Assessment system, method of assessing

Abstract

This invention discloses an evaluation system and method. In one configuration, charged particles are guided toward a sample in a sub-beam configured in a multi-beam configuration. A plurality of control electrodes define a control lens array. Each control lens in the control lens array is aligned with and configured to operate on a specific sub-beam of the multi-beam configuration. A plurality of objective lens electrodes define an objective lens array that guides the sub-beams onto a sample. The objective lens is aligned with a sub-beam path, which is aligned with a specific control lens. Selectable landing energy is applied for one sub-beam of the multi-beam configuration by applying corresponding potentials to the control electrodes and the objective lens electrodes. A controller is configured to select the corresponding potentials, so that a spatial relationship between an image plane of the system and all control electrodes and objective lens electrodes is the same for each selectable landing energy.

Description

Technical Field

[0001] The embodiments provided herein relate to an evaluation system and method for evaluating a sample using charged particles (particularly electrons), for example by detecting signal electrons emitted from the sample. Prior Technology

[0002] When manufacturing semiconductor integrated circuit (IC) chips, undesirable pattern defects, such as those caused by optical effects and stray particles, inevitably appear on the substrate (i.e., the wafer) or mask during the manufacturing process, thereby reducing yield. Monitoring the extent of these undesirable pattern defects is therefore a crucial process in IC chip manufacturing. More generally, the inspection and / or measurement of the surface of substrates or other objects / materials are important processes during and / or after their manufacturing.

[0003] Pattern detection tools using charged particle beams have been used to inspect objects (which may be called samples), for example, to detect pattern defects. These tools typically employ electron microscopy techniques, such as scanning electron microscopy (SEM). In SEM, a primary electron beam, directed at relatively high energies using a final deceleration step, is brought to the sample with a relatively low landing energy. The electron beam is focused as a probe spot on the sample. The interaction between the material structure at the probe spot and the landing electrons from the electron beam causes signal electrons, such as secondary electrons, backscattered electrons, or Auger electrons, to be emitted from the surface. These signal electrons can be emitted from the material structure of the sample. By scanning the sample surface with the primary electron beam as a probe spot, signal electrons can be emitted across the sample surface. By collecting these emitted signal electrons from the sample surface, the pattern detection tool can obtain an image representing the characteristics of the material structure of the sample surface.

[0004] Generally, improvements are needed in the control of charged particle beams within the evaluation system and methods. Summary of the Invention

[0005] One objective of this invention is to improve the control of charged particle beams in evaluation systems and methods.

[0006] According to one aspect of the present invention, an evaluation system is provided for guiding charged particles in a sub-beam configured in a multi-beam configuration toward a sample. The system comprises: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being aligned with and configured to operate on a sub-beam of a respective sub-beam of the multi-beam configuration; a plurality of objective lens electrodes defining and configured to guide the sub-beams onto a sample, each objective lens in the objective lens array being aligned with a sub-beam path, the sub-beam path being aligned with a respective control lens; and a controller configured to apply a plurality of selectable landing energies to a sub-beam of the multi-beam configuration by applying corresponding potentials to the control electrodes and the objective lens electrodes, wherein: the controller is configured to select the corresponding potentials such that a spatial relationship between an image plane of the system and all the control electrodes and objective lens electrodes is the same for each of the selectable landing energies. Simple Explanation of the Diagram

[0007] The above and other aspects of the present invention will become more apparent from the description of the exemplary embodiments obtained in conjunction with the accompanying drawings.

[0008] [picture] [1] A schematic diagram illustrating an illustrative charged particle beam detection device is shown.

[0009] [picture] [2] To illustrate as [picture] [1] is a schematic diagram of an exemplary multi-beam device of an exemplary charged particle beam detection device.

[0010] [picture] [3] is a schematic diagram of an exemplary electro-optic column containing a condenser lens array.

[0011] [picture] [4] is a curve of landing energy versus resolution for an illustrative configuration.

[0012] [picture] [5] is an enlarged view of the objective lens and control lens.

[0013] [picture] [6] is a schematic cross-sectional view of a portion of an objective array as an example configuration.

[0014] [picture] [7] is [picture] [6] A bottom view of part of the objective lens array.

[0015] [picture] [8] for [picture] [6] A modified bottom view of part of the objective array.

[0016] [picture] [9] for inclusion [picture] [6] A magnified schematic cross-sectional view of the detector in the objective lens.

[0017] [picture]

[10] is a schematic diagram of an exemplary electro-optic column containing a giant collimator and a giant scanning deflector.

[0018] [picture]

[11] A schematic cross-sectional view of the control lens array and objective lens array of the evaluation system.

[0019] [picture]

[12] is a curve of beam current versus resolution, which shows the curve of minimum resolution for two different landing energies. [ ]

[0020] [picture]

[13] for [picture]

[12] The graph further shows the landing energy stepping from 2.5 keV to 1 keV at a fixed image plane and at the minimum resolution for each of the eight different entity configurations of the system. [ ]

[0021] [picture]

[14] for [picture]

[13] The curve extends to a landing energy of 0.5 keV. [ ]

[0022] [picture]

[15] To show the resolution performance as a function of landing energy when the image plane is fixed, compared to the case where the image plane is movable. [ ]

[0023] [picture]

[16] for [picture]

[13] The curve of step landing energy at a fixed image plane position is shown for one of the physical configurations of the system, and the additional curve shows the change of beam current achieved by controlling the reduction rate. Implementation

[0024] Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings, wherein, unless otherwise indicated, the same numbers in different figures denote the same or similar elements. The embodiments set forth in the following description of the exemplary embodiments do not represent all embodiments of the invention. Instead, they are merely examples of apparatuses and methods conforming to the nature of the invention as described in the appended claims.

[0025] Enhanced computing power in electronic devices can be achieved by significantly increasing the packing density of circuit components (such as transistors, capacitors, diodes, etc.) on IC chips, thereby reducing the physical size of the devices. This has been achieved through increased resolution, enabling the fabrication of smaller structures. For example, an IC chip in a smartphone (about the size of a thumbnail and available in 2019 or earlier) could include more than 2 billion transistors, each smaller than 1 / 1000th the size of a human hair. Therefore, it is not surprising that semiconductor IC manufacturing involves a complex and time-consuming process with hundreds of individual steps. Even an error in one step can significantly affect the functionality of the final product. Even a "fatal defect" can cause device failure. The goal of the manufacturing process is to improve the overall yield of the process. For example, to achieve a 75% yield for a 50-step process (where steps can indicate the number of layers formed on the wafer), each individual step must have a yield greater than 99.4%. If each individual step has a yield of 95%, the overall process yield will be as low as 7%.

[0026] While high process yields are desirable in IC chip manufacturing facilities, maintaining high substrate (i.e., wafer) throughput (defined as the number of substrates processed per hour) is also essential. Both high process yields and high substrate throughput can be affected by the presence of defects. This is especially true if operator intervention is required to inspect for defects. Therefore, high-throughput detection and identification of micron and nanometer-scale defects using inspection tools such as scanning electron microscopes ("SEM") are crucial for maintaining high yields and low costs.

[0027] SEM comprises scanning devices and detector devices. The scanning devices include: an illumination device containing an electron source for generating primary electrons; and a projection device for scanning a sample, such as a substrate, using one or more focused primary electron beams. At least the illumination device or system and the projection device or system can be collectively referred to as an electro-optical system or apparatus. Primary electrons interact with the sample, generating secondary electrons. The detector captures these secondary electrons from the sample while scanning, allowing the SEM to produce an image of the scanned area of ​​the sample. For high-volume inspection, some detector devices use multiple focused primary electron beams, i.e., multi-beams. The constituent beams of a multi-beam system can be called sub-beams or fine beams. Multi-beam systems can scan different portions of the sample simultaneously. Multi-beam detection devices can therefore inspect samples at much higher speeds than single-beam detection devices.

[0028] The following describes the implementation of a known multi-beam detection device.

[0029] The figures are schematic. Therefore, for clarity, the relative dimensions of the components in the figures are exaggerated. In the following description of the figures, the same or similar reference numerals refer to the same or similar components or entities, and only the differences with respect to individual embodiments are described. Although this specification and figures are directed to electro-optical devices, it should be understood that the embodiments are not intended to limit the invention to specific charged particles. Therefore, more generally, references to electrons throughout the present invention can be considered as references to charged particles, which are not necessarily electrons.

[0030] Now for reference [picture] [1] This is a schematic diagram of an illustrative charged particle beam detection device 100, which can also be called a charged particle beam evaluation system or simply an evaluation system. [picture] [1] The charged particle beam detection device 100 includes a main chamber 10, a loading and locking chamber 20, an electron beam tool 40, an equipment front-end module (EFEM) 30, and a controller 50. The electron beam tool 40 is located in the main chamber 10.

[0031] EFEM 30 includes a first loading port 30a and a second loading port 30b. EFEM 30 may include additional loading ports. The first loading port 30a and the second loading port 30b may, for example, receive a front-opening unit cassette (FOUP) containing a substrate to be tested (e.g., a semiconductor substrate or a substrate made of other materials) or a sample (the substrate, wafer, and sample are collectively referred to as "sample" below). One or more robotic arms (not shown) in EFEM 30 transport the sample to the loading locking chamber 20.

[0032] Loading-lock chamber 20 is used to remove gas surrounding the sample. This creates a vacuum, meaning the local gas pressure is lower than the ambient pressure. Loading-lock chamber 20 can be connected to a loading-lock vacuum pump system (not shown), which removes gas particles from loading-lock chamber 20. Operation of the loading-lock vacuum pump system allows the loading-lock chamber to reach a first pressure below atmospheric pressure. After reaching the first pressure, one or more robotic arms (not shown) transport the sample from loading-lock chamber 20 to main chamber 10. Main chamber 10 is connected to a main chamber vacuum pump system (not shown). The main chamber vacuum pump system removes gas particles from main chamber 10, causing the pressure around the sample to reach a second pressure below the first pressure. After reaching the second pressure, the sample is transported to an electron beam tool 40 for sample detection. Electron beam tool 40 may include multi-beam electro-optical devices.

[0033] The controller 50 is electronically connected to the electron beam tool 40. The controller 50 may be a processor (such as a computer) configured to control the charged particle beam detection device 100. The controller 50 may also include a processing circuitry configured to perform various signal and image processing functions. Although the controller 50 is... [picture] [1] is shown as being outside a structure including the main chamber 10, the loading and locking chamber 20, and the EFEM 30, but it should be understood that the controller 50 may be part of that structure. The controller 50 may be located in one of the components of the charged particle beam detection device or may be distributed above at least two of the components. While the present invention provides an example of a main chamber 10 for housing an electron beam detection tool, it should be noted that the nature of the invention is not limited in its broadest sense to a chamber for housing an electron beam detection tool. In fact, it should be understood that the foregoing principles may also be applied to other tools and other configurations of a device operating under a second pressure.

[0034] Now for reference [picture] [2], which is a schematic diagram of an illustrative electron beam tool 40, the illustrative electron beam tool including as [picture] [1] The exemplary charged particle beam detection apparatus 100 includes a multi-beam detection tool. The multi-beam electron beam tool 40 (also referred to herein as apparatus 40) includes an electron source 201, a projection device 230, a motorized stage 209, and a sample holder 207. The electron source 201 and the projection device 230 may be collectively referred to as an illumination device. The sample holder 207 is supported by the motorized stage 209 to hold a sample 208 (e.g., a substrate or mask) for detection. The multi-beam electron beam tool 40 further includes an electron detection device 240.

[0035] The electron source 201 may include a cathode (not shown) and an extractor or anode (not shown). During operation, the electron source 201 is configured to emit electrons from the cathode as primary electrons. The primary electrons are extracted or accelerated by the extractor and / or anode to form a primary electron beam 202.

[0036] The projection device 230 is configured to convert the primary electron beam 202 into a plurality of sub-beams 211, 212, 213 and to direct each sub-beam onto the sample 208. Although three sub-beams are shown for simplicity, there may be tens, hundreds, thousands, tens of thousands, or even hundreds of thousands (or more) of sub-beams. These sub-beams may be referred to as fine beams.

[0037] Controller 50 can be connected to [picture] [1] Various components of the charged particle beam detection device 100, such as the electron source 201, the electron detection device 240, the projection device 230, and the motorized stage 209. The controller 50 can perform various image and signal processing functions. The controller 50 can also generate various control signals to control the operation of the charged particle beam detection device (including the charged particle multi-beam device).

[0038] Projection device 230 can be configured to focus sub-beams 211, 212, and 213 onto sample 208 for detection and can form three detection spots 221, 222, and 223 on the surface of sample 208. Projection device 230 can be configured to deflect primary sub-beams 211, 212, and 213 so that detection spots 221, 222, and 223 scan individual scanning areas across segments of the surface of sample 208. In response to the primary sub-beams 211, 212, and 213 incident on the detection spots 221, 222, and 223 on sample 208, electrons are generated from sample 208. These electrons include secondary electrons and backscattered electrons, which can be referred to as signal particles. Secondary electrons typically have an electron energy of ≤ 50 eV, and backscattered electrons typically have an electron energy between 50 eV and the landing energy of primary sub-beams 211, 212, and 213.

[0039] The electron detection device 240 is configured to detect secondary electrons and / or backscattered electrons and generate corresponding signals. These signals are sent to the controller 50 or a signal processing system (not shown) to construct, for example, an image of the corresponding scanned area of ​​sample 208. The electron detection device may be integrated into or separated from the projection device, wherein a secondary optical column is provided to guide secondary electrons and / or backscattered electrons to the electron detection device.

[0040] The controller 50 may include an image processing system comprising an image acquisition unit (not shown) and a storage device (not shown). For example, the controller may include a processor, computer, server, mainframe computer, terminal, personal computer, any type of mobile computing device, and the like, or combinations thereof. The image acquisition unit may include at least a portion of the controller's processing capabilities. Therefore, the image acquisition unit may include at least one or more processors. The image acquisition unit may be communicatively coupled to the electronic detection device 240 of the device 40 to allow signal communication, such as electrical conductors, fiber optic cables, portable storage media, IR, Bluetooth, the Internet, wireless networks, radio waves, and others, or combinations thereof. The image acquisition unit may receive signals from the electronic detection device 240, process the data contained in the signals, and construct an image based on the data. The image acquisition unit may thus acquire an image of sample 208. The image acquisition unit may also perform various post-processing functions, such as generating contours, overlaying indicators onto the acquired image, and the like. The image acquisition unit can be configured to adjust the brightness and contrast of the acquired image. The storage device can be a storage medium such as a hard drive, USB flash drive, cloud storage, random access memory (RAM), other types of computer-readable memory, and the like. The storage device can be coupled to the image acquisition unit and can be used to store scanned raw image data as raw images and post-processed images.

[0041] The image acquisition unit can acquire one or more images of a sample based on imaging signals received from the electronic detection device 240. The imaging signals may correspond to a scanning operation used for imaging charged particles. The acquired image may be a single image comprising a plurality of imaging regions. This single image can be stored in a memory. The single image may be an original image that can be divided into a plurality of regions. Each of these regions may contain an imaging region containing the features of sample 208. The acquired image may comprise multiple images of a single imaging region of sample 208 sampled multiple times over a period of time. These multiple images can be stored in a memory. The controller 50 can be configured to perform image processing steps using multiple images of the same location of sample 208.

[0042] The controller 50 may include a measurement circuitry (e.g., an analog-to-digital converter) to obtain the distribution of detected secondary electrons. Electron distribution data collected during the detection time window can be combined with corresponding scan path data from each of the primary sub-beams 211, 212, and 213 incident on the sample surface to reconstruct an image of the structure of the sample under test. The reconstructed image can be used to reveal various features of the internal or external structure of sample 208. The reconstructed image can also be used to reveal any defects that may exist in the sample.

[0043] The controller 50 controls the motorized stage 209 to move the sample 208 during the detection of the sample 208. The controller 50 enables the motorized stage 209 to move the sample 208 in one direction (preferably continuously) at least during the sample detection period, for example, at a constant speed. The controller 50 controls the movement of the motorized stage 209 such that it varies the speed of movement of the sample 208 depending on various parameters. For example, the controller may control the stage speed (including its direction) depending on the characteristics of the detection step and / or scanning procedure, as disclosed in EPA 21171877.0 filed May 3, 2021, which is hereby incorporated with respect to at least a combination of stepping and scanning strategies for the stage.

[0044] [picture] [3] is a schematic diagram of an exemplary electro-optical column used for evaluating the system. For ease of illustration, the lens array is schematically depicted herein by an array of elliptical shapes. Each elliptical shape represents one of the lenses in the lens array. By convention, elliptical shapes are used to represent lenses, similar to the biconvex form often used in optical lenses. However, in the context of charged particle configurations such as those discussed herein, it should be understood that the lens array will generally operate electrostatically and therefore may not require any physical element with a biconvex shape. Instead, as described below, the lens array may comprise multiple plates with apertures. Each plate with an aperture may be referred to as an electrode. Electrodes may be provided in series along the sub-beam paths of the multi-beam sub-beams.

[0045] An electron source 201 directs electrons toward an array of condenser lenses 231 that form part of the projection system 230. The electron source is ideally a high-brightness thermal field emitter with a good trade-off between brightness and total emission current. There may be tens, hundreds, or thousands of condenser lenses 231. The condenser lenses of the array 231 may comprise multi-electrode lenses and have a construction based on EP1602121A1, which is hereby incorporated by reference in particular to the disclosure of a lens array for splitting an electron beam into a plurality of sub-beams, wherein the array provides a lens for each sub-beam. The condenser lens array may take the form of at least two plates, preferably three plates, which act as electrodes, wherein the apertures in each plate are aligned with each other and correspond to the positions of the sub-beams. During operation, at least two of the plates are maintained at different potentials to achieve the desired lensing effect. Between the plates of the condenser lens array are electrically insulating plates made of insulating materials such as ceramic or glass, having one or more apertures for the sub-beams. In an alternative configuration, one or more of the plates may be characterized by apertures, each aperture having its own electrode, each aperture having an electrode array around its periphery, or arranged as a group of apertures having a common electrode.

[0046] In one configuration, the condenser lens array is formed by three plate arrays in which charged particles have the same energy upon entering and exiting each lens; this configuration can be called a single lens. Therefore, dispersion occurs only within the single lens itself (between the entry and exit electrodes), thereby limiting off-axis chromatic aberration. When the condenser lens is thin, such as a few millimeters, this type of aberration has a small or negligible effect.

[0047] Each focusing lens in the array directs electrons into individual sub-beams 211, 212, 213, which are focused at their respective intermediate focal points 233. Collimators or collimator arrays can be positioned to operate on the respective intermediate focal points 233. The collimator can take the form of a deflector 235 provided at the intermediate focal point 233. The deflector 235 is configured to bend the individual sub-beams 211, 212, 213 by a certain amount to effectively ensure that the main beam (which may also be referred to as the beam axis) is substantially perpendicular to the sample 208 (i.e., substantially at 90° to the nominal surface of the sample).

[0048] Below the deflector 235 (i.e., in the downstream direction or further away from the source 201), there is a control lens array 250, which includes control lenses 251 for each sub-beam 211, 212, 213. The control lens array 250 may include two or more (preferably at least three) plate electrode arrays connected to the respective potential sources, preferably wherein an insulating plate contacts the electrodes, for example, between the electrodes. Each of the plate electrode arrays may be referred to as a control electrode. The function of the control lens array 250 is to optimize the beam angle relative to the beam reduction rate and / or control the beam energy delivered to the objective lens 234, each of which guides the respective sub-beams 211, 212, 213 onto the sample 208.

[0049] As needed, an array of scan deflectors 260 is provided between the control lens array 250 and the array of objectives 234 (objective array). The array of scan deflectors 260 includes a scan deflector for each sub-beam 211, 212, 213. Each scan deflector is configured to deflect the respective sub-beam 211, 212, 213 in one or both directions so that the sub-beam scans across the sample 208 in one or both directions.

[0050] A detector module 402 is provided within or between the objective lens 234 and the sample 208 to detect signal electrons / particles emitted from the sample 208. An exemplary configuration of this detector module 402 is described below. It should be noted that the detector may additionally or alternatively have detector elements in the countercurrent direction along the primary beam path of the objective lens array or even the control lens array.

[0051] [picture] [3] The system is configured to control the landing energy of electrons on a sample by changing the potential of electrodes applied to the control lens and objective lens. The control lens and objective lens work together and can be referred to as the objective lens assembly. Depending on the nature of the sample being evaluated, the landing energy can be selected to increase the emission and detection of secondary electrons. The controller can be configured to control the landing energy to any desired value or one of a plurality of desired values ​​within a predetermined range. In one embodiment, the landing energy can be controlled to a desired value within, for example, a predetermined range of 1000 eV to 5000 eV. [picture] [4] To plot the resolution as a function of landing energy, it is assumed that the beam angle / reduction rate is reoptimized to change the landing energy. As can be seen, the resolution of the evaluation tool remains substantially constant as the change in landing energy is reduced to a minimum value LE_min. Resolution deteriorates below LE_min because it is necessary to reduce the lens strength of the objective and the electric field within the objective in order to maintain a minimum distance between the objective and / or the detector and the sample. As discussed further below, interchangeable modules can also be used to change or control the landing energy.

[0052] Note here that, if along [picture] The "resolution" depicted on the horizontal or x-axis of the graph in [4] is the smallest resolvable size (e.g., size) of the sub-beam at the sample location. Resolution (e.g., along the x-axis) has a distance unit, such as a value in nanometers. Typically, the beam shape is close to Gaussian. A common definition of the size or resolution of this beam with a Gaussian profile is the diameter of the beam containing fifty percent (50%) of the current (which may be called a two-dimensional FW50). Another common definition is the distance between the first and third quartiles or the twenty-fifth (25%) and seventy-five percent (75%) intensity levels when the beam is scanned across the edges (which may be called a one-dimensional FW50). These definitions are expressed in distance units. They can be converted to each other by multiplying by a scaling factor, assuming the existence of a Gaussian beam shape. It should be noted that these measurements are performed on the primary beam before signal particles are generated, let alone detected. Therefore, the reference to resolution as disclosed herein is independent of image resolution and therefore independent of pixel size. For the avoidance of doubt, in the terminology used herein, resolution is defined as the resolution of a beam; the minimum resolvable size of a beam at the surface of a sample.

[0053] Ideally, landing energy is varied primarily by controlling the energy of electrons leaving the control lens. The potential difference within the objective lens is preferably kept constant during this variation, keeping the electric field within the objective lens as high as possible. Additionally, the potential applied to the control lens can be used to optimize the beam angle and reduction ratio. The control lens can also be called a refocusing lens because it can be used to correct the focus position in response to changes in landing energy. Ideally, each control lens contains three electrodes to provide two independent control variables, as discussed further below. For example, one of the electrodes can be used to control the reduction ratio, while the other electrodes can be used to independently control the landing energy. Alternatively, each control lens may have only two electrodes. In contrast, when only two electrodes are present, one of the electrodes may need to control both the reduction ratio and the landing energy.

[0054] [picture] [5] is an enlarged schematic diagram of an objective lens 300 of an objective lens array and a control lens 600 of a control lens array 250. The objective lens 300 can be configured to reduce the electron beam by more than 10 times, ideally in the range of 50 to 100 or greater. The objective lens includes a middle or first electrode 301, a lower or second electrode 302, and an upper or third electrode 303. Voltage sources V1, V2, and V3 are configured to apply potentials to the first, second, and third electrodes, respectively. Another voltage source V4 is connected to the sample to apply a fourth potential, which can be grounded. The potential can be defined relative to the sample 208. The first, second, and third electrodes each have an aperture through which the individual sub-beams propagate. The second potential can be similar to the potential of the sample, for example, in the range of +50 V to +200 V relative to the sample. Alternatively, the second potential can be in the range of about +500 V to about +1,500 V relative to the sample. If the detector module 402 is above the lowest electrode in the optical column, the higher potential is useful. The first and / or second potentials can be varied according to the aperture or group of apertures to achieve focus correction.

[0055] Ideally, in one embodiment, the third electrode is omitted. An objective with only two electrodes can have lower aberrations than an objective with more electrodes. A three-electrode objective can have a larger potential difference between the electrodes and thus achieve a stronger lens. Additional electrodes (i.e., more than two electrodes) provide additional degrees of freedom for controlling the electron trajectory, such as for focusing secondary electrons and the incident beam.

[0056] As mentioned above, a control lens is needed to determine the landing energy. However, it is possible to use an additional objective lens 300 to control the landing energy. In this case, the potential difference throughout the objective lens changes when different landing energies are selected. One example of a situation where the landing energy needs to be partially changed by altering the potential difference throughout the objective lens is to prevent the focal point of the sub-beam from becoming too close to the objective lens. This can occur, for example, when the landing energy is reduced. This is because the focal length of the objective lens is roughly proportional to the selected landing energy. By reducing the potential difference throughout the objective lens, and thereby reducing the electric field inside the objective lens, the focal length of the objective lens increases again, resulting in the focal position being further below the objective lens.

[0057] In the depicted configuration, the control lens 600 includes three electrodes 601 to 603 connected to potential sources V5 to V7. Electrodes 601 to 603 may be spaced a few millimeters (e.g., 3 mm). The distance between the control lens and the objective lens (i.e., the gap between the lower electrode 602 and the upper electrode of the objective lens) can be selected from a wide range, such as 2 mm to 200 mm or greater. Smaller resolution makes alignment easier, while larger resolution allows the use of weaker lenses, thereby reducing aberrations. Ideally, the potential V5 of the uppermost electrode 603 of the control lens 600 is maintained at the same potential as the next electro-optical element (e.g., deflector 235) in the counter-current direction of the control lens. The potential V7 applied to the lower electrode 602 can be varied to determine the beam energy. The potential V6 applied to the intermediate electrode 601 can be varied to determine the lens strength of the control lens 600 and thus control the beam angle and reduction rate. Ideally, the lower electrode 602 of the control lens, the uppermost electrode of the objective lens, and the sample have substantially the same potential. In one design, the upper electrode of the objective lens 300 is omitted. In this case, ideally, the lower electrode 602 of the control lens and the electrode 301 of the objective lens have substantially the same potential. It should be noted that even if the landing energy does not need to be changed or is changed by other means, the control lens can be used to control the beam angle. The focusing position of the sub-beam is determined by the combination of the actions of the individual control lenses and individual objectives.

[0058] In one example, to obtain landing energy in the range of 1.5 kV to 2.5 kV, potentials V1, V2, V4, V5, V6, and V7 can be set as indicated in Table 1 below. The potentials in this table are given as beam energy values ​​in keV, which are equivalent to the electrode potentials relative to the cathode of beam source 201. It should be understood that in designing an electro-optical system, there is considerable design freedom regarding which point in the system is set to ground potential, and the operation of the system is determined by potential difference rather than absolute potential. Table 1 Landing energy 1.5 keV 2.5 keV 3.5 keV V1 29 keV 30 keV 31 keV V2 1.55 keV 2.55 keV 3.55 keV V3 (or omitted) 29 keV 30 keV 31 keV V4 1.5 keV 2.5 keV 3.5 keV V5 30 keV 30 keV 30 keV V6 19.3 keV 20.1 keV 20.9 keV V7 29 keV 30 keV 31 keV

[0059] As will be seen, the beam energies at V1, V3, and V7 are the same. In the embodiment, the beam energies at these points can be between 10 keV and 50 keV. If a lower potential is chosen, the electrode spacing can be reduced, especially in the objective lens, to limit the reduction of the electric field.

[0060] When a control lens, rather than a condenser lens, is used for electron beam angular / reduction correction, the collimator remains at the intermediate focal plane, eliminating the need for collimator astigmatism correction. Furthermore, the landing energy can vary across a wide range while maintaining optimal field intensity in the objective. This minimizes objective aberrations. The intensity of the condenser lens (if used) also remains constant, thus avoiding any additional aberrations introduced due to the collimator not being at the intermediate focal plane or changes in the electron path through the condenser lens.

[0061] In some embodiments, the charged particle assessment tool further includes one or more aberration correctors that reduce one or more aberrations in the sub-beams. In one embodiment, each of at least a subset of the aberration correctors is located in or directly adjacent to one of the intermediate focal points (e.g., in or near the intermediate image plane). The sub-beams have a minimum cross-sectional area in or near a focal plane such as the intermediate plane. This provides more space for the aberration correctors compared to the space available elsewhere (i.e., in the direction of the intermediate plane upstream or downstream) (or compared to the space available in an alternative configuration without an intermediate image plane).

[0062] In one embodiment, an aberration corrector located at or directly adjacent to the intermediate focal point (or intermediate image plane) includes a deflector to correct for sources 201 that appear at different locations for different beams. The corrector can be used to correct macroscopic aberrations caused by the sources that prevent proper alignment between each sub-beam and its corresponding objective.

[0063] Aberration correctors can correct aberrations that prevent proper alignment. Such aberrations can also cause misalignment between the sub-beams and the corrector. For this reason, alternatively, it may be necessary to position the aberration corrector at or near the condenser lens of the condenser lens array 231 (e.g., where each such aberration corrector is integrated with or directly adjacent to one or more of the condenser lenses 231). This is desirable because at or near the condenser lens of the condenser lens array 231, aberrations will not yet have caused displacement of the corresponding sub-beams, as the condenser lens and the beam aperture are vertically close to or coincident. However, the challenge of positioning the corrector at or near the condenser lens is that the sub-beams at this location each have a relatively large cross-sectional area and a relatively small pitch, respectively, compared to locations further downstream. The aberration corrector may be an individual programmable deflector based on CMOS as disclosed in EP2702595A1 or a multi-stage deflector array as disclosed in EP2715768A2, the descriptions of the fine beam manipulators in the two documents EP2702595A1 and EP2715768A2 are hereby incorporated by reference.

[0064] In some embodiments, each of at least a subset of aberration correctors is integrated with or directly adjacent to one or more of the objectives 234. In one embodiment, these aberration correctors reduce one or more of: field curvature; focusing error; and astigmatism. Alternatively or additionally, one or more scanning deflectors (not shown) may be integrated with or directly adjacent to one or more of the objectives 234, thereby enabling sub-beams 211, 212, 214 to scan across the sample 208. In one embodiment, the scanning deflectors described in US 2010 / 0276606, the entire text of which is hereby incorporated by reference, may be used.

[0065] In some embodiments, the objective array assembly includes a detector having a detector module 402 aligned with at least one electrode of the objective array 241. The detector module 402 may be in the form of a detector array. In one embodiment, at least a portion of the detector is adjacent to and / or integrated with the objective array 241. For example, the detector module 402 may be implemented by integrating a CMOS wafer detector into the bottom electrode of the objective array 241. Integration of the detector module 402 into the objective array replaces secondary pillars. The CMOS wafer is preferably oriented to face the sample (due to the small distance (e.g., 100 μm) between the wafer and the bottom of the electro-optical system). In one embodiment, electrodes for capturing secondary electronic signals are formed in the top metal layer of the CMOS device. These electrodes may be formed in other layers. Power and control signals of the CMOS may be connected to the CMOS via silicon vias. For stability, the bottom electrode preferably consists of two components: a CMOS chip and a passive Si plate with holes. This plate shields the CMOS from the effects of high electronic fields.

[0066] To maximize detection efficiency, the electrode surface needs to be as large as possible, such that virtually all of the objective array's area (except for the aperture) is occupied by electrodes, and each electrode has a diameter substantially equal to the array pitch. In one embodiment, the electrodes are circular in shape, but this shape can be made square to maximize the detection area. The diameter of the substrate perforations can also be minimized. The typical size of the electron beam is approximately 5 to 15 micrometers.

[0067] In one embodiment, a single electrode surrounds each aperture. In another embodiment, a plurality of electrode elements are provided around each aperture. Electrons captured by the electrode elements surrounding an aperture can be combined into a single signal or used to generate independent signals. The electrode elements can be radially divided (i.e., to form a plurality of concentric rings), angularly divided (i.e., to form a plurality of segmented blocks), radially and angularly divided, or divided in any other suitable manner.

[0068] However, a larger electrode surface area results in a larger parasitic capacitance, thus leading to a lower bandwidth. For this reason, it may be necessary to limit the outer diameter of the electrode, especially when a larger electrode only provides a slightly higher detection efficiency but a significantly larger capacitance. Circular (ring-shaped) electrodes offer a good trade-off between collection efficiency and parasitic capacitance.

[0069] A larger electrode outer diameter can also lead to greater crosstalk (sensitivity to signals from adjacent holes). This is also a reason to make the electrode outer diameter smaller, especially when a larger electrode only provides slightly greater detection efficiency but significantly greater crosstalk.

[0070] The backscattered and / or secondary electron currents collected by the electrodes are amplified by a transimpedance amplifier.

[0071] An exemplary embodiment of a detector integrated into an objective lens array is shown in [picture] [6] The figure schematically illustrates a portion of the multibeam objective 401 in cross-section. In this embodiment, the detector includes a detector module 402 comprising a plurality of detector elements 405 (e.g., sensing elements such as capture electrodes) (e.g., an array of detector elements 405), which preferably serve as an array of detector elements (i.e., a plurality of detector elements preferably patterned or arranged above a two-dimensional surface). In this embodiment, the detector module 402 is provided on the output side of the objective array. The output side is the output side of the objective 401. [picture] [7] is a bottom view of a detector module 402, which includes a substrate 404 on which a plurality of capturing electrodes 405, each surrounding a beam aperture 406, are provided. The beam aperture 406 may be formed by etching through the substrate 404. [picture] In the configuration shown in [7], the beam aperture 406 is displayed in a rectangular array. The beam aperture 406 can also be configured in different ways, for example, as shown in... [picture] [8] describes the configuration of a hexagonal enclosed package array.

[0072] [picture] [9] A portion of the detector module 402 is depicted in cross-section at a larger scale. The capture electrode 405 forms the bottommost (i.e., closest to the sample) surface of the detector module 402. A logic layer 407 is provided between the capture electrode 405 and the body of the silicon substrate 404. The logic layer 407 may include amplifiers (e.g., transimpedance amplifiers), analog-to-digital converters, and readout logic. In one embodiment, each capture electrode 405 contains one amplifier and one analog-to-digital converter. Circuitry characterized by these elements may be contained within unit regions referred to as aperture-associated cells. The detector module 402 may have several aperture-associated cells; preferably, these cells have similar shapes. The logic layer 407 and the capture electrode 405 may be fabricated using CMOS processes, wherein the capture electrode 405 forms the final metallization layer.

[0073] Wiring layer 408 is provided on the back side of substrate 404 or within substrate 404 and is connected to logic layer 407 via through-silicon vias 409. The number of through-silicon vias 409 need not be the same as the number of beam apertures 406. Specifically, if the electrode signals are digitized in logic layer 407, only a few through-silicon vias are needed to provide the data bus. Wiring layer 408 may include control lines, data lines, and power lines. It should be noted that despite the presence of beam apertures 406, there is still sufficient space for all necessary connections. Bipolar or other manufacturing techniques may also be used to fabricate detector module 402. Printed circuit boards and / or other semiconductor wafers may be provided on the back side of detector module 402.

[0074] The integrated detector module 402 described above is particularly advantageous when used with instruments having tunable landing energies, as it allows for optimization of secondary electron capture for the landing energy range. The detector module, in array form, can also be integrated into other electrode arrays, not just the lowest electrode array. Further details and alternative configurations of detector modules integrated into objectives can be found in EP application No. 20184160.8, which is hereby incorporated by reference. [ ]

[0075] [picture]

[10] A schematic diagram of another exemplary electro-optical column for evaluating a system. The column includes an objective array assembly. The objective array assembly includes an objective array 241. The objective array 241 includes a plurality of objectives. Each objective includes at least two electrodes (e.g., two or three electrodes) connected to a respective potential source. The objective array 241 may include two or more (e.g., three) plate electrode arrays connected to a respective potential source. The plate electrode arrays of the objective array 241 may be referred to as objective electrodes. Each objective formed by the plate electrode array may be a microlens that operates on different sub-beams or sub-beam groups in a multi-beam system. Each plate defines a plurality of apertures (which may also be referred to as holes). The position of each aperture in a plate corresponds to the position of a corresponding aperture (or corresponding hole) in another plate (or plates). The corresponding apertures define the objective, and each set of corresponding holes thus operates on the same sub-beam or sub-beam group in the multi-beam system during use. Each objective projects individual sub-beams of the multi-beam array onto sample 208. See also the description of objective array 234.

[0076] In some configurations, the apertures in the objective array 241 are adapted to compensate for off-axis aberrations in multi-beam arrays. For example, the apertures of one or more of the objective electrodes can be shaped, sized, and / or positioned to compensate for off-axis aberrations. For example, these apertures can have different ranges of area for compensating for field curvature, different ranges of ellipticity for compensating for astigmatism, and / or different ranges of displacement of the self-nominal grid position for compensating for distortions caused by telecentricity errors. See, for example, EPA 21166214.3, filed March 31, 2021, which is incorporated herein by reference for the purpose of off-axis aberration correction.

[0077] The objective lens array assembly further includes 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 respective potential source. The control lens array 250 may include two or more (e.g., three) plate electrode arrays connected to the respective potential sources. The plate electrode arrays of the control lens array 250 may be referred to as control electrodes. The control lens array 250 is associated with the objective lens array 241 (e.g., the two arrays are positioned close to each other and / or mechanically connected to each other and / or controlled together as a unit). The control lens array 250 is positioned in the countercurrent direction to the objective lens array 241. The control lenses prefocus the sub-beams (e.g., apply focusing action to the sub-beams before they reach the objective lens array 241). Prefocusing can reduce sub-beam divergence or increase sub-beam convergence rate. The control lens array and the objective lens array operate together to provide a combined focal length. Combined operation without an intermediate focus reduces aberration risks.

[0078] In one embodiment, the electro-optical system including the objective lens array assembly is configured to control the objective lens assembly (e.g., by controlling the potential applied to the electrodes of the control lens array 250) such that the focal length of the control lens is greater than the separation between the control lens array 250 and the objective lens array 241. The control lens array 250 and the objective lens array 241 can thus be positioned relatively close together, wherein the focusing action from the control lens array 250 is too weak to form an intermediate focal point between the control lens array 250 and the objective lens array 241. In other embodiments, the objective lens array assembly can be configured to form an intermediate focal point between the control lens array 250 and the objective lens array 241.

[0079] In one embodiment, the control lens array is an interchangeable module, which can be used alone or in combination with other components such as objective lens arrays and / or detector modules. This interchangeable module can be field-replaceable, meaning it can be replaced by a field engineer with a new module. Field-replaceable means that the module can be removed and replaced with the same or a different module while maintaining the vacuum at the location of the electro-optical tool 40. Only the sections corresponding to the columns of the module are vented for removal, return, or replacement of the module.

[0080] The control lens array can be in the same module as the objective lens array 241, that is, forming an objective lens array assembly or objective lens configuration, or it can be in a separate module.

[0081] A power source can be provided to apply individual potentials to the electrodes of the control lenses of the control lens array 250 and the objective lenses of the objective lens array 241.

[0082] In addition to the objective lens array 241, a control lens array 250 provides additional degrees of freedom for controlling the properties of the sub-beams. This additional degree of freedom is provided even when the control lens array 250 and the objective lens array 241 are provided relatively close together, for example, to prevent an intermediate focus from forming between the control lens array 250 and the objective lens array 241. The control lens array 250 can be used to optimize the beam angle with respect to the beam reduction rate and / or control the beam energy delivered to the objective lens array 241. The control lens may contain two, three, or more than three electrodes. If two electrodes are present, the reduction rate and landing energy are jointly controlled. If three or more electrodes are present, the reduction rate and landing energy can be controlled independently. The control lens can therefore be configured to adjust the reduction rate and / or beam angle of each individual sub-beam (e.g., by applying suitable individual potentials to the electrodes of the control lens and objective lens using a power supply). This optimization can be achieved without excessively negatively impacting the number of objectives and without excessively degrading the aberrations of the objectives (e.g., without increasing the intensity of the objectives).

[0083] exist [picture]

[10] In an embodiment, the electro-optical system includes a source 201. The source 201 provides a beam of charged particles (e.g., electrons). A multi-beam output is provided by the source 201 and focused onto the sample 208. Sub-beams can be output from the beam, for example using a beam limiter that defines a beam-limiting aperture array. The source 201 is ideally a high-brightness thermal field emitter with a good trade-off between brightness and total emission current. In the example shown, a collimator is provided in the countercurrent direction of the objective array assembly. The collimator may include a giant collimator 270. The giant collimator 270 acts on the beam before it has split into multiple beams from the source 201. The giant collimator 270 bends individual portions of the beam by a certain amount to effectively ensure that the beam axis of each of the sub-beams output from the beam is substantially perpendicular to the sample 208 (i.e., substantially 90° to the nominal surface of the sample 208). The giant collimator 270 applies macroscopic collimation to the beam. The giant collimator 270 can therefore act on the entire beam, rather than comprising an array of collimator elements each configured to act on different individual portions of the beam. The giant collimator 270 may include magnetic lenses or magnetic lens configurations comprising a plurality of magnetic lens sub-units (e.g., a plurality of electromagnets forming a multipole configuration). Alternatively or additionally, the giant collimator may be implemented at least partially electrostatically. The giant collimator may include electrostatic lenses or electrostatic lens configurations comprising a plurality of electrostatic lens sub-units. The giant collimator 270 may use a combination of magnetic lenses and electrostatic lenses.

[0084] exist [picture]

[10] In one embodiment, a giant scan deflector 265 is provided to scan the sample 208 by means of a sub-beam. The giant scan deflector 265 deflects individual portions of the beam to scan the sample 208 by means of a sub-beam. In one embodiment, the giant scan deflector 265 includes, for example, a macroscopic multipole deflector having eight or more poles. The deflection is to cause the sub-beams derived from the beam to scan across the sample 208 in one direction (e.g., parallel to a single axis, such as the X-axis) or in two directions (e.g., relative to two non-parallel axes, such as the X-axis and the Y-axis). In some configurations, the scanning of the sub-beams is coordinated with the movement of the sample 208. For example, the combination of scanning the sample 208 parallel to the X-axis while moving it parallel to the Y-axis can be repeated at different movement positions on the sample to process multiple parallel stripes on the sample 208. Larger movements of the sample 208 can then be used to jump to new processing positions on the sample 208. An example of this movement is described in EPA filing 21171877.0, filed May 3, 2021, which is specifically incorporated for the control of beam scanning as the stage moves. The giant scanning deflector 265 acts macroscopically on all beams, rather than comprising an array of deflector elements each configured to act on different individual portions of the beams. In the illustrated embodiment, the giant scanning deflector 265 is provided between the giant collimator 270 and the control lens array 250.

[0085] Any of the objective array assemblies described herein may further include a detector (e.g., detector module 402). The detector detects charged particles emitted from sample 208. The detected charged particles may include any of the charged particles detected by SEM, including secondary and / or backscattered electrons emitted from sample 208. An exemplary configuration of detector module 402 is referenced above. [picture] [6] [To the image] [9] Describe it.

[0086] exist [picture] In a variation of the embodiment of

[10] , the objective array assembly may include a scanning deflector array. The scanning deflector array includes a plurality of scanning deflectors. Each scanning deflector causes a particular sub-beam to scan across the sample 208. The scanning deflector array may therefore include a scanning deflector for each sub-beam. Deflection is performed to cause the sub-beam to scan across the sample 208 in one or two directions (i.e., one-dimensionally or two-dimensionally). In one embodiment, the scanning deflector described in EP2425444, which is specifically incorporated herein by reference in its entirety, may be used to implement the scanning deflector array. The scanning deflector array is positioned between the objective array 241 and the control lens array 250. A scanning deflector array may be provided instead of a giant scanning deflector 265. In other embodiments, both the giant scanning deflector 265 and the scanning deflector array are provided and can be operated synchronously. In some embodiments, such as [picture] As illustrated in

[10] , the control lens array 250 is a first deflection or lensing electro-optic array element in the beam path in the downstream direction of the source 201.

[0087] An array of collimator elements can be provided to replace the giant collimator 270. Although not shown, this variation could also be applied. [picture] [3] An embodiment is provided to provide an embodiment with a giant scanning deflector and collimator element array. Each collimator element collimates a separate sub-beam. The collimator element array can be spatially more compact than the giant collimator 270. Providing the collimator element array and scanning deflector array 260 together can thus provide space savings. This space saving is desirable because it includes multiple electro-optical systems of the objective lens array assembly provided in an electro-optical system array. In this embodiment, a giant condenser lens or condenser lens array may not be present. In this case, the control lens thus provides the possibility of optimizing the beam angle and reduction rate for changes in landing energy.

[0088] In one embodiment, an array of electro-optical systems is provided. This array may include any of the plurality of electro-optical systems described herein. Each of the electro-optical systems simultaneously focuses individual multiple beams onto different regions of the same sample. Each electro-optical system may form a sub-beam from charged particle beams from different individual sources 201. Each individual source 201 may be one of a plurality of sources 201. At least a subset of the plurality of sources 201 may be provided as a source array. The source array may include a plurality of sources 201 provided on a common substrate. Simultaneous focusing of multiple multiple beams onto different regions of the same sample allows for simultaneous processing (e.g., evaluation) of an enlarged region of sample 208. The electro-optical systems in the array may be arranged adjacent to each other to project individual multiple beams onto adjacent regions of sample 208. Any number of electro-optical systems may be used in this array. Preferably, the number of electro-optical systems is in the range of 9 to 200. In one embodiment, the electro-optical systems are arranged in a rectangular array or a hexagonal array. In other embodiments, the electro-optical systems are provided in an irregular array or in a regular array having a geometry other than rectangular or hexagonal. When referring to a single electro-optical system, each electro-optical system in the array can be configured in any of the ways described herein. As mentioned above, the scan deflector array 260 and the collimator element array 271 are particularly suitable for inclusion in the electro-optical system array due to their spatial compactness, which facilitates the close positioning of the electro-optical systems to each other.

[0089] [picture]

[11] A portion of another example of an objective lens array assembly is depicted. This objective lens array assembly includes a control lens array 250 and an objective lens array 241. This objective lens array assembly can be used in… [picture]

[10] In the configuration. The control lens array 250 may include at least three electrodes. The objective lens array 241 may include at least two electrodes. In this example, the objective lens array assembly further includes 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 beam shaping limiting aperture array or a final beam limiting aperture array. The beam shaping limiter 242 may include a plate (which may be a plate-like body) having a plurality of apertures. The beam shaping limiter 242 is in the flow direction of at least one electrode (in case all electrodes) of the control lens array 250. In some embodiments, the beam shaping limiter 242 is in the flow direction of at least one electrode (in case all electrodes) of the objective lens array 241. In another embodiment, it may be an array, such as the bottom array of the objective lens array 241.

[0090] In one configuration, the beam shaping limiter 242 is structurally integrated with the electrodes of the objective array 241. Each beam limiting aperture has a beam limiting effect, thereby allowing only a selected portion of the sub-beam incident on the beam shaping limiter 242 to pass through the beam limiting aperture 124. This selected portion allows only a portion of each sub-beam that passes through the central portion of each aperture in the objective array to reach the sample 208.

[0091] In some embodiments, the electro-optical system further includes an upper beam limiter 252. The upper beam limiter 252 defines a beam-limiting aperture array or, for example, a beam array generated from a source beam from source 201. The upper beam limiter 252 may include a plate (which may be a plate-like body) having a plurality of apertures. The upper beam limiter 252 forms sub-beams from the charged particle beam emitted from source 201. The upper beam limiter 252 may block (e.g., absorb) portions of the beam other than those contributing to the formation of sub-beams to prevent interference with the downstream sub-beams.

[0092] The upper beam limiter 252 may form part of the objective lens array assembly. The upper beam limiter 252 may be, for example, adjacent to and / or integrated with the control lens array 250 (e.g., adjacent to and / or integrated with the electrode closest to source 201 of the control lens array 250). In one embodiment, the upper beam limiter 252 defines a beam limiting aperture larger (e.g., having a larger cross-sectional area) than the beam limiting aperture of the beam shaping limiter 242. The beam limiting aperture of the beam shaping limiter 242 may therefore have a smaller size than the corresponding aperture defined in the objective lens array 241 and / or the control lens array 250.

[0093] The beam shaping limiter 242 is ideally configured to have a beam-limiting effect (i.e., to remove a portion of each sub-beam incident on the beam shaping limiter 242). The beam shaping limiter 242 can, for example, be configured to ensure that each sub-beam exiting the objective array 241 has passed through the center of the respective objective. Additionally, the beam shaping limiter 242 reduces the length of the scan for the sub-beams. The distance is reduced to the length of the beam path from the beam shaping limiter 242 to the sample surface.

[0094] The beam shaping limiter 242 can be integrally formed with the bottom electrode of the objective array 241. Typically, the beam shaping limiter 242 needs to be positioned adjacent to the electrode with the strongest lensing effect for each objective. In one configuration, the beam shaping limiter 242 needs to be provided in the countercurrent direction of the detector module 402 of the detector. Providing the beam shaping limiter 242 in the countercurrent direction of the detector module 402 ensures that the beam shaping limiter 242 will not obstruct charged particles emitted from the sample 208 and prevent such charged particles from reaching the detector module 402. Therefore, the beam shaping limiter 242 can be provided directly adjacent to the detector module 402 in the countercurrent direction.

[0095] As mentioned above, refer to specific sources. [picture] [3] [To the image] As described in [5], the control lens array 250 can be used to vary the landing energy of the sub-beams on the sample 208 within a desired range while maintaining an optimal field within the objective array 241. Maintaining an optimal field within the objective minimizes aberrations and improves (minimizes) resolution. That is, the improved resolution here is a reduction in the minimum resolvable size (size) of the sub-beams at the sample. The control lens array 250 can also be used to optimize the beam angle and reduction ratio. The result of maintaining an optimal field within the objective array 241 while varying the landing energy is a change in the position of the image plane. The change in the position of the image plane means that the sample 208 must be displaced to maintain proper focusing of the sub-beams on the sample 208. The displacement of the sample 208 requires that the detector module 402, which is used to detect signal electrons emitted from the sample 208, also be displaced, for example, to maintain a constant distance between the sample 208 and the detector module 402. These requirements can increase additional mechanical and / or operational complexity.

[0096] The following describes a configuration that allows control of landing energy without displacement of sample 208 or detector module 402 and without replacement of the objective array assembly. A configuration that provides additional degrees of freedom for controlling the properties of the sub-beams illuminating sample 208 is also described.

[0097] An evaluation system is provided to guide charged particles in a sub-beam toward sample 208. This evaluation system detects signal electrons emitted from sample 208 (e.g., using detector module 402) to obtain information about sample 208. The sub-beams are configured in a multi-beam configuration (which may also be referred to as a multi-beam array). The system includes a control lens array 250. The control lens array 250 can take reference... [picture] [3] [,picture] [5] and [picture]

[10] (described above) and [picture]

[0011] Any of the forms described above and, more particularly, below. The system includes an objective array 241. The objective array 241 may take the form of a reference. [picture] [3] [,picture] [5] [To the image]

[0010] (described above) and [picture]

[11] (as described below) any of the forms described.

[0098] [picture]

[11] is a schematic side cross-sectional view of a portion of the illustrative control lens array 250 and objective lens array 241. [picture] As depicted in

[11] , the control lens array 250 may be defined by a plurality of control electrodes 501 to 503. Each control electrode 501 to 503 may include a plate-like element having an aperture for each sub-beam path 510 (forming an aperture array). The objective lens array 241 may be defined by a plurality of objective lenses 503 to 504. Each objective lens electrode 503 to 504 may include a plate-like element having an aperture for each sub-beam path 510 (forming an aperture array). The control electrodes 501 to 503 and the objective lenses 503 to 504 may be referred to as lens electrodes. The combination of the control lens array 250 and the objective lens array 241 may include at least four such lens electrodes. These lens electrodes may be orthogonal to the sub-beam paths 510 of the multi-beam array and / or arranged in series along the sub-beam paths 510 of the multi-beam array.

[0099] [picture]

[11] illustrates five exemplary sub-beam paths 510. Control electrodes 501 to 503 are arranged in series along the sub-beam paths 510 and define individual apertures aligned with the sub-beam paths 510 to define control lenses. Each control lens is thus aligned with the sub-beam path 510 of the respective sub-beam and operates the sub-beam (e.g., electrostatically). Each control electrode 501 to 503 may operate on a portion or all of the sub-beams. Each objective in the objective array 241 may be aligned with the sub-beam path 510, which is aligned with the respective control lens. The objective array 241 directs the sub-beams onto the sample 208.

[0100] This configuration can be described as having four or more lens electrodes as plates. Defined apertures, such as an aperture array, are formed within these plates and aligned with multiple beams in a corresponding beam array. The electrodes can be divided into two or more groups, for example, to provide a control electrode group and an objective electrode group. In one configuration, the objective electrode group has at least three electrodes and the control electrode group has at least two electrodes.

[0101] exist [picture] In the example of

[11] , the objective electrode 503 furthest from the sample 208 (which may be referred to as the most countercurrent direction electrode of the objective lens array 241) and the control electrode 503 closest to the sample 208 (which may be referred to as the most downstream direction electrode of the control lens array 250) are provided by a common electrode. Therefore, the most countercurrent direction electrode of the objective electrode group is a common electrode and also a component of the control electrode group. The surface of the common electrode 503 facing away from the sample 208 (which may be described as a countercurrent direction surface) contributes functionality to the control lens array and can therefore be considered to contain a portion of the control lens array. The surface of the common electrode 503 facing the sample 208 (which may be referred to as a downstream direction surface) contributes functionality to the objective lens array 241 and can therefore be considered to contain a portion of the objective lens array 241.

[0102] Providing a common electrode is advantageous when it is necessary to position the control lens array 250 close to the objective lens array 241. This is more likely in configurations that do not use the scan deflector 260, but instead use a giant scan deflector 265. This is because when using the scan deflector 260 array, it is necessary to position the scan deflector 260 array between the control lens array 250 and the objective lens array 241, for example, to make the distance between the scan deflector 260 and the objective lens array 241 as short as possible. A configuration with a giant scan deflector 265 in... [picture] An example is given in

[10] . However, it should be noted that the image still does not have a condenser lens array but has a scanning deflector array. [picture]

[10] Variations in the configuration are possible. In such configurations, it may also be necessary to position the scanning deflector array between the control lens array and the objective lens array. Alternatively, the scanning deflector array may be positioned elsewhere, such as within the control lens array or in the reverse direction of the control lens array, such as between the control lens array and the beam limiting aperture array.

[0103] An evaluation system comprising a control lens array 250 and an objective lens array 241 is configured to perform various functions as described below. These functions can be performed by controlling the control lens array 250 and the objective lens array 241. The evaluation system may therefore include a controller 500 (e.g., [picture] [3] and [picture]

[10] (illustrated schematically). As described below, the controller 500 can be implemented in a computer by any suitable combination of components (such as CPU, RAM, etc.) used to provide the required functionality. See above reference [picture] As described in [5], the control electrode and the objective lens electrode can be controlled by connecting these electrodes to a potential source. The controller 500 may therefore include and / or control a potential source that applies a potential to the different lens electrodes.

[0104] Any reference in this document to an evaluation system (or, in short, a system) configured to perform functionality is intended to cover the state in which the controller 500 is configured to perform functionality (e.g., by being appropriately programmed to provide necessary control signals to devices such as potential sources).

[0105] In some configurations, the system (e.g., via controller 500) is configured to implement a plurality of selectable landing energies for sub-beams of a multi-beam system (or, where appropriate, all sub-beams). These selectable landing energies are implemented by applying corresponding potentials to control electrodes 501-503 and objective lens electrodes 503-504 (e.g., via individual potential sources). Different potentials can be applied for each selectable landing energy. The system thus allows the selection of different landing energies for the sub-beams at different corresponding times. Selectable landing energies may comprise one or more consecutive ranges of landing energies. In this case, the system will be able to select any landing energy within one or more consecutive ranges. Alternatively or additionally, selectable landing energies may comprise a plurality of predetermined discrete landing energies. This selection can be performed by a user. The system can therefore receive user input (e.g., via a user interface of a computer system or as an input data stream) and select selectable landing energies at least partially (i.e., entirely or partially) based on the received user input. Alternatively or additionally, the system may operate at least partially (i.e., fully or partially) automatically. The system may select the landing energy, for example, at least partially based on predefined programs or in response to one or more input parameters determined, for example, by an application or model. For instance, the input parameters may represent measurements performed by the system.

[0106] The choice of landing energy can be determined by the specific inspection context. For example, the landing energy can be selected to optimize secondary electron yield and contrast (which can be defined as the yield difference between the feature and the background). The landing energy required to achieve this will depend on the material being inspected. The nature of the defect of interest can also play a role. In the case of focusing on physical defects, material properties will determine the secondary electron yield. In the case of focusing on voltage contrast defects, charging behavior and therefore secondary electron yield will depend on whether the circuit can draw charge. Alternatively or additionally, the landing energy can be selected to control charging (which affects distortion and secondary electron yield). Alternatively or additionally, the landing energy can be selected to achieve the desired electro-optical performance. For example, a trade-off can be made between the resolution degradation resulting from selecting a lower landing energy and the improvement in secondary electron yield.

[0107] The system is configured (e.g., via controller 500) to select the corresponding potentials for different landing energies such that the spatial relationship between the system's image plane and all control electrodes 501 to 503 and objective lens electrodes 503 to 504 is the same for each of the selectable landing energies. Therefore, the separation between all electrodes and the system's image plane, and between each electrode and the system's image plane, remains the same regardless of which selectable landing energy is applied. Users can thus select different landing energies without adjusting the positions of any of the electrodes 501 to 504, sample 208, or detector module 402.

[0108] In some configurations, the system is configured (e.g., via controller 500) to apply the same potential to control electrode 501, which is furthest from sample 208 (and is the portion of the control lens aligned with the sub-beam path of the selected sub-beam for the landing energy), for at least a portion of the selectable landing energy. The potential applied to control electrode 501 can be determined, for example, by the beam energy delivered by the source module. The source module provides a beam of charged particles from which sub-beams are derived. Control electrode 501 can be fixed, for example, to a potential corresponding to beam energy between 10 keV and 50 keV.

[0109] In some configurations, the system is configured (e.g., via controller 500) to apply different potentials to the objective electrode 503 furthest from sample 208 (and the portion of the objective aligned with the sub-beam path of the sub-beam to which the selected landing energy is targeted) for each of at least a portion of the selectable landing energies. For example, each potential can be selected to provide the same distance between the objective electrode 503 and the system's image plane. The potential applied to the objective electrode 503 determines the field strength of the electric field in the objective array 241, and thus the focal length of each objective. Therefore, it is possible to control the position of the image plane by controlling the potential applied to the objective electrode 503.

[0110] In some configurations, the system is configured (e.g., via controller 500) to control the landing energy (i.e., to select the desired landing energy from a range of selectable landing energies) by controlling at least the potential applied to the objective electrode 504 closest to the sample (and the portion of the objective aligned with the sub-beam path of the selected sub-beam for the landing energy). For example, the objective electrode 504 can be set to a potential corresponding to a beam energy equal to the desired landing energy plus a predetermined offset. The predetermined offset can be, for example, in the range of -50 eV to 300 eV. This offset sets the electric field strength at the sample surface. The electric field strength plays a role in determining secondary electron contrast, particularly in voltage contrast applications. In the case of detecting secondary electrons, the offset voltage can typically be about 50 V or higher to ensure adequate detection efficiency, but a lower offset voltage may be sufficient if the distance between the detector and the sample is small enough. If it is desirable to repel secondary electrons, for example, if we are interested in the backscattered signal, a negative voltage is used.

[0111] In some configurations, the system is configured (e.g., via controller 500) to control the control lens array 250 to minimize resolution for each of a plurality of selectable landing energies. This can be achieved, at least in part, by adjusting the control lens array 250 at each selectable landing energy to keep the reduction ratio (from the electron source to the sample) divided by the angular reduction ratio of the system the same for each of the selectable landing energies. This can be achieved, for example, by controlling the potential applied to the intermediate (preferably intermediate) control electrode 502 of the control lens array 250 (e.g., where the control lens array 250 is defined by three control electrodes 501 to 503; note that the intermediate electrode may simply be the intermediate control electrode of a lens array having an odd number of electrodes). Controlling the potential applied to the intermediate (preferably intermediate) control electrode 502 controls the reduction ratio. Keeping the reduction ratio divided by the angular reduction ratio the same for different landing energies ensures that off-axis aberration remains constant. The hard-coded correction for off-axis aberration remains effective, thereby keeping the net aberration (after correction) low for different landing energies. This is achieved without having to replace the individual objective electrodes or objective array 241, which could unnecessarily introduce downtime and / or inconvenience.

[0112] [picture]

[12] To demonstrate an electro-optical column using a non-condenser lens array (e.g., characterized by a giant condenser lens). [picture]

[10] Depicts the system, showing a graph of the predicted change in beam current of the sub-beam at sample 208 relative to the sub-beam resolution. Resolution (i.e., the smallest resolvable size of the sub-beam at the sample as described above) has distance units, such as nanometers. This note is for reference to other graphs (e.g., [picture]

[13] [,picture]

[14] [and illustrations]

[16] ) Other representations related to the resolution referenced (or the minimum resolvable size of the beam on the sample). Curve, that is, in [picture] The curves in

[12] were obtained by simulating an electrostatic field and tracing electrons through the field ray. Curve 521 corresponds to a landing energy of 2.5 keV. Curve 522 corresponds to a landing energy of 1 keV. For each curve, each discontinuity point on the curve represents a discontinuous physical configuration of the electro-optic column optimized for different combinations of beam current and resolution (including, for example, off-axis compensation via hard-coded data). Generally, a high total current is required to achieve good yield, and a minimum resolution is required to provide measurements with good spatial resolution. The curves show the need to balance between the two quantities: increasing the beam current increases the resolution, and vice versa. Furthermore, the curves for beam current versus resolution are different for different landing energies.

[0113] [picture]

[13] A graph is provided to illustrate eight example curves (solid line curves 523 with hollow squares) showing the selection of different landing energies in eight different physical configurations of the column. For each configuration represented by one of the individual curves in curve 523, a plurality of different landing energies are selected in steps of 250 eV between a landing energy of 2.5 keV corresponding to curve 521 and a landing energy of 1 keV corresponding to curve 522. At each selected landing energy, the system controls the control lens array 250 to minimize resolution by changing the reduction rate of the control lens array 250. For example, this can be achieved by keeping the system's reduction rate constant by dividing it by the system's angular reduction rate to ensure that hard-coded off-axis aberration compensation remains effective and / or by changing the reduction rate of the control lens array to compensate for other effects, such as changes in field curvature caused by distortion of elements (e.g., electrodes) due to the electric field. In each case, the potentials applied to the control electrodes and objective lenses are selected to maintain the same spatial relationship between the image plane and all control electrodes and objective lenses. Each curve 523 thus shows the range of available landing energies and corresponding beam currents, as well as the minimum resolution. [picture]

[14] A graph showing the landing energy (curve 528) when the functionality is extended to 0.5 keV.

[0114] [picture]

[15] For applications with focusing lens arrays (such as...) [picture] Two use cases of the configuration of the focusing lens array described in [3] are compared, showing the resolution performance as a function of landing energy. It should be noted that in this type of configuration, the beam-limiting aperture that generates the sub-beams is in the opposite direction to the control lens array 250, meaning that the beam current is not affected by the control lens array 250 (as opposed to configurations without a focusing lens array, such as...). [picture]

[10] configuration) in contrast). For this reason, the data was not plotted as a function of beam current. The first use case is that, according to the configuration described above, the spatial relationship between the system's image plane and all control electrodes and objective lens electrodes remains the same across the landing energy range (curve 531). Curve 531 exists only for the lower part of the landing energy range because for higher landing energies, the electrostatic field must be increased above the feasible level. The second use case allows the image plane to move (with corresponding movement of the sample and detector modules) to achieve, as [picture] [4] The optimal resolution is depicted in the graph (curve 532). (Note that optimal resolution is the minimum resolvable size of the sub-beam at the sample location; for example, minimum resolution is the minimum resolvable size of the sub-beam at the sample location). Curves 531 and 532 diverge, with curve 531 showing lower resolution performance. However, the difference in performance is not significant, while the system complexity is greatly simplified. (Note that resolution performance is related to the resolvable size or size of the sub-beam at the sample location; the improved performance achieves a smaller resolvable size of the sub-beam at the sample location. Lower resolution performance is related to a larger resolvable size of the sub-beam at the sample location).

[0115] In some configurations, with [picture]

[13] and [picture] In contrast to the case illustrated in

[14] , resolution was intentionally not minimized. This removal of the constraint allows for a range of beam currents to be selected for each available landing beam energy. Therefore, the beam current can take other values, rather than being limited to a specific value corresponding to the specified landing beam energy. [picture]

[13] or [picture]

[14] One of the curves 523. A higher beam current can be selected at the cost of a larger (not optimal) resolution. By allowing the beam current to vary in this way, the system thus provides multiple selectable beam currents for each of one or more of the selectable landing beam energies. Therefore, in exchange for operating at a larger resolution, the range of selectable beam currents for the landing beam energy can be freely selected.

[0116] [picture]

[16] A graph illustrating four example curves (solid curves 524 to 527) showing how the beam current can be varied as described above. Each curve 524 to 527 corresponds to a different landing energy (524 = 2.5 keV, 525 = 2.0 keV, 526 = 1.5 keV, 527 = 1 keV) but with the same physical configuration (same aperture diameter and off-axis correction with hard-coded encoding) and the same image plane. Each curve 524 to 527 has a parabolic shape with a 90-degree rotation. In curve 527, both the upper and lower branches of the parabola are shown. In curves 524 to 526, only the upper branch (i.e., the branch where the beam current increases with increasing resolution) is shown for clarity, but there are two branches. The system can be configured to implement each selectable beam current by selecting the corresponding reduction ratio of the lens array 250. Each reduction ratio corresponds to a different beam current. [picture] In the example of

[16] , the different points on each of curves 524 to 527 correspond to different reduction rates. The reduction rate can be adjusted for each curve 524 to 527 to optimize the resolution. The resolution / current value with optimized resolution (for a given landing energy) is [picture] The point on curve 523 shown in

[14] . Alternatively, the reduction ratio can be adjusted to allow for resolution degradation while achieving a larger beam current. As described above, with the control lens array 250 comprising three control electrodes 501 to 503, each reduction ratio can be selected by applying a corresponding potential to the intermediate electrode 502 of the three control electrodes 501 to 503. Therefore, the system can be configured to implement each selectable beam current by applying a corresponding potential to the intermediate electrode 502 of the three control electrodes 501 to 503.

[0117] It is necessary for charged particle evaluation systems (including any of the systems described above) to selectively cut off one or more (or all) sub-beams. This may be desirable, for example, during the exchange of sample 208, during alignment, or during prolonged movement of sample 208. It is undesirable to cut off the sub-beams by disconnecting the charged particle source, for example, by making the anode potential equal to the cathode potential in the source or by lowering the source temperature. This action can lead to source instability, where the source tip shape varies depending on both the extraction field and temperature. An alternative is to deflect the sub-beams so that they do not pass through an aperture in the downstream direction of the source. The structure defining the aperture then blocks the sub-beams and acts as a blanking device. In some configurations, the deflected sub-beams can induce a localized surface potential change (which may be referred to as an exposure fingerprint) in the structure providing the blanking functionality. The localized surface potential change can be significant enough (e.g., approximately 1 V) and close enough to the aperture that the sub-beams will be affected when the system is restarted.

[0118] The above describes a system with an electro-optical column having both a control lens array 250 and an objective lens array 241. The control lens array 250 can be used in such systems to provide additional degrees of freedom to modify the overall reduction ratio and support changes in landing energy. The control lens array 241 typically does not operate within the limits of the maximum permissible electrostatic field strength, which allows the control lens array 241 to be operated to provide blocking modes.

[0119] Therefore, an evaluation system configured to guide charged particles in sub-beams arranged in a multi-beam configuration toward sample 208 can be provided. The evaluation system may include a series of lens electrodes arranged along the beam path to provide, for example, any of the configurations described above (e.g., referencing...). [picture] [3] [To the image]

[11] ) control lens array 250 and objective lens array 241. In one configuration, the system is configured (e.g., via controller 500) to apply a blocking mode by applying a blocking potential in one or more of the control lenses of the control lens array 250. The blocking potential causes charged particles entering one or more control lenses toward the sample 208 to be electrostatically reflected away from the sample 208. (Note: To select one or more of the lenses in the lens array, at least one of the lens electrodes is a plurality of electrodes on a plate, one of which can operate on one or more of the lenses in the array). The blocking potential cuts off the sub-beam corresponding to each control lens to which the blocking potential is applied. This functionality may also be referred to as blanking. If the blocking potential is applied to all control lenses (i.e., to the entire control lens array), all multi-beams can be cut off. This method allows for rapid and easy cut-off of the sub-beam with a low or negligible risk of exposure fingerprinting, because the sub-beam is not deflected into the structure near the aperture through which it would propagate when it is reconnected.

[0120] In a configuration where the control lens array 250 includes three control electrodes 501 to 503 aligned with the sub-beam paths of each sub-beam, the system can apply a blocking potential to at least the intermediate electrode 502 of the three control electrodes 501 to 503. A control electrode 501 further away from the sample 208 may be unsuitable because the potential applied to this electrode can be determined by the beam energy delivered by the source module. A control electrode 503 closer to the sample 208 may be unsuitable because it can be shared with the objective array and thus be at maximum field strength, or alternatively, it shares the same potential with most of the counter-current direction lens electrodes of the objective array and objective group. In a configuration where the control lens array 250 includes two control electrodes aligned with the sub-beam paths of each sub-beam, the system can apply a blocking potential to the control electrode closest to the sample 208.

[0121] The blocking functionality causes electrons to reflect away from the sample, and some of these electrons may return towards the source through the beam-limiting aperture array. However, the proportion of electrons reflected back to the source will be relatively low, due to, for example, the filtering effect of the beam-limiting aperture in both directions, and any effect on the source is expected to be negligible.

[0122] References to upper and lower, upward and downward, above and below, etc., in relation to embodiments containing or using particle interceptors should be understood as referring to directions parallel to the (usually, but not always vertical) countercurrent and cocurrent directions of the electron beam or multi-beam irradiating the sample 208. Therefore, references to countercurrent and cocurrent directions are intended to refer to directions independent of any current gravitational field relative to the beam path.

[0123] The embodiments described herein may take the form of a series of aperture arrays or electro-optical elements arranged in an array along a beam or multi-beam path. Such electro-optical elements may be electrostatic. In one embodiment, for example, all electro-optical elements in a sub-beam path prior to a sample, from the beam-limiting aperture array to the final electro-optical element, may be electrostatic and / or may be in the form of an aperture array or plate array. In some configurations, one or more of the electro-optical elements are fabricated as microelectromechanical systems (MEMS) (i.e., using MEMS fabrication techniques). The electro-optical elements may have both magnetic and electrostatic components. For example, a compound array lens may be characterized by a giant magnetic lens covering a multi-beam path, having upper and lower electrodes arranged within the magnetic lens and along the multi-beam path. An aperture array for the beam paths of the multi-beams may be present in these electrodes. Electrodes may be present above, below, or between these electrodes to control and optimize the electromagnetic field of the compound lens array.

[0124] In the case where electrodes are provided that can be set to different potentials relative to each other, it should be understood that such electrodes will be electrically isolated from each other. If the electrodes are mechanically connected to each other, an electrically insulating connector can be provided. For example, where the electrodes are provided as a series of conductive plates, each defining an aperture array, such as to form an array of objective lenses or control lenses, an electrically insulating plate can be provided between these conductive plates. The insulating plate can be connected to the conductive plates and thereby act as an insulating connector. The conductive plates can be separated from each other along the sub-beam path by means of the insulating plate.

[0125] The evaluation tool or system according to the present invention may include means for performing a qualitative evaluation of a sample (e.g., pass / fail), means for performing a quantitative measurement of a sample (e.g., size of a feature), or means for generating an image of a map of the sample. Examples of evaluation tools or systems are inspection tools (e.g., for identifying defects), inspection tools (e.g., for classifying defects), and metrology tools, or tools capable of performing any combination of evaluation functions associated with inspection tools, inspection tools, or metrology tools (e.g., metrology inspection tools).

[0126] Controllable manipulation of a charged particle beam by a reference frame of a component or system of components or elements includes: configuring a controller or control system or control unit to control the component to manipulate the charged particle beam as described, and, where appropriate, using other controllers or devices (e.g., voltage supply) to control the component thereby manipulating the charged particle beam in this manner. For example, a voltage supply may be electrically connected to one or more components to apply a potential to those components under the control of a controller or control system or control unit, such as to the electrodes of the control lens array 250 and objective lens array 241. Actuable components, such as a stage, may be controllable to actuate other components, such as the beam path, and thus move relative to those other components, such as the beam path, using one or more controllers, control systems, or control units to control the actuation of the component.

[0127] Functionality provided by a controller, control system, or control unit can be implemented via a computer. Any suitable combination of components can be used to provide the required functionality, including, for example, a CPU, RAM, SSD, motherboard, network connectivity, firmware, software, and / or other components known in the art that allow the execution of the required computational operations. The required computational operations can be defined by one or more computer programs. One or more computer programs can be provided in the form of media storing computer-readable instructions, or, where appropriate, non-transitory media. When the computer-readable instructions are read by the computer, the computer executes the required method steps. The computer can consist of a self-contained unit or a distributed computing system having multiple different computers interconnected via a network.

[0128] The terms "sub-beam" and "splitter" are used interchangeably herein and are both understood to encompass any radiation beam derived from the parent radiation beam by dividing or splitting it. The term "manipulator" is used to encompass any element that affects the path of a sub-beam or splitter, such as a lens or deflector. Reference to an element aligned along the beam path or sub-beam path should be understood to mean that the individual element is positioned along the beam path or sub-beam path. Reference to an optics device should be understood to mean an electro-optics device.

[0129] According to one aspect of the present invention, an evaluation system configured to guide charged particles in a multi-beam toward a specimen is provided. The system comprises: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being aligned with and configured to operate on a sub-beam path of a respective sub-beam of the multi-beam; and a plurality of objective lens electrodes defining and configured to guide the sub-beams onto a specimen, each objective lens in the objective lens array being aligned with a sub-beam path. A separate control lens alignment; and a controller, wherein the controller is configured to provide a plurality of selectable beam currents for a sub-beam, and to implement each selectable beam current by selecting a corresponding reduction ratio of one of the control lens arrays; and / or the controller is configured to: - implement a plurality of selectable landing energies for one of the multiple beams for a sub-beam by applying corresponding potentials to the control electrodes and the objective lens electrodes; and - when implementing the selected landing energies, apply potentials to the control electrodes to select the corresponding minimum resolution of the sub-beam on the sample.

[0130] According to one aspect of the present invention, an evaluation system is provided for guiding charged particles in a sub-beam arranged in a multi-beam configuration toward a sample. The system comprises: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being aligned with and configured to operate on a sub-beam of a respective sub-beam of the multi-beam configuration; a plurality of objective lens electrodes defining an objective lens array configured to guide the sub-beams onto a sample, each objective lens in the objective lens array being aligned with a sub-beam path, the sub-beam path being aligned with a respective control lens; and a controller configured to apply a blocking mode by applying a blocking potential in one or more of the control lenses, the blocking potential causing charged particles entering the one or more control lenses toward the sample during use to be electrostatically reflected away from the sample.

[0131] According to one aspect of the present invention, an evaluation system is provided for guiding charged particles in a sub-beam configured in a multi-beam configuration toward a sample. The system comprises: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being aligned with and configured to operate on a sub-beam of a respective sub-beam of the multi-beam configuration; and a plurality of objective lens electrodes defining and configured to guide the sub-beams onto a sample, each objective lens in the objective array being aligned with a sub-beam path, the sub-beam path being aligned with a respective control lens. Alignment; and a controller, wherein: the controller is configured to maintain a fixed spatial relationship between one image plane of the system and all of the control electrodes and objective lenses; and i) the control lens array is configured to be controllable to minimize the resolution of the multi-beam at the sample; ii) the controller is configured to control the control lens array to minimize the resolution of the multi-beam at the sample; and / or iii) the controller is configured to apply a selected potential to the control electrodes and objective lenses to control the control lens array to minimize the resolution of the multi-beam at the sample.

[0132] According to one aspect of the present invention, a method is provided for evaluating a sample by guiding charged particles in a sub-beam configured in a multi-beam configuration toward a sample using a system comprising: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being configured to operate on a separate sub-beam; and a plurality of objective lens electrodes defining and configured to guide the sub-beams to an objective lens array on a sample, each objective lens being configured to operate on a sub-beam from a separate control lens of the control lens array. The method comprises selecting a plurality of different landing energies for one of the sub-beams of the multi-beam configuration at different times, each landing energy being selected by applying a corresponding potential to the control electrodes and the objective lens electrodes, wherein the corresponding potentials are selected such that a spatial relationship between an image plane of the system and all the control electrodes and objective lens electrodes is the same for each of the different landing energies.

[0133] According to one aspect of the present invention, a method is provided for an evaluation system that uses charged particles in a sub-beam configured in a multi-beam configuration to guide toward a sample. The system includes control electrodes for operating one of the multi-beam sub-beams and objective electrodes for focusing the sub-beams onto an image plane, the image plane having a fixed spatial relationship with all the control electrodes and objective electrodes. The method includes: applying a plurality of selectable landing energies to one of the sub-beams, the application including applying corresponding potentials to the control electrodes and objective electrodes; and selecting the corresponding potentials that give the fixed spatial relationship.

[0134] According to one aspect of the present invention, a method is provided for evaluating a sample by guiding charged particles in a sub-beam configured in a multi-beam configuration toward a sample using a system comprising: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being configured to operate on a separate sub-beam; and a plurality of objective lens electrodes defining and configured to guide the sub-beams to an objective lens array on a sample, each objective lens being configured to operate on a sub-beam from a separate control lens of the control lens array. The method comprises: selecting a plurality of different beam currents for a sub-beam of the multi-beam configuration at different times, each beam current being implemented by selecting a corresponding reduction ratio of the control lens array; and / or applying a plurality of selectable landing energies to the sub-beam of the multi-beam configuration by applying corresponding potentials to the control electrodes and the objective lens electrodes, until the potentials of the control electrodes are selected to minimize the resolution of the sub-beam on the sample.

[0135] According to one aspect of the present invention, a method is provided for evaluating a sample by guiding charged particles in a multi-beam configuration toward a sample using a system comprising: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being configured to operate on a separate sub-beam; and a plurality of objective lens electrodes defining and configured to guide the sub-beams to an objective lens array on a sample, each objective lens being configured to operate on a sub-beam from a separate control lens of the control lens array. The method comprises applying a blocking mode by applying a blocking potential in one or more of the control lenses, the blocking potential causing charged particles entering the one or more control lenses toward the sample to be electrostatically reflected away from the sample.

[0136] According to one aspect of the present invention, a method is provided for evaluating a sample by guiding charged particles in a multi-beam configuration toward a sample using a system. The system includes: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being configured to operate on a separate sub-beam; and a plurality of objective lens electrodes defining and configured to guide the sub-beams to an objective lens array on a sample, each objective lens being configured to operate on a sub-beam from a separate control lens of the control lens array. The method includes: while maintaining a fixed spatial relationship between an image plane of the system and all the control electrodes and objective lens electrodes; controlling the control lens array to minimize the resolution of the multi-beams at the sample; and / or applying a selected potential to the control electrodes and the objective lens electrodes to control the control lens array, thereby minimizing the resolution of the multi-beams at the sample.

[0137] According to one aspect of the present invention, an evaluation system is provided configured to guide charged particles in a sub-beam arranged in a multi-beam configuration toward a sample. The system comprises: at least four lens electrodes orthogonal to the sub-beam paths of the multi-beam configuration and / or arranged in series along the sub-beam paths and configured to operate on the sub-beams along the sub-beam paths; a control lens array comprising at least two of the lens electrodes and including a most downstream direction electrode in the downstream direction of all other lens electrodes in the control lens array; and an objective lens array comprising at least two of the lens electrodes and including the most downstream direction electrode of the control lens array as the most upstream direction electrode of the objective lens array, wherein the most downstream direction electrode of the control lens array comprises an upstream direction surface and a downstream direction surface, the downstream direction surface comprising a portion of the objective lens array and the upstream direction surface comprising a portion of the control lens array.

[0138] According to one aspect of the present invention, an evaluation system is provided configured to guide charged particles in a sub-beam arranged in a multi-beam configuration toward a sample. The system comprises: at least three, preferably at least four lens electrodes orthogonal to the sub-beam paths of the multi-beam configuration and / or arranged in series along the sub-beam paths and configured to operate on the sub-beams along the sub-beam paths; at least two of a plurality of countercurrent direction electrodes provide a control lens array, thereby providing a plurality of control electrodes for the control lens array; and at least two of a plurality of downstream direction electrodes provide an objective lens array, thereby providing a plurality of objective lens electrodes for the objective lens array; the most downstream direction electrode of the control lens array is identical to the most countercurrent direction electrode of the objective lens array, such that the countercurrent direction surface of the most downstream direction electrode of the control lens array includes a portion of the control lens array, and the downstream direction surface of the electrode includes a portion of the objective lens array.

[0139] According to one aspect of the present invention, an evaluation system is provided for guiding charged particles in a sub-beam configured in a multi-beam configuration toward a sample. The system includes: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being aligned with and configured to operate on a sub-beam of a respective sub-beam of the multi-beam configuration; and a plurality of objective lens electrodes defining an objective lens array configured to guide the sub-beams onto a sample, each objective lens in the objective lens array being aligned with a sub-beam path, the sub-beam path being aligned with a respective control lens. The system is configured to apply a plurality of selectable landing energies to a sub-beam of the multi-beam configuration by applying corresponding potentials to the control electrodes and the objective lens electrodes. The system is also configured to select the corresponding potentials such that a spatial relationship between an image plane of the system and all the control electrodes and objective lens electrodes is the same for each of the selectable landing energies.

[0140] Multiple items are provided: Clause 1: An evaluation system configured to guide charged particles in a sub-beam arranged in a multi-beam configuration toward a sample, the system comprising: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being aligned with and configured to operate on a sub-beam of a respective sub-beam of the multi-beam configuration; a plurality of objective lenses defining an objective array configured to guide the sub-beams onto a sample, each objective lens in the objective array being aligned with a sub-beam path, the sub-beam path being aligned with a respective control lens; and a controller configured to apply a plurality of selectable landing energies to a sub-beam of the multi-beam configuration by applying corresponding potentials to the control electrodes and the objective lenses, wherein: the controller is configured to select the corresponding potentials such that a spatial relationship between an image plane of the system and all the control electrodes and objective lenses is the same for each of the selectable landing energies. Ideally, the controller is configured to apply potentials to the control electrodes and the objective lens electrodes. Ideally, the applied potentials are selected to maintain the same spatial relationship between an image plane and, where appropriate, all the control electrodes and objective lens electrodes. Ideally, the plurality of selectable landing energy systems are implemented by the controller by applying corresponding potentials to the control electrodes and the objective lens electrodes (e.g., via individual potential sources). Different potentials can be applied for each selectable landing energy system.

[0141] Clause 2: A system as described in Clause 1, configured to receive user input, wherein the controller is configured to select the optional landing energies at least in part based on the received user input.

[0142] Clause 3: A system as described in Clause 1 or 2, wherein the controller is configured to select the optional landing energies based at least in part on a predefined program or one or more input parameters.

[0143] Clause 4: The system of any of the preceding clauses, wherein the plurality of selectable landing energies comprises at least one continuous range of landing energies or a plurality of predetermined discrete landing energies.

[0144] Clause 5: A system as described in any of the preceding clauses, wherein the controller is configured to apply the same potential to a portion of the control electrode configured to be furthest from the sample and aligned with the sub-beam path of the sub-beam for at least a portion of the selectable landing energies.

[0145] Clause 6: A system as described in any of the preceding clauses, wherein the controller is configured to apply a different potential to an objective electrode configured to be furthest from the sample and aligned with the sub-beam path of the sub-beam for each of at least a portion of the selectable landing energies, wherein each potential is selected to provide the same distance between the objective electrode and one of the image planes of the system.

[0146] Clause 7: A system as described in any of the preceding clauses, wherein the controller is configured to select each selectable landing beam energy by controlling the application of a potential to at least one of the objective electrodes configured to be closest to the sample and as part of the sub-beam path aligned with the sub-beam.

[0147] Clause 8: A system as described in any of the preceding clauses, wherein the controller is configured to control the control lens array to: minimize, for example, the resolution of the sub-beam on the sample for each of the plurality of selectable landing energies; or minimize the resolved or resolvable size of the sub-beam on the sample for each of the plurality of selectable landing energies.

[0148] Clause 9: A system as described in any of Clauses 1 to 7, wherein the controller is configured to provide a plurality of selectable beam currents for one of the selectable landing beam energies or for each of the plurality of selectable landing beam energies.

[0149] Clause 10: A system as described in Clause 9, wherein the controller is configured to implement each selectable beam current by selecting a corresponding reduction ratio of one of the control lens arrays.

[0150] Clause 11: The system as described in Clause 9, wherein for each selectable beam current, the controller is configured to control the control lens aligned with the sub-beam path of the sub-beam to select one of the corresponding reduction ratios of the system.

[0151] Clause 12: An evaluation system configured to guide charged particles in a multi-beam toward a sample, the system comprising: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being aligned with and configured to operate on a sub-beam path of a respective sub-beam of the multi-beam; a plurality of objective lens electrodes defining an objective array configured to guide the sub-beams onto a sample, each objective lens in the objective array being aligned with a sub-beam path, the sub-beam path being aligned with a respective sub-beam path. A control lens alignment; and a controller, wherein the controller is configured to provide a plurality of selectable beam currents for a sub-beam, and each selectable beam current is implemented by selecting a corresponding reduction ratio of one of the control lens arrays; and / or the controller is configured to: - implement a plurality of selectable landing energies for one of the multiple beams for a sub-beam by applying corresponding potentials to the control electrodes and the objective lens electrodes; and - when implementing the selected landing energies, apply potentials to the control electrodes to select the corresponding minimum resolution of the sub-beam on the sample.

[0152] Clause 13: A system as described in any of Clauses 9 to 12, wherein: the control lens array includes three control electrodes aligned with the sub-beam path of the sub-beam; and the controller is configured to implement each selectable beam current by applying a corresponding potential to the intermediate electrode of the three control electrodes.

[0153] Clause 14: In any of the preceding clauses, the objective electrode configured to be furthest from the sample and as part of the sub-beam path aligned with the sub-beam, and the control electrode configured to be closest to the sample and as part of the control lens aligned with the sub-beam path, are provided by a common electrode.

[0154] Clause 15: A system as described in any of the preceding clauses, wherein the controller is configured to apply a blocking mode by applying a blocking potential in one or more of the control lenses, the blocking potential causing charged particles entering the one or more control lenses toward the sample during use to be electrostatically reflected away from the sample.

[0155] Clause 16: An evaluation system configured to guide charged particles in a sub-beam arranged in a multi-beam configuration toward a sample, the system comprising: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being aligned with and configured to operate on a sub-beam path of a respective sub-beam of the multi-beam configuration; a plurality of objective electrode bases defining an objective array configured to guide the sub-beams onto a sample, each objective lens in the objective array being aligned with a sub-beam path, the sub-beam path being aligned with a respective control lens; and a controller configured to apply a blocking mode by applying a blocking potential in one or more of the control lenses, the blocking potential causing charged particles entering the one or more control lenses toward the sample during use to be electrostatically reflected away from the sample.

[0156] Clause 17: A system as described in Clause 15 or 16, wherein: the control lens array includes three control electrodes aligned with the path of each sub-beam; and the system is configured to apply the blocking mode by applying the blocking potential to at least the intermediate control electrode of the three control electrodes.

[0157] Clause 18: A system as described in Clause 15 or 16, wherein: the control lens array includes two control electrodes aligned with the path of each sub-beam; and the system is configured to apply the blocking mode by applying the blocking potential to the control electrode configured to be closest to the sample.

[0158] Clause 19: The system of any of the preceding clauses, wherein the control electrodes are arranged in series along the sub-beam paths and define individual apertures aligned with the sub-beam paths to define the control lenses.

[0159] Clause 20: A system as described in Clause 19, wherein each control electrode is configured to operate all of the sub-beams of the multi-beam.

[0160] Clause 21: An evaluation system configured to guide charged particles in a sub-beam arranged in a multi-beam configuration toward a sample, the system comprising: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being aligned with and configured to operate on a sub-beam of a respective sub-beam of the multi-beam configuration; a plurality of objective electrode terminals defining an objective array configured to guide the sub-beams onto a sample, each objective lens in the objective array being aligned with a sub-beam path, the sub-beam path being aligned with a respective control lens; The system includes a controller configured to maintain a fixed spatial relationship between an image plane of the system and all of the control electrodes and objective lenses; and i) the control lens array is configured to be controllable to minimize the resolution of the multi-beam at the sample; ii) the controller is configured to control the control lens array to minimize the resolution of the multi-beam at the sample; and / or iii) the controller is configured to apply a selected potential to the control electrodes and objective lenses to control the control lens array to minimize the resolution of the multi-beam at the sample.

[0161] Clause 22: The system of Clause 21, wherein: the controller is configured to apply a plurality of selectable landing energies to one of the multiple beams by applying corresponding potentials to the control electrodes and the objective lens electrodes; and the controller is configured to minimize the resolution for each of the selectable landing energies by controlling the reduction rate of the control lens array.

[0162] Clause 23: A method for evaluating a sample by guiding charged particles in a sub-beam configured in a multi-beam configuration toward a sample using a system comprising: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being configured to operate on a separate sub-beam; and a plurality of objective lenses defined and configured to guide the sub-beams to an objective lens array on a sample, each objective lens being configured to operate on a sub-beam from a separate control lens of the control lens array, the method comprising: selecting a plurality of different landing energies for one of the sub-beams of the multi-beam configuration at different times, each landing energy being selected by applying a corresponding potential to the control electrodes and the objective lenses, wherein the corresponding potentials are selected such that a spatial relationship between an image plane of the system and all the control electrodes and objective lenses is the same for each of the different landing energies.

[0163] Clause 24: A method for using an evaluation system that guides charged particles in a sub-beam configured in a multi-beam configuration toward a sample, the system comprising control electrodes for operating one of the multi-beam sub-beams and objective electrodes for focusing the sub-beams onto an image plane, the image plane having a fixed spatial relationship with all of the control electrodes and objective electrodes, the method comprising: applying a plurality of selectable landing energies to one of the sub-beams of the multi-beam configuration, the application comprising applying corresponding potentials to the control electrodes and objective electrodes; and selecting the corresponding potentials that give the fixed spatial relationship.

[0164] Clause 25: A method for evaluating a sample by guiding charged particles in a sub-beam configured in a multi-beam configuration toward a sample using a system comprising: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being configured to operate on a separate sub-beam; and a plurality of objective lens electrodes defining and configured to guide the sub-beams to an objective lens array on a sample, each objective lens being configured to operate on a sub-beam from a separate control lens of the control lens array, the method comprising: selecting a plurality of different beam currents for a sub-beam of the multi-beam configuration at different times, each beam current being implemented by selecting a corresponding reduction ratio of the control lens array; and / or applying a plurality of selectable landing energies to the sub-beam of the multi-beam configuration by applying corresponding potentials to the control electrodes and the objective lens electrodes, wherein the potentials of the control electrodes are selected to minimize the resolution of the sub-beam on the sample.

[0165] Clause 26: A method for evaluating a sample by guiding charged particles in a multi-beam configuration toward a sample using a system comprising: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being configured to operate on a separate sub-beam; and a plurality of objective lens electrodes defined and configured to guide the sub-beams toward an objective lens array on a sample, each objective lens being configured to operate on a sub-beam from a separate control lens of the control lens array, the method comprising: applying a blocking mode by applying a blocking potential in one or more of the control lenses, the blocking potential causing charged particles entering the one or more control lenses toward the sample to be electrostatically reflected away from the sample.

[0166] Clause 27: A method for evaluating a sample by guiding charged particles in a multi-beam configuration toward a sample using a system comprising: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being configured to operate on a separate sub-beam; and a plurality of objective lenses defined and configured to guide the sub-beams toward an objective array on a sample, each objective lens being configured to operate on a sub-beam from a separate control lens of the control lens array, the method comprising: while maintaining a fixed spatial relationship between an image plane of the system and all the control electrodes and objective lenses; controlling the control lens array to minimize the resolution of the multi-beams at the sample; and / or applying a selected potential to the control electrodes and the objective lenses to control the control lens array, thereby minimizing the resolution of the multi-beams at the sample.

[0167] Clause 28: The method of any of Clauses 23 to 27 further comprises detecting signal electrons emitted from the sample.

[0168] Clause 29: An evaluation system configured to guide charged particles in a sub-beam arranged in a multi-beam configuration toward a sample, the system comprising: at least four lens electrodes orthogonal to the sub-beam paths of the multi-beam configuration and / or arranged in series along the sub-beam paths and configured to operate on the sub-beams along the sub-beam paths; a control lens array comprising at least two of the lens electrodes and including a most downstream direction electrode in the downstream direction of all other lens electrodes in the control lens array; and an objective lens array comprising at least two of the lens electrodes and including the most downstream direction electrode of the control lens array as the most upstream direction electrode of the objective lens array, wherein the most downstream direction electrode of the control lens array includes a downstream direction surface and a downstream direction surface, the downstream direction surface including a portion of the objective lens array and the downstream direction surface including a portion of the control lens array.

[0169] Clause 30: An evaluation system configured to guide charged particles in a sub-beam arranged in a multi-beam configuration toward a sample, the system comprising: at least three, preferably at least four lens electrodes orthogonal to the sub-beam paths of the multi-beam configuration and / or arranged in series along the sub-beam paths and configured to operate on the sub-beams along the sub-beam paths; at least two of a plurality of countercurrent direction electrodes providing a control lens array thereby providing a plurality of control electrodes providing the control lens array; and at least two of a plurality of downstream direction electrodes providing an objective lens array thereby providing a plurality of objective lens electrodes providing the objective lens array; the most downstream direction electrode of the control lens array being identical to the most countercurrent direction electrode of the objective lens array, such that the countercurrent direction surface of the most downstream direction electrode of the control lens array includes a portion of the control lens array, and the downstream direction surface of the electrode includes a portion of the objective lens array.

[0170] Clause 31: The system of Clause 29 or 30 further includes a controller configured to apply a selected potential to the control electrodes and the objective electrodes in order to control the control lens array and the objective lens array.

[0171] Clause 32: A system as described in Clause 31, wherein the controller is configured such that the system performs the method described in any of Clauses 23 to 28.

[0172] Clause 33: An evaluation system configured to guide charged particles in a sub-beam arranged in a multi-beam configuration toward a sample, the system comprising: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being aligned with and configured to operate on a sub-beam of a respective sub-beam of the multi-beam configuration; and a plurality of objective lenses defining an objective array configured to guide the sub-beams onto a sample, each objective lens in the objective array being aligned with a sub-beam path, the sub-beam path being aligned with a respective control lens, wherein the system is configured to apply a plurality of selectable landing energies to a sub-beam of the multi-beam configuration by applying corresponding potentials to the control electrodes and the objective lenses; and the system is configured to select the corresponding potentials such that a spatial relationship between an image plane of the system and all the control electrodes and objective lenses is identical for each of the selectable landing energies.

[0173] Clause 34: An evaluation system configured to guide charged particles in a multi-beam toward a specimen, the system comprising: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being aligned with and configured to operate on a sub-beam path of a respective sub-beam of the multi-beam; and a plurality of objective electrode bases defining an objective array configured to guide the sub-beams onto a specimen, each objective lens in the objective array being aligned with a sub-beam path, the sub-beam path being... Aligned with a separate control lens, wherein: the system is configured to provide a plurality of selectable beam currents for a sub-beam, and each selectable beam current is implemented by selecting a corresponding reduction ratio of one of the control lens arrays; and / or the system is configured to: - implement a plurality of selectable landing energies for one of the multiple beams for a sub-beam by applying corresponding potentials to the control electrodes and the objective lens electrodes; and - when implementing the selected landing energies, apply potentials to the control electrodes to select the corresponding minimum resolution of the sub-beam on the sample.

[0174] Clause 35: An evaluation system configured to guide charged particles in a sub-beam arranged in a multi-beam configuration toward a sample, the system comprising: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being aligned with and configured to operate on a sub-beam path of a respective sub-beam of the multi-beam configuration; and a plurality of objective lens electrodes defining an objective lens array configured to guide the sub-beams onto a sample, each objective lens in the objective lens array being aligned with a sub-beam path, the sub-beam path being aligned with a respective control lens, wherein: the system is configured to apply a blocking mode by applying a blocking potential in one or more of the control lenses, the blocking potential causing charged particles entering the one or more control lenses toward the sample during use to be electrostatically reflected away from the sample.

[0175] Clause 36: An evaluation system configured to guide charged particles in a sub-beam arranged in a multi-beam configuration toward a sample, the system comprising: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being aligned with and configured to operate on a sub-beam path of a respective sub-beam of the multi-beam configuration; and a plurality of objective lens electrodes defining an objective lens array configured to guide the sub-beams toward a sample, each objective lens in the objective lens array being aligned with a sub-beam path, the sub-beam path being aligned with a respective control lens path. Lens alignment, wherein: the system is configured to maintain a fixed spatial relationship between one of the image planes of the system and all of the control electrodes and objective lenses; and i) the control lens array is configured to be controllable to minimize the resolution of the multi-beam at the sample; ii) the system is configured to control the control lens array to minimize the resolution of the multi-beam at the sample; and / or iii) the system is configured to apply a selected potential to the control electrodes and objective lenses to control the control lens array to minimize the resolution of the multi-beam at the sample.

[0176] Clause 37: An evaluation system configured to guide charged particles in a sub-beam arranged in a multi-beam configuration toward a sample, the system comprising: a plurality of control electrodes defining a control lens array, each control lens in the control lens array being aligned with and configured to operate on a sub-beam of a respective sub-beam of the multi-beam configuration; a plurality of objective electrodes defining an objective array configured to guide the sub-beams onto a sample, each objective in the objective array being aligned with a sub-beam path, the sub-beam path being aligned with a respective control lens; and a controller configured to apply a selected potential to the objective electrodes and the control electrodes. To control the beam energy of each sub-beam, i) to control the control electrodes and / or objective electrodes such that the control of the reduction rate causes a change in resolution relative to the total current of each sub-beam; ii) to control the reduction rate of the control electrodes and / or objective electrodes so as to preferably minimize the resolution of each sub-beam of the multi-beam at the sample while changing the landing energy; and / or iii) to apply a selected potential to the control electrodes and / or objective electrodes so as to preferably maintain the focus of each sub-beam in the image plane of the system while changing the landing energy, the image plane of the system having a fixed spatial relationship with all the control electrodes and objective electrodes.

[0177] Clause 38: The system of Clause 37, wherein the image plane of the system has a fixed spatial relationship with all such control electrodes and objective lens electrodes.

[0178] Clause 39: A system as described in Clause 37 or 38, wherein the controller is verified to maintain the fixed spatial relationship.

[0179] Although the invention has been described in conjunction with various embodiments, other embodiments of the invention will become apparent to those skilled in the art from consideration of this specification and from the practice of the invention disclosed herein. This specification and examples are intended to be illustrative only, wherein the true scope and spirit of the invention are indicated by the following claims.

[0180] 10:Main chamber 20: Loading locking chamber 30: Equipment Front-End Module (EFEM) 30a: First loading port 30b: Second loading port 40: Electron Beam Tools 50: Controller 100: Exemplary charged particle beam detection device 201: Electron source / beam source 202: Primary Electron Beam 207: Sample Holder 208: Sample 209: Mobile Platform 211: Primary Sub-beam 212: Primary Sub-beam 213: Primary Sub-beam 221: Detecting the light spot 222: Detecting the light spot 223: Detecting the light spot 230: Projection device 231: Condensing lens / Condensing lens array 234: Objective lens / objective lens array 235: Deflector 240: Electronic detection devices 241: Objective lens array 242: Beam Shaping Limiter 250: Control lens array 252: Upper beam limiter 260: Scan deflector / scan deflector array 265: Giant Scan Deflector 270: Giant Collimator 300: Objective lens 301: Intermediate or first electrode 302: Lower or second electrode 303: Upper or third electrode 401: Multibeam Objective Lens 402: Detector Module 404: Substrate / Silicon Substrate 405: Detector element / capture electrode 406: Beam Aperture 407: Logic Layer 408: Wiring Layer 409: Silicon perforation 500: Controller 501: Control Electrode 502: Control electrode / intermediate electrode 503: Control electrode / Objective electrode / Common electrode 504: Objective lens electrode 510: Sub-beam path 521: Curve 522: Curve 523: Solid line curve 524: Solid line curve 525: Solid line curve 526: Solid line curve 527: Solid line curve 528: Curve 531: Curve 532: Curve 600: Control Lens 601: Intermediate electrode 602: Lower electrode 603: Top electrode V1: Voltage source V2: Voltage source V3: Voltage source V4: Voltage source V5: Potential Source V6: Potential Source V7: Potential Source

Claims

1. An evaluation system configured to guide charged particles in a sub-beam arranged in a multi-beam configuration toward a sample, the system comprising: an objective array assembly configured to guide the sub-beams toward a sample, the objective array assembly comprising: a focusing lens array having a plurality of focusing electrodes; a pre-focusing lens array having a plurality of pre-focusing electrodes for pre-focusing the sub-beams before they pass through the focusing lens array; a detector array; and a controller configured to apply a plurality of selectable landing energies to one of the sub-beams of the multi-beam configuration by applying corresponding potentials to the pre-focusing electrodes and the focusing electrodes, wherein the controller is configured to select the corresponding potentials such that the detection efficiency of one of the detector arrays is optimized for each of the plurality of selectable landing energies.

2. The system of request item 1, which is configured to receive user input, wherein the controller is configured to select the optional landing energies at least in part based on the received user input.

3. The system of request item 1 or 2, wherein the controller is configured to select the optional landing energies at least in part based on a predefined program or one or more input parameters.

4. The system of request item 1 or 2, wherein the plurality of selectable landing energies comprises at least one continuous range of landing energies or a plurality of predetermined discrete landing energies.

5. The system of claim 1 or 2, wherein the controller is configured to apply the same potential to a pre-focusing electrode configured to be furthest from the sample for at least a portion of the optional landing energies.

6. The system of claim 1 or 2, wherein the controller is configured to apply a different potential to a focusing electrode configured to be furthest from the sample for each of at least a portion of the selectable landing energies, each potential being selected to optimize the detection efficiency of one of the detector arrays.

7. The system of claim 1 or 2, wherein the controller is configured to select each selectable landing beam energy by controlling the application of a potential to at least one of the focusing electrodes configured to be closest to the sample.

8. The system of claim 1 or 2, wherein the controller is configured to control the prefocusing lens array to minimize the resolvable size of the sub-beam on the sample for each of the plurality of selectable landing energies.

9. The system of claim 1 or 2, wherein the controller is configured to provide a plurality of selectable beam currents for one of the selectable landing beam energies or for each of the plurality of selectable landing beam energies.

10. The system of claim 9, wherein the controller is configured to implement each selectable beam current by selecting a corresponding reduction ratio of the prefocusing lens array.

11. The system as described in request item 9, wherein, For each selectable beam current, the controller is configured to control one of the prefocusing lenses in the prefocusing lens array aligned with one of the sub-beam paths of a sub-beam to select one of the corresponding reduction ratios of the system.

12. The system as described in request item 9, wherein: The prefocusing lens array includes three prefocusing electrodes aligned with the sub-beam path of the sub-beam; and the controller is configured to implement each selectable beam current by applying a corresponding potential to the middle electrode of the three prefocusing electrodes.

13. The system of claim 1 or 2, wherein the focusing electrode configured to be furthest from the sample and the pre-focusing electrode configured to be closest to the sample are provided by a common electrode.

14. The system of claim 1 or 2, wherein the controller is configured to apply a blocking mode by applying a blocking potential within one or more pre-focusing lenses of the pre-focusing lens array, the blocking potential causing charged particles entering the one or more pre-focusing lenses toward the sample during use to be electrostatically reflected away from the sample.

15. A method for an evaluation system that guides charged particles in a sub-beam configured in a multi-beam configuration toward a sample, the system comprising an objective array assembly having a plurality of pre-focusing electrodes, a plurality of focusing electrodes, and a detector array, wherein the pre-focusing electrodes are configured to pre-focus the sub-beams before they pass through the focusing electrodes, the method comprising: applying a plurality of selectable landing energies to one of the sub-beams of the multi-beam configuration, the application comprising applying corresponding potentials to the pre-focusing electrodes and the focusing electrodes; and selecting the corresponding potentials such that the detection efficiency of one of the detector arrays is optimized for each of the plurality of selectable landing energies.

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