Electrooptical assembly

Abstract

A charged particle optical assembly configured to direct a plurality of charged particle beams in a beam grid to a sample location, the charged particle optical assembly comprising: a planar charged particle optical element configured to operate on the charged particle beams of the beam grid at a voltage, the charged particle optical element includes a plurality of apertures for paths of different beams of the beam grid; an electrical conductor electrically connected to the charged particle optical element, where a recess is defined within the electrical conductor configured to provide a field-free volume for insertion of an electrical coupler to electrically connect the charged particle optical element with a power source through the electrical coupler; and an electrical insulator covering at least a portion of a surface of the electrical conductor, the surface facing away from the charged particle optical element.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to EP application 22184926.8 filed on July 14, 2022, and the entire contents of which are incorporated herein by reference. Technical Field

[0003] Embodiments provided herein generally relate to charged particle optical components, charged particle optical devices, charged particle optical apparatuses, and methods for providing electrical connections and methods for electrically insulating electrical conductors of charged particle optical components. Background Art

[0004] When manufacturing semiconductor integrated circuit (IC) chips, undesirable pattern defects may appear on the substrate (e.g., wafer) or mask during the manufacturing process, thereby reducing the yield. Defects may be caused by optical effects and accidental particles or other processing steps (e.g., etching, chemical mechanical polishing deposition). Therefore, monitoring the degree of undesirable pattern defects is an important process in IC chip manufacturing. More generally, inspecting and / or measuring the surface of a substrate or other object / material is an important process during and / or after its manufacturing process.

[0005] Pattern inspection tools with charged particle beams have been used to inspect objects, such as detecting pattern defects. These tools typically use electron microscopy techniques, such as scanning electron microscopes (SEMs). In an SEM, a relatively high energy electron beam is targeted at a final deceleration step so that it lands on the target with a relatively low landing energy. The electron beam is focused to a probe point on the target. The interaction between the material structure at the probe point and the landing electrons of the electron beam causes electrons to be emitted from the surface, such as secondary electrons, backscattered electrons, or Auger electrons, which are collectively referred to as signal electrons or more generally as signal particles. The secondary electrons generated can be emitted from the material structure of the target.

[0006] The primary electron beam is scanned on the target surface as a detection point, and secondary electrons may be emitted across the target surface. By collecting these secondary electrons emitted from the target surface, the pattern inspection tool (or device) can obtain an image-like signal representing the structural characteristics of the target surface material. In this inspection, the collected secondary electrons are detected by a detector within the device. The detector generates a signal in response to an accidental particle. When an area of ​​the sample is inspected, the signal includes data that is processed to generate an inspection image corresponding to the inspected area of ​​the sample. The image may contain pixels. Each pixel may correspond to a portion of the inspected area. Typically, an electron beam inspection device has a single beam, which may be referred to as a single-beam SEM. Attempts have been made to introduce multi-electron beam inspection in a device (or "multi-beam tool"), which may be referred to as a multi-beam SEM (MBSEM).

[0007] Another application of electron optical devices (or devices or arrays of devices) is photolithography. A beam of charged particles reacts with a resist layer on the surface of a substrate. By controlling where the charged particle beam is directed on the resist layer, a desired pattern can be created in the resist.

[0008] Electron-optical devices can be devices used to generate, illuminate, project and / or detect one or more beams of charged particles. The path of the charged particle beam is controlled by electromagnetic fields (i.e., electrostatic and magnetic fields). Stray electromagnetic fields may unnecessarily steer the particle beam.

[0009] In some electro-optical devices, an electrostatic field is usually generated between two electrodes. A high voltage needs to be applied to the electrodes. Undesirable electronic creepage and therefore undesirable discharges may occur, for example between high-voltage connectors and / or between high-voltage connectors and electro-optical components of the electro-optical device. Summary of the invention

[0010] The present invention provides suitable structures to achieve the required high voltage connection while reducing the risk of electronic creepage. According to a first aspect of the present invention, a charged particle optical component is provided, which is configured to guide a charged particle beam along a beam path to a sample position, the charged particle optical component comprising: a planar charged particle optical element, which is configured to operate on the charged particle beam along the beam path toward the sample position, the charged particle optical element comprising an aperture for the beam path; and an electrical conductor, which is electrically connected to the charged particle optical element, wherein a groove is defined in the electrical conductor and is configured to provide a field-free volume for inserting a high voltage cable, the high voltage cable being used to electrically connect the charged particle optical element to a power supply through an electrical coupler; wherein the electrical conductor comprises an electrical insulator, which is spaced apart from the planar charged particle optical element and provides at least a portion of the surface of the electrical conductor.

[0011] According to a second aspect of the present invention, a charged particle optical component is provided, which is configured to guide multiple charged particle beams along a beam path to a sample position, the charged particle optical component comprising: a planar charged particle optical element, which is configured to operate on the charged particle beam along the beam path toward the sample position, the charged particle optical element comprising an aperture for the beam path; and a conductor, which is electrically connected to the charged particle optical element, wherein a groove is defined in the conductor, and the groove is configured to provide a field-free volume for inserting a high-voltage cable, the high-voltage cable being used to electrically connect the charged particle optical element to a power supply via an electrical coupler; wherein the electrical insulator covers at least a portion of a surface of the conductor, which surface faces away from the charged particle optical element.

[0012] According to a third aspect of the invention, a method for electrically insulating a conductor of a charged particle optical component is provided, wherein the conductor is configured to direct a charged particle beam toward a sample position, the method comprising: covering at least a portion of a surface of the conductor with one or more electrical insulators, the surface facing away from a planar charged particle optical element electrically connected to the conductor, the charged particle optical element being configured to operate a charged particle beam along a beam path and including an aperture for the beam path, wherein a groove is defined within the conductor and the groove is configured to provide a field-free volume for inserting a high-voltage cable, the high-voltage cable being used to electrically connect the charged particle optical element to a power source via an electrical coupler.

[0013] According to a fourth aspect of the present invention, a method for electrically insulating a conductor of a charged particle optical component is provided, the charged particle optical component being configured to direct a charged particle beam along a beam path to a sample position, the charged particle optical component comprising a planar charged particle optical element for operating the charged particle beam, the method comprising: having a conductor, a groove of the conductor having a conductive concave surface, the conductor comprising an electrical insulator spaced apart from the planar charged particle optical element, the planar charged particle optical element being electrically connected to the conductor, wherein the groove is configured in the conductor to provide a field-free volume for inserting a high-voltage cable, the high-voltage cable being used to electrically connect the charged particle optical element to a power source via an electrical coupler between the conductor and the high-voltage cable.

[0014] According to a fifth aspect of the present invention, a charged particle optical component is provided, which is configured to guide multiple charged particle beams along a beam path to a sample position, the charged particle optical component comprising: a planar charged particle optical element, which is configured to operate the charged particle beam along the beam path toward the sample with a voltage, the charged particle optical element comprising an aperture for the beam path; and a conductor, which is electrically connected to the charged particle optical element, wherein a groove is defined in the conductor, and the groove is configured to provide a field-free volume for inserting a high-voltage cable, the high-voltage cable being used to electrically connect the charged particle optical element to a power source through an electrical coupler; wherein the conductor comprises an electrical insulator, the electrical insulator comprising at least an end face of the conductor and an extended surface extending from the end face into the groove.

[0015] Advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which certain embodiments of the invention are set forth by way of illustration and example. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other aspects of the present disclosure will become more apparent through the description of exemplary embodiments with reference to the attached drawings.

[0017] Figure 1 is a schematic diagram illustrating an exemplary electron beam inspection apparatus.

[0018] Figure 2 is shown as Figure 1 A schematic diagram of an exemplary multi-beam electron optical device that is a portion of an exemplary electron beam inspection apparatus.

[0019] Figure 3 is a schematic diagram of an exemplary electron-optical device including an array of collimator elements and an array of scanning deflectors, the electron-optical device being Figure 1 A portion of an exemplary electron beam inspection apparatus.

[0020] Figure 4 Yes Figure 3 Schematic diagram of an exemplary electron-optical device array of electron-optical devices.

[0021] Figure 5 As Figure 1 A schematic diagram of an alternative exemplary electron optical device of a portion of an exemplary electron beam inspection apparatus.

[0022] Figure 6 yes Figure 3 , Figure 4 and Figure 5 Schematic diagram of an exemplary electron-optical assembly of a portion of an electron-optical device.

[0023] Figure 7 is a schematic diagram of an electron optical component electrically connected to a cable.

[0024] Figure 8 is a schematic diagram of an electron optical component electrically connected to a cable.

[0025] Fig. 9 is a plan view of the electron optical assembly.

[0026] Fig.10 is a plan view of the electron optical assembly.

[0027] Fig.11 is a plan view of the electron optical assembly.

[0028] Reference will now be made in detail to exemplary embodiments, examples of which are shown in the accompanying drawings. The following description refers to the accompanying drawings, wherein the same numbers in different figures represent the same or similar elements unless otherwise specified. The implementations set forth in the following description of exemplary embodiments do not represent all implementations consistent with the present invention. Instead, they are merely examples of devices and methods consistent with aspects related to the present invention as described in the appended claims. DETAILED DESCRIPTION

[0029] The reduction in physical size of devices and the increase in computing power of electronic devices can be achieved by significantly increasing the packing density of circuit elements such as transistors, capacitors, diodes, etc. on IC chips. This is achieved by the increased resolution that enables the manufacture of smaller structures. Semiconductor IC manufacturing is a complex and time-consuming process involving hundreds of individual steps. Errors in any step in the process of manufacturing IC chips have the potential to adversely affect the functionality of the final product. Just one defect can cause device failure. It is desirable to increase the yield of the entire process. For example, to achieve a 75% yield for a 50-step process (where a step may represent the number of layers formed on a wafer), the yield of each individual step must be greater than 99.4%. If the yield of a single step is 95%, the yield of the entire process will be as low as 7-8%.

[0030] Maintaining high substrate (i.e., wafer) throughput (defined as the number of substrates processed per hour) is also desirable. High process yield and high substrate throughput may be affected by the presence of defects. This is especially true if operator intervention is required to detect the defect. High throughput detection and identification of micro- and nano-scale defects by inspection systems such as scanning electron microscopes ("SEMs") is ideal for maintaining high yield and low cost of IC chips.

[0031] The scanning electron microscope comprises a scanning device and a detector device. The scanning device comprises an irradiation device, the irradiation device comprises an electron source for generating primary electrons, and a projection device for scanning a target (e.g., a substrate) using one or more focused primary electron beams. The primary electrons interact with the target and produce interaction products, such as signal particles (e.g., secondary electrons and / or backscattered electrons). The secondary electrons can be considered to have an energy of up to 50 eV. Although the backscattered electrons have an energy spectrum from substantially zero to the maximum energy of the charged particle device, they are generally set to electrons (or signal electrons) with an energy of more than 50 eV. The detection device captures signal particles (e.g., secondary electrons and / or backscattered electrons) from the target while scanning the target, so that the scanning electron microscope can create an image of the scanned area of ​​the target. The design of the electron optical device that embodies these scanning electron microscope features can have a single beam. In order to achieve higher throughput (e.g., for inspection), the design of some devices uses multiple focused beams, i.e., multiple beams of primary electrons. The component beams of the multiple beams can be referred to as sub-beams or sub-beams. Multiple beams can scan different parts of the target simultaneously. Thus, a multi-beam inspection device can inspect an object more quickly than a single-beam inspection device, for example, by moving the object at a higher speed.

[0032] In a multi-beam inspection device, the paths of some primary electron beams deviate 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). In order to ensure that all electron beams arrive at the sample surface at substantially the same angle of incidence, it is necessary to manipulate the sub-beam paths with a larger radial distance from the central axis so that they move at a larger angle than the sub-beam paths with paths closer to the central axis. This stronger manipulation may cause aberrations, resulting in blurring and defocusing of the generated image. An example is spherical aberration, which brings the focus of each sub-beam path into a different focal plane. In particular, for sub-beam paths that are not on the central axis, the change in the focal plane in the sub-beam is greater as the radial displacement from the central axis increases. Such aberrations and defocusing effects may be associated with signal particles (e.g., secondary electrons) from the target when they are detected, for example, the shape and size of the spot formed by the sub-beam on the target will be affected. Therefore, such aberrations reduce the quality of the image produced during the inspection.

[0033] The following describes the implementation of a known multi-beam inspection device.

[0034] The drawings are schematic. Therefore, for the sake of clarity, the relative sizes of the components in the figures are exaggerated. 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 related to the various embodiments are described. Although the description and drawings are directed to electron-optical devices, it should be understood that the embodiments are not intended to limit the present disclosure to specific charged particles. Therefore, references to electrons and items mentioned with reference to electrons throughout this document can be more generally considered as references to charged particles, and items mentioned with reference to charged particles, where the charged particles are not necessarily electrons.

[0035] Reference now Figure 1 , which is a schematic diagram illustrating an exemplary electron beam evaluation apparatus or inspection apparatus 100 . Figure 1 The inspection apparatus 100 includes a vacuum chamber 10, a load lock chamber 20, an electron optical device, an equipment front end module (EFEM) 30, and a controller 50. The electron optical device 40 may be located in the vacuum chamber 10. The electron optical device may include the electron optical device 40 (also referred to as an electron optical device, an electron beam device, or an electron beam device) and a motorized or actuated stage.

[0036] The EFEM 30 includes a first loading port 30a and a second loading port 30b. The EFEM 30 may include additional loading ports (multiple). The first loading port 30a and the second loading port 30b may, for example, receive a substrate front opening pod (FOUP) containing a substrate (e.g., a semiconductor substrate or a substrate made of other materials) or an object to be inspected (substrates, wafers, and samples are collectively referred to as "objects" hereinafter). One or more robotic arms (not shown) in the EFEM 30 transfer the object to the load lock chamber 20.

[0037] The load lock chamber 20 is used to remove gas around the target. The load lock chamber 20 can be connected to a load lock vacuum pump system (not shown), which removes gas particles in the load lock chamber 20. The operation of the load lock vacuum pump system causes the load lock chamber to reach a first pressure lower than atmospheric pressure. The main chamber 10 is connected to the main chamber vacuum pump system (not shown). The main chamber vacuum pump system removes gas molecules in the main chamber 10 so that the pressure around the target reaches a second pressure lower than the first pressure. After reaching the second pressure, the target is transferred to the electron optical device 40, through which it can be inspected. The electron optical device 40 may include a single beam electron optical device or a multi-beam electron optical device.

[0038] The controller 50 is electronically connected to the electron optical device 40. The controller 50 may be a processor (eg, a computer) configured to control the charged particle beam inspection apparatus 100. The controller 50 may also include processing circuitry configured to perform various signal and image processing functions. Figure 1 The controller 50 is shown as being located outside the structure including the main chamber 10, the load lock chamber 20 and the EFEM 30, but it is understood that the controller 50 can be part of the structure. The controller 50 can be located in one of the constituent elements of the charged particle beam inspection device, or can be distributed on at least two constituent elements. Although the present disclosure provides an example of a main chamber 10 that accommodates an electron beam inspection device, it should be noted that the aspects of the present disclosure are not limited to chambers that accommodate electron optical devices in their broadest sense. On the contrary, it is understood that the aforementioned principles can also be applied to other devices and other equipment arrangements that operate at a second pressure.

[0039] Reference now Figure 2 , which is an evaluation device (e.g., Figure 1Schematic diagram of an exemplary multi-beam electron optical device 40 of an evaluation device 100 of a single beam inspection device. In an alternative embodiment, the inspection device 100 is a single beam inspection device. The electron optical device 40 may include an electron source 201, a beam former array 372 (also known as a gun aperture plate, a Coulomb aperture array, or a pre-sub-beam forming aperture array), a converging lens 310, a source converter (or micro-optical array) 320, an objective lens 331, and a target 308. In one embodiment, the converging lens 310 is magnetic. (The single beam evaluation device may have the same features as the multi-beam evaluation device, except that the electron optical component having the array apertures 372, 320 may have a single aperture. The source converter 320 may be replaced by multiple electron optical components along the beam path). 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 the incident electrons. The electron source 201, the beam former array 372, and the focusing lens 310 may be components of an irradiation device included in the electron optical device 40. The source converter 320 (also referred to as a source conversion unit) (described in more detail below) and the objective lens 331 may be components of a projection device included in the electron optical device 40.

[0040] The electron source 201, the beam former array 372, the converging lens 310, the source converter 320 and the objective lens 331 are aligned with the primary electron optical axis 304 of the electron optical device 40. The electron source 201 can generate a primary beam 302, which is substantially along the electron optical axis 304 and has a source crossover voltage (virtual or real) 301S. During operation, the electron source 201 is configured to emit electrons. The electrons are extracted or accelerated by the extractor and / or the anode to form the primary beam 302.

[0041] The beam former array 372 cuts off peripheral electrons of the primary electron beam 302 to reduce the ensuing Coulomb effect. The beam former array 372 can trim the primary electron beam 302 into a specified number of sub-beams, such as three sub-beams 311, 312, and 313. It should be understood that the description is intended to apply to an electron optical device 40 having any number of sub-beams (e.g., one, two, or more than three). The beam former array 372 is configured to block peripheral electrons in operation to reduce the Coulomb effect. The Coulomb effect may enlarge the size of each detection point 391, 392, 393, thereby reducing the inspection resolution. The beam former array 372 reduces aberrations caused by the Coulomb interaction between the electrons projected into the beam. The beam former array 372 may even include multiple openings for generating primary sub-beams before the source converter 320.

[0042] Source converter 320 is configured to convert the beam (including beamlets, if any) transmitted by beamformer array 372 into beamlets that are projected onto target 308. In one embodiment, source converter is a unit. Alternatively, the term source converter may simply be used as a collective term for a group of components that form a beamlet from a beamlet.

[0043] like Figure 2 As shown, in one embodiment, the electron optical device 40 includes a beam limiting aperture array 321, whose aperture pattern (i.e., apertures arranged in a certain form) is configured to limit the outer dimensions of a beamlet (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 an alternative embodiment, the beam limiting aperture array 321 is part of an upstream system of the host device. In one embodiment, the beam limiting aperture array 321 divides one or more sub-beams 311, 312, 313 into sub-beams, so that the number of beamlets projected toward the target 308 is greater than the number of beamlets transmitted through the beam former array 372. In an alternative embodiment, the beam limiting aperture array 321 maintains the number of beamlets incident on the beam limiting aperture array 321, in which case the number of beamlets can be equal to the number of beamlets projected toward the target 308.

[0044] like Figure 2 As shown, in one embodiment, the electron optical device 40 includes a pre-bending deflector array 323 having pre-bending deflectors 323_1, 323_2 and 323_3 to respectively bend sub-beams 311, 312 and 313. 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.

[0045] The electron optical device 40 may also include an image forming element array 322 having image forming deflectors 322_1, 322_2 and 322_3. The path of each sub-beam has a corresponding deflector 322_1, 322_2 and 322_3. Deflectors 322_1, 322_2 and 322_3 are configured to deflect the path of the sub-beam toward the electron optical axis 304. The deflected sub-beams form a virtual image (not shown) of the source intersection 301S. In the current embodiment, these virtual images are projected onto the target 308 by the objective lens 331 and form detection points 391, 392, 393 located thereon. The electron optical device 40 may also include an aberration compensator array 324, which is configured to compensate for the aberrations that may exist in each sub-beam. In one embodiment, the aberration compensator array 324 includes a lens configured to operate on the corresponding sub-beam. The lens may be in the form of a lens array. The lenses in the array may operate on different sub-beams of the multi-beam. The aberration compensator array 324 may, for example, include a field curvature compensator array (not shown) having microlenses. The field curvature compensator and the microlenses may, for example, be configured to compensate for the field curvature aberrations of the respective sub-beams that are evident in the detection points 391, 392, and 393. The aberration compensator array 324 may include an astigmatism compensator array (not shown) having micro-stigmatizers. For example, the micro-stigmatizers may be controlled to operate the sub-beams to compensate for the astigmatism aberrations present in the detection points 391, 392, and 393.

[0046] The source converter 320 may be the electron optical assembly 700 described herein. The source converter 320 may include a pre-bending deflector array 323, a beam-limiting aperture array 321, an aberration compensator array 324, and an image forming element array 322. The pre-bending deflector array 323 may include pre-bending deflectors 323_1, 323_2, and 323_3 to bend the sub-beams 311, 312, and 313, respectively. The pre-bending deflectors 323_1, 323_2, and 323_3 may bend the paths of the sub-beams onto the beam-limiting aperture array 321. In one embodiment, the pre-bending micro-deflector array 323 may be configured to bend the sub-beam paths of the sub-beams to an orthogonal direction of the plane of the beam-limiting aperture array 321. In an alternative embodiment, the converging lens 310 may adjust the paths of the sub-beams onto the beam-limiting aperture array 321. The converging lens 310 may, for example, focus (collimate) the three sub-beams 311, 312, and 313 into substantially parallel beams along the primary electron optical axis 304, such that the three sub-beams 311, 312, and 313 are substantially perpendicularly incident on the source converter 320, which may correspond to the beam-limiting aperture array 321. In such an alternative embodiment, the pre-bend deflector array 323 may not be necessary.

[0047] The image forming element array 322, the aberration compensator array 324 and the pre-bent deflector array 323 may include multiple layers of beamlet steering devices, some of which may be in array form, such as microdeflectors, microlenses or micro-stigmators. The beam path may be rotationally steered. Rotational correction may be applied via magnetic lenses. Rotational correction may be additionally or alternatively achieved via existing magnetic lenses, such as a converging lens arrangement.

[0048] In the present example of the electron optical device 40, the sub-beams are respectively deflected by deflectors 322_1, 322_2 and 322_3 of the image forming element array 322 to the electron optical axis 304. It should be understood that the sub-beam paths may already correspond to the electron optical axis 304 before reaching the deflectors 322_1, 322_2 and 322_3.

[0049] The objective lens 331 focuses the beamlets onto the surface of the target 308, i.e., projects three virtual images onto the target surface. The three images 313 formed by the three beamlets 311 form three detection points 391, 392, and 393 on the target surface. In one embodiment, the deflection angles of the beamlets 311 to 313 are adjusted to pass through or approach the front focus of the objective lens 331 to reduce or limit the off-axis aberrations of the three detection points 391 to 393. In the arrangement, the objective lens 331 is magnetic. Although three beamlets are mentioned, this is only an example. There can be any number of beamlets.

[0050] The manipulator is configured to manipulate one or more charged particle beams. The term manipulator includes a deflector, a lens, and an aperture. The pre-bent deflector array 323, the aberration compensator array 324, and the image forming element array 322 can be referred to as a manipulator array individually or in combination with each other because they manipulate one or more sub-beams or beamlets of charged particles. Lenses and deflectors 322_1, 322_2, and 322_3 can be referred to as manipulators because they manipulate one or more sub-beams or beamlets of charged particles.

[0051] In one embodiment, a beam splitter (not shown) is provided. The beam splitter may be located downstream of the source converter 320. The beam splitter may be, for example, a Wien filter including an electrostatic dipole field and a magnetic dipole field. The beam splitter may be located upstream of the objective lens 331. The beam splitter may be positioned between adjacent portions of the shield in the direction of the beam path. The inner surface of the shield may be located radially inward of the beam splitter. Alternatively, the beam splitter may be located within the shield. In operation, the beam splitter may be configured to apply an electrostatic force to a single electron of a sub-beam through an electrostatic dipole field. In one embodiment, the magnitude of the electrostatic force is equal to but opposite in direction to the magnetic force applied by the magnetic dipole field of the beam splitter to a single primary electron of the sub-beam. Therefore, the sub-beam may pass through the beam splitter at least substantially straight, with a deflection angle of at least substantially zero. The direction of the magnetic force depends on the direction of motion of the electron, while the direction of the electrostatic force does not depend on the direction of motion of the electron. Therefore, since secondary electrons and backscattered electrons (or signal electrons) generally move in the opposite direction to primary electrons, the magnetic force applied to the secondary electrons and backscattered electrons (or signal particles) will no longer offset the electrostatic force, and therefore, the secondary electrons and backscattered electrons passing through the beam splitter will deviate from the electron optical axis 304.

[0052] In one embodiment, a secondary device (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 an array, which may be in the form of a grid. The array may have one or more pixels; each pixel may correspond to an element of the array. The intensity signal output of the detection element may be the sum of the signals generated by all pixels in the detection element.

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

[0054] Such Wien filter, secondary device and / or secondary projection device can be provided in a single beam evaluation device. In addition and / or alternatively, there can be a detection device downstream of the objective lens, such as facing the sample during operation. In an alternative arrangement, the detector device is positioned along the path of the charged particle beam towards the sample. This arrangement does not have a Wien filter, a secondary device and a secondary projection device. The detection device can be positioned at one or more positions along the path of the charged particle beam towards the sample, such as facing the sample during operation, such as around the path of the charged particle beam. Such a detector device can have an aperture and can be annular. Different detector devices can be positioned along the path of the charged particles to detect signal particles with different characteristics. The electron optical element along the charged particle beam path can include one or more electrostatic plates with an aperture for the charged particle beam path, which can be arranged and controlled to focus the signal particles with different corresponding characteristics to the corresponding detector devices at different positions along the charged particle beam path. Such electrostatic plates can be arranged into a series of two or more adjacent plates along the path of the charged particle beam.

[0055] In one embodiment, inspection apparatus 100 includes a single source.

[0056] Any element or collection of elements within the electron-optical device may be replaced or field-replaced. One or more electron-optical components in the electron-optical device, especially those that operate on or generate beamlets, such as aperture arrays and manipulator arrays, may include one or more micro-electromechanical systems (MEMS). The pre-bent deflector array 323 may be a MEMS. MEMS are micro-mechanical and electromechanical components manufactured using micromachining techniques. In one embodiment, the electron-optical device 40 includes an aperture, a lens, and a deflector formed as a MEMS. In one embodiment, the manipulators (such as lenses and deflectors 322_1, 322_2, and 322_3) may be controlled passively, actively, as an entire array, individually, or in groups within an array to control the charged particle beam projected toward the target 308.

[0057] In one embodiment, the electron optical device 40 may include alternative and / or additional components in the charged particle path, such as lenses and other components, some of which have been previously described with reference to Figure 1 and Figure 2 An example of such an arrangement is Figure 3 and Figure 4As shown, it will be described in more detail later. Specifically, an embodiment includes an electron optical device 40, which divides the charged particle beam from the source into a plurality of sub-beams. A plurality of corresponding objective lenses can project the sub-beams onto the sample. In some embodiments, a plurality of converging lenses are arranged upstream of the objective lens. The converging lens focuses each sub-beam to an intermediate focus upstream of the objective lens. In some embodiments, a collimator is arranged upstream of the objective lens. A corrector can be provided to reduce focusing errors and / or aberrations. In some embodiments, such a corrector is integrated into the objective lens or positioned directly adjacent to the objective lens. When a converging lens is provided, such a corrector can be additionally or alternatively integrated into the converging lens or positioned directly near the converging lens and / or positioned in the intermediate focus or positioned directly near the intermediate focus. A detector is provided to detect the charged particles emitted by the sample. The detector can be integrated into the objective lens. The detector can be located on the bottom surface of the objective lens so as to face the sample in use. The detector can include an array of sub-beam arrays that can correspond to a multi-beam arrangement. The detector in the detector array can generate a detection signal that can be associated with a pixel of the generated image. The converging lens, the objective lens and / or the detector may be formed as MEMS or CMOS devices.

[0058] Figure 3 is a schematic diagram of another design of an exemplary electron-optical device 40. The electron-optical device 40 may include a source 201 and one or more electron-optical components. Alternatively, an electron-optical device including the electron-optical device 40 may include the source 201. The electron-optical device 40 may include an upper beam limiter 252, a collimator element array 271, a control lens array 250, a scanning deflector array 260, an objective lens array 241, a beam shaping limiter 242, and a detector array. The source 201 provides a charged particle beam (e.g., electrons). The multiple beams focused on the sample 208 come from the beam provided by the source 201. Sub-beams can be obtained from the beam, for example, using a beam limiter that defines an array of beam-limiting apertures. The source 201 is preferably a high-brightness thermal field emitter that has a good compromise between brightness and total emission current.

[0059] The upper beam limiter 252 defines a beam limiting aperture array. The upper beam limiter 252 may be referred to as an upper beam limiting aperture array or an upstream beam limiting aperture array. The upper beam limiter 252 may include a plate (which may be a plate-shaped body) having a plurality of apertures. The upper beam limiter 252 forms sub-beams from the charged particle beam emitted by the source 201. Portions of the beam other than those that contribute to forming the sub-beams may be blocked (e.g., absorbed) by the upper beam limiter 252 so as not to interfere with downstream sub-beams. The upper beam limiter 252 may be referred to as a sub-beam limiting aperture array.

[0060] The collimator element array 271 is disposed downstream of the upper beam limiter. Each collimator element collimates a corresponding sub-beam. The collimator element array 271 can be formed using MEMS manufacturing technology, thereby being compact in space. In some embodiments, as shown in FIG. Figure 3 As shown, the collimator element array 271 is the first deflection or focusing electron optical array element in the downstream path of the source 201. In another arrangement, the collimator can be in the form of a macro-collimator in whole or in part. Such a macro-collimator can be located upstream of the upper beam limiter 252 so that it operates on the beam from the source before generating multiple beams. A magnetic lens can be used as a macro-collimator.

[0061] Downstream of the collimator element array is a control lens array 250. 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 a corresponding potential source. The control lens array 250 may include two or more (e.g., three) plate electrode arrays connected to a corresponding potential source. The control lens array 250 is associated with the objective lens array 241 (e.g., the two arrays are close to each other and / or mechanically connected and / or controlled together as a unit). The control lens array 250 is located upstream of the objective lens array 241. The control lenses pre-focus the sub-beams (e.g., apply a focusing action to the sub-beams before the sub-beams reach the objective lens array 241). Pre-focusing can reduce the divergence of the sub-beams or increase the convergence rate of the sub-beams. Although the control lens array 241 may be indistinguishable from the objective lens array 250 and is part of the objective lens array 250, in this description, the control lens array 250 is considered to be different and separate from the objective lens array 241.

[0062] As mentioned above, the control lens array 250 is associated with the objective lens array 241. As mentioned above, the control lens array 250 can be regarded as providing electrodes additional to the electrodes 242, 243 of the objective lens array 241, for example as part of the objective lens array assembly. The additional electrodes of the control lens array 250 allow additional degrees of freedom to control the electron optical parameters of the sub-beams. In one embodiment, the control lens array 250 can be regarded as additional electrodes of the objective lens array 241, thereby realizing additional functions of the corresponding objective lenses of the objective lens array 241. In one arrangement, such electrodes can be regarded as part of the objective lens array, providing additional functions for the objective lenses of the objective lens array 241. In this arrangement, the control lens is regarded as part of the corresponding objective lens, or even to some extent, the control lens is only referred to as a part of the objective lens, for example in terms of providing more additional degrees of freedom for the objective lens.

[0063] For ease of illustration, the lens array is schematically shown here as an array of ellipses. Each ellipse represents a lens in the lens array. Ellipses are often used to represent lenses, similar to the biconvex shapes often used in optical lenses. However, in the context of charged particle arrangements (such as the arrangements discussed herein), it should be understood that lens arrays are typically operated electrostatically, and therefore any physical elements that use biconvex shapes may not be required. As described above, the lens array can instead include multiple plates with apertures.

[0064] A scanning deflector array 260 including a plurality of scanning deflectors may be provided. The scanning deflector array 260 may be formed using MEMS manufacturing techniques. Each scanning deflector scans a corresponding sub-beam on the sample 208. Thus, the scanning deflector array 260 may include a scanning deflector for each sub-beam. Each scanning deflector may deflect the sub-beam into one direction (e.g., parallel to a single axis, such as the X-axis) or two directions (e.g., relative to two non-parallel axes, such as the X-axis and the Y-axis). The deflection causes the sub-beam to be scanned across the sample 208 in one or two directions (i.e., one dimension or two dimensions). In one embodiment, the scanning deflector described in EP2425444 may be used to implement the scanning deflector array 260, which document is hereby incorporated by reference in its entirety, particularly with respect to the portion regarding the scanning deflector. The scanning deflector array 260 (e.g., formed using MEMS manufacturing techniques as described above) may be more compact in space than a macro scanning deflector. In another arrangement, a macro scanning deflector may be used upstream of the upper beam limiter 252. Its function may be similar or identical to that of a scanning deflector array, although it operates on beams from the source prior to the generation of beamlets of a multi-beam.

[0065] The objective lens array 241 includes a plurality of objective lenses for directing sub-beams onto the sample 208. Each objective lens includes at least two electrodes (e.g., two or three electrodes) connected to corresponding potential sources. The objective lens array 241 may include two or more (e.g., three) plate electrode arrays connected to corresponding potential sources. Each objective lens formed by the plate electrode array may be a microlens that operates on different sub-beams. Each plate defines a plurality of apertures (also referred to as holes). The position of each aperture in the plate corresponds to the position of a corresponding aperture (or multiple apertures) in another plate (or multiple plates). The corresponding apertures define the objective lens, so that each group of corresponding apertures operates on the same sub-beam in the multi-beam during use. Each objective lens projects a corresponding sub-beam of the multi-beam onto the sample 208.

[0066] The aberration of an objective lens array 241 having only two electrodes can be smaller than an objective lens array 241 having more electrodes. The potential difference between the electrodes of a three-electrode objective lens can be larger, thereby enabling a stronger lens. Additional electrodes (i.e., more than two electrodes) provide additional degrees of freedom to control electron trajectories, such as focusing secondary electrons as well as the incident beam. Such additional electrodes can be considered to form a control lens array 250. The advantage of a two-electrode lens over an Einzel lens is that the energy of the incident beam is not necessarily the same as the outgoing beam. Advantageously, the potential difference on such a two-electrode lens array enables it to be used as an acceleration or deceleration lens array.

[0067] The objective lens array may form part of an objective lens array assembly together with any one or all of the scanning deflector array 260, the control lens array 250, and the collimator element array 271. The objective lens array assembly may also include a beam shaping limiter 242. The beam shaping limiter 242 defines a beam limiting aperture array. The beam shaping limiter 242 may be referred to as a lower beam limiter, a lower beam limiting aperture array, or a final beam limiting aperture array. The beam shaping limiter 242 may include a plate (which may be a plate-shaped body) having a plurality of apertures. The beam shaping limiter 242 is downstream of at least one electrode (optionally all electrodes) of the control lens array 250. In some embodiments, the beam shaping limiter 242 is located downstream of at least one electrode (optionally from all electrodes) of the objective lens array 241.

[0068] In one arrangement, the beam shaping limiter 242 is structurally integrated with the electrode 302 of the objective lens array 241. Desirably, the beam shaping limiter 242 is located in an area of ​​low electrostatic field strength. Each beam limiting aperture is aligned with a corresponding objective lens in the objective lens array 241. This alignment enables a portion of a sub-beam from the corresponding objective lens to pass through the beam limiting aperture and impinge on the sample 208. The aperture of the beam shaping limiter 242 may have a smaller diameter than the aperture of at least one of the objective lens array 242, the control lens array 250, the detector array 240, and the upper beam limiter array 252. Each beam limiting aperture has a beam limiting effect, allowing only a selected portion of the sub-beam incident on the beam shaping limiter 242 to pass through the beam limiting aperture. The selected portion may enable only a portion of the corresponding sub-beam that passes through the central portion of the corresponding aperture in the objective lens array to reach the sample. The central portion may have a circular cross-section and / or be centered on the beam axis of the sub-beam.

[0069] In one embodiment, the electronic optical device 40 is configured to control the objective lens array assembly (e.g., by controlling the potential applied to the electrodes of the control lens array 250) so that the focal length of the control lens is greater than the spacing between the control lens array 250 and the objective lens array 241. Therefore, the control lens array 250 and the objective lens array 241 can be positioned relatively close, and the focusing effect of the control lens array 250 is too weak to form an intermediate focus between the control lens array 250 and the objective lens array 241. The control lens array and the objective lens array operate together to form a combined focal length to the same surface. Combined operation without an intermediate focus can reduce the risk of aberrations. In other embodiments, the objective lens array assembly can be configured to form an intermediate focus between the control lens array 250 and the objective lens array 241.

[0070] A power source may be provided to apply corresponding potentials to electrodes of control lenses of the control lens array 250 and electrodes of objective lenses of the objective lens array 241 .

[0071] In addition to the objective lens array 241, a control lens array 250 is provided, which provides additional degrees of freedom for controlling the characteristics of the sub-beams. Even if the control lens array 250 and the objective lens array 241 are relatively close, for example, no intermediate focus is formed between the control lens array 250 and the objective lens array 241, additional degrees of freedom can be provided. The control lens array 250 can be used to optimize the opening angle relative to the reduction rate of the beam and / or control the beam energy transmitted to the objective lens array 241. The control lens may include two or three or more electrodes. If there are two electrodes, the reduction rate and the landing energy are controlled together. If there are three or more electrodes, the reduction rate and the landing energy can be controlled independently. Note that the most downstream electrode of the control lens array 250 can be the most upstream electrode of the objective lens array 241. That is, the control lens array 250 and the objective lens array 241 can share electrodes. The shared electrode provides a different lens effect for each lens, and each lens effect is related to one of its two opposing surfaces (i.e., the upstream surface and the downstream surface). Therefore, the control lens can be configured to adjust the reduction ratio and / or beam opening angle of the corresponding sub-beam and / or the energy landing on the substrate (for example, using a power supply to apply appropriate respective potentials to the electrodes of the control lens and the objective lens). This optimization can be achieved without having too much negative impact on the number of objective lenses, and without excessively deteriorating the aberrations of the objective lens (for example, without reducing the strength of the objective lens). The use of a control lens array enables the objective lens array to operate with its optimal electric field strength. Note that references to reduction ratio and opening angle are intended to refer to changes in the same parameter. In an ideal arrangement, the product of the reduction ratio range and the corresponding opening angle is constant. However, the opening angle may be affected by the use of the aperture.

[0072] In one embodiment, the landing energy can be controlled to a desired value within a predetermined range, for example from 1000 eV to 5000 eV. Desirably, the landing energy is changed primarily by controlling the energy of the electrons leaving the control lens. The potential difference within the objective lens is preferably kept constant during this change so that the electric field within the objective lens remains as high as possible. In addition, the potential applied to the control lens can be used to optimize the beam opening angle and the reduction rate. The control lens can change the reduction according to the change in the landing energy. Desirably, each control lens includes three electrodes to provide two independent control variables. For example, one of the electrodes can be used to control the magnification, while the other electrode can be used to independently control the landing energy. Alternatively, each control lens can have only two electrodes. When there are only two electrodes, one of the electrodes may need to control the magnification and the landing energy.

[0073] A detector array (not shown) is used to detect charged particles emitted from the sample 208. The detected charged particles may include any charged particles (e.g., signal particles) detected by a scanning electron microscope, including secondary electrons and / or backscattered electrons from the sample 208. The detector may be an array that provides a surface of the electron-optical device facing the sample 208 (e.g., the bottom surface of the electron-optical device). An alternative detector array may be upstream of the bottom surface, or, for example, located in or upstream of the objective lens array or the control lens array. The elements of the detector array may correspond to sub-beams of a multi-beam arrangement. Signals generated by the detection of electrons by the elements of the array are transmitted to a processor to generate an image. The signals may correspond to pixels of an image.

[0074] In other embodiments, both a macro-scanning deflector and a scanning deflector array 260 are provided. In such an arrangement, scanning of the beamlets on the sample surface can be achieved by controlling the macro-scanning deflector and the scanning deflector array 260 simultaneously (preferably synchronously).

[0075] like Figure 4 As shown, an array of electron-optical devices 500 is provided. The array 500 may include any number of electron-optical devices described herein. Each electron-optical device focuses corresponding multi-beams simultaneously onto different regions of the same sample. Each electron-optical device may form sub-beams from charged particle beams from different corresponding sources 201. Each corresponding source 201 may be one of the multiple sources 201. At least one subset of the multiple sources 201 may be provided as a source array. The source array may include multiple sources 201 disposed on a common substrate. Focusing multiple multi-beams simultaneously onto different regions of the same sample allows a larger area of ​​the sample 208 to be processed (e.g., evaluated) simultaneously. The electro-optical devices in the array 500 may be arranged adjacent to each other so as to project corresponding multi-beams onto adjacent regions of the sample 208.

[0076] Any number of electron-optical devices may be used in array 500. Preferably, the number of electron-optical devices is in the range of two (2), and more preferably nine (9) to one hundred (100) or even two hundred (200). In one embodiment, the electron-optical devices are arranged in a rectangular array or a hexagonal array. In other embodiments, the electron-optical devices are arranged in an irregular array or a regular array having a geometric shape other than a rectangle or a hexagon. Each electron-optical device in array 500 may be configured in any manner described herein with reference to a single electron-optical device, such as described above, particularly with respect to reference Figure 6 Embodiment shown and described. Details of this arrangement are described in EPA20184161.6 filed on July 6, 2020, which is incorporated herein by reference regarding how the objective lens can be incorporated and adapted for use in a multi-device arrangement.

[0077] Figure 4 In the example of FIG. 5 , the array 500 includes a plurality of Figure 3 Electro-optical devices of the type described. Thus, each electron-optical device in this example includes a scanning deflector array 260 and a collimator element array 271. As described above, the scanning deflector array 260 and the collimator element array 271 are particularly suitable for incorporation into the electron-optical device array 500 because of their spatial compactness, which facilitates positioning the electron-optical devices close to each other. This arrangement of electron-optical devices may be advantageous over other arrangements that use magnetic lenses as collimators. For example, incorporating magnetic lenses into electron-optical devices for multi-device arrangements (e.g., multi-device column arrangements) may be challenging due to magnetic interference between columns.

[0078] Alternative designs for multi-beam electron optics may have Figure 3 The same features as described in Figure 5 As shown. An alternative design of the multi-beam electron optical device may include a converging lens array 231 upstream of the objective lens array arrangement 241, as disclosed in EP application 20158804.3 filed on February 21, 2020, which is hereby incorporated by reference for the description of a multi-beam device with a collimator and its components. This design does not require a beam shaping limiter array 242 or an upper beam limiter array 252, because the beam limiting aperture array associated with the converging lens array 231 can shape the sub-beams 211, 212, 213 of the multi-beam of the beam from the source 201. The beam limiting aperture array of the converging lens can also be used as an electrode in the lens array.

[0079] The paths of the beamlets 211, 212, 213 diverge from the converging lens array 231. The converging lens array 231 focuses the generated beamlets to an intermediate focus (i.e., toward the control lens array and the objective lens array) between the converging lens array 231 and the objective lens array assembly 241. The collimator array 271 can be located at the intermediate focus instead of being associated with the objective lens array assembly 241.

[0080] The collimator can reduce the divergence of the divergent beamlet paths. The collimator can collimate the divergent beamlet paths so that they are substantially parallel toward the objective lens array assembly. The corrector array can be present in the multi-beam path, for example, associated with the converging lens array, the intermediate focus, and the objective lens array assembly. The detector 240 can be integrated into the objective lens 241. The detector 240 can be located on the bottom surface of the objective lens 241 so as to face the sample in use.

[0081] exist Figure 5 In the embodiment of the arrangement shown and described, the detector may be located in a similar position in the electron optical device 241 as described in reference Figure 3 The detector 250 may be integrated into the objective lens array 241 and the control lens array 240 (when present, because Figure 5 ). The detector may have a plurality of detectors at different positions along the beamlet paths of the multi-beams, for example, each array being associated with a different electron-optical element, for example, an electrode of an objective lens array and / or a control lens array. The objective lens array 241 and the associated electron-optical elements (e.g., the control lens array 240) may be included in an assembly, which may be a monolithic assembly, which may be referred to as an electron-optical assembly 700. In one embodiment, the detector 240 is associated with the plates 710, 720 of the electron-optical assembly 700, or even integrated therein. For example, the detector 240 may be located on the bottom surface of the electron-optical assembly 700 including the objective lens 241. The detector 240 may be provided with an electrical connection 60, as described elsewhere herein. In one variant, the detector has a detector array located upstream of the objective lens array (optionally and the control lens array 240), for example, located upstream of the electron-optical assembly 700. Between the electron-optical assembly 700 and the detector array may be a Wien filter array, which directs the charged particle beam to the sample in the direction of the lower beam and directs the signal particles from the sample to the detector array.

[0082] The electron optical device array may have a plurality of multi-beam devices of this design, as shown in reference Figure 3 The multi-beam device described in Figure 4As shown. Multiple multi-beam devices can be arranged in a multi-beam device array. Such an arrangement is shown and described in EP application 20158732.6 filed on February 21, 2020, which is hereby incorporated by reference with respect to the multi-device arrangement of a multi-beam device, which is characterized by the design of a multi-beam device disclosing a collimator at an intermediate focus.

[0083] Another alternative design of a multi-beam device includes multiple single-beam devices. A single beam produced for the purpose of the invention described herein may be similar to or equivalent to a multi-beam produced by a single device. Each device may have an associated detector. This multi-device device can be arranged in an array of three, four, nine, nineteen, fifty, one hundred or even two hundred devices, each of which produces a single beam or beamlet (if a single-beam device) or multiple beams (if a multi-beam device). In this alternative design, the array of devices may have a common vacuum system, each device may have a separate vacuum system or groups of devices may be assigned different vacuum systems. Each device may have an associated detector.

[0084] Electron optical device 40 may be part of an evaluation (eg inspection or metrology inspection) apparatus or part of an electron beam lithography apparatus.Multi-beam charged particle devices can be used for a variety of different applications, including electron microscopy in general (not just scanning electron microscopy) and lithography.

[0085] The electron optical axis 304 describes the path of the charged particles through the source 201 and out of the source 201. Unless explicitly mentioned, the beamlets and beamlets of the multi-beam may all pass through at least a manipulator or an electron optical array (e.g., see Figure 2 The arrangement shown and described) is substantially parallel to the electron optical axis 304. The electron optical axis 304 can be the same as or different from the mechanical axis of the electron optical device 40. Figures 2 to 5 In the arrangement shown and described, the electron optical axis can correspond to the path of the central beam of the multi-beam (e.g., beam 212). The beams of the multi-beam are collimated (e.g., at the position of the collimator array 271, which corresponds to the intermediate focal plane (e.g., as shown in FIG. Figure 5 The beam limiter 252 (shown) or upper beam limiter 252) and the surface of the sample 208 are substantially parallel to each other (e.g., the electron optical axis 304).

[0086] The electronic optical device 40 may include Figure 6The electron optical assembly 700 shown is used to manipulate the electron beam. For example, the electron optical assembly 700 may include one or more of the following (in a non-limiting list): the objective lens array 241, and / or the converging lens array 231 may include the electron optical assembly 700 and / or the collimator element array 271 and / or a separate beam corrector and / or deflector and / or Wien filter array. Specifically, the objective lens 331 and / or the converging lens 310 and / or the control lens 250 may include the electron optical assembly 700.

[0087] Electro-optical components are configured to provide a potential difference between two or more plates (or substrates). An electrostatic field is generated between the plates, which act as electrodes. The electrostatic field causes an attractive force between the two plates. The attractive force can increase as the potential difference increases.

[0088] In an electron optical assembly, at least one plate has a stepped thickness, so that the array plate is thinner in a region corresponding to the aperture array than in another region of the array plate. It is advantageous to have a stepped thickness, for example, two parts of the plate have different thicknesses, because at high potential differences, the plate is subjected to higher electrostatic forces, which can lead to bending if the plate is of uniform thickness and, for example, too thin. Bending of the plate can have an adverse effect on the uniformity between beams. Therefore, thick plates are advantageous in reducing bending. However, if the plate is too thick in the region of the aperture array, it can lead to undesirable deformation of the electron beam. Therefore, a thin plate around the aperture array is advantageous in reducing deformation of the electron beamlets. That is, the aperture array can be defined in a region of the plate that is thinner than the rest of the plate. Therefore, the stepped thickness of the plate reduces the possibility of bending without increasing the possibility of deformation of the beamlets. In one embodiment, the plate has a uniform thickness, including in the region corresponding to the aperture array.

[0089] Figure 6 The exemplary electron optical assembly shown includes an array plate 710, an adjacent plate 720, and an isolator (or spacer) 730. (Note that the term "array plate" is a term used to distinguish this plate from other plates mentioned in the specification). In the array plate, an aperture array 711 is defined for the path of the electron beam. The number of apertures in the aperture array can correspond to the number of sub-beams in the multi-beam arrangement. In one arrangement, the apertures are fewer than the sub-beams in the multi-beam so that the sub-beam path groups pass through the apertures. For example, the apertures can extend through the multi-beam paths; the apertures can be strips or slits. In one arrangement, the apertures can be arranged as a grid (or a two-dimensional array) so that the beam groups are arranged as a two-dimensional array of beam groups. The isolator 730 is disposed between the plates to separate the plates. The electron optical assembly is configured to provide a potential difference between the array plate 710 and the adjacent plate 720.

[0090] In the adjacent plate 720, another aperture array 721 is defined for the path of the electron beam. In one embodiment, the thickness of the adjacent plate 720 can also be stepped so that the adjacent plate is thinner in the area corresponding to the aperture array than in another area of ​​the adjacent plate. (Alternatively, the adjacent plate 720 is substantially planar and / or has a uniform thickness). Desirably, the aperture array 721 defined in the adjacent plate 720 has the same pattern as the aperture array 711 defined in the array plate 710. In the arrangement, the patterns of the aperture arrays in the two plates can be different. For example, the number of apertures in the adjacent plate 720 can be less than or more than the number of apertures in the array plate 710. In the arrangement, there is a single aperture in the adjacent plate for all sub-beam paths of the multi-beam. Preferably, the apertures in the array plate 710 and the adjacent plate 720 are substantially well aligned with each other. This alignment between the apertures is to limit lens aberrations.

[0091] The array plate and the adjacent plate may each have a thickness of up to 1.5 mm, preferably 1 mm, more preferably 500 μm at the thickest point of the plate. In one arrangement, the downstream plate (i.e., the plate close to the sample) may have a thickness of between 200 μm and 300 μm at its thickest point. The downstream plate preferably has a thickness of between 200 μm and 150 μm at its thickest point. The upstream plate (i.e., the plate away from the sample) may have a thickness of up to 500 μm at its thickest point.

[0092] The coating may be provided on the surface of the array plate and / or the adjacent plate. Preferably, the coating is provided on both the array plate and the adjacent plate. The coating may reduce surface charging which would otherwise cause unwanted beam distortion.

[0093] The coating is configured to withstand electrical breakdown events that may occur between the array plate and an adjacent plate. Preferably, a low ohmic coating is provided, more preferably a coating of 0.5 ohm / square or less is provided. The coating is preferably disposed on the surface of the downstream plate. The coating is more preferably disposed between at least one plate and the separator. The low ohmic coating reduces undesirable surface charging of the plate.

[0094] The array plate and / or the adjacent plate may comprise a low bulk resistance material, preferably a material of 1 Ohm.m or less, optionally 0.1 Ohm.m or less, optionally 0.01 Ohm.m or less, optionally 0.001 Ohm.m or less, optionally 0.0001 Ohm.m or less. More preferably, the array plate and / or the adjacent plate comprise doped silicon. Plates with low bulk resistance have the advantage that they are less likely to fail because the discharge current is supplied / drained through the bulk resistance rather than, for example, through a thin coating.

[0095] The array plate includes a first wafer. The first wafer can be etched to generate regions with different thicknesses. The first wafer can be etched in the region corresponding to the aperture array so that the array plate is thinner in the region corresponding to the aperture array. For example, the first side of the wafer can be etched or both sides of the wafer can be etched to generate a stepped thickness of the plate. The etching can be performed by deep reactive ion etching. Alternatively or additionally, the stepped thickness of the plate can be generated by laser drilling or machining.

[0096] Alternatively, the array plate may include a first wafer and a second wafer. The aperture array may be defined in the first wafer. The first wafer may be arranged to contact the isolator. The second wafer is arranged on the surface of the first wafer in an area not corresponding to the aperture array. The first wafer and the second wafer may be connected by wafer bonding. The thickness of the array plate in the area corresponding to the aperture array may be the thickness of the first wafer. In addition to the area of ​​the aperture array, the thickness of the array plate in another area, such as the radial outer side of the aperture array, may be the combined thickness of the first wafer and the second wafer. Therefore, the array plate has a stepped thickness between the first wafer and the second wafer.

[0097] One of the array plate and the adjacent plate is located upstream of the other. One of the array plate and the adjacent plate is negatively charged relative to the other plate. Preferably, the upstream plate has a higher potential than the downstream plate relative to, for example, ground potential, a source or a sample. The electron optical assembly can be configured to provide a potential difference of 5 kV or greater between the array plate and the adjacent plate. Preferably, the potential difference is 10 kV or greater. More preferably, the potential difference is 20 kV or greater, or less than 30 kV or even greater than 30 kV.

[0098] The isolator 760 is preferably disposed between the array plate and the adjacent plate so that the opposing surfaces of the plates are coplanar with each other. The isolator 760 has an inner surface 731 facing the beamlet path. The isolator may be planar with its major surface coplanar with the plates 710, 720. The isolator 760 defines an opening 732 for the path of the electron beamlets.

[0099] A conductive coating may be applied to the separator, such as coating 740. Preferably, a low ohmic coating is provided, and more preferably, a coating of 0.5 ohms / square or less is provided.

[0100] The coating is preferably located on the surface of the space facing the negatively charged plate, which surface is negatively charged relative to the other plate. The downstream plate is preferably negatively charged relative to the upstream plate. The coating should be at the same potential as the negatively charged plate. The coating is preferably located on the surface of the separator facing the negatively charged plate. The coating is more preferably electrically connected to the negatively charged plate. The coating ensures that there is an electrostatic field over any possible gap between the separator and the negatively charged plate.

[0101] Without this coating on the isolator, an electric field enhancement may occur in these voids. This electric field enhancement may cause electrical breakdown in these voids, resulting in an instability in the potential of the lower electrode. This potential instability causes the lens strength to vary over time, defocusing the electron beam.

[0102] The shape of the inner surface 731 of the spacer 760 (or edge) is such that the creepage path between the boards on the inner surface is longer than the minimum distance between the boards. The inner surface may have a step 761. The step may be a step of the thickness of the isolator. The step may have a surface coplanar with the main surface of the isolator. Thus, the creepage length is on the inner surface 731 of the spacer between two different boards, for example on the step 761. Desirably, the shape of the inner surface of the isolator provides a creepage length of 10 kV / mm or less, preferably 3 kV / mm or less.

[0103] Electron optical assembly 700 may include or be a lens assembly for manipulating the electron beam. The lens assembly may be, for example, an objective lens assembly or a converging lens assembly, or may be a part of an objective lens assembly or a converging lens assembly. The lens assembly (e.g., an objective lens assembly) may also include an additional lens array including at least two plates, such as control lens array 250.

[0104] Figure 7 FIG. 7 is a schematic diagram of an electrical connector 60 of an exemplary electron optical assembly 700. The electron optical assembly 700 is configured to manipulate an electron beam. Figure 7 As shown, in one embodiment, the electron-optical assembly 700 includes a first electron-optical element, which includes a board 710. (Note that if the electron-optical assembly 700 includes only one first electron element, the first electron-optical element may be referred to as an electron-optical element).

[0105] In one embodiment, the electron-optical assembly 700 includes a plurality of electron-optical elements, each of which includes a plate. For example, Figure 6 The illustrated electron-optical assembly 700 includes a first electron-optical element including a board 710 and a second electron-optical element including a board 720. In one embodiment, the electron-optical assembly 700 includes more than two electron-optical elements, each of which includes a board. The electrical connector 60 described herein may be used to connect any one or each of the boards 710, 720 of the electron-optical assembly 700 to a power source (or power supply).

[0106] In one embodiment, the plate 710 has one or more apertures 711 surrounding the beam path of the electron beam. Figure 6As shown, in one embodiment, the plate 710 includes an array of apertures 711. In an alternative embodiment, the plate 710 includes only one aperture. Each aperture 711 can be used for the beam path of a single electron beam. Alternatively, one or more apertures 711 can surround the beam paths of multiple electron beams.

[0107] Figure 7 An electrical connector 60 is schematically shown. The electrical connector 60 is configured to electrically connect the board 710 of the first electron-optical element to a power source. In one embodiment, the electron-optical device 40 comprises the electrical connector 60. In one embodiment, the electron-optical assembly 700 comprises the electrical connector 60.

[0108] In one embodiment, the power supply is a high voltage power supply. In one embodiment, the power supply is configured to apply at least 100V, optionally at least 200V, optionally at least 500V, optionally at least 1kV, optionally at least 2kV, optionally at least 5kV, optionally at least 10kV, optionally at least 20kV, optionally at least 30kV, and optionally up to or even exceeding 35kV voltage to a part of the electronic optical assembly 700 relative to the reference potential of the electronic optical device 40. In one embodiment, the power supply is configured to apply a positive voltage relative to the reference potential. In an alternative embodiment, the power supply is configured to apply a negative voltage relative to the reference potential. The reference potential can be grounded. In one embodiment, one or more plates 710, 720 of the electronic optical assembly 700 are configured to be connected to a high voltage during use of the electronic optical device 40.

[0109] Figure 7 An electrical connector 60 is shown for electrically connecting a plate 710 (i.e., a planar electron optical element) to a power source (e.g., a voltage source). The planar electron optical element is configured to operate on an electron beam along a beam path toward a sample location. The electron optical element can be configured to operate on a single electron beam or multiple electron beams (e.g., a multi-beam), which can be formed in a beam grid. In one embodiment, the electron optical element includes an aperture 711 (or an aperture array) for the beam path.

[0110] In one embodiment, electrical connector 60 is used to electrically connect board 710 to a power source. Board 710 may be part of an electronic optical assembly 700, which may include, for example, an objective lens assembly or a converger assembly. More generally, electrical connector 60 may be configured to electrically connect any electronic optical element of electronic optical device 40 to a power source.

[0111] like Figure 7As shown, in one embodiment, the electronic optical assembly includes an electrical conductor 61. The electrical conductor 61 is electrically connected to the electronic optical element (i.e., board 710). In one embodiment, the electrical conductor 61 is included in the electrical connector 60. The electrical conductor 61 is used to electrically connect the board 710 to a power source. The electrical conductor 61 includes a conductive material. The electrical conductor 61 may include a metal.

[0112] like Figure 7 As shown, in one embodiment, a groove 611 (e.g., having a concave surface) is defined in the conductor 61. In one embodiment, the groove 611 is configured to provide a field-free volume 62. The opening defined in the end face 613 of the conductor 61 is the opening of the groove 611, and therefore is the opening of the field-free volume 62. In one embodiment, the field-free volume 62 is used to insert a high-voltage cable 64. In one embodiment, the high-voltage cable 64 is used to electrically connect the electron-optical element to a power source. In one embodiment, the high-voltage cable 64 is configured to electrically connect the electron-optical element to a power source through an electrical coupler 63. The field-free volume 62 is substantially free of an electric field. In one embodiment, the conductor 61 is configured to shield the electrical components within the field-free volume 62 from external electric fields. In one embodiment, the conductor 61 is configured to reduce the possibility of electrical breakdown between the electrical components within the field-free volume 62 and another component of the electron-optical device 40.

[0113] The high voltage cable 64 may include an insulator 65 and a conductor 66. The conductor 66 is a transmission line. The insulator 65 is used to isolate the conductor 66 from the environment.

[0114] In one embodiment, the electrical coupler 63 is flexible. The flexible coupler can be located in the electrical path between the board 710 and the power source. In one embodiment, the flexible coupler is configured to electrically connect the board 710 to the power source, for example, so that the electrical connector 60 can connect the board 710 to the power source. The board 710 can be electrically connected to the power source through the flexible coupler 63. Therefore, the board 710 can be electrically connected to the power source through the cable. The electrical path can include: a high voltage cable 64, an electrical connector 60 (e.g., including a flexible connector 63) and a board 710.

[0115] like Figure 7 As shown, in one embodiment, the flexible coupler 63 is located within a field-free volume 62 (or field-free region) defined, for example, in the electrical conductor 61. The flexible coupler 63 is intended to provide an electrical connection to the board 710, for example via an electrical connection to the electrical conductor 61. The electrical conductor 61 is configured to shield the flexible coupler 63 from electric fields external to the electrical conductor 61. One embodiment of the present invention is expected to reduce the likelihood of electrical breakdown associated with the (electrical) connection of the electronic-optical device to a power source, for example between the electrical connector 60 and another component of the electronic-optical device 40 (for example, another component of the electronic-optical assembly 700).

[0116] The flexibility of the flexible coupler 63 reduces the possibility that the electrical connector 60 adversely affects the position and / or formation (e.g., shape) of the plate 710. Such a flexible coupler connected to an electron-optical device can reduce the risk of applying forces and / or torques to the electron-optical device. Applying such forces or torques may adversely affect the electron-optical performance of the electron-optical device during device operation. Such effects on the performance of the electron-optical device can be observed, for example, from the position of the device, thereby being observed from the alignment of the device with the sample, relative to one or more charged particle beams and the alignment between the charged particle beams, and other aberrations. Such aberrations may be caused, for example, by changes in stress within the device and / or the formation of the device, such as by deformation of the shape of the components of the device, causing the field generated in the device to be distorted.

[0117] like Figure 7 As shown, in one embodiment, the electrical conductor 61 includes an electrical insulator 70. In one embodiment, the electrical insulator 70 is spaced apart from the planar electron-optical element. There may be a gap between a component of the planar electron-optical element (e.g., plate 710) and the electrical insulator 70. In one embodiment, the electrical insulator 70 provides at least a portion of the surface of the electrical conductor 61. Alternatively, the electrical insulator 70 may be considered a component different from the electrical conductor 61 (so that the electrical conductor 61 does not include the electrical insulator 70). In this case, the electrical insulator 70 is configured to cover at least a portion of a surface 612 of the electrical conductor 61. In one embodiment, the surface (or a portion of the surface) 612 of the electrical conductor 61 covered by the electrical insulator 70 faces away from the electron-optical element.

[0118] Embodiments of the present invention are expected to reduce the likelihood of electronic creepage. Electronic creepage may occur between different parts of the electronic optical device 40. For example, as will be explained in more detail below, in one embodiment, the electronic optical assembly includes a plurality of electrical conductors 61 (a plurality of corresponding electrical connectors 60). Electronic creepage may occur between the electrical conductors 61. Additionally or alternatively, electronic creepage may occur between the electrical conductors 61 and the electronic optical components of the electronic optical assembly, except for the board 710 to which the electrical conductors 61 are electrically connected. Such electronic creepage is undesirable.

[0119] By providing an electrical insulator, the likelihood of electron creepage occurring due to electrons being released from the electrical conductor 61 is reduced. The likelihood of undesirable electron creepage occurring is particularly high in the case of high electric fields. By providing an electrical insulator 70, the electrical connector 60 can withstand higher electric fields without unduly increasing the risk of electron creepage.

[0120] Generally speaking, when the outer surface of the conductor 61 has relatively sharp edges and / or a small radius of curvature, the electric field around the conductor 61 may be higher. By providing the electrical insulator 70, the size of the conductor 61 can be reduced (which will increase the electric field around the conductor 61) without excessively increasing the risk of electronic creepage. Embodiments of the present invention are expected to increase the design freedom of the conductor 61.

[0121] like Figure 7 As shown, in one embodiment, the electron optical assembly includes a plurality of isolators 750, 760. In one embodiment, the plate 710 is located between the isolators 750, 760, for example, sandwiched by the isolators 750, 760. For ease of reference to distinguish the two isolators used in this specification, the two isolators may be referred to as upstream isolators 750 and downstream isolators 760. However, the description of the upstream isolator may be applicable to the downstream isolator, and vice versa. In addition, these terms are related to the two isolators, so the electron optical module 700 may include another isolator, such as located at a relatively upstream or downstream position of the two isolators 750, 760. In one embodiment, the isolators 750, 760 are substantially planar. The isolators 750, 760 and the plate 710 may be stacked on each other. The electron optical assembly may include a plurality of plates and a plurality of isolators. The combination of plates and isolators stacked relative to each other may be referred to as a stack.

[0122] In one embodiment, the downstream isolator 760 is configured to support the electron optical element. In this embodiment, the downstream isolator 760 is configured to electrically isolate the electron optical element. In one embodiment, the downstream isolator 760 is positioned away from the beam path, for example, around the beam path. The downstream isolator 760 can be a plate in which an aperture for the beam path is defined, and the surface of the plate in the aperture can be referred to as an edge or inner surface 731. The edge can be spaced apart from the beam path (or positioned away from the beam path). The edge can be spaced apart from the beam path and the location of one or more apertures 711, 721 in the plates 710, 720 that contact the isolator 760.

[0123] like Figure 7 As shown, in one embodiment, the electronic optical assembly includes a conductor 67. The conductor 67 is configured to electrically connect the board 710 to the electrical conductor 61. In one embodiment, the conductor 67 includes a conductive layer groove, such as a coating. The conductive layer can be formed, for example, as a coating on the downstream isolator 760. The conductor 67 is electrically connected to the electrical conductor 61. For example, in one embodiment, a conductive adhesive (e.g., glue) such as a ridge is provided to electrically connect the conductor 67 to the electrical conductor 61. Additionally or alternatively, the conductor 67 can be electrically connected to the electrical conductor 61 by, for example, welding and / or clamping.

[0124] like Figure 7As shown, in one embodiment, the conductor 61 is located on the downstream isolator 760. In one embodiment, the downstream isolator 760 is configured to mechanically support the conductor 61. Figure 7 As shown, in one embodiment, the plate 710 and the electrical conductor 61 electrically connected to the plate 710 are both supported by the same downstream isolator 760. However, this is not necessarily the case. In one embodiment, the electrical conductor 61 and the plate electrically connected thereto may be directly supported by different isolators of the electronic optical assembly. For example, in Figure 7 In a modified version of the arrangement shown, the conductor 61 is electrically connected to another plate mechanically supported by the upstream isolator 750. The conductor 61 may still be supported by the downstream isolator 760. However, the conductor 67 will be located on the upstream isolator 750 (rather than the downstream isolator 760) to extend toward the conductor 61 and electrically connected to the conductor 61. In one embodiment, the conductor 67 is electrically connected to a position in the middle of the conductor 61 along the beam path direction (rather than Figure 7 The bottom of the conductor 61 is shown).

[0125] For example, Figure 7 As shown, in one embodiment, the electrical insulator 70 is thicker than the electrical conductor 61, wherein the electrical insulator 70 covers the surface 612 of the electrical conductor 61. By providing the electrical insulator 70, the size of the electrical conductor 61 can be reduced because the electrical insulator 70 allows a larger electric field to exist around the electrical conductor 61 without excessively increasing the risk of electrical breakdown. By reducing the size of the electrical conductor 61, more available volume can be provided for the electrical insulator 70. For example, in Figure 7 or Figure 8 In the view shown, the thickness of the insulating cover 71 is greater than the thickness of the electrical conductor 61 or the conductive element of the electrical conductor. In one embodiment, the thickness is measured in a direction away from the axial direction of the field-free volume 62. The conductive element may be located within the electrical insulator 70. The conductive element may include, for example, a conductive layer on the electrical insulator 70. The electrical conductor may have an end face.

[0126] Figure 8 It is a schematic diagram of the components of an electron optical assembly. Figure 8 The electron optical components shown can be Figure 7 An improved version of the electron-optical assembly is shown. Figure 8 The features of the electron optical assembly shown are similar to those of the Figure 7 The following description focuses on Figure 8 The electronic optical components are not Figure 7 Features shown in .

[0127] like Figure 8As shown, in one embodiment, the end face 613 of the conductor 61 includes a portion of the surface of the conductor 61 provided by the electrical insulator 70. In one embodiment, the electrical insulator 70 covers the end face 613 of the conductor 61. An opening to the field-free volume 62 is defined in the end face 613. The conductor can have a sharp edge 68 or an end of, for example, a conductive layer 78. The sharp edge 68 can be provided by the opening in the end face 613 of the conductor 61 and / or the interface between the insulator 71 or separator 760 and the conductive material of the conductor 61 (e.g., conductive layer 78). For conductors formed by a thin conductive layer (e.g., a coating), the sharp edges defined by the opening and the interface can actually be substantially the same. References to one sharp edge below may also apply to situations where the two sharp edges are different.

[0128] like Figure 7 As shown, at the end face 613 of the conductor 61, for example at the sharp edge 68, there may be a triple point. The triple point is the junction between the conductive surface, the insulating surface, and the surrounding environment or atmosphere (which may be at a low pressure, such as a vacuum). The triple point at the sharp edge 68 is the junction between the conductive elements of the conductor 61, the electrical insulator 70, and the atmosphere. Typically, undesirable electronic creepage may start at or near such a triple point. Figure 8 and Figure 7 As can be seen from the comparison, in one embodiment, the sharp edge is covered by the electrical insulator 70. Covering the sharp edge 68 can prevent the sharp edge from acting as a triple point. Figure 7 The sharp edge 68 shown in FIG. 6 can be considered to have been captured or encapsulated by the electrical insulator 70. As a result of the encapsulation, there is a triple point within the field-free volume 62. Figure 8 As shown, there is an interface 69 with the insulating surface and the atmosphere on the concave surface of the conductor 61. In fact, the position of the triple point is moved from the sharp edge 68 at the end face 613 of the conductor 61 to the field-free volume 62. By arranging the conductor 61 so that the triple point is located within the field-free volume 62, for example at the interface 69, the possibility of electron creepage is reduced. Specifically, by moving the triple point from the surface of the sharp edge 68 at the end face 613 of the conductor to the interface 69 within the field-free volume 62, the surface required for electron creepage to occur can be increased. Moving the position of the triple point to the field-free area increases the size of the surface where electron creepage occurs when a discharge occurs. Therefore, by moving the triple point (i.e., as the starting point of such electron creepage) to the field-free volume, discharge caused by electron creepage can be prevented, or at least the risk can be reduced.

[0129] In one embodiment, the sharp edges (or sharp ends) 68 of the conductor 61 are encapsulated to reduce or even prevent electron release and move the triple point into the field-free volume 62. Figure 8As shown, in one embodiment, the electrical insulator includes an insulating member 72 as the end face 613 of the electrical conductor 61. The insulating member covers the sharp edge 68. In one embodiment, the electrical insulator 70 at the end face includes an insulating member 72, which covers the end face 613 (or face) of the electrical conductor 61. In one embodiment, the insulating member 72 is formed integrally. In one embodiment, the insulating member 72 is initially formed as a separate component from the rest of the electrical insulator 70. For example, in one embodiment, the electrical insulator 70 includes an insulating member 72 and an insulating cover 71. The insulating cover 71 is configured to cover at least a portion of the outer surface 612 of the electrical conductor 61. In one embodiment, the electrical insulator 70 has at least two pieces.

[0130] In one embodiment, the insulating member 72 includes an insulating plug that includes (or at least covers) an end face of the conductor 61. In one embodiment, the insulating plug extends through an opening to the field-free volume 62 to provide at least a portion of the surface (or concave surface) of the groove 611. In one embodiment, the insulating plug extends into the field-free volume 62. The portion of the plug extending into the groove 611 may be referred to as an inward portion. In one embodiment, the insulating member 72 is an insulating plug that engages with the end face 613 of the conductor 61. The portion of the plug covering the end face of the conductor 61 may be referred to as a covering portion. In one embodiment, the insulating member 72 is configured to engage with an inner surface of the conductor 61, such as within the groove 611.

[0131] The electrical insulator 70 includes an electrically insulating material. For example, in one embodiment, the electrical insulator includes a dielectric such as ceramic, glass (e.g., borosilicate glass) and epoxy resin or an insulating adhesive. In one embodiment, the insulating cover 71 and the insulating member 72 are formed of the same dielectric material. Alternatively, the insulating cover 71 may include a material different from that of the insulating member 72.

[0132] In one embodiment, the conductor 61 is formed into a block of conductive material by milling, machining, cutting or laser ablation or other such forming methods. In one embodiment, the conductor 61 includes rounded edges. In one embodiment, the conductor 67 has one or more rounded edges. The rounded edges can help reduce the electric field around the conductor 61 and / or the conductor. This is because the surface rounding of the conductor 61 can help limit the local field enhancement in the insulator covering the conductor 61. Limiting the local field enhancement ensures that the field does not exceed the dielectric strength of the insulator. If the field does exceed locally, such as at the edge of the conductor 61, electrical breakdown of the insulator may occur. In one embodiment, the conductor 61 is formed as a layer such as a coating. For example, the conductive material can be applied (e.g., coated) in the form of a layer to the surface of the downstream isolator 760 and / or the electrical insulator 70 to form the conductor 61 or at least a conductive element of the conductor 61. For example, the conductive layer 78 can be formed by one continuous layer. In another embodiment, the conductive layer 78 may be formed by at least a portion of a layer on the separator 760 and a layer on a surface of an electrical insulator (eg, insulating cover 71), for example, the layer on the separator may be bonded to the layer on the electrical insulator.

[0133] The electrical insulator 70 does not necessarily include the insulating member 72. Likewise, the electrical insulator 70 does not necessarily include the insulating cover 71. In one embodiment, the electrical insulator 70 is composed of the insulating member 72. A portion of the outer surface 612 of the electrical conductor 61 may be covered by the downstream isolator 760 and the insulating member 72, while the other portion of the outer surface 612 of the electrical conductor 61 is exposed to the environment.

[0134] like Figure 8 As shown, in one embodiment, the electrical insulator 70 extends from the end face 613 into the field-free volume 62. In one embodiment, the electrical insulator 70 provides a portion of the inner surface of the electrical conductor 61 (or the concave surface of the groove 611). In one embodiment, the electrical insulator 70 provides a portion of the inner surface of the electrical conductor away from the electron optical element. In one embodiment, the inner surface of the electrical conductor 61 defines the field-free volume 62. In one embodiment, the electrical insulator 70 extends into the field-free volume 62, covering a portion of the inner surface of the electrical conductor 61, which defines the field-free volume 62. In other words, the concave surface can include the surface of the inward portion of the plug and a portion of the electrical conductor 61. This portion of the electrical conductor 61 can be referred to as an exposed portion of the electrical conductor. The exposed portion is the portion of the electrical conductor surface in the groove 611 that remains exposed, such as a portion that is not covered by the plug (or insulating member 72).

[0135] In one embodiment, at least a portion of the electrical insulator 70 surrounds a cross-section of the electrical conductor 61. Figure 7 and Figure 8In the arrangement shown, a cross section of the conductor 61 perpendicular to the axial direction of the field-free volume 62 is surrounded by a combination of an insulating cover 71 and a downstream isolator 760. In an alternative embodiment, the insulating cover 71 surrounds the cross section of the conductor 61. One embodiment of the present invention is expected to reduce the likelihood of electrons creeping on the surface of the conductor 61, such as forming a triple point in any direction, such as from the edge of the exposed (or uncovered) conductive surface of the conductor.

[0136] like Figure 7 As shown, in one embodiment, the longitudinal axis of the field-free volume 62 is offset from the plate 710 of the electron-optical element. In one embodiment, the field-free volume 62 defines an axial direction at a distance from the plane of the planar electron-optical element. The distance between the end of the electrical conductor 61 and the electron-optical element of the stack can be increased to reduce the risk of discharge between the electrical conductor 61 and the stack. There can be a gap between the end of the electrical conductor 61 and the electron-optical element of the stack.

[0137] In one embodiment, the field-free volume 62 defines an axial direction that is at an angle relative to the plane of the planar electron-optical element. For example, in one embodiment, the axial direction of the field-free volume 62 is angled outwardly from the plane of the planar electron-optical element. For example, the field-free volume 62 can be directed upward or downward relative to the plate 710, such as Figure 7 By changing the angle of the conductor 61, the end of the conductor 61 can be moved away from the stack, thereby reducing the risk of discharge. If the available design volume is limited, this configuration can also facilitate the electrical connection of the conductor and thus the electronic optical element. However, it is not necessary that the field-free volume 62 is at a certain angle relative to the plate 710. In an alternative embodiment, the axial direction defined by the field-free volume 62 is parallel to the plane of the plate 710, for example Figure 7 shown.

[0138] Fig. 9 is a schematic plan view of an electro-optical assembly including two electrical connectors 60. In one embodiment, the electrical connectors 60 are used to electrically connect corresponding electro-optical elements of the electro-optical assembly to corresponding power sources. Fig. 9 As shown, in one embodiment, the electronic optical assembly includes a plurality of electrical conductors 61. The electrical conductors 61 are electrically connected to one or more electronic optical elements of the electronic optical assembly. For example, Fig. 9 The electrical connector 60 shown in the upper part is used to electrically connect the board 710 to a power source. The electrical conductors 61 are electrically connected to the board 710 of electron optics. One or more apertures may be defined in the board for the path of one or more charged particle beams. Fig. 9 The electrical connector 60 shown in the lower portion may be used to electrically connect another board in the electro-optical assembly stack to the same or another power source.

[0139] In one embodiment, an electron-optical device including an electron-optical assembly includes a plurality of power supplies. In one embodiment, a controller 50 is provided to control the voltage applied by the power supply to the electron-optical element. In one embodiment, the controller 50 is configured to control different high voltages applied to different electron-optical elements of the electron-optical assembly. Additionally or alternatively, a plurality of power supplies may be connected to different parts of the same electron-optical element. The controller 50 may control the power supplies so that different high voltages are applied to different parts of the electron-optical element. The controller 50 is configured to control the voltage applied to the electron-optical element, thereby controlling the manipulation of one or more electron beams by the electron-optical assembly.

[0140] Fig. 9 Many of the features shown in the drawings have been described above in conjunction with other drawings. These features are marked with the same reference numerals as used previously herein. These features will not be described in detail again to avoid duplication of description. The following description focuses on features not shown in other drawings.

[0141] like Fig. 9 As shown, in one embodiment, the electrical insulator 70 covers at least a portion of the surface of the plurality of electrical conductors 61. For example, Fig. 9 As shown, in one embodiment, the electrical insulator 70 includes a potting material 73. The potting material includes an insulating material. The potting material 73 is configured to cover the outer surface of one or more electrical conductors 61. The potting material 73 is configured to reduce the possibility of electrons being released from the electrical conductor 61. The potting material 73 is provided to reduce or eliminate voids / air pockets or vacuums that may undesirably enhance the electric field. In one embodiment, the potting material 73 is formed by a fluid that is cured to form a dielectric layer. In one embodiment, the potting material 73 includes, for example, an epoxy resin or an insulating adhesive. In one embodiment, the electrical insulator 70 includes at least a portion of a surface shared by a plurality of electrical conductors 61. In one embodiment, the electrical insulator 70 is shared by a plurality of electrical conductors 61.

[0142] like Fig. 9 As shown, in one embodiment, in plan view, multiple conductors 61 are located on the same side of the beam path. The beam path extends through the central area of ​​the plate 710. For ease of description, the stack is shown as having a square cross-sectional shape, but it can have any desired shape disclosed herein. Fig. 9 As shown, in one embodiment, a plurality of electrical conductors 61 define a field-free volume 62 having axial directions parallel to each other. Electrical connectors 60 may extend from the same side of the stack of layers of the electro-optical assembly. This may reduce the space occupied by electrical connections on other sides of the stack, for example to meet volume constraints in an electro-optical device.

[0143] Fig.10 is a schematic plan view of an electron optical assembly. Unless otherwise indicated, it has the same Fig. 9 Same features and description. Fig.10 The electro-optical assembly shown has two electrical conductors 61 on opposite sides of the stack of layers of the electro-optical assembly. Fig.10 As shown, in one embodiment, two electrical conductors 61 are arranged to have a beam path between them; as depicted, the cross-sectional shape of the stack across the beam path can be square. Electrical conductors 61 can be further separated from each other by positioning electrical conductors 61 on different sides of the stack of electron-optical components. By further separating electrical conductors 61 from each other, the length of the creepage path between electrical conductors 61 can be extended. However, it is not necessary that the two electrical conductors 61 be arranged to have a beam path between them. For example, as Fig. 9 As shown, in one embodiment, all electrical connectors 60 are placed on the same side of the electronic optical assembly. Fig. 9 Compared to the arrangement shown and described, the electrical connector is placed on the adjacent side, for example, to address volume constraints and increase the creepage length between two electrical conductors (or between triple points of two electrical conductors).

[0144] like Fig. 9 and Fig.10 As shown, in one embodiment, the electrical insulator 70 includes a housing 74. In one embodiment, the housing 74 includes a dielectric, such as ceramic and / or glass (e.g., borosilicate glass). In one embodiment, a potting material 73 is provided to fill the gap between the housing 74 and the electrical conductor 61. The potting material 73 may be provided after the electrical conductor 61 is positioned relative to the housing 74 of the electrical insulator 70. Fig. 9 or Fig.10 As shown, in one embodiment, when viewed in a plan view, the housing 74 substantially surrounds the stack of electronic optical components. In one embodiment, the potting material is filled between the housing and the stack. The potting material can fill the gaps between the stack and each conductor 61.

[0145] Fig. 9 Two electrical conductors 61 are shown on the same side of the electronic optical component. The electrical conductors 61 are adjacent to each other. Fig. 9 As shown, in one embodiment, the housing 74 defines a middle groove between the electrical conductors 61. In an alternative embodiment, the groove is filled with material forming the housing 74. The housing 74 can be thicker in this area. In another embodiment, the housing 74 bridges the middle groove in the manner of, for example, a straight line between two electrical conductors 61. The middle groove is filled with potting material 73. In this case, the potting material will be thicker, for example, compared to the previous example where the housing 74 is thicker.

[0146] For example, in Fig.10 In the arrangement shown, Fig.10The electrical conductor 61 on the right is electrically connected to the board 710 via the conductor 67 . Fig.10 The electrical conductor 61 on the left is electrically isolated from the board 710 by the potting material 73 of the electrical insulator 70 . Fig.10 The conductor 61 on the left is electrically connected to another electro-optical element of the electro-optical assembly including the board 710. Fig.10 As shown (and Fig. 9 In one embodiment, the electrical insulator 70 extends between the electrical conductor 61 and one or more additional electron optical elements configured to operate the electron beam. The electrical insulator 70 is configured to reduce the possibility of electrical breakdown between the electrical conductor 61 and other electron optical elements of the electron optical assembly. In one embodiment, the electrical insulator 70 extends toward one or more additional electron optical elements configured to operate the electron beam. In one embodiment, the electrical insulator 70 extends to one or more additional electron optical elements. Additionally or alternatively, the insulating element is located between the electrical conductor 61 and one or more additional electron optical elements. The insulating element 70 may be located between the electrical conductor 61 and one or more electron optical elements of the stack.

[0147] like Fig.10 As shown, in one embodiment, the electrical conductors 61 can define field-free volumes 62 having axial directions that are parallel to each other (although in opposite directions). However, this is not necessarily the case. In alternative embodiments, multiple electrical conductors 61 are arranged so that their field-free volumes define different axial directions, such as angled or perpendicular axial directions. Fig.11 is a schematic plan view of an electronic optical component. The electrical insulator 70 is not Fig.11 The form of the electrical insulator 70 may be similar to, for example Fig. 9 or Fig.10 As shown in Fig.11 As shown, a plurality of electrical conductors 632 - 634 are arranged such that their field-free volumes 62 define different axial directions. Fig.11 The axial direction of the right electrical connector 60 (which is electrically connected to the board 710) may be perpendicular to Fig.11 The axial direction of other electrical connectors shown at the top and bottom. The electrical connectors 60 can be spaced apart from each other. Additionally or alternatively, multiple electrical conductors 632-634 can be positioned adjacent to each other. For example, multiple electrical conductors 632-634 can be positioned adjacent to each other in a substantially common axial direction or a close axial direction.

[0148] like Fig.11 As shown, each conductor 61 may be associated with an imaginary line 622-624 between the center 617-619 of the conductor and the center 715 of the aperture (or apertures 711) of the electron-optical element plate 710. Fig.11In the example, the first imaginary line 622 is located at Fig.11 The second imaginary line 623 is located between the center 617 of the conductor 632 shown at the top and the center 715 of the aperture (or apertures 711). Fig.11 The third imaginary line 624 is located between the center 618 of the conductor 633 on the right and the center 715 of the aperture. Fig.11 The center 619 of the conductor 634 shown at the bottom is between the center 715 of the aperture. The center 715 of the aperture can be the center of the plate 710. The center of the plate 710 can correspond to the path of the beam grid, such as the midpoint of the beam grid. Different conductors 61 can each have a center 617-619, and the center 617-619 corresponds to the center of the field-free volume defined by the conductor 61.

[0149] In one embodiment, the conductors 632-634 are arranged so that the minimum angle between any pair of imaginary lines 622-624 is at least 360° / 2N. N is the number of conductors 632-634. Fig.11 In the arrangement shown, there are three conductors 632-634. The conductors 632-634 are arranged so that the minimum angle between any pair of imaginary lines 622-624 is at least 360° / (2x3)=360° / 6=60°. Fig.11 As shown, the angle 625 between the first imaginary line 622 and the second imaginary line 623 is 90°, which is greater than 60°. The angle 626 between the second imaginary line 623 and the third imaginary line 624 is 90°, which is greater than 60°. The angle 627 between the third imaginary line 624 and the first imaginary line 622 is 180°, which is greater than 60°. In one embodiment, the conductors are arranged so that the angles between adjacent pairs of imaginary lines are equal. The conductors 61 can be evenly distributed around the aperture center 715 of the plate 710 of the electronic optical element. For example, for three conductors, the angle between the imaginary lines can be 120°. The conductors 632-634 can be equidistant from each other, or as shown, two of the conductors 632 and 634 can be equidistant from the third of the three conductors 633.

[0150] like Fig.11 As shown, in one embodiment, the axial direction of the conductors 632-634 is relative to the outer surface of the electron optical component. In one embodiment, the outer surface is the side of the electron optical component along the direction across the beam path. In one embodiment, the outer surface is orthogonal to the beam path. In one embodiment, the side of the electron optical component is a straight line shape. In one embodiment, the side of the electron optical component is a rectangular shape, such as a square. For example, in Fig.11In the arrangement shown, the stack has a generally square shape with rounded corners. In one embodiment, the electrical connectors 60 are positioned at different sides of the stack.

[0151] The stack does not necessarily have to have a rectangular shape. For example, in one embodiment, the stack can be circular, elliptical, triangular, pentagonal, hexagonal, heptagonal, octagonal or any other linear shape (e.g., rhombus). Note that a circular stack is conducive to thermal management, making the heat distribution across the cross section of the stack uniform. For example, when five electrical connectors 60 are provided, the stack can have a pentagonal shape so that each electrical connector 60 is arranged at a different side of the electronic optical component. Additionally or alternatively, when reading the plan view, one or more sides of the electronic optical component can have multiple electrical connectors associated therewith. The electrical connector can be arranged at the fillet of the stack. The shape of the stack can be regular or irregular, such as having sides of similar length or different lengths, or having a shape of two or more sides of the same length. The cross-sectional shape of the electronic optical component can be similar to the cross-sectional shape of the stack, so any shape of the stack disclosed herein can be adopted. However, the cross-sectional shapes of the stack and the electron-optical assembly need not be similar, as the cross-sectional shape of the electron-optical assembly includes insulating material 70 and / or a housing, which may have a different cross-sectional shape than the stack, for example because electrical conductors are incorporated into the cross-sectional shape of the electron-optical assembly while electrical conductors are not present in the stack. Even if the cross-sectional shapes of the stack and the electron-optical assembly are different, the same range of different cross-sectional shapes available for the stack can be provided for the electron-optical assembly.

[0152] As described above, in one embodiment, the surface covered by the electrical insulator 70 may face away from the electron optical element. Figure 7 As shown, in one embodiment, the surface 612 covered by the electrical insulator 70 faces away from the electron optical element in a direction parallel to the beam path. Figure 7 The beam path extends in the up-down direction (or the direction from upstream to downstream). The top of the electrical insulator 70 is located directly above the conductor 61, for example, in contact with the conductor 61, so that the electrical insulator 70 covers the uppermost surface of the conductor 61.

[0153] Additionally or alternatively, in one embodiment, the surface covered by the electrical insulator 70 faces away from the electron optical element in a direction across the beam path, desirably perpendicular to the beam path. Figure 7 or Figure 8 As shown, in one embodiment, the end surface 613 of the conductor 61 facing away from the electron optical element is covered by the insulating member 72 of the electrical insulator 70. Additionally or alternatively, in one embodiment, the electrical insulator 70 covers the inward surface 614 of the conductor 621, i.e., the surface facing the electron optical element.

[0154] Furthermore, two or more electrical connectors of the electron-optical assembly may be positioned at different locations relative to the stack along a direction parallel to the beam path, and / or two or more electrical connectors may be positioned at substantially the same location along a direction parallel to the beam path.

[0155] Although different embodiments and different arrangements are disclosed separately herein, such as different relative positioning of a single electrical connector 60 (and conductors 61) relative to a stack and the positioning of different electrical connectors 60 (and associated conductors 61) relative to the stack and to each other, the different variations may be combined in any reasonable manner.

[0156] In one embodiment, the electron-optical assembly 700 includes one or more electron-optical elements that include what may be referred to as micro-electromechanical components (although such components may not include moving or movable features), or may be manufactured using techniques suitable for manufacturing micro-electromechanical components (e.g., "MEMS technology"), some of which are designed to have electron-optical functions. The electron-optical assembly 700, or at least components of the electron-optical assembly 700, may be manufactured using such techniques. The electron-optical assembly 700 may include one or more elements that may be considered to be MEMS elements. During use, one or more such elements may be controlled to be set to a high potential difference relative to a reference potential (e.g., ground). Such elements may need to be precisely positioned (e.g., aligned) within the electron-optical assembly 700, such as relative to the path of the beam grid and relative to other electron-optical elements within the device (e.g., relative to the source, relative to the sample and / or the path of the beam grid). One embodiment of the present invention is expected to allow such elements to be more precisely positioned (e.g., aligned) within the stack of the electron-optical assembly 700, such as during operation, without deforming the electron-optical assembly 700 due to externally applied forces or moments. Embodiments of the invention may additionally or alternatively enable such elements to be more precisely positioned (eg, aligned) relative to other elements in device 40, thereby enabling stacks of electron-optical assemblies 700 within device 40 that include such elements to be more precisely positioned (eg, aligned).

[0157] As described above, in one embodiment, the electron optical assembly 700 is an electron optical lens assembly. The electron optical lens assembly may include an objective lens assembly. The electron optical lens assembly may be an objective lens assembly. In an alternative embodiment, the electron optical lens assembly is an electron optical converging lens assembly.

[0158] In one embodiment, the electron optical assembly 700 includes a collimator. For example, in one embodiment, the electron optical assembly 700 includes a magnetic collimator combined with an electrostatic capacitor lens array. The electron optical assembly 700 may include a single aperture lens array with one or two macro electrodes, which is placed away from the virtual source conjugate plane.

[0159] In an alternative embodiment, the electron optical assembly 700 includes a combination of a magnetic macro lens and an electrostatic slit deflector. The magnetic macro lens can be used for collimation. As a further alternative, in an embodiment, the electron optical assembly 700 includes a combined magnetic and electrostatic macro lens and a downstream slit deflector.

[0160] In general, the electron-optical assembly 700 can include any plates, such as detector array plates, lens electrode plates (in which multiple deflectors can be integrated), multiple deflector arrays, beam aperture arrays (e.g., upper beam aperture arrays and / or final beam limiting arrays), deflector arrays (e.g., strip deflector arrays), and other types of corrector elements.

[0161] The embodiments described herein mainly focus on a multi-beam electron optical device 40. The present invention is equally applicable to a single-beam electron optical device 40.

[0162] Although the present invention has been described in conjunction with various embodiments, other embodiments of the present invention will be apparent to those skilled in the art from the description and practice of the invention disclosed herein. For example, as described above, in one embodiment, the electronic optical assembly 700 includes an electrical connector 60. However, the electrical connector 60 of the present invention can be used anywhere in the electronic optical device 40 where electrical breakdown problems may exist. In one embodiment, the electronic optical device 40 includes an electrical connector 60 that is separate from the electronic optical assembly 700. For example, the electrical connector 60 can be located at a position where a low-force electrical connection is required to be made to other parts of the electronic optical device 40 (e.g., the body or frame of the electronic optical device 40). The electrical connector 60 can be located at a position where a particularly low-force electrical connection is not required. The electrical connector 60 can make the electronic optical device 40 more compact while providing a field-free volume. The description and examples should be regarded as exemplary only, and the true scope and spirit of the present invention are indicated by the appended claims.

[0163] The above description is intended to be illustrative rather than limiting. Therefore, those skilled in the art will appreciate that modifications may be made as described without departing from the scope of the following claims and clauses.

[0164] Clause 1. A charged particle optical assembly configured to direct a charged particle beam along a beam path toward a sample location, the charged particle optical assembly comprising:

[0165] a planar charged particle optical element configured to manipulate a charged particle beam along a beam path toward a sample location, the charged particle optical element comprising an aperture for the beam path; and

[0166] an electrical conductor electrically connected to the charged-particle optical element, wherein a groove is defined within the electrical conductor and the groove is configured to provide a field-free volume for inserting a high-voltage cable for electrically connecting the charged-particle optical element to a power source via an electrical coupler;

[0167] Wherein the electrical conductor comprises an electrical insulator spaced apart from the planar charged-particle optical element and providing at least a portion of a surface of the electrical conductor.

[0168] Clause 2. A charged particle optical component according to clause 1, wherein an end face of the electrical conductor comprises the at least a portion of the surface of the electrical conductor, wherein an opening to the field-free volume is defined in the end face.

[0169] Clause 3. A charged particle optical component according to clause 2, wherein the electrical insulator comprises an insulating member as the end face.

[0170] Clause 4. A charged particle optical component according to clause 3, wherein the insulating member comprises an insulating plug, which comprises the end face of the electrical conductor and optionally extends through the opening to provide at least a portion of the surface of the groove, desirably extending into the field-free volume.

[0171] Clause 5. A charged particle optical component according to any one of clauses 2 to 4, wherein an electrical insulator extends from the end face into the field-free volume so as to provide a portion of the internal surface of the electrical conductor, preferably a portion of the internal surface away from the charged particle optical element, preferably the internal surface defining the field-free volume.

[0172] Clause 6. A charged particle optical component according to any preceding clause, wherein at least a portion of the electrical insulator surrounds a cross section of the electrical conductor.

[0173] Clause 7. A charged particle optical component according to any of the preceding clauses, comprising a plurality of electrical conductors electrically connected to one or more charged particle optical elements of the charged particle optical component.

[0174] Clause 8. A charged particle optical component according to clause 7, wherein the electrical insulator comprises at least a portion of a surface common to the plurality of electrical conductors and / or the electrical insulator is common to the plurality of electrical conductors.

[0175] Clause 9. A charged particle optical component according to clause 8, wherein the electrical insulator further comprises a continuous volume between the plurality of electrical conductors, desirably the electrical insulator provides the surface common to the plurality of electrical conductors.

[0176] Clause 10. A charged particle optical component according to any one of clauses 7 to 9, wherein two of the electrical conductors are arranged such that the beam path is located between them.

[0177] Clause 11. A charged particle optical component according to any one of clauses 7 to 10, wherein the plurality of electrical conductors are arranged such that their field-free volumes define different axial directions.

[0178] Clause 12. A charged particle optical component according to any one of clauses 7 to 11, wherein the plurality of electrical conductors are desirably positioned adjacent to each other in a substantially common axial direction or a close axial direction.

[0179] Item 13. A charged particle optical component according to any one of items 7 to 12, wherein each of the conductors is associated with an imaginary line between the center of the conductor and the center of the plurality of apertures, and the conductors are arranged so that the minimum angle between any pair of the imaginary lines is at least 360° / 2N, where N is the number of conductors, the axial direction is desirably relative to an outer surface of the charged particle optical component, the outer surface is desirably a side of the charged particle optical component in a direction across the beam path, desirably orthogonal to the beam path, and the side is desirably a rectilinear shape, such as a rectangle, for example, a square.

[0180] Clause 14. A charged particle optical component according to any of the preceding clauses, wherein the conductor includes a conductive element, the surface of the groove includes the surface of the conductive element, wherein the electrical insulator of the conductor is thicker than the conductive element, the conductive element is desirably located within the electrical insulator, and the conductive element may include, for example, a conductive layer on the electrical insulator.

[0181] Clause 15. A charged particle optical component according to any of the preceding clauses, wherein the electrical insulator of the electrical conductor is expected to extend toward one or more additional charged particle optical elements configured to operate the charged particle beam, and / or the insulating element is located between the electrical conductor and the one or more additional charged particle optical elements.

[0182] Clause 16. A charged particle optical component according to any of the preceding clauses, wherein the surface of the electrical insulator faces away from the charged particle optical element in a direction parallel to the path of the charged particle beam.

[0183] Clause 17. A charged particle optical component according to any of the preceding clauses, wherein the surface of the electrical insulator faces away from the charged particle optical element in a direction across the path of the charged particle beam.

[0184] Clause 18. A charged particle optical component according to any of the preceding clauses, wherein the charged particle beam comprises a plurality of beams along the beam path, and desirably, the charged particle optical element comprises a plurality of apertures, individual apertures being used for respective beams of the plurality of beams.

[0185] Item 19. A charged particle optical component configured to direct multiple charged particle beams along a beam path toward a sample position, the charged particle optical component comprising: a planar charged particle optical element configured to operate on a charged particle beam along the beam path toward a sample position, the charged particle optical element comprising an aperture for the beam path; and a conductor electrically connected to the charged particle optical element, wherein a groove is defined within the conductor, and the groove is configured to provide a field-free volume for inserting a high-voltage cable, the high-voltage cable being used to electrically connect the charged particle optical element to a power source via an electrical coupler; wherein an electrical insulator covers at least a portion of a surface of the conductor, the surface facing away from the charged particle optical element.

[0186] Clause 20. A charged particle optical component according to Clause 19, wherein the electrical insulator covers an end face of the electrical conductor, wherein an opening to the field-free volume is defined in the end face.

[0187] Clause 21. A charged particle optical component according to Clause 20, wherein the electrical insulator at the end face comprises an insulating member covering the end face of the electrical conductor.

[0188] Clause 22. The charged particle optical component of Clause 21, wherein the insulating member is an insulating plug engaged with the end surface of the electrical conductor.

[0189] Clause 23. A charged particle optical component according to any one of clauses 20 to 22, wherein the electrical insulator desirably extends into the field-free volume, covering a portion of an inner surface of the electrical conductor, the inner surface defining the field-free volume, in addition to covering the end face.

[0190] Clause 24. A charged particle optical component according to any one of clauses 19 to 23, wherein at least a portion of the electrical insulator surrounds a cross section of the electrical conductor.

[0191] Clause 25. The charged particle optical component of any one of clauses 19 to 24, comprising a plurality of electrical conductors electrically connected to one or more charged particle optical elements of the charged particle optical component.

[0192] Clause 26. The charged-particle optical component of Clause 25, wherein the electrical insulator covers at least a portion of a surface of the plurality of electrical conductors.

[0193] Clause 27. A charged particle optical component according to Clause 26, wherein the electrical insulator comprises a continuous volume between the surfaces of the electrical conductor covered by the electrical insulator.

[0194] Clause 28. A charged particle optical component according to any one of clauses 25 to 27, wherein two of the electrical conductors are arranged with the beam path between them.

[0195] Clause 29. A charged particle optical component according to any one of clauses 25 to 28, wherein the plurality of electrical conductors are arranged such that their field-free volumes define different axial directions.

[0196] Clause 30. A charged particle optical component according to any one of clauses 25 to 29, wherein the plurality of electrical conductors are desirably positioned adjacent to each other in a substantially common axial direction or a close axial direction.

[0197] Clause 31. A charged particle optical component according to any of clauses 25 to 30, wherein each of the conductors is associated with an imaginary line between the center of the conductor and the center of the aperture, and the conductors are arranged so that the minimum angle between any pair of the imaginary lines is at least 360° / 2N, where N is the number of conductors.

[0198] Clause 32. A charged particle optical component according to any one of clauses 19 to 31, wherein, where the electrical insulator covers a surface of the electrical conductor, the electrical insulator is thicker than the electrical conductor, for example in a direction away from the axial direction of the field-free volume.

[0199] Clause 33. A charged particle optical component according to any one of clauses 19 to 32, wherein the electrical insulator extends between the electrical conductor and one or more further charged particle optical elements, the one or more further charged particle optical elements being configured to operate on the charged particle beam.

[0200] Clause 34. A charged particle optical component according to any one of clauses 19 to 33, wherein the surface covered by the electrical insulator faces away from the charged particle optical element in a direction parallel to the beam path.

[0201] Clause 35. A charged particle optical component according to any one of clauses 19 to 34, wherein the surface covered by the electrical insulator faces away from the charged particle optical element in a direction across the beam path, desirably in a direction across the path of the charged particle beam.

[0202] Clause 36. A charged particle optical component according to any of the preceding clauses, wherein the field-free volume defines an axial direction at a distance from a plane of the planar charged particle optical element.

[0203] Clause 37. A charged particle optical component according to any of the preceding clauses, wherein the field-free volume defines an axial direction that is at a certain angle relative to the plane of the planar charged particle optical element, for example, at a certain angle that deviates outward from the plane of the planar charged particle optical element.

[0204] Clause 38. A charged particle optical component according to any of the preceding clauses, comprising an isolator configured to: support and electrically isolate the charged particle optical element and be located remote from the beam path.

[0205] Clause 39. A charged particle optical device for projecting a plurality of charged particle beams along respective beam paths towards a sample location, the charged particle optical device comprising: one or more charged particle optical components according to any of the preceding clauses.

[0206] Clause 40. A charged particle optical apparatus comprising: a charged particle optical assembly according to any one of clauses 1 to 38 or a charged particle optical device according to clause 39; and an actuatable stage configured to support a sample.

[0207] Item 41. A method for electrically insulating a conductor of a charged particle optical component, wherein the conductor is configured to direct a charged particle beam toward a sample location, the method comprising: covering at least a portion of a surface of the conductor with one or more electrical insulators, the surface facing away from a planar charged particle optical element electrically connected to the conductor, the charged particle optical element being configured to operate a charged particle beam along a beam path and including an aperture for the beam path, wherein a groove is defined within the conductor and the groove is configured to provide a field-free volume for inserting a high voltage cable, the high voltage cable being used to electrically connect the charged particle optical element to a power source via an electrical coupler.

[0208] Item 42. A method for electrically insulating a conductor of a charged particle optical component, wherein the conductor is configured to direct a charged particle beam along a beam path to a sample position, the charged particle optical component comprising a planar charged particle optical element for operating the charged particle beam, the method comprising: having a conductor, the conductor having a conductive concave surface with a groove of the conductor, the conductor comprising an electrical insulator spaced apart from the planar charged particle optical element, the planar charged particle optical element being electrically connected to the conductor, wherein the groove is configured within the conductor to provide a field-free volume for inserting a high-voltage cable, for electrically connecting the charged particle optical element to a power source via an electrical coupler between the conductor and the high-voltage cable.

[0209] Item 43. A charged particle optical component configured to direct multiple charged particle beams along a beam path toward a sample position, the charged particle optical component comprising: a planar charged particle optical element configured to operate the charged particle beam along the beam path toward the sample with a voltage, the charged particle optical element comprising an aperture for the beam path; and a conductor electrically connected to the charged particle optical element, wherein a groove is defined within the conductor and is configured to provide a field-free volume for inserting a high-voltage cable for electrically coupling the charged particle optical element to a power source via an electrical coupler; wherein the conductor comprises an electrical insulator, the electrical insulator comprising at least an end face of the conductor and an extension surface extending from the end face into the groove.

Claims

1. A charged particle optical assembly configured to direct a charged particle beam along a beam path to a sample location, the charged particle optical assembly comprising: a planar charged particle optical element configured to manipulate a charged particle beam along a beam path toward a sample location, the charged particle optical element comprising an aperture for the beam path; and an electrical conductor electrically connected to the charged-particle optical element, wherein the recess is defined within the electrical conductor and the recess is configured to provide a field-free volume for inserting a high-voltage cable for electrically connecting the charged-particle optical element to a power source via an electrical coupler; Wherein the electrical conductor comprises an electrical insulator spaced apart from the planar charged-particle optical element and providing at least a portion of a surface of the electrical conductor. 2 . The charged particle optical component of claim 1 , wherein an end face of the electrical conductor comprises the at least a portion of the surface of the electrical conductor, wherein an opening to the field-free volume is defined in the end face. 3 . The charged particle optical component according to claim 2 , wherein the electrical insulator comprises an insulating member as the end surface.

4. A charged particle optical component according to claim 3, wherein the insulating member comprises an insulating plug, which includes the end face of the electrical conductor and optionally extends through the opening to provide at least a portion of the surface of the groove, desirably extending into the field-free volume.

5. A charged particle optical component according to any one of claims 2 to 4, wherein an electrical insulator extends from the end face into the field-free volume so as to provide a portion of the internal surface of the electrical conductor, preferably a portion of the internal surface away from the charged particle optical element, and preferably the internal surface defines the field-free volume.

6. A charged particle optical component according to any one of the preceding claims, wherein at least a portion of the electrical insulator surrounds a cross section of the electrical conductor.

7. A charged particle optical component according to any one of the preceding claims, comprising a plurality of electrical conductors electrically connected to one or more charged particle optical elements of the charged particle optical component.

8. A charged particle optical component according to claim 7, wherein the electrical insulator comprises at least a portion of a surface common to the plurality of electrical conductors and / or the electrical insulator is common to the plurality of electrical conductors.

9. A charged particle optical component according to claim 8, wherein the electrical insulator further comprises a continuous volume between the plurality of electrical conductors, desirably the electrical insulator providing the surface common to the plurality of electrical conductors.

10. A charged particle optical component according to any one of claims 7 to 9, wherein at least one of the following: a. Two of the conductors are arranged so that the beam path is located between them; b. the plurality of electrical conductors are arranged such that their field-free volumes define different axial directions; and c. The plurality of electrical conductors are desirably positioned adjacent to each other in a substantially common axial direction or in a close axial direction.

11. A charged particle optical component according to any of the preceding claims, wherein the conductor comprises a conductive element, the surface of the groove comprises the surface of the conductive element, wherein the electrical insulator of the conductor is thicker than the conductive element, the conductive element is desirably located within the electrical insulator, and the conductive element may comprise, for example, a conductive layer on the electrical insulator.

12. A charged particle optical component according to any of the preceding claims, wherein the electrical insulator of the electrical conductor is expected to extend toward one or more additional charged particle optical elements configured to operate the charged particle beam, and / or the insulating element is located between the electrical conductor and the one or more additional charged particle optical elements.

13. A charged particle optical component according to any one of the preceding claims, wherein the surface of the electrical insulator faces away from the charged particle optical element in a direction parallel to the path of the charged particle beam.

14. A charged particle optical component according to any one of the preceding claims, wherein the surface of the electrical insulator faces away from the charged particle optical element in a direction across the path of the charged particle beam.

15. A charged particle optical component according to any one of the preceding claims, wherein the charged particle beam comprises a plurality of beams along the beam path, and desirably the charged particle optical element comprises a plurality of apertures, individual apertures being used for respective ones of the plurality of beams.

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