Electrooptical plate

Abstract

The invention relates to a charged particle optical plate for a charged particle optical device for projecting a charged particle beam along a beam path to a sample location. A charged particle optical plate includes: a substrate having a crystal structure having a crystal symmetry line; a plurality of channels configured for passing a plurality of beam paths of a beam grid through the substrate; and a plurality of multipoles associated with a respective channel, each multipole comprising a plurality of electrodes for the associated channel, where the electrodes are arranged such that a geometric symmetry line of the multipole is parallel to a respective crystal symmetry line of the crystal structure.

Description

Cross Reference to Related Applications

[0001] This application claims priority to EP application 23164395.8, filed on 27 March 2023, which is incorporated herein in its entirety by reference. TECHNICAL FIELD

[0002] The present disclosure relates to a charged-particle optical plate for steering one or more charged-particle beams, a charged-particle optical assembly comprising the plate, a charged-particle optical stack comprising the plate, a charged-particle optical module comprising the plate, a charged-particle optical device comprising the plate, a charged-particle optical device comprising the plate, and a method of manufacturing the plate. BACKGROUND

[0003] When manufacturing semiconductor integrated circuit (IC) chips, unwanted pattern defects inevitably occur on a substrate (i.e. wafer) or mask during the manufacturing process as a result of, for example, optical effects and incidental particles, thereby reducing the yield. Therefore, monitoring the extent of unwanted pattern defects is an important process in manufacturing IC chips. More generally, inspection and / or measurement of, for example, a surface of a substrate or other object / material is an important process during and / or after its manufacture.

[0004] Pattern evaluation systems, for example, pattern inspection tools having a charged-particle beam, have been used to evaluate objects, for example, for detecting pattern defects. These tools typically use electron microscopy techniques, for example, scanning electron microscopy (SEM). In a SEM, a primary electron beam of electrons having a relatively high energy is targeted with a final deceleration step in order to land on a target with a relatively low landing energy. The electron beam is focused on the target as a probe spot. The interaction between the material structure at the probe spot and the landing electrons from the electron beam causes electrons to be emitted from the surface, for example, secondary electrons, backscattered electrons or Auger electrons, which together can be referred to as signal electrons or more generally as signal particles. The signal electrons can be emitted from the material structure of the sample. By scanning the primary electron beam as a probe spot over the sample surface, signal electrons can be emitted over the sample surface. By collecting these emitted signal electrons from the sample surface, an image representative of the features of the material structure of the sample surface can be obtained.

[0005] Electro-optical plates for electro-optical devices can be used to control electron beams. Electro-optical plates define features such as apertures for influencing electron trajectories, for example by providing lensing effects, deflection and / or correction effects (e.g., astigmatism and / or higher order). Electro-optical plates can be multi-pole arrays in which the surface of the features in the plate comprises a plurality of electrodes that can be controlled to deflect the paths of the beams relative to one another. Various aspects of the features can influence the performance of the electro-optical stack, for example the shape, size and / or position of the features. Defects in the manufacturing process for manufacturing the features, for example unintended structural features that are created during processing steps, can degrade the performance of the electro-optical plate. SUMMARY

[0006] It is an object of the present disclosure to provide apparatuses and methods that facilitate improving the electro-optical performance of electro-optical plates, as well as electro-optical stacks and devices comprising such electro-optical plates.

[0007] According to an aspect of the present invention, there is provided an electro-optical plate for a charged-particle optical device for projecting a charged-particle beam along a beam path to a sample location, the electro-optical plate comprising: a substrate having a crystal structure, the crystal structure having crystal symmetry lines; a plurality of channels configured for a plurality of beam paths of a beam grid to pass through the substrate; and a plurality of multi-poles associated with respective channels, each multi-pole comprising a plurality of electrodes for the associated channel, wherein the electrodes are arranged such that a geometric symmetry line of the multi-pole is parallel to respective crystal symmetry lines of the crystal structure.

[0008] According to an aspect of the present invention, there is provided an electro-optical plate for a charged-particle optical device for projecting a charged-particle beam along a beam path to a sample location, the electro-optical plate comprising: a substrate having a crystal structure, the crystal structure having crystal symmetry lines; a channel configured for one beam path of a charged-particle to pass through the substrate; and a multi-pole associated with the channel, the multi-pole comprising a plurality of electrodes for the channel, wherein the electrodes are arranged such that a geometric symmetry line of the multi-pole is parallel to respective crystal symmetry lines of the crystal structure.

[0009] According to an aspect of the present invention, there is provided an electro-optical assembly comprising: an electro-optical plate; and a power supply configured to apply an electric potential to the electrodes.

[0010] According to an aspect of the present invention, there is provided an electro-optical stack comprising: at least one charged-particle optical plate or at least one charged-particle optical assembly.

[0011] According to an aspect of the present application, there is provided a charged-particle optical module comprising at least one of a charged-particle optical plate, a charged-particle optical assembly and a charged-particle optical stack.

[0012] According to an aspect of the present application, there is provided a charged-particle optical device for projecting a charged-particle beam along a beam path to a sample location, the charged-particle optical device comprising at least one of a charged-particle optical plate, a charged-particle optical assembly, a charged-particle optical stack and a charged-particle optical module.

[0013] According to an aspect of the present application, there is provided a charged-particle optical device comprising at least one of a charged-particle optical plate, a charged-particle optical assembly, a charged-particle optical stack, a charged-particle optical module and a charged-particle optical assembly.

[0014] According to an aspect of the present application, there is provided a method of manufacturing a charged-particle optical plate for a charged-particle optical device for projecting a charged-particle beam along a beam path to a sample location, the method comprising: providing a substrate having a crystal structure; forming a plurality of channels for the beam path through the substrate; and forming a plurality of multipoles associated with respective channels, each multipole comprising a plurality of electrodes for the associated channel, wherein the electrodes are arranged such that a line of symmetry of the multipole is parallel to a respective line of symmetry of the crystal structure of the substrate.

[0015] According to an aspect of the present application, there is provided a method of manufacturing a charged-particle optical plate for a charged-particle optical device for projecting a charged-particle beam along a beam path to a sample location, the method comprising: forming a plurality of channels for the beam path of a plurality of beams through a substrate having a crystal structure, the crystal structure having a desired line of crystal symmetry between two major sides of the substrate; and forming a plurality of multipoles, each multipole being associated with a respective channel, each multipole comprising a plurality of electrodes for the associated channel, the multipole having a line of geometric symmetry of the electrodes relative to the channel, wherein forming the multipole comprises positioning the electrodes relative to the channel such that the line of geometric symmetry is parallel to a respective line of symmetry of the crystal structure of the substrate. BRIEF DESCRIPTION OF DRAWINGS

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

[0017] Figure 1is a schematic diagram illustrating an example charged particle beam inspection apparatus.

[0018] Figure 2 is a schematic diagram of an example multi-beam apparatus that forms part of an example charged particle beam inspection apparatus of Figure 1 .

[0019] Figure 3 is a schematic diagram of an example electron-optical arrangement comprising a condenser lens array, an objective lens array and a detector array.

[0020] Figure 4 is a schematic cross-sectional view of part of an example objective lens array and detector array arrangement.

[0021] Figure 5 is a bottom view of part of a detector array of Figure 4 .

[0022] Figure 6 is a bottom view of a modified version of part of an objective lens array of Figure 4 .

[0023] Figure 7 is a schematic diagram of an example electron-optical arrangement comprising an objective lens array and a beam separator.

[0024] Figure 8 is a diagram of a further example electron-optical arrangement.

[0025] Figure 9 is a schematic diagram of an example electron-optical stack that can be part of an electron-optical arrangement such as Figure 3 , Figure 7 and Figure 8 .

[0026] Figure 10 is a schematic perspective view of three plates of an example electron-optical stack.

[0027] Figure 11 is a schematic side view showing an embodiment of circuitry at a feature of an electron-optical plate.

[0028] Figure 12 is a schematic plan view of an electrode arrangement for a multi-pole.

[0029] Figure 13 is a schematic plan view of an electrode arrangement for another multi-pole.

[0030] Figure 14 is a schematic plan view of an electrode arrangement for another multi-pole.

[0031] Figure 15 is a schematic perspective view of an example electron-optical plate.

[0032] Figure 16 is Figure 12 another schematic plan view of the multipole shown.

[0033] Figure 17 is Figure 14 another schematic plan view of the multipole shown.

[0034] Figure 18 is a schematic plan view of an electrode arrangement for another multipole.

[0035] Figure 19 is a schematic plan view of an electrode arrangement for another multipole. DETAILED DESCRIPTION

[0036] Reference will now be made in detail to the example embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings in which the same numbers represent the same or similar elements between the several drawings. The implementation set forth in the description of the following example embodiments is not meant to be an all-inclusive explanation of all implementations consistent with the present disclosure. Rather, it is a description of example implementations consistent with the present disclosure as described in the following claims.

[0037] The enhancement of computing power of 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 can be achieved by increasing the resolution to fabricate smaller structures. For example, a thumb-sized smartphone IC chip available in 2019 or earlier can include over 2 billion transistors, each smaller than 1 / 1000th of a human hair. It is not surprising, therefore, that semiconductor IC fabrication is a complex and time-consuming process with hundreds of individual steps. Even an error in one step can have the potential to greatly affect the functionality of the final product. In some cases, even one defect can cause a device failure. The goal of the fabrication process is to improve the overall yield of the process. For example, to achieve a 75% yield in a 50-step process (where a step can indicate a layer 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%.

[0038] While high process yield is required for IC chip fabrication facilities, it is also important to maintain high substrate (i.e., wafer) throughput, defined as the number of substrates processed per hour. The presence of defects can affect both high process yield and high substrate throughput. This is especially true if operator intervention is required to inspect the defects. Therefore, high throughput detection and identification of micron and nanometer scale defects by detection systems such as scanning electron microscopes (SEMs) is critical to maintaining high yield and low cost.

[0039] SEM comprises a scanning device and an inspection device. The scanning device includes an illumination device, which comprises an electron source for generating primary electrons and a projection device for scanning a sample (such as a substrate) with one or more focused primary electron beams. At least the illumination device or system and the projection device or system together can be referred to as an electron optics device or column. Primary electrons interact with the sample and generate secondary electrons. The inspection device captures these secondary electrons from the sample as it is scanned, allowing the SEM to create an image of the scanned area of ​​the sample. For high-volume inspection, some inspection devices use multiple focused primary electron beams, i.e., multi-beams. The component beams of a multi-beam system can be called sub-beams or beam waves. Multi-beams can scan different portions of the sample simultaneously. Therefore, multi-beam inspection devices can inspect samples at much higher speeds than single-beam inspection devices.

[0040] The following describes the implementation of a known multi-beam inspection device.

[0041] These figures are schematic diagrams. 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 differences from individual embodiments are described only. Although the description and figures are directed to electro-optical devices, it should be understood that the embodiments are not intended to limit this disclosure to specific charged particles. Therefore, references to electrons in this document can be more generally considered as references to charged particles, where charged particles are not necessarily electrons. All references to charged particles can be considered to include at least electrons.

[0042] Now for reference Figure 1 This is a schematic diagram illustrating an exemplary charged particle beam inspection device 100, which may also be referred to as a charged particle beam evaluation system or simply an evaluation system. Figure 1 The charged particle beam inspection device 100 includes a main chamber 10, a loading and locking chamber 20, an electron beam device 40, an equipment front-end module (EFEM) 30, and a controller 50. The controller can be distributed among different components of the evaluation system, including, for example, in the electron beam device 40. The charged particle device 40 is located within the main chamber 10.

[0043] EFEM 30 includes a first loading port 30a and a second loading port 30b. EFEM 30 may include one or more additional loading ports. The first loading port 30a and the second loading port 30b may, for example, receive a front-opening substrate transfer cassette (FOUP) that holds a substrate (e.g., a semiconductor substrate or a substrate made of one or more other materials) or a sample to be inspected (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 a load-locking chamber 20.

[0044] The load lock chamber 20 is used to remove gas from around the sample. This creates a vacuum, i.e. a local gas pressure that is lower than the pressure in the surrounding environment. The load lock chamber 20 can be connected to a load lock vacuum pump system (not shown) that removes gas particles from the load lock chamber 20. Operation of the load lock vacuum pump system enables the load lock chamber to reach a first pressure that is lower than atmospheric pressure. After reaching the first pressure, one or more robot arms (not shown) transport the sample from the load lock chamber 20 to the main chamber 10. The main chamber 10 is connected to a main chamber vacuum pump system (not shown). The main chamber vacuum pump system removes gas particles from the main chamber 10 so that the pressure around the sample reaches a second pressure that is lower than the first pressure. After reaching the second pressure, the sample is delivered to an electron beam device through which the sample can be inspected. The charged particle device 40 can comprise a multi-beam electron optics device.

[0045] The controller 50 is, for example, signal-connected to the electron beam device 40, for example as a distributed component of the controller 50. The controller 50 can be a processor (e.g. a computer) configured to control the charged particle beam inspection apparatus 100. The controller 50 can also comprise processing circuitry configured to perform various signal and image processing functions. Although the controller 50 is shown in Figure 1 outside the structure comprising the main chamber 10, the load lock chamber 20 and the EFEM 30, it will be appreciated that the controller 50 can be part of this structure. The controller 50 can be located in one of the constituent elements of the charged particle beam inspection apparatus, or it can be distributed over at least two of these constituent elements. Although the present disclosure provides an example of a main chamber 10 that houses an electron beam inspection apparatus, it should be noted that aspects of the present disclosure are not limited to a chamber that houses an electron beam inspection apparatus in the broadest sense. Rather, it will be appreciated that the above principles can also be applied to other systems and other device arrangements that operate at a second pressure.

[0046] Reference is now made to Figure 2 , Figure 2 is a schematic diagram illustrating an example charged particle device 40. The charged particle device 40 can be provided as Figure 1FIG. 1 illustrates an example charged particle beam inspection system 100. The charged particle beam inspection system 100 includes a charged particle apparatus 40 and an evaluation apparatus 200. The charged particle apparatus 40 includes an electron source 201 and a charged particle column (or device) 230. The charged particle device 230 can refer to or include a projection apparatus for directing a primary charged particle beam 202 toward a sample 208. The electron source 201 and its associated and constituent charged particle optical elements can be referred to as an illumination apparatus for generating the primary charged particle beam 202. The evaluation apparatus includes a sample support for supporting the sample 208. The sample support in this example includes a sample holder 207. The sample holder 207 holds a sample 208 (e.g., a substrate or mask) for evaluation. The sample holder 207 is supported by a motorized or actuated stage 209. The charged particle apparatus 40 also includes a detector 240. The detector 240 detects signal charged particles (e.g., electrons) from the sample 208. The detector 240 generates a detection signal upon detecting the signal charged particles.

[0047] The electron source 201 can include a cathode (not shown) and an extractor or anode (not shown). During operation, the electron source 201 is configured to emit electrons as primary electrons from the cathode. The primary electrons are extracted or accelerated by the extractor and / or anode to form the primary electron beam 202.

[0048] The charged particle device 230 is configured to convert the primary electron beam 202 into a plurality of charged particle beams 211, 212, 213 and direct each beam onto the sample 208. While three beams are shown for simplicity, there can be tens, hundreds, thousands, tens of thousands, or even hundreds of thousands (or more) of beams. These beams can be referred to as beamlets or sub-beams. The plurality of charged particle beams can be collectively referred to as a multi-beam or beam grid. A beam grid with so many beams (e.g., more than a thousand beams) can have a field of view of, for example, more than 0.5 mm, such as in a range of 0.5 mm to 30 mm or 1 mm to 30 mm, such as in a range of 0.5 mm to 15 mm.

[0049] The controller 50 (e.g., a control system including distributed controllers) can be connected to Figure 1 various parts of the charged particle beam inspection apparatus 100, such as the electron source 201, the electron detection device 240, the charged particle device 230, and the actuated 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 inspection apparatus 100, including the operation of the charged particle apparatus 40.

[0050] The charged particle device 230 can be configured to focus, for example, the beams 211, 212, and 213 onto the sample 208 for inspection and can form three probe spots 221, 222, and 223 on the surface of the sample 208. The charged particle device 230 can be configured to deflect the primary beams 211, 212, and 213 to scan the probe spots 221, 222, and 223 over individual scan areas in a portion of the surface of the sample 208. In response to the primary beams 211, 212, and 213 being incident on the probe spots 221, 222, and 223 on the sample 208, electrons are generated from the sample 208, including secondary electrons and backscattered electrons, which can be referred to as signal charged particles. Secondary electrons typically have electron energies up to fifty electron volts (≤ 50 eV) and backscattered electrons typically have electron energies between fifty electron volts (50 eV) and the landing energy of the primary beams 211, 212, and 213.

[0051] The detector 240 can send detection signals generated in the detector 240 (e.g., as imaging or detection signals) to the controller 50 or a signal processing system (not shown, which can be part of the controller 50), for example, to construct images of corresponding scan areas of the sample 208. The detector 240 can be at least partially incorporated into the charged particle device 230 or can be separate therefrom, for example, in the case of a secondary optical column directing secondary electrons to the detector 240.

[0052] The controller 50 can include an image processing system including an image acquirer (not shown) and a storage device (not shown). For example, the controller can include a processor, a computer, a server, a mainframe, a terminal, a personal computer, any type of mobile computing device, etc., or combinations thereof. The image acquirer can include at least a portion of the processing functionality of the controller. Thus, the image acquirer can include at least one or more processors. The image acquirer can be communicatively coupled to the detector 240 to allow signal communication, such as electrical conductors, fiber optic cables, portable storage media, IR, Bluetooth, the Internet, wireless networks, radio, etc., or combinations thereof. The image acquirer can receive detection signals from the detector 240, can process data included in the signals, and can construct images therefrom. Thus, the image acquirer can acquire images of the sample 208. The image acquirer can also perform various post-processing functions, such as generating contours, superimposing indicators on acquired images, and so forth. The image acquirer can be configured to perform adjustments in brightness and contrast, etc., of acquired images. The storage device can be a storage medium such as a hard disk, a flash drive, a cloud storage device, a random access memory (RAM), other types of computer readable memory, etc. The storage device can be coupled with the image acquirer and can be used to save raw image data of scans as raw images and post-processed images.

[0053] The image acquirer can acquire one or more images of the sample 208 based on the imaging signals received from the detector 240. The imaging signals can correspond to a scanning operation for charged particle imaging. The acquired image can be a single image comprising a plurality of imaging regions. The single image can be stored in a storage device. The single image can be a raw image that can be divided into a plurality of regions. Each region can comprise an imaging region containing a feature of the sample 208. The acquired image can comprise a plurality of images of a single imaging region of the sample 208 sampled a plurality of times over a period of time. The plurality of images can be stored in a storage device. The controller 50 can be configured to perform image processing steps on the plurality of images of the same location of the sample 208.

[0054] The controller 50 can comprise measurement circuitry (e.g. an analogue to digital converter) for acquiring a distribution of detected secondary electrons. A portion of the controller for such functionality can be included in or near the detector. The electron distribution data collected during a detection time window can be used in conjunction with corresponding scan path data for each of the primary beams 211, 212 and 213 incident on the sample surface to reconstruct an image of the sample structure under examination. The reconstructed image can be used to reveal various features of the internal or external structure of the sample 208. Thus, the reconstructed image can be used to reveal any defects that can be present in and / or on the sample.

[0055] The controller 50 can control the actuated stage 209 to move the sample 208 during the sample 208 examination, for example to provide a scanning motion of the stage relative to the path of the primary beam. The controller 50 can enable the actuated stage 209 to move the sample 208 at least in a portion of the scan motion of the stage, preferably continuously, at a constant speed during the sample examination. The controller 50 can control the movement of the actuated stage 209 such that it varies the speed of movement of the sample 208 according to various parameters. For example, the controller can control the stage speed (including its direction) according to the examination steps of the scanning process and / or characteristics of the scan, for example as disclosed in EPA 2117 1877.0, filed on 3 May 2021, which is incorporated herein by reference in relation to at least the combined stepping and scanning strategy of the stage. In controlling the actuated stage, the actuation of the stage and the actuation of the sample can enable the sample to be dynamically positioned relative to the path of the primary beam.

[0056] Figure 3is a schematic diagram of an exemplary electron-optical device 41 (which can also be referred to as a charged-particle device) for use in evaluating apparatus. For ease of illustration, a lens array is schematically depicted here with an array of ovals. Each oval represents a lens in the lens array. The shape of the ovals is used by convention to represent a lens, similar to the biconvex shape often employed in optical lenses. In the context of electron-optical devices such as those discussed herein, it will be understood that the lens array will typically be operated electrostatically, and thus can not require any physical element to employ the biconvex shape. As described below, the lens array can instead comprise a plurality of apertured plates. Each apertured plate can be referred to as an electrode. The electrodes can be arranged in series along the path of a beamlet grid of a plurality of charged-particle beams (which can also be referred to as beamlets). The electrodes are thus also in series along the path of the charged-particle beams of the beamlet grid.

[0057] An electron source 201 directs electrons toward an array of condenser lenses 231 forming part of a charged-particle device 230. The electron source 201 is desirably a high-brightness thermal field emitter with good trade-off between brightness and total emission current. There can be tens, hundreds, or thousands, or even tens of thousands of condenser lenses 231. The condenser lenses of the array 231 can comprise multi-electrode lenses and have a construction based on EP1602121A1, which is specifically incorporated herein by reference to disclose a lens array that splits an electron beam into a plurality of beamlets, the array providing a lens for each beamlet. The array of condenser lenses can take the form of at least two, preferably three, plates that act as electrodes, the apertures in each plate being aligned with the apertures in the other plates to define the path of the charged-particle beams through the plates. During operation, at least two of the plates are held at different potentials to achieve the desired lens effect. Between the plates of the array of condenser lenses are electrically insulating plates, for example made of an insulating material such as ceramic or glass, having one or more apertures for the charged-particle beams. Additionally or alternatively, one or more of the plates can have apertures each with its own electrode, for example an array of electrodes at its periphery, or arranged as groups of apertures with a common electrode. In a variant, one or more of the plates can comprise a plurality of sections or strips having a plurality of apertures. In another alternative arrangement, a macro-collimator is provided in place of the array of condenser lenses. The macro-collimator can act on the beam from the source 201 before the beam is split into multiple beams. The macro-collimator can be implemented magnetically, electrostatically, or magnetically and electrostatically.

[0058] In some embodiments, the array of condenser lenses is formed of three arrays of plates, in which the charged particles have the same energy as they enter and exit each lens, which arrangement can be referred to as a single-lens. Thus, chromatic dispersion occurs only within the single lens itself (between the entrance and exit electrodes of the lens), limiting off-axis chromatic aberrations. When the thickness of the condenser lenses is small (e.g., a few millimeters), the effect of this aberration is small or negligible.

[0059] Each condenser lens in the array directs electrons into a corresponding beam 211, 212, 213, which is then focused at a corresponding intermediate focal point 233. A collimator or collimator array can be positioned to operate on the corresponding intermediate focal point 233. The collimator can take the form of a deflector 235 positioned at the intermediate focal point 233. The deflector 235 is configured to bend the corresponding beams 211, 212, 213 by a certain amount to ensure that the principal ray (which may also be referred to as the beam axis) is incident substantially perpendicularly onto the sample 208 (i.e., substantially at 90° to the nominal surface of the sample). Note that in an arrangement with macro-condenser lenses, the condenser lenses can collimate or contribute to collimating the source beam, or in one embodiment, collimate multiple beams.

[0060] Objective array 401 is positioned downstream of the beam of deflector 235. Objective array 501 includes objectives for each beam 211, 212, 213. Objective array 401 projects beams 211, 212, 213 onto sample 208. Objective array 401 may include two or more, preferably at least three, plate electrode arrays connected to respective potential sources.

[0061] Optionally, a control lens array 250 is disposed between the deflector 235 and the objective lens array 401. The control lens array 250 includes control lenses for each of the beams 211, 212, 213. The control lens array 250 provides additional degrees of freedom for controlling the characteristics of the beams 211, 212, 213. The control lens array 250 may include two or more, preferably at least three, plate electrode arrays connected to respective potential sources. The function of the control lens array 250 is to optimize the beam aperture angle relative to beam reduction and / or control the beam energy delivered to the objectives, each objective guiding the corresponding beam 211, 212, 213 onto the sample 208. In one embodiment, the control lens array may be considered part of the objective, such as an additional plate associated with the objective lens array.

[0062] Optionally, an array of scanning deflectors 260 is disposed between the control lens array 250 and the objective lens array 401. The array of scanning deflectors 260 includes a scanning deflector for each beam 211, 212, 213. Each scanning deflector is configured to deflect the corresponding beam 211, 212, 213 in one or both directions, so that the beam scans across the sample 208 in one or both directions. Alternatively, a macro-scanning deflector may be provided to scan the beam of charged particles on the sample 208. The macro-scanning deflector may be disposed upstream of the beam in the control lens array 250. In one embodiment, such a macro-scanning deflector can operate on the source beam and may coexist with a macro-condenser lens.

[0063] A detector module 402 of the detector is disposed within or between the objective and the sample 208 to detect signal electrons / particles from the sample 208. Exemplary structures of such detector modules 402 are described below. Note that the detector can additionally or alternatively have detector elements up the main beam path along the objective array 401 or even the control lens array 250. The detector module can be an array of detector elements (e.g., a detector array). Each element can be associated with an individual beam, e.g., positioned to detect signal particles produced by the individual beam. The detector module can include at least one of a scintillator element, a semiconductor element, or a charge-capturing electrode, e.g., to capture signal electrons as an electrical current.

[0064] Figure 3 The charged particle device 41 can be configured to control the landing energy of the electrons on the sample 208 by varying the electric potentials applied to the electrodes of the control lens and the objective. The control lens and the objective work together and can be referred to as an objective assembly. Depending on the properties of the sample being evaluated, the landing energy can be selected to increase the emission and detection of secondary electrons. A detector module can be included in the objective assembly.

[0065] The objective can be configured to reduce the electron beam by a factor of ten or less, desirably in the range of 100 to 50 or less. The objective can include three electrodes: a middle electrode, a lower electrode, and an upper electrode. The upper electrode can be 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 thereby enable a stronger lens. Additional electrodes (i.e., more than two electrodes) provide additional degrees of freedom for controlling the electron trajectory, e.g., focusing secondary electrons and the incident beam.

[0066] In some embodiments, the objective lens array assembly comprises a detector having a detector module 402 under the beam of at least one electrode of the objective lens array 401. The detector module 402 can comprise or even take 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 lens array 401. For example, the detector module 402 can be implemented by integrating a CMOS chip detector into the bottom electrode of the objective lens array 401. Integrating the detector module 402 into the objective lens array can replace the second column. The CMOS chip is preferably oriented to face the sample (as the distance between the sample and the bottom of the electron optical system is small, which can for example be in the range of 10 to 400 micrometers, desirably in the range of 50 to 200 micrometers, optionally about 100 micrometers). It should be noted that even in the case that the detector is upstream of the most downstream electron optical element of the charged particle device, there can be a close, e.g. similar distance spacing (e.g. about 100 micrometers) between the most downstream electron optical element and the sample. In one embodiment, electrodes for capturing the signal charged particles are formed in the top metal layer of the CMOS device. The electrodes can be formed in other layers of the substrate, e.g. in other layers of the CMOS chip. The power and control signals of the CMOS can be connected to the CMOS through through-silicon vias. For robustness, the bottom electrode is preferably composed of two elements: a CMOS chip and a passive Si plate with holes. This plate shields the CMOS from high electric fields.

[0067] In one embodiment, a single electrode surrounds at least some of the apertures. In one arrangement, a single electrode is allocated around each aperture, for example. In another embodiment, a plurality of electrode elements are provided around each aperture, e.g. as detector elements. Signal charged particles captured by electrode elements surrounding one aperture can be combined into a single detection signal or used to generate independent detection signals. The electrode elements can be separated radially (i.e. to form a plurality of concentric rings), angularly (i.e. to form a plurality of sectors), radially and angularly (to provide a dartboard-like arrangement), or in a grid (e.g. a checkerboard), or in any other convenient manner.

[0068] In Figure 4 an exemplary embodiment of a detector integrated into the objective lens array 401 is shown, Figure 4 a portion of the objective lens array 401 is shown in a schematic cross-sectional view. In this embodiment, the detector comprises a detector module 402 comprising a plurality of detector elements 405 (e.g. an array), as Figure 5The illustrated (e.g. sensor elements such as capture electrodes) are preferably as an array of detector elements (i.e. a plurality of detector elements, preferably in a pattern or arrangement on 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 array 401. Figure 5 is a bottom view of the detector module 402, which comprises a substrate 404 on which a plurality of detector elements (or capture electrodes 405) are provided, each detector element surrounding a beam aperture 406. The beam apertures 406 can be formed by etching through the substrate 404. In Figure 5 In the illustrated arrangement, the beam apertures 406 are shown in a rectangular array. The beam apertures 406 can also be arranged differently, for example as Figure 6 a hexagonal close-packed array as illustrated.

[0069] The above integrated detector module 402 is particularly advantageous when used with an evaluation device having an adjustable landing energy (e.g. comprising electron optics), as the secondary electron capture can be optimized for a range of landing energies. The detector module with an array or array form can also be integrated into other electrode arrays, not only the lowest electrode array. Further details and alternative arrangements of the detector module integrated into the objective can be found in EP application no. 20184160.8, which is incorporated herein by reference.

[0070] A power supply can be provided to apply respective electric potentials to the electrodes of, for example, the control lenses of the control lens array 250 and the objective lenses of the objective array 401 and condenser lenses of the condenser lens array or any electron optical elements or components of the electron optics 41 (e.g. when integrated into the objective array or when the objective and detector module are separate components). The controller 50 can control the electric potentials applied to the electron optical components of the electrodes such as the condenser lens array, the objective array and / or the control lens array.

[0071] The electron optics 41 can comprise further electron optical components, for example charged particle correctors, for example as a corrector array, for aligning the source to the sample and between the beams of the multi-beam and for adjusting the focus of the different beamlet groups or individual beams of the beamlet grid. Such correctors can be controlled to operate dynamically and / or statically, for example during a boost of the electron optics device 41, a service or a calibration.

[0072] In one embodiment, an array of electron-optical devices (or device array) is provided. The array can include a plurality of any of the electron-optical devices described herein (e.g., electron-optical columns or charged-particle devices). Each electron-optical device in the array focuses a respective plurality of charged-particle beams onto different regions of the same specimen 208. Each electron-optical device in the array can derive the respective plurality of charged-particle beams from different respective sources 201. Each respective source 201 can be one of a plurality of sources 201. At least a subset of the plurality of sources 201 can be provided as a source array. The source array can include a plurality of emitters on a common substrate. Simultaneously focusing a plurality of charged-particle beams from different electron-optical devices onto different regions of the same specimen allows for increased area of the specimen 208 to be simultaneously exposed to charged-particle beams. Thus, an increased area of the specimen can be processed (e.g., evaluated) at one time. The electron-optical devices in the device array can be arranged adjacent to one another so as to project the respective plurality of beams onto adjacent regions of the specimen 208. Any number of electron-optical devices can be used in the array. Preferably, the number of electron-optical devices is in the range of 9 to 200. Each electron-optical device in the device array can be configured in any of the ways described herein when referring to a single electron-optical device, charged-particle device or system or column. Alternatively or additionally, one or more of the electron-optical devices in the array can be configured to project a single beam.

[0073] Figure 7 Another example of an electron-optical device 41 is schematically depicted. Features that are the same as described above are denoted with the same reference numerals. For brevity, the features are not described in detail Figure 7 The features are described in detail. For example, the source 201, condenser lens 231, objective array 401, and specimen 208 (e.g., on the specimen support 207) can be as described above. In this example, a macro-collimator 270 is provided, rather than a deflector array of the type described above with reference to Figure 3 The macro-collimator can be a magnetic, electrostatic, or both, macro-lens. In other embodiments, a deflector array can be used to at least assist in the collimation of the beams, so the deflector array is used for deflection for finer collimation than the action of the macro-collimator 270. Such an arrangement can also include an array of multiple deflectors (e.g., with multiple electrodes per aperture) for finer collimation. In one configuration, the condenser lens 231 can include a single plate defining an array of beam-limit apertures, with multiple apertures defined in the array of beam-limit apertures, with one or more associated macro-electrodes having a single aperture. Such an array of beam-limit apertures and associated macro-electrodes can also form a condenser lens array to focus the generated beams at an intermediate focus, which desirably corresponds to the location of the collimator 270.

[0074] As described above, in some embodiments, a detector can be provided between the objective lens array 401 and the sample 208. The detector can face the sample 208. Alternatively, as shown in Figure 7 the detector 240 can be implemented such that the objective lens array 401 is located between the detector 240 and the sample 208.

[0075] In one embodiment, a deflector array 95 is provided between the detector 240 and the objective lens array 401. In one embodiment, the deflector array 95 comprises a Wien filter array, such that the deflector array 95 can be referred to as a beam separator. The deflector array 95 is configured to provide a magnetic field and an electrostatic field. The electrostatic and magnetic fields operate together to separate charged particles projected at the sample 208 with respect to signal particles (e.g. electrons from the sample 208). The operation of the fields directs the signal particles towards the detector 240.

[0076] In one embodiment, the detector 240 is configured to detect the signal particles by reference to the energy of the charged particles (i.e. dependent on the bandgap), for example a detector based on a semiconductor type. Such a detector 240 can be referred to as an indirect current detector. The secondary electrons emitted from the sample 208 gain energy from the field between the electrodes. The secondary electrons have sufficient energy once they reach the detector 240. In different arrangements, the detector 240 can be an electron photon converter, for example a scintillator array, for example a fluorescent band between the beams, upstream of the Wien filter along the primary beam path. The primary beams through the Wien filter array (with magnetic and electrostatic bands orthogonal to the primary beam path) have a path upstream and downstream of the Wien filter array that is substantially parallel, while the signal electrons from the sample are directed by the Wien filter array towards the scintillator array. The electron photon converter can be photonically coupled to a photon electron converter to convert any photons generated in and emitted by the electron photon converter. The photon electron converter can be electrically connected to an electronic circuit to process the detection signal. In different embodiments, the photon electron converter can be within or outside of the charged particle device. In one embodiment, the photon coupling can be coupled to a remote optical detector by a photon transport unit (e.g. an optical fibre array) that generates a detection signal when a photon is detected.

[0077] Figure 8 is a schematic diagram of a further exemplary electron optical device 41 for use in an evaluation apparatus. The electron optical device 41 can be used in conjunction with any of the embodiments described herein, for example in place of any of the electron optical devices 41 described above (e.g. with reference to Figure 3 and / or Figure 7). In this example, the electron optics 41 comprises an electron source 201, a beam forming aperture array 502, a condenser lens 504, a source conversion unit 506, an objective lens 508, and a sample 208. The source 201 and the sample 208 can take any form described, for example, with reference to Figure 2 , Figure 3 and Figure 7 . The source 201, the beam forming aperture array 502, the condenser lens 504, the source conversion unit 506, and the objective lens 508 can be aligned with a primary electron optical axis 510 of the charged particle device 41. The source 201 generates a primary electron beam 512 having a source crossover 514. The beam forming aperture array 502 forms beams 521, 522, 523 from the primary beam 512. A line of three beams is shown, but the beam forming aperture array 502 can be configured to form a line of two beams or a line of more than three beams, for example a line of four beams or a line of five beams. The beam forming aperture array 502 can also be configured to form multiple lines of beams, thereby forming a beam array. For example, the beam forming aperture array 502 can be configured to form an n x m beam array, where n and m are integers that can be the same or different, for example a 3 x 3 beam array, a 4 x 4 beam array, or a 5 x 5 beam array.

[0078] The condenser lens 504 can be configured to redirect the paths of the beams 521, 522, 523 to be substantially parallel to each other and / or to be substantially perpendicular to impinge on the source conversion unit 506. The condenser lens 504 can be a macro-magnetic lens device, for example a plurality of (e.g. two) lenses arranged in a non-rotating arrangement (the rotational effects of different lenses of the lens device are cancelled out by them, or their net rotational effect on the beam path is substantially zero).

[0079] The source conversion unit 506 can comprise a beam limiting aperture array 531 defining apertures configured to laterally limit each of the beams 521, 522, 523. The beam limiting aperture array 531 can for example shape one or more of the beams 521, 522, 523 to split the beam into two or more beams downstream of the beam limiting aperture array 531, for example towards the sample.

[0080] The source conversion unit 506 can comprise an array of electron optical components for operating on each of the beams or groups of beams. The source conversion unit 506 can comprise an imaging element array 532 comprising a micro-deflector array configured to deflect the beams 521, 522, 523 towards the axis 510. Deflecting the beams 521, 522, 523 can form a virtual image of the source crossover 514 on the sample 208.

[0081] The source conversion unit 506 can comprise an array of aberration compensators 534 configured to compensate for aberrations in the beams 521, 522, 523. The array of aberration compensators 534 can be configured to, for example, compensate for field curvature and / or astigmatism.

[0082] The source conversion unit 506 can comprise an array of pre-bend micro- deflectors 533 configured to bend the paths of the beams 521, 522, 523 upwards along the beam limiting aperture array 531, for example to cause the paths of the beams 521, 522, 523 to be incident substantially perpendicularly onto the beam limiting aperture array 531.

[0083] The array of imaging elements 532, the array of aberration compensators 534 and / or the array of pre-bend micro-deflectors 533 can comprise a plurality of layers of beamlet steering devices, some of which can be in the form of an array, for example: micro-deflectors, micro-lenses and / or micro-astigmators.

[0084] In the example shown, the objective 508 comprises a magnetic lens which acts macroscopically on the beams to focus the beams onto the sample 208. In other embodiments, the objective 508 can comprise an electrostatically implemented objective array, or a combination of magnetic and electrostatic lenses can be used; for example, a macro-magnetic objective with electrostatic elements.

[0085] Figure 9 An electron-optical module 55 is shown. The electron-optical module 55 can comprise an electron-optical stack. The electron-optical stack comprises a plurality of electron-optical plates 60. The electron-optical stack can form part of any of the electron-optical devices 41 disclosed herein, for example the electron-optical devices 41 described with reference to Figure 3 , Figure 7 and Figure 8 The electron-optical stack can be provided as part of an evaluation apparatus for evaluating a sample. The electron-optical stack can be or form part of an electron-optical lens assembly. The electron-optical lens assembly can comprise or be an objective array or assembly, or a condenser array or assembly. Additionally or alternatively, the electron-optical stack can be or form part of one or more elements of, for example, a respective array, a collimator, a corrector (e.g. an individual beam corrector), a detector array, a deflector and / or a Wien filter array. For example, in the embodiments shown and described with reference to Figure 3 The stack 55 can comprise the detector module 402, the objective array 401 and the control lens array 250. In the embodiments shown and described with reference to Figure 8 The stack can comprise at least part of the source conversion module 506. That is, the electron-optical module 55 can comprise or even be the source conversion module 506

[0086] Electron optics module 55 is configured to guide charged particles toward the sample location along at least one beam path. Figure 9 In the illustrated orientation, at least one beam path extends vertically from top to bottom through the middle of the electron-optical stack. There may be one beam path corresponding to a single charged particle beam. Alternatively, there may be multiple beam paths corresponding to multiple charged particle beams in a plurality of beams.

[0087] like Figure 9 As shown, in one embodiment, the electron optics module 55 includes a plurality of planar elements arranged across the beam path. In one embodiment, one or more planar elements are electron optics plates 60 (which may also be referred to as electron optics elements). Electron optics plates 60 are configured to operate on one or more electron beams. Figure 9 As shown, in one embodiment, all planar elements are electro-optical plates 60. Alternatively, one or more planar elements may be planar elements different from electro-optical plates. For example, one or more of the planar elements may be elements that do not require a voltage to perform their function, or planar elements that require a voltage to be applied such that there is a substantially zero potential difference between the element and adjacent elements along the beam path. One example is a planar element as a beam-confining aperture array comprising apertures sized to shape a beam of charged particles. For example, the apertures may allow a specific shape of charged particle beam to pass through while preventing other charged particles from propagating through the beam-confining aperture array. As another alternative, planar elements configured to shape a charged particle beam may also have a potential difference relative to upstream and / or downstream planar elements, such that, in addition to beam-shaping, an electromagnetic field also affects the charged particle beam. In one embodiment, one or more planar elements may be detectors, such as a detector array.

[0088] like Figure 9 As shown, in one embodiment, the electro-optics module 55 includes one or more spacers 70. The spacers 70 are configured to mechanically support planar elements. Figure 9 As shown, in one embodiment, spacer 70 is configured to mechanically separate planar elements, such as electron optical plates 60, from each other. In one embodiment, spacer 70 is configured to electrically insulate planar elements, such as electron optical plates 60, from each other. However, providing electrical insulation with spacer 70 is not necessary. For example, two adjacent electron optical plates 60 can be arranged to operate at the same voltage (i.e., without a potential difference between them), in which case electrical insulation may not be required. In one embodiment, one or more pairs of adjacent planar elements are directly joined to each other, i.e., without intermediate spacer 70. Spacer 70 is an optional feature.

[0089] In one embodiment, the electro-optical module 55 is configured such that a beam of charged particles passes through a beam region 62 of the electro-optical module 55. For example... Figure 9 As shown, the beam region 62 can be located in the central portion of the electro-optics module 55. The beam region 62 is typically located at the center when viewed in a direction parallel to at least one beam path. The beam region 62 is also located at the center when viewed in a direction orthogonal to the plane of the planar element. It should be noted that in one embodiment, one or more plates 60 can be a single macro aperture. Such a macro aperture can be positioned to correspond to the beam area of ​​the other plates in the plate 60. Such a stack with a macro aperture can be or include, for example... Figure 3 and Figure 7 The condenser lens array 231 shown and described. In one arrangement, one or more plates 60 may include multiple apertures (or mesoapertures) corresponding to beam path groups in the beam region. A stack including one or more plates with mesoapertures may include a Wien filter array 95.

[0090] In one embodiment, the electro-optical module 55 is included in the electro-optical device 41, for example... Figure 3 , Figure 7 or Figure 8 The electro-optical device 41 is shown. In one embodiment, the electro-optical module 55 is field-replaceable. The electro-optical module 55 can be removed from and / or inserted into the electro-optical device 41 without any substantial disassembly of other components of the electro-optical device 41. That is, the electro-optical module 55 can be removed from and / or inserted into the electro-optical device 41.

[0091] As mentioned above, electron optical elements such as the plate 60 can be configured to act as electrodes, for example as part of an objective lens array. The geometry of the plate 60 allows charged particle beams to pass through the plate 60. These features are: channels through the plate 60 and apertures defined in the plate surface. The apertures can be defined by corresponding channel openings in the surface. Channels (which can be referred to as vias) can connect different apertures in opposite surfaces of the plate. An electric field adjacent to an aperture associated with a channel can exert a lensing effect on charged particles. In some arrangements, the apertures can be adapted to compensate for aberrations, for example off-axis aberrations in a multi-beam, such as distortion, curvature of focus, astigmatism and coma. For example, the shape, size and / or position of the apertures of one or more electrodes can compensate for off-axis aberrations. For example, the apertures can have a range of different areas (or a range of diameters) to compensate for curvature of field, a range of different ellipticities to compensate for astigmatism, and / or a range of different displacements from a nominal grid position to compensate for distortion caused by telecentric error. See, for example, EPA 21166214.3, filed 31 March 2021, incorporated herein by reference as a reference for off-axis aberration correction.

[0092] The performance of an electron optical element can be highly sensitive to variations in properties of an aperture, such as its shape, size and / or position, particularly where these features are intentionally configured to correct for aberrations.

[0093] Features in an electron optical plate 60 can be manufactured using technology from micro-electromechanical systems (MEMS), i.e. using MEMS fabrication techniques. Errors in the manufacturing process of an electron optical plate 60 can affect the electron optical performance of the plate. Such errors can be unwanted structural features created during processing steps of the manufacturing. Small perturbations to the nominal shape of an aperture can cause significant aberrations in a charged particle beam passing through the aperture. The effect of the perturbation can be amplified by the strong curved fields in the vicinity of the aperture. Such perturbations can be two orders of magnitude larger than the compensations intentionally applied to the aperture, for example to compensate for off-axis aberrations. However, it is expected that such perturbations can typically be smaller than the order of the compensations applied to the aperture.

[0094] Figure 10 An exemplary electron optical stack 64 configured to manipulate a plurality of charged particle beams is shown. The stack 64 comprises a plurality of electron optical plates 60. As mentioned above with reference to Figure 9 The stack 64 can be part of an electron optical module 55. The stack 64 and / or the module 55 can take any of the forms described above with reference to Figure 9 The plurality of plates 60 can thus be configured to allow at least adjacent plates 60 to be maintained at different electric potentials, for example to provide lensing effects. Accordingly, adjacent plates can be electrically isolated from one another. In some embodiments, spacers 70 are provided between adjacent plates. The spacers 70 can electrically isolate adjacent plates 60 and / or support adjacent plates 60.

[0095] like Figure 10 As shown, multiple plates 60 have main surfaces 82A, 82B on opposite sides of the plates 60. Therefore, each plate 60 has two main surfaces 82A, 82B. The main surfaces 82A, 82B are the largest surfaces of the plate 60. The main surfaces 82A, 82B are typically planar surfaces and / or have a much larger surface area than other surfaces of the plate 60 (e.g., the side surfaces of the plate). Figure 10 In the orientation of the stack 64 shown, each plate 60 has a main surface at the top of the plate 60 and a main surface at the bottom of the plate 60.

[0096] Plate 60 defines one or more sets of channels 84, for example, between its main surfaces. Thus, apertures in the main surfaces of the plate can define corresponding channels through the plate. As shown, each set of channels 84 is configured to align along the beam path of a corresponding charged particle beam. In the described arrangement, the channels in this set and the corresponding beam path are substantially orthogonal to the planes of the different plates 60 (although the beam does not need to be aligned with different channels). The alignment of the channels 84 in each set allows the charged particle beam to pass through the plate 60 via the channels 84 of that set. In embodiments configured to operate with a single charged particle beam, a single set of channels 84 may be provided. In embodiments configured to operate with multiple charged particle beams (which may be referred to as beam grids), multiple plates 60 can define multiple sets of channels 84 (or channel arrays or channel grids) for corresponding multiple paths of different charged particle beams (e.g., beam grids). Each set of channels 84 corresponds to a corresponding charged particle beam. As shown in the figure, the beam paths of the beam grid are collimated, and virtually all beam paths are perpendicular to the plane of the plate, such as one of its main surfaces, and the beam paths are parallel to the axis of the corresponding channel.

[0097] For example, each channel 84 defines apertures 86A and 86B in the two main surfaces 82A and 82B of the plate 60 defining the channel 84. Therefore, in Figure 10 In this example, six apertures are defined along each beam path through plate 60. Two apertures 82A and 82B are associated with each channel 84. When a potential is applied between adjacent plates, for example, when a potential is applied around facing apertures in at least different adjacent plates, a field is generated between the facing apertures. This field can manipulate charged particles in the beam along the beam path to, for example, lens the beam. In one embodiment, multiple plates 60 are configured to function as a single lens.

[0098] Figure 11 This is a schematic diagram showing a cross-sectional view of the electron optical plate 60 near the channel 84 passing through the plate 60. (See diagram below.) Figure 11As shown, in one embodiment, board 60 includes a CMOS device. Board 60 can be implemented by integrating a CMOS chip corrector into board 60 (which may be a lens board or a separate element) of an electro-optical lens array. The CMOS chip has a structure comprising multiple conductive layers, with isolation layers between the conductive layers. The conductive layers can be interconnected with each other using silicon vias through an insulating material. Note that the CMOS device provides embodiments for circuitry used to connect and control different electrodes.

[0099] In one embodiment, a plurality of electrodes 76 are arranged around the aperture of channel 84. Channel 84 may define a through path through plate 60. Channel 84 may define the path of an electron beam. Circumferential gaps may be defined between adjacent electrodes 76. Such circumferential gaps between adjacent electrodes may isolate adjacent electrodes. Circumferential gaps and electrodes may lack rotational symmetry, for example, they may not have rotational symmetry, but may have reflection symmetry. Reflection symmetry may be the position of segments relative to the geometric axis of channel 84. Electrodes 76 are configured to perform correction through multipole of any order, such as two-pole (2 poles), four-pole (4 poles), six-pole or six-pole (6 poles), eight-pole or eight-pole (8 poles), ten-pole (10 poles), twelve-pole (12 poles), fourteen-pole (14 poles), sixteen-pole (16 poles), or any other higher-order multipole. Two poles may have single-order reflection symmetry. Four poles may have second-order reflection symmetry. Six poles may have triple reflection symmetry. An octet can have quadruple reflection symmetry. A dodecet can have hexaple reflection symmetry. Such a multipole electrode can be considered a corrector. Electrode 76 can be configured to perform operations, such as correction, on the beam passing through the channel path. Correction can adjust, for example, one or more properties of one or more aberrations (e.g., off-axis aberrations), such as astigmatism and position (i.e., inter-beam alignment or intra-beam array alignment).

[0100] In one embodiment, electrode 76 has a metal surface, such as a layered metal surface layer, which can be, for example, a CMOS device (which may be referred to as a CMOS chip). Electrode 76 may be formed in other (i.e., additional) layers of the device. The power and control signals of the device can be connected to the device via, for example, through a through-silicon via 78 from an adjacent conductive structure such as an adjacent substrate. For robustness, it is desirable for a passive silicon substrate with holes (e.g., a shielding plate 73) to shield the device from high electric fields. Figure 11 (Not shown in the image). The device does not have to be a CMOS device. The device does not have to be multilayered. For example, in an alternative embodiment, the device comprises a single-layer trace on a substrate.

[0101] like Figure 11As shown, the beam channel 84 is defined by the electrodes 76 that surround the channel 84. On the surface of the planar substrate of the plate 60, a circuit 74, such as an electronic control circuit, is arranged for connecting and controlling the electrodes 76. In one embodiment, the circuit 74 comprises an integrated circuit that is arranged adjacent to, for example surrounding, the channel 84 within the layers 75 of the device. In this example, the circuit 74 is composed of a plurality of layers 75 with integrated electronic circuitry. The circuit 74 can be on one or more layers of the device. The layers 75 are interconnected by vias 78. In one embodiment, the plate 60 comprises at least a portion of the circuit 74. In one embodiment, the inner surface of the plate 60 extends from the portion of the electrodes 76 that is perpendicular to the beam path to the opposite face of the substrate of the plate 60, desirably through the plate 60. The electrodes 76 can extend through the plate 60 along a portion or even the entire surface of the channel 84.

[0102] In one embodiment, the circuit associated with the detector elements within the corrector plate can comprise at least a portion of the control circuit of the controller 50, for example a portion of the controller associated with the detector elements. Components of the controller circuit in the circuit layer can include deserializers, digital-to-analog converters, and amplifiers. In one embodiment, at least a portion of the control circuit is remote from the corrector plate, desirably remote from the electron optics device, for example outside of a vacuum chamber in which the electron optics device is located.

[0103] In one embodiment, an edge via 77 is provided at the edge or surface of the channel 84. In one embodiment, the edge via 77 is connected to the electrode 76. In one embodiment, the edge via 77 is integrally formed as part of the electrode 76; that is, the electrode 76 can comprise the edge via 77. The edge via 77 provides an extension of the electrode 76 within the channel 84 or provides a surface that passes through the plate 60. Thus, the electrode 76 of the channel 84 is arranged at least partially against the inwardly facing wall of the channel 84. The electrode is at least partially provided at a surface within and on the substrate. The edge via 77 can be fabricated simultaneously and using the same processes used to fabricate the integrated electronic control circuit 74, for example using CMOS structures and using processes for processing CMOS structures.

[0104] In one embodiment, each of the channels 84 is provided with a plurality of electrodes 76 arranged around the beam channel 84 on the substrate of the plate 60. At a distance above the substrate of the plate 60, other plates (not shown in Figure 11 ) can be arranged. The other plates can also comprise an array of channels 84 that are aligned with the channels 84 of the plate 60. In one embodiment, such other plates and the plate 60 can correspond to the arrangement of two of the plates 60 shown in Figure 10 and described with reference to Figure 10 .

[0105] As Figure 11As shown, in one embodiment, the electrodes 76 extend farther along the wall (or surface) of the beam passage 84 (or passage through the plate 60) than the layer 75 of the circuit 74 (optionally). Alternatively, the electrodes 76 can extend along the wall of the beam passage 84 substantially the same distance (or a shorter distance) as the layer 75 of the circuit 74. In one arrangement, the electrodes can extend to a position between the farthest extent of the layer 75 and the aperture of the passage 84 at the opposite end of the passage 84. In one arrangement, the electrodes can extend all the way through the passage 84, i.e., to the opposite end of the passage 84. As Figure 11 As shown, in one embodiment, the uncovered portion 66 of the wall defining the beam passage 84 (or surface of the beam passage 84) is uncovered; that is, the beam passage 84 does not provide a surface of the electrode 76 that is, for example, covered by the electrode 76. In one embodiment, the uncovered portion 66 can be recessed relative to the surface of the electrode 76 on the inner surface of the substrate. That is, the passage through the inner surface of the substrate can step to a larger diameter where the electrode 76, for example, terminates within the plate 60. Such a stepped surface can desirably reduce the risk of unwanted electrical discharges.

[0106] In one embodiment, the electrodes 76 can be formed as a layer such as a coating at the surface of the substrate. In an alternative embodiment, the electrodes 76 are made from a doped portion of the substrate of the plate 60; the doped portion can be formed to provide the layer of the electrode. For example, the electrodes 76 can be formed from doped silicon.

[0107] In one embodiment, the controller 50 is configured to control the electrodes 76 through a serial bus. In one embodiment, the device is programmed through the serial bus. This helps to reduce the number of electrical connections needed to control the electrodes 76. It is desirable that embodiments of the present invention make it easier and / or cheaper to manufacture electronic optical devices with strong aberration correctors.

[0108] In one embodiment, the plate 60 includes a digital-to-analog converter. In one embodiment, the digital-to-analog converter is configured to convert a control signal from the controller 50 to an electrode signal to the electrodes 76.

[0109] In one embodiment, the electronic optical lens assembly includes a plurality of plates 60 each having an array of apertures for beam paths to pass through and an array of lenses configured to control the lensing at the respective beam passages 84. In one embodiment, the plate 60 is a lens plate configured to perform a lensing function at the apertures 86A, 86B. The lenses can be connected to a common controllable potential. In such an arrangement, the plate can have a circuit connected to the electrodes assigned to each aperture. In another arrangement, at least the surface of the plate can be made of an electrically conductive material so that the surface of the plate acts as a common electrode, for example, for all apertures defined in the surface of the plate.

[0110] In one embodiment, the electron-optical plate 60 includes a substrate. The substrate can form a body of the electron-optical plate 60. In one embodiment, the substrate 60 has a crystalline structure. The substrate can include a material having a crystalline structure. For example, in one embodiment, the substrate includes silicon. The silicon can have a crystalline structure. In addition to or as an alternative to silicon, other materials having a crystalline structure can be used.

[0111] In one embodiment, the substrate has a regular crystalline structure. For example, silicon has a diamond cubic structure. In one embodiment, the crystalline structure has a crystal symmetry line. In one embodiment, the substrate is grown from a crystal having a regular crystalline structure. In one embodiment, the substrate is provided by cutting a crystal. For example, a crystal can be cut into a plurality of substrates. A surface of the substrate can be aligned in a crystal orientation direction.

[0112] In one embodiment, a plane of the substrate is parallel to a plane of the crystalline structure. The plane of the crystalline structure can be selected from a (100) plane, a (110) plane, and a (111) plane. For example, in one embodiment, a plane of the substrate of the electron-optical plate 60 is parallel to a (100) plane of the crystalline structure.

[0113] A (100) plane includes a (010) plane and a (001) plane. A (100) plane is equivalent to a (010) plane and a (001) plane. A substrate having a plane parallel to a (100) plane can have two crystal symmetry lines. A substrate having a plane parallel to a (100) plane can be considered to have two symmetry lines if considering atoms and bonds to other atoms. Meanwhile, a substrate having a plane parallel to a (100) plane can also be considered to have four symmetry lines if only considering atoms (without considering bonds to other atoms). Unless otherwise specified, crystal symmetry lines are described based on considering atoms and bonds to other atoms. The two crystal symmetry lines can be perpendicular to each other. As shown in FIG. 1, in one embodiment, the aperture 86B can have a slightly square shape. The slightly square shape can be due, at least in part, to the crystal symmetry lines of the (100) plane of the crystalline structure, for example, due to the manufacturing process described below. Figure 12

[0114] In one embodiment, a plane of the substrate of the electron-optical plate 60 is parallel to a (110) plane of the crystalline structure. The crystalline structure includes a (101) plane and a (011) plane. The (110) plane is equivalent to the (101) plane and the (011) plane. There can be two symmetrical crystal lines. The two symmetrical crystal lines can be perpendicular to each other. As shown in FIG. 2, in one embodiment, the aperture 86B can be a slightly rectangular shape. The rectangular shape can be due, at least in part, to the crystal structure of the (110) plane of the crystalline structure. Figure 18

[0115] ​​In one embodiment, the plane of the substrate of the electron optics plate 60 is parallel to a (111) plane of the crystal structure. The crystal structure can have at least three symmetric crystal lines. The symmetric crystal lines can have a 60° angle between them. As Figure 19 shown, in one embodiment, the aperture 86B can be slightly hexagonal in shape. The hexagonal shape can be due, at least in part, to the crystal structure of the (111) plane of the crystal structure.

[0116] As Figure 10 shown, in one embodiment, the electron optics plate 60 includes a plurality of channels 84. The channels 84 are configured for passage of a plurality of beam paths of a beam lattice through the substrate of the electron optics plate 60. The channels 84 are through channels. The channels 84 extend through the substrate. The channels 84 open to a major surface of the substrate at the apertures 86A, 86B.

[0117] Figure 12 An arrangement of electrodes 76 for a multipole is schematically shown. In one embodiment, the electron optics plate 60 includes a plurality of multipoles associated with respective channels 84. As Figure 12 shown, in one embodiment, each multipole includes a plurality of electrodes 76 for the associated channel 84. In one embodiment, the electrodes 76 are arranged around the aperture 86B when viewed in the direction of the beam path.

[0118] In one embodiment, the electrodes 76 are arranged such that a geometric symmetry line of the multipole is parallel to a respective crystal symmetry line of the crystal structure. For example, Figure 12 An aperture 86B that is slightly square in shape is shown. The slight square corresponds to crystal symmetry lines 127, 128 of the crystal structure. The crystal symmetry lines 127, 128 are parallel to geometric symmetry lines of the aperture 86B. In Figure 12 the example shown, one crystal symmetry line 127 can extend parallel to a left side 123 and a right side 124 of the square. Another crystal symmetry line 128 can extend parallel to a top side 125 and a bottom side 126 of the square.

[0119] As Figure 12 shown, the electrodes 76 are arranged to have geometric symmetry lines 121, 122. The geometric symmetry lines 121, 122 of the multipole are parallel to the crystal symmetry lines 127, 128 of the crystal structure. As Figure 12 shown, the electrodes 76 are arranged to have a geometric symmetry line 121 that extends parallel to a left side 123 and a right side 124 of the square shape of the aperture 86B (i.e., downward through a middle of the square shape as Figure 12 shown). The electrodes 76 can be arranged such that the multipole has another geometric symmetry line 122 that extends parallel to a top side 125 and a bottom side 126 of the square shape of the aperture 86B (i.e., horizontally through a middle of the square shape as Figure 12The square-shaped middle portion).

[0120] In one embodiment, the multipole comprises a further geometric symmetry line. For example, Figure 12 The illustrated arrangement has a further geometric symmetry line 129 extending diagonally through the middle of the aperture 86B.

[0121] In one embodiment, the geometric symmetry lines 121, 122 of the multipole are relative to the respective channel 84. In one embodiment, the electrodes 76 are arranged relative to the respective channel 84. In one embodiment, the electrodes 76 are arranged around an axis 130 through the channel 84 of the substrate and / or around a respective beam of the plurality of electron beams through the substrate.

[0122] In one embodiment, the individual multipole is positioned relative to the respective channel 84. For example, the electrodes 76 can be positioned around the channel 84. In one embodiment, the electrodes 76 are positioned around a beam path of a respective electron beam of the plurality of electron beams through the respective channel 84.

[0123] By aligning the electrodes 76 of the multipole with the crystal orientation of the substrate of the electron optical plate 60, aberrations due to the non-circular shape of the aperture 86B can be better corrected / compensated. In other words, the effect or impact of aberrations due to the rotational asymmetric shape of the aperture 86B can be reduced or improved if not prevented (i.e. corrected). This can improve the resolution of the electron optical device comprising the electron optical plate 60.

[0124] It is desirable that embodiments of the invention achieve an improved resolution of the manipulation of the electron beams by the electron optical plate 60. It is desirable that embodiments of the invention improve the correction of electron optical aberrations such as octupole aberrations.

[0125] It is desirable that embodiments of the invention achieve a multipole orientation that is more optimized for compensating for aberration effects caused by etching such as anisotropic etching. Anisotropic etching can cause holes on one side of the plate to have a different same shape as holes on the other side. For example, the diameter and / or shape can be different. Anisotropic etching can result from a dependence on etch speed along a crystal (symmetry) line. It is desirable that embodiments of the invention achieve an improved correction of octupole aberrations without requiring a multipole having at least sixteen (16) electrodes 76. Multipoles having at least sixteen (16) electrodes 76 are more difficult to manufacture compared to multipoles having a lower number of electrodes 76. It is desirable that embodiments of the invention make it easier to manufacture a plate 60 that is capable of correcting octupole aberrations.

[0126] It is desirable that embodiments of the invention achieve an increased tolerance of the etching process of the channels 84 of the electron optical plate 60. For example, the tolerance of the circularity of the apertures 86A, 86B, the diameter of the apertures 86A, 86B and / or the straightness of the walls of the channels 84 can be increased.

[0127] It is expected that embodiments of the present application increase the design freedom of other components of the electron-optical device. For example, the orientation of the deflector can be chosen more freely without reducing the electron-optical performance.

[0128] The features in the electron-optical plate 60 can be manufactured using technology from micro-electro-mechanical systems (MEMS), i.e. using MEMS manufacturing technology. These manufacturing technologies produce small structures with high precision, but have imperfections, for example with respect to the intended design. Some of these imperfections can be caused by the processing steps used. MEMS manufacturing technology creates features with dimensions in the range of about 1 μιη to about 500 μιη.

[0129] As shown in Figure 10 and Figure 15 In one embodiment, the substrate comprises opposing major surfaces 82A, 82B. The opposing major surfaces 82A, 82B are connected by a channel 84. In one embodiment, the channel 84 terminates at an aperture 86A, 86B in the major surfaces 82A, 82B. In one embodiment, the substrate is planar. In one embodiment, the shape of the aperture 86A at one major surface 82A is different from the aperture 86B at the other major surface 82B. In one embodiment, the apertures 86A, 86B defined by the respective channels 84 in the different major surfaces 82A, 82B are different.

[0130] Figure 15 The electron-optical plate 60 is shown schematically. The shape of the aperture 86A at one major surface 82A of the plate 60 can be different from the aperture 86B at the other major surface 82B of the plate 60. This difference can be caused by unintended imperfections of the manufacturing, for example by processes used in manufacturing MEMS-type components.

[0131] The present inventors have noted that the technology used to form channels through a plate can result in subtle differences in the shape of the apertures defined at the ends of the channels (or the apertures in the surface of the plate through which the channels extend; or the apertures in the opposing surface of the plate defined by the intersection of the channel and the opposing surface). To illustrate, the differences can be exaggerated in Figure 15 In the case of channels having a relatively high aspect ratio (i.e. channels that are relatively long compared to their diameter), such differences can be formed in particular; or the size of the distance between the apertures on the opposing surface relative to the cross-sectional dimension of the apertures (i.e. the cross-sectional dimension of the channel at any point between the apertures). Such effects can have more significant consequences, for example an electrode 76 extending through the channel from an aperture 86A towards another aperture 86B, for example extending between the two apertures 86A, 86B.

[0132] Such a channel can be formed in the plate 60, for example, by an etching process performed from one side of the plate 60. That is, an aperture is formed by etching a channel through the plate, for example, from one surface of the plate to the opposite surface. In such embodiments, the shape of the channel can be controlled with higher precision at the beginning of the channel (i.e. where the etching of the channel starts, for example at the start aperture) than at the end of the channel (i.e. where the etching of the channel finishes, for example at the end aperture). That is, the shape of the cross-section of the channel can change (e.g. in shape and / or size and / or orientation with respect to a frame of reference of the surface in which the start aperture is formed) with increasing distance from the start aperture. This results in the channel having differently formed apertures (e.g. different in shape, size and / or orientation) at each end. That is, the two apertures (e.g. the start aperture and the end aperture) can have different forms (e.g. different in shape, size and / or orientation). The present inventors have observed that this can result in unwanted aberrations in a charged particle beam if no or insufficient countermeasures are taken. It is desirable that embodiments of the present invention allow for compensating for such unwanted aberrations.

[0133] Such a difference in the apertures in the facing surfaces can result in the facing surfaces having apertures that do not match in shape to each other, for example having as Figure 15 indicated and with reference to Figure 15 described plates, which are present in Figure 10 indicated and with reference to Figure 10 described arrangements. The electric field between the surfaces surrounding such facing mismatched apertures can generate aberrations in a beam passing through the facing apertures; that is, the electric field is perturbed by the shape mismatch. This perturbation can be observed as an aberration.

[0134] The difference between the nominal shape and the perturbed shape can be relatively small. For example, the average azimuthal variation of the radius of the apertures having the perturbed shape can represent less than 10%, optionally less than 5%, optionally less than 1% of the average or absolute radius of the corresponding nominal shape, relative to an axis normal to the plane of the plate 60 and passing through the geometric center of the aperture. For example, where the nominal shape is a perfect circle, the perturbed shape can have an average azimuthal radius variation of less than 10%, optionally less than 5%, optionally less than 1%. In one embodiment, within each set of channels 84, the apertures 86A having the nominal shape (or simply the nominal shape apertures) are more similar in shape than any of the apertures 86B having the perturbed shape (or the perturbed shape apertures). Additionally or alternatively, in one embodiment, within each set of channels 84, the apertures 86B having the perturbed shape (or the perturbed shape apertures) are more similar in shape than any of the apertures 86A having the nominal shape (or the nominal shape apertures). For example, the nominal shape apertures can have substantially the same shape; the perturbed shape apertures can have substantially the same shape; the nominal shape apertures and the perturbed shape apertures can have substantially different shapes.

[0135] In some embodiments, as described above, the channels 84 defined in the plate 60 can be obtained in each plate by an etching process. The etching process can produce different shaped apertures 86A, 86B in the major surfaces 82A, 82B of the plate 60. The channels 84 can be etched such that the shape of the apertures on the major surfaces on opposite sides of the plate are different. The channels 84 can be referred to as etched channels. Defects in the etching process can result in different shapes of the apertures. The recipe for the etching process can be refined to reduce or eliminate the difference in shape, but this would be time consuming and / or expensive to implement. The impact of defects in the etching process can be greater in forming the nominal shape than in forming the perturbed shape. The apertures at the channel end where the etching begins can have the nominal shape, while the apertures at the other end of the channel (where the etching ends) can have the perturbed shape. It can be more difficult to etch the end aperture accurately, for example by etching a channel through a thick substrate (which can be referred to as a “deep channel” or deep etch). That is, it can be challenging to maintain the cross-sectional shape of the starting aperture (e.g., as the nominal shape) as the cross-sectional shape of the channel when etching the end aperture by such a deep etch, especially for the entire depth of the etch and / or channel; thus, the end aperture can have the perturbed shape.

[0136] In one embodiment, the nominal shape is the same for two or more, optionally for all, channels 84, at least within a group of channels. The nominal shape can be, for example, circular or elliptical. The nominal shape is not particularly limited and will be chosen according to the electron optical requirements of the stack 64. As mentioned above, these requirements can include correction of aberrations. For different charged particle beams, it is desirable that the correction of aberrations can be performed using different shaped apertures when there is a field between the facing surfaces. In one embodiment, this correction can be in the range of 0.1% to 1% of the aperture size. Thus, the nominal shape of two or more groups of channels 84 can be different. Optionally or additionally, the nominal shape of two or more groups of channels 84 can be the same.

[0137] The inventors have found that the perturbation shape includes a perturbation component that depends on the crystal symmetry of the plate 60. The perturbation component can be the dominant component of the perturbation. In some embodiments, the perturbation shape includes a perturbation component having a rotational symmetry of second order or higher. In some embodiments, the perturbation shape includes a perturbation component having a rotational symmetry of less than 10th order. In one embodiment, the perturbation component has a rotational symmetry of 4th order or a multiple of 4th order. This has been found to be the case where the plate 60 consists of, consists essentially of, or includes silicon. In one embodiment, the perturbation component has a rotational symmetry of 6th order or a multiple of 6th order. This can occur for different crystal orientations within the plate 60. For example, where the silicon in the plate 60 is oriented such that the major surface of the plate 60 is perpendicular to the

[111] crystal direction, the crystal structure parallel to the plane of the plate 60 will have hexagonal symmetry and contribute a perturbation component having a rotational symmetry of 6th order, as shown in Figure 19 More generally, in one embodiment, the perturbation component has a rotational symmetry determined by the crystal structure of the material of the plate, for example the crystal orientation of the material of the plate. Thus, this perturbation component can depend on the crystal orientation within the plate, for example relative to the major surface of the plate 60 and the order of symmetry of the crystal structure of the material.

[0138] As mentioned elsewhere, in one embodiment, the electron optical device is for projecting an electron beam along a beam path to a sample location. However, it is immaterial (e.g. not essential) that there are multiple electron beams projected along multiple beam paths. In an alternative embodiment, the electron optical device is for projecting a single electron beam along a single beam path to a sample location. The electron optical plate 60 can have a single channel 84 configured for the beam path of the electron to pass through the substrate of the electron optical plate 60. In one arrangement, the plate can take the form of a cylinder, through which the single channel is defined, for example along the axis of the cylinder, for example as a common axis of the channels 84.

[0139] As mentioned elsewhere, in one embodiment, the electron optical device is for projecting an electron beam along a beam path to a sample location. However, it is immaterial (e.g. not essential) that there are multiple electron beams projected along multiple beam paths. In an alternative embodiment, the electron optical device is for projecting a single electron beam along a single beam path to a sample location. The electron optical plate 60 can have a single channel 84 configured for the beam path of the electron to pass through the substrate of the electron optical plate 60. In one arrangement, the plate can take the form of a cylinder, through which the single channel is defined, for example along the axis of the cylinder, for example as a common axis of the channels 84. Figure 10 , Figure 11 and Figure 15As shown, in one embodiment, each channel 84 has a diameter that is no greater than the thickness of the substrate (or plate) through which the channel 84 extends. The channels 84 can be referred to as high aspect ratio channels 84. The channels 84 can be relatively long and narrow.

[0140] Thicker substrates have longer channels 84 extending therethrough. The longer channels 84 can be expected to have more pronounced non-circular shaped apertures 86B. For example, the longer channels 84 can be expected to have more square shaped apertures 86B. Aberrations associated with the non-circular shape of the aperture 86B and / or the non-circular cross-section of the channel 84 are expected to be more pronounced for longer channels 84. Embodiments of the present invention are expected to be particularly advantageous for deep substrates.

[0141] It is not necessary for the diameter of the channel 84 to be no greater than the thickness of the substrate; i.e., it is not necessary for the size of the diameter to be less than or equal to the size of the thickness of the substrate. In alternative embodiments, each channel 84 has a diameter that is greater than the thickness of the substrate through which the channel 84 extends; i.e., the size of the diameter is greater than the size of the thickness of the substrate. Even thin substrates can be expected to have associated fourth order aberrations. Embodiments of the present invention are expected to improve compensation / correction for such aberrations, e.g., reduce such compensation / correction if not completely correcting for such aberrations.

[0142] As shown, in one embodiment, the electrode 76 is positioned in the channel 84 to provide at least a portion of the surface of the channel 84, e.g., substantially the entire surface of the channel 84. Figure 11 As shown, in one embodiment, the electrode 76 extends in a direction through the substrate of the electron optical plate 60. Figure 11

[0143] As shown, in one embodiment, the electrode 76 extends to at least partially define a channel wall, e.g., a surface of the channel wall. In one embodiment, the channel wall defines the channel 84 in a thickness direction of the substrate, which can be the same as the direction of the path of the charged particle beam. In one embodiment, each channel 84 has a diameter that is as large as or less than (or no greater than) the extent to which the electrode 76 extends along the surface of the channel in the thickness direction, e.g., the electrode 76 extends along the channel wall in the thickness direction of the substrate. For example, as shown, in one embodiment, the electrode 76 extends along the channel wall in the thickness direction of the substrate. Figure 11 As shown, in one embodiment, the electrode 76 extends along the channel wall in the thickness direction of the substrate. For example, as shown, in one embodiment, the electrode 76 extends along the channel wall in the thickness direction of the substrate. Figure 11 As shown, in one embodiment, the electrode 76 extends along the channel wall in the thickness direction of the substrate. For example, as shown, in one embodiment, the electrode 76 extends along the channel wall in the thickness direction of the substrate.

[0144] As shown, in one embodiment, the electrode 76 extends to at least partially define a channel wall, e.g., a surface of the channel wall. In one embodiment, the channel wall defines the channel 84 in a thickness direction of the substrate, which can be the same as the direction of the path of the charged particle beam. In one embodiment, each channel 84 has a diameter that is as large as or less than (or no greater than) the extent to which the electrode 76 extends along the surface of the channel in the thickness direction, e.g., the electrode 76 extends along the channel wall in the thickness direction of the substrate. For example, as shown, in one embodiment, the electrode 76 extends along the channel wall in the thickness direction of the substrate. Figure 10 and Figure 15 ​As shown, in one embodiment, the channels 84 and multipoles are arranged in an array. In one embodiment, the channels 84 and multipoles are arranged in a grid, for example the array can be referred to as a grid. For example, the array can be a two-dimensional array, for example an array of channels. For example, the grid can have at least two axes; that is, the channels can be arranged in a grid having two or more axes. Reference to a grid of channels corresponds to the relative position of a plurality of beams (for example a grid of beams).

[0145] Figure 10 and Figure 15 Only a portion of the array of channels 84 is shown. In Figure 10 and Figure 15 In the arrangement shown, the channels 84 and multipoles are arranged in a grid having two axes. The axes are perpendicular to each other. The grid can be a square grid or a rectangular grid. In alternative embodiments, the grid can have at least three axes. For example, the grid can be a hexagonal grid.

[0146] In one embodiment, the grid includes at least three columns. In one embodiment, the grid includes at least five columns, for example seven columns, eleven columns or more columns. In one embodiment, the grid includes at least three rows. In one embodiment, the grid includes at least five rows, for example seven rows, eleven rows or more rows. For example, in one embodiment, the grid is a 3x3 grid or a 5x5 grid or a 7x7 grid or an 11x11 grid or a 100x100 grid or an NxN grid, where N is any reasonable natural number. The grid can have an equal number of columns and rows. Alternatively, the number of columns can differ from the number of rows. The grid can have a hexagonal arrangement, with a further third axis. Such a hexagonal grid can have the same features as described for a rectangular grid having two axes. Such a grid can have the same number of lines as rows and / or columns, for example 11x11x11. Such a hexagonal grid can have a hexagonal profile.

[0147] In one embodiment, the columns extend in a direction corresponding to one axis of the grid. In one embodiment, the rows extend in a direction corresponding to one axis of the grid. When the grid is a hexagonal grid, the position of the channels 84 can be offset relative to the channels 84 of an adjacent row, for example when considering the position of the channels along a rectangular axis. Alternatively, when considering the position of the channels in a hexagonal grid having axes, the rows, channels and lines of channels extend in a direction corresponding to the hexagonal grid.

[0148] In one embodiment, the arrangement (e.g. array or grid) of multipole can have a central axis. The central axis can correspond to a central axis of the electron optical device 41. In one embodiment, one of the channels 84 is located on the central axis. For example, when the multipole is arranged in a 3x3 grid, then a centrally located channel, e.g. a centrally located channel 84 towards the center of the grid, can be located coincident with the central axis. Such a centrally located channel can be located within a range of distances from the center of the beam grid; such a range can be derived from manufacturing tolerances when manufacturing the beam grid. In one embodiment, the center of the beam grid corresponds to the location of the central axis.

[0149] For each channel 84, an imaginary straight line (or line) connects the center of the channel 84 and the center of the grid (i.e. the central axis). The straight line is perpendicular to the central axis. In one embodiment, for at least one channel 84, and optionally for all channels 84, the straight line is parallel to (e.g. coincident with) a geometric line of symmetry of the multipole.

[0150] In one embodiment, the imaginary straight line (or line) bisects the electrodes 76 of the multipole associated with the channel 84. Alternatively, the straight line can bisect the gap between adjacent electrodes 76 of the multipole corresponding to the channel 84. In one embodiment, the electrodes 76 of different multipoles can be grouped to share a common driver. The driver can be configured to drive the electrodes 76 of the multipole, e.g. by applying an electric potential to the electrodes 76. The electric potential is applied to facing surfaces of the electron optical plate; thus, a field is generated between the facing plates, e.g. between the facing surfaces of the facing plates. By having the straight line bisect the electrodes or gap, the multipole is oriented to optimize the ease of drive control.

[0151] In one embodiment, for at least one channel 84, and optionally for all channels 84, the imaginary straight line (or line) is parallel to (e.g. coincident with) a crystal line of symmetry of the crystal structure of the substrate.

[0152] In one embodiment, for at least one of the channels 84, the angle between the crystal line of symmetry and the straight line is greater than (Z / N) 180° and less than ((Z+1) / N) 180°. Such an angle can be referred to as a relative angle. Z is zero or a positive natural number. N is the number of electrodes 76 of the multipole associated with the channel 84. For example, when there are eight electrodes 76 (e.g. as shown in FIG. 4), then N is 8, and the relative angle is 22.5°, i.e. 180° / N = 22.5°. In the arrangement shown in FIG. 4, the crystal line of symmetry is at an angle of 22.5° to the straight line. Figure 12 Figure 12 In one embodiment, for at least one of the channels 84, the angle between the crystal line of symmetry and the straight line is greater than (Z / N) 180° and less than ((Z+1) / N) 180°. Such an angle can be referred to as a relative angle. Z is zero or a positive natural number. N is the number of electrodes 76 of the multipole associated with the channel 84. For example, when there are eight electrodes 76 (e.g. as shown in FIG. 4), then N is 8, and the relative angle is 22.5°, i.e. 180° / N = 22.5°. In the arrangement shown in FIG. 4, the crystal line of symmetry is at an angle of 22.5° to the straight line. Figure 12 ​The longitudinal (i.e., up / down direction) in the plane of the plane representation of the surface and the lateral (i.e., left / right direction) in the plane of the same surface extend 127, 128. In one embodiment, the straight line (connecting the center of the channel 84 and the center of the grid) forms an angle with the longitudinal direction and the lateral direction (e.g., up / down direction and left / right direction) that is an integer multiple of 22.5°; i.e., not an integer multiple of 22.5° (i.e., not 22.5°, 45°, 67.5°, 90°, 112.5°, 135°, 157.5°, or 180°). The channel 84 is located such that if the electrodes 76 are oriented so as to optimize ease of drive control (e.g., if the electrodes 76 are oriented so that the straight line bisects the electrodes or the gap between the electrodes), the electrodes 76 of its associated multipole will not be aligned with the crystal structure. The multipole is oriented so as to improve correction of aberrations, e.g., reduce correction of aberrations (if any).

[0153] As shown in Figures 12 to 14 and Figures 16 to 19 in one embodiment, each multipole includes at least eight electrodes 76, desirably an even number of electrodes, more desirably a number of electrodes that is a multiple of four. For example, as shown in Figure 12 in one embodiment, each multipole includes eight electrodes 76.

[0154] Figure 13 An alternative arrangement of multipole electrodes 76 is shown schematically. As can be seen from a comparison between Figure 12 and Figure 13 the multipole electrodes 76 shown in Figure 13 are effectively rotated relative to the positions of the electrodes 76 shown in Figure 12 The relative angle can be 22.5° compared to the positions of the electrodes 76 shown and described with reference to Figure 12 In the arrangement shown in Figure 13 the electrodes 76 are arranged such that the geometric symmetry lines of the multipole are parallel to the corresponding crystal symmetry lines of the crystal structure. The crystal symmetry lines extend in the longitudinal direction (i.e., up / down direction) and the lateral direction (i.e., left / right direction) of the figure. The geometric symmetry lines 121, 122 of the multipole extend in the longitudinal direction and the lateral direction (in addition to in other directions).

[0155] It is expected that a multipole having eight electrodes 76 achieves compensation / correction of second order aberration properties. By orienting the geometric symmetry lines relative to the crystal symmetry lines, it is expected that embodiments achieve compensation / correction of fourth order aberrations.

[0156] Figure 14 is a schematic representation of an arrangement of electrodes 76 of another embodiment of a multipole. As Figure 14As shown, in one embodiment, each multi-pole has 12 electrodes. In one embodiment, the multi-poles are configured to compensate / correct for properties of third order aberrations. In alternative arrangements, Figure 14 The electrodes 76 as shown can be rotated relative to Figure 14 The positions of the electrodes 76 as shown are rotated by a relative angle about the aperture 86B. Such a relative angle can be 15° compared to the positions of the electrodes 76 without the relative angle applied. (For example, this can be similar to Figure 13 The electrodes 76 as shown are rotated compared to Figure 12 The electrodes 76 as shown are rotated compared to

[0157] The number of electrodes 76 need not be 8 or 12. For example, in one embodiment, one or more multi-poles have, for example, 10 electrodes or 14 electrodes. When the number of electrodes 76 is 8 or 12 (e.g., compared to the number of electrodes being 10 or 14), it is expected to be easier to properly control the electric potentials applied to the electrodes 76 in order to compensate for properties of aberrations. The electric potentials are applied to facing plates in order to generate a field between the facing plates, for example, at a mis-matched facing aperture.

[0158] In one embodiment, the crystal structure of the substrate has a four (4), two (2), or six (6) fold rotational symmetry. For example, when the plane of the substrate is parallel to the (100) plane of the crystal structure, then the crystal structure can have a four-fold rotational symmetry, i.e., a 4th order rotational symmetry. When the plane of the substrate is parallel to the (110) plane of the crystal structure, then the crystal structure can have a two-fold rotational symmetry, i.e., a 2nd order rotational symmetry. When the plane of the substrate is parallel to the (111) plane of the crystal structure, then the crystal structure of the substrate can have a six-fold rotational symmetry, i.e., a 6th order rotational symmetry.

[0159] In one embodiment, the controller 50 is configured to control the power supply to apply electric potentials to the electrodes 76. Figure 16 is Figure 12 Another view of the arrangement of the electrodes 76 of the multi-poles as shown. In one embodiment, the controller 50 is configured to control the electric potentials applied to the electrodes 76 in order to compensate for properties of aberrations. In one embodiment, the aberrations can be electron optical aberrations in a beamlet grid comprising a plurality of beamlets. In one embodiment, the aberrations are electron optical aberrations of respective beamlets of the plurality of beamlets.

[0160] The properties of the aberrations can be a type of the aberrations. The properties of the aberrations can be a magnitude of the aberrations. The properties of the aberrations can be a proportion of the aberrations. Some aberrations can remain even after correction / compensation.

[0161] In an embodiment, the electro-optical aberration is associated with other plates 60 of a stack 64 including the electro-optical plate 60. The other plates can be upstream or upstream of the electro-optical plate 60. The other plates can abut the electro-optical plate 60. The other plates and the electro-optical plate 60 can be a stack of plates, i.e., sequentially abutting plates, for example, with additional plates interleaved with the other plates and the electro-optical plate 60. The other plates can be from a different component including a plurality of plates or from electro-optical plates including the electro-optical plate 60. In these different arrangements, the other plates and the electro-optical plate operate on the same beam, for example, operate on the same beamlet. In an embodiment, the electrodes of a respective channel in the electro-optical plate 60 are configured to be controlled to compensate, e.g., correct or pre-compensate, an electro-optical aberration of the respective beamlet. The electro-optical plate 60 can be used to correct an aberration caused by one or more other components of the electron-optical device 41.

[0162] In an embodiment, the controller 50 is configured to control the electric potential applied to the electrodes 76. The electric potential is applied to facing plates so as to generate a field between the facing surfaces, for example, at a misaligned facing aperture. The electric potential can be based on a base electric potential and a compensation electric potential for compensating a property of an aberration of a respective charged particle beam. For example, the compensation electric potential can be used to correct or pre-compensate a property of an aberration. In an embodiment, the compensation electric potentials of a plurality of electrodes are equal. For example, in an embodiment, the compensation electric potentials of a plurality of electrodes 76 of an individual multipole of a grid are equal. For example, in an embodiment, the compensation electric potentials of a plurality of electrodes 76 of a multipole of a grid are equal. For example, in an embodiment, the compensation electric potentials of a plurality of electrodes 76 of a multipole of a grid are equal. Figure 16 In the illustrated arrangement, in an embodiment, the compensation electric potentials of the electrodes 76a can be equal. The compensation electric potentials applied to the other electrodes 76b can be equal. The compensation electric potential applied to the electrodes 76a can be different from the compensation electric potential applied to the other electrodes 76b. The electric potentials applied to the different electrodes 76a to 76c can include an operating electric potential and a compensation electric potential. The respective operating electric potentials applied to the different electrodes 76a to 76c can apply an operation to a beam having a path through a plurality of apertures 86B, for example, deflection, beam focusing, focusing of a beam within a beamlet.

[0163] In an embodiment, the compensation electric potentials of a plurality of electrodes 76 of a multipole of a grid are equal.

[0164] In an embodiment, the electrodes 76a to which equal compensation electric potentials are applied form a structure having an n-fold electrode rotational symmetry. The rotational symmetry can be about an axis of the respective channel 84. For example, in an embodiment, the electrodes 76a to which equal compensation electric potentials are applied form a structure having a 4-fold electrode rotational symmetry. Figure 16 In the illustrated arrangement, the electrodes 76a have a 4-fold electrode rotational symmetry. In an embodiment, the crystal structure of the substrate has an n-fold material rotational symmetry. The material rotational symmetry can be about an axis in a direction orthogonal to the plane of the substrate. The order of the material rotational symmetry can be equal to the order of the electrode rotational symmetry.

[0165] In one embodiment, the geometric symmetry lines 121, 122 of the multipole correspond to the rotational symmetry of the electrodes. In one embodiment, the crystal structure of the substrate has crystal symmetry lines 127, 128 that correspond to the rotational symmetry of the material. The electrodes 76 can be controlled such that electrodes that are similarly positioned with respect to the symmetry can be controlled in a similar manner. It is expected that embodiments of the present invention facilitate control of multipole.

[0166] Figure 17 A multipole is schematically illustrated with twelve (12) electrodes 76, for example with six-fold reflection symmetry, providing three groups of electrodes depending on how they are controlled. In one embodiment, equal compensation potentials are applied to the electrodes 76a. Similarly, equal compensation potentials can be applied to the electrodes 76b. Similarly, equal compensation potentials can be applied to the electrodes 76c. The electrodes 76 are grouped according to their position with respect to the symmetry of the multipole. The rotational displacement between adjacent electrodes that are members of different groups can be similar, for example about 30 degrees. In each group, the electrodes can be applied with the same compensation potential. However, different compensation potentials can be applied to different groups, for example as shown and described in Figure 16 Figure 16

[0167] As Figure 9 shown, in one embodiment, the stack 64, for example of the module 55, can include at least one other plate 60 stacked with respect to the electron optical plate 60. In one embodiment, at least one spacer 70 for supporting and / or electrically isolating the electron optical plate can be stacked with respect to the electron optical plate 60. In one embodiment, the other plate defines a plurality of channels therein, the channels including apertures having varying cross-sections along the respective channels. In one embodiment, the electron optical plate 60 is configured to correct properties of aberrations generated in the plurality of channels of the other plate.

[0168] In one embodiment, the electron optical plate 60 is configured to be positioned upstream of the plate and to compensate for properties of aberrations generated by the respective beam passing through the other plate. Alternatively, the electron optical plate 60 can be positioned downstream of the other plate and can be configured to correct properties of aberrations generated by the respective beam passing through the other plate. The electron optical plate 60 can compensate for one or more aberrations generated by the other plate upstream or downstream thereof.

[0169] Figure 18 A multipole electron optical plate 60 is schematically illustrated with a major surface parallel to the (110) plane of the crystal structure. The plane (110) has symmetry that results in a slightly rectangular (non-square or elongated) shape of the aperture 86B. In one embodiment, the multipole includes at least eight electrodes 76 for compensating for properties of aberrations due to the rectangular shape.​​

[0170] Figure 19 A multipole electron optical plate 60 is schematically illustrated having a major surface parallel to the (111) plane of the crystal structure. The plane (111) has symmetry resulting in a slightly hexagonal shape of the aperture 86B. In one embodiment, the multipole includes at least twelve (12) electrodes 76 for compensating for aberration properties due to the hexagonal shape.

[0171] In one embodiment, the electrodes 76a are applied with equal compensating potentials. Similarly, the electrodes 76b can be applied with equal compensating potentials. Different compensating potentials can be applied to the electrodes 76a compared to the electrodes 76b, for example, with reference to Figure 17 The described and illustrated, with the exception of the aperture having a slightly hexagonal shape, for example, a hexagonal perturbed shape.

[0172] In one embodiment, a method of fabricating an electron optical plate 60 is provided. The plate 60 can take any of the forms described with reference to Figures 9 to 19 The method includes etching a channel 84 in each of a plurality of plates 60. The etching process is such that the apertures 86A, 86B defined at opposite ends of each channel 84 have different shapes.

[0173] In one embodiment, the method includes forming a plurality of channels 84 for a beam path of a plurality of beams through a substrate. The substrate has a crystal structure with crystal symmetry lines. The channels 84 are located between two major sides of the substrate.

[0174] In one embodiment, the method includes forming a plurality of multipoles associated with respective channels 84. Each multipole includes a plurality of electrodes 76 for the associated channel. The electrodes are arranged such that a symmetry line of the multipole is parallel to a respective symmetry line of the crystal structure of the substrate. In one embodiment, forming the multipole includes positioning the electrodes 76 relative to the channel 84 such that a geometric symmetry line of the electrodes is parallel to a respective crystal symmetry line of the crystal structure of the substrate.

[0175] In one embodiment, the forming of the channels 84 includes an etching process. For example, the etching process can include a deep reactive ion etching. Such an etching process can result in the shape of the aperture 86B being different from a corresponding aperture 86A on the other major surface of the substrate.

[0176] While the preferred embodiments relate to arrangements in which the beam path is collimated, this is not always the case; for example, the beam path can be diverging or converging (so as to align with the respective channels through the plate). Such embodiments in a diverging path of the beam grid can include reference to Figure 3 and Figure 7The plate of the condenser lens array 231 and / or collimator 235. This embodiment in the convergence path of the beam grating may include, for example, such as... Figure 8 As shown and referenced Figure 8 The imaging element array 532. In a converging or diverging beam grid, at least one beam path is orthogonal to the plane of the plate. In one arrangement, the beam path may be controlled by electro-optical electrodes in one or more plates, such as a multi-pole array, wherein the surface of each channel and / or at least one associated aperture in the plate includes multiple electrodes that can be controlled to deflect the beam path relative to each other.

[0177] Although this specification refers to channels extending through the entire thickness of the plate, such channels or channel grids can be included in thinned areas of the plate. For example, one or two apertures of such channels or one or two apertures of each channel in the grid can be defined in a recess in the surface of the plate; thus, one or two main surfaces of the plate can be recessed.

[0178] References to components or systems that controllable manipulation of a charged particle beam in a particular manner include: configuring a controller or control system or control unit to control the component to manipulate the charged particle beam in that manner, and optionally using other controllers or devices (e.g., voltage sources and / or current sources) to control the component to manipulate the charged particle beam in that manner. For example, a voltage source may be electrically connected to one or more components to apply a potential to the components, as in the non-limiting list that includes control lens array 250, objective lens array 241, and detector array 240. Such voltage sources may be provided separately or jointly to different plates 60.

[0179] References to upper and lower, above and below, above and below, etc., should be understood as referring to the upstream and downstream directions (usually but not always perpendicular) of the charged particle beam impacting sample 208. Therefore, references to upstream and downstream are intended to indicate directions about the beam path independent of any present gravitational field. References to the beam path refer to the expected position of the corresponding beam during operation of the charged particle aperture. When referring to electro-optical elements such as electrode plates, it is generally understood that, for collimated beam paths, such references relate to the optical axis of the beam, and thus are orthogonal to the plane of the electro-optical element. For non-collimated beams, such as divergent beams, when the beam is a beam grid, the beam path can be considered as an axis relative to the beam midpoint, or an axis relative to the beam grid midpoint. Therefore, although the orientation of the beam path can be considered as an axis orthogonal to the plane of the planar electro-optical element, this is not always the case; in some embodiments, the beam path is angled (e.g., tilted) relative to such planar electro-optical elements.

[0180] The electron-optical apparatus described herein can take the form of a series of aperture arrays or electron-optical elements arranged in an array along a beam or multi-beam path. Such electron-optical elements can be electrostatic. In one embodiment, all electron-optical elements, e.g. from the last electron-optical element in the beam path before the sample to the beam-limit aperture array, can be electrostatic and / or can be in the form of an aperture array or plate array. In some arrangements, one or more electron-optical elements are fabricated as a microelectromechanical system (MEMS) (i.e. using MEMS fabrication techniques). Electron-optical elements can have magnetic elements and electrostatic elements. For example, a compound array lens can feature a macro magnetic lens that encloses a multi-beam path, with upper and lower pole plates within the magnetic lens and arranged along the multi-beam path. Aperture arrays for the beam paths of the multi-beam can be in the pole plates. Electrodes can be present above, below or between the pole plates to control and optimize the electromagnetic field of the compound lens array.

[0181] An evaluation apparatus, tool or system according to the present disclosure can comprise an apparatus that performs a qualitative evaluation (e.g. pass / fail) of a sample, an apparatus that performs a quantitative measurement (e.g. size of a feature) of a sample, or an apparatus that generates an image of a map of a sample. Examples of evaluation apparatuses, tools or systems are inspection tools (e.g. for identifying defects), review tools (e.g. for classifying defects) and metrology tools, or tools capable of performing any combination of evaluation functions associated with inspection tools, review tools or metrology tools (e.g. metrology inspection tools). It will be appreciated that the application can be applied to other types of apparatus, for example charged-particle lithography apparatus for generating a pattern on a sample.

[0182] The functionality provided by the controller or control system or control unit can be computer-implemented. Any suitable combination of elements can be used to provide the required functionality, including for example CPUs, RAM, SSDs, motherboards, network connections, firmware, software and / or other elements known in the art that allow the performance of the required computational operations. The required computational operations can be defined by one or more computer programs. The one or more computer programs can be provided in the form of media (optionally non-transitory media) storing computer readable instructions. When the computer readable instructions are read by a computer, the computer performs the required method steps. The computer can consist of a standalone unit or a distributed computing system with multiple different computers connected to each other over a network.

[0183] While the application has been described in connection with various embodiments thereof, other embodiments will be apparent to those of ordinary skill in the art from consideration of the specification and practice of the application as disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the following claims and their equivalents.

[0184] The following clauses are provided:

[0185] Clause 1. A charged-particle optical plate for a charged-particle optical device for projecting a charged-particle beam along beam paths to a sample location, the charged-particle optical plate comprising: a substrate having a crystal structure, the crystal structure having crystal lines of symmetry; a plurality of channels configured for a plurality of beam paths of a beamlet grid to pass through the substrate; and a plurality of multipoles associated with respective channels, each multipole comprising a plurality of electrodes for the associated channel, wherein the electrodes are arranged such that a geometric line of symmetry of the multipole is parallel to a respective crystal line of symmetry of the crystal structure.

[0186] Clause 2. A charged-particle optical plate for a charged-particle optical device for projecting a charged-particle beam along beam paths to a sample location, the charged-particle optical plate comprising: a substrate having a crystal structure, the crystal structure having crystal lines of symmetry; a channel configured for a beam path of a charged particle to pass through the substrate; and a multipole associated with the channel, the multipole comprising a plurality of electrodes for the channel, wherein the electrodes are arranged such that a geometric line of symmetry of the multipole is parallel to a respective crystal line of symmetry of the crystal structure.

[0187] Clause 3. The charged-particle optical plate according to clause 1 or 2, wherein a diameter of each channel is no greater than a thickness of the substrate through which the channel extends.

[0188] Clause 4. The charged-particle optical plate according to any of the preceding clauses, wherein an electrode extends to at least partially define a channel wall, wherein desirably the channel wall defines the channel in a thickness direction of the substrate.

[0189] Clause 5. The charged-particle optical plate according to clause 4, wherein a diameter of each channel is no greater than an extent to which the electrodes extend along the channel wall in the thickness direction of the substrate.

[0190] Clause 6. The charged-particle optical plate according to any of the preceding clauses, wherein the substrate comprises opposing major surfaces connected by the channels, and the channels terminate at apertures in the major surfaces, wherein desirably the substrate is planar, wherein a shape of the aperture at one of the major surfaces is different from a shape of the aperture at the other of the major surfaces.

[0191] Clause 7. The charged-particle optical plate according to any of the preceding clauses, wherein the channels and multipoles are arranged in an array and / or a grid, for example a two-dimensional array, wherein desirably the grid has at least two axes.

[0192] Clause 8, the charged particle optical panel of clause 7, wherein: the grid comprises at least three columns, optionally at least five columns; and / or the grid comprises at least three rows, optionally at least five rows, desirably wherein the columns extend in a direction corresponding to one of the at least two axes, desirably wherein the rows extend in a direction corresponding to one of the at least two axes.

[0193] Clause 9, the charged particle optical panel of clause 7 or 8, wherein for at least one of the channels, an angle between a crystal symmetry line and an imaginary straight line connecting a center of the channel and a center of the grid is greater than (Z / N) 180° and less than ((Z+1) / N) 180°, where Z is zero or a positive natural number, and N is a number of multipole electrodes associated with the channel (or an angle between a crystal symmetry line and an imaginary straight line connecting a center of the channel and a center of the grid is greater than (Z / N) 180° and less than ((Z+1) / N) 180°, where Z is zero or a positive natural number, and N is a number of the multipole electrodes associated with the channel).

[0194] Clause 10, the charged particle optical panel of any of the preceding clauses, wherein each multipole comprises at least eight electrodes.

[0195] Clause 11, the charged particle optical panel of any of the preceding clauses, wherein each multipole has eight or twelve electrodes.

[0196] Clause 12, the charged particle optical panel of any of the preceding clauses, wherein the crystal structure of the substrate has four-fold, two-fold or six-fold rotational symmetry.

[0197] Clause 13, the charged particle optical panel of any of the preceding clauses, wherein the substrate comprises silicon.

[0198] Clause 14, the charged particle optical panel of any of the preceding clauses, wherein a plane of the substrate is parallel to a plane of the crystal structure selected from the group consisting of a (100) plane, a (110) plane and a (111) plane.

[0199] Clause 15, the charged particle optical panel of any of the preceding clauses, comprising at least one electronic component comprising a plurality of layers electrically connected to at least one of the multipole, wherein the plurality of layers are desirably a plurality of circuit layers, for example the at least one electronic component comprises CMOS circuitry.

[0200] Clause 16, the charged particle optical panel of clause, comprising a microelectromechanical component.

[0201] Clause 17, A charged particle optical assembly comprising: a charged particle optical plate of any preceding clause; and a power supply configured to apply an electric potential to the electrodes.

[0202] Clause 18, The charged particle optical assembly according to clause 17, comprising: a controller configured to control the power supply to apply an electric potential to the electrodes.

[0203] Clause 19, The charged particle optical assembly according to clause 18, wherein the controller is configured to control the electric potential applied to the electrodes so as to compensate for a property of an aberration, the aberration desirably being an electron optical aberration in a beam grid comprising a plurality of beams and / or a respective beam of the plurality of beams.

[0204] Clause 20, The charged particle optical assembly according to clause 19, wherein the electron optical aberration is associated with a further plate of a stack comprising the charged particle optical plate, wherein the further plate can be upstream or downstream of the charged particle optical plate, the electrodes of a respective channel in the charged particle optical plate can be configured to be controlled to compensate, e.g. correct or pre-compensate, the electron optical aberration of the respective beam.

[0205] Clause 21, The charged particle optical assembly according to any of clauses 18 to 20, wherein the controller is configured to control the electric potential applied to the electrodes based on a base potential and a compensation potential for compensating an aberration, e.g. correcting or pre-compensating, of a respective electron beam.

[0206] Clause 22, The charged particle optical assembly according to clause 21, wherein the compensation potentials of a plurality of the electrodes, e.g. the plurality of multipole electrodes of the grid or individual multipole electrodes of the grid, desirably all electrodes of an individual multipole electrode, are equal.

[0207] Clause 23, The charged particle optical assembly according to clause 22, wherein the electrodes to which the equal compensation potentials are applied form an array having an n-fold electrode rotational symmetry, e.g. with respect to an axis of the respective channel, and the crystal structure of the substrate has an n-fold material rotational symmetry, e.g. with respect to an axis in a direction orthogonal to the plane of the substrate, wherein desirably the geometric symmetry line corresponds to the electrode rotational symmetry, wherein desirably the crystal structure of the substrate has a crystal symmetry line corresponding to the material rotational symmetry.

[0208] Clause 24, A charged particle optical stack comprising: at least one of the charged particle optical plates according to any of clauses 1 to 16, or at least one of the charged particle optical assemblies according to any of clauses 17 to 23.

[0209] Clause 25, the charged-particle optical stack of clause 24, comprising at least one other plate stacked relative to the charged-particle optical plate and / or at least one spacer for supporting and / or electrically isolating the at least one charged-particle optical plate, wherein desirably, individual spacers are between individual charged-particle optical plates and individual other plates.

[0210] Clause 26, the charged-particle optical stack of clause 25, wherein a plurality of channels are defined in the other plate, the plurality of channels comprising apertures having cross-sections that vary in shape along the respective channels, and the charged-particle optical plate is configured to correct properties of aberrations generated in the plurality of channels of the other plate.

[0211] Clause 27, the charged-particle optical stack of clause 26, wherein the charged-particle optical plate is configured to be positioned upstream of the other plate and pre-compensate the properties of the aberrations that would be generated by the respective beam passing through the other plate, or to be positioned downstream of the other plate and correct the properties of the aberrations generated by the respective beam passing through the other plate.

[0212] Clause 28, a charged-particle optical module comprising at least one of the charged-particle optical plate of any one of clauses 1 to 16, the charged-particle optical assembly of any one of clauses 17 to 23, and the charged-particle optical stack of any one of clauses 24 to 27.

[0213] Clause 29, a charged-particle optical apparatus for projecting a charged-particle beam along a beam path to a sample location, the charged-particle optical apparatus comprising at least one of the charged-particle optical plate of any one of clauses 1 to 16, the charged-particle optical assembly of any one of clauses 17 to 23, the charged-particle optical stack of any one of clauses 24 to 27, and the charged-particle optical module of clause 28.

[0214] Clause 30, a charged-particle optical device comprising at least one of the charged-particle optical plate of any one of clauses 1 to 16, the charged-particle optical assembly of any one of clauses 17 to 23, the charged-particle optical stack of any one of clauses 24 to 27, the charged-particle optical module of clause 28, and the charged-particle optical assembly of clause 29.

[0215] Clause 31, the charged-particle optical device of clause 30, comprising an actuatable stage for supporting a sample at a sample location.

[0216] Clause 32, A method of manufacturing a charged particle optical plate for a charged particle optical device for projecting a charged particle beam along a beam path to a sample location, the method comprising: providing a substrate having a crystal structure; forming a plurality of channels for a beam path through the substrate; and forming a plurality of multipoles associated with respective channels, each multipole comprising a plurality of electrodes for the associated channel, wherein the electrodes are arranged such that a line of symmetry of the multipole is parallel to a respective line of symmetry of the crystal structure of the substrate.

[0217] Clause 33, A method of manufacturing a charged particle optical plate for a charged particle optical device for projecting a charged particle beam along a beam path to a sample location, the method comprising: forming a plurality of channels for a beam path of a plurality of beams through a substrate having a crystal structure, the crystal structure having crystal lines of symmetry desirably between two main sides of the substrate; and forming a plurality of multipoles, each multipole being associated with a respective channel, each multipole comprising a plurality of electrodes for the associated channel, the multipole having a geometric line of symmetry of the electrodes relative to the channel, wherein forming the multipole comprises positioning the electrodes relative to the channel such that the geometric line of symmetry is parallel to a respective crystal line of symmetry of the crystal structure of the substrate.

[0218] Clause 34, The method of clause 32 or 33, wherein the forming of the channels comprises an etching process.

[0219] Clause 35, The method of clause 34, wherein the etching process comprises a deep reactive ion etching.

[0220] Clause 36, The method of any of clauses 32 to 35, optionally comprising providing the substrate, wherein providing the substrate comprises cutting a body having the crystal structure along a plane parallel to a plane of the crystal structure, the plane of the crystal structure being selected from the group consisting of a (100) plane, a (110) plane, and a (111) plane.

Claims

1. A charged particle optical plate for use in a charged particle optical device, the charged particle optical device being used to project a charged particle beam along a beam path to a sample location, the charged particle optical plate comprising: A substrate having a crystal structure having crystal symmetry lines; Multiple channels are configured to allow multiple beam paths of the beam grid to pass through the substrate; as well as Multiple multipoles associated with corresponding channels, each multipole including at least eight electrodes for the associated channel, wherein the electrodes are arranged such that the geometric symmetry line of the multipole is parallel to the corresponding crystal symmetry line of the crystal structure.

2. The charged particle optical plate according to claim 1, wherein the diameter of each channel is not greater than the thickness of the substrate through which the channel extends.

3. The charged particle optical plate according to claim 1 or 2, wherein the electrode extends to at least partially define a channel wall, wherein, desirably, the channel wall defines the channel in the thickness direction of the substrate.

4. The charged particle optical plate according to claim 3, wherein the diameter of each channel is not greater than the extent to which the electrode extends along the channel wall in the thickness direction of the substrate.

5. The charged particle optical plate according to any one of the preceding claims, wherein the substrate comprises opposing main surfaces connected by the channel, and the channel terminates at an aperture in the main surfaces, wherein the shape of the aperture at one of the main surfaces differs from the shape of the aperture at the other of the main surfaces.

6. The charged particle optical plate according to any one of the preceding claims, wherein the channels and multipoles are arranged in a grid, such as a two-dimensional array, wherein the grid preferably has at least two axes.

7. The charged particle optical plate according to claim 6, wherein: The grid comprises at least three columns; and The grid comprises at least three rows. The column extends in a direction corresponding to one of the at least two axes, and the row extends in a direction corresponding to one of the at least two axes.

8. The charged particle optical plate according to claim 6 or 7, wherein for at least one of the channels, the angle between the crystal symmetry line and the imaginary straight line connecting the center of the channel and the center of the grating is greater than (Z / N)180° and less than ((Z+1) / N)180°, where Z is zero or a positive natural number and N is the number of electrodes of the multipole associated with the channel.

9. The charged particle optical plate according to any one of the preceding claims, wherein the crystal structure of the substrate has fourth-order, second-order, or sixth-order rotational symmetry.

10. The charged particle optical plate according to any one of the preceding claims, wherein the plane of the substrate is parallel to the plane of the crystal structure, and the plane of the crystal structure is selected from the group consisting of the (100) plane, the (110) plane and the (111) plane.

11. The charged particle optical plate according to any one of the preceding claims, comprising at least one electronic component, the at least one electronic component comprising a plurality of layers electrically connected to at least one of the multipoles, wherein the plurality of layers are preferably a plurality of circuit layers, for example, the at least one electronic component comprising CMOS circuitry.

12. A charged particle optical component, comprising: Charged particle optical plate according to any one of the preceding claims; as well as A power source is configured to apply a potential to the electrodes.

13. The charged particle optical component according to claim 12, comprising: A controller is configured to control the power supply to apply a potential to the electrode. The controller is further configured to control the potential applied to the electrode to compensate for aberration properties, which are preferably electro-optical aberrations in a bundle grating comprising the plurality of bundles and / or corresponding bundles of the plurality of bundles.

14. A charged particle optical stack, comprising: At least one charged particle optical plate according to any one of clauses 1 to 13; as well as At least one other plate is stacked relative to the charged particle optical plate, wherein a plurality of channels are defined in the other plate, the channels including apertures having cross-sections that vary in shape along the respective channels, and the charged particle optical plate is configured to correct for aberrations generated in the plurality of channels of the other plate.

15. A method for manufacturing a charged particle optical plate, the charged particle optical plate being used in a charged particle optical device for projecting a charged particle beam along a beam path to a sample location, the method comprising: Provide a substrate with a crystal structure; Multiple channels are formed for the beam path through the substrate; as well as Multiple multipoles are formed associated with corresponding channels, each multipole including at least eight electrodes for the associated channel, wherein the electrodes are arranged such that the symmetry line of the multipole is parallel to the corresponding symmetry line of the crystal structure of the substrate.

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