Evaluation apparatus and method

Abstract

The present disclosure relates to an apparatus and method for evaluating a sample using a plurality of charged particle beams. In one configuration, at least a subset of a beam lattice of a plurality of charged particle beams and respective target portions of a sample surface are scanned relative to each other to process the target portions. Signal charged particles from the sample are detected to generate a detection signal. By analyzing the detection signal, a sample surface topography map representing the topography of the sample surface is generated.

Description

Technical Field

[0001] Cross - reference to related applications

[0001] This application claims the benefit of U.S. Patent Application No. 63 / 407,008, filed on September 15, 2022, and European Patent Application Publication No. 22183148.0, filed on July 5, 2023, the entire contents of which are incorporated herein by reference.

[0002]

[0002] This disclosure relates to an apparatus and method for evaluating a sample using a plurality of charged particle beams.

Background Art

[0003]

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

[0004]

[0004] For example, to detect pattern defects, an evaluation tool called an evaluation system herein that uses a charged particle beam to evaluate an object that may be called a sample is known. These systems generally use electron microscopy techniques such as a scanning electron microscope (SEM). In an SEM, a primary electron beam of relatively high-energy electrons is targeted at a target in a final deceleration step in order to land on the sample with a relatively low landing energy. The electron beam is focused as a probing spot on the sample. Due to the interaction between the material structure at the probing spot and the landing electrons from the electron beam, signal electrons such as secondary electrons, backscattered electrons, or Auger electrons are emitted from the surface. The signal electrons can be emitted from the material structure of the sample. By scanning the primary electron beam as a probing spot across the sample surface, signal electrons can be emitted across the sample surface. By collecting these emitted signal electrons from the sample surface, a pattern inspection system can acquire an image representing the characteristics of the material structure of the sample surface.

[0005]

[0005] By increasing the number of beams incident on the sample simultaneously, a higher throughput can be achieved in the evaluation system. An evaluation system configured to operate in this way may be called a multi-beam system and can project a very large number of individual beams simultaneously onto the sample over a relatively large area on the sample surface, which may be called a field of view (FoV). Having a large FoV enables a high throughput. However, it has been found to be difficult to accurately focus the beams over such a large FoV.

Summary of the Invention

[0006]

[0006] It is an object of the present disclosure to provide a method and an apparatus that assist in improved control of the focus in a configuration where a plurality of charged particle beams are used to evaluate a sample.

[0007]

[0007] According to one aspect of the present invention, there is provided an evaluation apparatus for evaluating a sample using a plurality of charged particle beams, comprising: a sample support configured to support a sample having a sample surface; a charged particle device configured to project a beam lattice of the plurality of charged particle beams along a lattice path of the beam lattice toward the sample; a detector configured to detect signal charged particles from the sample and generate a detection signal when detecting the signal charged particles; and a control system configured to control the sample support, the charged particle device, and / or the detector to scan at least a subset of the beam lattice and respective target portions of the sample surface relative to each other to process the target portions, and to generate a sample surface topography map representing the topography of the sample surface by analyzing the detection signals detected in response to the scanning of at least the subset of the beam lattice and the respective target portions relative to each other.

[0008]

[0008] According to one aspect of the present invention, there is provided an evaluation apparatus for evaluating a sample using a plurality of charged particle beams, comprising: a sample support configured to support a sample having a sample surface; a charged particle device configured to project a beam lattice of the plurality of charged particle beams along a lattice path of the beam lattice toward the sample; a plurality of proximity sensors configured to face the sample, each proximity sensor being configured to measure the distance between the proximity sensor and the sample and provide output data; and a control system configured to import an externally derived topography map representing the topography of the sample surface measured using an external device, and to use the externally derived topography map and the output data from the plurality of proximity sensors to control the positioning of the sample and process the sample using the beam lattice.

[0009]

[0009] According to one aspect of the present invention, there is provided an evaluation apparatus for evaluating a sample using a plurality of charged particle beams, comprising: a sample support configured to support a sample having a sample surface; a charged particle device configured to project a beam lattice of the plurality of charged particle beams toward the sample along a lattice path of the beam lattice; a plurality of proximity sensors configured to face the sample, each proximity sensor being configured to measure a distance between the proximity sensor and the sample and provide output data; and a control system configured to receive a sample support topography map representing the topography of the surface of the sample support and, using the sample support topography map and the output data from the plurality of proximity sensors, control the positioning of the sample while processing the sample using the beam lattice.

[0010] According to one aspect of the present invention, there is provided an evaluation apparatus for evaluating a sample using a plurality of charged particle beams, comprising: a sample support configured to support a sample having a sample surface; a charged particle device configured to project a beam lattice of the plurality of charged particle beams toward the sample along a lattice path of the beam lattice; an optical measurement system configured to measure a topography map representing the topography of the sample surface; and a control system configured to control the positioning of the sample during processing of the sample by the beam lattice using the measured topography map. Desirably, the optical measurement system desirably includes an array of light sources and sensing elements arranged in a linear array, desirably dimensioned to extend over the entire maximum dimension of the sample, desirably in a sensing direction. Desirably, the array of light sources and sensing elements is configured with respect to the sample support such that when the sample moves in a scanning direction with respect to the linear array such that the sample is desirably angled with respect to the sensing direction, desirably the optical measurement system processes the sample surface, desirably the entire sample surface. The apparatus desirably further includes a detector configured to detect signal charged particles from the sample and provide an output. An evaluation apparatus is provided.

[0011]

[0011] According to one aspect of the present invention, there is provided an evaluation apparatus for evaluating a sample using a plurality of charged particle beams, the evaluation apparatus including: a sample support configured to support a sample having a sample surface; a charged particle device configured to project a beam lattice of the plurality of charged particle beams toward the sample along a lattice path of the beam lattice; a plurality of proximity sensors configured to face the sample, each proximity sensor being configured to measure a distance between the proximity sensor and the sample and to provide output data; and a control system configured to control the sample support to measure respective changes in the distance between the proximity sensors and the sample surface using the proximity sensors while moving the sample relative to the charged particle device over a range of positions and / or orientations, thereby generating a sample surface topography map representing the topography of the sample surface, and to control the position and / or orientation of the sample, which is controlled to move over successive ranges of different positions and / or orientations during processing, during processing of the sample by the beam lattice using the generated sample surface topography map.

[0012]

[0012] According to one aspect of the present invention, there is provided an evaluation apparatus for evaluating a sample using a plurality of charged particle beams, the evaluation apparatus comprising: a sample support configured to support a sample having a sample surface; a charged particle device configured to project a beam lattice of the plurality of charged particle beams toward the sample along a lattice path of the beam lattice; a plurality of proximity sensors configured to face the sample and preferably positioned at a distance from the lattice path, each proximity sensor being configured to measure a distance between the proximity sensor and the sample; and a control system configured to move the sample relative to the charged particle device over a range of sample positions and control the sample support to measure respective changes in the distance between the proximity sensors and the sample surface using the proximity sensors, thereby generating a sample surface topography map representing the topography of the sample surface, using the generated sample surface topography map to control the positioning of the sample during processing of the sample by the beam lattice, receiving a sample support topography map representing the topography of the sample support, and determining a calibrated sample surface topography map using the received sample support topography map, wherein preferably, using the generated sample surface topography map to control the positioning of the sample comprises any one of determining using, or preferably calibrating the generation of, the sample surface topography map such that the generated sample surface topography map is calibrated by the sample support topography map.

[0013]

[0013] According to one aspect of the present invention, there is provided a method for evaluating a sample using a plurality of charged particle beams, the method comprising: scanning at least a subset of a beam lattice of the plurality of charged particle beams and respective target portions of a sample surface to process the target portions with the beams; detecting signal charged particles from the sample and generating a detection signal upon detection of the signal charged particles; and generating a sample surface topography map representing the topography of the sample surface by analyzing the detection signals detected in response to the scanning of at least the subset of the beam lattice and the respective target portions with respect to each other.

[0014]

[0014] According to one aspect of the present invention, there is provided a method for evaluating a sample using a plurality of charged particle beams, the method comprising: importing an externally derived topography map representing the topography of the sample surface measured using an external device; and processing the sample using a beam lattice of the plurality of charged particle beams while controlling the positioning of the sample using the externally derived topography map and output data from a plurality of proximity sensors that measure the distance from the proximity sensors to the sample.

[0015]

[0015] According to one aspect of the present invention, there is provided a method for evaluating a sample using a plurality of charged particle beams, the method comprising: receiving a sample support topography map representing the topography of the surface of a sample support that supports the sample; and processing the sample using a beam lattice of the plurality of charged particle beams while controlling the positioning of the sample using the sample support topography map and output data from a plurality of proximity sensors that measure the distance from the proximity sensors to the sample.

[0016] According to one aspect of the present invention, there is provided a method for evaluating a sample using a plurality of charged particle beams, the method comprising optically measuring a topography map representing the topography of the sample surface of the sample, and using the measured topography map to control the positioning of the sample during the processing of the sample by a beam lattice of the plurality of charged particle beams.

[0017] According to one aspect of the present invention, there is provided a method for evaluating a sample using a plurality of charged particle beams, the method comprising generating a sample surface topography map representing the topography of the sample surface of the sample by measuring respective changes in the distance between a proximity sensor and the sample surface using the proximity sensor while moving the sample over a range of positions and / or orientations, and using the generated sample surface topography map to control the position and / or orientation of the sample, which is controlled to move over successive ranges of different positions and / or orientations during the processing of the sample by a beam lattice of the plurality of charged particle beams.

[0018] According to one aspect of the present invention, a method for evaluating a sample using a plurality of charged particle beams, comprising moving the sample over a range of sample positions and measuring respective changes in the distance between a proximity sensor and the sample surface using the proximity sensor to generate a sample surface topography map representing the topography of the sample surface of the sample; using the generated sample surface topography map to control the positioning of the sample during processing of the sample by a beam lattice of the plurality of charged particle beams; receiving a sample support topography map representing the topography of a sample support supporting the sample; and using the received sample support topography map to a) determine a calibrated sample surface topography map, preferably, in order to control the positioning of the sample, using the generated sample surface topography map means using, determining, or b) calibrating the generation of the sample surface topography map such that the preferably generated sample surface topography map is calibrated by the sample support topography map. A method is provided that includes any of the above.

[0019] The above and other aspects of the present disclosure will become more apparent from the description of exemplary embodiments in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0020]

Figure 1

[0020] It is a schematic diagram showing an exemplary charged particle beam inspection apparatus.

Figure 2

[0021] It is a schematic diagram showing an exemplary multi-beam apparatus which is a part of the exemplary charged particle beam inspection apparatus of FIG. 1.

Figure 3

[0022] It is a schematic diagram of an exemplary electron optical column including a condenser lens array, an objective lens array, and a detector array.

Figure 4

[0023] Schematic cross-sectional view of a part of an exemplary objective lens array and a detector array.

Figure 5

[0024] Bottom view of a part of the detector array of FIG. 4.

Figure 6

[0025] Bottom view of a modified version of a part of the objective lens array of FIG. 4.

Figure 7

[0026] Schematic diagram of an exemplary electron optical device including an objective lens array and a beam separator.

Figure 8

[0027] Schematic bottom view of a beam grid and a proximity sensor.

Figure 9

[0028] Schematic side view of a part of a sample on the down beam side of a configuration of the type shown in FIG. 8.

Figure 10

[0029] Shows an exemplary spatial distribution of target portions on the sample surface.

Figure 11

[0030] Schematically shows a charged particle beam having a common focal plane and three exemplary positions of a part of a sample corresponding to different focus condition settings.

Figure 12

[0031] Schematically shows different focal plane positions for a fixed sample position, and the different focal plane positions correspond to different focus condition settings.

Figure 13

[0031] Schematically shows different focal plane positions for a fixed sample position, and the different focal plane positions correspond to different focus condition settings.

Figure 14

[0031] Schematically shows different focal plane positions for a fixed sample position, and the different focal plane positions correspond to different focus condition settings.

Figure 15

[0031] Schematically shows different focal plane positions for a fixed sample position, and the different focal plane positions correspond to different focus condition settings.

Figure 16

[0032] Diagram of a further exemplary electron optical device.

Figure 17

[0033] For example, a schematic illustration of an exemplary distribution of different focal planes in a beam lattice including a 5×5 array of beams is shown.

Figure 18

[0034] Schematic illustrations of different stages of processing of a portion of a sample using five columns of beams focused on different focal planes are shown.

Best Mode for Carrying Out the Invention

[0021]

[0035] Here, exemplary embodiments are referred to in detail, and examples thereof are shown in the accompanying drawings. The following description refers to the accompanying drawings, and unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following description of the exemplary embodiments do not represent all implementations consistent with the present invention. Instead, those implementations are merely examples of apparatuses and methods consistent with aspects related to the present invention, as described in the appended claims.

[0022]

[0036] Improving the computing power of an electronic device while reducing its physical size can be achieved by significantly increasing the implementation density of circuit components such as transistors, capacitors, and diodes on an IC chip. This has been made possible by improvements in resolution that enable the fabrication of even smaller structures. For example, an IC chip the size of a fingernail and used in smartphones available before 2019 could contain over two billion transistors, and the size of each transistor is less than 1 / 1000 of a human hair. Therefore, it is not surprising that semiconductor IC manufacturing is a complex and time-consuming process with hundreds of individual steps. Even an error in a single step can dramatically affect the functionality of the final product. In certain situations, a single defect can cause the device to malfunction. The goal of the manufacturing process is to improve the overall yield of the process. For example, for a process with 50 steps (where a step may represent the number of layers formed on a wafer), to achieve a 75% yield, each individual step must have a yield of over 99.4%. If each individual step has a yield of 95%, the overall process yield is as low as 7%.

[0023]

[0037] In IC chip manufacturing facilities, while a high process yield is desirable, it is also essential to maintain a high substrate (i.e., wafer) throughput, which is defined as the number of substrates processed per hour. High process yield and high substrate throughput can be affected by the presence of defects. This is particularly true when operator intervention is required to investigate the defects. Therefore, high-throughput detection and identification of microscale and nanoscale defects by an inspection system (such as a scanning electron microscope ("SEM")) are essential to maintain high yield and low cost.

[0024]

[0038] The SEM includes a scanning device and a detector device. The scanning device includes an illumination device including an electron source for generating primary electrons and a projection device for scanning a sample, such as a substrate, with one or more focused beams of primary electrons. Together, at least the illumination device or illumination system and the projection device or projection system can be referred to collectively as an electron optical device or column. The primary electrons interact with the sample to generate secondary electrons. The detection device captures secondary electrons from the sample when the sample is scanned so that the SEM can generate an image of the scanned area of the sample. For high-throughput inspection, part of the inspection device uses a plurality of focused beams of primary electrons, i.e., a multi-beam. The component beams of the multi-beam can be referred to as sub-beams or beamlets. The multi-beam can scan different parts of the sample simultaneously. Thus, the multi-beam inspection device can inspect the sample much faster than a single-beam inspection device.

[0025]

[0039] Embodiments of known multi-beam inspection devices are described below.

[0026]

[0040] The figures are schematic. Accordingly, the relative dimensions of the components in the drawings are exaggerated for clarity. In the following description of the drawings, the same or similar reference numerals refer to the same or similar components or entities, and only the differences with respect to the individual embodiments are described. The description and the drawings are directed to electron optical devices, but 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 more generally references to charged particles, which are not necessarily electrons.

[0027]

[0041] Refer to FIG. 1, which is a schematic diagram showing an exemplary charged particle beam inspection apparatus 100, which may also be referred to as a charged particle beam evaluation system or simply an evaluation system. The charged particle beam inspection apparatus 100 of FIG. 1 includes a main chamber 10, a load lock chamber 20, an electron beam device 40, an equipment front end module (EFEM) 30, and a controller 50. The controller may be distributed among different components of the evaluation system, including, for example, within the electron beam device 40. The electron beam device 40 is located within the main chamber 10.

[0028]

[0042] The EFEM 30 includes a first loading port 30a and a second loading port 30b. The EFEM 30 may include one or more additional loading ports. The first loading port 30a and the second loading port 30b may receive, for example, a front-opening unified pod (FOUP) that houses a substrate (e.g., a semiconductor substrate or a substrate made of other materials) or a sample to be inspected (hereinafter, substrates, wafers, and samples are collectively referred to as "samples"). One or more robot arms (not shown) within the EFEM 30 carry the sample to the load lock chamber 20.

[0029]

[0043] The loading lock chamber 20 is used to remove the gas around the sample. This creates a vacuum, which is a local gas pressure lower than the pressure of the ambient environment. The loading lock chamber 20 can be connected to a loading lock vacuum pump system (not shown), which removes the gas particles within the loading lock chamber 20. By operating the loading lock vacuum pump system, the loading lock chamber can reach a first pressure below atmospheric pressure. After reaching the first pressure, one or more robotic arms (not shown) carry the sample from the loading lock chamber 20 to the main chamber 10. The main chamber 10 is connected to a main chamber vacuum pump system (not shown). The main chamber vacuum pump system removes the gas particles within the main chamber 10 such that the pressure around the sample reaches a second pressure lower than the first pressure. After reaching the second pressure, the sample is carried to an electron beam device and the sample can be inspected by the electron beam device. The electron beam device 40 can include a multi-beam electron optical device.

[0030]

[0044] The controller 50 is, for example, electronically signal-connected to the electron beam device 40 as a distributed component of the controller 50. The controller 50 can be a processor (such as a computer) configured to control the charged particle beam inspection device 100. The controller 50 can also include a processing circuit configured to execute various signal and image processing functions. In FIG. 1, the controller 50 is shown as being external to the structure including the main chamber 10, the loading lock chamber 20, and the EFEM 30, but it is understood that the controller 50 can be part of the structure. The controller 50 can be located within one of the component elements of the charged particle beam inspection device or the controller 50 can be distributed among at least two of the component elements. It should be noted that although the present disclosure provides an example of the main chamber 10 housing the electron beam inspection device, aspects of the present disclosure are not limited in a broad sense to a chamber housing the electron beam inspection device. Rather, it is understood that the foregoing principles can also be applied to other devices and other arrangements of devices operating under a second pressure.

[0031]

[0045] Referring now to FIG. 2, this is a schematic diagram representing an exemplary charged particle beam evaluation apparatus 40. The electron beam apparatus 40 can be provided as part of the exemplary charged particle beam inspection system 100 of FIG. 1. The electron beam apparatus 40 includes an electron source 201 and a charged particle column (or device) 230. The charged particle device 230 can be called or can include a projection device for directing a primary charged particle beam 202 towards a sample 208. The electron source 201 and the associated charged particle optics, which are components related to it, can be called an illumination device for generating the primary charged particle beam 202. The evaluation apparatus includes a sample support for supporting the sample 208. The sample support in this example includes a sample holder 207. The sample holder 207 holds the sample 208 (e.g., a substrate or a mask) for evaluation. The sample holder 207 is supported by a motorized stage or an actuated stage 209. The electron beam apparatus 40 further includes a detector 240. The detector 240 detects signal charged particles (e.g., electrons) from the sample 208. When the detector 240 detects signal charged particles, it generates a detection signal.

[0032]

[0046] The electron source 201 can include a cathode (not shown) and an extractor or an anode (not shown). During operation, the electron source 201 is configured to emit electrons from the cathode as primary electrons. The primary electrons are extracted or accelerated by the extractor and / or the anode to form the primary electron beam 202.

[0033]

[0047] The charged particle device 230 is configured to convert the primary electron beam 202 into a plurality of charged particle beams 211, 212, 213 and direct each beam onto the sample 208. For the sake of brevity, three beams are shown, but there can be dozens, hundreds, thousands, tens of thousands or even hundreds of thousands (or more) of beams. The beams can be referred to as beamlets or sub-beams. The plurality of charged particle beams can collectively be referred to as a multi-beam or a beam lattice. A beam lattice having such a large number of beams (e.g., more than a thousand beams) can have a field of view, for example, exceeding 0.5 mm, for example, in the range of 0.5 to 30 mm or 1 to 30 mm, for example, in the range of 0.5 to 15 mm.

[0034]

[0048] The controller 50 (e.g., a control system including distributed controllers) can be connected to various parts of the charged particle beam inspection apparatus 100 of FIG. 1, such as the electron source 201, the electron detection device 240, the charged particle device 230, and the operation stage 209. The controller 50 can perform various image and signal processing functions. The controller 50 can also generate various control signals for managing the operation of the charged particle beam inspection apparatus 100, including the operation of the electron beam device 40.

[0035]

[0049] The charged particle device 230 can be configured to focus, for example, beams 211, 212, and 213 onto the sample 208 for inspection, and can form three probe spots 221, 222, and 223 on the surface of the sample 208. The charged particle device 230 can be configured to deflect the primary beams 211, 212, and 213 to scan the probe spots 221, 222, and 223 over individual scanning areas within a section of the surface of the sample 208. In response to the incidence of the primary beams 211, 212, and 213 onto the probe spots 221, 222, and 223 on the sample 208, electrons including secondary electrons and backscattered electrons, which can be called signal charged particles, are generated from the sample 208. The secondary electrons typically have an electron energy of a magnitude of 50 electron volts (≤50 eV), and the backscattered electrons typically have an electron energy whose magnitude is between 50 electron volts (50 eV) and the landing energy of the primary beams 211, 212, and 213.

[0036]

[0050] The detector 240 can send the detection signal generated by the detector 240 to the controller 50 or a signal processing system (not shown, which can be part of the controller 50) as, for example, an image signal or a detection signal, and can construct an image of the corresponding scanned area of the sample 208, for example. The detector 240 can be at least partially incorporated within the charged particle device 230 or can be separated therefrom. For example, a second optical column can direct secondary electrons to the detector 240.

[0037]

[0051] 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 part of the processing function of the controller. Accordingly, the image acquirer may include at least one or a plurality of processors. The image acquirer may be communicatively coupled to a detector 240 that enables signal communication, such as, among others, a conductor, an optical fiber cable, a portable storage medium, IR, Bluetooth, the Internet, a wireless network, a wireless radio, or a combination thereof. The image acquirer can receive a detection signal from the detector 240, process the data contained in the signal, and construct an image therefrom. Accordingly, the image acquirer can acquire an image of the sample 208. The image acquirer can also perform various post-processing functions, such as generating a contour and superimposing an indicator on the acquired image. The image acquirer may be configured to perform adjustments such as brightness and contrast of the acquired image. The storage may be a storage medium such as a hard disk, a flash drive, cloud storage, random access memory (RAM), or other types of computer-readable memory. The storage may be coupled to the image acquirer and used to store the scanned raw image data as the original image or the post-processed image.

[0038]

[0052] The image acquirer can acquire one or more images of the sample 208 based on the imaging signal received from the detector 240. The imaging signal may correspond to a scanning operation for performing charged particle imaging. The acquired image may be a single image including a plurality of imaging areas. The single image may be stored in a storage device. The single image may be an original image that can be divided into a plurality of regions. Each of these regions may include one imaging area including features of the sample 208. The acquired image may include a plurality of images of a single imaging area of the sample 208 sampled a plurality of times over a certain period. These plurality of images may be stored in the storage device. The controller 50 may be configured to perform an image processing step using a plurality of images of the same location of the sample 208.

[0039]

[0053] The controller 50 may include a measurement circuit (e.g., an analog-to-digital converter) to obtain the distribution of the detected secondary electrons. A part of the controller for such a function may be included in or in proximity to the detector. The electron distribution data collected during the detection time window can be combined with the corresponding scanning path data of each of the primary beams 211, 212, and 213 incident on the sample surface and 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. Accordingly, the reconstructed image can be used to reveal any defects that may be present in the sample.

[0040]

[0054] The controller 50 can control the actuating stage 209 to move the sample 208 during the inspection of the sample 208, for example, to provide a scanning movement of the stage with respect to the path of the primary beam. The controller 50 can enable the actuating stage 209 to move the sample 208 in a certain direction, such as at least during the inspection of the sample, preferably continuously, for example, as part of the scanning movement of the stage at a constant speed. The controller 50 can control the movement of the actuating stage 209 such that the actuating stage 209 changes the moving speed of the sample 208 according to various parameters. For example, the controller can control the stage speed (including its direction) according to the characteristics of the inspection steps and / or the scanning of the scanning process, as disclosed in European Patent Application Publication No. A21171877.0 filed on May 3, 2021, which is incorporated herein by reference, at least as long as it relates to a strategy combining at least the steps and scanning of the stage. The control of the actuating stage can enable the operation of the stage, and thus the operation of the sample, to position the sample dynamically with respect to the path of the primary beam.

[0041]

[0055] Figure 3 is a schematic diagram of an exemplary charged particle device 41 used in the evaluation apparatus. For simplicity of illustration, the lens array is schematically depicted herein by an elliptical array. Each elliptical shape represents one of the lenses in the lens array. The elliptical shape is conventionally used to represent a lens by analogy with the biconvex shape often employed in optical lenses. In connection with charged particle devices as discussed herein, it should be understood that the lens array does not necessarily require any physical element adopting a biconvex shape because it usually operates electrostatically. As described below, the lens array can instead include a plurality of plates having apertures. Each plate having an aperture can be called an electrode. The electrodes can be provided in series along the path of the beam lattice of a plurality of charged particle beams (which can also be called sub-beams). Therefore, the electrodes are also in series along the path of the charged particle beams of the beam lattice.

[0042]

[0056] The electron source 201 directs electrons towards an array of condenser lenses 231 that form part of the charged particle device 230. The electron source 201 is preferably a high-brightness thermal field emitter having a good compromise between brightness and total emission current. There can be dozens, hundreds, thousands or even tens of thousands of condenser lenses 231. The array of condenser lenses 231 can include a multi-electrode lens and in particular has a structure based on European Patent Application Publication No. 1602121A1, which is incorporated herein by reference for the disclosure of a lens array (providing one lens per sub-beam) for splitting an electron beam into a plurality of sub-beams. The condenser lens array can take the form of at least two (preferably three) plates that serve as electrodes, and the apertures in each plate are aligned with the apertures in other plates to define the path of the charged particle beam through the plate. At least two of the plates are maintained at different potentials during operation to achieve the desired lens effect. Between the plates of the condenser lens array, there are electrical insulating plates made of, for example, an insulating material such as ceramic or glass, which have one or more apertures for the charged particle beam. Additionally or alternatively, one or more of the plates can be characterized by apertures that each have their own electrode and are arranged, for example, in a group of apertures having an array of electrodes around their periphery or a common electrode. In a variant form, one or more of the plates can include a plurality of portions or strips having a plurality of apertures. In a further alternative configuration, a macro collimator is provided instead of the condenser lens array. The macro collimator acts on the beam from the electron source 201 before the beam is split into a multi-beam. The macro collimator can be implemented magnetically, electrostatically or magnetically and electrostatically.

[0043]

[0057] In some embodiments, the condenser lens array is formed from three plate arrays, in which the charged particles have the same energy when entering and exiting each lens, and this configuration can be called an Einzel lens. Thus, dispersion occurs only inside the Einzel lens itself (between the inlet and outlet electrodes of the lens), thereby limiting off-axis chromatic aberration. When the thickness of the condenser lens is thin, for example, a few millimeters, the influence of such aberration is small or negligible.

[0044]

[0058] Each condenser lens in the array guides electrons into respective beams 211, 212, 213 that are focused at respective intermediate foci 233. A collimator or an array of collimators can be positioned to operate at respective intermediate foci 233. The collimator can take the form of a deflector 235 provided at the intermediate focus 233. The deflector 235 is configured to bend each beam 211, 212, 213 by an effective amount to ensure that the principal ray (which can also be called the beam axis) is incident on the sample 208 substantially perpendicular (i.e., at approximately 90° to the nominal surface of the sample). It should be noted that in a configuration with a macro condenser lens, the condenser lens can perform or contribute to the collimation of the source beam or, in one embodiment, multiple beams.

[0045]

[0059] The objective lens array 401 is provided on the down-beam side of the deflector 235. The objective lens array 501 includes objective lenses for each beam 211, 212, 213. The objective lens array 401 projects the beams 211, 212, 213 onto the sample 208. The objective lens array 401 can include two or more, preferably at least three, plate electrode arrays connected to respective potential sources.

[0046]

[0060] Optionally, the control lens array 250 is provided between the deflector 235 and the objective lens array 401. The control lens array 250 includes control lenses for each of the beams 211, 212, 213. The control lens array 250 provides an additional degree of freedom for controlling the characteristics of the beams 211, 212, 213. The control lens array 250 may include two or more, preferably at least three, plate electrode arrays connected to respective potential sources. The function of the control lens array 250 is to optimize the beam opening angle with respect to the beam reduction ratio and / or control the beam energy delivered to the objective lens, and each of the objective lenses guides the respective beams 211, 212, 213 onto the sample 208. In one embodiment, the control lens array may be considered to be part of the objective lens in that it is, for example, an additional plate associated with the objective lens array.

[0047]

[0061] Optionally, an array of scanning deflectors 260 is provided between the control lens array 250 and the objective lens array 401. The array of scanning deflectors 260 includes scanning deflectors for each of the beams 211, 212, 213. Each scanning deflector is configured to deflect the respective beams 211, 212, 213 in one or two directions in order to scan the beam in one or two directions across the entire sample 208. Alternatively, a macro scanning deflector for scanning the charged particle beam on the sample 208 may be provided. The macro scanning deflector may be provided on the up-beam side of the control lens array 250. In one embodiment, such a macro scanning deflector may act on the source beam and may be present together with a macro condenser lens.

[0048]

[0062] The detector module 402 of the detector is provided within the objective lens or between the objective lens and the sample 208 to detect signal electrons / particles from the sample 208. An exemplary structure of such a detector module 402 will be described below. Note that the detector may, in addition or instead, have detector elements on the up-beam side along the primary beam path of the objective lens array 401 or further the control lens array 250. The detector module can be an array of detector elements (e.g., a detector array). Each element can be associated with an individual beam and is positioned, for example, to detect signal particles generated by the individual beam.

[0049]

[0063] The charged particle device 41 of FIG. 3 can be configured to control the landing energy of electrons on the sample 208 by varying the potentials applied to the electrodes of the control lens and the objective lens. The control lens and the objective lens can cooperate and can be referred to as an objective lens assembly. The landing energy can be selected to increase the emission and detection of secondary electrons depending on the nature of the sample being evaluated. The detector module can be included in the objective lens assembly.

[0050]

[0064] The objective lens can be configured to reduce the electron beam by a factor greater than 10, desirably in the range of 50 to 100 or more. The objective lens can include three electrodes, namely, an intermediate electrode, a lower electrode, and an upper electrode. The upper electrode can be omitted. An objective lens having only two electrodes can have lower aberration than an objective lens having more electrodes. A three-electrode objective lens can enable a more powerful lens because of the larger potential difference between the electrodes. Additional electrodes (i.e., three or more electrodes) provide additional degrees of freedom for controlling the electron trajectory, for example, to focus not only secondary electrons but also the incident beam.

[0051]

[0065] In some embodiments, the objective lens array assembly includes a detector having a detector module 402 on the down-beam side of at least one electrode of the objective lens array 401. The detector module 402 can include or further take the form of a detector array. In one embodiment, at least a portion of the detector is adjacent to and / or integrated with the objective lens array 401. For example, the detector module 402 can be implemented by integrating a CMOS chip detector with the bottom electrode of the objective lens array 401. The integration of the detector module 402 into the objective lens array can replace a secondary column. The CMOS chip is preferably oriented to face the sample (e.g., due to the small distance between the sample and the bottom of the electron optical system, which can be 10 - 400 micrometers, desirably 50 - 200 micrometers, optionally about 100 micrometers). Note that even in the situation where the detector is on the up-beam side of the most down-beam side electron optical element of the charged particle device, the separation distance between the most down-beam side electron optical element and the sample (e.g., about 100 micrometers) can be close, e.g., a similar distance. In one embodiment, electrodes for capturing signal charged particles are formed in the top metal layer of the CMOS device. The electrodes can be formed in other layers of the substrate (e.g., of the CMOS chip). The CMOS power and control signals can be connected to the CMOS by silicon through vias. For robustness, preferably, the bottom electrode consists of the following two elements: a CMOS chip and a passive silicon plate having holes. The plate shields the CMOS from high electric fields.

[0052]

[0066] In one embodiment, a single electrode surrounds at least some of the apertures. In one configuration, the single electrode is assigned, for example, around each aperture. In another embodiment, a plurality of electrode elements are provided around each aperture, for example, as detector elements. Signal charged particles captured by the electrode elements surrounding one aperture can be combined into a single detection signal or used to generate independent detection signals. The electrode elements can be divided radially (i.e., to form a plurality of concentric rings), angularly (i.e., to form a plurality of sector portions), both radially and angularly (to provide a configuration such as a dartboard) or in a grid pattern (e.g., as a chessboard), or divided in any other convenient way.

[0053]

[0067] An exemplary embodiment of a detector integrated with the objective lens array 401 is shown in FIG. 4, which shows a schematic cross-section of a part of the objective lens array 401. In this embodiment, the detector preferably includes a detector module 402 including a plurality (e.g., an array) of detector elements 405 (e.g., sensor elements such as capture electrodes) as an array of detector elements (i.e., preferably a plurality of detector elements in a pattern or arrangement over the entire two-dimensional surface). In this embodiment, the detector module 402 is provided on the output side of the objective lens array. The output side is the output side of the objective lens array 401. FIG. 5 is a bottom view of the detector module 402 including a substrate 404 provided with a plurality of detector elements (capture electrodes 405) each surrounding a beam aperture 406. The beam aperture 406 can be formed by etching the substrate 404. In the configuration shown in FIG. 5, the beam aperture 406 is shown as a rectangular array. The beam apertures 406 can also be arranged in different ways (e.g., a closest-packed hexagonal array as depicted in FIG. 6).

[0054]

[0068] The integrated detector module 402 described above is particularly advantageous when used with an evaluation device (e.g., including a device) having an adjustable landing energy, as secondary electron capture can be optimized for a range of landing energies. A detector module having an array or in that form can be integrated not only into the lowest electrode array but also into other electrode arrays. Further details and alternative configurations of the detector module integrated into the objective lens can be found in European Patent Application Publication No. 20184160.8, which is incorporated herein by reference.

[0055]

[0069] The power supply can be provided to apply respective potentials to the electrodes of the control lenses of the control lens array 250, the electrodes of the objective lens of the objective lens array 401, the electrodes of the condenser lenses of the condenser lens array, or any electron optical component of the charged particle device 41, such as a detector module (e.g., when integrated into the objective lens array or when the objective lens and the detector module are separate components). The controller 50 can control the potentials applied to the electron optical components such as the electrodes of the condenser lens array, the objective lens array, and / or the control lens array.

[0056]

[0070] The charged particle device 41 can include other electron optical components such as a charged particle corrector, for example, as a corrector array for adjusting the alignment of the electron source with respect to the sample or the alignment between the beams of a multi-beam and the focus of different groups or individual beams of the beam lattice. Such a corrector can be controlled, for example, to operate dynamically and / or statically during the setup, maintenance, or calibration of the charged particle device 41.

[0057]

[0071] In one embodiment, an array of charged particle devices (i.e., a device array) is provided. The array can include any plurality of the charged particle devices (e.g., electron optical columns) described herein. Each of the charged particle devices in the array focuses a respective plurality of charged particle beams onto different regions of the same sample 208. Each of the charged particle devices in the array can derive a respective plurality of charged particle beams from different respective electron sources 201. Each electron source 201 can be one of the plurality of electron sources 201. At least a subset of the plurality of electron sources 201 can be provided as an electron source array. The electron source array can include a plurality of emitters on a common substrate. By simultaneously focusing a plurality of charged particle beams from different charged particle devices onto different regions of the same sample, a larger region of the sample 208 can be simultaneously exposed to the charged particle beams. Thus, a larger region of the sample can be processed (e.g., evaluated) at once. The charged particle devices in the device array can be arranged adjacent to each other such that each of the respective plurality of beams is projected onto an adjacent region of the sample 208. Any number of charged particle devices can be used in the array. Preferably, the number of charged particle devices ranges from 9 to 200. When referring to a single charged particle device, electron optical device or system or column, each charged particle device in the array can be configured in any of the methods described herein. Alternatively or in addition, one or more of the charged particle devices in the array can be configured to project a single beam.

[0058]

[0072] Figure 7 schematically shows a further example of a charged particle device 41. The same reference numerals are given to the same features as described above. For the sake of brevity, such features are not described in detail with respect to Figure 7. For example, the electron source 201, the condenser lens 231, the objective lens array 401 and the sample 208 (e.g., on the sample support 207) may be as described above. In this example, instead of the deflector array of the type described above with reference to Figure 3, a macro collimator 270 is provided. Such a macro collimator can be a macro lens which can be magnetic, electrostatic or both. In other embodiments, a deflector array can be used to at least contribute to the collimation of the beam, and thus the deflector array is for a more delicate deflection in the collimation direction than the operation of the macro collimator 270. Such a configuration can also include an array of multiple deflectors (e.g., each aperture having multiple electrodes) for more delicate collimation. In one configuration, the condenser lens 231 can include a single plate defining a beam limiting aperture array, with multiple apertures defined within the single plate and one or more macro electrodes associated with a single aperture. Such a beam limiting aperture array and associated macro electrodes can also form a condenser lens array to focus the generated beam to an intermediate focus, desirably corresponding to the position of the collimator 270.

[0059]

[0073] As described above, in some embodiments, a detector can be provided between the objective lens array 401 and the sample 208. The detector can face the sample 208. Instead, as shown in Figure 7, the detector 240 can be mounted such that the objective lens array 401 is present between the detector 240 and the sample 208.

[0060]

[0074] In one embodiment, the deflector array 95 is provided between the detector 240 and the objective lens array 401. In one embodiment, the deflector array 95 includes a Wien filter array, and thus, the deflector array 95 may be referred to as a beam separator. The deflector array 95 is configured to provide a magnetic field and an electrostatic field. The electrostatic field and the magnetic field act together to separate charged particles projected onto the sample 208 from signal particles, e.g., electrons from the sample 208. Due to the action of the fields, the signal particles are guided toward the detector 240.

[0061]

[0075] In one embodiment, the detector 240 is configured to detect signal particles with reference to the energy of the charged particles, i.e., depending on the bandgap in such a semiconductor-based type of detector. Such a detector 240 may be referred to as an indirect current detector. Secondary electrons emitted from the sample 208 obtain energy from the field between the electrodes. The secondary electrons have sufficient energy when they reach the detector 240. In a different arrangement, the detector 240 may be, for example, an electron-photon converter of a fluorescence strip between beams located on the up-beam side along the main beam path with respect to the Wien filter, e.g., a scintillator array. The main beam passing through the Wien filter array (magnetic and electrostatic strips orthogonal to the main beam path) has a path substantially parallel to the up-beam side and the down-beam side of the Wien filter array, while the signal electrons from the sample are guided by the Wien filter array toward the scintillator array. The electron-photon converter is optically coupled to a photon-electron converter to convert any photons generated and emitted by the electron-photon converter. The photon-electron converter may be electrically connected to an electronic circuit for processing the detection signal. In different embodiments, the photon-electron converter may be inside or outside the charged particle device. In one embodiment, a photon coupling may be made to a remote optical detector via a photon transport unit (e.g., an array of optical fibers), and the optical detector generates a detection signal when detecting photons.

[0062]

[0076] As described in the introduction section of this specification, projecting a plurality of charged particles onto a sample increases throughput compared to a single beam, but makes focus control more difficult. The plurality of charged particles may be referred to as a beam lattice. The quality of the focus of each beam on the sample surface is determined by the position of the focal plane of the beam relative to the position on the sample surface where the beam is incident. (In this specification, generally reference is made to the focal plane of a beam, the focal planes of multiple beams, the beam lattice or the selection of beams of the beam lattice, but it is understood that the focal plane of a single beam can be expressed as the focus.) When the position of the focal plane is within an acceptable range of the corresponding portion of the sample surface, the quality of the focus is acceptable. Controlling the position of the focal plane of each beam relative to the sample surface is difficult due to the typically non-planar topography of the sample surface and the relatively large size of the intersection region between the path of the beam lattice (which can be referred to as the lattice path) and the sample.

[0063]

[0077] At the time of drafting this specification, the change in displacement of the sample surface away from or outside the sample surface (e.g., orthogonal to the plane of the sample surface) can be about 50 micrometers, for example 20 to 40 micrometers. This can be a significant proportion of the average distance between the sample surface and the facing surface of the charged particle device 41, such as the detector 240. Where the field of view of the charged particle device 41 is relatively large, for example 0.5 to 300 mm, the magnitude of the range of change in the distance from the sample surface to the facing surface of the charged particle device 41 across the field of view can be the entire range or at least a significant portion of the change in displacement of the sample surface away from or outside the sample surface. However, for the operation of the evaluation apparatus, the beams of the beam lattice are ideally focused on the sample surface where the beam is incident.

[0064]

[0078] It is possible to obtain information regarding the topography of the sample surface using a proximity sensor. FIG. 8 is a schematic bottom view (looking in the up-beam direction) of a beam lattice 102 of a plurality of charged particle beams. The beam lattice 102 has any shape including rectangular or hexagonal. The beam lattice 102 has a path 103 that defines the outermost radial extent of the beam lattice 102. All of the beams of the beam lattice 102 are included within the path 103. Accordingly, the path 103 defines the volume containing the beams between the charged particle device and the sample 208. There are no beams outside the path 103. In this example, four proximity sensors 104 are provided outside the path 103 of the beam lattice 102. The proximity sensors 104 can be described as being positioned at a distance from the path 103 of the beam lattice 102. The proximity sensors 104 can be positioned outside the path 103 due to a lack of space for placing the proximity sensors within the path 103. Each proximity sensor 104 faces the sample 208 and can measure the distance Zm between the proximity sensor 104 and the sample 208 (e.g., the distance between the proximity sensor 104 and a part of the sample surface facing the proximity sensor 104). Each proximity sensor 104 provides output data representing the result of the measurement. In some configurations, each proximity sensor 104 optionally includes one or more capacitance sensors configured to operate in differential mode. The output data from the proximity sensors 104 is used to control the positioning of the sample 208 (including both position and orientation, e.g., displacement in the rotational direction around an axis of the coordinate system of the beam lattice and / or the sample with respect to the axis of the beam lattice and / or the sample) to improve the quality of the focus of the charged particle beams of the beam lattice 102 on the sample 208. The goal is to place the portion of the sample surface processed by each beam at or near the position of the focal plane of that beam.

[0065]

[0079] FIG. 9 is a schematic side view of a portion of the sample 208 on the down beam side of the configuration of the type shown in FIG. 8. In this case, the beam grid 102 is projected along the grid path 103 from an electron optical system of a charged particle device that provides the beam grid 102 (which may include an objective lens array 401 including an objective lens and / or a detector module 402 of a detector as described above with reference to FIGS. 1-7). In the example shown, the beam grid 102 has a common focal plane 108 for all charged particle beams of the beam grid 102. The quality of the focus is acceptable for a range of positions on the sample surface that are close to the position of the focal plane 108. The range of positions can be defined by an upper limit 110 and a lower limit 112 as schematically shown in FIG. 9. FIG. 9 shows how changes in the topography of the sample 208 (which may be referred to as non-flatness) can cause focus problems. Such changes in the topography of the sample can be considered to be changes in the displacement of the sample surface that are substantially parallel to the plane of the sample support or at least deviate from the ideal plane of the sample surface that could be the ideal sample position on the sample support. Even if the proximity sensor 104 indicates that the sample 208 is perfectly positioned, i.e., the sample surface is at the focal plane 108, changes in the topography of the sample 208 can cause focus problems. In such a situation, the proximity sensor 104 indicates that the portion of the sample surface facing the proximity sensor 104 is positioned at the focal plane 108 and that portions of the sample surface spaced therefrom, for example, portions of the sample surface within the grid path 103, are not positioned there. Due to the topography of the sample 208, portions of the sample surface within the grid path 103 are positioned outside a range of positions that produce an acceptable quality of focus, while portions of the sample surface facing the proximity sensor 104 can be positioned at the focal plane 108.Depending on the direction and shape (e.g., convex or concave) of the curvature of the sample surface in the grid path 103, the sample surface may be entirely below or above the positions within the range defined by the upper limit 110 and the lower limit 112, or a portion of the sample surface within the grid path 103 may pass through the focus of the beam grid, and only the portion of the sample surface may be positioned above and / or below the upper and lower limits. Embodiments of the present disclosure described below are intended to address such situations.

[0066]

[0080] In some embodiments, an evaluation apparatus is provided. The evaluation apparatus is configured to be suitable for evaluating (e.g., inspecting for defects or measuring sample features) a sample 208 using a plurality of charged particle beams. The plurality of charged particle beams may be referred to as a beam grid. The evaluation apparatus includes a sample support for supporting the sample 208. The sample support may take any of the forms described above with reference to FIG. 2. For example, the sample support may include, for example, a sample holder 207 and / or a motorized stage 209. The sample support is controllable to adjust the position and / or orientation of the sample 208, for example, at least one degree of freedom. The evaluation apparatus includes, for example, a charged particle device that projects a beam grid 102 along a grid path 103 of the beam grid 102 towards the sample 208, as schematically shown in FIG. 9. The charged particle device may take any of the forms described above with respect to the charged particle device 41 (which may also be referred to as an electron optical device or an electron optical column), particularly with reference to FIGS. 3 and 7. The evaluation apparatus includes a detector. The detector detects signal charged particles from the sample 208. The detector generates a detection signal when it detects the signal charged particles. The detector may take any of the forms described above with respect to the detector 240, particularly with reference to FIGS. 2 to 7. The detector may include a detector module 402 as described with reference to FIGS. 3 to 6. Optionally, the detector may include an array of detector elements having individual detector elements for each beam of the beam grid.

[0067]

[0081] In some embodiments, the evaluation apparatus further includes a control system 500. The control system 500 controls the evaluation apparatus to perform various functions as described below. The control system 500 may include or may be composed of a controller 50 that takes any of the forms described above with reference to FIG. 1. The control system 500 may cause the evaluation apparatus to perform functions by controlling the sample support, the charged particle device, and / or the detector. The control system 500 may include a single unit configured to perform all of the control functionality, or may include a distributed system of units that enables the necessary functionality to be achieved together. Such a distributed system may be located within different components or modules of the evaluation apparatus and / or may have one or more elements associated therewith, such as, by way of non-limiting list, the motorized stage 209 and the charged particle device 41. The control system 500 may be at least partially computer-implemented. Any suitable combination of elements (e.g., CPU, RAM, data storage, data connection, sensor, etc.) may be provided and suitably programmed to achieve some or even all of the specified functionality. References herein to an apparatus, device, or system being configured to perform functionality are intended to include instances where the control system 500 is configured to perform the functionality (e.g., by being suitably programmed to provide control signals that cause the functionality to occur).

[0068]

[0082] In one embodiment, the control system 500 controls the sample support and / or the charged particle device to scan at least a subset of the beam lattice 102 and each target portion 114 of the sample surface relative to each other. Accordingly, the charged particle beam of the beam lattice (or at least a subset of the beam lattice 102) may have a corresponding target portion 114. An exemplary spatial distribution of the target portions 114 is shown in FIG. 10 (described below). All of the charged particle beams of the beam lattice 102 may be scanned across their respective target portions 114, or a portion (subset) less than all may be scanned across their respective target portions 114. In some configurations, a subset of the beam lattice (i.e., a subset of the available charged particle beams) is selected with reference to a predetermined topographic map of the sample surface. The subset may be selected, for example, to avoid regions on the sample surface having damaged or locally deviated from the average topography (e.g., specifically high peaks or deep depressions).

[0069]

[0083] A portion of the sample surface having a local topography that deviates excessively from the average topography is positioned with respect to the paths of a selected subset of the beams of the beam lattice 102 (or a plurality of beams of the selected subset), such that that portion of the sample surface is too far from the focal plane of each beam of the selected subset to be in focus. That is, the position of the sample surface is at a distance exceeding a focus threshold from the focal plane of each beam along the path of each beam of the selected subset. The selected subset may include contiguous portions of the beam lattice 102. The contiguous portions of the beam lattice 102 are composed of a part of the beam lattice in which all charged particle beams are directly adjacent to at least every other charged particle beam in the selected subset. The selected subset may alternatively or additionally be a group of one or more charged particle beams, each group being separated from other groups by one or more charged particle beams outside the subset (not part of the subset), including a distribution of the groups. The selection of the subset may be achieved by one or more of the following (as a non-exhaustive list): disabling non-selected beams of the beam lattice so that they do not reach the sample, controlling the detector to be in a non-transmission setting where the detector does not transmit a detection signal, deselecting detection signals from detectors associated with non-selected beams so that they are not processed, or selecting detection signals only from detector elements associated with selected beams of the beam lattice.

[0070]

[0084] Scanning of the charged particle beam on the target portion 114 (i.e., the target portion 114 corresponding to that charged particle beam) or dynamic intersection of the path of the charged particle beam on the surface of the target portion 114 may be referred to as processing of that target portion 114. The target portion 114 may have any desired and suitable shape. In one embodiment, the target portion 114 may be rectangular. Signal electrons moving from the target portion 114 during processing may be detected by a detector and used, for example, with an image acquirer as described above, to generate an image of the target portion 114.

[0071]

[0085] The shape and spatial distribution of the target portion 114 on the sample surface are not particularly limited. FIG. 10 shows the expected arrangement of the target portion 114 for 12 adjacent charged particle beams of the beam lattice. Although four target portions 114 in three rows are shown, the beam lattice will typically process many more target portions 114, for example, hundreds or thousands of target portions 114 simultaneously. In this example, each target portion 114 is processed by a different charged particle beam of the beam lattice. The target portions 114 can be processed simultaneously by different charged particle beams. The processing can include scanning each charged particle beam over its respective target portion 114, for example, by raster scanning. In this example, each target portion 114 is fully processed, and the resulting processed target portions 114 form a single continuous processed region without gaps between the processed target portions 114. In other configurations, the target portions 114 can be processed to leave gaps between different processed regions. In one embodiment, the target portion 114 can be rectangular, and although the shapes correspond, smaller rectangular regions can be processed. This is illustrated in FIG. 10, where each of the rectangular regions corresponding to the target portion 114 is only partially processed. Thus, a part of each target portion 114 of the sample surface, which consists of only a part of the region that can be processed at the target position 114, is processed. Such a part of the region is the partial region labeled 114' at each target portion 114. The part of the target portion 114 that is processed as the partial region 114' can be any part of the sample surface within the target portion 114. Note that a part of each scanned target portion 114, i.e., the partial region 114', is a similar part of the sample surface for each target portion 114, for example, having a similar size and / or position within the target portion 114. Such partial processing of the sample surface can improve efficiency, for example, by improving stability, thereby improving throughput by reducing the overall time required for scanning.

[0072]

[0086] The control system 500 is configured to generate a sample surface topography map. The generated sample surface topography map optionally represents the topography of the sample surface in the reference frame of the charged particle device. Accordingly, the sample surface topography map provides information regarding the shape of the sample surface facing the charged particle device, such as changes in flatness or changes in displacement of the sample surface (e.g., deviation from an ideal plane of the sample surface), in the reference frame of the charged particle device. The control system 500 generates a sample surface topography map by analyzing a detection signal from a detector. The detection signal is detected in response to the scanning of at least a subset of the beam grid 102 and respective target portions 114 relative to each other. Accordingly, a detection signal can be provided for each of the target portions 114 scanned by the charged particle beam. By using information from the scanning of the charged particle beam itself (instead of or in addition to information from the proximity sensor 104 outside the path 103 of the beam grid 102), it becomes possible to obtain detailed information regarding the sample surface topography. The generated sample surface topography map can provide a basis for controlling the positioning of the sample 208 and / or the operation of the charged particle device more effectively than, for example, that described with reference to FIG. 9. Specifically, it is possible to improve the technique of simply positioning the sample 208 to ensure that the sample surface coincides with the focal plane 108 at the position corresponding to the proximity sensor 104 (outside the beam grid 102).

[0073]

[0087] By using information from the scanning of a charged particle beam, higher resolution information regarding the sample surface topography can be provided as compared to alternative methods based on proximity sensors. Additionally or alternatively, by using information from the scanning of the charged particle beam, i.e., the primary beam, electromagnetic interference to the focus of the primary beam can be essentially taken into account, which cannot affect the measurement by a proximity sensor. The electromagnetic interference to the focus can occur due to a feature in the vicinity of the sample 208, and this feature affects the electric field and / or magnetic field in the region through which the charged particle (e.g., the primary beam) passes, thereby affecting the trajectory of the charged particle. The feature affecting the field can be, for example, on the side of the sample 208 opposite to the side facing the charged particle beam. The way such interference affects the focusing of the beam can be the same during the scanning of the beam to generate a sample surface topography map and during subsequent scanning of the beam (e.g., during an evaluation process such as an inspection process) for processing the sample 208 using, for example, the generated sample surface topography map. During the beam scanning for generating the sample surface topography map, the same interfering electromagnetic field can be encountered as when processing the same sample 208. Therefore, by using the sample surface topography map generated by the scanning of the beam, electromagnetic interference is essentially taken into account, and the associated degradation in the quality of the focus is reduced or avoided.

[0074]

[0088] For example, in some embodiments, the control system 500 uses the generated sample surface topography map during subsequent processing of the sample 208 using the beam grid 102. Subsequent processing may include an evaluation process (e.g., an inspection process) using the beam grid 102. Subsequent processing of the sample 208 may include, for example, inspecting for defects in the sample 208. The generated sample surface topography map may be used to control the positioning of the sample 208 during subsequent processing. For example, in the situation shown in FIG. 9, the sample 208 may be positioned higher so that the portion of the sample surface in the path 103 of the beam grid 102 is within, rather than outside, the range defined by the upper limit 110 and the lower limit 112. Instead of or in addition to, the control system 500 may control the positioning of the focal plane for each of one or more of the charged particle beams of at least a portion of the beam grid 102. The position of the focal plane 108 may be determined by the potential applied to the electrodes in a charged particle device, such as the electrodes of the objective lens array 401 and / or the control lens array 250, as described above with reference to FIGS. 2-7. Accordingly, the control system 500 may adjust the position of the focal plane for each of one or more of the charged particle beams by changing the potential applied to the appropriate electrodes in the charged particle device. This may be achieved via macroelectrodes that act on all the charged particle beams so that the focal plane is adjusted in the same way for all the beams. Instead of or in addition to, the electrodes may be configured to act independently on different beams or groups of beams. For example, a strip electrode, such as an array of strip electrodes, acting on a group of beams may be provided. The group of beams may be arranged in a line of beams of the beam grid, such as parallel lines. The strip electrodes of a stack of such arrays of strip electrodes positioned along the path of the beam grid may have different relative orientations across the beam grid along the primary axis of the beam grid, which may be, for example, linear or hexagonal.The beam acts as part of a group, e.g., a line of the beam, by each array of strip electrodes, but multiple stacks of strip electrodes of the stack can be configured together such that the beam becomes a member (e.g., a line) of different groups of beams of the beam lattice in different arrays of strip electrodes. Thus, different beams of the beam lattice can act differently from another beam of the beam lattice by multiple stacks of arrays of strip electrodes (e.g., all stacks of arrays of strip electrodes). That is, the stack of arrays of strip electrodes may be capable of selectively applying different deflections to different beams of the beam lattice.

[0075]

[0089] In an embodiment having the proximity sensor 104, the control system 500 may use the generated sample surface topography map together with the output data from the proximity sensor 104 to control the positioning of the sample and / or the focal plane during subsequent processing (e.g., inspection) of the sample 208. By using such a combination of information, improved robustness / reliability is provided and / or control with finer precision becomes possible. For example, the information obtained from the proximity sensor 104 can be used to verify and / or adjust the information regarding the sample surface topography provided by the generated sample surface topography map. The sample surface topography may drift due to a change in temperature within the sample 208, for example, during a period between the implementation of the scan to generate the sample surface topography map and the subsequent processing of the sample 208. The measurement from the proximity sensor 104 can be used to update the generated sample surface topography map or apply a correction to compensate for an error in the generated sample surface topography map.

[0076]

[0090] In some embodiments, the control system 500 is configured to select a common focal plane for the charged particle beams. This can be done, for example, during calibration for an ideal sample surface that may have small variations in surface position (e.g., along the direction of the grid path) across the entire surface, for a portion of the sample surface. The common focal plane is the same for at least a portion of the charged particle beams, optionally for all of the charged particle beams. This approach reduces or avoids the need to individually control the focal plane for each of the charged particle beams, for example, by operating the electro - optical elements, such as lens elements, along each respective optical path. For example, in one embodiment, adjusting the focus of the charged particle beams (e.g., relative to the average focal plane of the beam grid) can be done only at regular intervals, for example, only at the start of processing of one sample or a number of samples or further only during maintenance of the evaluation device. Adjusting the focus of the charged particle beams in this way need not be dynamic, and such an adjustment can be referred to as calibration of the charged particle beam and the beam grid. Infrequent adjustment of the focal plane of the beam grid, e.g., non - dynamic control, may be desirable to facilitate simplification of the design of the charged particle device. That is, the charged particle device can omit having an array of individual beam correctors or any other type of corrector array. Introducing such electro - optical components into the charged particle device can add complexity, for example, when the beam grid has a large number of beams, e.g., more than 100 beams, e.g., thousands of beams, and each individual corrector requires at least one control signal. Such a beam grid can have a large field of view.

[0077]

[0091] In one embodiment, calibration of a common focal plane can be performed by adjusting the focal plane of a charged particle beam such that differences between focal planes (or focal positions or foci) of charged particle beams within a beam lattice are statistically minimized compared to an ideal focal plane (e.g., here, different beams of the beam lattice have foci at the same position along the path of the beam lattice). The control system 500 can be selected to cause subsequent processing of the sample 208 or subsequent samples processed by the beam lattice to be performed using at least a portion of the beam lattice 102, e.g., using selected beams of the beam lattice focused on the calibrated common focal plane. In one embodiment, beams having focal planes that are farther from the focal threshold than the calibrated common focal plane can be removed from the selection of beams of the beam lattice. Such subsequent samples can be processed after the sample 208 used to calibrate the common focal plane of the beam lattice, i.e., periodically during setup or e.g., during maintenance, after a set time, after sample processing time, or after processing a set number of samples. Such calibration can be performed periodically after a certain time has elapsed and / or after processing a specific number of samples, desirably to ensure stability, taking into account expected drifts in the behavior and performance of the charged particle device. For an evaluation system where calibration is periodically required, knowledge of the common focal plane can assist in determining the sample position by controlling the positioning of the sample along the beam lattice path for different focal condition settings of each target portion 114. When calibrating the common focal plane, the sample surface can be a special surface of the stage, or a surface of a sample that is processed, e.g., for evaluation such as inspection, such as the surface of a dedicated reference sample used specifically for calibration, or a sample kit having surface characteristics similar to the sample.

[0078]

[0092] In one embodiment, the control system 500 uses the generated sample surface topography map to select a common focal plane for the beam lattice 102. The common focal plane can be selected such that the common focal plane is improved or optimized. The common focal plane can have a small difference or perturbation from the focus of each beam of the beam lattice. Such a difference or perturbation can have a small, desirably negligible, effect on the common focal plane. The selected common focal plane can be selected to maximize the average quality of the focus of the charged particle beam on the sample surface (averaged across the charged particle beams within the beam lattice 102). For example, the selected common focal plane for a particular sample can be selected to minimize the sum of the differences between the position of the processed target region 114 (such as provided by the generated sample surface topography map) and the common focal plane, for example, by using the least squares method or the like. The control system 500 causes subsequent processing of the sample 208 by the beam lattice 102 to be performed using at least a portion of the beam focused on the common focal plane.

[0079]

[0093] In some embodiments, the control system uses the generated sample surface topography map to select the lattice path positions of the sample along the path of the beam lattice. In one embodiment, the lattice path position may be referred to as the Z position or Z level with reference to a Cartesian coordinate system in which the Z axis is aligned with the principal axis of the path 103 of the beam lattice 102. The lattice path position may be defined with respect to the principal axis of the path of the beams of the beam lattice 102. In another configuration, the lattice path position may be defined, for example, by the principal axis of the net or average path of the beam lattice 102 with respect to the average of the paths of the different beams of the beam lattice. Where the beam lattice has a field of view that is relatively large, for example greater than about 0.5 mm, for example 0.5 - 30 mm or 1 - 30 mm, for example 0.5 - 15 mm, compared to the probe size (cross-sectional area) of each beam and / or the surface area of the sample surface, the lattice path position may additionally have a tilt component with respect to the Z axis aligned with the principal axis of the path 103 of the beam lattice 102 (or may include a parameter of the tilt). The selected lattice path position may be selected such that the lattice path position is improved or optimized. The selected lattice path position may be selected, for example, to minimize the displacement along the principal axis of the path 103 of the beam lattice of the focal plane with respect to the sample surface. The lattice path position may be selected, for example, to maximize the average quality of the focus of the charged particle beam on the sample surface (for example, averaged across the charged particle beams within the beam lattice 102). The selected lattice path position may be selected to minimize the sum of the differences between the Z position of the processed target region 114 and the focal plane of the beam lattice, for example by using the least squares method or the like. The control system 500 positions the sample at the selected lattice path position to effect subsequent processing of the sample 208 by the beam lattice. In a configuration where the focal plane of the beams of the beam lattice is static, for example, in an evaluation device where the field of view of the beam lattice at the lattice path position is smaller, for example a small portion of the region of the sample surface, the lattice path position may be determined for the sample or for a different region of the same sample.

[0080]

[0094] Here, an exemplary method for generating a sample surface topography map using the detection signal from the detector will be described.

[0081]

[0095] In some embodiments, the control system 500 controls the sample support, the detector, and / or the charged particle device to perform the scanning of at least a subset of the beam grid 102 with respect to each respective target portion 114 under a plurality of different focus condition settings of the evaluation device. Each focus condition setting can define a different relative position between the focal plane 108 and each respective target portion 114 for each charged particle beam. Thus, each focus condition setting can change the quality of the focus on each target portion 114. The scanning of at least a subset of the beam grid 102 with respect to each respective target portion 114 under a plurality of focus condition settings includes that each charged particle beam processes all of the target portion 114 corresponding to that charged particle beam once for each of the plurality of focus condition settings. Thus, the same target portion 114 on the sample 208 is processed multiple times by the charged particle beam, each time using a different focus condition setting. Each target portion 114 can be processed sequentially (i.e., one by one) with one focus condition setting at a time using the focus condition settings. The detector can be configured to independently detect signal charged particles for each target portion 114 such that images of the plurality of target portions 114 can be generated simultaneously.

[0082]

[0096] Different focus condition settings can be provided to each target portion 114 by controlling the positioning of the sample, controlling the positioning of the focal plane of each charged particle beam, or both.

[0083]

[0097] For example, in some embodiments, the control system 500 provides a plurality of different focus condition settings by controlling the positioning of the sample support relative to the charged particle device in at least one degree of freedom. The at least one degree of freedom may include the position of the sample support along the path 103 of the beam lattice 102 and / or the orientation of the sample support such as an inclination (rotation about an axis) with respect to a direction orthogonal to the path 103 of the beam lattice 102.

[0084]

[0098] FIG. 11 schematically shows four charged particle beams 121-124 of a beam lattice 102 having a common focal plane 108 (in this example, the position of the focal plane 108 is the same for all of the beams 121-124). Three exemplary positions of a portion of the sample 208 are shown, which are labeled 208', 208'', and 208''', respectively. Each position corresponds in this case to a different exemplary focus condition setting realized by positioning the sample at a different respective Z position. A portion of the sample within the path of the beam lattice 102 is inclined with respect to an axis orthogonal to the main axis of the beam lattice 102. Position 208' is the farthest from the detector module 402 along the path of the main axis, and position 208''' is the closest to the detector module 402. The sample 208 may be positioned with respect to the path of the beam lattice 102 corresponding to the main axis of the beam lattice with reference to a point on the sample surface along the path of the beam lattice, for example a reference point. That portion of the sample 208 has a gradient (i.e., is inclined) to represent the non-flatness of the sample surface.

[0085]

[0099] In this simplified example, in the case of a focus condition setting where the sample 208 is at position 208', it can be seen that the rightmost beam 124 is well focused on the target portion 114 of the sample surface corresponding to the beam 124. The target portion 114 processed by the beam 124 under this focus condition (i.e., when the sample 208 is at position 208') will generate an image having characteristics showing a high quality of focus (e.g., high contrast). In contrast, the target portions 114 processed by the beams 123, 122, and 121 will generate images having a gradually decreasing quality of focus (e.g., gradually decreasing contrast). This information suggests that the topography of the sample surface has a gradient either upward or downward along a line (e.g., a line passing through points defined by the intersections between the sample and the respective beam 121 - 124 paths passing through the target portion 114) corresponding to the target portions 114 of the beams 121 - 124. In the case of a focus condition setting where the sample 208 is at position 208'', the leftmost beam 121 is well focused on the target portion 114 of the sample surface corresponding to the beam 121. The target portion 114 processed by the beam 121 under this focus condition (i.e., when the sample 208 is at position 208'') will generate an image having characteristics showing a high quality of focus (e.g., high contrast). In contrast, the target portions 114 processed by the beams 122, 123, and 124 will generate images having a gradually decreasing quality of focus (e.g., gradually decreasing contrast).

[0086]

[0100] Information from two different focus condition settings confirms the presence of a gradient and further provides the direction (or sign) of the gradient. In this case, the gradient should be rising from left to right. The third focus condition setting shown, where the sample 208 is at position 208''', can be used to improve or confirm the measurement of the topography of the sample surface. In this case, all of the target portion 114 processed by the beams 121 - 124 is out of focus, but the degree of out-of-focus still varies between the different target portions 114. If a change in the quality of focus is detectable, for example, as a measurable difference in contrast in the image derived from each target region 114, information regarding the topography of the sample surface can be obtained.

[0087]

[0101] Instead of or in addition, in some embodiments, the control system 500 provides a plurality of different focus condition settings by controlling the positioning of the focal plane of each charged particle beam of at least a subset of the beam lattice 102 with respect to the charged particle device.

[0088]

[0102] Figures 12 to 15 schematically show how the focal planes 108 of the same four charged particle beams 121 to 124 in FIG. 11 can be changed to provide different focal condition settings. In this case, each of the different positions of the focal plane 108 corresponds to a different respective focal condition setting. In FIG. 12, the focal plane 108 is closest to the charged particle device, and in FIGS. 13 to 15, it gradually moves away and is at different positions along the path of the beam lattice 102 with respect to the charged particle device 41 and the sample 208, for example. In FIG. 15, the focal plane 108 is farthest from the charged particle device. The sample 208 is in the same position and orientation with respect to the charged particle device for all four focal condition settings shown in FIGS. 12 to 15. As described for the configuration of FIG. 11, a part of the sample 208 is shown to have a gradient to represent non-flatness. In this example, when the focal condition setting of FIG. 12 is applied, it can be seen that the rightmost beam 124 is best focused on the sample surface, and the beams 123, 122, and 121 gradually have worse focusing quality. When the focal condition setting of FIG. 13 is applied, the beam 123 is best focused, the beams 122 and 124 have worse focusing quality, and the beam 121 has the worst focusing quality. When the focal condition setting of FIG. 14 is applied, the beam 122 is best focused, the beams 121 and 123 have worse focusing quality, and the beam 124 has the worst focusing quality. When the focal condition setting of FIG. 15 is applied, the leftmost beam 121 is best focused, and the beams 122, 123, and 124 gradually have worse focusing quality.

[0089]

[0103] In this example, each focus condition setting optimally focuses a different one of the beams 121 - 124 on the sample surface. The optimal focusing can be detected as described above by evaluating an image derived from the processed target portion 114. For example, an image derived from the beam at the optimal focus may have the best contrast. For example, if the distance from the charged particle device along the path of the beam lattice, such as the principal axis of the beam lattice, to the focal plane 108 is known for each focus condition setting, this technique enables mapping the topography of the sample surface or at least a part of the sample surface. In the example of FIGS. 12 - 15, it is possible to obtain the value of the Z position of the target portion 114 relative to the principal axis of the path of the beam lattice, for example, corresponding to each of the four beams 121 - 124. The Z position of each target portion 114 can be derived from the position of the focal plane 108 that provides the highest quality focus for the beam corresponding to the target portion 114.

[0090]

[0104] Two different techniques for varying the focus condition setting to determine the topography map of the sample have been described above. In the configuration described with reference to FIG. 11, the different focus condition settings are achieved by moving the sample. In the configuration described with reference to FIGS. 12 - 15, the different focus condition settings are achieved by moving the focal plane of the beam lattice, for example, relative to the sample. These two techniques can be used as alternative forms. In a different embodiment, the different techniques are complementary and can be used in combination.

[0091]

[0105] Analyzing the detection signal from the detector can include calculating a metric that represents the quality of focus during the processing of each target portion 114 for each focus condition setting. In some embodiments, an image of the target portion 114 is derived from the detection signal (e.g., using an image acquirer as described above). In such cases, the metric can include a representation of the quality of focus derived from the image. For example, the metric can include a contrast level. The contrast level can be calculated by comparing the luminance in different regions of the derived image, for example, between a relatively dark (low luminance) region and a relatively bright (high luminance) region. The metric can include a measure of edge sharpness, such as a measure of the maximum rate of luminance change in the image, as a function of position along a path passing through boundaries between relatively dark and relatively bright features, such as adjacent regions defined by different pixels or groups of pixels in the image.

[0092]

[0106] In some embodiments, the control system 500 generates a sample topography map by identifying an optimal focus condition setting from a plurality of different focus condition settings for each of the processed target portions 114 of the sample surface. By identifying the optimal focus condition settings for different target portions 114, the focus plane and / or the position of the sample 208 where the focus plane and the sample surface are closest and coincide are identified, thereby providing information regarding the topography of the sample surface.

[0093]

[0107] In some embodiments, the control system 500 is configured to import an externally derived topography map. The externally derived topography map can be treated as data associated with a sample when the sample is transferred between systems and processes. The externally derived topography map is data that is part of a sample data set, for example, the metadata of the sample. The externally derived topography map represents the topography of the sample surface measured using an external device. The external device does not form part of the evaluation apparatus. The external device can include an optical evaluation device (or apparatus) or a lithography device (or apparatus). Instead or in addition, the evaluation apparatus can include an optical measurement system configured to measure a topography map of at least a part of the sample surface. The measured topography map represents the topography of the sample surface. Instead or in addition, the control system 500 can be configured to receive a sample support topography map representing the topography of the sample support. The control system 500 can use the externally derived topography map, and / or the measured topography map, and / or the sample support topography map to select a subset of the charged particle beam. As described above, for example, the subset can avoid regions on the sample surface that have been damaged or have local topography that deviates excessively from the average topography, for example, regions with surface displacements away from the net plane of the sample surface and exceeding a threshold such as a focus threshold. Instead or in addition, the externally derived topography map, and / or the measured topography map, and / or the sample support topography map can be used to select one or more of the focus condition settings used during the generation of the sample topography map. For example, the externally derived topography map, and / or the measured topography map, and / or the sample support topography map can be used to provide a rough topography map that roughly indicates the position where the sample surface is expected to be, and the focus condition setting is selected to enable fine adjustment.The selected focus condition setting can be such that it provides a plurality of positions of the focal plane with respect to the expected positions of the sample surface within each target area 114 within a small range, enabling fine adjustment without overly reducing throughput. As described above, this can be achieved, for example, by using the actuation stage 209 to adjust the sample position relative to the charged particle device 102, for example relative to (e.g., along) the grating path, and / or by controlling the focal plane of the beam grating, for example by adjusting a common focal plane, for example by adjusting the focal plane for all beams of the beam grating, and / or by controlling the individual foci of the beams of the beam grating.

[0094]

[0108] In some embodiments, the control system 500 uses an externally derived topography map in combination with the output data from the proximity sensor 104 to process the sample 208. The control system 500 can, for example, use the externally derived topography map and the output data from the proximity sensor 104 to process the sample 208 using the beam grating 102 while controlling the positioning of the sample 208. This approach can be implemented with or without generating a sample surface topography map by scanning the target portion 114 as described above. Using the output data from the proximity sensor, the position of the sample relative to the path of the beam grating 102 can be determined by referring to the externally derived topography map. Since the output data of the proximity sensor includes measurement information of the sample relative to the path of the beam grating and thus measurements of the sample position, the output data can be used to determine the position of the sample surface relative to the beam grating and to correct any error (or difference) at some positions of the sample relative to the path of the beam grating determined by the externally derived topography map based on the output information from the proximity sensor.

[0095]

[0109] In some embodiments, the control system 500 receives a sample support topography map. The sample support topography map represents the topography of the sample support. The sample support topography map can be measured by an external device or evaluation apparatus. In the latter case, the sample support topography map can be generated by directly measuring the sample support topography, desirably with no sample 208 at a predetermined position of the sample support, and preferably before the sample support supports the sample 208. This measurement can be performed using an optical measurement system, a proximity sensor 104, and / or a beam grating, and / or using the measured topography map. Alternatively, the sample surface topography map can be generated for a plurality of different samples and / or for rotations of a plurality of different samples such that the contribution from the sample itself to the topography of the sample surface facing the charged particle device can be subtracted or averaged, thereby making it possible to derive the contribution of the sample support to the topography of the sample surface. The control system 500 can use the sample support topology map as a calibration for generating a sample surface topology map. In one embodiment, the positions in the sample support topology map are fed forward to determine the same positions in the sample surface topology map. The control system can control the sample support based on the positions in the sample support topology map to process respective target positions at the same positions within the sample surface topology map.

[0096]

[0110] The topography of the sample support can include the topography of the surface of the sample support that contacts the sample 208 when the sample 208 is supported by the sample support. Thus, the topography of the sample support can contribute to the topography of the sample surface facing the beam grid 102. The topography of the sample surface facing the beam grid 102 can be determined by a combination of the topography of the sample 208 and the topography of the sample support. Thus, a sample support topography map (regardless of whether received from a device external to the evaluation apparatus or measured by the evaluation apparatus etc.) can be used to calibrate the sample surface topography map, and as a result, the sample surface topography map provides a more accurate evaluation of the topography of the sample surface facing the beam grid 102. Such a more accurate estimation of the topography of the sample surface enables improvement in the control of the focus of the beam grid 102. Thus, the sample surface topography map can be calibrated using the sample support topology map to generate a calibrated topography map, and the positioning of the sample position can be controlled using the calibrated topography map. This method can be implemented with or without generating a sample surface topography map by scanning the target portion 114 as described above.

[0097]

[0111] In some embodiments, the position in the sample support topography map (regardless of whether received or generated by the evaluation device) is fed forward to determine the same position in the sample surface topography map. The control system 500 controls the positioning of the sample support, e.g., the sample, with respect to the path of the beam lattice to process each target portion 114 of the sample surface that is at the same position in the sample surface topography map as in the sample support topography map. Thus, when processing each target portion 114, the control system 500 can control the positioning of the sample support, i.e., each target portion 114, based on the position in the sample support topography map that is the same as the position in the sample surface topography map.

[0098]

[0112] In some embodiments, the control system 500 can receive the sample support topography map as described above. In this case, the control system 500 can additionally use the sample support topography map to control the positioning of the sample 208 during processing of the sample 208. As described above, the generated sample surface topography map can be calibrated using the sample support topography map to generate a calibrated topography map. Then, the positioning of the sample can be controlled using the calibrated topography map.

[0099]

[0113] In some embodiments, as described above, the control system 500 receives a sample support topography map, and the control system uses the received sample support topography map in combination with the output data from the proximity sensor 104 to process the sample 208. The control system 500 may, for example, use the received sample support topography map and the output data from the proximity sensor 104 to process the sample 208 using the beam grid 102 while controlling the positioning of the sample 208. This technique may be implemented with or without generating a sample topography map by scanning the target portion 114 as described above. The positioning of the sample may be achieved by determining the position of the sample within the sample support topography map using the output data from the proximity sensor 104. The positioning of the sample may be achieved by calibrating, correcting, and / or optimizing the position of the sample determined by referring to the sample support topography map using the output data from the proximity sensor 104.

[0100]

[0114] In some embodiments, control system 500 includes an optical measurement system configured to measure a topography map representing the topography of the sample surface. The optical measurement system may include one or more light sources operable at one or more wavelengths of light configured to direct a beam on the sample surface for detection by one or more sensors. The one or more sensors may be configured to detect light from the one or more light sources reflected from the sample surface. The optical measurement system may include a linear array including the one or more light sources and one or more detectors. The linear array may preferably be dimensioned to extend preferably in the sensing direction across the maximum dimension of the sample. In one embodiment, the arrays of light sources and sensing elements are configured relative to the sample support such that the optical measurement system processes the sample surface, preferably the entire sample surface, when the sample moves in the scanning direction relative to the linear array such that the sample preferably makes an angle with the sensing direction. The apparatus further includes a detector configured to detect signal charged particles emitted from the sample and provide an output.

[0101]

[0115] The optical measurement system can operate to measure the sample surface by moving the sample surface and the linear array relative to each other. Then, a topography map can be generated. During the measurement of the sample surface using the optical measurement system, the sample can be on the sample support, such as when moving the sample along the path of the beam lattice between the unload position (e.g., when placing the sample on the sample support) and the evaluation position. The control system 500 can use the measured topography map to control the positioning of the sample 208 during the processing of the sample 208 by the beam lattice. This method can be implemented with or without generating a sample topography map by scanning the target portion 114 using the beam lattice 102 as described above. The map derived from the optical measurement system can generate a rough map of the entire sample surface or at least one or more selected regions. To generate a surface map with a higher resolution than the rough map of a part (or even the entire sample surface) or a part of the selected region of the sample surface, another measurement system, such as a measurement using the beam lattice, can be used. Alternatively or in addition, a rough map of a part or the whole of the sample surface can be obtained by measuring the change in the size of the gap on the sample surface by measuring each change in air pressure. In one embodiment, the rough map is defined for points spaced at a distance in the range of about 2 - 20 mm, for example, about 10 mm. The surface map with a higher resolution can determine the surface map information for all the beams and thus has a spatial resolution equivalent to the pitch between the beams. Thus, the spatial resolution can be in the range of about 50 - 200 micrometers. In embodiments where the surface map information is obtained only for a subset of the beams, the spatial resolution may be lower. For example, if 25% of the beams are used, the pitch is doubled. The spatial resolution can be in the range of about 100 - 400 micrometers. The number of beams used to determine the topography map can be selected based on the accuracy required for the use case under consideration.

[0102]

[0116] In an embodiment having the proximity sensor 104, the control system 500 may be configured to generate a sample surface topography map using the proximity sensor 104. For example, the control system 500 controls the sample support and, while moving the sample 208 relative to the charged particle device over a range of positions and / or orientations, measures the respective changes in the distance between the proximity sensor 104 and the sample surface using the proximity sensor 104, thereby generating a sample surface topography map. If the principal axis of the beam grid 102 is, for example, the Z-axis of a Cartesian coordinate system, in this case, the movement of the sample 208 may involve movement mainly in a plane orthogonal to the Z-axis, for example, in the XY plane. As a result, the proximity sensor 104 can scan over, for example, most or all of the sample surface facing the charged particle device. The generated sample surface topography map can be used to control the position and / or orientation of the sample 208 during the processing of the sample 208 by the beam grid 102. The generated sample surface topography map can be used to correct the setpoint for determining the position of the sample 208 with respect to the output data from the proximity sensor 104. The orientation may be the tilt of the sample and can be, for example, a rotational displacement of the sample surface away from a plane orthogonal to the beam path of the beam grid (e.g., the principal axis of the beam grid), desirably about an axis within the orthogonal plane. The position or orientation of the sample 208 may be controlled to move over successive ranges of different positions and / or orientations during processing by the beam grid.

[0103]

[0117] Several different methods for generating a sample topography map are described herein, and different techniques may be used individually or in combination. The selection of a technique or combination of techniques may depend on the desired characteristics of the sample topography map for the intended application. For example, if a maximum applicable range of the sample surface is desired, a technique or combination of techniques that has a coarser resolution and / or that depends on correction or calibration, e.g., a sample topography map that depends on a sample map imported from outside or generated from an optical measurement system, and that provides a useful map will be selected. By combining techniques that can provide a high resolution for at least a portion of the sample surface where a high resolution is required, it becomes possible to achieve the required accuracy in the sample topography map without or with a reduced impact on throughput. Further, by considering the sample support topography map, an improved application of the sample map of an externally generated sample becomes possible, and the possibility of applying data regarding the sample surface, such as a sample surface topography map, for subsequent processing of the sample in different apparatuses is improved.

[0104]

[0118] The non-flatness of the sample can be extreme in some cases, and there may be regions on the sample or even the entire sample that cannot be processed without problems by the charged particle device. This can be caused by the presence of particles between the sample and the sample support (backside defects) or by other defect mechanisms or the topography of the extreme sample or sample table. In one embodiment, due to previous processing, for example, when determining the three-dimensional structure of the sample surface, the stress applied to the sample can bend or flex the sample away from the plane of the ideal sample. One or more regions at the periphery of the sample can curve upward. To account for this situation, a sample surface topography map can be obtained (using any of the above methods or other methods), and regions on the sample surface topography map can be annotated to provide information regarding the suitability of the regions to undergo the inspection process by the beam grid. Different surface portions of the sample surface can be classified according to the arrangement of the surface relative to the sample support and / or the gradient or inclination of the surface portion. For example, a first subset of regions can be annotated as being fully suitable for inspection, a second subset of regions can be annotated as being partially suitable for inspection (or suitable when preventive measures are taken), and a third subset of regions can be annotated as being unsuitable for inspection. Thus, the first subset of regions or class of regions can include regions where the sample topography is relatively flat, or the displacement change of the sample surface is within a first threshold such that it is possible to control the positioning of the sample 208 and / or the focal plane to achieve an acceptable focus quality for substantially all of the regions in the first subset of regions. The second subset of regions or second class of regions can include regions where the sample topography is more difficult but not so severe that beam grid processing becomes impossible for at least some of the regions in the second subset of regions. The second class of regions has a sample surface with a displacement change that is at or above the first threshold and within a second threshold.A third subset of regions or a third class of regions may include regions that are not useful and / or safe because the sample topography is too severe to be processed by the beam grid. The third class may include surface portions having a displacement change at or above a second threshold.

[0105]

[0119] Annotated sample surface topography maps (or classified surface maps) can be used in various ways. In one approach, the evaluation device can selectively inspect only the regions of the sample annotated as being in the first subset or only the regions annotated as being in the first subset or the second subset. This can be achieved by using only a portion of the beam grid (i.e., only a subset of the available charged particle beam) to process the sample 208. The particular subset of the charged particle beam used can change such that only the selected regions (in the first subset and / or the second subset) are processed as the intersection of the beam grid and different regions of the sample changes. Alternatively, all of the charged particle beams of the beam grid can be used and data corresponding to the unselected regions (in the second subset and / or the third subset) can be discarded. In some use cases, it is not necessary to inspect the entire sample. For example, in reticle mask inspection, it is usually not necessary to inspect the entire substrate. A subset of dies may be sufficient. Inspection of regions near the edges of the sample can provide particularly useful information, and the annotated sample surface topography map allows for the rapid and easy identification of sufficiently flat areas for efficient inspection.

[0106]

[0120] In another approach, where regions of interest that would not be in good focus will be processed by a portion of the beam grid (due to difficult topography as shown in the annotated sample surface topography map), the regions of interest can be processed multiple times with different focus condition settings. In connection with the above description, different focus condition settings can include different sample positions and / or different focal plane positions. (The sample position can be the position of the sample surface relative to the grid beam path, desirably the position of the sample surface across the entire grid beam path. The focal plane position can be the position of the plane common to the foci of the beam grid or at least the selected beams of the beam grid). The data thus obtained can be combined to provide improved focus across the entire field of view. In one focus condition setting, regions of poor focus can become regions of better focus in other focus condition settings and vice versa. By combining the data obtained from processing the regions of interest multiple times, it becomes possible to select the best version of each sub-region. For example, an image of each sub-region with the best focus (e.g., the highest contrast) can be selected from the multiple images of that sub-region provided by processing the region of interest with multiple focus condition settings).

[0107]

[0121] In some configurations, the sub-regions in the region of interest can be processed multiple times by different charged particle beams of the beam grid. For example, the processing of the sample by the beam grid can be repeated multiple times by displacing the beam grid by one or more beam pitches. Selecting the images with the best quality for each sub-region and stitching them together can provide a better quality overall image that can be achieved using only a single scan for each sub-region. This approach compensates for the change in the position of the focal plane between different charged particle beams in the beam grid at the expense of lower throughput.

[0108]

[0122] All data generated in relation to a sample, such as characteristics of the sample surface like a rough map and / or a high-resolution map of the sample surface, can be added to the sample dataset, regardless of whether it pertains to the entire sample surface or a part of the sample surface. The data generated in relation to the sample can be added to the sample dataset as the sample is processed. The sample can be transferred to a further manufacturing process together with the sample dataset. The exported sample dataset may be larger than when the sample was introduced into the evaluation device.

[0109]

[0123] FIG. 16 is a schematic diagram of a further exemplary charged particle device 41 for use in an evaluation apparatus. The charged particle device 41 can be used in combination with any of the embodiments described herein, for example, in place of any of the charged particle devices 41 described above with reference to FIGS. 3 and / or 7. In this example, the charged particle device 41 includes an electron source 201, a beam forming aperture array 502, a condenser lens 504, an electron source conversion unit 506, an objective lens 508, and a sample 208. The electron source 201 and the sample 208 can take any of the forms described above, for example, with reference to FIGS. 2, 3, and 7. The electron source 201, the beam forming aperture array 502, the condenser lens 504, the electron source conversion unit 506, and the objective lens 508 can be aligned along the primary electron optical axis 510 of the charged particle device 41. The electron source 201 generates a primary electron beam 512 using an electron source crossover 514. In one embodiment, the beam forming aperture array 502 forms beams 521, 522, 523 from the primary beam 512 as a beam lattice. Different beams can have different paths, which can be called beam paths. In such a configuration, the beam forming aperture array 502 can reduce the current of charged particles projected beyond the beam forming aperture array 502 so as to reduce the risk and / or degree of Coulomb interaction between different beams and the resulting aberrations. Although a three-beam line is shown, the beam forming aperture array 502 can be configured to form a two-beam line or a line with more than three beams, such as a four-beam line or a five-beam line, or more beams as a beam lattice, for example. The beam forming aperture array 502 can also be configured to form a plurality of lines of beams, thereby forming an array of beams that can be called a beam lattice. For example, the beam forming aperture array 502 can have at least two axes and be configured to form an array of beams having an integer number of beams per axis. For example, the array of beams can be a two-dimensional array of n×m beams, where n and m can be the same or different integers, such as a 3×3 array of beams, a 3×4 array of beams, or a 5×5 array of beams.

[0110]

[0124] The light - collecting lens 504 is configured to converge, change, or redirect the paths of the beams 521, 522, 523, and desirably collimate the paths of the beams so that they are substantially parallel to each other and / or to be incident substantially perpendicular to the flat surface of the electron - source conversion unit 506 over the entire paths of the beams 521, 522, 523.

[0111]

[0125] The electron - source conversion unit 506 may include a beam - limiting aperture array 531 that defines apertures configured to laterally limit each of the beams 521, 522, 523. In one configuration for limiting the beam, the beam - limiting aperture array may generate additional beams. In such a configuration, the beam - forming aperture array 502 has a primary function of reducing the current of charged particles projected beyond the beam - forming aperture array 502 so as to reduce the risk and / or degree of Coulomb interaction between different beams. Thus, when the beam is advanced to the beam - limiting aperture array 531 on the down - beam side, the beam - forming array 502 does not need to generate all the beams of the beam lattice. For example, if the apertures in the beam - forming aperture array 531 have a low - symmetry cross - section such as a non - circular shape, the beam - limiting aperture array 531 can generate more beams. Such a shape can be beneficial for reducing the current considering the rotational effect that the magnetic light - collecting lens has on the path of the beam from the beam - forming aperture array around the mid - point of the beam lattice. As a result, the beams generated by the beam - forming aperture array may be incident on one or more of the apertures of the beam - limiting aperture array 531. In such a configuration, the beams generated and limited by the beam - limiting aperture array 531 may exhibit the characteristics of the beams 521, 522, 523 of the beam lattice described above.

[0112]

[0126] The electron source conversion unit 506 may include an image forming element array 532 including an array of micro deflectors (i.e., micro deflector array) configured to deflect the beams 521, 522, 523 of the beam lattice toward the axis 510. The deflected beams 521, 522, 523 may form a virtual image of the electron source crossover 514 on the sample 208. In one configuration, the micro deflector has four or more deflector electrodes around each beam path. The micro deflector (e.g., deflector electrode) may be controllable to have a focusing function for each beam of the beam lattice, and / or the electron source conversion unit 506 may additionally have a microlens array having microlenses for each beam of the beam lattice.

[0113]

[0127] The electron source conversion unit 506 may include an aberration compensator array 534 configured to compensate for aberrations in the beams 521, 522, 523. The aberration compensator array 534 may be configured to compensate for, for example, field curvature and / or spherical aberration.

[0114]

[0128] The electron source conversion unit 506 may include a pre-bending micro deflector array 533 configured to bend the paths of the beams 521, 522, 523 on the up-beam side of the beam limiting aperture array 531 so that the paths of the beams 521, 522, 523 are incident substantially perpendicularly on the beam limiting aperture array 531.

[0115]

[0129] The beam limiting aperture array 531, the image forming element array 532, the aberration compensator array 534 and / or the pre-bending micro deflector array 533 may include multiple layers of sub-beam manipulation devices, some of which may be in the form of an array, such as micro deflectors, microlenses and / or micro spherical aberration correctors.

[0116]

[0130] In the illustrated example, the objective lens 508 includes a magnetic lens that macroscopically acts on the beam to focus the beam onto the sample 208. In other embodiments, the objective lens 508 may include an electrostatically realized objective lens array, or a combination of a magnetic lens and an electrostatic lens may be used, for example, a combined objective lens that includes a magnetic objective lens controlled for its desired setting, and adjustment macroelectrodes positioned therein, around it, on the up-beam side and / or on the down-beam side to adjust, optimize, perturb, and / or correct the lens setting of the combined objective lens. Considering that the magnetic objective lens may be controllable between settings by a supply current having a slow response, the use of electrostatic adjustment electrodes may enable rapid adjustment of the setting of the combined lens.

[0117]

[0131] Accordingly, the electro-optical adjustment of the beam focus setting can be achieved for all beams of the beam lattice by adjusting the objective lens, for example, by adjusting the adjustment electrodes of the combined objective lens. By controlling one or more respective elements of the electron source conversion unit 506 to adjust the focus of the beam, the adjustment of the focus setting of one beam can be achieved, for example, by adjusting each microlens of the microlens array and / or each microdeflector of the microdeflector array.

[0118]

[0132] In the example described above with reference to FIGS. 11 to 15, the sample surface topography map is generated by processing the target portion 114 with a plurality of different focus condition settings. The different focus condition settings can be achieved by changing the position of the sample 208 along the grid path (for example, to change the Z position of the sample 208) and / or by changing the position of the focal plane of each beam (for example, to change the Z position of the focal plane).

[0119]

[0133] Figures 17 and 18 illustrate techniques that can be used in place of or in addition to the techniques of FIGS. 11-15. In this type of embodiment, the scanning of at least a subset of the beam lattice for the target portion 114 is performed using a plurality of beams focused on different focal planes. The different focal planes are at different distances from the charged particle device, for example, different Z positions and / or different separation distances from an element of the charged particle device positioned closest to the sample 208 (e.g., the objective lens array 401, the detector module 402, or the objective lens 508). FIG. 17 schematically shows an exemplary distribution of different focal planes of the beams in the beam lattice, including an array of beams that is a 5×5 array as shown. Five different focal planes are labeled F1-F5 and are schematically shown in a side view on the array. The horizontal dashed lines in the side view represent the respective different positions of the focal planes along the Z axis. As illustrated in FIG. 17, the beam lattice can include, for example, rows of beams (e.g., aligned along X in FIG. 17) and / or columns of beams (e.g., aligned along Y in FIG. 17) of a rectangular lattice. Optionally, the beam lattice can include a third axis, e.g., a line of beams. The angle between the axes, e.g., the angle between the line of beams and a column or row of beams, can be substantially the same, e.g., 60 degrees. In some embodiments, the scanning is performed on two or more, optionally all, of the beams in each row focused on different focal planes. In the example of FIG. 17, each row has one beam focused on five different focal planes F1-F5. In some embodiments, the scanning is performed on two or more, optionally all, of the beams in each column focused on different focal planes. In the example of FIG. 17, each column has one beam focused on five different focal planes F1-F5. Each of one or more of the target portions 114 is processed at different respective times by two or more of the plurality of beams focused within different focal planes during the scan. The distance between the different focal planes can be selected based on the use case, e.g., the expected size of the defect, e.g., the expected size of the electromagnetic interference with respect to the focus, and / or the expected range of non-flatness in the sample and / or the sample support.

[0120]

[0134] The target portion can be processed one by one in sequence by beams focused on different focal planes. In some embodiments, the scanning involves providing relative movement between the grid path of the beam grid along a path having a portion parallel to the row and the sample surface. Thus, the scanning can involve relative movement parallel to the X axis in the orientation shown in FIG. 17. Such scanning enables each of one or more of the target portions 114 to be processed by each of the beams in one of the rows. For example, the target portion 114 at the Y position aligned in one of the rows can be processed by each of the beams in that row. Thus, the target portion 114 can be processed separately by the beam focused within the focal plane F1, the beam focused within the focal plane F2, the beam focused within the focal plane F3, the beam focused within the focal plane F4, and the beam focused within the focal plane F5. Thus, five different images of the target portion 114 can be obtained during the scanning.

[0121]

[0135] As described above, for example, by calculating a metric representing the quality of focus for each image, such as the contrast level, it is possible to determine which of the focal planes F1 to F5 provides the best quality of focus, thereby providing relevant information for generating a sample surface topography map and enabling future processing of the target portion 114 (during an evaluation process such as an inspection process) to be performed with a high-quality focus. Accordingly, the control system 500 can be configured to generate a sample surface topography map by identifying, for each target portion 114 of the sample surface processed by two or more beams focused on different focal planes, the focal plane that provides the best focus on the target portion. Using the generated sample surface topography map, it is possible to control how the beams of the beam lattice are focused in subsequent evaluation processes performed on the sample 208. For example, the electron optical lens can be controlled to change the position of the focal plane of each individual beam, or an optimal common focal plane can be determined for all of the beams using the generated sample surface topography map. As described above, this approach can provide a higher resolution control of the focus and / or essentially compensate for electromagnetic interference in the vicinity of the sample 208. The sample surface topography map can be obtained, for example, once for each sample 208 as part of an initial setup procedure, or can be performed multiple times for each sample 208, for example during the processing of different layers on the sample 208.

[0122]

[0136] In some embodiments, the scanning includes providing relative movement between the grid path of the beam lattice and the sample surface along a path having a portion parallel to the columns. Accordingly, the scanning can involve relative movement parallel to an axis such as the Y-axis in the orientation shown in FIG. 17. Similar to the movement along the rows, such scanning enables each of one or more of the target portions 114 to be processed by each of the beams in one of the columns.

[0123]

[0137] The above process is schematically shown in FIG. 18. Each horizontal waveform line represents the same portion of sample 208 having a sample surface topography in which the Z position (height) varies. A row of five beams focused within five different focal planes (e.g., corresponding to the five focal planes F1 - F5 shown in FIG. 17) moves relative to sample 208, for example, along the X direction (from left to right in the figure). Each horizontal line indicates a different position of the row of beams relative to sample 208 during this movement. Thus, the uppermost horizontal line represents the earliest time and the lowermost horizontal line represents the latest time. The vertical dashed boxes 541 - 545 surround sets of beams that process the same target portion 114 of sample 208, indicating that each of the target portions can be processed separately using beams focused at each of the five different focal planes F1 - F5 (the processing is performed sequentially at different respective times). It will be understood that the selection of the five different focal planes and the array of beams, e.g., a 5×5 array of beams, is merely exemplary. In other configurations, smaller or larger arrays of beams and / or non - square arrays having, for example, additional axes, can be used, for example, with a corresponding different number of different focal planes (e.g., for rectangular arrays of beams having different numbers of beams in rows and columns and configurations having additional axes and degrees of freedom available). In some embodiments, the beams can be controlled in groups such that all of the beams within each group are controlled to be focused at the same focal plane and the beams within different groups are controlled to be focused at different focal planes relative to each other.

[0124]

[0138] In an embodiment explicitly described with reference to a device having an electron optical design shown in and described with reference to FIG. 16, it should be noted that the methods and operating procedures can be applied to a device having an electron optical design shown in and described with reference to FIGS. 3 and / or 7. Thus, a beam lattice implementing an embodiment of the present invention can have a limited number of beams, for example, when having different beams (or groups of beams) of the beam lattice at different focus settings, such as 25 beams which is a 5×5 array of beams, and can have hundreds or even thousands of beams, for example, 4, one hundred, one thousand or even tens of thousands of beams.

[0125]

[0139] A reference to a component or a system of components or elements being controllable to operate a charged particle beam in a particular way includes configuring a controller or control system or control unit to control the component to operate the charged particle beam in the described way and, optionally, using other controllers or devices (e.g., a voltage supply and / or a current supply) to control the component to operate the charged particle beam in this way. For example, the voltage supply can be electrically connected to one or more components including, by way of non-limiting list, the control lens array 250, the objective lens array 241, and the detector array 240, to apply a potential to the components.

[0126]

[0140] References to up and down, top and bottom, and upper and lower etc. are to be understood as referring to directions parallel to the (not always, but usually vertical) up-beam and down-beam directions of the charged particle beam impinging on the sample 208. Thus, references to up-beam and down-beam are intended to refer to directions with respect to the beam path independent of any current gravitational field.

[0127]

[0141] The electron optical device described herein can take the form of a series of aperture arrays or electron optical elements arranged in an array along a beam path or a multi-beam path. Such electron optical elements can be electrostatic. In one embodiment, for example, all electron optical elements from a beam limiting aperture array to the final electron optical element in the beam path in front of the sample can be electrostatic and / or can be in the form of an aperture array or a plate array. In some configurations, one or more of the electron optical elements are manufactured as microelectromechanical systems (MEMS) (i.e., by using MEMS manufacturing techniques). The electron optical elements can have magnetic and electrostatic elements. For example, a composite array lens can include a multi-beam path within a magnetic lens by upper and lower pole plates and can be characterized by a macro magnetic lens arranged along the multi-beam path. An array of apertures of the beam paths of the multi-beams can be present within the pole plates. Electrodes can be present above, below, or between the pole plates to control and optimize the electromagnetic field of the composite lens array.

[0128]

[0142] An evaluation device, tool, or system according to the present disclosure can include a device for performing a qualitative measurement of a sample (e.g., pass / fail), a device for performing a quantitative evaluation of a sample (e.g., the size of a feature), or a device for generating an image of a map of a sample. Examples of evaluation devices, tools, or systems are inspection tools (e.g., for identifying defects), review tools (e.g., for classifying defects), and measurement tools or tools capable of performing any combination of evaluation functions associated with inspection tools, review tools, or measurement tools (e.g., measurement inspection tools).

[0129]

[0143] The functions provided by a controller, or a control system, or a control unit can be computer-implemented. Any suitable combination of elements can be used to provide the necessary functions, including, for example, a CPU, RAM, SSD, motherboard, network connection, firmware, software, and / or other elements known in the art that enable the required computing operations to be performed. The required computing operations can be defined by one or more computer programs. The one or more computer programs can be provided in the form of a medium storing computer-readable instructions, optionally a non-transitory medium. When the computer-readable instructions are read by a computer, the computer performs the required method steps. The computer can be configured in a distributed computing system having a plurality of different computers connected to each other either within a built-in unit or via a network.

[0130]

[0144] Although the present invention has been described in connection with various embodiments, other embodiments of the present invention will become apparent to those skilled in the art upon consideration of the specification and implementation of the invention disclosed herein. The specification and examples are to be regarded as merely illustrative, and it is intended that the true scope and spirit of the invention be indicated by the following claims and clauses.

[0131]

[0145] The following clauses are provided.

[0132]

[0146] Clause 1. An evaluation apparatus for evaluating a sample using a plurality of charged particle beams, comprising: a sample support configured to support a sample having a sample surface; a charged particle device configured to project a beam lattice of the plurality of charged particle beams toward the sample along a lattice path of the beam lattice; a detector configured to detect signal charged particles from the sample and generate a detection signal when the signal charged particles are detected; and a control system configured to control the sample support, the charged particle device, and / or the detector to scan at least a subset of the beam lattice and respective target portions of the sample surface relative to each other to process the target portions, and to generate a sample surface topography map representing the topography of the sample surface by analyzing the detection signals detected in response to the scanning of at least a subset of the beam lattice and the respective target portions relative to each other.

[0133]

[0147] Clause 2. The apparatus according to Clause 1, wherein the control system is configured to control the sample support, the charged particle device, and / or the detector to perform the scanning of at least a subset of the beam lattice and the respective target portions relative to each other under a plurality of focus condition settings of the apparatus.

[0134]

[0148] Clause 3. The apparatus according to Clause 2, wherein each focus condition setting defines a relative position between a focal plane and each respective target portion for each charged particle beam of at least a subset of the beam lattice.

[0135]

[0149] Clause 4. The apparatus according to Clause 2 or 3, wherein the scanning of at least a subset of the beam lattice and the respective target portions relative to each other in the plurality of focus condition settings includes each charged particle beam of at least a subset of the beam lattice processing all of the target portions corresponding to the charged particle beam once in each of the plurality of focus condition settings.

[0136]

[0150] Clause 5. The control system is configured to implement a plurality of focus condition settings by controlling the positioning of the sample support relative to the charged particle device in at least one degree of freedom, and preferably, the at least one degree of freedom includes the position of the sample support along the grating path and / or the orientation of the sample support, preferably the inclination with respect to a direction orthogonal to the grating path, of the device according to any one of Clauses 2 to 4.

[0137]

[0151] Clause 6. The control system is configured to implement a plurality of focus condition settings by controlling the positioning of the focal plane of each charged particle beam of at least a subset of the beam grating relative to the charged particle device, of the device according to any one of Clauses 2 to 5.

[0138]

[0152] Clause 7. The control system is configured such that the analysis of the detection signal includes calculating a metric representing the quality of the focus during the processing of each target portion in each focus condition setting, of the device according to any one of Clauses 2 to 6.

[0139]

[0153] Clause 8. The metric includes the contrast level of the image of the target portion derived from the detection signal, of the device according to Clause 7.

[0140]

[0154] Clause 9. The control system is configured to generate a sample surface topography map by identifying the optimal focus condition setting from a plurality of different focus condition settings for each target portion of the sample surface processed by scanning each target portion of the at least a subset of the beam grating and the sample surface relative to each other, of the device according to any one of Clauses 2 to 8.

[0141]

[0155] Clause 10. The control system is configured to import an externally derived topography map representing the topography of the sample surface measured using an external device, and to use the externally derived topography map to select one or more of different focus condition settings, of the device according to any one of Clauses 2 to 9.

[0142]

[0156] Clause 11. An apparatus according to any one of Clauses 2 to 10, including an optical measurement system configured to measure a topography map representing the topography of the sample surface, and the control system is configured to select one or more of different focus condition settings using the measured topography map.

[0143]

[0157] Clause 12. An apparatus according to any one of Clauses 2 to 11, wherein the control system is further configured to receive a sample support topography map representing the topography of the sample support and to select one or more of different focus condition settings using the sample support topography map.

[0144]

[0158] Clause 13. An apparatus according to any one of the preceding clauses, wherein the control system is configured to perform scanning using a plurality of beams focused on different focal planes.

[0145]

[0159] Clause 14. An apparatus according to Clause 13, wherein the control system is configured to perform scanning such that each of one or more of the target portions is processed at different respective times by two or more of a plurality of beams focused on different focal planes.

[0146]

[0160] Clause 15. An apparatus according to Clause 13 or 14, wherein the beam grid includes rows of beams and columns of beams, preferably lines of beams.

[0147]

[0161] Clause 16. An apparatus according to Clause 15, wherein the control system is configured to perform scanning using two or more, preferably all, of the beams in each row focused on different focal planes and / or two or more, preferably all, of the beams in each column focused on different focal planes and / or two or more, preferably all, of the beams in each line focused on different focal planes.

[0148]

[0162] Clause 17. The control system has a part parallel to a row, which enables each of one or more of the target parts to be processed by each of the beams in one of the rows, and / or a part parallel to a column, which enables each of one or more of the target parts to be processed by each of the beams in one of the columns, and / or Optionally, a part parallel to a line, which enables each of one or more of the target parts to be processed by each of the beams in one of the lines The device according to clause 15 or 16, configured to perform scanning by providing relative movement between the grating path of the grating beam along a path having the above and the sample surface.

[0149]

[0163] Clause 18. The rows and columns are orthogonal, or the angles between the rows and columns and between the rows and the lines are substantially the same, for example 60 degrees. The device according to any one of clauses 15 to 17.

[0150]

[0164] Clause 19. The control system is configured to generate a sample surface topography map by identifying the focal plane that provides the best focus on the target part for each target part of the sample surface processed by two or more beams focused on different focal planes. The device according to any one of clauses 14 to 18.

[0151]

[0165] Clause ********** The beam grating has two axes, for example a rectangular grating, or three axes, for example a hexagonal grating. The device according to any one of the preceding clauses.

[0152]

[0166] Clause 21. The control system is configured to use the generated sample surface topography map during subsequent processing of the sample using at least a part of the beam grating to control the positioning of the sample during subsequent processing and / or, for each of one or more of the charged particle beams of at least a part of the beam grating during subsequent processing, control the positioning of the focal plane. The device according to any one of the preceding clauses. It should be noted that there is an unclear part in the original text at "Clause **********" which needs to be further clarified in the source text for a more accurate translation.

[0153]

[0167] Clause 22. The charged particle device includes a plurality of proximity sensors configured to face the sample, each proximity sensor being configured to measure the distance between the proximity sensor and the sample, and preferably, the proximity sensor is a capacitive sensor, preferably a differential capacitive sensor, for the device according to any one of the preceding clauses.

[0154]

[0168] Clause 23. The control system uses the generated sample surface topography map and the output data from one or more proximity sensors during subsequent processing of the sample using at least a part of the beam lattice, and preferably controls the positioning of the sample during subsequent processing and / or controls the positioning of the focal plane for each of one or more of the charged particle beams of at least a part of the beam lattice during subsequent processing, for the device according to clause 22.

[0155]

[0169] Clause 24. The control system uses the generated sample surface topography map to select the lattice path position, preferably the optimal lattice path position, of the sample along the lattice path, and positions the sample at the lattice path position to perform subsequent processing of the sample by the beam lattice, for the device according to any one of the preceding clauses.

[0156]

[0170] Clause 25. The control system uses the generated sample surface topography map to select the common focal plane, preferably the optimal common focal plane, of the beam lattice, and performs subsequent processing of the sample by the beam lattice with at least a part of the beam lattice focused on the common focal plane, for the device according to any one of the preceding clauses.

[0157]

[0171] Clause 26. The control system is configured to select a subset of the beam lattice as a distribution of groups, which is a continuous portion of the beam lattice and / or a group of one or more charged particle beams, each group being separated from other groups by one or more charged particle beams outside the subset, with reference to a predetermined topography map of the sample surface, for the apparatus according to any one of the preceding clauses.

[0158]

[0172] Clause 27. The control system is configured to import an externally derived topography map representing the topography of the sample surface measured using an external device and to use the externally derived topography map to select a subset of the beam lattice, for the apparatus according to any one of the preceding clauses.

[0159]

[0173] Clause 28. The apparatus includes an optical measurement system configured to measure a topography map representing the topography of the sample surface, and the control system is configured to use the measured topography map to select a subset of the beam lattice, for the apparatus according to any one of the preceding clauses.

[0160]

[0174] Clause 29. The control system is configured to receive or generate a sample support topography map representing the topography of the sample support and to use the received or generated sample support topography map to calibrate the generated sample surface topography map, for the apparatus according to any one of the preceding clauses.

[0161]

[0175] Clause 30. The control system is configured to generate a sample support topology map in the absence of a sample on the sample support, desirably before the sample support supports the sample, for the apparatus according to Clause 29.

[0162]

[0176] Clause 31. The control system is the apparatus according to clause 29 or 30, configured to use the sample support topology map as a calibration for generating the sample surface topology map.

[0163]

[0177] Clause 32. The position in the sample support topology map is fed forward to determine the same position within the sample surface topology map. Desirably, the control system is configured to control the sample support based on the position within the sample support topology map to process each target position at the same position within the sample surface topology map, for the apparatus according to clause 31.

[0164]

[0178] Clause 33. The apparatus according to any one of the preceding clauses, including an objective lens array desirably proximate to the sample, and a detector desirably proximate to the sample and desirably included within the objective lens array. [[ID=ll]]

[0165]

[0179] Clause 34. An evaluation apparatus for evaluating a sample using a plurality of charged particle beams, including a sample support configured to support a sample having a sample surface, a charged particle device configured to project a beam lattice of the plurality of charged particle beams towards the sample along a lattice path of the beam lattice, a plurality of proximity sensors configured to face the sample, each proximity sensor being configured to measure the distance between the proximity sensor and the sample and provide output data, and a control system configured to import an externally derived topography map representing the topography of the sample surface measured using an external device, and to use the externally derived topography map and the output data from the plurality of proximity sensors to control the positioning of the sample while processing the sample using the beam lattice.

[0166]

[0180] Clause 35. The apparatus according to clause 34, wherein the control system is configured to control the positioning of the sample during processing of the sample by receiving a sample support topography map representing the topography of the surface of the sample support and additionally using the sample support topography map to calibrate, preferably an externally derived topography map, with the sample support topography map to generate a calibrated topography map and using the calibrated topography map to control the positioning of the sample.

[0167]

[0181] Clause 36. An evaluation apparatus for evaluating a sample using a plurality of charged particle beams, comprising: a sample support configured to support a sample having a sample surface; a charged particle device configured to project a beam lattice of the plurality of charged particle beams towards the sample along a lattice path of the beam lattice; a plurality of proximity sensors configured to face the sample, each proximity sensor being configured to measure the distance between the proximity sensor and the sample and to provide output data; and a control system configured to receive a sample support topography map representing the topography of the surface of the sample support and to use the sample support topography map and the output data from the plurality of proximity sensors to process the sample using the beam lattice while controlling the positioning of the sample.

[0168]

[0182] Clause 37. An evaluation apparatus for evaluating a sample using a plurality of charged particle beams, comprising: a sample support configured to support a sample having a sample surface; a charged particle device configured to project a beam lattice of the plurality of charged particle beams toward the sample along a lattice path of the beam lattice; an optical measurement system configured to measure a topography map representing the topography of the sample surface; and a control system configured to control the positioning of the sample during the processing of the sample by the beam lattice using the measured topography map. Desirably, the optical measurement system desirably includes an array of light sources and sensing elements arranged in a linear array, desirably dimensioned to extend in a sensing direction over the entire maximum dimension of the sample. Desirably, the array of light sources and sensing elements is configured relative to the sample support such that when the sample moves in a scanning direction relative to the linear array such that the sample is desirably angled relative to the sensing direction, desirably the optical measurement system processes the sample surface, desirably the entire sample surface. The apparatus desirably further includes a detector configured to detect signal charged particles from the sample and provide an output.

[0169]

[0183] Clause 38. An evaluation apparatus for evaluating a sample using a plurality of charged particle beams, comprising: a sample support configured to support a sample having a sample surface; a charged particle device configured to project a beam lattice of the plurality of charged particle beams toward the sample along a lattice path of the beam lattice; a plurality of proximity sensors configured to face the sample, each proximity sensor being configured to measure a distance between the proximity sensor and the sample and to provide output data; and a control system configured to generate a sample surface topography map representing the topography of the sample surface by controlling the sample support to measure respective changes in the distance between the proximity sensors and the sample surface using the proximity sensors while moving the sample relative to the charged particle device over a range of positions and / or orientations, and to control the position and / or orientation of the sample, which is controlled to move over successive ranges of different positions and / or orientations during processing, during processing of the sample by the beam lattice using the generated sample surface topography map.

[0170]

[0184] Article 39. An evaluation apparatus for evaluating a sample using a plurality of charged particle beams, comprising: a sample support configured to support a sample having a sample surface; a charged particle device configured to project a beam lattice of the plurality of charged particle beams toward the sample along a lattice path of the beam lattice; a plurality of proximity sensors configured to face the sample and preferably positioned at a distance from the lattice path, each proximity sensor being configured to measure the distance between the proximity sensor and the sample; and a control system configured to generate a sample surface topography map representing the topography of the sample surface by controlling the sample support to measure respective changes in the distance between the proximity sensors and the sample surface using the proximity sensors while moving the sample relative to the charged particle device over a range of sample positions, to control the positioning of the sample during processing of the sample by the beam lattice using the generated sample surface topography map, to receive a sample support topography map representing the topography of the sample support, and to determine a calibrated sample surface topography map using the received sample support topography map, wherein preferably, using the generated sample surface topography map to control the positioning of the sample comprises performing any one of determining using, or preferably calibrating the generation of, the sample surface topography map such that the generated sample surface topography map is calibrated by the sample support topography map.

[0171]

[0185] Clause 40. The control system is configured such that, in the calibration of the generation of the sample surface topography map, the position in the sample support topography map is feed-forwarded to determine the same position in the sample surface topography map. Desirably, the control system is configured to control the sample support based on the position in the sample support topography map to process each target position at the same position within the sample surface topography map, the apparatus according to clause 39.

[0172]

[0186] Clause 41. A method for evaluating a sample using a plurality of charged particle beams, comprising scanning at least a subset of the beam lattice of the plurality of charged particle beams and respective target portions of the sample surface to process the target portions with the beams, detecting signal charged particles from the sample, and generating a detection signal upon detection of the signal charged particles, and generating a sample surface topography map representing the topography of the sample surface by analyzing the detection signals detected in response to the scanning of at least the subset of the beam lattice and the respective target portions relative to each other.

[0173]

[0187] Clause 42. The method according to clause 41, controlling the scanning of at least a subset of the beam lattice and respective target portions relative to each other in a plurality of focus condition settings.

[0174]

[0188] Clause 43. Each focus condition setting defines the relative position between the focal plane and the respective target portion for each charged particle beam of at least the subset of the beam lattice, the method according to clause 42.

[0175]

[0189] Clause 44. The scanning of at least a subset of the beam lattice and respective target portions relative to each other in a plurality of focus condition settings includes processing all of the target portions corresponding to the charged particle beams once for each of the plurality of focus condition settings by each charged particle beam of at least the subset of the beam lattice, the method according to clause 42 or 43.

[0176]

[0190] Clause 45. Controlling the positioning of a sample support relative to a charged particle device in at least one degree of freedom to implement a plurality of focus condition settings, and preferably, the at least one degree of freedom includes the position of the sample support along a grid path and / or the orientation of the sample support, preferably the inclination with respect to a direction orthogonal to the grid path, the method according to any one of Clauses 42 to 44.

[0177]

[0191] Clause 46. Controlling the positioning of the focal plane of each charged particle beam of at least a subset of a beam grid relative to a charged particle device to implement a plurality of focus condition settings, the method according to any one of Clauses 42 to 45.

[0178]

[0192] Clause 47. Analyzing a detection signal includes calculating a metric representing the quality of focus during the processing of each target portion in each focus condition setting, the method according to any one of Clauses 42 to 46.

[0179]

[0193] Clause 48. The metric includes the contrast level of an image of a target portion derived from a detection signal, the method according to Clause 47.

[0180]

[0194] Clause 49. Further including generating a sample surface topography map by identifying an optimal focus condition setting from a plurality of different focus condition settings for each target portion of a sample surface processed by scanning a beam grid at least a subset and each target portion of the sample surface relative to each other, the method according to any one of Clauses 42 to 48.

[0181]

[0195] Clause 50. Further including importing an externally derived topography map representing the topography of a sample surface measured using an external device, and preferably, selecting one or more of different focus condition settings by using the externally derived topography map, the method according to any one of Clauses 42 to 49.

[0182]

[0196] Clause 51. The scanning is performed by a plurality of beams focused on different focal planes, and is the method according to any one of Clauses 41 to 50.

[0183]

[0197] Clause 52. Each of one or more of the target portions is processed at different respective times by two or more of a plurality of beams focused on different focal planes, and is the method according to Clause 51.

[0184]

[0198] Clause 53. The beam lattice includes rows and columns of beams, preferably lines of beams, and is the method according to Clause 51 or 52.

[0185]

[0199] Clause 54. The scanning is performed using two or more beams in each row focused on different focal planes, optionally all and / or two or more beams in each column focused on different focal planes, preferably all and / or preferably two or more beams in each line focused on different focal planes, preferably all, and is the method according to Clause 53.

[0186]

[0200] Clause 55. The scanning is a portion parallel to the row, where each of one or more of the target portions is processed by each of the beams in one of the rows, and / or a portion parallel to the column, where each of one or more of the target portions is processed by each of the beams in one of the columns, and / or optionally a portion parallel to the line, where each of one or more of the target portions is enabled to be processed by each of the beams in one of the lines, and includes providing relative movement between the lattice path of the lattice beam and the sample surface along a path having such portions, and is the method according to Clause 53 or 54.

[0187]

[0201] Clause 56. The rows and columns are orthogonal, or the angles between the rows and columns and between the rows and lines are substantially the same, for example 60 degrees, and is the method according to any one of Clauses 53 to 55.

[0188]

[0202] Clause 57. The method according to any one of Clauses 52 to 56, wherein generating a sample surface topography map includes identifying a focal plane that provides the best focus on the target portion for each target portion of the sample surface processed by two or more beams focused on different focal planes.

[0189]

[0203] Clause 58. The method according to any one of Clauses 41 to 57, wherein the beam lattice has two axes, for example a rectangular lattice, or three axes, for example a hexagonal lattice.

[0190]

[0204] A method for evaluating a sample using a plurality of charged particle beams, the method including importing an externally derived topography map representing the topography of the sample surface of the sample measured using an external device, and using the externally derived topography map and output data from a plurality of proximity sensors that measure the distance from the proximity sensors to the sample to process the sample using a beam lattice of the plurality of charged particle beams while controlling the positioning of the sample.

[0191]

[0205] A method for evaluating a sample using a plurality of charged particle beams, the method including receiving a sample support topography map representing the topography of the surface of a sample support that supports the sample, and using the sample support topography map and output data from a plurality of proximity sensors that measure the distance from the proximity sensors to the sample to process the sample using a beam lattice of the plurality of charged particle beams while controlling the positioning of the sample.

[0192]

[0206] A method for evaluating a sample using a plurality of charged particle beams, the method including optically measuring a topography map representing the topography of the sample surface of the sample, and using the measured topography map to control the positioning of the sample during processing of the sample by a beam lattice of the plurality of charged particle beams.

[0193]

[0207] Clause 62. A method for evaluating a sample using a plurality of charged particle beams, the method comprising: generating a sample surface topography map representing the topography of the sample surface of the sample by measuring respective changes in the distance between a proximity sensor and the sample surface using the proximity sensor while moving the sample over a range of positions and / or orientations; and controlling the position and / or orientation of the sample, which is controlled to move over successive ranges of different positions and / or orientations during processing of the sample by a beam lattice of the plurality of charged particle beams, using the generated sample surface topography map.

[0194]

[0208] Clause 63. A method for evaluating a sample using a plurality of charged particle beams, the method comprising: generating a sample surface topography map representing the topography of the sample surface of the sample by measuring respective changes in the distance between a proximity sensor and the sample surface using the proximity sensor while moving the sample over a range of sample positions; controlling the positioning of the sample during processing of the sample by a beam lattice of the plurality of charged particle beams using the generated sample surface topography map; receiving a sample support topography map representing the topography of a sample support supporting the sample; and performing either a) determining a calibrated sample surface topography map, preferably by using the generated sample surface topography map for controlling the positioning of the sample, using the calibrated sample surface topography map, or b) calibrating the generation of the sample surface topography map such that preferably the generated sample surface topography map is calibrated by the sample support topography map.

Claims

1. An evaluation apparatus for evaluating a sample using a plurality of charged particle beams, comprising: a sample support for supporting a sample having a sample surface; a charged particle device for projecting a beam lattice of a plurality of charged particle beams toward the sample along a lattice path of the beam lattice; a detector for detecting signal charged particles from the sample and generating a detection signal when the signal charged particles are detected; a control system for controlling the sample support, the charged particle device, and / or the detector to scan at least a subset of the beam lattice and respective target portions of the sample surface relative to each other to process the target portions; and generate a sample surface topography map representing the topography of the sample surface by analyzing detection signals detected in response to the scanning of at least the subset of the beam lattice and the respective target portions relative to each other. The evaluation apparatus further includes a control system configured to perform the above operations. The evaluation apparatus including the above components.

2. The apparatus according to claim 1, wherein the control system controls the sample support, the charged particle device, and / or the detector to perform the scanning of at least the subset of the beam lattice and the respective target portions relative to each other under a plurality of focus condition settings of the apparatus.

3. The apparatus according to claim 2, wherein each focus condition setting defines a relative position between a focal plane and the respective target portion for each charged particle beam of at least the subset of the beam lattice.

4. The apparatus according to claim 2 or 3, wherein the scanning of at least the subset of the beam lattice and the respective target portions relative to each other in the plurality of focus condition settings includes each charged particle beam of at least the subset of the beam lattice processing all of the target portions corresponding to the charged particle beam once in each of the plurality of focus condition settings.

5. The control system implements the plurality of focus condition settings by controlling the positioning of the sample support relative to the charged particle device in at least one degree of freedom, and preferably, the at least one degree of freedom includes the position of the sample support along the grid path and / or the orientation of the sample support, preferably the inclination with respect to a direction orthogonal to the grid path, the apparatus according to any one of claims 2 to 4.

6. The control system implements the plurality of focus condition settings by controlling the positioning of the focal plane of each charged particle beam of the at least subset of the beam grid relative to the charged particle device, the apparatus according to any one of claims 2 to 5.

7. The control system is configured such that the analysis of the detection signal includes calculating a metric representing the quality of focus during the processing of each target portion at each focus condition setting, the apparatus according to any one of claims 2 to 6.

8. The control system generates the sample surface topography map by identifying an optimal focus condition setting from the plurality of different focus condition settings for each target portion of the sample surface processed by the scanning of the at least subset of the beam grid and the respective target portions of the sample surface relative to each other, the apparatus according to any one of claims 2 to 7.

9. The control system imports an externally derived topography map representing the topography of the sample surface measured using an external device, and uses the externally derived topography map to select one or more of the different focus condition settings, the apparatus according to any one of claims 2 to 8.

10. including an optical measurement system that measures a topography map representing the topography of the sample surface, and the control system uses the measured topography map to select one or more of the different focus condition settings, the apparatus according to any one of claims 2 to 9.

11. The control system further receives a sample support topography map representing the topography of the sample support, and uses the sample support topography map to select one or more of the different focus condition settings, the apparatus according to any one of claims 2 to 10.

12. During subsequent processing of the sample using at least a portion of the beam lattice, the control system uses the generated sample surface topography map to control the positioning of the sample during the subsequent processing, and / or during the subsequent processing, for each of one or more of the charged particle beams of the at least a portion of the beam lattice, control the positioning of the focal plane The apparatus according to any one of claims 1 to 11, which performs the above.

13. The charged particle device includes a plurality of proximity sensors facing the sample, each proximity sensor measures the distance between the proximity sensor and the sample, and preferably, the proximity sensor is a capacitive sensor, preferably a differential capacitive sensor. The apparatus according to any one of claims 1 to 12.

14. The control system uses the generated sample surface topography map and the output data from the one or more proximity sensors during subsequent processing of the sample using at least a portion of the beam lattice. The apparatus according to claim 13.

15. The control system selects the lattice path position of the sample along the lattice path using the generated sample surface topography map, and / or the control system selects a common focal plane using the generated sample surface topography map. The apparatus according to any one of claims 1 to 14.

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