Charged particle systems, methods for processing samples using multiple beams of charged particles

Abstract

A charged particle system and method for processing a sample using multiple beams of charged particles is disclosed. In one configuration, a column directs multiple sub-beams of charged particles onto a sample surface of a sample. While the sample is moved in a direction parallel to a first direction, the column is used to repeatedly scan the multiple beams across the sample surface in a direction parallel to a second direction. Thus, an elongated region on the sample surface is processed with each sub-beam. The sample is displaced in a direction oblique or perpendicular to the first direction. The process is repeated to process additional elongated regions with each sub-beam. The resulting multiple processed elongated regions define a sub-beam processing area for each sub-beam.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to European Patent Application Publication No. 20213733.7, filed December 14, 2020, and European Patent Application Publication No. 21171877.0, filed May 3, 2021, each of which is incorporated by reference in its entirety into this specification.

[0002] FIELD OF THE INVENTION

[0002] The embodiments provided herein generally relate to charged particle systems that use multiple sub-beams of charged particles. [Background technology]

[0003]

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

[0004]

[0004] Pattern inspection tools using charged particle beams have been used to inspect objects, for example, to detect pattern defects. These tools typically use electron microscopy techniques, such as scanning electron microscopes (SEMs). In an SEM, a primary electron beam of relatively high-energy electrons is targeted with a final deceleration step to land on a sample with a relatively low landing energy. The electron beam is focused as a probing spot on the sample. Interaction of the landing electrons from the electron beam with material structures at the probing spot causes electrons, such as secondary electrons, backscattered electrons, or Auger electrons, to be emitted from the surface. The generated secondary electrons can be emitted from the material structures of the sample. Scanning the primary electron beam as a probing spot across the sample surface can cause secondary electrons to be emitted across the surface of the sample. By collecting these emitted secondary electrons from the sample surface, the pattern inspection tool can obtain an image that represents the characteristics of the material structure of the surface of the sample.

[0005]

[0005] There is a general need to improve the throughput and other characteristics of charged particle tools. Summary of the Invention

[0006]

[0006] It is an object of the present disclosure to provide embodiments that assist in improving the throughput or other characteristics of charged particle tools.

[0007]

[0007] According to one aspect of the present invention, there is provided a method for processing a sample using multiple beams of charged particles provided by a column configured to direct the multiple sub-beams of charged particles onto a sample surface of the sample, the method comprising sequentially performing the steps of: (a) using the column to repeatedly scan the multiple beams across the sample surface in a direction parallel to a second direction while moving the sample in a direction parallel to the first direction a distance substantially equal to the pitch of the sub-beams in the multiple beams at the sample surface in the first direction, thereby processing an elongated region on the sample surface with each sub-beam; (b) displacing the sample in a direction oblique or perpendicular to the first direction; and (c) repeating steps (a) and (b) a plurality of times to process further elongated regions with each sub-beam, the resulting plurality of processed elongated regions defining a sub-beam processing area for each sub-beam.

[0008]

[0008] According to one aspect of the present invention, there is provided a charged particle system including a stage for supporting a sample having a sample surface and a column configured to direct a multi-beam of sub-beams of charged particles onto the sample surface, the system being configured to control the stage and column to sequentially perform the following: (a) using the stage to move the sample in a direction parallel to a first direction a distance substantially equal to the pitch of the sub-beams in the multi-beam at the sample surface in the first direction, while using the column to repeatedly scan the multi-beam in a direction parallel to a second direction across the sample surface, thereby processing an elongated region on the sample surface with each sub-beam; (b) using the stage to displace the sample in a direction oblique or perpendicular to the first direction; and (c) repeating (a) and (b) a plurality of times to process further elongated regions with each sub-beam, the resulting plurality of processed elongated regions defining a sub-beam processing area for each sub-beam.

[0009]

[0009] The above and other aspects of the present disclosure will become more apparent from the description of exemplary embodiments taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram illustrating an exemplary charged particle beam inspection apparatus. [Figure 2]

[0011] 2 is a schematic diagram illustrating an example multi-beam device that is part of the example charged particle beam inspection system of FIG. 1. [Figure 3]

[0012] 1 is a schematic diagram of an exemplary electron-optical system including a macro-collimator and a macro-scan deflector. [Figure 4]

[0013] FIG. 1 is a schematic diagram of an exemplary electron-optics array. [Figure 5]

[0014] FIG. 1 is a schematic diagram of an exemplary electron-optical system including a focusing lens array in the up-beam of the objective lens array assembly. [Figure 6]

[0015] FIG. 2 is an enlarged view of the control lens and the objective lens. [Figure 7]

[0016] FIG. 1 is a schematic cross-sectional side view of a detector module integrated with a two-electrode objective lens array. [Figure 8]

[0017] FIG. 8 is a bottom view of a detector module of the type shown in FIG. 7. [Figure 9]

[0018] FIG. 10 is a bottom view of an alternative detector module in which the beam apertures are in a close-packed hexagonal array. [Figure 10]

[0019] 8 shows an enlarged schematic cross-sectional view of a detector module for incorporation into the objective lens array of FIG. 7. [Figure 11]

[0020] 10A and 10B show schematic diagrams of a leap-scan approach for scanning sub-beams across a sample. [Figure 12]

[0021] 10A and 10B show schematic diagrams of a continuous scanning approach for scanning sub-beams across a sample. [Figure 13]

[0022] A framework for a method for processing a sample using multiple beams of charged particles is presented. [Figure 14]

[0023] The treatment of regions on the sample corresponding to sub-beam treatment areas is shown. [Figure 15]

[0024] The arrangement of sub-beams in a hexagonal lattice is shown. [Figure 16]

[0025] Sub-beam processing areas corresponding to the sub-beams configured as shown in FIG. 15 are shown. [Figure 17]

[0026] 1 illustrates alternating scanning of sub-beams within an elongated region. [Figure 18]

[0027] 10 illustrates an exemplary short-stroke movement of a sample during processing of a sub-beam processing area. [Figure 19]

[0028] 1 illustrates exemplary stages including a long-stroke stage and a short-stroke stage. [Figure 20]

[0029] 10 illustrates an exemplary long-stroke movement of a sample between the formation of different groups of sub-beam treatment areas. [Figure 21]

[0030] Exemplary locations of three groups of sub-beam processing areas are shown. [Figure 22]

[0031] 22 shows exemplary locations of three groups of sub-beam processing areas suitable for interleaving with respect to the groups of sub-beam processing areas of FIG. 21. [Figure 23]

[0032] The locations of all sub-beam processing areas corresponding to the groups in FIGS. 21 and 22 are shown. DETAILED DESCRIPTION OF THE INVENTION

[0011]

[0033] Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings, in which, unless otherwise indicated, identical numbers in different drawings represent identical or similar elements. The implementations described in the following description of exemplary embodiments do not represent all implementations consistent with the present invention. Instead, the implementations are merely examples of apparatus and methods consistent with aspects related to the present invention, as set forth in the appended claims.

[0012]

[0034] Increased computing power in electronic devices, which reduces the physical size of devices, can be achieved by significantly increasing the packing density of circuit components such as transistors, capacitors, and diodes on IC chips. This has been made possible by improvements in resolution, which allow for the creation of ever-smaller structures. For example, an IC chip in a smartphone the size of a thumbnail and available before 2019 can contain over 2 billion transistors, each less than 1 / 1000 the size of a human hair. It is therefore not surprising that semiconductor IC manufacturing is a complex and time-consuming process with hundreds of individual steps. An error in even a single step can dramatically affect the functionality of the final product. Just one "killer defect" can cause device failure. The goal of a manufacturing process is to improve the overall yield of the process. For example, to achieve a 75% yield for a 50-step process (where step can refer to the number of layers formed on a wafer), each individual step must have a yield of greater than 99.4%. If each individual step had a 95% yield, the overall process yield would be as low as 7%.

[0013]

[0035] In IC chip manufacturing facilities, while high process yields are desirable, maintaining high substrate (i.e., wafer) throughput, defined as the number of substrates processed per hour, is also essential. High process yields and high substrate throughput can be affected by the presence of defects. This is especially true when operator intervention is required to investigate the defects. Therefore, high-throughput detection and identification of microscale and nanoscale defects by inspection tools, such as scanning electron microscopes ("SEMs"), is essential to maintaining high yields and low costs.

[0014]

[0036] An SEM includes a scanning device and a detector system. The scanning device includes an illumination system, which includes an electron source for generating primary electrons, and a projection system for scanning a sample, such as a substrate, with one or more focused beams of primary electrons. Together, at least the illumination system or illumination system and the projection system or projection system may be referred to as the electron-optical system or system. The primary electrons interact with the sample and generate secondary electrons. The detector system captures the secondary electrons from the sample as it is scanned, allowing the SEM to generate an image of the scanned area of ​​the sample. For high-throughput inspection, some inspection systems use multiple focused beams of primary electrons, or multibeams. The component beams of a multibeam may be called subbeams or beamlets. A multibeam can simultaneously scan different portions of the sample. Therefore, a multibeam inspection system can inspect a sample much faster than a single-beam inspection system.

[0015]

[0037] Known implementations of multi-beam inspection devices are described below.

[0016]

[0038] The figures are schematic. Accordingly, in the drawings, the relative dimensions of components are exaggerated for clarity. In the following description of the drawings, the same or similar reference numbers refer to the same or similar components or entities, and only differences relative to individual embodiments are described. While the description and drawings are directed to electron-optical devices, it is understood that the embodiments are not used to limit the present disclosure to specific charged particles. Thus, throughout this specification, references to electrons can be considered to be references to charged particles more generally, and charged particles are not necessarily electrons.

[0017]

[0039] Reference is now made to Figure 1, which is a schematic diagram illustrating an exemplary charged particle beam inspection system 100. The charged particle beam inspection system 100 of Figure 1 includes a main chamber 10, a load lock chamber 20, an electron beam tool 40, a front end equipment module (EFEM) 30, and a controller 50. The electron beam tool 40 is located within the main chamber 10.

[0018]

[0040] The EFEM 30 includes a first load port 30a and a second load port 30b. The EFEM 30 may include one or more additional load ports. The first load port 30a and the second load port 30b may receive, for example, substrate front-opening integrated pods (FOUPs) containing substrates (e.g., semiconductor substrates or substrates made of other materials) or samples to be inspected (hereinafter, substrates, wafers, and samples are collectively referred to as "samples"). One or more robotic arms (not shown) within the EFEM 30 transport the samples to the load lock chamber 20.

[0019]

[0041] The load lock chamber 20 is used to remove gas from around the sample. This creates a vacuum, which is a local gas pressure lower than the pressure of the surrounding environment. The load lock chamber 20 can be connected to a load lock vacuum pumping system (not shown), which removes gas particles from the load lock chamber 20. Operation of the load lock vacuum pumping system allows the load lock chamber to reach a first pressure below atmospheric pressure. After the first pressure is reached, one or more robotic arms (not shown) transport the sample from the load lock chamber 20 to the main chamber 10. The main chamber 10 is connected to the main chamber vacuum pumping system (not shown). The main chamber vacuum pumping system removes gas particles from the main chamber 10 so that the pressure around the sample reaches a second pressure below the first pressure. After the second pressure is reached, the sample is transported to an electron beam tool, where it can be inspected. The electron beam tool 40 can include a multi-beam electron optical device.

[0020]

[0042] The controller 50 is electronically connected to the electron beam tool 40. The controller 50 may be a processor (e.g., a computer) configured to control the charged particle beam inspection apparatus 100. The controller 50 may also include processing circuitry configured to perform various signal and image processing functions. While the controller 50 is shown in FIG. 1 as being external to the structure including the main chamber 10, the load lock chamber 20, and the EFEM 30, it is understood that the controller 50 may be part of the structure. The controller 50 may be located within one of the component elements of the charged particle beam inspection apparatus, or the controller 50 may be distributed among at least two of the component elements. While the present disclosure provides an example of a main chamber 10 housing an electron beam inspection tool, it should be noted that aspects of the present disclosure, in a broad sense, are not limited to chambers housing electron beam inspection tools. Rather, it is understood that the principles described above may also be applied to other tools and other arrangements of apparatus operating under a second pressure.

[0021]

[0043]

[0023] Referring now to Figure 2, Figure 2 is a schematic diagram illustrating an exemplary electron beam tool 40, including a multi-beam inspection tool that is part of the exemplary charged particle beam inspection apparatus 100 of Figure 1. The multi-beam electron beam tool 40 (also referred to herein as apparatus 40) includes an electron source 201, a projection apparatus 230, a motorized stage 209, and a sample holder 207. The electron source 201 and projection apparatus 230 may collectively be referred to as an illumination apparatus. The sample holder 207 is supported by the motorized stage 209 to hold a sample 208 (e.g., a substrate or a mask) for inspection. The multi-beam electron beam tool 40 further includes an electron detection device 240.

[0022]

[0044] The electron source 201 may include a cathode (not shown) and an extractor or anode (not shown). In operation, the electron source 201 is configured to emit electrons from the cathode as primary electrons. The primary electrons are extracted or accelerated by the extractor and / or anode to form a primary electron beam 202.

[0023]

[0045] The projection device 230 is configured to convert the primary electron beam 202 into a plurality of sub-beams 211, 212, 213 and direct each sub-beam onto the sample 208. Although three sub-beams are shown for simplicity, there may be tens, hundreds, or thousands of sub-beams. The sub-beams may be referred to as beamlets.

[0024]

[0046] 1, such as the electron emission source 201, the electron detection device 240, the projection system 230, and the motorized stage 209. The controller 50 may perform various image and signal processing functions. The controller 50 may also generate various control signals for controlling the operation of the charged particle beam inspection system, including the charged particle multi-beam system.

[0025]

[0047] The projection device 230 may be configured to focus the sub-beams 211, 212, and 213 onto the sample 208 for inspection, forming three probe spots 221, 222, and 223 on the surface of the sample 208. The projection device 230 may be configured to deflect the primary sub-beams 211, 212, and 213 to scan the probe spots 221, 222, and 223 over respective scan areas within a section of the surface of the sample 208. In response to the incidence of the primary sub-beams 211, 212, and 213 on the probe spots 221, 222, and 223 on the sample 208, electrons, including secondary electrons and backscattered electrons, are generated from the sample 208. The secondary electrons typically have electron energies of 50 eV or less, and the backscattered electrons typically have electron energies between 50 eV and the landing energies of the primary sub-beams 211, 212, and 213.

[0026]

[0048] The electron detection device 240 is configured to detect the secondary electrons and / or backscattered electrons and generate corresponding signals that are sent to the controller 50 or a signal processing system (not shown), for example, to construct an image of a corresponding scanned area of ​​the sample 208. The electron detection device may be integrated into the projection apparatus or separate from the projection apparatus, and a secondary optical column is provided to direct the secondary electrons and / or backscattered electrons towards the electron detection device.

[0027]

[0049] The controller 50 may include an image processing system including an image acquirer (not shown) and a storage device (not shown). For example, the controller may include a processor, a computer, a server, a mainframe host, a terminal, a personal computer, any type of mobile computing device, etc., or a combination thereof. The image acquirer may include at least a portion of the processing functionality of the controller. Thus, the image acquirer may include at least one or more processors. The image acquirer may be communicatively coupled to the electronic detection device 240 of the apparatus 40, enabling signal communication, such as via electrical conductors, fiber optic cables, portable storage media, IR, Bluetooth, the Internet, a wireless network, a wireless radio, or a combination thereof, among others. The image acquirer may receive signals from the electronic detection device 240, process the data contained in the signals, and construct an image therefrom. Thus, the image acquirer may acquire an image of the sample 208. The image acquirer may also perform various post-processing functions, such as generating contours and superimposing indicators on the acquired image. The image acquirer may be configured to adjust the brightness and contrast of the acquired image, etc. The storage may be a storage medium such as a hard disk, a flash drive, cloud storage, random access memory (RAM), other types of computer-readable memory, etc. The storage may be coupled to the image acquirer and may be used to store raw scanned image data as original images or to store post-processed images.

[0028]

[0050] The image acquirer can acquire one or more images of the sample based on the imaging signal received from the electronic detection device 240. The imaging signal can correspond to a scanning operation to perform charged particle imaging. The acquired image can be a single image including multiple imaging areas. The single image can be saved to storage. The single image can be an original image that can be divided into multiple regions. Each region can include one imaging area that includes a feature of the sample 208. The acquired image can include multiple images of a single imaging area of ​​the sample 208 sampled multiple times over a period of time. The multiple images can be saved to storage. The controller 50 can be configured to perform image processing steps using multiple images of the same location on the sample 208.

[0029]

[0051] The controller 50 may include measurement circuitry (e.g., an analog-to-digital converter) to obtain a distribution of detected secondary electrons. The electron distribution data collected during the detection time window, in combination with the corresponding scan path data of each of the primary sub-beams 211, 212, and 213 incident on the sample surface, can be used to reconstruct an image of the sample structure under inspection. 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 may be present in the sample.

[0030]

[0052] The controller 50 may control the motorized stage 209 to move the sample 208 during inspection of the sample 208. The controller 50 may enable the motorized stage 209 to move the sample 208 in a direction, e.g., at a constant speed, preferably continuously, at least during inspection of the sample. The controller 50 may control the movement of the motorized stage 209 such that the motorized stage 209 varies the speed of movement of the sample 208 depending on various parameters. For example, the controller may control the stage speed (including its direction) depending on the characteristics of the inspection step of the scanning process.

[0031]

[0053] An embodiment of the present disclosure provides an objective lens array assembly that can be configured to focus multiple sub-beams onto a sample. The objective lens array assembly can be incorporated into the electron optics of a charged particle tool, such as a charged particle characterization tool. Such electron optics is an example of a column that directs multiple sub-beams of charged particles onto a sample surface, in the special case where the charged particles are electrons.

[0032]

[0054] FIG. 3 is a schematic diagram of an exemplary electron-optical system having an objective lens array assembly. The objective lens array assembly includes a flat element defining multiple apertures aligned along the sub-beam paths of the multi-beam. The objective lens array assembly includes an objective lens array 241. The flat element of the objective lens array assembly includes the objective lens array 241. The objective lens array 241 may include multiple flat elements. The flat elements of the objective lens array 241 may be configured to function as electrodes. The flat elements may be metallic, for example, and / or configured to be connected to a corresponding potential source. The flat elements of the objective lens array 241 may be referred to as an electrode or plate electrode array. The multiple apertures aligned along each sub-beam path may be defined in different corresponding flat elements (electrodes) of the objective lens array 241. Thus, the position of an aperture defined in one of the flat elements of the objective lens array 241 corresponds to the position of a corresponding aperture in one or more other flat elements of the objective lens array 241. Each group of apertures aligned along the sub-beam paths defines one of the objective lenses, which, in use, operate on the same sub-beam in the multi-beam. Each objective lens projects a respective sub-beam of the multi-beam onto the sample 208. The objective lens array 241 includes multiple objective lenses.

[0033]

[0055] For ease of illustration, lens arrays are generally depicted herein as arrays of ellipses. Each ellipse represents one of the lenses in the lens array. Ellipses are conventionally used to represent lenses by analogy with the biconvex shape often employed in optical lenses. However, it should be understood that in the context of charged particle mechanisms as discussed herein, lens arrays typically operate electrostatically and may not require physical elements employing a biconvex shape. As noted above, the lens array may instead include a plurality of flat elements defining apertures.

[0034]

[0056] In some embodiments, the planar elements of the objective lens array assembly further include a control lens array 250. The control lens array 250 includes a plurality of control lenses. Each control lens includes at least two planar elements (e.g., two or three planar elements configured to function as electrodes) configured to function as electrodes. The planar elements of the control lens array 250 may be connected to corresponding potential sources. The planar elements of the control lens array 250 may be referred to as electrodes. The control lens array 250 may include two or more (e.g., three) plate electrode arrays connected to respective potential sources. Each plate electrode array is mechanically connected to and electrically isolated from adjacent plate electrode arrays by a separation element, such as a spacer, which may include ceramic or glass. The control lens array 250 is associated with the objective lens array 241 (e.g., the two arrays are located near each other, mechanically connected to each other, and / or controlled together as a unit). The control lens array 250 is positioned in the up beam of the objective lens array 241. The control lens prefocuses the sub-beams (e.g., applies a focusing action to the sub-beams before they reach the objective lens array 241). Prefocusing can reduce the divergence of the sub-beams or increase the convergence of the sub-beams. In one embodiment, the electron-optics system including the objective lens array assembly is configured to control the objective lens array assembly (e.g., by controlling the potentials applied to the electrodes of the control lens array 250) so that the focal length of the control lens is greater than the separation distance between the control lens array 250 and the objective lens array 241. Thus, the control lens array 250 and the objective lens array 241 can be positioned relatively close to each other, in which case the focusing action from the control lens array 250 is weak and no intermediate focus is formed between the control lens array 250 and the objective lens array 241. The control lens array and the objective lens array operate together to form a composite focal length on the same surface. The composite action without intermediate focus can reduce the risk of aberrations.In other embodiments, the objective lens array assembly may be configured to form an intermediate focus between the control lens array 250 and the objective lens array 241 .

[0035]

[0057] A power supply may be provided to apply respective potentials to electrodes of the control lenses of the control lens array 250 and the objective lenses of the objective lens array 241 .

[0036]

[0058] Providing the control lens array 250 in addition to the objective lens array 241 provides additional degrees of freedom for controlling the characteristics of the sub-beams. For example, this additional degree of freedom is provided even when the control lens array 250 and the objective lens array 241 are disposed relatively close to each other so that no intermediate focus is formed between them. The control lens array 250 can be used to optimize the beam divergence angle with respect to the beam demagnification ratio and / or to control the beam energy delivered to the objective lens array 241. The control lens array 250 can include two or more electrodes. When there are two electrodes, the demagnification ratio and landing energy are controlled together. When there are three or more electrodes, the demagnification ratio and landing energy can be controlled individually. Thus, the control lens can be configured to adjust the demagnification ratio and / or beam divergence angle and / or landing energy on the sample of each sub-beam (e.g., by applying appropriate respective potentials to the electrodes of the control lens and the objective lens using a power supply). This optimization can be achieved without excessively adversely affecting the number of objective lenses and without excessively worsening the aberrations of the objective lenses (e.g., without reducing the strength of the objective lenses). The use of a controlled lens array allows the objective lens array to be operated at an optimal electric field strength. Note that references to demagnification ratio and opening angle are intended to refer to variations of the same parameter. In an ideal configuration, the product of the range of demagnification ratios and the corresponding opening angle is constant. However, the opening angle can be affected by the use of apertures.

[0037]

[0059] In one embodiment, the landing energy can be controlled to a desired value within a predetermined range, for example, 1000 eV to 5000 eV. The resolution of the tool can remain substantially constant as the landing energy decreases down to a minimum value, LE_min. Below LE_min, the resolution decreases because the lens strength of the objective lens and the electric field inside the objective lens must be reduced to maintain a minimum spacing between the objective lens and / or detector and the sample.

[0038]

[0060] The landing energy is preferably varied primarily by controlling the energy of the electrons exiting the control lens. The potential difference within the objective lens is preferably kept constant during this variation so that the electric field within the objective lens remains as high as possible. Furthermore, the potential applied to the control lens can be used to optimize the beam opening angle and demagnification ratio. The control lens can function to vary the demagnification ratio to account for changes in landing energy. Each control lens preferably includes three electrodes to provide two independent control variables. For example, one of the electrodes can be used to control the magnification ratio, and another electrode can be used to separately control the landing energy. Alternatively, each control lens can have only two electrodes. If there are only two electrodes, one of the electrodes may need to control both the magnification ratio and the landing energy.

[0039]

[0061] In the embodiment of FIG. 3, the electron-optics system includes a radiation source 201. The radiation source 201 provides a beam of charged particles (e.g., electrons). Multiple beams that focus on the sample 208 are derived from the beam provided by the radiation source 201. Sub-beams may be derived from the beam using, for example, a beam limiter defining an array of beam-limiting apertures. The radiation source 201 is preferably a high-brightness thermal field emitter with a good compromise between brightness and total emission current. In the illustrated example, a collimator is provided in the up-beam of the objective lens array assembly. The collimator may include a macro-collimator 270. The macro-collimator 270 acts on the beam from the radiation source 201 before the beam is split into multiple beams. The macro-collimator 270 bends each portion of the beam by an amount effective to ensure that the beam axis of each of the sub-beams derived from the beam is incident on the sample 208 substantially perpendicularly (i.e., at substantially 90° relative to the nominal surface of the sample 208). The macro-collimator 270 applies macroscopic collimation to the beam. Thus, the macro-collimator 270 may act on the entire beam rather than including an array of collimator elements, each configured to act on a different individual portion of the beam. The macro-collimator 270 may include a magnetic lens or a magnetic lens configuration including multiple magnetic lens subunits (e.g., multiple electromagnets forming a multipole configuration). Alternatively or additionally, the macro-collimator may be implemented at least in part electrostatically. The macro-collimator may include an electrostatic lens or an electrostatic lens configuration including multiple electrostatic lens subunits. The macro-collimator 270 may use a combination of magnetic and electrostatic lenses.

[0040]

[0062] In the embodiment of FIG. 3 , a macro scan deflector 265 is provided to scan the sub-beams across the sample 208. The macro scan deflector 265 deflects respective portions of the beam to scan the sub-beams across the sample 208. In one embodiment, the macro scan deflector 256 includes a macro multipole deflector, e.g., having eight or more poles. The deflection is such that the sub-beams derived from the beam are scanned across the sample 208 in one direction (e.g., parallel to a single axis, such as the X axis) or two directions (e.g., relative to two non-parallel axes, such as the X and Y axes). The macro scan deflector 265 acts macroscopically on the entire beam, rather than including an array of elements each configured to act on a different individual portion of the beam. In the illustrated embodiment, the macro scan deflector 265 is provided between the macro collimator 270 and the control lens array 250.

[0041]

[0063] Any of the objective lens array assemblies described herein may further include a detector (e.g., including the detector module 402). The detector detects charged particles emitted from the sample 208. The detected charged particles may include any of the charged particles detected by an SEM, including secondary electrons and / or backscattered electrons emitted from the sample 208. At least a portion of the detector may be adjacent to and / or integrated with the objective lens array 241. The detector may provide the sample-facing surface of the objective lens array assembly. Exemplary detector configurations are described below with reference to FIGS. 7-10. The detector and objective lens may be part of the same structure. The detector may be connected to the lens by an insulating element or directly to an electrode of the objective lens.

[0042]

[0064] In a variation on the embodiment of FIG. 3 , the objective lens array assembly may include a scan deflector array. The scan deflector array includes multiple scan deflectors. The scan deflector array 260 may be formed using MEMS fabrication techniques. Each scan deflector scans a respective sub-beam across the sample 208. Thus, the scan deflector array 260 may include a scan deflector for each sub-beam. Each scan deflector may deflect a sub-beam in one direction (e.g., parallel to a single axis, such as the X axis) or two directions (e.g., relative to two non-parallel axes, such as the X axis and the Y axis). The deflection is such that the sub-beam is scanned in one direction or two directions (i.e., one-dimensionally or two-dimensionally) across the sample 208. In one embodiment, the scan deflector array may be implemented using the scan deflectors described in EP 2425444, which is incorporated herein by reference in its entirety, particularly with respect to the scan deflector. The scan deflector array is disposed between the objective lens array 241 and the control lens array 250. A scan deflector array may be provided instead of the macro scan deflector 265. The scan deflector array (e.g., formed using MEMS fabrication techniques as described above) may be more spatially compact than the macro scan deflector 265.

[0043]

[0065] In other embodiments, both a macro scan deflector 265 and a scan deflector array may be provided. In such configurations, scanning of the sub-beams over the sample surface may be achieved by controlling the macro scan deflector 265 and the scan deflector array together, preferably synchronously.

[0044]

[0066] Providing a scanning deflector array instead of the macro scanning deflector 265 can reduce aberrations from the control lens. Aberrations can be reduced because the scanning motion of the macro scanning deflector 265 causes a corresponding movement of the beam on a beam-shaping limiter (also called a lower beam limiter) that defines an array of beam-limiting apertures in the down beam of at least one electrode of the control lens, thereby increasing the contribution to aberrations from the control lens. Instead, when a scanning deflector array is used, the beam is moved by a much smaller amount on the beam-shaping limiter because the distance from the scanning deflector array to the beam-shaping limiter is much shorter. This makes it preferable to position the scanning deflector array as close as possible to the objective lens array 241 (e.g., so that the scanning deflector array is directly adjacent to the objective lens array 241 and / or closer to the objective lens array 241 than the control lens array 250). The smaller movement on the beam-shaping limiter results in a smaller portion of each control lens being used. Therefore, the control lens contributes less to aberrations. To minimize or at least reduce the aberrations caused by the control lens, a beam-shaping limiter is used to shape the beam down from at least one electrode of the control lens. This differs structurally from conventional systems, in which the beam-shaping limiter is provided only as an aperture array that is part of or associated with the first manipulator array in the beam path, and typically generates multiple beams from a single beam from the radiation source. Despite the function of the beam-shaping limiter, sub-beams can be derived from the beam using a beam limiter that defines an array of beam-limiting apertures, for example, as described above.

[0045]

[0067] In some embodiments, such as illustrated in FIG. 3, the control lens array 250 is the first deflection or lens effect electro-optic array element in the beam path of the down beam of the radiation source 201 .

[0046]

[0068] In a variation on the embodiment of FIG. 3 or the variation described above in which a scanning deflector array is provided, a collimator element array can be provided instead of the macro-collimator 270. Each collimator element collimates a respective sub-beam. A collimator element array (e.g., formed using MEMS fabrication techniques) can be more spatially compact than the macro-collimator 270. Therefore, combining the collimator element array and the scanning deflector array can result in space savings. This space savings is desirable when multiple electron-optical systems, including objective lens array assemblies, are provided within the electron-optical system array 500, as discussed below with reference to FIG. 4. In such an embodiment, a macro-condenser lens or condenser lens array may not be necessary. In this scenario, the control lens offers the possibility of optimizing the beam divergence angle and expansion ratio for varying landing energies. Note that a beam-shaping limiter is located down-beam of the control lens array. An aperture in the beam-shaping limiter adjusts the beam current along the beam path so that the control lens's control of the expansion ratio affects the divergence angle differently. That is, the aperture in the beam-shaping limiter breaks the direct correspondence between the change in magnification and opening angle.

[0047]

[0069] In some embodiments, the collimator element array is the first deflecting or focusing electron optical array element in the beam path of the down beam of the radiation source 201 .

[0048]

[0070] The omission of deflection or lensing electron-optical array elements (e.g., lens arrays or deflector arrays) in the up beam of the control lens array 250 or the up beam of the collimator element array relaxes the requirements on the electron-optical systems in the up beam of the objective lens and on the correctors to correct for imperfections in such electron-optical systems (i.e., aberrations produced in the sub-beams by such systems). For example, some alternative configurations seek to maximize utilization of the source current by providing a condenser lens array in addition to the objective lens array (as discussed below with reference to FIG. 5). Such a condenser lens array and objective lens array imposes higher requirements on the positional uniformity of the virtual source position across the source opening angle, or requires corrective optics for each sub-beam to ensure that each sub-beam passes through the center of the corresponding objective lens in the down beam. Architectures such as that of FIG. 3 and its variations described above can shorten the beam path from the first deflection or lensing electron-optical array element to the beam-shaping limiter in the down beam to less than about 10 mm, preferably less than about 5 mm, and preferably less than about 2 mm. Shortening the beam path relaxes or removes the stringent requirements on the virtual source position over the source opening angle. An electron optical column of such an architecture, as shown and described with reference to Figures 3, 5 and 6, may include components such as an upper beam limiter 252, a collimator element array 271, a control lens array 250, a scanning deflector array 260, an objective lens array 241, a beam shaping limiter 242 and a detector array 240. One or more of these elements present may be connected to another adjacent element using a separation element, such as a ceramic or glass spacer.

[0049]

[0071] In one embodiment, as illustrated in FIG. 4 , an electron-optics array 500 is provided. The array 500 may include multiple electron-optics systems described herein. Each electron-optic system simultaneously focuses a respective multibeam onto a different region of the same sample. Accordingly, in this context, each region may correspond to a portion or part of the surface of the sample. Each electron-optic system may form multiple sub-beams from a single charged particle beam from a different respective radiation source 201. Each radiation source 201 may be a radiation source in a plurality of radiation sources 201. At least a subset of the plurality of radiation sources 201 may be provided as a radiation source array. The radiation source array may include multiple radiation sources 201 disposed on a common substrate. Simultaneously focusing multiple multibeams onto different regions of the same sample can increase the area of ​​the sample 208 that is simultaneously processed (e.g., evaluated). The electron-optics systems in the array 500 may be positioned adjacent to each other to project each multibeam onto adjacent regions of the sample 208. Any number of electron-optics systems may be used in the array 500. The number of electron-optical systems is preferably in the range of 9 to 200. In one embodiment, the electron-optical systems are arranged in a rectangular array or a hexagonal array. In other embodiments, the electron-optical systems are arranged in an irregular array or a regular array having a shape other than rectangular or hexagonal. Each electron-optical system in the array 500 can be configured in any of the manners described herein, for example, as described above, when referring to a single electron-optical system. Details of such configurations are described in European Patent Application Publication No. A20184161.6, filed July 6, 2020, which is incorporated herein by reference for its methods for incorporating and adapting objective lenses for use in multi-column configurations. In the example of FIG. 4 , each electron-optical system includes both a scanning deflector array 260 and a collimator element array 271. As noted above, the scanning deflector array 260 and the collimator element array 271 are particularly well-suited for incorporation into the electron-optical system array 500 because their spatial compactness facilitates locating electron-optical systems close to one another.A configuration having both a scanning deflector array 260 and a collimator element array 271 may be preferable to the configuration shown in Figure 3, and a preferred implementation may use a magnetic lens as the collimator 270. Incorporating a magnetic lens into an electron-optical system intended for use in an array (multi-column configuration) may be difficult.

[0050]

[0072] FIG. 5 shows a variation of the embodiment of FIG. 3 (and a variation to the embodiment described above) in which a collector lens array 231 is provided between the radiation source 201 and the objective lens array assembly. The collector lens array is thus in the upbeam of the objective lens array assembly. Such an arrangement is described in EP-A20158804.3, which is incorporated herein by reference at least with respect to the architecture shown in FIG. 4. This arrangement may be incorporated, for example, into the multi-column array of EP-A20206987.8, filed November 11, 2020, as described above with reference to FIG. 4. The collector lens array 231 includes a plurality of collector lenses. There may be tens, hundreds, or even thousands of collector lenses. The condenser lens may include a multi-electrode lens and may have a structure based on EP 1 602 121 A1, which is incorporated herein by reference, particularly for its disclosure of a lens array for splitting an electron beam into multiple sub-beams, the array providing one lens for each sub-beam. The condenser lens array 231 may be configured to generate multiple beams. The condenser lens array may take the form of at least two flat elements (which may be referred to as plates) that function as electrodes, with apertures in each plate aligned with each other and corresponding to the positions of the sub-beams. At least two of the flat elements are maintained at different potentials during operation to achieve the desired lens effect. The flat elements of the condenser lens array 231 may be referred to as a plate array.

[0051]

[0073] In one configuration, the focusing lens array is formed from an array of three plates in which charged particles have the same energy when they enter and exit each lens; this configuration can be called an Einzel lens. Therefore, dispersion occurs only within the Einzel lens itself (between the lens's entrance and exit electrodes), thereby limiting off-axis chromatic aberrations. If the focusing lens is thin, e.g., a few mm thick, the effect of such aberrations is small or negligible.

[0052]

[0074] The condenser lens array 231 may have two or more plate electrodes, each containing an array of aligned apertures. Each plate electrode array is mechanically connected to and electrically isolated from adjacent plate electrode arrays by isolation elements, such as spacers, which may comprise ceramic or glass. The condenser lens arrays may be connected to and / or isolated from adjacent electro-optical elements, preferably electrostatic electro-optical elements, by isolation elements, such as spacers, as described elsewhere herein.

[0053]

[0075] The condenser lens is separated from the module containing the objective lens (such as an objective lens array assembly as discussed elsewhere herein). If the potential applied to the bottom surface of the condenser lens is different from the potential applied to the top surface of the module containing the objective lens, a separation spacer is used to space the condenser lens from the module containing the objective lens. If the potentials are equal, a conductive element can be used to space the condenser lens from the module containing the objective lens.

[0054]

[0076] Each focusing lens in the array directs electrons into a respective sub-beam 211, 212, 213 that focuses at a respective intermediate focus. Each focusing lens forms a respective intermediate focus between the focusing lens array 231 and a respective objective lens of the objective lens array assembly. The focusing lens array 231 is preferably configured so that the sub-beam paths diverge from each other between the focusing lens array 231 and the plane of the intermediate focus. In the illustrated embodiment, a deflector 235 is provided at the intermediate focus (i.e., in the plane of the intermediate focus). The deflector 235 is configured to bend each beamlet 211, 212, 213 by an amount effective to ensure that the chief ray (which may also be referred to as the beam axis) is incident on the sample 208 substantially perpendicularly (i.e., at substantially 90° relative to the nominal surface of the sample). The deflector 235 may also be referred to as a collimator. The deflector 235 effectively collimates the paths of the beamlets, so that before the deflector the beamlets diverge with respect to one another. Down the deflector, the beamlet paths are substantially parallel to one another, i.e., substantially collimated. A suitable collimator is the deflector disclosed in European Patent Application Publication No. 20156253.5, filed February 7, 2020, which is incorporated herein by reference with respect to the application of deflectors to multi-beam arrays.

[0055]

[0077] FIG. 6 is an enlarged schematic diagram of one objective lens 300 of the objective lens array 241 and one control lens 600 of the control lens array 250. The objective lens 300 may be configured to demagnify the electron beam by a factor of more than 10, preferably in the range of 50-100 or more. The objective lens 300 includes a central or first electrode 301, a lower or second electrode 302, and an upper or third electrode 303. Voltage sources V1, V2, and V3 are configured to apply potentials to the first, second, and third electrodes, respectively. A further voltage source V4 is connected to the sample and applies a fourth potential, which may be ground. The potentials may be defined with respect to the sample 208. The first, second, and third electrodes are each provided with an aperture through which each sub-beam propagates. The second potential may be close to the potential of the sample, for example, in the range of 50 V to 200 V more positive than the sample. Alternatively, the second potential can be in a range of about +500 V to about +1,500 V more positive than the sample. A higher potential is useful when the detector is located higher in the optical column than the bottom electrode. The first and / or second potentials can be varied for each aperture or group of apertures to provide focus correction.

[0056]

[0078] In one embodiment, it is desirable to omit the third electrode. Objective lenses with only two electrodes may have smaller aberrations than objective lenses with more electrodes. Three-electrode objective lenses allow for a larger potential difference between the electrodes, thereby enabling a more powerful lens. Additional electrodes (i.e., three or more electrodes) provide additional degrees of freedom in controlling the electron trajectory, for example, to focus secondary electrons in addition to the incident beam.

[0057]

[0079] As mentioned above, it is desirable to determine the landing energy using a control lens. However, it is also possible to control the landing energy using the objective lens 300. In such cases, selecting a different landing energy changes the potential difference across the objective lens. One example of a situation in which it is desirable to partially change the landing energy by changing the potential difference across the objective lens is to prevent the sub-beams from focusing too close to the objective lens. In such a situation, there is a risk that the electrodes on the objective lens would have to be made too thin to be manufactured. The same is true for the detector at this location. This situation can arise, for example, when the landing energy is reduced. This is because the focal length of the objective lens generally scales with the landing energy used. By reducing the potential difference across the objective lens, and thereby reducing the electric field inside the objective lens, the focal length of the objective lens again increases, and the focal position moves further down the objective lens. Note that using only the objective lens limits control of the magnification ratio. Such a configuration does not allow for control of the demagnification ratio and / or the aperture angle. Furthermore, using the objective lens to control the landing energy may mean that the objective lens will operate away from the optimal electric field strength, unless the mechanical parameters of the objective lens (such as the spacing between the electrodes) can be adjusted, e.g., by changing the objective lens.

[0058]

[0080] In the illustrated configuration, the control lens 600 includes three electrodes 601-603 connected to potential sources V5-V7. The electrodes 601-603 can be spaced a few millimeters (e.g., 3 mm) apart. The spacing between the control lens and the objective lens (i.e., the gap between the lower electrode 602 and the upper electrode of the objective lens) can be selected from a wide range, e.g., from 2 mm to 200 mm or more. A small separation facilitates alignment, while a larger separation allows the use of weaker lenses and reduces aberrations. The potential V5 of the top electrode 603 of the control lens 600 is preferably maintained at the same potential as the next electron-optical element (e.g., deflector 235) in the upbeam of the control lens. The potential V7 applied to the lower electrode 602 can be varied to determine the beam energy. The potential V6 applied to the middle electrode 601 can be varied to determine the lens strength of the control lens 600 and thus control the beam divergence angle and demagnification. The lower electrode 602 of the control lens and the top electrode of the objective lens are preferably at substantially the same potential. The bottom electrodes of the sample and objective lens typically have significantly different potentials than the bottom electrode of the control lens. Electrons can be decelerated, for example, from 30 kV to 2.5 kV within the objective lens. In one design, the upper electrode V3 of the objective lens is omitted. In this case, the lower electrode 602 of the control lens and the electrode 301 of the objective lens are preferably at substantially the same potential. Note that the control lens can be used to control the beam divergence angle even when the landing energy does not need to be changed or is changed by other means. The position of the focal point of the sub-beams is determined by the combined action of each control lens and each objective lens.

[0059]

[0081] If a control lens is used to correct the electron beam divergence angle / magnification ratio, for example, rather than the condenser lens of the embodiment of FIG. 5, the collimator remains at the intermediate focal point, and there is no need to correct the collimator's astigmatism. (Note that in such a configuration, adjusting the magnification ratio results in a similar adjustment of the divergence angle, since the beam current remains constant along the beam path.) Furthermore, the landing energy can be varied over a wide range of energies while maintaining an optimal electric field strength within the objective lens. This minimizes objective lens aberrations. The strength of the condenser lens (if used) is kept constant, avoiding the introduction of additional aberrations due to the collimator not being at the intermediate focal plane or the changing electron path through the condenser lens. Furthermore, if a control lens is used in an embodiment featuring a beam-shaping limiter, such as that shown in FIG. 3 (without a condenser lens), the divergence angle / magnification ratio can be controlled in addition to the landing energy.

[0060]

[0082] In some embodiments, the charged particle tool further includes one or more aberration correctors that reduce one or more aberrations in the sub-beams. In one embodiment, each of at least a subset of the aberration correctors is located at or directly adjacent to a respective one of the intermediate foci in an embodiment of the type shown in FIG. 5 (e.g., located at or adjacent to an intermediate image plane). The sub-beams have a smallest cross-sectional area at or near a focal plane, such as the mid-plane (the plane of the intermediate foci). This provides more space for the aberration correctors than would be available elsewhere, i.e., at the up-beam or down-beam of the mid-plane (or in an alternative arrangement without a mid-plane).

[0061]

[0083] In one embodiment, an aberration corrector located at or immediately adjacent to the intermediate focus (or intermediate plane) includes a deflector to correct for the source 201 appearing to be in different positions for different beams. The corrector can be used to correct for macroscopic aberrations due to the source that prevent good alignment between each sub-beam and the corresponding objective lens.

[0062]

[0084] Aberration correctors can correct aberrations that prevent proper column alignment. Such aberrations can lead to misalignment between the sub-beams and the correctors. For this reason, it may be desirable, in addition or instead, to place the aberration correctors at or near the collecting lenses of the collecting lens array 231 (e.g., each such aberration corrector is integrated with or directly adjacent to one or more of the collecting lenses). This is desirable because the collecting lenses are close to perpendicular to or coincident with the beam aperture, so that aberrations at or near the collecting lenses still do not cause shifts of the corresponding sub-beams. However, a challenge with placing the correctors at or near the collecting lenses is that the cross-sectional area of ​​each sub-beam is relatively large and the pitch is relatively small at this location compared to locations further downstream (or down the beam). The collecting lenses and correctors can be part of the same structure. For example, they can be connected to each other using, for example, an electrically insulating element.

[0063]

[0085] In some embodiments, at least a subset of the aberration correctors are each integrated with or directly adjacent to one or more of the objective lenses or control lenses in the objective lens array assembly. In one embodiment, the aberration correctors reduce one or more of field curvature, focus error, and astigmatism. The objective lenses and / or condenser lenses and the correctors may be part of the same structure. For example, they may be connected to each other using, for example, an electrically insulating element.

[0064]

[0086] The aberration corrector may be a CMOS-based individually programmable deflector as disclosed in EP 2702595A1 or an array of multipole deflectors as disclosed in EP 2715768A2, the descriptions of beamlet manipulators in both documents being incorporated herein by reference.

[0065]

[0087] In some embodiments, the detector of the objective lens array assembly includes a detector module in the downbeam of at least one electrode of the objective lens array 241. In one embodiment, at least a portion of the detector (e.g., the detector module) is adjacent to and / or integrated with the objective lens array 241. For example, the detector module can be implemented by integrating a CMOS chip detector into the bottom electrode of the objective lens array 241. Integrating the detector module into the objective lens array assembly replaces the secondary column. The CMOS chip is preferably oriented to face the sample (due to the short distance between the sample and the bottom of the electron-optics system (e.g., 100 μm)), thereby providing the sample-facing surface of the assembly. In one embodiment, an electrode for capturing secondary electron signals is formed in the top metal layer of the CMOS device. Electrodes can be formed in other layers. CMOS power and control signals can be connected to the CMOS by through-silicon vias. For robustness, the bottom electrode preferably consists of two elements: the CMOS chip and a passive Si plate with holes. The plate shields the CMOS from high electric fields.

[0066]

[0088] To maximize detection efficiency, it is desirable to make the electrode surface as large as possible so that substantially all of the area of ​​the objective lens array 241 (excluding the aperture) is occupied by electrodes. Each electrode has a diameter substantially equal to the array pitch. In one embodiment, the electrode outline is circular, but this can be made square to maximize the detection area. The diameter of the substrate through-holes can also be minimized. The typical size of the electron beam is approximately 5 to 15 microns.

[0067]

[0089] In one embodiment, a single electrode surrounds each aperture. In another embodiment, multiple electrode elements are provided around each aperture. Electrons captured by the electrode elements surrounding an aperture may be combined into a single signal or used to generate independent signals. The electrode elements may be radially divided (i.e., forming multiple concentric rings), angularly divided (i.e., forming multiple sectors), divided both radially and angularly, or divided in any other convenient manner.

[0068]

[0090] However, increasing the electrode surface results in an increase in parasitic capacitance and therefore a decrease in bandwidth. For this reason, it may be desirable to limit the outer diameter of the electrode, especially when increasing the electrode only provides a small improvement in detection efficiency but a large increase in capacitance. Circular (annular) electrodes may offer a good compromise between collection efficiency and parasitic capacitance.

[0069]

[0091] Increasing the outer diameter of the electrode can also result in increased crosstalk (sensitivity to signals from neighboring holes). This can also be a reason to make the outer diameter of the electrode smaller, especially if enlarging the electrode only provides a slight improvement in detection efficiency but a large increase in crosstalk.

[0070]

[0092] The current of backscattered and / or secondary electrons collected by the electrode may be amplified by a transimpedance amplifier.

[0071]

[0093] An exemplary embodiment of a detector integrated into an objective lens array is shown in FIG. 7. FIG. 7 shows a schematic cross-sectional view of a portion 401 of the objective lens array. In this embodiment, the detector includes a detector module 402 that includes multiple detector elements 405 (e.g., sensor elements such as trapping electrodes). In this embodiment, the detector module 402 is located on the output side of the objective lens array, which is the side facing the sample 208. FIG. 8 shows a bottom view of the detector module 402, which includes a substrate 404 with multiple trapping electrodes 405 thereon, each surrounding a beam aperture 406. The beam apertures 406 may be formed by etching the substrate 404. In the configuration shown in FIG. 8, the beam apertures 406 are shown as a rectangular array. Alternatively, the beam apertures 406 may be arranged in a close-packed hexagonal array, as shown in FIG. 9.

[0072]

[0094] 10 shows a cross-sectional view of a portion of the detector module 402 on a larger scale. The trapping electrodes 405 form the bottom surface of the detector module 402, i.e., the surface closest to the sample. Between the trapping electrodes 405 and the main body of the silicon substrate 404 is a logic layer 407. The logic layer 407 may include amplifiers, such as transimpedance amplifiers, analog-to-digital converters, and readout logic. In one embodiment, there is one amplifier and one analog-to-digital converter per trapping electrode 405. The logic layer 407 and trapping electrodes 405 may be fabricated using a CMOS process, with the trapping electrodes 405 forming the final metallization layer.

[0073]

[0095] The wiring layer 408 is provided on the backside or inside the substrate 404 and is connected to the logic layer 407 by through-silicon vias 409. The number of through-silicon vias 409 does not need to be the same as the number of beam apertures 406. In particular, if the electrode signals are digitized in the logic layer 407, only a few through-silicon vias may be needed to provide a data bus. The wiring layer 408 may include control lines, data lines, and power lines. Note that despite the presence of the beam apertures 406, there is sufficient space for all necessary connections. The detector module 402 may also be manufactured using bipolar or other manufacturing techniques. A printed circuit board and / or other semiconductor chips may be provided on the backside of the detector module 402.

[0074]

[0096] The detector module 402 may be integrated into the bottom electrode array of the objective lens array as well as other electrode arrays. Further details and alternative configurations of detector modules integrated into objective lenses can be found in EP 20184160.8, which is incorporated herein by reference at least with respect to the detector modules and the integration of such modules within the objective lens.

[0075]

[0097] 11 and 12 illustrate schematically an exemplary method for scanning multiple beams across a sample 208. FIG.

[0076]

[0098] FIG. 11 illustrates a method that may be referred to as leap scanning. Grid positions 702 illustrate an exemplary geometry of a multibeam directed onto a sample 208 by a column (e.g., electron optics). The grid positions 702 represent the positions of subbeams in the multibeam when aligned, e.g., after alignment calibration. The pitch of the grid positions 702 is equal to the pitch of the subbeams in the multibeam on the sample surface. Each subbeam is electrostatically scanned by the column in different directions (e.g., X and Y directions) across a pitch area 704 corresponding to the subbeam. Two exemplary pitch areas 704 are labeled. The main scan area is labeled 704A. Additionally, a boundary region 704B may be provided to accommodate beam pitch non-uniformity. The boundary region 704B avoids or reduces undesirable gaps between pitch areas 704 that may otherwise result from beam pitch non-uniformity. A dashed line 703 is shown in the leftmost exemplary pitch area 704 to schematically represent a scan line along the X direction. In an alternative configuration, the pitch areas may be preferably spaced apart with minimal gaps. The scan lines may be processed sequentially, one after the other, with a step movement in the Y direction between each scan line. (In this context, "processing" a sample surface is intended to mean exposing the sample surface to the beam. For example, in a dynamic system, this is achieved by passing the beam across the sample surface, with the sample and the beam at the point of incidence on the sample surface moving relative to one another in the plane of the sample. An example of this is scanning the beam across the sample surface. Thus, the sample surface processed by the beam is the surface scanned by the beam.) References to X and Y are merely intended to indicate that scanning occurs in two different directions that are angled relative to one another, which may be orthogonal to one another. Successive scan lines may follow one line to the next, i.e., meander, or the scan lines may begin on one side of the pitch area. The process continues until each sub-beam has processed all of its pitch areas 704. The pitch areas 704 are processed in parallel by each sub-beam, i.e., the sub-beams scan their corresponding pitch areas 704 simultaneously.Once the sub-beams have finished processing the pitch area 704, the sample is moved to a different location (this may be referred to as a leap, since it involves a relatively large distance). The process (e.g., scanning) is then repeated to process the pitch area 704 at this new location of the sample. The leap may move the sample so that a different portion of the sample surface corresponds to the footprint of the multiple beams. The new location may be such that it results in the scanning of an area or portion on the sample adjacent to the area scanned at the previous location of the sample, in order to scan a large, continuous area. That is, the area may be contiguous. (Such an adjacent area of ​​the sample surface may be referred to as the scanned area.) Alternatively, the new location may be such that it results in the scanning of an area on the sample that is separate from the area scanned at the previous location of the sample. The two areas may be spaced apart. Scanning each pitch area (e.g., scanning the sub-beams in the X direction and stepping the sub-beams in the Y direction) involves electrostatically deflecting the sub-beams (e.g., scanning in the X direction and stepping in the Y direction) over a distance substantially equal to the pitch of the sub-beams in the multi-beam.

[0077]

[0099] FIG. 12 illustrates an alternative method, which may be called continuous scanning. As shown, an area of ​​the sample surface is moved under the footprint of the multibeam. In this approach, each subbeam is scanned over a fraction of the subbeam pitch (e.g., sequentially up or down or alternating up and down in the Y direction in the illustrated orientation) while the sample 208 is moved in a direction orthogonal to this scan (left to right in the illustrated orientation, e.g., the X direction), e.g., by the sample support 207. The fraction may be equal to the subbeam pitch divided by the square root of the number of subbeams in the multibeam. (This is appropriate when the array is square, e.g., an N×N array of subbeams. More generally, for an N×M array of subbeams, the fraction is, e.g., the pitch divided by the number of columns of subbeams in the mechanical scan direction.) By arranging the grid positions 702 on a grid with axes aligned obliquely with respect to the movement of the sample 208, it is possible to process successive areas on the sample 208 without having to electrostatically scan individual subbeams over large distances. To process successive areas, the stripes are scanned by different aligned sub-beams. Similar to the configuration of Figure 11, the scan area includes a main scan area 704A and a boundary region 704B to allow for non-uniformity in beam pitch.

[0078]

[0100] Leap scanning methods are not easy to use when electrostatic scanning over large distances is not available. This may be the case in embodiments of the present disclosure where the objective, particularly the objective lens array described with reference to and shown in, for example, Figures 3-5, is close to the sample. In some embodiments, the electrostatic deflection range available for the sub-beams is significantly smaller than the pitch of the sub-beams at the sample surface. For example, a typical range for sub-beam pitch may be 50-500 micrometers (e.g., 70-150 micrometers), and a typical range for electrostatic deflection may be in the range of 0.5-2.0 micrometers.

[0079]

[0101] The continuous scanning method can be used when the available range of electrostatic scanning is limited. However, the scan-in / scan-out inherent in this type of scanning can reduce throughput. The scan-in / scan-out effect occurs because the subbeams in one row jointly process the area between that row and its adjacent row. Therefore, all of the subbeams in the row must be used to process the area between two rows. This means that continuous scanning begins to be fully effective only after the multibeam has scanned a length equal to the size of the multibeam (which may be referred to as the scan-in length). A similar effect occurs at the end of the scan line, which corresponds to the scan-out effect. If a relatively small array of subbeams is used, the scan-in and scan-out effects may be tolerable. For example, if a 5 × 5 array of subbeams with an 8 μm pitch is used, the overall size of the multibeam will be 40 μm. This means that the first 40 μm of continuous scanning cannot be used. However, for many practical implementations of embodiments of the present disclosure, much larger multibeams are desirable, including multibeams with sizes ranging from 1 mm to 15 mm (e.g., approximately 4 mm or 10.5 mm). For such dimensions, if a 10 mm x 10 mm surface area is scanned per sample, the ineffective portion of the processing time can represent up to 100% of the effective portion of the processing time, thereby halving throughput. Other scan-in and scan-out effects may exist within the first and last scanned regions of a scanned area (i.e., among adjacent scanned areas). This is because some rows in a multibeam configuration may be incomplete, and overlapping scans of adjacent areas (i.e., scans of adjacent footprints) may aid in the completion of a particular row. Thus, successive scans only begin to become fully effective with subsequent scans of adjacent areas.

[0080]

[0102] The arrangements described below provide alternative ways of at least partially addressing one or more of the problems discussed above with reference to Figures 11 and 12 or other problems.

[0081]

[0103] FIG. 13 illustrates a framework for a method of processing a sample 208 using multiple beams of charged particles. Processing may include scanning the multiple beams across the sample 208 and causing charged particles to be emitted from the sample 208. The emitted charged particles may be detected and used to determine information about the sample 208. The method may be implemented using a charged particle tool (which may be referred to as a charged particle system). The charged particle tool may include or consist of a charged particle characterization tool. The charged particle tool includes a stage 209. The stage 209 may take any of the forms described above with reference to FIGS. 1-3. The stage 209 is configured to support the sample 208, for example, using a sample holder 207. The stage 209 may be configured to move and step the sample 208 in different directions. Moving the stage within the paths of the sub-beams may be referred to as scanning the sub-beams and the sample relative to each other. The sample 208 has a sample surface. The charged particle tool includes a column. The column directs the multiple sub-beams of charged particles onto the sample surface. The column may be configured to direct and deflect (i.e., adjust the direction of the paths of the sub-beams) toward the sample. Such movement of the column relative to the beam of sub-beams may be referred to as scanning the sub-beams and the sample relative to each other. Thus, scanning of the sub-beams relative to the sample may be induced by movement of the column relative to the sub-beams and / or movement of a stage relative to the position of the sample relative to the paths of the sub-beams. Thus, the column may be configured to direct and scan the multiple sub-beams. The multiple sub-beams may be referred to as an array of sub-beams. The column may direct the multiple sub-beams onto a portion of the sample surface, a portion of which may be assigned to each sub-beam. The stage 209 and the column are controlled so that the portion is scanned by the sub-beams. The column may include or consist of any of the electron-optical systems described above with reference to FIGS. 1-10.

[0082]

[0104] The tool is configured to control the stage 209 and column to perform steps S1-S5 in sequence (i.e., S1, then S2, then S3, then S4, then S5). The stage 209 and column may be controlled by a controller 50, for example, as described above with reference to FIG. 1. The controller 50 may include any suitable combination of data processing hardware, firmware, software, and / or computer-controlled actuators, sensors, etc., necessary to provide the desired functionality. The controller may be configured to control the column to scan and to control the stage 209 to move and step.

[0083]

[0105] In step S1, as illustrated in FIG. 14 for a single exemplary sub-beam of the multi-beam, the stage 209 is used to move the sample 208 in a direction parallel to a first direction (e.g., along one of the horizontal paths 721 shown in FIG. 14 ) while the column is used to repeatedly scan the multi-beam across the sample surface in a direction parallel to a second direction (e.g., along the vertical path 722 shown in FIG. 14 ). The column may include, for example, an electrostatic deflector configured to perform scanning of the multi-beam across the sample in step S1. The deflector may take any of the forms described above with reference to FIGS. 3-10 . The deflector may be implemented as a macro-scanning deflector 265 as illustrated in FIG. 3 or a scanning deflector array, such that an elongated region 724 on the sample surface is processed with each sub-beam. Thus, the controller may be configured to repeatedly scan the sub-beams (e.g., by the column) across the sample surface in different directions while moving the sample surface (e.g., using the stage 209) in one direction relative to the array of sub-beams. This processes elongated regions of each sub-beam processing area (see below). For example, in the configuration of FIG. 14, this operation may process the topmost elongated region 724 with the sub-beam corresponding to the region shown in FIG. 14. Paths 721 and 722 and elongated region 724 are shown schematically for visibility in the drawing. In reality, paths 721 and 722 would be closer together, and many more elongated regions 724 would be processed. The width of elongated region 724, which may be defined by the available range of electrostatic deflection, may typically be in the range of 0.5 to 2.0 micrometers, for example. The length of elongated region 724, which may be defined by the pitch of the sub-beams in the multi-beam, may typically be in the range of 50 to 500 micrometers, for example.

[0084]

[0106] 14, the first and second directions are horizontal and vertical (in the plane of the page). Thus, the first and second directions are perpendicular to each other in this example. Thus, the movement of the sample surface relative to the array of sub-beams, which may be continuous (e.g., along path 721), may be in a direction orthogonal to the scanning of the sub-beams. In other embodiments, the first and second directions are oblique to each other.

[0085]

[0107] In step S2, the stage 209 is used to displace the sample 208 in a direction diagonal or perpendicular to the first direction. In the example of FIG. 14 , the sample 208 is displaced in a direction perpendicular to the first direction (e.g., vertically downward in the plane of the page). This displacement of the sample 208 may be referred to as stepping. Accordingly, the stage 209 may be configured to step the sample 208. Thus, the movement of the sample surface relative to the array of sub-beams along path 721 may be in a direction orthogonal to the stepping of the stage 209. For example, after processing the topmost elongated region 724 of FIG. 14 in one iteration of step S1, the stage 209 may align the sub-beams with the next horizontal path 721 to prepare for the next iteration of step S1 (this movement may be referred to as stepping). The step movement of the sub-beams between paths 721 in a direction oblique or perpendicular to the first direction optionally corresponds to a dimension of an elongated region 724 perpendicular to the first direction.

[0086]

[0108] In step S3, steps S1 and S2 are repeated multiple times to further process elongated regions 724 with each sub-beam. Thus, the next iteration of step S1 may process the second-top elongated region 724, and a subsequent iteration of step S1 may process the third-top elongated region 724. The resulting multiple processed elongated regions 724 (which may alternatively be referred to as "processing strips") define sub-beam processing areas 740 (which may alternatively be referred to as "processing areas") for each sub-beam. Thus, the multiple elongated regions 724 together define each sub-beam processing area 740. Each sub-beam processing area is associated with a respective sub-beam. Thus, each step of stage 209 (e.g., in step S2) may include a step relative to elongated region 724 within the sub-beam processing area 740 associated with each sub-beam. Thus, each step is sufficiently small so that each sub-beam remains within the area that will become the sub-beam processing area 740 associated with that sub-beam after each step. Step S2 may optionally be omitted after the last elongated region 724 is formed within the sub-beam processing area 740. In the configuration shown in FIG. 14 , the stepping from one elongated region 724 to the next is performed downward in the orientation of FIG. 14 . In other configurations, the stepping from one elongated region 724 to the next may be performed in the opposite direction (upward in the orientation of FIG. 14 ). Thus, the stage 209 displaces the sample 208 in a stepwise manner in a direction angled (i.e., diagonally or perpendicularly) to the first direction. During the stepping, the stage 209 displaces the sample to move it parallel to the first direction. During the movement of the sample parallel to the first direction, the column repeatedly scans the multibeam across the sample surface in a direction different from the first direction. This repeated scanning is such that, with each step, each sub-beam scans an elongated region of a portion of the sample surface assigned to the sub-beam.

[0087]

[0109] The distance of sample displacement in step S2 after repeating step S1 is such that the processed elongated regions 724 in each sub-beam processing area 740 overlap (as illustrated in FIG. 14) or are adjacent. The distance of sample 208 displacement by stage 209 in a direction diagonal or perpendicular to the first direction during sequential step movements may therefore be less than the maximum range of multi-beam scanning during repeated multi-beam scanning parallel to the second direction. In some embodiments, the elongated regions 724 are configured to overlap by an amount effective to compensate for imperfections such as variations in deflection strength from sub-beam to sub-beam. In some embodiments, for example, the overlap is in the range of 5% to 10% of the width of the elongated regions 724. For a typical deflection range of 1.0 micrometer, this corresponds to an overlap in the range of 50 nm to 100 nm.

[0088]

[0110] Thus, a charged particle tool is provided having a column configured to direct a multi-beam of sub-beams of charged particles onto a sample surface. A portion of the sample surface corresponds to a multi-beam output area (which may alternatively be referred to simply as an "output area") of the column facing the sample surface. The multi-beam output area may correspond to a portion of the column through which the multi-beam passes when output toward the sample 208. The size and shape of the multi-beam output area may be defined by an objective lens array in the column. The size and shape of the multi-beam output surface may be substantially equal to the size and shape of a portion of the objective lens array closest to the sample 208. Thus, the size and shape of a portion of the sample surface may be defined by the objective lens array and / or a portion of the objective lens array closest to the sample 208. The tool is configured to control the stage 209 and the column such that the portion is scanned by the sub-beams of the multi-beam, a portion of the portion assigned to each sub-beam. The scanning may be performed as described above with reference to steps S1-S3. Thus, the stage 209 can displace the sample 208 in successive steps in a direction diagonal or perpendicular to the first direction, and can move the sample 208 in a direction parallel to the first direction in each step such that each sub-beam scans a corresponding portion in the direction parallel to the first direction in each step. The column can repeatedly scan the multiple beams across the sample surface in a direction parallel to the second direction during movement of the sample 208 in the direction parallel to the first direction.

[0089]

[0111] Although the process of steps S1-S3 is shown in FIG. 14 for only a single sub-beam, it is performed in parallel for all of the sub-beams. That is, the process of steps S1-S3 may be performed simultaneously by each sub-beam with its respective sub-beam processing area 740. This is because in step S1, the multi-beam is scanned as a whole. Therefore, the number of sub-beam processing areas 740 will be the same as the number of sub-beams.

[0090]

[0112] In step S4, the stage is used to displace the sample at the sample surface a distance equal to at least twice the pitch of the subbeams in the multibeam. This displacement may be referred to as leap displacement. The displacement distance may be much greater than twice the pitch, and optionally may be as large as the overall size of the multibeam at the sample surface (as discussed in more detail below). The displacement distance may even be comparable to the size of the sample (e.g., a wafer). The different multibeam size areas need not be adjacent. This may be desirable in some applications (e.g., to scan a large, continuous area). In other applications, it may be desirable to scan different areas of the sample. Thus, the sample is moved such that a new area of ​​the sample surface moves under the multibeam output area of ​​the column. Typically, the movement relative to the adjacent new area is in either a first direction or a second direction. However, the movement may be in any direction to any area of ​​the sample surface.

[0091]

[0113] In step S5, after the displacement in step S4, steps S1 to S4 are repeated from a new location on the sample. Thus, the multi-beam may be scanned multiple times with sequential step movements (e.g., steps S1 to S3) to form multiple corresponding sub-beam processing areas with each sub-beam, and after each sequential step movement, stage 209 may perform leap displacement (e.g., step S4).

[0092]

[0114] In some embodiments, the maximum range of scanning of the multibeam by the column in step S1 (e.g., during repeated scanning of the multibeam by the column in a direction parallel to the second direction) is less than the minimum pitch of the subbeams in the multibeam at the sample surface, and is optionally less than 50%, optionally less than 10%, optionally less than 5%, optionally less than 2%, optionally less than 1%, or optionally less than 0.5%. As described above with reference to FIGS. 11 and 12 , the subbeams in the multibeam may be provided in a grid defined by grid positions 702. The pitch of the subbeams may refer to the pitch of the grid positions 702. The pitch along different principal axes of the grid may be different. The minimum pitch may be the pitch along the principal axis having the smallest pitch. Unlike the configuration described above with reference to FIG. 11 (referred to as the leap scanning method), this embodiment may therefore be applied when the maximum range of scanning is smaller than the pitch of the subbeams. Therefore, this approach may be applied to embodiments having an objective lens array assembly such as those described above with reference to FIGS. 1-10 .

[0093]

[0115] In some embodiments, each performance of steps S1-S3 defines at least one group of overlapping or adjacent sub-beam processing areas 740 relative to one another, thereby processing a contiguous region larger than any individual sub-beam processing area 740. In one embodiment, this is achieved by configuring the distance of sample movement in step S1 to be substantially equal to the pitch of the sub-beams in the multi-beam on the sample surface in the first direction. Thus, the distance of movement of sample 208 in each step movement in a direction parallel to the first direction may be substantially equal to the pitch of the sub-beams in the multi-beam on the sample surface in the first direction. Thus, sub-beam processing areas 740 formed simultaneously by adjacent sub-beams overlap or are adjacent to one another.

[0094]

[0116] 15 and 16 show an example relationship between the geometry of the sub-beam grid in a multi-beam system (defined by sub-beam grid positions 702) and the geometry of the sub-beam processing area 740 obtained by implementing the method of FIG. 13 . This example illustrates that the symmetry of the sub-beam grid need not be the same as the symmetry of the sub-beam processing area 740. In the illustrated example, the sub-beams are arranged on a hexagonal grid (i.e., a grid with hexagonal symmetry), while the sub-beam processing area 740 is rectangular. By configuring the distance 711 of movement of the sample 208 in step S1 to be equal to the pitch 711 of the sub-beam grid in the first direction (i.e., the width of the hexagons centered on the grid positions 702), continuous coverage of the sample surface parallel to the first direction (horizontally in the illustrated orientation) is achieved. Thus, the length of the elongated region and / or the length of the sub-beam processing area associated with each sub-beam may be equal to the pitch 711. Continuous coverage of the sample surface parallel to the second direction (perpendicular in the illustrated orientation) is achieved by configuring the cumulative distance 712 of the displacement in step S2 (e.g., the step movement of the path 724 on the processing area of ​​the sample surface, performed in a direction parallel to the second direction in this example) to be equal to the pitch 712 of the sub-beam grid in the second direction. That is, the pitch of the sub-beam grid in the second direction may be equal to the cumulative distance of the width of the elongated regions parallel to the direction of the displacement in step S2, e.g., the second direction. The pitch of the sub-beam grid may be determined, for example, by the number of elongated regions on the processing area for each sub-beam, taking into account, for example, the width of the elongated regions in the second direction. The number of elongated regions on the processing area of ​​the sub-beam may be one more than the number of steps of the path 724 on the processing area of ​​the sample surface.

[0095]

[0117] In a specific example where the sub-beams are provided in a hexagonal array with a pitch of 70 micrometers, each sub-beam is scanned across a 70 μm × 60.6 μm rectangular area (defining the sub-beam processing area 740) to scan successive areas (where 60.6 results from 0.5 × √3 × 70 = 60.6). In an exemplary case where the field of view of the objective lens is 1 micrometer, 60 scans of elongated regions 724, each 1.01 μm wide and 70 μm long, are required to cover one 70 μm × 60.6 μm area. Thus, the sub-beam processing area of ​​the surface associated with a sub-beam, e.g., a rectangular area, has a dimension in the second direction equal to the cumulative distance of the widths of the elongated regions over the processing area of ​​the sub-beam in the direction of step movement in step S2, e.g., the second direction. Note that in different configurations, the sub-beams can be provided in an array having a grid of different shapes, e.g., parallelograms, diamonds, rectangles, or squares. For each shape of beam configuration, the sub-beam processing area 740 may be rectangular.

[0096]

[0118] In some embodiments, the displacement of the sample in step S2 is parallel to the second direction (ie, parallel to the direction of scanning of the multibeam across the sample in step S1).

[0097]

[0119] In some embodiments, the paths 722 of the multi-beam scans across the sample 208 by the columns in step S1 are all in the same direction, as illustrated in FIG. 14 (i.e., the scans of the multi-beams across the sample surface in a direction parallel to the second direction while the sample is moving in a direction parallel to the first direction may all be performed in the same direction). In such a configuration, the direction of the scan paths 722 can be said to be stepped. This approach can promote uniformity of the scanning process from one scan to the next and / or allow errors to be corrected more easily. For example, if the scans by the columns in S1 are all performed in the same direction (i.e., stepped), misalignment of the deflector and the detector can result in a shift in the pattern. Such a shift can be corrected in downstream processing of the image. However, if the scans by the columns in S1 are performed in alternating directions, misalignment of the deflector and the detector can result in blurring of the pattern (as alternating pixel columns in the image shift up or down). This blurring is more difficult to correct. In another embodiment, as illustrated in Figure 17, the scanning of the multi-beams through the columns across the sample 209 in step S1 is performed in alternating directions (e.g., in an up-down-up-down-up order in the orientation shown in Figure 17). In such a configuration, the direction of the scan path 722 is continuous and can be said to be serpentine. Configuring the scan path 722 to be continuous can reduce bandwidth requirements compared to a step-and-move approach.

[0098]

[0120] In some embodiments, as illustrated in FIG. 14 , the movement of the sample 208 in step S1 during the repetition of steps S1 and S2 is performed in alternating directions (e.g., such that the path 721 follows a right-left-right-left-right order in the orientation shown in FIG. 14 ). In such a configuration, the direction of the continuous path 721 can be described as continuous and serpentine. This approach minimizes the overall distance traveled by the sample 208. In other embodiments, as illustrated in FIG. 18 , the movement of the sample 208 in step S1 during the repetition of steps S1 and S2 is all in the same direction, for example, across the sub-beam pitch processed area 740. In such a configuration, the direction of the continuous path 721 can be described as stepped.

[0099]

[0121] In some embodiments, as illustrated in FIG. 19 , for example, stage 209 as depicted in FIG. 2 includes independently actuable long-stroke stage 209A and short-stroke stage 209B. The maximum range of motion of long-stroke stage 209A is longer than the maximum range of motion of short-stroke stage 209B. In some embodiments, short-stroke stage 209B is supported by long-stroke stage 209A. Movement of long-stroke stage 209A results in corresponding movement of short-stroke stage 209B without any actuation of short-stroke stage 209B. Long-stroke stage 209A can be configured to provide relatively coarse position control over a relatively long distance. Short-stroke stage 209B can be configured to provide fine position control over a shorter distance. In one embodiment, the range of motion provided by the short-stroke stage can be 1 mm or less, i.e., a displacement of 0.5 mm or less in magnitude relative to the position of the long-stroke stage.

[0100]

[0122] In some embodiments, movement of the sample 208 in steps S1-S3 (e.g., during multi-beam scanning with sequential step movements) is performed exclusively using the short-stroke stage 209B. Thus, the long-stroke stage 209A may remain in the same position and / or may not be actuated while all of the elongated regions 724 defining the multi-beam sub-beam processing areas 740 are formed in a single execution of steps S1-S3. This approach ensures accurate and repeatable sample movement when exclusively using short strokes for movement during scanning, thereby ensuring that the sub-beam processing areas 740 are accurately processed.

[0101]

[0123] In some embodiments, movement of the sample 208 in step S4 (e.g., during each leap displacement) is preferably performed exclusively using the long-stroke stage 209B. Such movement can be achieved rapidly without interfering with the relative positioning of the short strokes with respect to the long strokes. In other embodiments, during a leap displacement by a long stroke, the short strokes also move the sample, so that scanning of the multi-beam with sequential step movements can be resumed on a new portion of the sample, i.e., after the leap displacement. Beneficially, movement can be resumed at a new position to begin processing a new portion of the sample without involving the short strokes in positioning the sample surface relative to the beam path.

[0102]

[0124] In some embodiments, the displacement of the sample in step S4 (e.g., during each leap displacement) is relative to a facing surface of the electron-optical column intended to face the sample, e.g., a detector. Such a facing surface may face any feature of the stage oriented and configured on the stage to be exposed to the beam during operation, such as a surface of the stage away from the sample and an electron-optical sensor. Such a detector of the column may be the element of the electron-optical column positioned closest to the sample during use. The sample-facing surfaces of the column and sample may be positioned close to each other during processing to optimize detector performance. The sample may be positioned relative to the column to optimize sub-beam parameters, such as focus. In the following description, sample positioning is used, but this should also be interpreted as movement of at least the facing surface of the column, since the detector may be operable. At least as far as operable detectors are concerned, see 2019P00407EP02, incorporated herein by reference.

[0103]

[0125] In some embodiments, the sample displacement in step S4 (e.g., during each leap displacement) is performed with the sample positioned further away from the column than during the sample displacement in steps S1-S3 (e.g., during the sequential step-motion scanning of the multibeam). This can be achieved, for example, by using the stage 209 to move the sample 208 away from the column (e.g., by lowering the sample 208) and / or by using the column to move a portion of the column, e.g., a detector, away from the sample 208 (e.g., by raising the detector). In other words, the gap between the sample and the column can be reduced by lowering at least an element of the column, e.g., a detector, during the leap displacement, e.g., by raising the sample. Thus, a relative movement is effected between the sample 208 and the column, increasing the distance between them. The relative movement can be perpendicular and / or parallel to the electron-optical axis of the column. The relative movement can be performed before and / or after the sample displacement in step S4. Thus, moving the sample 208 through a sequence of leap displacements may include relatively displacing the sample along the beam path. Specifically, the relative displacement of the sample along the beam path may include increasing the distance between the sample and the column before moving the sample with the leap displacements. The relative displacement of the sample 208 along the beam path may further include decreasing the distance between the sample 208 and the column after moving the sample with the leap displacements.

[0104]

[0126] By performing the sample displacement in step S4 with the sample positioned further away from the column than during the sample movement in steps S1-S3, the risk of collision between the sample 208 and the column, particularly the portion of the column proximate to the sample, is reduced. This approach can reduce the risk of collision with elements of the column that may be proximate to the sample during operation, such as the column's detector. The detector may be configured to detect charged particles emitted from the sample 208 and may need to be positioned relatively close to the sample 208, e.g., facing the surface, during scanning of the sub-beams across the sample surface. The detector may, for example, be as described with reference to and shown in Figures 7-10. The distance between the sample and the facing surface of the column may be less than 300 micrometers, less than 200 micrometers, less than 100 micrometers, 50-5 micrometers, or 30-10 micrometers. The distance between the sample and the facing surface of the column during the sample displacement in step S4 may, for example, be between 1 mm and 100 micrometers during leap displacement. Such a reduced risk of collision may be beneficial during the relatively long movements occurring in step S4, and / or to reduce the need for sophisticated sensor systems, for example to detect the relative position of the sample with respect to portions of the column adjacent to the sample, and / or to reduce the need for control techniques to reduce the risk of collision during such long movements of the sample, which may be between 1 mm and 300 mm.

[0105]

[0127] As illustrated in FIG. 20 , the column footprint 732 may be defined as the smallest bounding box on the sample surface that encloses all of the sub-beam processing areas. Thus, the footprint 732 has a contour or boundary that corresponds to (e.g., is the same as) the contour of the smallest bounding box on the sample surface that encloses all of the sub-beam processing areas. The sub-beam processing area enclosed by the smallest bounding box is the sub-beam processing area formed at a single position of the sample (which may be referred to as a single nominal processing position) during leap displacement. The single position may correspond to a single position of the long-stroke stage 209A. The single position may correspond to a single execution of multi-beam scanning (e.g., relative to one position of the long-stroke stage 209A) from a single execution of steps S1-S3 with sequential step movements. Thus, in a configuration that includes steps S1-S3, the column footprint 732 may be defined to have a contour that corresponds to the contour of the smallest bounding box on the sample surface that encloses all of the sub-beam processing areas from a single execution of steps S1-S3. The size and shape of the column's footprint may be defined by the size and shape of the column's multibeam output surface (e.g., the portion of the objective lens array closest to the sample 208). In some embodiments, the distance of displacement of the sample 208 in step S4 (schematically indicated by arrow 734 from the center 730 of one footprint 732 to the center 730 of another footprint 732) is substantially equal to or greater than a dimension 735 of the footprint parallel to the direction of displacement. The direction of displacement in step S4 may be parallel to a first direction (corresponding to the direction of displacement of the sample 208 in step S1), or parallel to a second direction (corresponding to the expected direction of displacement of the sample 208 in step S2), or may be a different direction as illustrated in FIG. 20.

[0106]

[0128] In some embodiments, as illustrated in Figures 21-23, performances of steps S1-S3 (e.g., each performance of scanning the multi-beam in sequential step movements) define multiple groups of sub-beam processing areas. Each group of sub-beam processing areas may be located in a corresponding portion of footprint 732. Such group locations 241A-F (hereinafter referred to as "group locations" 241A-F) are shown schematically as solid hexagons in Figures 21-23.

[0107]

[0129] Each filled hexagon represents an area corresponding to a single subbeam (on a hexagonal grid). The hexagonal shape is hexagonal due to the symmetry of the multibeam. Each hexagon represents a portion of the multibeam whose subbeams are assigned to a single subbeam (which may be called an array of subbeams).

[0108]

[0130] For multi-beams with different symmetries, tiling shapes other than hexagons may be appropriate. As discussed above with reference to Figures 15 and 16, the sub-beam processing areas at these group locations are typically square or rectangular due to the way the sub-beams are scanned across the sample. Thus, the shape of the sub-beam processing areas may differ from the shape of the portion of the multi-beam assigned to each sub-beam. The area of ​​the sub-beam processing area associated with each sub-beam may be equal to the area of ​​the portion of the multi-beam assigned to the sub-beam.

[0109]

[0131] The unfilled hexagons in Figures 21 and 22 represent areas where no subbeams are present. Such areas of the footprint corresponding to the unfilled hexagons or cells may be referred to as untreated footprint portions. Such unfilled footprint portions may extend across the footprint in a direction, for example, from one side of the footprint to the other. This may be desirable, for example, to allow space for thermal conditioning, e.g., cooling, of structures in the columns or other features (e.g., spacers to improve mechanical rigidity and / or data signal lines and / or power supply lines to or from detectors or electro-optical elements). For an array of apertures incorporating thermal conditioning structures, see European Patent No. 2638560, published September 18, 2013, which is incorporated herein by reference.

[0110]

[0132] When steps S1-S3 are performed, sub-beam processing areas are defined in regions on the sample surface corresponding to the filled hexagons. Thus, each group of sub-beam processing areas is represented by a contiguous group of filled hexagons (although the sub-beam processing areas themselves are typically square or rectangular). The sub-beam processing areas within each group overlap or are adjacent to each other and are separated from the sub-beam processing areas of other groups. Thus, the sub-beam processing areas in each group are interconnected and may be referred to as interconnected or adjacent sub-beam processing areas (or "interconnected areas"). The groups are separated from each other. Thus, the sub-beam processing areas in each group are separated (not interconnected) from the sub-beam processing areas of each of the other groups. In the illustrated example, for each performance of steps S1-S3, three groups exist in three corresponding regions (241A-C in FIG. 21 and 241D-F in FIG. 22).

[0111]

[0133] The displacement (e.g., leap displacement) of the sample in step S4 is such that a group of sub-beam processing areas from one implementation of steps S1-S3 (e.g., scanning a multi-beam in sequential step movements) is positioned relative to a group of sub-beam processing areas from another implementation of steps S1-S3 to form at least one contiguous enlarged group of sub-beam processing areas. The enlarged group includes two or more groups of sub-beam processing areas. This can be achieved, for example, by configuring the displacement of sample 208 in step S4 such that an enlarged group is formed by interleaving groups generated from different implementations of steps S1-S3, as shown in FIGS. 21-23.

[0112]

[0134] In the illustrated example, a first execution of steps S1-S3 forms three groups of sub-beam processing areas. The three groups are located at group locations 241A-C, as shown in FIG. 21 . The sample 208 is then moved, e.g., stepped (e.g., a further leap displacement), to a new position in step S4. This movement results in a second execution of steps S1-S3, defining further sub-beam processing areas at different group locations 241D-F on the sample surface, as shown in FIG. 22 . Thus, each execution of steps S1-S3 is performed with the stage at a different nominal processing position. This may be achieved by the stage performing a series of leap displacements to move the sample 208 relative to the column through a corresponding sequence of nominal processing positions (which may be referred to simply as processing positions, although several small stage movements may occur at each such processing position, as described below).

[0113]

[0135] At each nominal processing position, the multi-beam is scanned across the sample surface, with each sub-beam processing a sub-beam processing area. The resulting sub-beam processing areas include multiple groups of interconnected sub-beam processing areas (which may be referred to as adjacent sub-beam processing areas). The groups are separated from one another. While the stage is at the nominal processing position, small movements of the stage (e.g., the small movements described above with reference to steps S1-S3) may occur.

[0114]

[0136] Each leap displacement is longer than any of the small movements made at each nominal processing position, typically many times longer. The leap displacement is equal to or greater than twice the pitch of the multi-beam beam at the sample surface, and optionally many times longer. In practice, there are embodiments in which the leap displacement is many times longer, e.g., 10 to 100 times the pitch. Corresponding adjacent regions of interconnected sub-beam processing areas can be as wide as the corresponding number of columns of sub-beam processing areas, e.g., 10 to 100 columns. As noted above, in some configurations, the leap displacement is 1 mm to 300 mm. The leap displacement can typically be near the lower end of the range in configurations in which interleaving is used, e.g., about 10 times the beam pitch. When interleaving is not used, the leap displacement can also be near the lower end of the range, but can be larger.

[0115]

[0137] In some configurations, the nominal processing locations are such that at least one of the groups of interconnected sub-beam processing areas formed at one of the nominal processing locations is interleaved between at least two of the groups of interconnected sub-beam processing areas formed at a different one of the nominal processing locations. This is illustrated in Figures 21-23 and described in more detail below with reference to the case where steps S1-S3 are performed at each of the nominal processing locations. In other configurations, steps other than steps S1-S3 may be used to generate the groups of interconnected sub-beam processing areas at each of the nominal processing locations.

[0116]

[0138] In the example of Figures 21-23, group locations 241A-C shown in Figure 21 are displaced relative to group locations 241D-F shown in Figure 22 to achieve interleaving. In this example, the cumulative effect of two runs of steps S1-S3 results in groups of sub-beam processing areas being defined as shown in Figure 23. (Note that in Figure 23, the first run is lower, e.g., the sample movement between the two runs is displaced in an orthogonal direction by two grid cells. This detail is not necessary and is merely included so that the different group locations of each run can be recognized.) Thus, groups of sub-beam processing areas are combined in this way to form an expanded group of sub-beam processing areas. The sub-beam processing areas in the expanded group are interconnected and include at least one interleaved group. The enlarged groups of sub-beam processing areas (e.g., formed by interleaving smaller groups of sub-beam processing areas) allow continuous coverage of larger areas of the sample surface even where features, such as cooling configurations, are provided that correspondingly prevent complete coverage of the processing area by the sub-beams of the multi-beam. To allow for interleaving, the widths of the groups of sub-beam processing areas can be similar to the separation width between the groups. Thus, the groups of sub-beam processing areas and the surface of the sample corresponding to the unprocessed footprint portions can have similar widths, e.g., more than twice the width of the sub-beam processing areas. Thus, groups of sub-beam processing areas can be mapped onto previously unprocessed footprint portions, interleaving the groups of sub-beam processing areas and allowing continuous coverage of the sample surface. Thus, the combined width of the unprocessed footprint portions can account for up to 50 percent of the footprint width. In embodiments involving such interleaving, the distance of the sample displacement in the leap displacement (e.g., in step S4) will be less than (smaller than) the footprint dimension parallel to the direction of movement (e.g., in contrast to the situation described above with reference to FIG. 20 ). Such a footprint may therefore have a width that is six or more times the pitch of the sub-beam processing areas.With this configuration, there will be two groups on either side of the untreated portion. In different configurations, the footprint can be sized to have a desired number of groups and a pitch of a desired number of sub-beam treatment areas. The number of untreated footprint portions can correspond to the number of groups or one less.

[0117]

[0139] Thus, an array of sub-beams, e.g., a multibeam, may have, for example, two dimensions in which the sub-beams are organized. In one of the array dimensions, the array includes at least three, preferably at least four, sub-beams. The at least four sub-beams are included in at least two groups and at least one unprocessed portion (or unprocessed footprint portion). The unprocessed portions are each between or interleaved between two of the groups. The groups and unprocessed portions extend across the array and in the other dimension of the array, e.g., with a dimension several times larger than the pitch of the sub-beams, e.g., 2, 3, 5, 10, 50, 100 or more times larger.

[0118]

[0140] Embodiments of the present disclosure are defined in the following numbered clauses: Clause 1. A charged particle tool (or charged particle system) comprising: a stage for supporting a sample having a sample surface; and a column configured to direct multiple sub-beams of charged particles onto the sample surface, the charged particle tool (or charged particle system) being configured to control the stage and column to sequentially: (a) use the stage to move the sample in a direction parallel to a first direction while using the column to repeatedly scan the multiple beams across the sample surface in a direction parallel to a second direction, thereby processing an elongated region on the sample surface with each sub-beam; (b) use the stage to displace the sample in a direction oblique or perpendicular to the first direction; and (c) repeat (a) and (b) multiple times to process further elongated regions with each sub-beam, the resulting multiple processed elongated regions defining a sub-beam processing area for each sub-beam.

[0119] A tool (or system) according to clause 1, wherein the maximum range of scanning of the multi-beam by the column in clause 2(a) is smaller than the minimum pitch of the sub-beams in the multi-beam on the sample surface.

[0120] A tool (or system) according to clause 1 or 2, wherein the distance of displacement of the sample in clause 3(b) is such that the multiple processed elongated regions in each sub-beam processing area partially overlap or are adjacent.

[0121] A tool (or system) according to any one of clauses 1 to 3, wherein the distance of movement of the sample in clause 4.(a) is substantially equal to the pitch of the sub-beams in the multi-beam in the first direction on the sample surface.

[0122] A tool (or system) according to any one of clauses 1 to 4, wherein the implementation of clause 5.(a) to (c) defines at least one group of sub-beam processing areas that are partially overlapping or adjacent to each other.

[0123] The tool (or system) of any one of the preceding clauses, wherein the displacement of the sample in clause 6.(b) is parallel to the second direction.

[0124] A tool (or system) according to any one of the preceding clauses, configured so that the scanning of the multiple beams over the sample by the columns in clause 7.(a) is all performed in the same direction.

[0125] A tool according to any one of clauses 1 to 6, configured such that scanning of the multi-beams over the sample by the columns in clause 8.(a) is performed in alternating directions.

[0126] Clause 9. A tool (or system) according to any one of the preceding clauses, configured such that movement of the sample in (a) during the repetition of (a) and (b) is in alternating directions.

[0127] Clause 10. A tool (or system) according to any one of clauses 1 to 8, configured so that the movement of the sample in (a) during the repetitions of (a) and (b) is all in the same direction.

[0128] Clause 11. A tool (or system) described in any one of the preceding clauses, further configured to control the stage and column to sequentially perform, after steps (a) to (c), (d) using the stage to displace the sample by a distance equal to at least twice the pitch of the sub-beams in the multi-beam at the sample surface, and (e) repeating (a) to (d).

[0129] Clause 12. A tool (or system) as described in clause 11, wherein the stages include independently actuable long-stroke and short-stroke stages, the maximum range of motion of the long-stroke stage being greater than the maximum range of motion of the short-stroke stage.

[0130] Clause 13. In (a) to (c), a tool (or system) according to clause 12, configured to move the sample preferably exclusively using a short stroke stage.

[0131] In clause 14.(d), a tool (or system) according to clause 12 or 13, configured to move the sample preferably exclusively using a long stroke stage.

[0132] Clause 15. A tool (or system) according to any one of clauses 11 to 14, configured such that the displacement of the sample in (d) is carried out with the sample positioned further away from the column than during the movement of the sample in (a) to (c).

[0133] Clause 16. A tool (or system) described in any one of clauses 11 to 15, wherein the column footprint is defined as the smallest bounding box on the sample surface that encloses all of the sub-beam processing areas from implementation of (a) to (c), and the distance of sample displacement in (d) is substantially equal to or greater than the dimension of the footprint parallel to the direction of movement.

[0134] A tool (or system) described in any one of clauses 11 to 16, wherein the implementation of clause 17.(a) to (c) defines multiple groups of sub-beam processing areas, the sub-beam processing areas within each group being partially overlapping or adjacent to each other and separated from the sub-beam processing areas of other groups.

[0135] The tool (or system) described in Clause 17, wherein the displacement of the sample in Clause 18.(d) is such that a group of sub-beam processing areas from one implementation of (a)-(c) is positioned relative to a group of sub-beam processing areas from another implementation of (a)-(c) to form at least one enlarged group of sub-beam processing areas comprising two or more groups of sub-beam processing areas.

[0136] Clause 19. The tool (or system) of clause 18, wherein the displacement of samples in (d) is performed such that an enlarged group is formed by interleaving groups from different implementations of (a) to (c).

[0137] Clause 20. A tool (or system) according to any one of clauses 17 to 19, wherein the column footprint is defined as the smallest bounding box on the sample surface that encloses all of the sub-beam processing areas from implementation of (a) to (c), and the distance of sample displacement in (d) is less than the dimension of the footprint parallel to the direction of movement.

[0138] Clause 21. A tool (or system) described in any one of clauses 11 to 20, comprising a controller configured to control the stage and column and optionally the electrostatic deflector to perform (a) to (e).

[0139] Clause 22. A tool (or system) according to any one of the preceding clauses, further comprising a detector configured to detect charged particles emitted from the sample.

[0140] Clause 23. A tool (or system) according to any one of the preceding clauses, wherein the column comprises an electrostatic deflector configured to perform a scan of the multi-beam across the sample in (a).

[0141] Clause 24. A charged particle tool (or charged particle system), comprising: a stage for supporting a sample having a sample surface; and a column configured to direct a multi-beam of sub-beams of charged particles onto the sample surface, a portion of the sample surface corresponding to a multi-beam output area of ​​the column facing the sample surface; the tool configured to control the stage and the column such that the portion is scanned by the sub-beams of the multi-beam, a portion of the portion being assigned to each sub-beam; the stage configured to displace the sample in successive step movements in a direction oblique or perpendicular to a first direction, and in each step to move the sample in a direction parallel to the first direction such that in each step each sub-beam scans a corresponding portion in the direction parallel to the first direction; and the column configured to repeatedly scan the multi-beams across the sample surface in a direction parallel to the second direction during movement of the sample in the direction parallel to the first direction.

[0142]

[0141] Clause 25. A charged particle system comprising: a stage configured to support a sample having a sample surface and to move and step in different directions; a column configured to direct an array of sub-beams of charged particles onto the sample surface and to scan them across the sample surface, wherein a sub-beam processing area of ​​the sample surface is associated with each sub-beam of the array of sub-beams; and a controller configured to control the column to scan and to control the stage to move and step, wherein the charged particle system is configured to repeatedly scan the sub-beams in different directions across the sample surface while moving the sample surface in a direction relative to the array of sub-beams, thereby processing elongated regions of the sub-beam processing area associated with each sub-beam, and to step the stage relative to the elongated regions within the sub-beam processing area.

[0143]

[0142] Clause 26. The system of clause 25, further configured to further process elongated regions of the sub-beam processing area.

[0144]

[0143] Clause 27. The system of clause 26, configured to further process the elongated regions to define sub-beam processing areas for each sub-beam.

[0145]

[0144] Clause 28. A system according to any one of clauses 25 to 27, wherein the length of the sub-beam processing area associated with each sub-beam is equal to the pitch of the sub-beams in the array of sub-beams at the sample surface.

[0146]

[0145] Clause 29. A system according to any one of clauses 25 to 28, wherein the length of the elongated region is equal to the pitch of the sub-beams in the array of sub-beams at the sample surface.

[0147]

[0146] Clause 30. A system according to any one of clauses 25 to 29, wherein the area of ​​the sub-beam processing area associated with each sub-beam is equal to the area of ​​the portion of the array allocated to the sub-beam.

[0148]

[0147] Clause 31. A system according to clause 30, wherein the shape of the sub-beam processing area is different from the shape of a portion thereof.

[0149]

[0148] Clause 32. A system according to any one of clauses 25 to 31, configured so that the movement of the sample surface relative to the array of sub-beams is continuous.

[0150]

[0149] Clause 33. A system according to any one of clauses 25 to 32, configured such that movement of the sample surface relative to the array of sub-beams is in a direction orthogonal to the scanning of the sub-beams.

[0151]

[0150] Clause 34. A system according to any one of clauses 25 to 33, configured such that movement of the sample surface relative to the array of sub-beams is in a direction orthogonal to the step movement of the stage.

[0152]

[0151] Clause 35. A charged particle system comprising: a stage for supporting a sample having a sample surface; and a column configured to direct a multi-beam of sub-beams of charged particles onto the sample surface, a portion of the sample surface corresponding to a multi-beam output area of ​​the column facing the sample surface, the system being configured to control the stage and column so that the portion is scanned by the sub-beams of the multi-beam, a portion of the portion being assigned to each sub-beam, the system being configured to control the stage to move the sample in a direction parallel to the first direction in each step to displace the sample in successive step movements in a direction oblique or perpendicular to a first direction, and so that in each step each sub-beam scans a corresponding portion in the direction parallel to the first direction, and the system being configured to control the column to repeatedly scan the multi-beams over the sample surface in a direction parallel to the second direction during movement of the sample in the direction parallel to the first direction.

[0153]

[0152] Clause 36. A system as described in clause 35, wherein the maximum range of scanning of the multibeam by the column during repeated scanning of the multibeam by the column in a direction parallel to the second direction is smaller than the minimum pitch of the sub-beams in the multibeam on the sample surface.

[0154]

[0153] Clause 37. A system as described in Clause 36, configured so that the distance of displacement of the sample by the stage in a direction diagonal or perpendicular to the first direction at each successive step movement is less than the maximum range of scanning of the multi-beam by the column during repeated scanning of the multi-beam by the column in a direction parallel to the second direction.

[0155]

[0154] Clause 38. A system described in any one of clauses 35 to 37, configured so that the distance of movement of the sample in a direction parallel to the first direction in each step movement is substantially equal to the pitch of the sub-beams in the multi-beam in the first direction on the sample surface.

[0156]

[0155] Clause 39. A system described in any one of clauses 35 to 38, configured so that scanning of multiple beams across the sample surface in a direction parallel to a second direction while moving the sample in a direction parallel to a first direction is all performed in the same direction.

[0157]

[0156] Clause 40. A system according to any one of clauses 35 to 39, configured to scan the multiple beams in sequential step movements so that a sub-beam treatment area is treated by each sub-beam.

[0158]

[0157] Clause 41. A system as described in Clause 40, configured to perform multiple scans of the multi-beam with sequential step movements to form corresponding multiple sub-beam processing areas with each sub-beam, and preferably to perform a leap displacement after each scan of the multi-beam with sequential step movements, the leap displacement including displacing the sample by a distance equal to at least twice the pitch of the sub-beams in the multi-beam on the sample surface.

[0159]

[0158] Clause 42. A system as described in Clause 41, wherein the stage comprises a long stroke stage and a short stroke stage which are independently operable, the maximum range of motion of the long stroke stage being longer than the maximum range of motion of the short stroke stage, the system being configured to move the sample exclusively using the short stroke stage during scanning of the multi-beam in sequential step movements, and the system being configured to move the sample preferably exclusively using the long stroke stage during each leap displacement.

[0160]

[0159] Clause 43. A system as described in clause 42, configured such that movement of the sample during leap displacement is performed with the sample positioned further away from the column than during scanning of the multi-beam with sequential step movements.

[0161]

[0160] Clause 44. A system described in any one of clauses 41 to 43, wherein the column footprint is defined as the smallest bounding box on the sample surface that encloses all of the sub-beam processing areas from a single execution of a multi-beam scan with sequential step movements, and preferably the distance of each leap displacement is substantially equal to or greater than the dimension of the footprint parallel to the direction of displacement.

[0162]

[0161] Clause 45. A system described in any one of clauses 41 to 43, wherein each execution of scanning the multi-beam with sequential step movements defines multiple groups of sub-beam processing areas, the sub-beam processing areas within each group being partially overlapping or adjacent to each other and separated from the sub-beam processing areas of other groups.

[0163]

[0162] Clause 46. A system as described in Clause 45, wherein at least one of the leap displacements is such that a group of sub-beam processing areas from one performance of scanning the multi-beam with sequential step movements is positioned relative to a group of sub-beam processing areas from another performance of scanning the multi-beam with sequential step movements to form at least one enlarged group of sub-beam processing areas comprising two or more groups of sub-beam processing areas.

[0164]

[0163] Clause 47. A system as described in clause 46, wherein at least one of the leap displacements is such that an enlarged group is formed by interleaving groups from different implementations of multi-beam scanning with sequential step movements.

[0165]

[0164] Clause 48. A charged particle system comprising: a stage configured to support and move a sample having a sample surface; a column configured to direct an array of sub-beams of charged particles onto the sample surface and scan them across the sample surface; and a controller configured to control the stage and column to: (a) move the sample surface in one direction relative to the array of sub-beams while repeatedly scanning the sub-beams in different directions across the sample surface, thereby treating an elongated region on the sample surface with each sub-beam; (b) displace the stage relative to an elongated region within a sub-beam treatment area of ​​the sample surface associated with each sub-beam; and (c) repeat steps (a) and (b) to treat a plurality of elongated regions with each sub-beam that together define a sub-beam treatment area of ​​the sub-beam.

[0166]

[0165] Clause 49. A charged particle system comprising: a stage configured to support a sample having a sample surface; and a column configured to direct an array of sub-beams of charged particles onto a portion of the sample surface, a portion of which is assigned to each sub-beam, the stage and column configured to be controlled so that the portion is scanned by the sub-beams, the stage configured to move the sample parallel to the first direction by displacing the sample in steps and between steps in a direction angled to the first direction, and the column configured to repeatedly scan the multi-beam across the sample surface in a second direction during movement of the sample parallel to the first direction, so that with each step each sub-beam of the array of sub-beams scans an elongated area of ​​the portion assigned to it.

[0167]

[0166] Clause 50. A system according to clause 49, wherein the length of the portion of the elongated region and / or the length of the elongated region is equal to the pitch between the sub-beams at the sample surface.

[0168]

[0167] Clause 51. A charged particle system comprising: a stage for supporting a sample having a sample surface; and a column configured to direct a multi-beam of sub-beams of charged particles onto the sample surface, wherein either the stage is configured to move the sample relative to the column through a corresponding sequence of nominal processing positions; or the stage is configured to perform a sequence of leap displacements to move the sample relative to the column, each leap displacement being equal to or greater than twice the pitch of the multi-beams at the sample surface; the system is configured to scan the multi-beams across the sample surface at each of the nominal processing positions to process a sub-beam processing area with each sub-beam, the resulting sub-beam processing areas comprising a plurality of groups of interconnected sub-beam processing areas, the groups being separated from one another, and the nominal processing positions are such that at least one of the groups of interconnected sub-beam processing areas formed at one of the nominal processing positions is interleaved between at least two of the groups of interconnected sub-beam processing areas formed at a different one of the nominal processing positions.

[0169]

[0168] Clause 52. A system as described in Clause 51, wherein at least one of the leap displacements is smaller than a dimension of the column footprint parallel to the direction of the leap displacement, and the column footprint is defined as the smallest bounding box on the sample surface that encloses all of the sub-beam processing areas formed at one of the nominal processing positions.

[0170]

[0169] Clause 53. A system according to clause 51 or 52, wherein the interleaving forms an enlarged group of interconnected sub-beam processing areas comprising at least one interleaved group.

[0171]

[0170] Clause 54. A method for processing a sample using multiple beams of charged particles, comprising providing a column configured to direct a multiple of sub-beams of charged particles onto a sample surface of the sample, and sequentially performing the following steps: (a) using the column to repeatedly scan the multiple beams across the sample surface in a direction parallel to a second direction while moving the sample in a direction parallel to a first direction, thereby processing an elongated region on the sample surface with each sub-beam; (b) displacing the sample in a direction oblique or perpendicular to the first direction; and (c) repeating steps (a) and (b) a plurality of times to process further elongated regions with each sub-beam, wherein the resulting plurality of processed elongated regions define a sub-beam processing area for each sub-beam.

[0172]

[0171] Clause 55. A method of processing a sample using a multibeam of charged particles provided by a column configured to direct the multibeam of sub-beams of charged particles onto a sample surface of the sample, comprising the steps of: (a) using the column to repeatedly scan the multibeam in a direction parallel to a second direction across the sample surface, preferably across the sample surface for a path of the multibeam different from the first direction, while moving the sample in a direction preferably parallel to a first direction relative to the path of the multibeam a distance substantially equal to the pitch of the sub-beams in the multibeam at the sample surface in the first direction, thereby processing an elongated area on the sample surface with each sub-beam, preferably corresponding to the length of the pitch of the sub-beams at the sample surface; (b) displacing the sample in a direction oblique or perpendicular to the first direction relative to the path of the multibeam, which may preferably be a stepping direction, preferably whereby the direction of displacement of the sample is different from the first direction and preferably parallel to the second direction; and (c) performing steps (a) and ( b) repeating step b) a plurality of times to further process the elongated region with each sub-beam, the resulting plurality of processed elongated regions defining a sub-beam processing area for each sub-beam, preferably the sub-beam processing area for each sub-beam being sized in steps to be substantially cumulative of the displacement in the step direction, preferably the sub-beam processing area for each sub-beam being sized in the step direction to correspond to the pitch of the sub-beam processing areas in a second direction, preferably the elongated region overlaps the sub-beam processing area of ​​each sub-beam, preferably the multi-beam comprises an array of sub-beams having at least two dimensions, preferably the array comprises at least four sub-beams in one of the two dimensions of the array, preferably the at least four sub-beams are comprised in at least two groups and an unprocessed portion, preferably the unprocessed portion is between the two groups and the groups and the unprocessed portion extend across the entire array in the other dimension of the array.

[0173]

[0172] Clause 56. A method according to clause 54 or 56, wherein the maximum range of scanning of the multi-beam by the column in (a) is smaller than the minimum pitch of the sub-beams in the multi-beam on the sample surface.

[0174]

[0173] A method as described in clause 54 or 56, wherein the distance of displacement of the sample in clause 57.(b) is such that the multiple processed elongated regions in each sub-beam processing area partially overlap or are adjacent.

[0175]

[0174] Clause 58. A method according to any one of clauses 54 to 57, wherein the distance of movement of the sample in (a) is substantially equal to the pitch of the sub-beams in the multi-beam in the first direction on the sample surface.

[0176]

[0175] Clause 59. A method according to any one of clauses 54 to 58, wherein implementing (a) to (c) defines at least one group of sub-beam processing areas that are partially overlapping or adjacent to each other.

[0177]

[0176] Clause 60. A method according to any one of clauses 54 to 59, wherein the displacement of the sample in (b) is parallel to the second direction.

[0178]

[0177] Clause 61. A method according to any one of clauses 54 to 60, wherein the scanning of the multiple beams across the sample by the column in (a) is all carried out in the same direction.

[0179]

[0178] Clause 62. A method according to any one of clauses 54 to 60, wherein the scanning of the multiple beams over the sample by the columns in (a) is carried out in alternating directions.

[0180]

[0179] Clause 63. A method according to any one of clauses 54 to 62, wherein the movement of the sample in (a) during the repetition of (a) and (b) is in alternating directions.

[0181]

[0180] Clause 64. A tool (or system) according to any one of clauses 54 to 62, wherein the movement of the sample in (a) during the repetitions of (a) and (b) is all in the same direction.

[0182]

[0181] Clause 65. A method according to any one of clauses 54 to 64, further comprising, after steps (a) to (c), sequentially performing steps (d) of displacing the sample by at least twice the pitch of the sub-beams in the multi-beam on the sample surface, and (e) repeating steps (a) to (d), preferably including after steps (a) to (c) that the sub-beam processing area for each sub-beam is defined by a plurality of processed elongated regions, preferably by each sub-beam.

[0183]

[0182] Clause 66. The method of clause 65, wherein the sample is moved using independently actuable long-stroke and short-stroke stages, the maximum range of motion of the long-stroke stage being longer than the maximum range of motion of the short-stroke stage.

[0184]

[0183] Clause 67. The method of clause 66, wherein in steps (a) to (c) the sample is moved preferably exclusively using a short stroke stage.

[0185]

[0184] Clause 68. A method according to clause 66 or 67, wherein the sample is moved in step (d), preferably exclusively using a long stroke stage.

[0186]

[0185] Clause 69. A method according to any one of clauses 65 to 68, wherein the displacement of the sample in (d) is carried out with the sample positioned further away from the column than during the movement of the sample in (a) to (c).

[0187]

[0186] Clause 70. A method according to any one of clauses 65 to 69, wherein the column footprint is defined as the smallest bounding box on the sample surface that encloses all of the sub-beam processing areas from the implementation of (a) to (c), and the distance of sample displacement in (d) is substantially equal to or greater than the dimension of the footprint parallel to the direction of movement.

[0188]

[0187] A method described in any one of clauses 65 to 70, wherein the implementation of clause 71.(a) to (c) defines multiple groups of sub-beam processing areas, the sub-beam processing areas within each group partially overlapping or adjacent to each other and separated from the sub-beam processing areas of other groups.

[0189]

[0188] The method described in Clause 71, wherein the displacement of the sample in Clause 72.(d) is such that a group of sub-beam processing areas from one implementation of (a) to (c) is positioned relative to a group of sub-beam processing areas from another implementation of (a) to (c) to form at least one enlarged group of sub-beam processing areas comprising two or more groups of sub-beam processing areas.

[0190]

[0189] Clause 73. The method of clause 72, wherein the displacement of samples in (d) is performed such that an extended group is formed by interleaving groups from different implementations of (a) to (c).

[0191]

[0190] Clause 74. A method according to any one of clauses 71 to 73, wherein the column footprint is defined as the smallest bounding box on the sample surface that encloses all of the sub-beam processing areas from the implementation of (a) to (c), and the distance of sample displacement in (d) is less than the dimension of the footprint parallel to the direction of movement.

[0192]

[0191] Clause 75. The method of any one of clauses 54 to 74, further comprising detecting charged particles emitted from the sample.

[0193]

[0192] Clause 76. A method of processing a sample using multiple beams of charged particles using a column configured to direct the multiple sub-beams of charged particles onto a sample surface of the sample, comprising: moving the sample by a sequence of leap displacements through a corresponding sequence of nominal processing positions, each leap displacement being equal to or greater than twice the pitch of the multiple beams at the sample surface; and scanning the multiple beams across the sample surface at each nominal processing position to process a sub-beam processing area with each sub-beam, the resulting sub-beam processing areas comprising a plurality of groups of interconnected sub-beam processing areas, the groups being separated from one another, and the nominal processing positions being such that at least one of the groups of interconnected sub-beam processing areas formed at one of the nominal processing positions is interleaved between at least two of the groups of interconnected sub-beam processing areas formed at a different one of the nominal processing positions.

[0194]

[0193] Clause 77. The method described in Clause 76, wherein at least one of the leap displacements is smaller than a dimension of the column footprint parallel to the direction of the leap displacement, and the column footprint is defined as the smallest bounding box on the sample surface that encloses all of the sub-beam processing areas formed at one of the nominal processing positions.

[0195]

[0194] Clause 78. A method according to clause 76 or 75, wherein the interleaving forms an enlarged group of interconnected sub-beam processing areas comprising at least one interleaved group.

[0196]

[0195] Clause 79. A charged particle system comprising: a stage for supporting a sample having a sample surface; and a column configured to direct a multi-beam of sub-beams of charged particles onto the sample surface; the stage configured to move the sample between corresponding processing positions through a sequence of leap displacements, each leap displacement being equal to or greater than twice the pitch of the multi-beams at the sample surface; the system configured to scan the multi-beams across the sample surface at each nominal processing position to process a sub-beam processing area with each sub-beam, the resulting sub-beam processing areas comprising a plurality of separated groups of adjacent sub-beam processing areas, the processing positions being such that at least one of the groups formed at one of the processing positions is interleaved between at least two groups formed at different processing positions.

[0197]

[0196] Clause 80. A method of processing a sample using multiple beams of charged particles using a column configured to direct the multiple sub-beams of charged particles onto a surface of the sample, the method comprising moving the sample between corresponding processing locations through a sequence of leap displacements, each leap displacement being equal to or greater than twice the pitch of the multiple beams at the sample surface, at each processing location the multiple beams being scanned across the surface to process a sub-beam processing area with each sub-beam, the resulting sub-beam processing areas comprising a plurality of separated groups of adjacent sub-beam processing areas, the processing locations being such that at least one of the groups formed at one of the processing locations is interleaved between at least two groups formed at different processing locations.

[0198]

[0197] Clause 81. A method for processing a sample using multiple beams of charged particles using a column configured to direct the multiple beams of sub-beams of charged particles onto a surface of the sample, comprising: moving the sample between corresponding processing positions through a sequence of leap displacements, each leap displacement being equal to or greater than twice the pitch of the multiple beams at the sample surface; and at each processing position, relatively scanning the multiple beams across the surface to process a sub-beam processing area comprising a group of adjacent sub-beam processing areas to process a sub-beam processing area with each sub-beam, wherein moving the sample through the sequence of leap displacements comprises relatively displacing the sample along the beam path.

[0199]

[0198] Clause 82. A method according to clause 81, wherein the relative displacement of the sample along the beam path comprises increasing the distance between the sample and the column before moving the sample with a leap displacement.

[0200]

[0199] Clause 83. A method according to clause 82, wherein the relative displacement of the sample along the beam path comprises moving the sample with a leap displacement and then decreasing the distance between the sample and the column.

[0201]

[0200] Clause 84. A charged particle tool (or charged particle system) according to any one of claims 1 to 24, 35 to 47, 49 to 53 and 79 to 80, wherein the multi-beam comprises an array of sub-beams arranged in two different dimensions, preferably at least one of the dimensions comprising three or more sub-beams.

[0202]

[0201] Clause 85. A charged particle tool (or charged particle system) according to any one of claims 25 to 34 and 29 to 50, wherein the array of sub-beams comprises sub-beams arranged in two dimensions, at least one of the dimensions comprising three or more sub-beams.

[0203]

[0202] Clause 86. A charged particle tool or system according to any one of claims 1 to 23, 25 to 34, 40 to 47, 51 to 53, 79 to 80 and 84 or 85, wherein the treated area comprises an area of ​​the sample exposed to a sub-beam.

[0204]

[0203] Clause 87. A charged particle tool or charged particle system according to any one of claims 1 to 23, 25 to 34, 40 to 47, 51 to 53 and 79 to 80, 86 and 85 or 84, wherein the processing comprises evaluating a metric on the sample, for example inspecting or performing a measurement on the sample.

[0205]

[0204] Clause 88. A method according to any one of claims 54 to 78 and 81 to 83, wherein the multi-beam comprises an array of sub-beams arranged in two different dimensions, at least one of the dimensions comprising three or more sub-beams.

[0206]

[0205] Clause 89. A method according to any one of claims 54 to 78, 81 to 83 and 88, wherein the treated area comprises an area of ​​the sample exposed to a sub-beam.

[0207]

[0206] Clause 90. A method according to any one of claims 54 to 78, 81 to 83 and 88 and 89, wherein processing the sample comprises evaluating the sample, for example testing or performing measurements on the sample.

[0208] An evaluation tool according to an embodiment of the present disclosure may be a tool that performs a qualitative evaluation of a sample (e.g., pass / fail), or a tool that performs a quantitative measurement of a sample (e.g., size of a feature), or a tool that generates an image of a map of the sample. Examples of evaluation tools are inspection tools (e.g., to identify defects), review tools (e.g., to classify defects), and metrology tools, or tools that can perform any combination of evaluation functions associated with an inspection tool, review tool, or metrology tool (e.g., metrology inspection tool). The electron optical column 40 may be a component of an evaluation tool, such as an inspection tool, metrology inspection tool, or part of an electron beam lithography tool. Reference to a tool herein is intended to encompass a device, apparatus, or system, and a tool includes various components that may or may not be co-located, and may even be located in separate rooms, particularly for example, data processing components.

[0209]

[0208] The terms "sub-beam" and "beamlet" are used interchangeably herein and both are understood to encompass any radiation beam derived from a parent radiation beam by splitting or separating the parent radiation beam. The term "manipulator" is used to encompass any element that affects the path of a sub-beam or beamlet, such as a lens or deflector.

[0210]

[0209] References to multiple elements being aligned along a beam path or sub-beam path are understood to mean that each element is positioned along the beam path or sub-beam path.

[0211]

[0210] References to optical systems are understood to mean electron optical systems.

[0212]

[0211] References herein to control of electron-optical elements such as control lenses and objective lenses are intended to refer both to control by mechanical design and to control by predetermined applied operating voltages or potential differences, i.e., both passive and active control, for example by automatic control within the electron-optical column or selected by the user. The choice between active and passive control should be determined by the context.

[0213] References to a component or system of components or elements being controllable to manipulate 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 the described manner, and optionally using other controllers or devices (e.g., voltage and / or current sources) to control the component to manipulate the charged particle beam in this manner. For example, a voltage source, under the control of a controller or control system or control unit, may be electrically connected to one or more components to apply an electric potential to components such as, but not limited to, the control lens array 250, the objective lens array 241, the condenser lens 231, the corrector, the collimator element array 271, and the scan deflector array 260. An actuatable component, such as a stage, may be controllable to actuate and thus move relative to another component, such as the beam path, using one or more controllers, control systems, or control units to control the actuation of the component.

[0214]

[0213] The present invention may be embodied as a computer program. For example, the computer program may include instructions instructing the controller 50 to perform the following steps: The controller 50 controls the electron beam device to project the electron beam toward the sample 208. In one embodiment, the controller 50 controls at least one electron optical element (e.g., a multi-pole deflector or an array of scanning deflectors 260, 265) to act on the electron beam in the electron beam path. Additionally or alternatively, in one embodiment, the controller 50 controls at least one electron optical element (e.g., a detector 240) to act on the electron beam emitted from the sample 208 in response to the electron beam. Additionally or alternatively, the computer program may include instructions to instruct the controller 50 to provide any of the functionality described above, particularly with reference to Figures 13-23, including controlling the scanning of the column and the movement and stepping of the stage 209.

[0215] References to upper and lower, top and bottom, upward and downward should be understood to refer to directions parallel to the (typically, but not always, perpendicular) up-beam and down-beam directions of the electron beam or multi-beam impinging on the sample 208. Thus, references to up-beam and down-beam are intended to refer to directions relative to the beam path regardless of any gravitational fields that may be present.

[0216]

[0215] While the invention has been described in connection with various embodiments, other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims and clauses.

Claims

1. 1. A method for processing a sample using multiple beams of charged particles provided by a column that directs the multiple sub-beams of charged particles onto a sample surface of the sample, comprising: (a) using the column to repeatedly scan the multi-beam across the sample surface in a direction parallel to a second direction while moving the sample in a direction parallel to a first direction a distance substantially equal to a pitch of the sub-beams in the multi-beam at the sample surface in the first direction, thereby processing an elongated area on the sample surface with each sub-beam; (b) displacing the sample in a direction oblique or perpendicular to the first direction; (c) repeating steps (a) and (b) a plurality of times to process additional elongated regions with each sub-beam, the resulting plurality of processed elongated regions defining sub-beam processing areas for each sub-beam; The method includes sequentially performing the steps of:

2. 2. The method of claim 1, wherein a maximum range of scanning of the multi-beam by the column in (a) is less than a minimum pitch of the sub-beams in the multi-beam at the sample surface.

3. 3. The method of claim 1, wherein the distance of the sample displacement in (b) is such that the multiple processed elongated regions in each sub-beam processing area partially overlap or are adjacent.

4. 4. The method of any one of claims 1 to 3, wherein performing (a) to (c) defines at least one group of sub-beam processing areas that are overlapping or adjacent to each other.

5. The method of any one of claims 1 to 4, wherein the displacement of the sample in (b) is parallel to the second direction.

6. The method of any one of claims 1 to 5, wherein the scanning of the multiple beams over the sample by the columns in (a) is all performed in the same direction.

7. The method of any one of claims 1 to 6, wherein the scanning of the multiple beams over the sample by the columns in (a) is all performed in alternating directions.

8. The method of any one of claims 1 to 7, wherein the movements of the sample in (a) during the repetitions of (a) and (b) are all in the same direction.

9. After steps (a) to (c), (d) displacing the sample by a distance equal to at least twice the pitch of the sub-beams in the multi-beam at the sample surface; (e) repeating steps (a) to (d); and wherein after steps (a) to (c) the sub-beam processing area of ​​each sub-beam is preferably defined by the plurality of processed elongated regions by the respective sub-beam.

10. 10. The method of claim 9, wherein the sample is moved using independently actuable long-stroke and short-stroke stages, the long-stroke stage having a maximum range of motion longer than the maximum range of motion of the short-stroke stage.

11. The method of claim 10, wherein the sample is moved in steps (a) to (c), preferably exclusively using the short stroke stage.

12. 12. The method according to claim 10 or 11, wherein the sample is moved in step (d), preferably exclusively using the long stroke stage.

13. 13. The method of any one of claims 9 to 12, wherein the displacement of the sample in (d) is performed with the sample positioned further away from the column than during the movement of the sample in (a) to (c).

14. the column footprint is defined as the smallest bounding box on the sample surface that encloses all of the sub-beam treatment areas from implementations (a)-(c); 14. The method of any one of claims 9 to 13, wherein the distance of displacement of the sample in (d) is substantially equal to or greater than a dimension of the footprint parallel to the direction of movement.

15. A charged particle system, a stage for supporting a sample having a sample surface; a column for directing multiple sub-beams of charged particles onto the sample surface; Including, (a) using the stage to move the sample in a direction parallel to a first direction by a distance substantially equal to a pitch of the sub-beams in the multi-beam at the sample surface in the first direction, while using the column to repeatedly scan the multi-beam across the sample surface in a direction parallel to a second direction, thereby processing an elongated area on the sample surface with each sub-beam; (b) using the stage to displace the sample in a direction oblique or perpendicular to the first direction; (c) repeating (a) and (b) a plurality of times to process additional elongated regions with each sub-beam, the resulting plurality of processed elongated regions defining a sub-beam processing area for each sub-beam; a charged particle system for controlling the stage and the column to sequentially perform the steps of:

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