-beam end of the fourth section 32d may be on the down-beam of the objective lens 331. The down-beam end of the fourth section 32d is on the up-beam of the target 208.

[0111]

[0129] In each section of the electro-optical column 40, the charged particle beam is shielded from the external field by sections 32a-32d of the electromagnetic shield 31. While four sections, each having four corresponding sections 32a-32d, are shown in the arrangement in Figure 12, a different number of sections 32 may exist. For example, the beam length may be divided into two, three, or five or more sections, each having a corresponding section 32 of the electromagnetic shield 31. In some arrangements, the shielding sections may extend from the beam-limiting aperture array to the downbeam of the objective lens array.

[0112]

[0130] As described above, section 32 does not overlap in a direction parallel to the beam path. In one embodiment, the electron-optical column 40 is arranged so that at least one of its parts can be replaced without the need to handle or move the other parts. As described above in relation to Figures 3 and 4, in one embodiment, section 32 is flared at the end facing the gap 33 between adjacent sections 32. By providing a flared end, the reduction in shielding effect caused by the gap 33 can be reduced.

[0113]

[0131] In one embodiment, at least one of sections 32a to 32d radially surrounds at least one component selected from the group consisting of a charged particle source 301, a focusing lens 310, a collimator, a source transducer 320, a deflector array 323, an aperture array 321, an aberration compensator array 324, an image-forming element array 322, an objective lens 331 or an objective lens array, and a detector array. In one embodiment, the component is a MEMS component.

[0114]

[0132] In some embodiments, at least one of sections 32a-32d is positioned to move radially with respect to the beam path, together with the components it surrounds, independently of any other section 32a-32d. For example, as shown in Figure 12, in some embodiments, the electro-optical column 40 includes a collimator module 405b. In some embodiments, the collimator module 405b includes a second section 32b and a collimator. In some embodiments, the second section 32b and the collimator are fixed relative to each other. The second section 32b is field-replaceable together with the collimator. As shown in Figure 12, in some embodiments, the electro-optical column 40 includes an objective lens module 405d. In some embodiments, the objective lens module 405d includes a fourth section 32d and an objective lens 331 (or objective lens array). In some embodiments, the fourth section 32d and the objective lens are fixed relative to each other. The fourth section 32d is field-replaceable together with the objective lens.

[0115]

[0133] Although not shown in Figure 12, in one embodiment, the electro-optical column 40 includes a source module and / or a beam splitter module corresponding to the source portion and beam splitter portion described above, respectively.

[0116]

[0134] In one embodiment, each module 405 is replaceable in the field. In another embodiment, each module 405 is slidable out of the electron-optical column 40, and the replacement module is slidable in the electron-optical column 40. The sliding may be in a direction perpendicular to the beam path, for example, lateral in the orientation shown in Figure 12.

[0117]

[0135] By defining module 405 as replaceable, one embodiment of the present invention is expected to make maintenance of the electro-optical column easier and / or less expensive. One embodiment of the present invention is expected to reduce the time and / or effort required to revert and redo in order to replace one or more components of the electro-optical column 40.

[0118]

[0136] As shown in Figure 12, in one embodiment, the electro-optical column 40 includes a chimney member 52. In one embodiment, the chimney member 52 includes the same material as section 32 of the electromagnetic shield 31. The chimney member 52 is configured to protect the beam path. For example, the chimney member 52 may electromagnetically shield the beam path. As shown in Figure 12, in one embodiment, the chimney member 52 includes a hole defined, for example, in a plane or plate, through which control wires may extend. The control wires may be for controlling the electro-optical components of the electro-optical column 40. The surface of the plate defining the hole may be flared.

[0119]

[0137] As shown in Figure 12, in one embodiment, intentional gaps 33b to 33d are provided between adjacent sections 32a to 32d. In one embodiment, gaps 33a and 33e are provided at both ends of the shield 31. In one embodiment, a first gap 33a is provided between the chimney member 52 and the first section 32a. In one embodiment, a second gap 33b is provided between the first section 32a and the second section 33b. In one embodiment, a third gap 33c is provided between the second section 32b and the third section 33c. In one embodiment, a fourth gap 33d is provided between the third section 32c and the fourth section 33d. In one embodiment, a fifth gap 33e is provided between the fourth section 32d and the target 208. Some embodiments of the present invention are expected to enable easier replacement of one or more components of the electro-optical column 40. One embodiment of the present invention is expected to reduce the amount of movement required for one or more components to be replaced. The gap 33 can facilitate the movement of module 405 relative to other components of the electro-optical column 40.

[0120]

[0138] As shown in Figure 12, the intentional gap 33e is provided adjacent to the target 208. In one embodiment of the present invention, it is expected that the possibility of the electromagnetic shield 31 undesiringly coming into contact with the target 208 will be reduced. The presence of the fourth gap 33d between the third section 32c and the fourth section 32d will allow the shield sections 32c and 32d to be made nominally shorter. In one embodiment of the present invention, it is expected that the sections 32c and 32d will be less crowded during assembly.

[0121]

[0139] Figure 13 is a schematic diagram of an electro-optical column 40 according to one embodiment of the present invention. For brevity, the description of the same features described above in relation to Figure 12 is omitted. As shown in Figure 13, in one embodiment, there are four sections 32a to 32d of the electromagnetic shield 31. The four sections 32a to 32d relate to different parts of the electro-optical column 40. There is a first section 32a relating to a source portion in which a source 301 is provided. There is a second section 32b relating to a collimator portion in which the beam is collimated by a collimator, for example, a focusing lens 310. There is a third section 32c relating to a beam splitter portion in which the beam is split. For example, in the embodiment shown in Figure 13, the electro-optical column 40 includes an upper beam limiter 252. 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 up beam beam limiting aperture array. The upper beam limiter 252 may include a plate (which may be a plate-like structure) having multiple apertures. The upper beam limiter 252 forms a subbeam from the charged particle beam emitted by the source 301. The portion of the beam other than the portion contributing to the formation of the subbeam can be blocked (e.g., absorbed) by the upper beam limiter 252 so as not to interfere with the downbeam subbeam. The upper beam limiter 252 is sometimes called a subbeam defining aperture array.

[0122]

[0140] As shown in Figure 13, in one embodiment there is a control lens array 250. Such an arrangement is described in European Patent Application Publication No. 20196714.8, filed on 17 September 2020, which is incorporated herein by reference at least with respect to the electro-optical architecture shown in relation to three different embodiments shown in Figures 3, 5, and 6 of this application. 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 their respective potential sources. The control lens array 250 may also include two or more (e.g., three) plate electrode arrays connected to their respective potential sources. The control lens array 250 is associated with the objective lens array 241 (e.g., these two arrays are positioned close to each other and / or mechanically connected to each other and / or controlled together as a unit). The control lens array 250 is positioned in the up beam of the objective lens array 241. The control lens prefocuses the subbeam (for example, by applying a focusing action to the subbeam before it reaches the objective lens array 241). Prefocusing can reduce the divergence of the subbeam or increase its convergence rate.

[0123]

[0141] A fourth section 32d is provided relating to the objective lens portion which is operated in preparation for the sub-beam to be incident on the target 208. An objective lens array 241, including multiple objective lenses, is provided to guide the sub-beam onto the sample 208. Each objective lens includes at least two electrodes (e.g., two or three electrodes) connected to its respective potential source. The objective lens array 241 may include two or more (e.g., three) plate electrode arrays connected to its respective potential source. In one embodiment, as shown in Figure 13, the objective lens array 241 may include a beam shaping limiter 242. The beam shaping limiter 242 defines an array of beam limiting apertures. The beam shaping limiter 242 may be called a lower beam limiter, lower beam limiting aperture array, or last beam limiting aperture array. The beam shaping limiter 242 may include a plate (which may be a plate-like body) having multiple apertures. The beam shaping limiter 242 is located in the down beam from at least one electrode of the control lens array 250 (optionally from all electrodes). In some embodiments, the beam shaping limiter 242 is located in the down beam from at least one electrode of the objective lens array 241 (optionally from all electrodes).

[0124]

[0142] Figure 14 is a schematic diagram of an electro-optical column 40 according to one embodiment of the present invention. For brevity, a description of the same features described above in relation to Figure 12 is omitted. As shown in Figure 14, in one embodiment, seven sections 32a to 32g of the electromagnetic shield 31 are provided. The seven sections 32a to 32g relate to different parts of the electro-optical column 40. A first section 32a is provided, relating to the source portion in which the source 301 is provided. A second section 32b is provided, relating to the concentrator portion. As shown in Figure 14, in one embodiment, a concentrating lens array 231 is provided between the source 301 and the control lens array 250. Such an arrangement is described in European Patent Application Publication No. 20206984.5, filed November 11, which is incorporated herein by reference at least with respect to the electro-optical architecture shown in Figure 4 of this application. The concentrating lens array 231 includes a plurality of concentrating lenses. Dozens, hundreds, or thousands of focusing lenses may exist. The focusing lenses may include multi-electrode lenses and may have a structure based on European Patent Application Publication No. 1602121A1, which is incorporated herein by reference in particular for disclosure of lens arrays for splitting an electron beam into multiple sub-beams (the array providing one lens for each sub-beam). A second section 32b may surround the focusing lens array 231. The focusing lens array 231 is configured to split the main beam into sub-beams 311-313.

[0125]

[0143] A third section 32c relating to the control lens array 250 is provided. A fourth section relating to the objective lens portion is provided. For example, the fourth section 32d may surround the objective lens array 241, similar to the embodiment shown in Figure 13.

[0126]

[0144] As shown in Figure 14, in one embodiment, a fifth section 32e is provided between the second section 32b and the third section 32c. The fifth section 32e may surround the deflector 235, which is located at the intermediate focus. The deflector 235 is configured to bend each subbeam 311-313 by an amount effective in ensuring that the principal rays are incident on the sample 208 substantially perpendicularly (i.e., substantially at 90° with respect to the nominal plane of the sample). The deflector 235 is sometimes also called a collimator.

[0127]

[0145] As shown in Figure 14, in one embodiment, a sixth section 32f is provided between the third section 32c and the fourth section 32d. The sixth section 32f may surround the scanning deflector array 260. The scanning deflector array 260 includes a plurality of scanning deflectors. The scanning deflector array 260 may be formed using MEMS fabrication techniques. Each scanning deflector scans its respective sub-beam over the sample 208. Thus, the scanning deflector array 260 may include a scanning deflector for each sub-beam. Each scanning deflector can deflect the sub-beam in one direction (e.g., parallel to a single axis such as the X-axis) or in two directions (e.g., relative to two non-parallel axes such as the X-axis and Y-axis). The deflection is such that the sub-beam is scanned in one or two directions (i.e., one-dimensionally or two-dimensionally) across the sample 208.

[0128]

[0146] As shown in Figure 14, in one embodiment, a seventh section 32g is located between the fourth section 32d and the target 208. The seventh section 32g may surround a detector module 402. The detector module 402 detects charged particles emitted from the sample 208. The detector module 402 includes a plurality of detector elements (e.g., sensor elements such as capture electrodes). In this embodiment, the detector module 402 is located on the output side of the objective lens array 241. The output side is the side facing the sample 208. Depending on the variation, adjacent sections and modules may be combined. For example, one section may surround an objective lens array assembly that may include the detector module 402, the objective lens array, optionally a control lens array 250, and optionally a scanning deflector.

[0129]

[0147] Similar to the embodiments described above in relation to Figures 12 and 13, in the embodiment shown in Figure 14, each section 32a to 32g can move in and out of the electro-optical column 40 together with its associated components. The electro-optical column 40 is modular. An intentional gap 33 is provided between sections 32a to 32g. This facilitates the movement of sections 32a to 32g relative to each other when sections 32a to 32g are moved in or out of the electro-optical column 40.

[0130]

[0148] Figure 15 is a schematic diagram of an electron-optical column according to one embodiment of the present invention. As shown in Figure 13, in one embodiment, at least one of the sections 32 comprises mechanical reference members 51c, 51d configured to enable the position of section 32 to be determined. In one embodiment, the mechanical reference members 51c, 51d are configured to enable the position of section 32 to be determined in a direction perpendicular to the beam path. In one embodiment, the mechanical reference members 51c, 51d are configured to enable the position of section 32 to be determined in a direction parallel to the beam path. A third section 32c comprises an associated mechanical reference member 51c. A fourth section 32d comprises associated mechanical reference members 51d, 51e. Although not shown in Figure 15, in one embodiment, the third section 32c may comprise a further mechanical reference member for determining the position of the third section 32c relative to the second section 32b. Each section 32 may comprise one or more mechanical reference members 51.

[0131]

[0149] In one embodiment, the mechanical reference member 51 is fixed to the associated section 32 of the shield 31. The mechanical reference member 51 may be indirectly fixed to the associated section 32 of the shield 31. For example, the mechanical reference member 51 may be fixed to the electro-optical component surrounded by section 32, or to the frame to which the component and section 32 are fixed. In one embodiment, the position of the component or frame is determined by the mechanical reference member 51, and the position of section 32 of the shield 31 is derived from its position relative to the component or frame.

[0132]

[0150] In one embodiment, a mechanical reference member 51c is configured to mechanically engage with another mechanical reference member 51d of section 32d or a corresponding mechanical reference member 51d of column 40. For example, the mechanical reference members 51c, 51d may include complementary surfaces configured to engage with each other. In one embodiment, these surfaces are flat. In an alternative embodiment, the surfaces are configured to restrict movement perpendicular to the beam path, for example, by mutual engagement between adjacent sections. In one embodiment, one of the surfaces includes a groove into which the complementary shapes of the complementary surface fit. This restricts the lateral movement of sections 32c, 32d relative to each other. In one embodiment, these surfaces are configured to restrict movement of two degrees of freedom perpendicular to the beam path. For example, one of the surfaces may include a recess into which the hemispherical shape of the complementary surface fits. One mechanical reference member 32d may dock with the other mechanical reference member 51c.

[0133]

[0151] It is not essential that the mechanical reference members 51 mechanically engage with each other. In some embodiments, the mechanical reference members 51 include a reflective surface for reflecting radiation used in distance measurement. Distance measurement may be, for example, measuring the vertical position of section 32d relative to a target 208 or another section 32c. In some embodiments, interference measurement is performed using the mechanical reference members 51.

[0134]

[0152] In one embodiment, the mechanical reference member 51 includes a conductive material and / or dielectric suitable for capacitance measurement. Capacitance measurement can be performed to determine the position of the mechanical reference member 51 and thereby the position of section 32.

[0135]

[0153] In one embodiment, one or more sections 32 are fixed in place within the column 40. In another embodiment, one or more mechanical fastening points are configured to secure section 32 within the column 40. For example, rails, bolts, and / or preload springs are provided to control the position of section 32.

[0136]

[0154] Figure 16 is a schematic diagram of a beam inspection apparatus 100 including multiple electron-optical columns 40. The apparatus 100 is sometimes referred to as a multi-column apparatus. Figure 16 shows an embodiment in which the apparatus 100 includes three electron-optical columns 40a to 40c. In one alternative embodiment, the apparatus 100 includes two or four or more electron-optical columns 40.

[0137]

[0155] In one embodiment, each column 40a-40c includes a source 301a-301c. Alternatively, two or more columns 40 may share a common source 301. In one embodiment, each column 40a-40c has a main beam generated by the sources 301a-301c. The main beam is collimated and then split into sub-beams 311a-311c, 312a-312c, and 313a-313c, which are incident on the target 208.

[0138]

[0156] As shown in Figure 16, columns 40a to 40c can be considered as being divided into different parts. Each part has corresponding sections 32a to 32c of the shield 31. In one embodiment, at least one of sections 32a to 32c radially surrounds the beam paths of two or more of the electron-optical columns 40a to 40c. For example, the first section 32a surrounds the source portions of all three columns 40a to 40c. Sources 310a to 310c are configured to generate main beams 302a to 302c for each of the columns 40a to 40c. The second section 32b surrounds the collimator portions of all three columns 40a to 40c. The third section 32c surrounds the beam splitter portions of all three columns 40a to 40c. The number of different parts and corresponding sections 32 may be two, four, five, six, seven, or eight or more, that is, as few or as many as necessary.

[0139]

[0157] In the embodiment shown in Figure 16, all sections 32 surround the beam paths of all columns 40. However, this is not necessarily the case. For example, one or more sections 32 may surround the beam path of only one of the columns 40. This is shown, for example, in Figure 19.

[0140]

[0158] As shown in Figure 16, in one embodiment, the apparatus 100 includes a source module 405a. The source module 405a includes a first section 32a. In one embodiment, the source module 405a includes sources 301a to 301c. The source module 405a is interchangeable independently of the other modules 405b and 405c. In one embodiment, the apparatus 100 includes a collimator module 405b. The collimator module 405b includes a second section 32b. In one embodiment, the collimator module 405b includes one or more collimators configured to collimate the main beams 302a to 302c. The collimator module 405b is interchangeable independently of the other modules 405a and 405c. In one embodiment, the apparatus 100 includes a beam splitter module 405c. The beam splitter module 405c includes a third section 32c. In one embodiment, the beam splitter module 405c includes one or more beam splitters configured to split the main beams 302a-302c into sub-beams 311-313. The beam splitter module 405c is interchangeable independently of the other modules 405a, 405b.

[0141]

[0159] Figure 17 is a schematic diagram of an inspection beam apparatus 100 according to one embodiment of the present invention. The apparatus 100 is a multi-column apparatus. Figure 17 shows three columns 40a to 40c. In alternative embodiments, the number of columns 40 may be two, four, or five or more.

[0142]

[0160] As shown in Figure 17, in one embodiment, the apparatus includes six sections 32 of the shield 31 relating to different parts of the column 40. A first section 32a relating to the source portion is provided. The first section 32a and sources 301a-301c may be integrated in a source module that is independently replaceable from the rest of the apparatus 100. A third section 32c relating to the beam splitter portion is provided. The third section 32c and the upper beam limiter 252 may be integrated in a beam splitter module that is independently replaceable from the rest of the apparatus 100.

[0143]

[0161] A fifth section 32e is provided relating to the collimator portion, in which the collimator element array 271 is provided. Each collimator element collimates its respective sub-beam. Therefore, providing the collimator element array 271 and the (described) scanning deflector array 260 together may result in space savings.

[0144]

[0162] An eighth section 32h is provided relating to the control lens portion of the column 40, which is provided with the control lens array 250. The eighth section 32h and the control lens array 250 may be integrated in a control lens module that is replaceable independently of the rest of the apparatus 100. In some embodiments, similar to the embodiment shown in Figure 14, a sixth section 32f relating to the scanning deflector portion of the column 40 is provided. In some embodiments, the sixth section 32f may be combined with the scanning deflector array 260 in a scanning deflector module that is replaceable independently of the rest of the apparatus 100. In some embodiments, similar to the embodiment shown in Figure 13, a fourth section 32d corresponds to the objective lens portion of the electro-optical column 40. The fourth section 32d may be combined with the objective lens array 241 in an objective lens module that is replaceable independently of the rest of the apparatus 100.

[0145]

[0163] Figure 17 shows an arrangement having a column that is electrostatically equivalent to the arrangement illustrated and described with respect to Figure 13, although the column may be any suitable electro-optical column, such as those shown and described with respect to Figure 14. The number of shielding sections may be adjusted to the number of different modules that require field-replaceable functionality.

[0146]

[0164] Figure 18 is a schematic diagram of an inspection beam apparatus 100 according to one embodiment of the present invention. The apparatus 100 is a multi-column apparatus. Figure 18 shows three columns 40a to 40c. In alternative embodiments, the number of columns 40 may be two, four, or five or more, for example, 20 or 100 or more. For brevity, the description of the same features described above in relation to Figure 16 is omitted.

[0147]

[0165] In the embodiment shown in Figure 16, the beam paths of all columns 40 are radially surrounded by section 32. However, this is not always the case. As shown in Figure 18, in some embodiments, the beam path of at least one of the electron-optical columns 40 lies radially outside at least one section 32. For example, the beam paths of the second column 40b and the third column 40c are radially outside the first section 32a provided for the first column 40a. In some embodiments, at least one section 32 radially surrounds the beam path of only one of the electron-optical columns 40. For example, the first section 32a of the first column 40a radially surrounds the beam path of only the first column 40a.

[0148]

[0166] As shown in Figure 18, in one embodiment, different sections 32 of the electromagnetic shield 31 radially surround the beam paths of each different electro-optical column 40, and these different sections 32 are positioned to overlap in a direction parallel to the beam paths. For example, as shown in Figure 18, in one embodiment, the second section 32b of the first column 40a radially surrounds the beam path of only the first column 40a. The third section 32c of the first column 40a radially surrounds the beam path of only the first column 40a. The first section 32a' of the second column 40b radially surrounds the beam path of only the second column 40b. The second section 32b' of the second column 40b radially surrounds the beam path of only the second column 40b. The third section 32c' of the second column 40b radially surrounds the beam path of only the second column 40b. The first section 32a'' of the third column 40c radially surrounds the beam path of the third column 40c only. The second section 32b'' of the third column 40c radially surrounds the beam path of the third column 40c only. The third section 32c'' of the third column 40c radially surrounds the beam path of the third column 40c only.

[0149]

[0167] As shown in Figure 18, in one embodiment, multiple sections 32 located in overlapping positions in a direction parallel to the beam path are arranged to be able to move together radially relative to the beam path independently of any other section 32. For example, in one embodiment, all of the first sections 32a, 32a', and 32a'' are movable together. The first sections 32a, 32a', and 32a'' may be fixed relative to each other. The first sections 32a, 32a', and 32a'' may be integrated into an integrated source module that is interchangeable independently of other modules of the device 100.

[0150]

[0168] Similar to the embodiments described above and shown in Figures 12-17, sections 32 relating to different parts of columns 40a-40c are provided. Sections 32 can be replaced independently of other sections 32. Sections 32 may be combined with corresponding components in modules that are replaced independently of other modules. For example, as shown in Figure 18, in one embodiment, the second section 32b'' of the third column 40c may be combined with a collimator in a collimator module 405b'' that is replaced independently of other modules. Not shown in Figure 18, in one embodiment, each section 32 corresponds to a separate module of the device 100. In variations of the embodiments shown in and described with respect to Figure 18, multiple groups of columns may correspond to the positions of each column depicted, for example, in columns across a multi-column arrangement, in a grid such that each cell in the grid may have multiple columns, or both. Sections surrounding each group of columns may have features and functions as described and illustrated with respect to Figure 17.

[0151]

[0169] Figure 19 is a schematic diagram of an inspection beam apparatus 100 according to one embodiment of the present invention. The apparatus 100 is a multi-column apparatus. Figure 19 shows three columns 40a to 40c. In alternative embodiments, the number of columns 40 may be two, four, or five or more, for example, 25 or 100 or more. For brevity, descriptions of the same features described above in relation to Figures 16 to 18 are omitted.

[0152]

[0170] In the embodiments shown in Figures 16-17, each section 32 of the shield 31 surrounds the beam path of multiple columns 40. In the embodiment shown in Figure 18, each section 32 surrounds the beam path of only one column 40. These features are integrated in the embodiment shown in Figure 19. As shown in Figure 19, in one embodiment, a single first section 32a is provided for the source portions of multiple columns 40a-40c. Separate second sections 32b, 32b', 32b'' are provided for the collimator portions of each column 40a-40c. Separate third sections 32c, 32c', 32c'' are provided for the beam splitter portions of each column 40a-40c.

[0153]

[0171] In one embodiment, each section corresponds to a separate module that can be independently replaced. For example, as shown in Figure 19, in one embodiment, the second section 32b'' of the third column 40c may be combined with a collimator in a collimator module 405b'' that can be independently replaced from other modules.

[0154]

[0172] Although not shown in Figure 19, in one embodiment, one section 32 may be provided for a particular portion of one column 40, while another section 32 may be provided to surround the beam path of the same type of portion of multiple other columns 40. For example, the first section 32a may surround the beam path in the source portion of only the first column 40a, while further sections 32 may surround the beam path in the source portions of both the second column 40b and the third column 40c.

[0155]

[0173] As described above, in some embodiments, there may be four or more columns 40, for example nine or more, or 100 or more. In some embodiments, the first section 32a surrounds the beam path of the source portions of the first plurality of columns 40. Meanwhile, a further section 32 may surround the beam path of the source portions of a second plurality of columns 40. Of course, this feature may also be applied to other parts of the column 40, such as the collimator portion.

[0156]

[0174] In the variations of arrangement shown in and described with respect to Figure 19, a single column may refer to a group of columns in a multi-column arrangement, as described, for example, with respect to Figure 18.

[0157]

[0175] One embodiment of the present invention is expected to provide advantages with respect to a multi-column multi-beam inspection beam apparatus 100. As shown in Figures 16-19, in one embodiment, multiple multi-beam columns 40 are configured to inspect different locations on the same target 208, or different locations on different targets 208. In one embodiment, the electro-optical components of the columns 40 (e.g., focusing lenses, objective lenses) are MEMS. One embodiment of the present invention is expected to reduce and / or limit the respective radial ranges of the individual columns 40.

[0158]

[0176] In one embodiment, the MEMS component is replaceable in the field. One embodiment of the present invention is expected to facilitate maintenance of apparatus 100, which includes a fragile component that may be susceptible to contamination by particulate matter present in the ambient atmosphere, for example.

[0159]

[0177] Figures 16-19 show a few specific combinations of parts. Any other combination of field-replaceable arrays and individually replaceable parts is, of course, also possible.

[0160]

[0178] Multiple electro-optical elements, such as a beam splitter and micro-astigmatism correction device, or an objective lens and detector, or an objective lens and detector and height sensor, can also be integrated into the interchangeable portion of the array in the column 40.

[0161]

[0179] In any of the field-replaceable parts or arrays shown above, section 32 may be flared as described above. In some embodiments, two or more sections 32 may be combined within a replaceable module. For example, one section 32 may be provided on the up beam of an electro-optical component, and one section may be provided on the down beam of an electro-optical component. Section 32 may be combined with a component in a field-replaceable module.

[0162]

[0180] The electron-optical column 40 or multi-column apparatus may be a component of an inspection (or metro inspection) tool, or part of an electron beam lithography tool. The multi-beam charged particle apparatus can be used for many different applications, including not only SEM but also electron microscopy in general and lithography.

[0163]

[0181] Throughout the embodiments, the electron optical axis 304 is described. This electron optical axis 304 represents the path of charged particles passing through and being output from the source 301. All subbeams and beamlets of the multibeam may be substantially parallel to the electron optical axis 304, at least through the manipulator. The electron optical axis 304 may be the same as or different from the mechanical axis of the electron-optical column 40.

[0164]

[0182] 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 in view of the specification and practices disclosed herein. This specification and examples are intended to be merely illustrative, and the true scope and spirit of the invention are shown by the following claims.

[0165]

[0183] The above description is intended to be an aid to understanding, not an limitation. Therefore, it will be apparent to those skilled in the art that modifications may be made as described without departing from the scope of the claims and clauses set forth below.

[0166]

[0184] Numerous clauses are provided.

[0167]

[0185] Clause 1: An electro-optical assembly for an electro-optical column for projecting a charged particle beam along a beam path toward a target, wherein the electro-optical assembly includes an electromagnetic shield configured to surround a charged particle beam path and shield the charged particle beam from an electromagnetic field outside the electromagnetic shield, the electromagnetic shield includes a plurality of sections extending along different locations along the beam path, each section surrounding a charged particle beam path, and the sections are separable.

[0168]

[0186] Clause 2: The electro-optical assembly described in Clause 1, wherein the sections are arranged such that a gap in the electromagnetic shield is formed between adjacent sections in the direction of the beam path.

[0169]

[0187] Clause 3: The electro-optical assembly according to Clause 2, wherein adjacent sections preferably have opposing surfaces that extend radially with respect to the beam path for a distance at least equal to the gap between adjacent sections.

[0170]

[0188] Clause 4: An electro-optical assembly as described in any of the preceding clauses, wherein at least one end of a section in the direction of the beam path includes a flange extending radially with respect to the beam path.

[0171]

[0189] Clause 5: An electro-optical assembly according to any one of the preceding clauses, comprising at least one electro-optical element between adjacent sections, preferably the electro-optical element comprising a plurality of manipulators, preferably a manipulator array.

[0172]

[0190] Clause 6: An electro-optical assembly as described in any of the preceding clauses, wherein the electromagnetic shield is configured to shield charged particle beams from an electric field.

[0173]

[0191] Clause 7: An electro-optical assembly as described in any of the preceding clauses, wherein the electromagnetic shield is configured to shield a charged particle beam from a magnetic field.

[0174]

[0192] Clause 8: An electro-optical assembly described in any of the preceding clauses, which includes a permeable material as an electromagnetic shield.

[0175]

[0193] Clause 9: An electro-optical assembly as described in any of the preceding clauses, wherein the sections are arranged such that at least one section is radially movable relative to the beam path, independently of any other section.

[0176]

[0194] Clause 10: An electro-optical assembly as described in any one of the preceding clauses, wherein at least two sections have adjacent ends that electromagnetically engage with each other.

[0177]

[0195] Clause 11: The electro-optical assembly described in Clause 10, wherein adjacent ends are sized to be coaxially aligned.

[0178]

[0196] Clause 12: An electro-optical column as described in Clause 10 or 11, wherein adjacent ends are sized to the required extent so that one end can be inserted into the other.

[0179]

[0197] Clause 13: An electro-optical column as described in any one of Clauses 10-12, wherein adjacent ends are physically separated and electrically engaged.

[0180]

[0198] Clause 14: The electro-optical assembly according to any one of the preceding claims, wherein at least one of the sections comprises a mechanical reference member configured to enable the position of the section to be determined.

[0181]

[0199] Clause 15: The electro-optical assembly according to claim 14, wherein a mechanical reference member is configured to mechanically engage with a corresponding mechanical reference member of another section or column.

[0182]

[0200] Clause 16: A module including an electro-optical assembly as described in any of the preceding clauses.

[0183]

[0201] Clause 17: A module comprising an electro-optical device and an electromagnetic shield for a beam path through the module when it is located in an electro-optical column for projecting a charged particle beam along the beam path toward a target, wherein the electromagnetic shield comprises an up-beam section of the up-beam of the electro-optical device and a down-beam section of the down-beam of the electro-optical device, and at least one of the up-beam section and the down-beam section has an interface that extends radially with respect to the beam path.

[0184]

[0202] Clause 18: The module as described in Clause 17, wherein the interface of the upbeam section forms an interface with the upbeam element of the column.

[0185]

[0203] Clause 19: The module according to Clause 18, wherein the up-beam element of the column includes an upper beam section of an electromagnetic shield, and the interface of the up-beam section is configured to be spaced apart such that a gap separates it from the upper beam section when the module is located within the electro-optical column, preferably the gap being at most the same size as the radial range of the interface of the up-beam section, and preferably at least one of the up-beam section and the down-beam section includes a flange extending radially with respect to the beam path.

[0186]

[0204] Clause 20: The module according to any one of Clauses 17 to 19, wherein the interface of the downbeam section forms an interface with the upbeam element of the column, and the interface of the upbeam interface is an opposing surface, preferably the interface provides a flange.

[0187]

[0205] Clause 21: The module according to Clause 20, wherein the down-beam element of the column includes a lower beam section of the electromagnetic shield, and the interface of the down-beam section is configured to be spaced apart such that a gap separates it from the lower beam section when the module is located within the electro-optical column, preferably the gap being at most the same size as the radial range of the interface of the down-beam section.

[0188]

[0206] Clause 22: A module described in any one of Clauses 17 to 21, wherein the electro-optical device is a MEMS device.

[0189]

[0207] Clause 23: A module that is a MEMS module, as described in any one of Clauses 16 to 22.

[0190]

[0208] Clause 24: A module as described in any one of Clauses 16 to 23, wherein the module is configured to be replaceable within an electro-optical column.

[0191]

[0209] Clause 25: A module as described in Clause 24, configured to be replaceable in the field.

[0192]

[0210] Clause 26: The module according to any one of claims 16 to 25, further comprising a mechanical reference member configured to enable the position of the module relative to the column to be determined when it is located within the electro-optical column.

[0193]

[0211] Clause 27: An electro-optical column including a module as described in any one of Clauses 16-25.

[0194]

[0212] Clause 28: An electro-optical column including an electro-optical assembly as described in any one of Clauses 1 to 15.

[0195]

[0213] Clause 29: An electron-optical column as described in Clause 27 or 28, wherein the electromagnetic shield is located radially inward of one or more electron-optical elements such as a thermal conditioner configured to thermally regulate at least a portion of the electron-optical column, a pump configured to reduce pressure within the electron-optical column, and a collimator configured to collimate a charged particle beam, or a deflector configured to deflect a charged particle beam.

[0196]

[0214] Clause 30: The electro-optical assembly described in Clause 29, wherein the thermal conditioner is configured to remove heat generated within the electro-optical column.

[0197]

[0215] Clause 31: An electron-optical column according to any one of claims 27 to 30, wherein at least one section radially surrounds at least one component selected from the group consisting of a charged particle source, a focusing lens, a collimator, a source converter, a deflector array, an aperture array, an aberration compensator array, an image-forming element array, an objective lens array, and a detector array.

[0198]

[0216] Clause 32: The electron-optical column according to claim 31, wherein the component is a MEMS component.

[0199]

[0217] Clause 33: The electron-optical column according to claim 31 or 32, wherein a section is arranged to be movable radially with respect to the beam path, independently of any other section, together with the components it surrounds.

[0200]

[0218] Clause 34: An electro-optical column according to any one of claims 31 to 33, wherein the section is replaceable in the field together with the components surrounding it.

[0201]

[0219] Clause 35: An apparatus comprising two or more electron-optical columns as described in any one of claims 31 to 34.

[0202]

[0220] Clause 36: The apparatus according to claim 35, wherein at least one section radially surrounds the beam paths of two or more of the electron-optical columns.

[0203]

[0221] Clause 37: The apparatus according to claim 35 or 36, wherein the beam path of at least one of the electron-optical columns is located radially outward of at least one section.

[0204]

[0222] Clause 38: The apparatus according to any one of claims 35 to 37, wherein at least one section radially surrounds the beam path of just one of the electron-optical columns.

[0205]

[0223] Clause 39: The apparatus according to any one of claims 35 to 38, wherein different sections of the electromagnetic shield radially surround the beam paths of each different electro-optical column, and the different sections are positioned to overlap in a direction parallel to the beam paths.

[0206]

[0224] Clause 40: The apparatus according to any one of claims 35 to 39, wherein multiple sections located in overlapping positions in a direction parallel to the beam path are arranged to be able to move together radially with respect to the beam path independently of any other section.

[0207]

[0225] Clause 41: A multi-column apparatus comprising: electron-optical columns configured to project respective charged particle beams along their respective beam paths toward a target; a charged particle source configured to generate charged particle beams for one or more of the electron-optical columns; and an electromagnetic shield surrounding the charged particle beam path of at least one of the electron-optical columns, wherein the electromagnetic shield comprises a plurality of sections extending along different locations along each beam path, each section surrounding a charged particle beam path, and the sections are separable.

[0208]

[0226] Clause 42: The multi-column apparatus according to claim 41, wherein the column is a multi-beam column configured to project respect multi-beams of charged particles toward a target along their respective beam paths.

[0209]

[0227] Clause 43: The multi-column apparatus according to claim 41 or 42, wherein the sections are arranged such that a gap in the electromagnetic shield is formed between adjacent sections in the direction of the beam path.

[0210]

[0228] Clause 44: The multi-column apparatus according to claim 43, wherein adjacent sections preferably have opposing surfaces extending radially with respect to the beam path for a distance at least equal to the gap between adjacent sections.

[0211]

[0229] Clause 45: The multi-column apparatus according to any one of claims 41 to 44, wherein the sections are arranged such that at least one section is radially movable relative to the beam path, independently of any other section.

[0212]

[0230] Clause 46: The multi-column apparatus according to any one of claims 41 to 45, wherein at least one of the sections comprises a mechanical reference member configured to enable the position of the section in a direction parallel to the beam path to be determined.

[0213]

[0231] Clause 47: A multi-column apparatus according to any one of claims 41 to 46, wherein at least one section radially surrounds at least one component selected from the group consisting of a charged particle source, a focusing lens array, a collimator array, a source converter, a deflector array, an aperture array, a corrector array, an aberration compensator array, an image-forming element array, an objective lens array, and a detector array.

[0214]

[0232] Clause 48: A multi-column apparatus according to any one of claims 41 to 47, wherein a section is arranged to be movable radially with respect to a beam path, independently of another section, together with the components it surrounds.

[0215]

[0233] Clause 49: A multi-column apparatus according to any one of claims 41 to 48, wherein at least one section radially surrounds the beam paths of two or more of the electron-optical columns.

[0216]

[0234] Clause 50: An electro-optical assembly for an electro-optical column for projecting a charged particle beam along a beam path toward a target, the electro-optical assembly comprising an electromagnetic shield configured to surround a charged particle beam path and shield the charged particle beam from an electromagnetic field outside the electromagnetic shield, the electromagnetic shield comprising a plurality of sections extending along and surrounding the beam path, at least two of the sections comprising adjacent ends that are separable and electromagnetically engage with each other.

[0217]

[0235] Clause 51: The electro-optical assembly described in Clause 50, in which each section specifies an aperture configured for the passage of a beam path.

[0218]

[0236] Clause 52: An electro-optical assembly as described in Clause 50 or 51, wherein multiple sections extend continuously along a beam path.

[0219]

[0237] Clause 53: A method for manufacturing an electro-optical assembly for an electro-optical column for projecting a charged particle beam along a beam path toward a target, the method comprising providing an electromagnetic shield to surround the charged particle beam and to shield the charged particle beam from an electromagnetic field outside the electromagnetic shield, wherein the electromagnetic shield comprises a plurality of sections extending along different locations along the beam path, each section surrounding the charged particle beam path, and the sections are separable.

[0220]

[0238] Clause 54: The method described in Clause 53, wherein the electro-optical assembly is included within the module.

[0221]

[0239] Clause 55: A method for replacing a module of an electron-optical column for projecting a charged particle beam along a beam path toward a target, the method comprising removing a module from an electron-optical column, the electron-optical column comprising an electromagnetic shield configured to surround a charged particle beam path and shield the charged particle beam from an electromagnetic field outside the electromagnetic shield, the electromagnetic shield comprising a plurality of sections extending along different locations along the beam path, each section surrounding a charged particle beam path, at least one of the sections being contained within a module and separable from other sections of the module's up-beam and / or down-beam sections.

[0222]

[0240] Clause 56: A method for projecting a charged particle beam along a beam path toward a target, the method comprising shielding the charged particle beam from an electromagnetic field outside an electromagnetic shield, wherein the electromagnetic shield comprises a plurality of sections extending along different locations along the beam path, each section surrounding the charged particle beam path, and the sections are separable.

[0223]

[0241] Clause 57: The method according to claim 56, comprising projecting a charged particle beam toward a target along the beam path of each electron-optical column.

[0224]

[0242] Clause 58: The method according to claim 57, wherein at least one section surrounds the beam paths of two or more electron-optical columns among the electron-optical columns and is positioned to be movable radially with respect to the beam paths, independently of another section, together with the one or more components it surrounds.

[0225]

[0243] Clause 59: The method according to claim 57 or 58, wherein different sections of the electromagnetic shield radially surround the beam path of each different electro-optical column, the different sections are in overlapping positions in a direction parallel to the beam path, and the different sections are arranged to be able to move together radially with respect to the beam path independently of any other section.

[0226]

[0244] Clause 60: A method for operating an electro-optical assembly configured to project a charged particle beam along a beam path toward a target, the assembly comprising a plurality of electromagnetic shielding sections configured to shield the charged particle beam from an electromagnetic field outside the electromagnetic shield, and an electro-optical device and a module configured to be removable from the assembly, wherein the method comprises removing the module from the assembly, and the removal comprises moving the sections of electromagnetic shielding within the module radially relative to the beam path.

[0227]

[0245] Clause 61: The method of Clause 60, further comprising replacing a module in an assembly, which includes moving a section of electromagnetic shielding within a module radially with respect to the beam path such that the section faces an adjacent section of electromagnetic shielding along the beam path within the assembly.

Claims

1. An electron-optical assembly for an electron-optical column for projecting a charged particle beam along a beam path toward a target, wherein the electron-optical assembly is The electromagnetic shield surrounds the charged particle beam path and shields the charged particle beam from electromagnetic fields outside the electromagnetic shield. Includes, The electromagnetic shield includes a plurality of sections extending along different locations along the beam path, each section surrounding the charged particle beam path. An electro-optical assembly in which the sections are separable, the sections are arranged such that a gap in the electromagnetic shield is formed in the direction of the beam path between at least two adjacent sections, the adjacent sections have opposing surfaces extending radially with respect to the beam path, and at least one of the opposing surfaces includes a flange extending radially with respect to the beam path.

2. The electron-optical assembly according to claim 2, wherein the opposing surface extends radially with respect to the beam path for a distance at least equal to the size of the gap between the adjacent sections.

3. The electro-optical assembly according to claim 1 or 2, comprising at least one electro-optical element between adjacent sections.

4. The electron-optical assembly according to claim 3, wherein the electron-optical element includes a plurality of manipulators, preferably a manipulator array.

5. The electro-optical assembly according to any one of claims 1 to 4, wherein the electromagnetic shield shields the charged particle beam from electric and / or magnetic fields.

6. The electro-optical assembly according to any one of claims 1 to 5, wherein the electromagnetic shield includes a magnetic permeable material.

7. The electro-optical assembly according to any one of claims 1 to 6, wherein the sections are arranged such that at least one section is radially movable relative to the beam path, independently of any other section.

8. The electro-optical assembly according to any one of claims 1 to 7, wherein at least two of the sections include adjacent ends that electromagnetically engage with each other.

9. The electro-optical assembly according to claim 8, wherein the adjacent ends are sized to be arranged coaxially.

10. The electro-optical assembly according to claim 8 or 9, wherein the adjacent ends are physically separated and electrically engaged.

11. The electro-optical assembly according to any one of claims 1 to 10, wherein at least one of the sections comprises a mechanical reference member that enables the position of the section to be determined.

12. The electro-optical assembly according to claim 11, wherein the mechanical reference member mechanically engages with another mechanical reference member of the section or the corresponding mechanical reference member of the column.

13. A module comprising an electro-optical device and an electromagnetic shield for the beam path through the module when it is located in an electro-optical column for projecting a charged particle beam along the beam path toward a target, wherein the electromagnetic shield comprises an up-beam section of the up-beam of the electro-optical device and a down-beam section of the down-beam of the electro-optical device, wherein at least one of the up-beam section and the down-beam section has an interface extending radially with respect to the beam path, and at least one of the up-beam section and the down-beam section includes a flange extending radially with respect to the beam path.

14. The module according to claim 13, wherein the interface of the upbeam section forms an interface with the upbeam element of the column, and the interface of the upbeam interface is an opposing surface.

15. The module according to claim 14, wherein the up-beam element of the column includes the upper beam section of the electromagnetic shield, and the interface of the up-beam section is spaced apart from the upper beam section by a gap when the module is located within the electro-optical column, preferably the gap being at most the same size as the radius range of the interface of the up-beam section.

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