Electro-optical device and method for obtaining topographic information about surface of sample

Abstract

Apparatus and methods for obtaining topographic information about a surface of a sample are disclosed. In one arrangement, the sensing system includes a set of proximal sensors for measuring positions of respective portions of the sample surface, and a distal sensor positioned further away from a sub-beam path of the plurality of beams than the proximal sensors. The distal sensor measures a position of a portion of the sample surface relative to the distal sensor. A control system controls the charged particle device to treat a sample surface in a multi-beam processable region using multiple beams. One stage causes a multi-beam processable region to move along a processing path in a reference frame of a sample. The sensing system uses at least a distal sensor to obtain topography information about the surface of the sample in a selected portion of the processing path before the multi-beam processable region reaches the selected portion of the processing path.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to EP application 22186294.9 filed on July 21, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to apparatus and methods for obtaining topographic information about a sample surface, particularly in the context of evaluating the sample using multiple beams of charged particles. Background Art

[0004] When manufacturing semiconductor integrated circuit (IC) chips, due to optical effects and incidental particles, etc., undesirable pattern defects will inevitably appear on the substrate (i.e., wafer) or mask during the manufacturing process, thereby reducing the yield. Therefore, monitoring the degree of undesirable pattern defects is an important process in IC chip manufacturing. More generally, evaluating (e.g., inspecting and / or measuring) the surface of a substrate or other object / material is an important process during and / or after its manufacturing process.

[0005] Known evaluation tools (referred to herein as evaluation systems) use charged particle beams to evaluate objects (which may be referred to as samples), such as detecting pattern defects. These systems typically use electron microscopy techniques, such as scanning electron microscopes (SEMs). In an SEM, a primary electron beam is subjected to a final deceleration step at a relatively high energy so that it lands on a sample with a relatively low landing energy. The electron beam is focused as a probe spot on the sample. The interaction between the material structure at the detection point and the landing electrons in the electron beam causes signal electrons to come out of the surface, for example as signal electrons, such as secondary electrons, backscattered electrons, or Auger electrons, which may be more generally referred to as signal particles. Signal electrons may be emitted from the material structure of the sample. By scanning the primary electron beam as a detection point on the sample surface, signal electrons may be emitted on the sample surface. By collecting these emitted signal electrons from the sample surface, the pattern inspection system may obtain an image representing the characteristics of the material structure of the sample surface.

[0006] The throughput of an evaluation system can be increased by increasing the number of beams that are simultaneously incident on the sample. An evaluation system configured to operate in this manner may be referred to as a multi-beam system, and may project a very large number of individual beams simultaneously onto the sample in parallel over a relatively large area on the sample surface, which area may be referred to as the field of view (FoV). Having a large FoV enables high throughput. However, it has proven challenging to accurately focus the beams over such a large FoV due to the non-uniform topology of the sample surface. These problems can be corrected by obtaining a topographic map of the sample surface, but the measurements used to obtain such a map are time consuming and may be inaccurate, for example due to changes in the surface topography over time and / or due to inaccurate stage positioning. Summary of the invention

[0007] It is an object of the present disclosure to provide apparatus and methods that support improved focus control in an arrangement for evaluating a sample using multiple beams of charged particles.

[0008] According to one aspect of the present invention, there is provided an electron optical apparatus, comprising: a stage configured to support a sample having a sample surface; a charged particle device configured to project a plurality of beams toward the sample along a multi-beam path intersecting the sample in a multi-beam processable region, the plurality of beams comprising a plurality of charged particle sub-beams, the plurality of charged particle sub-beams having paths within the multi-beam path that are desirably arranged in a grid; a sensing system comprising: a set of proximal sensors positioned proximal to the paths of the plurality of sub-beams, each proximal sensor configured to measure a position of a corresponding portion of the sample surface relative to the proximal sensor, and one or more distal sensors, the distal sensor or each distal sensor The sensor is positioned farther away from the path of the sub-beam than the proximal sensor, the distal sensor or each distal sensor is configured to measure the position of the corresponding portion of the sample surface relative to the distal sensor; and a control system configured to: control the charged particle device to process the sample surface in a multi-beam processable area using multiple beams, and desirably evaluate the sample surface using multiple beams; control the control system to move the multi-beam processable area along the processing path in a reference frame of the sample; and control the sensing system to obtain morphological information about the sample surface in a selected portion of the processing path before the multi-beam processable area reaches the selected portion of the processing path using at least one or more distal sensors.

[0009] According to one aspect of the present invention, an electron optical device is provided, comprising: a stage configured to support a sample having a sample surface; a charged particle device configured to project multiple beams toward the sample along a multi-beam path, the multi-beam path intersecting with the sample in a region processable by multiple beams to process the sample using multiple beams, the multiple beams comprising multiple charged particle sub-beams, the multiple charged particle sub-beams having paths within the multi-beam path that are desirably arranged in a grid; and a sensing system comprising multiple sensors, each sensor being configured to measure a position of a corresponding portion of the sample surface outside the region processable by multiple beams relative to the sensor, wherein the multiple sensors comprise at least a first sensor, a second sensor, and a third sensor, the first sensor, the second sensor, and the third sensor being positioned so that in a projection of the positions of the sensors and the region processable by multiple beams on a plane parallel to the sample, a vector connecting the positions of the first sensor and the second sensor is substantially equal to or opposite to a vector joining the position of the third sensor to the center of the region processable by multiple beams.

[0010] According to one aspect of the present invention, a method for obtaining morphological information about a sample surface is provided, comprising: projecting multiple beams of charged particles toward the sample along a multi-beam path, the multi-beam path intersecting with the sample in a region processable by multiple beams to process the sample surface in the region processable by multiple beams, the multiple beams comprising multiple sub-beams, the multiple sub-beams having paths within the multi-beam path that are expected to be arranged in a grid; using a set of proximal sensors positioned close to the paths of the multiple sub-beams to measure positions of corresponding portions of the sample surface relative to the proximal sensors; using one or more distal sensors positioned farther from the paths of the sub-beams than the proximal sensors to measure one or more corresponding portions of the sample surface relative to the one or more distal sensors; providing relative movement between the region processable by multiple beams and the sample so that the region processable by multiple beams moves along the processing path in a reference frame of the sample; and using at least one or more distal sensors to obtain morphological information about the sample surface in a selected portion of the processing path before the region processable by multiple beams reaches the selected portion of the processing path.

[0011] According to one aspect of the present invention, a method for obtaining morphological information about a sample surface is provided, comprising: projecting multiple beams of charged particles toward the sample along a multi-beam path, the multi-beam path intersecting with the sample in a region that can be processed by multiple beams to process the sample using multiple beams, the multiple beams comprising multiple sub-beams, the multiple sub-beams having paths that are expected to be arranged in a grid within the multi-beam path; obtaining morphological information about the sample surface using multiple sensors to measure positions of corresponding portions of the sample surface outside the region that can be processed by multiple beams relative to the sensors, wherein the multiple sensors comprise at least a first sensor, a second sensor, and a third sensor, the first sensor, the second sensor, and the third sensor being positioned so that in a projection of the positions of the sensors and the region that can be processed by multiple beams on a plane parallel to the sample, the position of a vector connecting the positions of the first sensor and the second sensor is substantially equal to or opposite to a vector connecting the position of the third sensor to the center of the region that can be processed by multiple beams.

[0012] According to one aspect of the invention, there is provided a computer program comprising instructions interpretable by a computer controlling an evaluation device, the computer program comprising instructions for executing a method according to any other aspect of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above and other aspects of the present disclosure will become more apparent through the description of exemplary embodiments with reference to the attached drawings.

[0014] Figure 1 is a schematic diagram illustrating an exemplary charged particle beam inspection apparatus.

[0015] Figure 2 is shown as Figure 1 Schematic diagram of an exemplary multi-beam apparatus of a portion of an exemplary charged particle beam inspection apparatus.

[0016] Figure 3 is a schematic diagram of an exemplary electron optical train including a focusing lens array, an objective lens array, and a charged particle detector array.

[0017] Figure 4 is a schematic cross-sectional view of a portion of an exemplary arrangement of an objective lens array with an exemplary arrangement of a detector array.

[0018] Figure 5 yes Figure 4 Bottom view of a portion of the objective lens array.

[0019] Figure 6 yes Figure 4 Bottom view of a modified version of a portion of the objective lens array.

[0020] Figure 7 is a schematic diagram of an exemplary electron optics device including a beam splitter.

[0021] Figure 8 is a schematic bottom view of the beam grid and sensor.

[0022] Fig. 9 yes Figure 8 Schematic side view of a portion of a sample downstream of an arrangement of the type shown.

[0023] Fig.10 A projection onto a plane is shown of a multi-beam processable area and the location of sensors, including a set of proximal sensors and distal sensors, which can be configured to function as forward-pointing sensors.

[0024] Fig.11 A projection on a plane showing the area of ​​multi-beam processing and the location of sensors, the sensors including a set of proximal sensors, distal sensors that can be configured to operate as forward sensors, and distal sensors that can be configured to operate as side sensors.

[0025] Fig.12 A projection onto a plane of a multi-beam processable area and the positions of sensors is shown, the sensors including a set of proximal sensors, a distal sensor that can be configured to operate as a forward sensor, a distal sensor that can be configured to operate as a rearward sensor, and two distal sensors that can be configured to operate as side sensors.

[0026] Fig.13 Schematically depicts Fig.11 An arrangement of the type depicted in , which begins processing a sample along a processing path that includes parallel routes and offset routes.

[0027] Fig.14 Schematically depicts Fig.13 Samples shown are at a later stage of processing.

[0028] Fig.15 Schematically depicted is how topographic information about a region of a sample surface is acquired incrementally and in real time (or "real time") as a multi-beam processable region moves relative to the sample surface.

[0029] Fig.16 Depicts relative to Fig.15 The topography information is progressively acquired at later points along the processing path.

[0030] Fig.17 Describes the Fig.15 and Fig.16 The topography information is progressively acquired at later points along the processing path.

[0031] Fig.18is a schematic side cross-sectional view of a multi-beam grid path and sample, showing in exaggerated form how certain types of spatial deformations of sensor embodiments can cause focusing errors.

[0032] Fig.19 The projections on the plane of the multi-beam processable area and the positions of the sensors are shown to illustrate the vector relationship between the positions of the first sensor, the second sensor, the third sensor and the center of the multi-beam processable area.

[0033] Fig. 20 Shows Fig.19 Projections of with other vector relationships.

[0034] Fig.21 is a flow chart describing a method for generating and using correction values ​​to determine topographic information and process a sample. DETAILED DESCRIPTION

[0035] Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings, wherein, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations set forth in the following description of the exemplary embodiments do not represent all implementations consistent with the present invention. Instead, they are merely examples of devices and methods consistent with various aspects of the present invention as described in the appended claims.

[0036] The increase in computing power of electronic devices can be achieved by significantly increasing the packaging density of circuit components (such as transistors, capacitors, diodes, etc.) on IC chips, which reduces the physical size of the device. This is achieved by increasing the resolution, which enables the manufacture of smaller structures. For example, the IC chip of a smartphone (which is the size of a thumb and available in 2019 or earlier) may include more than 2 billion transistors, each of which is less than 1 / 1000 the size of a human hair. It is not surprising that semiconductor IC manufacturing is a complex and time-consuming process with hundreds of individual steps. Even an error in one step has the potential to greatly affect the operation of the final product. In some cases, even a single defect may cause device failure. The goal of the manufacturing process is to increase the overall yield of the process. For example, in order to obtain a 75% yield for a 50-step process (where one step can indicate the number of layers formed on the wafer), the yield of each individual step must be greater than 99.4%. If the yield of each individual step is 95%, the total process yield will be as low as 7%.

[0037] While high process yields are desired in IC chip manufacturing facilities, it is also essential to maintain high substrate (i.e., wafer) throughput, defined as the number of substrates processed per hour. The presence of defects may compromise both high process yields and high substrate throughput. This is particularly true if operator intervention is required to review the defects. Therefore, detecting and identifying micron and nanometer-scale defects at high throughput by inspection systems, such as scanning electron microscopes ('SEMs'), is important to maintaining high throughput and low costs.

[0038] The SEM includes a scanning device and a detector device. The scanning device includes an irradiation device, which includes an electron source for generating primary electrons and a projection device for scanning a sample such as a substrate using one or more focused primary electron beams. At least the irradiation device or irradiation system and the projection device or projection system together can be collectively referred to as an electron optical device or column. The primary electrons interact with the sample and generate secondary electrons. The detection device captures the secondary electrons from the sample as the sample is scanned so that the SEM can create an image of the scanned area of ​​the sample. For high-throughput inspection, some inspection devices use multiple focused primary electron beams, i.e., multi-beams. The component beams in the multi-beams can be referred to as sub-beams or beam waves. The multi-beams can scan different parts of the sample at the same time. Therefore, a multi-beam inspection device can inspect the sample at a much higher speed than a single-beam inspection device.

[0039] The following describes a known implementation of a multi-beam inspection device.

[0040] The drawings are schematic. Therefore, for the sake of clarity, the relative sizes of the components in the drawings are exaggerated. 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 various embodiments are described. Although the description and drawings refer to electron-optical devices, it is to be understood that the embodiments are not used to limit the present disclosure to specific charged particles. Therefore, references to electrons throughout this article can be considered more generally as references to charged particles, which are not necessarily electrons.

[0041] Now refer to Figure 1 , Figure 1 is a schematic diagram illustrating 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. Figure 1 The charged particle beam inspection apparatus 100 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 between different components of the evaluation system, including, for example, in the electron beam device 40. The electron beam device 40 is located in the main chamber 10.

[0042] The EFEM 30 includes a first loading port 30a and a second loading port 30b. The EFEM 30 may include additional loading ports. The first loading port 30a and the second loading port 30b may, for example, accommodate a substrate front opening pod (FOUP) containing a substrate to be inspected (e.g., a semiconductor substrate or a substrate made of (multiple) other materials) or a sample (substrate, wafer, and sample are collectively referred to as "sample" hereinafter). One or more robotic arms (not shown) in the EFEM 30 transport the sample to the load lock chamber 20.

[0043] The load lock chamber 20 is used to remove the gas around the sample. This will produce a vacuum with a local gas pressure lower than the pressure in the surrounding environment. The load lock chamber 20 can be connected to a load lock vacuum pump system (not shown), which removes gas particles in the load lock chamber 20. The operation of the load lock vacuum pump system enables the load lock chamber to reach a first pressure lower than atmospheric pressure. After reaching the first pressure, one or more robot arms (not shown) transport the sample from the load lock chamber 20 to the main chamber 10. The main chamber 10 is connected to the main chamber vacuum pump system (not shown). The main chamber vacuum pump system removes gas particles in the main chamber 10 so that the pressure around the sample reaches a second pressure lower than the first pressure. After reaching the second pressure, the sample is transported to an electron beam device, by which the sample can be inspected. The electron beam device 40 may include a multi-beam electron optical device.

[0044] The controller 50 is connected to the electron beam device 40 in a signal manner (e.g., electronically), for example, 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 processing circuit devices configured to perform various signal and image processing functions. Although the controller 50 is in Figure 1 Controller 50 is shown as being outside of a structure including main chamber 10, load lock chamber 20, and EFEM 30, but it is to be understood that controller 50 may be part of the structure. Controller 50 may be located in one of the constituent elements of the charged particle beam inspection device, or it may be distributed over at least two constituent elements. Although the present disclosure provides an example of a main chamber 10 housing an electron beam inspection device, it should be noted that the broadest aspects of the present disclosure are not limited to chambers housing electron beam inspection devices. On the contrary, it is to be understood that the foregoing principles may also be applied to arrangements of other systems and other devices operating at a second pressure.

[0045] Reference now Figure 2 , Figure 2 4 is a schematic diagram showing an exemplary charged particle beam device 40. The electron beam device 40 may be used as Figure 11. The electron beam device 40 includes an electron source 201 and an evaluation device. The evaluation device includes a charged particle device 230. The charged particle device 230 may include or consist of a projection device for directing a primary charged particle beam 202 toward a sample 208. The electron source 201 and the charged particle device 230 may be collectively referred to as an irradiation device for generating a primary charged particle beam 202. The evaluation device includes a sample support supporting the sample 208. The sample support in this example includes a sample holder 207. The sample holder 207 holds a sample 208 (e.g., a substrate or a mask) for evaluation. The sample holder 207 is supported by a motorized or actuated stage 209. The electron beam device 40 also includes a detector 240. The detector 240 detects signal charged particles (e.g., electrons) from the sample 208. The detector 240 generates a detection signal when the signal charged particles are detected.

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

[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. Although three beams are shown for simplicity, there may be tens, hundreds, thousands, tens of thousands or even hundreds of thousands (or more) of beams. A beam may be referred to as a beam wave or a beamlet. A plurality of charged particle beams may be collectively referred to as a multi-beam or a beam grid. A beam grid having such a plurality of beams (e.g., more than one thousand beams) may have, for example, a field of view of more than 0.5 mm, for example, in the range of 0.5 mm to 30 mm or 1 mm to 30 mm, for example, in the range of 0.5 mm to 15 mm.

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

[0049] The charged particle device 230 can be configured to focus the beams 211, 212, and 213 onto the sample 208 for inspection, and three probe spots 221, 222, and 223 can be formed 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 across separate scanning areas in a portion of the surface of the sample 208. In response to the incidence of the primary beams 211, 212, and 213 on the probe spots 221, 222, and 223 on the sample 208, electrons are generated from the sample 208, the electrons including secondary electrons and backscattered electrons, which can be referred to as signal charged particles or signal particles. The secondary electrons typically have a charge of up to 50 electron volts ( ≤ 50 eV), while the backscattered electrons typically have an electron energy between 50 electron volts (50 eV) and the landing energy of the primary electron beams 211, 212 and 213.

[0050] The detector 240 may send detection signals generated in the detector 240 (e.g., as imaging or detection signals) to the controller 50 or a signal processing system (not shown, which may be part of the controller 50), for example, to construct an image of a corresponding scanned area of ​​the sample 208. The detector 240 may be at least partially incorporated into the charged particle device 230, or may be separated from the charged particle device 230, for example by providing a secondary optical train to guide signal charged particles (e.g., secondary electrons and / or backscattered electrons) to the detector 240.

[0051] The controller 50 may include an image processing system including an image acquisition device (not shown) and a storage device (not shown). For example, the controller may include a processor, a computer, a server, a mainframe, a terminal, a personal computer, any type of mobile computing device, etc., or a combination thereof. The image acquisition device may include at least a portion of the processing function of the controller. Therefore, the image acquisition device may include at least one or more processors. The image acquisition device may be communicatively coupled to a detector 240 that allows signal communication, such as an electrical conductor, a fiber optic cable, a portable storage medium, IR, Bluetooth, the Internet, a wireless network, radio, etc., or a combination thereof. The image acquisition device may receive a detection signal from the detector 240, may process the data included in the signal, and may construct an image therefrom. Therefore, the image acquisition device may acquire an image of the sample 208. The image acquisition device may also perform various post-processing functions, such as generating contours, superimposing indicators on the acquired image, etc. The image acquisition device may be configured to perform adjustments to the brightness and contrast of the acquired image, etc. The storage device may be a storage medium such as a hard disk, a flash drive, a cloud storage device, a random access memory (RAM), other types of computer-readable memory, etc. The memory may be coupled to the image acquirer and may be used to save the scanned raw image data as a raw image and a post-processed image.

[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 can correspond to a scanning operation for performing charged particle imaging. The acquired image can be a single image including multiple imaging regions. The single image can be stored in a storage device. The single image can be an original image that can be divided into multiple regions. Each region can include an imaging region that includes a feature of the sample 208. The acquired image can include multiple images of a single imaging region of the sample 208 sampled multiple times within a time period. Multiple images can be stored in a memory. The controller 50 can be configured to perform an image processing step with multiple images of the same position of the sample 208.

[0053] The controller 50 may include a measurement circuit device (e.g., an analog-to-digital converter) to obtain the distribution of the detected secondary electrons, or more generally, the distribution of the signal charged particles. A portion of the controller for this function may be included in or near the detector. The electron distribution data collected during the detection time window can be used in conjunction with the corresponding scan path data of each of the primary beams 211, 212, and 213 incident on the sample surface to reconstruct an image of the inspected sample structure. The reconstructed image can be used to reveal various features of the internal or external structure of the sample 208. Thus, the reconstructed image can be used to reveal any defects that may be present in and / or on the sample.

[0054] The controller 50 may control the actuated stage 209 to move the sample 208 during inspection of the sample 208, for example to provide a scanning motion of the stage relative to the path of the primary beam. The controller 50 may enable the actuated stage 209 to move the sample 208 in a direction such as a portion of the scanning motion of the stage, desirably continuously, for example at a constant speed, at least during the inspection of the sample. The controller 50 may control the movement of the actuated stage 209 such that it changes the speed of movement of the sample 208 according to various parameters. For example, the controller may control the speed of the stage (including its direction) according to the characteristics of the inspection step and / or scan of the scanning process, such as disclosed in EPA 21171877.0 filed on May 3, 2021, which is incorporated herein by reference with respect to at least the combined stepping and scanning strategy of the stage. In controlling the actuated stage, actuation of the stage and therefore actuation of the sample may enable the sample to be positioned, for example, in real time relative to the path of the primary beam.

[0055] Figure 3 Schematic diagram of an exemplary charged particle device 41 for use in an evaluation device. The charged particle device 41 may be referred to as an electron optical column or an electron optical device. For ease of explanation, the lens array is schematically described here with an elliptical array. Each ellipse represents a lens in the lens array. An ellipse is used conventionally to represent a lens, similar to the biconvex shape often used in optical lenses. In the context of a charged particle device such as that discussed here, it should be understood that the lens array will typically operate electrostatically, and therefore any physical element of a biconvex shape may not be required. As described below, the lens array may instead include a plurality of plates with holes. Each plate with a hole may be referred to as an electrode. The electrodes may be arranged in series along the path of a beam grid of a plurality of charged particle beams (which may also be referred to as sub-beams). Therefore, the electrodes are also connected in series along the path of the charged particle beam of the beam grid.

[0056] The electron source 201 guides electrons to an array of focusing lenses 231 that form part of the charged particle device 230. The electron source 201 is desirably a high brightness thermal field emitter with a good compromise between brightness and total emission current. There may be tens, hundreds, or thousands or even tens of thousands of converging lenses 231. The converging lenses of the array 231 may include a multi-electrode lens and have a construction based on EP1602121A1, which is specifically incorporated herein by reference to disclose a lens array that divides an electron beam into a plurality of sub-beams, wherein the array provides a lens for each sub-beam. The converging lens array may take the form of at least two plates, preferably three plates, the plates being used as electrodes, the holes in each plate being aligned with the holes in the other plates, for defining the path of the charged particle beam through the plate. During operation, at least two plates are maintained at different potentials to achieve the desired lens effect. Between the plates of the converging lens array is an electrically insulating plate, for example made of an insulating material such as ceramic or glass, with one or more holes for the charged particle beam. Additionally or alternatively, one or more plates may feature holes, each hole having its own electrode, for example with an array of electrodes around its perimeter or arranged as a group of holes with a common electrode. In a variation, one or more plates may include multiple sections or strips with multiple holes. In another alternative arrangement, a macro collimator is provided instead of a converging lens array. The macro collimator may act on the beam from source 201 before the beam is split into multiple beams. The macro collimator may be implemented magnetically, electrostatically, or magnetically and electrostatically.

[0057] In some embodiments, the converging lens array is formed by an array of three plates, where the charged particles have the same energy as they enter and leave each lens, an arrangement that can be referred to as a single lens. Thus, the dispersion occurs only within the single lens itself (between the entrance and exit electrodes of the lens), limiting off-axis chromatic aberration. When the thickness of the converging lens is small, such as a few millimeters, this aberration has little or negligible effect.

[0058] Each converging lens in the array directs electrons into a respective beam 211, 212, 213, which is focused at a respective intermediate focus 233. A collimator or array of collimators may be positioned to operate on the respective intermediate focus 233. The collimator may take the form of a deflector 235 disposed at the intermediate focus 233. The deflector 235 is configured to bend the respective beam 211, 212, 213 by an amount to ensure that the chief ray (which may also be referred to as the beam axis) is incident on the sample 208 substantially perpendicularly (i.e., substantially 90° to the nominal surface of the sample). Note that in an arrangement with a macroscopic converging lens, the converging lens may collimate or help collimate the source beam, or in an embodiment, collimate multiple beams.

[0059] The objective lens array 401 is arranged downstream of the deflector 235. The objective lens array 401 comprises an objective lens 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 may comprise two or more, preferably at least three, plate electrode arrays connected to respective potential sources.

[0060] Optionally, a control lens array 250 is arranged between the deflector 235 and the objective lens array 401. The control lens array 250 includes a control lens for each beam 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 corresponding potential sources. The function of the control lens array 250 is to optimize the beam opening angle relative to the reduction of the beam and / or control the beam energy delivered to the objective lens, each objective lens directing the corresponding beam 211, 212, 213 onto the sample 208. In one embodiment, the control lens array can be considered as a part of the objective lens, for example as an additional plate associated with the objective lens array.

[0061] Optionally, a scanning deflector array 260 is disposed between the control lens array 250 and the objective lens array 401. The scanning deflector array 260 includes a scanning deflector for each beam 211, 212, 213. Each scanning deflector is configured to deflect the corresponding beam 211, 212, 213 in one or two directions to scan the beam across the sample 208 in one or two directions. Alternatively, a macro scanning deflector may be provided to scan the charged particle beam over the sample 208. A macro scanning deflector may be provided upstream of the control lens array 250. In one embodiment, such a macro scanning deflector may operate on the source beam and may be present together with a macro converging lens.

[0062] The detector module 402 may include a detector. The detector module 402 may be disposed 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 is described below. Note that the detector may additionally or alternatively have detector elements upstream of the primary beam path along the objective lens array 401 or even the control lens array 250. The detector module may be an array of detector elements (e.g., a detector array). Each element may be associated with a separate beam, for example, positioned to detect signal particles generated by a separate beam.

[0063] Figure 3The charged particle device 41 can be configured to control the landing energy of electrons on the sample 208 by changing the potential applied to the electrodes of the control lens and the objective lens. The control lens and the objective lens work together 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 (or more generally signal particles) according to the properties of the sample being processed such as evaluation (e.g., inspection or measurement). The detector module can be included in the objective lens assembly.

[0064] The objective lens can be configured to reduce the electron beam by more than 10 times, desirably in the range of 50 to 100 or more. The objective lens can include three electrodes, for example the objective lens can include a middle electrode, a lower electrode and an upper electrode. The upper electrode can be omitted. An objective lens with only two electrodes has lower aberrations than an objective lens with more electrodes. A three-electrode objective lens can have a larger potential difference between the electrodes, thereby enabling a stronger lens. Additional electrodes (i.e., more than two electrodes) provide additional degrees of freedom for controlling the trajectory of the electrons, such as focusing the secondary electrons as well as the incident beam.

[0065] In some embodiments, the objective lens array assembly includes a detector having a detector module 402 downstream of at least one electrode of the objective lens array 401. The detector module 402 may include or even take the form of a detector array. In one embodiment, at least a portion of the detector is adjacent to and / or integrated with the objective lens array 401. For example, the detector module 402 may be implemented by integrating a CMOS chip detector into the bottom electrode of the objective lens array 401. Integrating the detector module 402 into the objective lens array may replace or be in addition to the secondary column. The CMOS chip is preferably oriented to face the sample (because the distance between the sample and the bottom of the electron optical device is small). The distance between the sample and the bottom of the electron optical device may be, for example, in the range of 10 microns to 400 microns, desirably in the range of 50 microns to 200 microns, optionally about 100 microns). It should be noted that even in the case where the detector is upstream of the most downstream electron optical element of the charged particle device, there may be a close, for example, similar distance interval (e.g., 100 μm) between the most downstream electron optical element and the sample. In one embodiment, an electrode for capturing signal charged particles is formed in the top metal layer of the CMOS device. The electrode can be formed in other layers of the substrate, such as other layers of the CMOS chip. The power supply signal and control signal of the CMOS can be connected to the CMOS through silicon vias. For robustness, the bottom electrode is preferably composed of two components: the CMOS chip and a passive Si plate with a hole. The plate shields the CMOS from the influence of high electric fields.

[0066] In one embodiment, a single electrode surrounds at least some of the holes. In one arrangement, for example, a single electrode is allocated around each hole. In another embodiment, multiple electrode elements are arranged around each hole. The signal charged particles captured by the electrode elements around a hole can be combined into a single detection signal or used to generate independent detection signals. The electrode elements can be separated radially (i.e., to form multiple concentric rings), angularly (i.e., to form multiple fan-shaped pieces), radially and angularly, or in any other convenient manner.

[0067] exist Figure 4 An exemplary embodiment of a detector integrated into the objective lens array 401 is shown in Figure 4 A portion of an objective lens array 401 is shown in schematic cross-sectional view. In this embodiment, the detector comprises a detector module 402 comprising a plurality (eg, an array) of detector elements 405 (in Figure 5 ) (e.g., sensor elements such as capture electrodes), preferably as an array of detector elements (i.e., a plurality of detector elements in a pattern or arrangement preferably on a two-dimensional surface). In this embodiment, the detector module 402 is arranged at the output side of the objective lens array. The output side is the output side of the objective lens array 401. Figure 5 4 is a bottom view of a detector module 402, which includes a substrate 404 on which a plurality of detector elements 405 (eg, capture electrodes) are disposed, each of which surrounds a beam aperture 406. The beam aperture 406 may be formed by etching through the substrate 404. Figure 5 In the illustrated arrangement, the beam holes 406 are shown in a rectangular array. The beam holes 406 may also be arranged differently, for example, Figure 6 The hexagonal close-packed array shown.

[0068] The above-described integrated detector module 402 is particularly advantageous when used with a tool having an adjustable landing energy, since the capture of signal particles (e.g., secondary electrons) can be optimized for a range of landing energies. The detector module comprising an array of detector elements (or a capture electrode-detector module even in array form) can also be integrated into other electrode arrays, not just the lowest electrode array. Further details and alternative arrangements of detector modules integrated into an objective lens can be found in EP application number 20184160.8, which is incorporated herein by reference.

[0069] A power source may be provided to apply corresponding potentials to electrodes of the objective lenses of the objective lens array 401 and the control lenses of the control lens array 250 .

[0070] In one embodiment, a charged particle device array (or device array) is provided. The array may include a plurality of any charged particle devices (e.g., electron optical columns) herein. Each charged particle device in the array focuses a corresponding plurality of charged particle beams onto different regions of the same sample 208. Each charged particle device in the array may derive a corresponding plurality of charged particle beams from different corresponding sources 201. Each corresponding source 201 may be a source in a plurality of sources 201. At least a subset of a plurality of sources 201 may be set as a source array. The source array may include a plurality of emitters on a common substrate. Focusing a plurality of charged particle beams from different charged particle devices simultaneously onto different regions of the same sample allows an increase in the area of ​​the sample 208 simultaneously exposed to the charged particle beam. Therefore, the increased sample area may be evaluated (or more generally processed) simultaneously. The charged particle devices in the array may be arranged adjacent to each other so that a corresponding plurality of beams are projected onto adjacent regions of the sample 208. Any number of charged particle devices may be used in the array. Preferably, the number of charged particle devices is in the range of 9 to 200. When referring to a single charged particle device, electron optical arrangement or system or array, each charged particle device in the array may be configured in any manner herein.Alternatively or additionally, one or more charged particle devices in the array may be configured to project a single beam.

[0071] Figure 7 Another example of a charged particle device 41 is schematically depicted. Features identical to those described above are denoted by identical reference numerals. For the sake of simplicity, these features are not referred to herein. Figure 7 For example, the source 201, the focusing lens 231, the objective lens array 401 and the sample 208 may be as described above. In this example, a macro collimator 270 (e.g., as a magnetic and / or electrostatic lens) is provided to replace the above referenced Figure 3 A deflector array of the type described. In other embodiments, a deflector array may alternatively or additionally be used to collimate the beam. In one arrangement, the converging lens 231 may include a single plate defining a beam limiting aperture array, in which a plurality of apertures are defined, wherein one or more associated macro-electrodes have a single aperture. Such a beam limiting aperture array and associated macro-electrodes may also form a converging lens array to focus the generated beam at an intermediate focus that desirably corresponds to the position of the collimator 270.

[0072] As described above, in some embodiments, the detector may be disposed between the objective lens array 401 and the sample 208. The detector may face the sample 208. Alternatively, as Figure 7 As shown, the detector 240 can be implemented such that the objective lens array 401 is located between the detector 240 and the sample 208.

[0073] In one embodiment, the deflector array 95 is disposed between the detector 240 and the objective lens array 401. In one embodiment, the deflector array 95 includes a Wien filter array so that the deflector array can be referred to as a beam splitter. The deflector array 95 is configured to provide a magnetic field and an electrostatic field. The electrostatic field and the magnetic field operate together to separate the charged particles projected to the sample 208 from the signal particles (e.g., secondary electrons) from the sample 208. The charged particles projected to the sample 208 are guided toward the sample by the filter. The operation of the field guides the signal particles from the sample to the detector 240.

[0074] In one embodiment, the detector 240 is configured to detect signal particles by referring to the energy of the charged particles (i.e., depending on the band gap), such a semiconductor-based type of detector. Such a detector 240 may be referred to as an indirect current detector. Signal particles (e.g., secondary electrons) from the sample 208 obtain energy from the field between the electrodes. The secondary electrons have sufficient energy once they reach the detector 240. In a different arrangement, the detector 240 may be an electron-photon converter, such as a scintillator array, such as a fluorescent strip between the beams, which is located upstream relative to the Wien filter along the primary beam path. The primary beam passing through the Wien filter array (magnetic and electrostatic strips orthogonal to the primary beam path) has substantially parallel upstream and downstream paths of the Wien filter array, while the signal electrons from the sample are guided to the scintillator array by the Wien filter array. The electron-to-photon converter may be photon-coupled to the photon-to-electron converter to convert any photons generated and emitted in the electron-to-photon converter. The photon-to-electron converter may be electrically connected to an electronic circuit device to process the detection signal. In different embodiments, the photon-to-electron converter may be inside or outside the charged particle device. In one embodiment, the photon coupling may be coupled through a photon transmission unit (eg, an optical fiber array) to a remote optical detector that generates a detection signal upon detection of the photon.

[0075] Projecting multiple beams comprising multiple charged particle beamlets onto a sample increases throughput relative to a single beam, but makes focus control more challenging, especially for increased fields of view, such as fields of view of up to 1 mm, 5 mm, 10 mm, 15 mm or even 20 mm. The focusing quality of each beamlet on the sample surface is determined by the position of the focal plane of the beamlet relative to the position on the sample surface where the beamlet is incident. If the position of the focal plane of the beam, such as the multibeam, is within an acceptable range for the corresponding portion of the sample surface, then the focusing quality of the beam, such as the beam, will be acceptable. Controlling the position of the focal plane of each beamlet relative to the sample surface is challenging because of the typical non-planar topography of the sample surface and the relatively large size of the intersection area between the multibeam paths of different beams, such as the multibeam (or grid), and the sample. The intersection area can be referred to as the area of ​​the beam grid that can be processed by multiple beams, such as the beam grid. The relatively large size of the intersection area may be due to the size of the field of view of the multibeam at the sample surface.

[0076] Information about the sample's surface topography can be obtained using sensors that measure the distance to various parts of the sample's surface. Figure 8 1 is a schematic bottom view (viewed in the upward beam direction) of a charged particle device, showing a multibeam 102 including a plurality of charged particle sub-beams and sensors 104A-104D, for example, located outside the route of the multibeam 102 (or away from the route of the multibeam 102), i.e., the multibeam during operation. The route of the multibeam 102 can be referred to as a multibeam path 103, which defines a common route for all sub-beams of the multibeam. Although an ideal representation of the multibeam path can be along the central route of the multibeam path toward the sample, the multibeam path can also define the outermost range of the multibeam. For example, the multibeam path 103 can define the farthest (or radially outermost) limit of the multibeam 102. All sub-beams of the multibeam 102 are contained in the multibeam path 103. Different sub-beams can be referred to as having respective sub-beam paths. Such sub-beam paths are within the multi-beam path. Therefore, the multi-beam path 103 defines a multi-beam volume between the charged particle device and the sample 208 containing the sub-beams and the sub-beam paths. There are no sub-beams outside the multi-beam path 103. In this example, four sensors 104A-104D are disposed at the distal end (or exterior) of the multi-beam path 103. The sensors 104A-104D can be described as being positioned spaced apart from the multi-beam path 103. Ideally, the sensors 104-D are as close to the multi-beam path as possible. However, if the sensors 104A-104D are located inside the multi-beam path 103, then due to design space conflicts, the sensors 104A-104D may be located outside the multi-beam path 103. A sensor located within the multi-beam path will block at least one beamlet path; therefore, the sensor will block at least one beamlet. To avoid such conflicts between the operation of the sensors 104A-104D and the multi-beam, the sensors are positioned such that they are spaced apart from the multi-beam path 103.

[0077] Each sensor 104A-104D faces the sample 208 and is capable of measuring a distance Zm between the sensor 104A-104D and the sample 208 (e.g., a distance between the sensor 104A-104D and a portion of the sample surface facing the sensor 104A-104D, e.g., along the direction of the multi-beam path 103). Each sensor 104A-104D provides output data representing the measurement result. In some arrangements, each sensor 104A-104D includes one or more capacitive sensors, optionally configured to operate in a differential mode. The output data from the sensors 104A-104D can be used, for example, by the controller 500 or a portion or constituent controller element of the controller 500 to control the positioning (including position and orientation) of the sample 208. This control of the position of the sample 209 improves the focusing quality of one or more beamlets on the sample 208. The purpose is to position the portion of the sample surface processed by each beamlet at or near the focal plane position of the beamlet.

[0078] Fig. 9 yes Figure 8 Schematic side view of a portion of a sample 208 downstream of an arrangement of the type shown. In this case, the multibeam 102 is directed along a multibeam path 103 from a charged particle device providing the multibeam 102 (which may include an objective lens array 401 including an objective lens and / or a detector module 402 having a detector; for example, the detector module is a detector such as a detector array, as described above with reference to Figure 1-Figure 7 108). In the example shown, which may be an idealized representation, the multibeam 102 has a common focal plane 108 for all beamlets. The focusing quality is acceptable for a range of positions of the sample surface that are close to the position of the focal plane 108. The range of positions may be defined by an upper limit 110 (e.g., an upper limit position) and a lower limit 112 (e.g., a lower limit position). The upper and lower limits depend on the focal range of the beams of the multibeam. The focal range of each beam may typically be on the order of ±300 nm or less. The focal range of the multibeam 102 will be the same, but as the multibeam 102 becomes larger (i.e., as the field of view increases), it will be more difficult to keep the surface of the sample 208 within the focal range because the flatness variations over the field of view will be greater. Fig. 9It is shown how variations in the topography of the sample 208 (which may be referred to as non-flatness, e.g., within a range with an upper limit of 10, 20, or even 50 microns) may cause focusing problems. Such focusing problems may result even if the sensors 104A-104D indicate that the sample 208 is perfectly positioned because the portion of the sample surface opposite the sensors 104A-104D is positioned at the focal plane 108. The topography of the sample 208 causes the portion of the sample surface within the multi-beam path 103 to be positioned outside the range of positions that produce acceptable focus quality. At the same time, the portion of the sample surface opposite the sensors 104A-104D is located at the focal plane 108. Depending on the direction of curvature of the sample surface in the multi-beam path 103 (convex or concave), the sample surface may be completely below or above the range of positions defined by the upper limit 110 and the lower limit 112. This situation may be addressed by obtaining a topography map of the sample surface in advance. However, obtaining such a map is time consuming. The topography of the sample surface may be real-time; the topography of the sample surface may change over time. Such changes may be referred to as drift. Drift in the time interval between obtaining the topography map and processing the sample using the multi-beam can cause focus errors. Position (e.g., spatial degrees of freedom (e.g., direction along a reference axis)) and / or orientation (e.g., angular degrees of freedom (e.g., angular displacement around a reference axis)) corrections can be applied to the sample. Position and / or orientation corrections to improve focus can be based on inaccurate topography maps. Embodiments of the present disclosure are directed to addressing these challenges.

[0079] In some embodiments, an electron optical device, such as disclosed elsewhere herein, is provided. The electron optical device may be part of, or configured to operate as, an evaluation device for evaluating (e.g., inspecting for defects) a sample 208 using multiple beams of charged particles (e.g., electrons). The electron optical device includes a stage for supporting a sample 208 having a sample surface. The stage may be configured as described above with reference to Figure 2 The stage may include, for example, an actuation stage 209. The stage is controllable to adjust the position and / or orientation of the sample 208. The electron optical device includes a charged particle device that projects multiple beams 102 along multiple beam paths 103 toward the sample 208, such as Fig. 9Schematically shown in . The multi-beam 102 includes a plurality of charged particle sub-beams. The sub-beams have routes within the multi-beam path 103 as described above. The routes may desirably be arranged in a grid, which may be referred to as a beam grid. These routes may be such that they impact the sample in a plurality of local regions defining the grid. The grid lines of the grid may define grid regions. Different grid regions may correspond to separate local regions of the sample surface within the field of view of the beam grid, which regions may be processed by, for example, different sub-beams of the multi-beam. In one embodiment, the grid lines may interconnect different beam paths. In another embodiment, the grid lines may pass through points of similar distances between two adjacent beams of the beam grid, desirably equidistant, such as on the sample surface (or a portion of the sample surface where two adjacent beams of the multi-beam are processed). The local regions defined by the grid lines may be sub-beam processable regions for processing by corresponding sub-beams of the multi-beam.

[0080] The multi-beam path 103 intersects the sample 208 in a multi-beam processable region 114. The multi-beam processable region may include a beamlet processable region of the beam grid. The multi-beam processable region 114 defines an area that is processable by the multi-beam for a given position of the multi-beam 102 relative to the sample 208 (ignoring scanning of beamlets over small distances, such as the distance between adjacent beamlets). The charged particle device may take the form described above with reference to Figure 3 and Figure 7 Any form of charged particle device 41 (which may also be referred to as an electron-optical arrangement or electron-optical train) is described.

[0081] The electron optical device may include a detector 240, which may be included in the detector module 402. The detector detects signal charged particles emitted from the sample 208. The detector generates a detection signal when the signal charged particles are detected. The detector may take the form of a detector as specifically described above. Figure 2-Figure 7 The detector 240 may be any of the forms described herein. The detector may be a detector having a specific reference to Figure 3-Figure 6 Processing sample 208 using multiple beams 102 may involve scanning multiple beams 102 over a sample surface and detecting signal electrons emitted from the sample surface using a detector. As described above, an image of a scanned portion of the sample surface may be generated using an image acquirer.

[0082] In some embodiments, the electron optical device includes a sensing system. The sensing system includes a plurality of sensors. Each sensor measures the position of a corresponding portion of the sample surface relative to the sensor outside the multi-beam processable area 114. These sensors can be configured to face the sample 208 and can measure the distance Zm between the sensor and the sample 208, as described above with reference to Fig. 9Described for sensors 104A-104D. The distance can be referred to as the height of the sample surface. The distance can be in a direction orthogonal to the common plane of the sample surface and / or in a direction parallel to the direction of the multi-beam path. The sensor can measure, for example, in the direction of the multi-beam path and / or desirably in a direction orthogonal to the common plane of the sample surface and / or in a direction substantially orthogonal to the plane of the main surface of the sensor, the main surface, for example, facing the sample surface in operation. Given the sample surface topography, the common plane can be the best fit plane. Each sensor can provide output data representing the measurement result. In some arrangements, each sensor 104A-104D includes one or more capacitive sensors, optionally configured to operate in differential mode. The sensor can be referred to as a proximal sensor. The sensing system can be mounted to maintain a fixed spatial relationship relative to the electronic optics of the charged particle device. For example, the sensing system can be supported directly or indirectly by the charged particle device, or the charged particle device and the sensing system can be supported together by a common support element. Therefore, the relative movement between the stage and the charged particle device will involve the corresponding relative movement between the stage and the sensing system. During relative movement between the stage and the charged particle device, the spatial relationship between the position on the sample surface measured by the sensor and the multi-beam processable area will remain substantially constant.

[0083] Figure 10-12 Example positions of sensors 120 - 124 of the sensing system relative to the multi-beam processable region 114 in the reference frame of the charged particle device are described. Figure 10-12 Projections of the positions of sensors 120-124 and multi-beam processable region 114 onto a plane parallel to sample 208 (or at least a common plane of the surface of sample 208) are depicted. Thus, these projections illustrate the relative positions of various features of the electron-optical device interacting with sample 208 (e.g., the positions of various portions of sample 208 being measured in the case of sensors 120-124, and the sample 208 being evaluated / inspected in the multi-beam processable region 114 in the case of multi-beam).

[0084] In some embodiments, Figure 10-12As illustrated and labeled in , the sensors of the sensing system include a set of proximal sensors 120A-120D. The proximal sensors 120A-120D are positioned proximal to the path of the multiple beamlets. Therefore, the proximal sensors 120A-120D are proximal to the multi-beam path 103. Each proximal sensor 120A-120D measures the position of a corresponding portion of the sample surface relative to the proximal sensor 120A-120D (e.g., the portion of the sample surface closest to (or facing) and / or directly below the proximal sensor 120A-120D). Each proximal sensor 120A-120D can measure the spacing between the proximal sensor 120A-120D and the corresponding portion of the sample surface. The portion of the sample surface measured by the proximal sensors 120A-120D is proximal to the multi-beam processable area 114.

[0085] In some embodiments, Figure 10-12 As illustrated and labeled in FIG. 1 , the sensors of the sensing system include one or more distal sensors 121-124. Each distal sensor is positioned further (i.e., farther away) from the multi-beam path 103 (or the path of the sub-beams) than the proximal sensors 120A-120D. The or each distal sensor 121-124 is configured to measure a position of a corresponding portion of the sample surface relative to the distal sensor 121-124. Each distal sensor 121-124 can measure a spacing between the distal sensor 121-124 and the corresponding portion of the sample surface. The portion of the sample surface measured by the distal sensors 121-124 is further away from the multi-beam processable area 114 than the portion of the sample surface measured by the proximal sensors 120A-120D.

[0086] In one embodiment, the primary function of the proximal sensors 120A-120D may be to provide direct input to the control system for positioning the actuation stage 209. In contrast, the primary function of one or more distal sensors 121-124 may be to provide calibration information, such as to provide or refine a topographic map of the surface of the sample 208 that may be used to calibrate or improve the positioning of the actuation stage 209 based on the output from the proximal sensors 120A-120D. Thus, one or more distal sensors 121-124 may be referred to as calibration sensors. However, as described below, in some embodiments, both the proximal sensors 120A-120D and the distal sensors 121-124 are used to obtain topographic information about the sample surface and, therefore, for calibration purposes.

[0087] Proximal sensors 120A-120D and distal sensors 121-124 may be positioned at substantially the same distance, such as in the same plane, from stage and sample 208. Alternatively, two or more of proximal sensors 120A-120D and distal sensors 121-124 may be positioned at different distances from stage and sample 208.

[0088] The proximal sensors 120A-120D and the distal sensors 121-124 can be used to obtain topographic information about the sample surface. The topographic information includes information about the shape of the sample surface. For example, in a Cartesian coordinate system, the Z axis is parallel to the center path of the multi-beam path 103 and / or geometrically: the principal axis of the multi-beam and / or perpendicular to the nominally flat sample on the stage. In such a reference system, the topographic information can include a graph of the position along the center path or the Z position (which can also be referred to as the height) of the sample surface as a function of X and Y. The gradient (rate of change) of Z as a function of direction in the XY plane can be referred to as, for example, the tilt of the sample surface relative to the multi-beam path 103.

[0089] The proximal sensors 120A-120D measure portions of the sample 209 that are away from or outside the multi-beam processable region 114. However, the portion of the sample 209 measured by the proximal sensors 120A-120D is positioned near and around the multi-beam processable region 114, for example, as disclosed in US2011 / 0193574, which is incorporated herein by reference at least to date, to generate a height map of at least a portion of the sample surface. Therefore, the proximal sensors 120A-120D are suitable for determining topographic information about the sample surface near or in the multi-beam processable region 114. The combination of the proximal sensors 120A-120D can be used to obtain tilt information about the sample surface in the multi-beam processable region 114. The proximal sensors 120A and 120B (or the proximal sensors 120C and 120D) can be used to obtain information about the tilt relative to the Y-axis, for example, about the Y-axis in the multi-beam processable region 114, for example, about the axis in a first direction of a common plane of the sample surface. Similarly, the proximal sensors 120A and 120D (or the proximal sensors 120B and 120C) can be used to obtain information about the tilt relative to the X-axis (e.g., about the X-axis) in the multi-beam processable area 114, such as about an axis that is angled (e.g., orthogonal) in a second direction in the common plane of the sample surface relative to a first axis in the common plane. By positioning one or more distal sensors 121-124 further away from the multi-beam, information about the sample surface topography further away from the multi-beam processable area 114 can be obtained.

[0090] refer to Fig.10For example, the distal sensor 121 can be used to obtain information not only about the height of the sample surface directly below (or facing) the distal sensor 121, but also about the tilt in the area 115 outside the multi-beam processable area 114. That is, the distal sensor 121 can be used to obtain information about the height of the portion of the sample surface facing the distal sensor 121 and the tilt of the adjacent portion away from the processable area 114 (which can be considered as the outer area 115 outside the multi-beam processable area 114). Passing through the multi-beam processable area 114 is a route represented by a dotted line. The route divides the multi-beam processable area 114 into two parts. The two parts of the multi-beam processable area can have similar areas, or even the same areas, so that the route divides the multi-beam processable area 114 into two. When the route extends outward from the multi-beam processable area 114, the distal sensor 121 (which can be referred to as a primary distal sensor) can be positioned in the direction of the route (or primary route), such as on the route. The primary distal sensor 121 can be on the route. The combination of measurements from distal sensor 121 and proximal sensors 120A and 120B may provide information about the tilt in region 115 relative to the X-axis and the Y-axis.

[0091] refer to Fig.11 , for example, as referenced Fig.10The distal sensor 121 (or primary distal sensor 121) shown and described can be used to obtain information about the height of the portion of the sample surface facing the distal sensor 121 and the tilt of the adjacent portion away from the processable area 114 (which can be considered in the outer area 115 outside the multi-beam processable area 114). The primary distal sensor 121 can be located on the route. Similarly, the distal sensor 123 can be used to obtain information not only about the height of the sample surface directly below the distal sensor 123, but also about the tilt in the area 116 outside the multi-beam processable area 114. That is, the distal sensor 123 (or secondary distal sensor) can be used to obtain information about the height of the portion of the sample surface facing the secondary distal sensor 121 and the tilt of the adjacent portion away from the processable area 114 (which can be considered in the outer area 116 outside the multi-beam processable area 114). Passing through the multi-beam processable area 114 is a route represented by a dotted line, such as a secondary route. The route divides the multi-beam processable area 114 into two parts. The two portions of the multi-beam processable area may have similar areas, or even the same areas, such that the secondary route divides the multi-beam processable area 114 into two. The secondary route may have different directions in a common plane of the multi-beam processable area 114, such as in a common plane of the multi-beam processable area 114; for example, the secondary route may be orthogonal to the primary route. The secondary distal sensor 123 may be located in the direction of the secondary route, such as on the route, as the route extends outward from the multi-beam processable area 114. The secondary distal sensor 123 may be on the secondary route. As described above, the combination of measurements from the distal sensor 121 and the proximal sensors 120A and 120B may provide information about the tilt relative to the X and Y axes in the area 115. The combination of measurements from the distal sensor 123 and the proximal sensors 120B and 120C may provide information about the tilt relative to the X and Y axes in the area 116. (It should be noted that the numerical references to the sensors 121, 123 are convenient labels and do not necessarily indicate the relative priority or importance of the sensors).

[0092] Reference Fig.12 ,and Fig.11 The common features are Fig.11The same description provided. In addition, additional remote sensors 122 and 124 are provided, which may be referred to as third sensor 122 and fourth sensor 124, respectively. The third sensor 122 may be positioned in the direction of the primary path relative to the multi-beam processable area 114, or even on the primary path. The third sensor 122 may be positioned on the side of the multi-beam processable area 114 opposite to the primary sensor 121. The fourth sensor 124 may be positioned in the direction of the secondary path relative to the multi-beam processable area 114, or even on the secondary path. The fourth sensor 124 may be positioned on the side of the multi-beam processable area 114 opposite to the second sensor 123. (It should be noted that the numerical references to the sensors 121, 122, 123, 124 are convenient labels and do not necessarily indicate the relative priority or importance of the sensors).

[0093] The sample 208 can be processed (e.g., evaluated, such as inspected or measured) by the multi-beam by moving the multi-beam along a processing path (e.g., one of a primary route and a secondary route) over the sample 208. This can be achieved by providing relative movement between the multi-beam processable area 114 and the sample 208, such as by a moving stage. The multi-beam processable area 114 moves along the processing path, such as represented by one of the dashed lines (e.g., the primary route and / or the secondary route), such as in a Cartesian reference frame, such as in the reference frame of the sample 208, in a direction corresponding to the Y axis. A remote sensor can be used to obtain topographic information about the sample surface in a selected portion of the processing path before the multi-beam processable area 114 reaches the selected portion of the processing path. Thus, the topographic information can be used to improve processing in time. The position and / or orientation (e.g., Z position or height) of the sample 208 can be adjusted, for example, along the direction of the multi-beam path, for example, based on the topographic information obtained about a selected portion of the processing path relative to the multi-beam path, such as when the multi-beam processable area 114 reaches the selected portion. This adjustment can improve the focus during processing (or at least improve the focus quality of the multi-beams, as well as the focus variation of different beams of the beam array). For example, it can improve Fig. 9 In reference Fig. 9 In the method shown and described, the sample 208 is positioned based solely on aligning the sample surface to coincide with the focal plane 108 at a location corresponding to the proximal sensor. Fig. 9In the case shown, the sample 208 can be positioned, for example, at a distance further upstream (e.g., upstream of the multi-beam path) such that at least a portion of a portion of the sample surface in the multi-beam processable region 114 is moved such that a portion of the sample corresponding to the multi-beam processable region 114 is within a position range between, for example, an upstream position and a downstream position. That is, the position range is defined by the upstream 110 and the downstream 112. The portion of the sample corresponding to the multi-beam processable region 114 can be positioned within the position range, rather than being located far from the position range (i.e., outside the range).

[0094] exist Fig.11 In an example of the method, if the multi-beam processable region 114 moves over the regions 115 and / or 116 after the regions 115 and / or 116 have been measured using the remote sensors 121 (e.g., primary remote sensors) and / or 123 (e.g., secondary remote sensors), the topographic information obtained by those remote sensors can be used to improve focus as the multi-beam processable region 114 passes over the regions 115 and / or 116. Because the topographic measurements of the regions 115 and / or 116 are taken just before the same regions are multi-beam processed (e.g., when the multi-beam processable region 114 moves along an earlier portion of the processing path), the method can be referred to as obtaining topographic information about the sample surface in "real time." The real-time nature of the method avoids or reduces the need to pre-acquire a topographic map in a separate process. There is no longer a need to scan the surface using a sensor or otherwise generate a sample map. There is no longer a need for a separate pre-scan to generate a sample map. As a result, sample processing time can be reduced by the time used to generate a sample map. This time can be used for sample processing, thereby increasing throughput. At the same time, topographic information can be obtained far enough in advance to allow appropriate position / orientation corrections to be made without slowing down the processing performed by the multi-beam.

[0095] As mentioned above, Fig.12 An arrangement is shown in which additional distal sensors 122 and 124 (e.g., a third sensor and a fourth sensor) are provided. These additional distal sensors 122 and 124 provide flexibility for moving the multi-beam processable area 114 in different directions on the sample surface (e.g., opposite directions of relative movement between the sample 209 and the multi-beam path 103, such as along one of the primary path and the secondary path). These additional distal sensors 122 and 124 provide flexibility for moving the multi-beam processable area 114 while still being able to obtain relevant topographic information of portions of the sample surface before multi-beam processing of those portions. Further details on options for geometrically arranging the sensors are described later in the following description.

[0096] Figure 13-Figure 17 Describes the use Fig.11The illustrated sensor arrangement processes different stages of an embodiment of a sample 208. In each figure, the positions of different sensors 120, 121, 123 (e.g., the proximal sensor 120 and the primary sensor 121 and the secondary sensor 123) are projected onto a plane of the sample 208 (e.g., a common plane of the sample surface) to show the relative positions of the portions of the sample surface measured by the sensors and the multi-beam processable region 114. In this example, the sample 208 is processed by moving the multi-beam processable region 114 along a processing path that includes a series of parallel routes 132, 133. Such parallel routes may correspond to reference Fig.11 or Fig.12 (It should be noted that this description involves the multi-beam processable area 114 and the sample surface moving relative to each other so that the multi-beam processable area 114 (or alternatively represented as a multi-beam path 114) passes through the surface of the sample in a series of parallel paths 132, 133 in the reference system of the sample. In the following description, for convenience of expression, the multi-beam processable area 114 is expressed as such relative movement between the multi-beam processable area 114 on the sample surface and the sample surface in the reference system of the sample.

[0097] Fig.13 A stage is described which may be an initial stage of an embodiment, wherein a multi-beam processable region 114 (or alternatively represented as a multi-beam path) approaches a sample 208 from a region outside the sample 208 (e.g., in a reference frame of the sample 208). In the initial stage, the sample is positioned so that the sample surface does not face the multi-beam path 103. In this stage, the multi-beam processable region 114 and three of the four proximal sensors 120 are not on the sample 208, while the distal sensors 121 and 123 are on the sample 208. That is, the sample is positioned to face the distal sensors 121, 123 and one of the four proximal sensors 120, such as the proximal sensor 120B that is positioned closest to the distal sensors 121, 123 in the reference frame of the distal sensors, such as between the two distal sensors 121, 123. The distal sensors 121 and 123 are able to obtain detailed information about the sample topography at an early stage of processing the sample compared to a case where there are no distal sensors.

[0098] Fig.14 Depicting and Fig.13132, 133. The arrows associated with the routes 132, 133 indicate the relative movement direction of the multi-beam processable region 114 along the routes 132, 133, for example, in the reference frame of the sample. In this example, the surface of the sample 208 faces the distal sensors 121, 122, the proximal sensors 120A, 120B, 120C, 120D, and the multi-beam path 102. The sample topography in the region 115 (or the advancing region relative to the multi-beam processable region) is measured by the distal sensor 121 and the optional proximal sensors 120A and 120B while a portion of the sample surface at the multi-beam processable region 114 is processed. In the same route 132, the portion of the sample surface at the multi-beam processable region 114 is region 115 before the multi-beam processable region 114; that is, before the multi-beam processable region 114 moves on the sample surface measured by at least the distal sensor, and further along a portion of the route 132 relative to the multi-beam processable region 114 becomes region 115. At the same time, the sample topography in region 116 can be measured by the distal sensor 123 and the optional proximal sensors 120B and 120C. Region 116 refers to the portion of the sample in a route 133 adjacent to route 132 relative to the multi-beam processable region 114. In this example, topographic information about substantially all of this adjacent route 133 can be obtained before the multi-beam begins processing this route 133 (or alternatively, indicating that the multi-beam processable region 114 moves on the sample surface along route 133). Figure 15-17 Schematically shows Fig.13 and Fig.14 How processing can be performed at the level of the entire sample 208 to gradually enter the later stages of processing. Figure 15 to Figure 17 Each graph in can be Fig.15 , Fig.16 Then Fig.17 The order represents successive stages of processing. The shaded area 134 in each of these figures represents a portion of the sample 208 for which topographic information has been obtained using at least the remote sensors 121, 123. The shaded area 134 shows how topographic information is obtained from areas of the sample surface prior to the location of the multi-beam processable area 114 as the multi-beam processable area 114 moves along the processing path over the sample surface. The shaded area 134 includes areas of the sample surface that are both within the same route 132 as the location of the multi-beam processable area 114 and within a next route 133, such as a route that the multi-beam processable area 114 has not yet traversed. (Note that the next route 133 may correspond to an adjacent route 133 that is directly to one side of the same route 132, such as adjacent to the same route 132, further along the x-axis in the Cartesian coordinate system of the sample surface; or as Figures 15 to 17as shown in any of the , located to the right of the same route 132).

[0099] Functions such as those described above can be implemented using a control system 500. The control system 500 controls the electronic optical device to perform the functions. The control system 500 may include or be implemented using the above reference Figure 1 The control system 500 can be composed of a controller 50 of any form described. The control system 500 can enable the electronic optical device to perform functions through a console, a charged particle device and / or a detector. The control system 500 may include a single unit configured to perform all control functions, or may include a distributed system of units that together allow the desired functions to be achieved. The control system 500 can be implemented at least in part by a computer. Any suitable combination of elements (e.g., CPU, RAM, data storage device, data connection, sensor, etc.) can be provided and appropriately programmed to achieve the specified function. Any reference to a device, device or system configured to perform a function herein is intended to cover the situation where the control system 500 is configured to enable the function to be performed (e.g., by being appropriately programmed to provide a control signal that enables the function to occur).

[0100] In one embodiment, the control system 500 controls the charged particle device to process the sample surface in the multi-beam processable area 114. The processing may include evaluating or inspecting the sample surface using multiple beams. As described above, this can be done by using the detector 240 to detect signal electrons emitted from the sample surface.

[0101] In one embodiment, the control system 500 controls the console 209 to move the multi-beam processable area 114 along a process path in the reference frame of the sample 208. When the multi-beam processable area 114 is positioned to surround the area, an area on the sample surface can be processed by multiple beams. Thus, moving the multi-beam processable area 114 along the process path allows processing of an area larger than the area of ​​the multi-beam processable area 114. As described above, Figure 13-Figure 17 As illustrated in , the processing path can be selected to allow a large portion of the sample surface to be processed. Alternatively, one or more local regions of interest can be more specifically targeted. Obtaining topographic information in real time in an area close to the multi-beam processable area 114 can more effectively locate the local region of interest. For example, there is no need to obtain a topographic map of the entire sample 208 in advance, nor is it necessary to know in advance which areas are targeted. The real-time method provides the flexibility to obtain only the topographic information required for a specific evaluation / inspection task. For ease of visualization, reference is made to the multi-beam processable area 114 that moves along the processing path relative to the sample 208. In practice, when considered in the reference frame of the electron optical device, the relative movement between the multi-beam processable area 114 and the sample 208 is typically provided primarily or entirely by moving the sample 208 rather than the multi-beam processable area 114.

[0102] In one embodiment, the control system 500 controls the sensing system to use at least one or more remote sensors 121-124 to obtain morphological information about the sample surface in a selected portion of the processing path before the multi-beam processable area 114 reaches the selected portion of the processing path. The above-mentioned areas 115 and 116 are examples of such selected portions relative to the multi-beam processable area 114. Area 115 can be referred to as the forward area 115; area 116 can be referred to as the side area 116. That is, areas 115 and 116 (or the forward area 115 and the side area 116) move on the sample surface so that morphological information of various portions of the sample surface can be obtained, and the various portions of the sample surface correspond to the position of the forward area 115 and / or the side area 116 on the sample surface along the processing route 132 relative to the multi-beam processable area 114. The control system 500 can be configured to control the sensing system and the charged particle device to obtain morphological information and simultaneously process the sample surface in different corresponding portions of the processing path. This is in Fig.14 , for example, where topographic information can be obtained in regions 115 and 116 while the sample is being processed in multi-beam processable region 114. The advantages of this real-time approach have been discussed above.

[0103] More details are now given regarding the options for positioning the sensor.

[0104] As described above, to achieve real-time functionality, the one or more distal sensors 121-124 include at least one distal sensor 121, 123 located along the processing path before the multi-beam processable region 114. Thus, the positioning of the sensors may depend on the details of the processing path used.

[0105] In some embodiments, Figure 13-Figure 17 , the processing path includes multiple routes 132, 133 (for ease of reference, may be referred to by reference numeral 132). Each route 132 is a portion of the processing path. The routes 132 can be parallel to each other. The routes 132 can be straight (as shown) or curved, or include straight and curved elements. The routes 132 are offset relative to each other. The offset is the offset direction on the sample surface, for example, indicating the displacement of the multi-beam processable area 114 and the sample relative to each other. Figure 13-Figure 17The offset direction in the example shown is horizontal (from left to right) in the plane of the page. The offset dimension may be substantially equal to or less than the dimension (e.g., width) of the multi-beam processable area 114 parallel to the offset direction. The strips 130 (e.g., of the sample surface) processed by moving the multi-beam processable area 114 along adjacent routes will therefore be continuous or partially overlapping. The control system 500 may cause the multi-beam processable area 114 to move sequentially along the routes. The control system 500 may shift the multi-beam processable area 114 and the routes 132 relative to each other between the processing of different routes 132 of the processing path, desirably in the offset direction across the sample surface. The control system 500 may be configured to shift the sample 208 and the grid (and therefore the multi-beam processable area 114) relative to each other between different routes of the processing path through the sample surface. The control system 500 may be configured to sequentially shift the sample 208 and the grid (and therefore the multi-beam processable area 114) relative to each other between the desired routes. In the example shown, the routes 132 are depicted as arrows, all pointing downward to indicate the direction of movement of the multi-beam processable area 114 along the routes. In other embodiments, the routes 132 may alternate in direction to reduce the total distance the stage needs to be moved to process all routes 132.

[0106] In some embodiments, one or more distal sensors 121-124 include at least one distal sensor 121 positioned relative to the multi-beam processable region 114 to measure a portion of the sample surface in the same route 132 as the multi-beam processable region 114 (e.g., when multiple beams process different portions of the sample surface in the same route). Thus, one or more distal sensors 121-124 may include at least one distal sensor positioned relative to the grid and the processing path to measure a portion of the sample surface in the same path. In the case where the distal sensor 121 in the same route 132 is located before the multi-beam processable region 114, the distal sensor 121 may be referred to as a forward sensor 121 or in front sensor 121. Such a forward sensor 121 is positioned to measure a portion of the sample surface in the same route 132 before the multi-beam processable region 114 moves over the portion of the sample surface, and, for example, Fig.14 Example in. Fig.10 An exemplary arrangement is depicted in which the only distal sensor provided is the forward sensor 121 . Figure 11-Figure 12 An exemplary arrangement with such a forward sensor 121 and other distal sensors is depicted. (Note that if the direction of relative movement between the multi-beam processable region 114 and the sample surface is different, for example, in opposite directions along the route, or the path is different from Figures 13 to 17If the directions of the paths shown are orthogonal, another of the distal sensors 122, 123, 124 can be used as a forward sensor. The description here about the forward sensor can be correspondingly applied to another arrangement in which any of the distal sensors 122, 123, 124 is used as a forward sensor.

[0107] In some embodiments, at least one of the distal sensors 121-124 includes a distal sensor 121 that is substantially centrally positioned relative to a dimension of the multi-beam processable area 114 that is perpendicular to the relative movement of the multi-beam processable area 114 along the route 132. Thus, the distal sensor can be substantially centrally positioned relative to the dimension of the grid proximate to the sample surface orthogonal to the multi-beam path. Figure 10-12 The forward sensor 121 is shown positioned in this manner. Centrally positioning the distal sensor 121 in this manner allows the distal sensor 121 to directly obtain topographic information about a portion of the sample surface over which a central portion of the multi-beam processable area 114 will pass. However, the forward sensor 121 can be positioned off-center and still be able to obtain useful topographic information. The forward sensor 121 is desirably positioned to be able to measure at least a portion of the sample surface over which a portion of the multi-beam processable area 114 will pass during movement along the route 132 of the processing path, such as corresponding to the advancement zone 115.

[0108] In some embodiments, at least one distal sensor 121-124 includes a rearward sensor 122 (which is alternatively referred to as a tail sensor 122) and a forward sensor 121. The rearward sensor 122 and the forward sensor 121 can be positioned to simultaneously measure portions of the sample surface on opposite sides of the multi-beam processable area 114. The rearward sensor 122 and the forward sensor 121 can be displaced from the grid along the same route. This type of exemplary configuration is Fig.12 1. In this view, the rearward sensor 122 and the forward sensor 121 are located on opposite sides of the multi-beam processable area 114. Providing both the rearward sensor and the forward sensor ensures that the distal sensor is always located in front of the multi-beam processable area 114, regardless of the process direction of the route 132. If the process direction is reversed, the roles of the rearward sensor and the forward sensor are reversed, with the forward sensor becoming the rearward sensor and the rearward sensor becoming the forward sensor.

[0109] In some embodiments, one or more distal sensors 121-124 include side sensors 123, 124 positioned to measure a portion of the sample surface in one of the routes 133 before the multi-beam processable region 114 moves over the portion of the sample surface and when the multi-beam processable region 114 is within a different one of the routes 132. The portion of the sample surface facing one of the side sensors 123 can correspond to the side region 116 relative to the multi-beam processable region 114. Thus, the side sensor 123 can be positioned to measure a portion of the sample surface in a route 133 that is different from the route 132 in the multi-beam path 103. Fig.11 and Fig.12 An example configuration with such side sensors 123, 124 is shown. Thus, the provision of side sensors 123, 124 allows topographic information about a portion of the sample surface in a route 132 to be obtained before processing of the route even begins (when the multi-beam 102 is processing an adjacent route 132). The side sensors 123, 124 can be positioned to measure a portion of the sample surface that is substantially aligned with the center of the multi-beam processable area 114 in a direction perpendicular to the relative movement of the multi-beam processable area 114 along one of the routes (e.g., as shown in FIG. 1 ). Fig.11 and Fig.12 As shown, the side sensors 123, 124 can measure a portion aligned in a horizontal direction with the center of the multi-beam processable area 114.) Thus, the one or more distal sensors can include a side sensor positioned away from the grid in a direction orthogonal to the processing path, desirably on a different side of the grid than the forward or rearward sensors.

[0110] In some embodiments, Fig.12 As illustrated, two side sensors 123, 124 are provided, which may be referred to as a first side sensor 123 and a second side sensor 124. The first side sensor 123 and the second side sensor 124 may be positioned to simultaneously measure portions of the sample surface on opposite sides of the multi-beam processable area 114, desirably within a different route 132 than the route that the multi-beam processable area 114 is currently located. Thus, the second side sensor 124 may be positioned on an opposite side of the grid from the first side sensor 123.

[0111] The spatial distribution of the set of proximal sensors 120 is not particularly limited. Providing multiple proximal sensors makes it possible to obtain tilt information and allows reliable Z measurements even towards the edge of the sample 208. In some embodiments, the set of proximal sensors includes four proximal sensors positioned to measure four corresponding portions of the sample surface defining the vertices of the quadrilateral shape. Figure 10-Figure 14As shown, the quadrilateral can be a rectangle, such as a square. The quadrilateral can be centered on the multi-beam processable area 114 (so that the corresponding sensors 120 are positioned to define the vertices of the quadrilateral centered on the multi-beam, such as the center path of the multi-beam path 103). In this type of embodiment, the one or more distal sensors 121-124 can include a first distal sensor 121, which is positioned to measure a corresponding portion of the sample surface, which is parallel to the first side of the rectangle (i.e., the first side of the rectangle is defined by the sensor 120). Figure 10-Figure 14 One of the sides of the rectangle formed by the projection positions of the proximal sensors 120A-120D in the sample surface is aligned with the center of the rectangle in the direction of the portion defining the vertices of the rectangle of the sample surface respectively.

[0112] In some embodiments, the one or more distal sensors further include a second distal sensor 123 positioned to measure a portion of the sample surface aligned with the center of the rectangle in a direction parallel to a second side of the rectangle. The second side may be orthogonal to the first side. Figure 11-Figure 14 In the example of FIG. 1 , the second side of the rectangle is one of the vertical sides of the rectangle formed by the projection positions of the proximal sensors 120A- 120D.

[0113] As described above, it is desirable to use topographic information about the sample surface in the multi-beam processable region 114 to correct for unevenness during multi-beam processing. In the above-described embodiments, topographic information is obtained in real time using a distal sensor (in combination with a proximal sensor) located before the multi-beam processable region 114. In other arrangements, a topographic map of the entire surface may be obtained in advance. The Z position of a portion of the sample surface corresponding to the multi-beam processable region 114 (e.g., the displacement of the sample surface in a direction parallel to the multi-beam path) may be controlled by reference to the output from the proximal sensor. For example, in Figure 8 In an arrangement of the type shown, the Z position can be controlled by reference to the output from sensor 104A, applying a correction derived from previously acquired topographic information. The desired correction is:

[0114]

[0115] Where: Z waf (X, Y) is the Z position (wafer height) of the sample as a function of the horizontal coordinate; (X EO , Y EO ) is the XY position corresponding to the center of the electron-optical (EO) and multi-beam processable region 114; and dX and dY are the spacings along the X and Y of the sensors (dX is the spacing between sensors 104A and 104B and between 104C and 104D; dY is the spacing between sensors 104A and 104D and between 104B and 104C).

[0116] If the topological information is obtained simply by scanning a single sensor across the sample surface to obtain a map of the Z position of the stage controlled by a stage measurement system (e.g. an interferometer system), then waf (X, Y), then will include inaccuracies of the stage measurement system (eg due to mirror non-flatness in the interferometer system), which is undesirable. As shown in expression (1) above, the desired correction only involves non-flatness in the sample.

[0117] One way to reduce or avoid inaccuracies in a stage measurement system is to use the differences between measurements from different proximal sensors. For example, in the example discussed above, where the outputs from sensors 104A-104D are represented as Z and A , Z B , Z C , Z D , instead of using only the output Z A , the difference Z can be used, which is independent of the inaccuracy of the stage measurement system D -Z A , Z C -Z A and Z B -Z A However, the weakness of this method is that it is not sensitive to all types of sample non-flatness. Fig.18 As schematically shown in FIG. 1 , this method will not be able to detect certain periodic features or characteristics of the sample's surface topography related to positioning, such as the geometric arrangement of the different sensors 120A-120D relative to the multi-beam path 103. For example, the proximal sensors are arranged to form a Figure 8 In the case of a rectangle with sides aligned along X and Y as shown, this method cannot detect Z waf The spatial Fourier component of (X, Y) has a wavelength equal to dX along the X direction or dY along the Y direction. Fig.18 As can be seen in , it is desirable to correct for such spatial components since they may cause significant focusing errors. Preliminary numerical studies have shown that local sample non-flatness with such spatial components of the order of H will result in an error of H / 4 in the calculated sample surface height correction.

[0118] Similar to the reference above Figure 10-Figure 17 In the manner of the embodiments discussed, the above problems are solved according to the embodiments of the present disclosure by providing one or more additional, optionally remote sensors. Figure 19-21 Describe the above reference Figure 10-Figure 17The electron optical device and method described herein are variations of the embodiments. The electron optical device according to the present embodiment comprises a stage configured to support a sample 208, a charged particle device configured to project multiple beams toward the sample 208, and a sensing system comprising multiple sensors. The stage, the charged particle device and / or the sensing system may be configured and / or arranged as described above with particular reference to Figure 10-Figure 17 The embodiments described herein can be operated in any manner. Figure 19-21 The arrangements described and shown may be used with reference to Figure 10-Figure 17 The same features are described and shown unless stated to the contrary.

[0119] Fig.19 and Fig. 20 The projection of the position of sensors 141-145 and multi-beam processable area 114 of the class of this embodiment is depicted onto a plane substantially parallel to sample 208. The projection shows the relative positioning of sensors 141-145 and multi-beam processable area 114 when viewed in a direction toward sample 208 and parallel to the major axis of multi-beam 102 (generally vertically downward). In this example, sensors 143, 142, 144, and 145 are positioned at the same plane as the sample 208. Figure 8 The sensors 104A-104D are positioned in the same manner.

[0120] In such embodiments, the plurality of proximal sensors include at least a first sensor 141, a second sensor 142, and a third sensor 143. (The first sensor 141 may correspond to the distal sensor 121 (or primary distal sensor). The second sensor 142 may correspond to the proximal sensor 120B. The third sensor 143 may correspond to the proximal sensor 120A. The first sensor 141 relative to the proximal sensors 142 to 145 or 120A-120D may be referred to as a "fifth sensor"). The first sensor 141, the second sensor 142, and the third sensor 143 are positioned so that in the projection of the position of the sensors and the multi-beam processable region 114 onto a plane parallel to the sample 208, as shown in FIG. Fig.19 As shown, vector 151 connects the positions of first sensor 141 and second sensor 142. Vector 151 is substantially equal to or opposite to vector 152 connecting the position of third sensor 143 to the center of multi-beam processable region 114 (or the intersection of the center path of multi-beam path 103 and a plane parallel to the sample onto which the positions of sensors 141 to 145 are projected). Vector 152 may be referred to as a proximal vector between one of the proximal sensors 143 and the center of multi-beam processable region 114. Vector 151 may be referred to as a distal vector between a distal sensor or first sensor 141 and the center of multi-beam processable region 114.

[0121] The equal or opposite nature of the distal vector 151 and the proximal vector 152 makes it possible to use the first sensor 141 and the second sensor 142 to determine the height difference between two locations on the substrate surface that have the same spatial relationship relative to each other as the spatial relationship between the third sensor and the center of the multi-beam processable area 114. This makes it possible to derive the height of the sample surface at the center of the multi-beam processable area 114 from a single measurement by the third sensor 143, even though no sensor can directly measure the height of the sample surface at the center of the multi-beam processable area 114. The measurement by the third sensor 143 can be considered a calibration or correction. The third sensor 143 can be referred to as a calibration sensor.

[0122] The correction term given by the above expression (1) corresponds to Fig.19 The proximal vector 152 is shown. Figure 8 The arrangement of the first sensor 141 provides the additional option of measuring the distal vector 151 which is the same as or opposite to the proximal vector 152. When the multi-beam processable area 114 is located at any portion of the sample surface (X EO , Y EO ), the height difference or Z position of the sample surface measured by the second sensor 142, Z2, for example, relative to the facing portion of the sample surface, and the height difference or Z position of the sample surface measured by the first sensor 141, Z1, for example, relative to the facing portion of the sample surface, can be written as follows:

[0123]

[0124] When the multi-beam processable region 114 is positioned relative to the sample at what may be referred to as a calibration position When , such a difference in, for example, height, provides the desired correction. For example, the first sensor 141 and the second sensor 142 can be scanned relative to the sample 208 to obtain a data set representing corresponding maps (e.g., height maps) Z1(X,Y) and Z2(X,Y). Shifting this data set by the shift vector provides corresponding shifted maps, such as height maps, of the sample surface Z′1(X,Y) and Z′2(X,Y). In this particular example, if the shift vector is the corresponding shift map, then using the output from the third sensor 143 to obtain Z waf (X EO , Y EO ) required correction. The shift vector of represents a shift of half the distance between the first sensor 142 and the third sensor 143 in the X direction and a shift of half the distance between the second sensor 142 and the fourth sensor 144 in the Y direction. Due to the symmetry of the positions of the first sensor 141, the second sensor 142, and the third sensor 143, in the example shown, the shift vector has the same magnitude as the far-end vector 151 and the near-end vector 152. In other embodiments, the shift vector may have a different magnitude than the far-end vector 151 and the near-end vector 152. The relationship between the shift maps can be expressed as

[0125]

[0126] Expression (3) shows that the difference between the shift maps is Expression (1). Therefore, the shift map obtained from the output of the first sensor 141 and the second sensor 142 provides correction data that makes it possible to use the output from the third sensor 143 to infer the unevenness in the multi-beam processable area 114 during subsequent processing. Then, even if Fig.18 In the case of unevenness of the type shown, the output from the third sensor 143 can also be used to accurately control the position (e.g., height) of the sample without interference from inaccuracies of the stage measurement system such as mirror unevenness. The correction data can be obtained in real time (while the multi-beam is performing processing) or in advance (before the multi-beam begins processing). Although this specification refers to the first sensor 141 (or the fifth sensor) being the primary distal sensor 121, any of the distal sensors 122, 123, 124 can be used as the first sensor 141, where the relevant specific proximal sensor and its function are mapped as described relative to the primary distal sensor 121.

[0127] In some embodiments, a method such as Fig.21 The method shown can be implemented using a control system 500 to control the console and sensing system.

[0128] In step S1 , a multi-beam processable area 114 is positioned at a first location on a sample surface.

[0129] In step S2, when the multi-beam processable region 114 is in a first position, a measurement of the sample surface is obtained using the first sensor 141 and the second sensor 142.

[0130] In step S3, when the multi-beam processable area 114 is in the first position, a correction value is generated using the measurement values ​​obtained by the first sensor 141 and the second sensor 142. For example, the correction value may include a difference between the height of the sample surface measured by the first sensor 141 and the height of the sample surface measured by the second sensor 142.

[0131] In step S4, the multi-beam processable area 114 is moved to a second position on the sample surface. Preferably, the second position of the multi-beam processable area 114 is such that the third sensor 143 is positioned to measure substantially the same portion of the sample surface as the first sensor 141 was positioned to measure when the multi-beam processable area 114 was in the first position. This means that the correction values ​​generated in step S3 will be applicable to obtain information (e.g., height) about the sample surface at the center of the multi-beam processable area 114 at the second position from the measurement of the third sensor 143.

[0132] In step S5 , when the multi-beam processable area 114 is located at, for example, a second position on the sample surface, a measurement result of the sample surface is obtained using the third sensor 143 .

[0133] In step S6, by using the measurement results obtained by third sensor 143 when multi-beam processable area 114 is in the second position and the generated correction value, the morphological information about the multi-beam processable portion of the sample surface when multi-beam processable area 114 is in the first position is determined.

[0134] In step S7, the position and / or orientation (eg, height and / or tilt) of the sample 208 is adjusted using the topography information obtained in step S6.

[0135] In step S8, after the adjustment in step S7, the sample is processed (eg, evaluated, such as inspected or measured) using the multi-beam while the multi-beam processable area 114 is in the second position.

[0136] In some embodiments, Fig. 20As shown, the plurality of sensors include one or more additional sensors 144, 145, such as a fourth proximal sensor 144 and a fifth proximal sensor 145. (Note that the fifth proximal sensor 145 is not the calibration sensor 141 (or the first sensor), which may be referred to as the "fifth sensor" in addition to the four proximal sensors 120A-120D or 142 to 145.) The one or more additional sensors are each positioned so that in a projection of the positions of the sensors 141-145 and the multi-beam processable area 114 on a plane parallel to the sample 208, vectors 155, 156 (or proximal vectors or third and fourth proximal vectors) connecting the positions of the additional sensors 144, 145 to the center of the multi-beam processable area 114 are substantially equal to or opposite to the proximal vector 152 (or the first proximal vector) connecting the position of the third sensor 143 to the center of the multi-beam processable area 114 or the vector 154 (or the second proximal vector) connecting the second sensor 142 to the center of the multi-beam processable area 114. The first proximal vector to the fourth proximal vector all have the same length but different directions. The fourth proximal vector 156 may have an opposite direction to the first proximal vector 152. The third proximal vector 155 may have an opposite direction to the second proximal vector 154. The first proximal vector to the fourth proximal vector may have the same length as any of the distal vectors 151, 153, such as the first distal vector 151 and the second distal vector 153. The first distal vector 151 may connect the first sensor 141 with the second sensor 142. The second distal vector 153 may connect the first sensor 141 with the third sensor 143. The first distal vector 151 may be a translation of the first proximal vector 152, having a common direction and length. The second distal vector 151 may be a translation of the second proximal vector 154, having a common direction and length. These geometric relationships provide enhanced flexibility for obtaining correction factors that can be used to obtain information about the sample surface at the center of the multi-beam processable region 114 using different combinations of sensors 141-145, such as five of four proximal sensors and at least one distal sensor. For example, correction values ​​generated based on the first sensor 141 and the second sensor 142 can be used to obtain information about the sample surface at the center of the multi-beam processable region 114 using the output from the additional sensor 144. Correction values ​​generated based on the first sensor 141 and the third sensor 143 (corresponding to vector 153, such as the second distal vector) can be used to obtain information about the sample surface at the center of the multi-beam processable region 114 using the output from the second sensor 142 or the additional sensor 145 (because vectors 154 and 155 (e.g., the second proximal vector and the third proximal vector) are equal to or opposite to vector 153 (e.g., the second distal vector)).

[0137] Therefore, relative to Fig.19 and Fig. 20 The mirror symmetry of the horizontal and vertical axes in the plane of the page of the illustrated arrangement provides advantages. However, mirror symmetry is not required. The sensors 141-145 are arranged so that only a single vector 151 between two sensors is equal to or opposite to the vector connecting the sensor (optionally, a different sensor) to the center of the multi-beam processable area 114. This arrangement provides the ability to obtain a correction factor that can be used by the (optionally different) sensor to obtain information about the sample surface at the center of the multi-beam processable area 114.

[0138] In some embodiments, Fig.19 and Fig. 20 As illustrated in FIG. 1 , the plurality of sensors 141 -145 include two additional sensors 144 , 145 positioned such that in a projection of the positions of the sensors 141 -145 and the multi-beam processable region 114 onto a plane parallel to the sample 208 , the second sensor 142 , the third sensor 143 and the two additional sensors 144 , 145 define vertices of a rectangle. Fig.19 and Fig. 20 As shown, the first sensor 141 may optionally be aligned with the center of the rectangle in a direction parallel to the first side of the rectangle. Fig.19 and Fig. 20 As shown, the first sensor 141, the second sensor 142, the third sensor 143 and the center of the multi-beam processable area 114 can define the vertices of a rhombus or even a parallelogram. The first sensor 141 can be positioned farther away from the path of the beamlets than the second sensor 142 and the third sensor 143. The distance between the first sensor 141 and the second sensor 142 can be substantially equal to the distance between the first sensor 141 and the third sensor 143.

[0139] In one embodiment, a vector 152 connecting the location of the second sensor 142 and the center of the multi-beam processable area 114 is substantially equal to a vector 153 connecting the location of the third sensor 143 and the first sensor 141 or to the vector 153. Thus, the distance between the first sensor 141 and the third sensor 143 can be substantially the same as the distance between the third sensor 143 and the center of the multi-beam path.

[0140] The plurality of sensors 141-145 may include proximal sensors 120A-120D and distal sensors 121-124, which are arranged as described above with reference to Figure 10-Figure 17For example, a proximal sensor and a distal sensor may be provided such that at least one distal sensor 121 is positioned such that, in a projection of the positions of the sensor and the multi-beam processable region 114 onto a plane parallel to the sample 208, a vector connecting the position of the distal sensor 121 to the position of one of the proximal sensors 120 is substantially equal to or opposite to a vector connecting the position of one of the proximal sensors 120 to the center of the multi-beam processable region 114. Thus, in this case, the distal sensor 121 corresponds to Fig.19 and Fig. 20 The first sensor 141 in the proximal end sensor 120 corresponds to Fig.19 and Fig. 20 Similarly, at least one distal sensor 121 may be positioned such that the distal sensor 121 and the two proximal sensors 120 are configured to measure corresponding portions of the sample surface that together with the center of the multi-beam treatment area 114 define vertices of a rhombus or even a parallelogram. In one embodiment, the plurality of sensors 141-145 are configured such that the first sensor 141 is a distal sensor and the second sensor 142, the third sensor 143, the fourth sensor 144 and the fifth sensor 145 are proximal sensors. In one embodiment, one or more additional sensors are provided and configured to operate as distal sensors. Each of the additional sensors may be positioned at a position corresponding to a distal sensor. Fig.12 At the corresponding distal sensor in the position of the distal sensors 122, 123 and 124 shown in . Each distal sensor can have two nearest proximal sensors. The position of the distal sensor and the distance between each of the two nearest proximal sensors can be the same for each distal sensor.

[0141] The electron optical device described herein can take the form of a series of hole arrays or electron optical elements, which are arranged in an array along a beam or multi-beam path. Such electron optical elements can be electrostatic. In one embodiment, all electron optical elements, such as the last electron optical element in the beam path before the beam limiting hole array to the sample, can be electrostatic and / or can be in the form of a hole array or a plate array. In some arrangements, one or more electron optical elements are manufactured as a microelectromechanical system (MEMS) (i.e., using MEMS manufacturing technology). The electron optical element can have magnetic elements and electrostatic elements. For example, a composite array lens can be characterized by a macroscopic magnetic lens surrounding a multi-beam path, wherein the upper pole plate and the lower pole plate are arranged in the magnetic lens and along the multi-beam path. In the pole plate can be an array of holes for the beam path of the multi-beam. Electrodes can be present above, below, or between the pole plates to control and optimize the electromagnetic field of the composite lens array.

[0142] Evaluation devices, tools or systems according to the present disclosure may include devices for qualitatively evaluating a sample (e.g., pass / fail), devices for quantitatively measuring a sample (e.g., the size of a feature), such as devices for measuring at least a portion of a feature of a sample, or devices 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 metrology tools, or tools capable of performing any combination of evaluation functions associated with inspection tools, review tools, or metrology tools (e.g., subway inspection tools).

[0143] The functions provided by the controller or control system or control unit can be computer-implemented. Any suitable combination of elements can be used to provide the required functions, including, for example, CPU, RAM, SSD, motherboard, network connection, firmware, software and / or other elements known in the art that allow the required computing operations to be performed. The required computing operations can be defined by one or more computer programs. One or more computer programs can be provided in the form of a medium (optionally, a non-temporary medium) storing computer-readable instructions. When the computer-readable instructions are read by the computer, the computer performs the required method steps. The computer may include a self-contained unit or a distributed computing system with multiple different computers connected to each other via a network.

[0144] Various aspects of the invention are disclosed in the following clauses:

[0145] Item 1. An electron optical apparatus, comprising: a stage configured to support a sample having a sample surface; a charged particle device configured to project multiple beams toward the sample along a multi-beam path that intersects the sample in an area that can be processed by multiple beams, the multiple beams comprising multiple sub-beams of charged particles having paths that are desired to be arranged in a grid within the multi-beam path; a sensing system comprising: a set of proximal sensors positioned close to the paths of the multiple sub-beams, each proximal sensor configured to measure a position of a corresponding portion of the sample surface relative to the proximal sensor, and one or more distal sensors, the distal sensor or each distal sensor being further away from the path of the sub-beam than the proximal sensor, the The remote sensor or each remote sensor is configured to measure the position of a corresponding portion of the sample surface relative to the remote sensor; and a control system is configured to: control the charged particle device to use the multiple beams to process the sample surface in the multiple beam processable area, and desirably, to evaluate the sample surface using the multiple beams; control the stage to move the multiple beam processable area along a processing path in the reference frame of the sample; and before the multiple beam processable area reaches a selected portion of the processing path, control the sensing system to use at least the one or more remote sensors to obtain morphological information about the sample surface in the selected portion of the processing path.

[0146] Item 2. An apparatus according to Item 1, wherein the control system is configured to control the sensing system and the charged particle device to respectively obtain topographic information and simultaneously process the sample surface in different corresponding parts of the processing path.

[0147] Item 3. An apparatus according to Item 1 or 2, wherein the control system is configured to adjust the position and / or orientation of the sample based on morphological information about the sample surface obtained in the selected portion when the multi-beam processable area reaches the selected portion.

[0148] Clause 4. The apparatus of any preceding clause, wherein the one or more distal sensors include at least one distal sensor positioned along the treatment path prior to the multi-beam processable region.

[0149] Item 5. An apparatus according to any of the preceding items, wherein the processing path includes multiple routes that are parallel and offset from each other in an offset direction passing through the sample surface, and the control system is configured to move the multi-beam processable area along the routes in sequence, and the control system is desirably configured to shift the multi-beam processable area and the routes relative to each other between different routes of the processing path, desirably shifting in the offset direction passing through the sample surface.

[0150] Item 6. An apparatus according to Item 5, wherein the one or more distal sensors include at least one distal sensor positioned to measure a portion of the sample surface in the same route as the multi-beam processable area, and the at least one distal sensor desirably includes a forward sensor positioned to measure the portion of the sample surface in the same route before the multi-beam processable area moves to the portion of the sample surface.

[0151] Clause 7. The apparatus of clause 6, wherein the at least one distal sensor comprises a distal sensor positioned substantially centrally of the multi-beam processable area along a dimension of the multi-beam processable area perpendicular to the relative movement of the route.

[0152] Clause 8. An apparatus according to clause 6 or 7, wherein the at least one distal sensor includes a rearward sensor and a forward sensor, and the rearward sensor and the forward sensor are positioned to be able to simultaneously measure portions of the sample surface on opposite sides of the multi-beam processable area.

[0153] Clause 9. An apparatus according to any one of clauses 5 to 8, wherein the one or more distal sensors include a side sensor positioned to measure the portion of the sample surface in one of the routes before the multi-beam processable area moves over a portion of the sample surface and when the multi-beam processable area is located within a different one of the routes.

[0154] Item 10. An apparatus according to Item 9, wherein the side sensor is positioned to measure a portion of the sample surface that is substantially aligned with the center of the multi-beam processable area in a direction perpendicular to the relative movement of the multi-beam processable area along one of the routes.

[0155] Clause 11. An apparatus according to clause 9 or 10, wherein the side sensor is a first side sensor, and the one or more distal sensors further include a second side sensor, wherein the first side sensor and the second side sensor are positioned to be able to simultaneously measure portions of the sample surface on opposite sides of the multi-beam processable area, desirably, within a route different from the route in which the multi-beam processable area is currently located.

[0156] Clause 12. The apparatus of any preceding clause, wherein the set of proximal sensors comprises four proximal sensors positioned to measure four respective portions of the sample surface, the four respective portions defining vertices of a four-sided shape.

[0157] Clause 13. The device of clause 12, wherein the four-sided shape is a rectangle.

[0158] Clause 14. The device of clause 13, wherein the one or more distal sensors include a first distal sensor positioned to measure a corresponding portion of the sample surface, the corresponding portion aligned with a center of the rectangle in a direction parallel to a first side of the rectangle.

[0159] Clause 15. An apparatus according to clause 14, wherein the one or more distal sensors also include a second distal sensor positioned to measure a portion of the sample surface, the portion being aligned with the center of the rectangle in a direction parallel to a second side of the rectangle, the second side being orthogonal to the first side.

[0160] Clause 16. An apparatus according to any one of clauses 12 to 15, wherein the one or more distal sensors include at least one distal sensor, and the at least one distal sensor is positioned so that the distal sensor and two of the proximal sensors are configured to measure corresponding portions of the sample surface, and the corresponding portions together with the center of the multi-beam processing area define the vertices of the rhombus.

[0161] Clause 17. An apparatus according to any of the preceding clauses, wherein the one or more distal sensors include at least one distal sensor, and the at least one distal sensor is positioned so that in a projection of the positions of the sensor and the multi-beam processable area onto a plane parallel to the sample, a vector connecting the position of the distal sensor to the position of one of the proximal sensors is substantially equal to or opposite to a vector connecting the position of one of the proximal sensors to the center of the multi-beam processable area.

[0162] Clause 18. The apparatus of any preceding clause, wherein the proximal sensor and the one or more distal sensors are positioned at substantially the same distance from the stage.

[0163] Item 19. An electron optical device comprising: a stage configured to support a sample having a sample surface; a charged particle device configured to project multiple beams toward the sample along a multi-beam path intersecting the sample in a multi-beam processable region to process the sample with the multiple beams, the multiple beams comprising multiple sub-beams of charged particles having paths that are desired to be arranged in a grid within the multi-beam path; and a sensing system comprising a plurality of sensors, each sensor being configured to measure a position of a corresponding portion of the sample surface relative to the sensor outside the multi-beam processable region, wherein the plurality of sensors include at least a first sensor, a second sensor, and a third sensor, the first sensor, the second sensor, and the third sensor being positioned so that in a projection of the positions of the sensors and the multi-beam processable region onto a plane parallel to the sample, a vector connecting the positions of the first sensor and the second sensor is substantially equal to or opposite to a vector connecting the position of the third sensor to the center of the multi-beam processable region.

[0164] Item 20. The apparatus according to Item 19 further includes a control system configured to determine morphological information about a portion of the sample surface to be processed by the multi-beam by: controlling the stage so that the multi-beam processable area is located at a first position on the sample surface; when the multi-beam processable area is located at the first position, controlling the sensing system to obtain measurement results of the sample surface using the first sensor and the second sensor; generating a correction value using the measurement results obtained by the first sensor and the second sensor when the multi-beam processable area is located at the first position; and controlling the stage so that the multi-beam processable area moves to the sample. a second position on a surface, wherein the second position desirably positions the third sensor to measure a portion of the sample surface that is substantially the same as the portion that the first sensor is positioned to measure when the multi-beam processable area is in the first position; controlling the sensing system to obtain measurements of the sample surface using the third sensor when the multi-beam processable area is in the second position; and determining topographic information about a portion of the sample surface that is processable by the multi-beam processable area when the multi-beam processable area is in the second position by using the measurements obtained by the third sensor when the multi-beam processable area is in the second position and the correction value generated.

[0165] Item 21. An apparatus according to item 19 or 20, wherein the multiple sensors include one or more additional sensors, each additional sensor being positioned so that in a projection of the positions of the sensor and the multi-beam processable area onto a plane parallel to the sample, a vector connecting the position of the additional sensor to the center of the multi-beam path is substantially equal to or opposite to: a vector connecting the position of the third sensor to the center of the multi-beam path; or a vector connecting either the first sensor or the second sensor to the center of the multi-beam processable area.

[0166] Item 22. An apparatus according to any one of items 19 to 21, wherein the plurality of sensors includes two additional sensors, and the two additional sensors are positioned so that in a projection of the positions of the sensors and the multi-beam processable area onto a plane parallel to the sample, the second sensor, the third sensor and the two additional sensors define vertices of a rectangle.

[0167] Item 23. An apparatus according to Item 22, wherein in a projection of the positions of the sensor and the multi-beam processable area onto a plane parallel to the sample, the first sensor is aligned with the center of the rectangle in a direction parallel to the first side of the rectangle.

[0168] Item 24. An apparatus according to any one of items 19 to 23, wherein in a projection of the positions of the sensors and the multi-beam processable area onto a plane parallel to the sample, the first sensor, the second sensor, the third sensor and the center of the multi-beam processable area define vertices of a rhombus.

[0169] Clause 25. Apparatus according to any one of clauses 19 to 24, wherein the first sensor is further from the path of the beamlet than the second sensor and the third sensor.

[0170] Clause 26. The apparatus of any one of clauses 19 to 25, wherein a distance between the first sensor and the second sensor is substantially equal to a distance between the first sensor and the third sensor.

[0171] Item 27. An apparatus according to any one of items 19 to 26, wherein in a projection of the positions of the sensors and the multi-beam processable area onto a plane parallel to the sample, the vector connecting the position of the second sensor and the center of the multi-beam processable area is substantially equal to or opposite to the vector connecting the position of the third sensor and the first sensor.

[0172] Clause 28. The apparatus of any one of clauses 19 to 27, wherein a distance between the first sensor and the third sensor is substantially equal to a distance between the third sensor and the center of the multi-beam path.

[0173] Clause 29. An apparatus according to any one of clauses 19 to 28, wherein the second sensor and the third sensor and, preferably, at least one of the additional sensors in the case of the additional sensor being provided are proximal sensors, and the first sensor and, preferably, at least one further sensor are distal sensors, preferably, the first sensor is a calibrated sensor, preferably, each distal sensor has two nearest proximal sensors and the position of the distal sensor is the same distance between each of the two nearest proximal sensors.

[0174] Clause 30. The apparatus of Clause 1, wherein the one or more remote sensors include at least one remote sensor positioned away from the grid along the processing path.

[0175] Clause 31. An apparatus according to clause 1 or 30, wherein the one or more distal sensors include a side sensor, which is positioned away from the grid in a direction orthogonal to the processing path, desirably positioned on a different side of the grid than a forward sensor or a rearward sensor.

[0176] Clause 32. The apparatus of clause 1, 30, or 31, wherein the side sensor is a first side sensor, and the one or more distal sensors further comprise a second side sensor located on a side of the grid opposite the first side sensor.

[0177] Clause 33. An apparatus according to any one of clauses 1 and 30 to 32, wherein the at least one or each distal sensor is positioned substantially centrally relative to a dimension of the grid near the sample surface orthogonal to the multiple beam paths.

[0178] Item 34. An apparatus according to any one of items 1 and 30 to 33, wherein the control system is configured to shift the sample and the grid relative to each other between different routes of the processing path through the sample surface, desirably, the routes are parallel and offset relative to each other, desirably, the control system is configured to move the sample and the grid sequentially relative to each other between the routes.

[0179] Clause 35. The device of clause 34, wherein the one or more remote sensors include at least one remote sensor positioned relative to the grid and the processing path to measure a portion of the sample surface in the same lane.

[0180] Clause 36. The apparatus of clause 35, wherein the at least one distal sensor comprises at least one of a forward sensor and a backward sensor configured to measure a portion of the sample surface displaced from the grid along the route.

[0181] Clause 37. Apparatus according to any one of clauses 34 to 36 as appended to clause 31, wherein the side sensor is positioned to measure a portion of the sample surface in a different route to the route in the multi-beam path.

[0182] Clause 38. An apparatus according to clause 37, wherein the side sensor is positioned to measure a portion of the sample surface that is displaced along a route different from the route in the multi-beam path in a direction perpendicular to the relative movement between the sample surface and the grid.

[0183] Clause 39. An apparatus according to any one of clauses 1 to 18 and 30 to 38, wherein the set of proximal sensors includes four proximal sensors, and the four proximal sensors are positioned so that the four proximal sensors define corresponding vertices of a quadrilateral centered on the center of the multi-beam, and the quadrilateral is desirably a rectangle.

[0184] Clause 40. An apparatus according to any one of clauses 1 to 18 and 30 to 39, wherein the apparatus is configured to use the acquired topographic information to dynamically position the sample and / or adjust the position and / or orientation of the stage when the multi-beam volume reaches the selected portion of the processing path.

[0185] Clause 41. A method for obtaining topographic information about a sample surface, comprising: projecting multiple beams of charged particles toward the sample along a multiple beam path intersecting the sample in a region processable by multiple beams to process the sample surface in the region processable by multiple beams, the multiple beams comprising multiple beamlets having paths desirably arranged in a grid within the multiple beam path; using a set of proximal sensors positioned proximate to the paths of the multiple beamlets to measure positions of corresponding portions of the sample surface relative to the proximal sensors;

[0186] using one or more distal sensors further from the path of the beamlets than the proximal sensors to measure one or more respective portions of the sample surface relative to the one or more distal sensors;

[0187] providing relative movement between the multi-beam processable region and the sample such that the multi-beam processable region moves along a processing path in a reference frame of the sample; and

[0188] At least the one or more distal sensors are used to obtain topographic information about the sample surface in the selected portion of the processing path before the multi-beam processable region reaches the selected portion of the processing path.

[0189] Clause 42. The method of clause 41, comprising obtaining topographic information in a portion of the processing path while processing the sample surface using the multiple beams in another portion of the processing path.

[0190] Item 43. The method according to Item 41 or 42 also includes controlling the position and / or orientation of the sample based on morphological information about the sample surface obtained in the selected portion of the processing path when the multi-beam processable area reaches the selected portion of the processing path.

[0191] Clause 44. The method of any one of clauses 41 to 43, wherein the one or more distal sensors include at least one distal sensor positioned along the treatment path prior to the multi-beam processable region.

[0192] Item 45. A method according to item 44, wherein the processing path includes multiple routes, the multiple routes are parallel and offset from each other in an offset direction passing through the sample surface, and the providing relative movement includes sequentially moving the multi-beam processable area along the routes, desirably causing the multi-beam processable area and the routes to shift relative to each other between different routes of the processing path, desirably shifting in the offset direction passing through the sample surface.

[0193] Clause 46. A method according to any one of clauses 41 to 45, wherein the one or more remote sensors include at least one remote sensor that measures a portion of the sample surface in the same route as the multi-beam processable area, desirably serving as a forward sensor that measures the portion of the sample surface in the same route before the multi-beam processable area moves over the portion of the sample surface.

[0194] Clause 47. The method of clause 46, wherein the at least one distal sensor comprises a distal sensor positioned substantially centrally relative to a size of the multi-beam processable area perpendicular to relative movement of the multi-beam processable area along the route.

[0195] Clause 48. A method according to clause 46 or 47, wherein the at least one distal sensor includes a rearward sensor and a forward sensor, and the rearward sensor and the forward sensor are used to simultaneously measure portions of the sample surface on opposite sides of the multi-beam processable area.

[0196] Clause 49. A method according to any one of clauses 45 to 48, wherein the one or more distal sensors include a side sensor that measures the portion of the sample surface in one of the routes before the multi-beam processable area moves over the portion of the sample surface and when the multi-beam processable area is located within a different route in the route.

[0197] Clause 50. A method according to clause 49, wherein the side sensor measures a portion of the sample surface that is substantially aligned with the center of the multi-beam processable area in a direction perpendicular to the relative movement of the multi-beam processable area along one of the routes.

[0198] Item 51. A method according to Item 50, wherein the side sensor is a first side sensor, and the one or more distal sensors further include a second side sensor, wherein the first side sensor and the second side sensor are capable of simultaneously measuring a portion of the sample surface on opposite sides of the multi-beam processable area, desirably, within a route different from the route in which the multi-beam processable area is currently located.

[0199] Clause 52. The method of any one of Clauses 41 to 51, wherein the set of proximal sensors comprises four proximal sensors positioned to measure four respective portions of the sample surface, the four respective portions defining vertices of a four-sided shape.

[0200] Clause 53. The method of Clause 52, wherein the four-sided shape is a rectangle.

[0201] Clause 54. The method of clause 53, wherein the one or more distal sensors include a first distal sensor that measures a corresponding portion of the sample surface, the corresponding portion being aligned with a center of the rectangle in a direction parallel to a first side of the rectangle.

[0202] Clause 55. A method according to clause 54, wherein the one or more remote sensors also include a second remote sensor that measures a portion of the sample surface, the portion being aligned with the center of the rectangle in a direction parallel to a second side of the rectangle, the second side being orthogonal to the first side.

[0203] Clause 56. A method according to any one of clauses 52 to 55, wherein the one or more distal sensors include at least one distal sensor, and the at least one distal sensor is positioned so that the distal sensor and two of the proximal sensors measure corresponding portions of the sample surface, and the corresponding portions together with the center of the multi-beam processable area define the vertices of a rhombus.

[0204] Clause 57. A method according to any one of clauses 42 to 56, wherein the one or more distal sensors include at least one distal sensor, and the at least one distal sensor is positioned so that in a projection of the positions of the sensor and the multi-beam processable area onto a plane parallel to the sample, a vector connecting the position of the distal sensor to the position of one of the proximal sensors is substantially equal to or opposite to a vector connecting the position of one of the proximal sensors to the center of the multi-beam processable area.

[0205] Clause 58. The method of any one of clauses 42 to 57, wherein the proximal sensor and the one or more distal sensors are positioned at substantially the same distance from the stage.

[0206] Item 59. A method for obtaining morphological information about a sample surface, comprising: projecting multiple beams of charged particles toward the sample along a multi-beam path that intersects the sample in a region that can be processed by multiple beams to process the sample with the multiple beams, the multiple beams including multiple sub-beams having paths that are expected to be arranged in a grid within the multi-beam path; using multiple sensors to measure positions of corresponding portions of the sample surface relative to the sensors outside the region that can be processed by multiple beams, thereby obtaining morphological information about the sample surface, wherein the multiple sensors include at least a first sensor, a second sensor, and a third sensor, the first sensor, the second sensor, and the third sensor being positioned so that in a projection of the positions of the sensors and the region that can be processed by multiple beams onto a plane parallel to the sample, a vector connecting the positions of the first sensor and the second sensor is substantially equal to or opposite to a vector connecting the position of the third sensor to the center of the region that can be processed by multiple beams.

[0207] Item 60. A method according to Item 59, wherein obtaining morphological information includes: positioning the multi-beam processable area at a first position on the sample surface; obtaining measurements of the sample surface using the first sensor and the second sensor when the multi-beam processable area is at the first position; generating correction values ​​using the measurements obtained by the first sensor and the second sensor when the multi-beam processable area is at the first position; moving the multi-beam processable area to a second position on the sample surface, the second position desirably causing the third sensor to be positioned to measure a portion of the sample surface that is substantially the same as the portion that the first sensor was positioned to measure when the multi-beam processable area was at the first position; obtaining measurements of the sample surface using the third sensor when the multi-beam processable area is at the second position; and determining morphological information about a portion of the sample surface that is processable by the multi-beam processable area when the multi-beam processable area is at the second position by using the measurements obtained by the third sensor when the multi-beam processable area is at the second position and the correction values ​​generated.

[0208] Item 61. A method according to item 59 or 60, wherein the multiple sensors include one or more additional sensors, each additional sensor is positioned so that in the projection of the positions of the sensor and the multi-beam processable area onto a plane parallel to the sample, the vector connecting the position of the additional sensor to the center of the multi-beam processable area is substantially equal to or opposite to: the vector connecting the position of the third sensor to the center of the multi-beam processable area; or the vector connecting either the first sensor or the second sensor to the center of the multi-beam path.

[0209] Item 62. A method according to any one of items 59 to 61, wherein the plurality of sensors includes two additional sensors, and the two additional sensors are positioned so that in a projection of the positions of the sensors and the multi-beam processable area onto a plane parallel to the sample, the second sensor, the third sensor and the two additional sensors define vertices of a rectangle.

[0210] Item 63. A method according to Item 62, wherein in a projection of the positions of the sensor and the multi-beam processable area onto a plane parallel to the sample, the first sensor is aligned with the center of the rectangle in a direction parallel to the first side of the rectangle.

[0211] Item 64. A method according to any one of items 59 to 63, wherein in the projection of the positions of the sensors and the multi-beam processable area onto a plane parallel to the sample, the first sensor, the second sensor, the third sensor and the center of the multi-beam processable area define vertices of a rhombus.

[0212] Clause 65. The method of any one of clauses 59 to 64, wherein the first sensor is positioned further from the path of the beamlet than the second sensor and the third sensor.

[0213] Clause 66. The method of any one of clauses 59 to 65, wherein a distance between the first sensor and the second sensor is substantially equal to a distance between the first sensor and the third sensor.

[0214] Clause 67. A computer program comprising instructions interpretable by a computer controlling an evaluation device, the computer program comprising instructions for performing a method according to any one of clauses 41 to 66.

[0215] Although the present invention has been described in conjunction with various embodiments, other embodiments of the present invention will be apparent to those skilled in the art through consideration of the specification and practice of the invention disclosed herein. The specification and embodiments are to be considered exemplary only, with the true scope and spirit of the present invention being indicated by the appended claims.

Claims

1. A method for obtaining topographic information about a sample surface, comprising: Projecting a plurality of beams of charged particles toward a sample along a multi-beam path that intersects the sample in a multi-beam processable region to process a surface of the sample in the multi-beam processable region, the multi-beam comprising a plurality of beamlets having paths within the multi-beam path that are desirably arranged in a grid; measuring positions of respective portions of the sample surface relative to the proximal sensors using a set of proximal sensors positioned proximate the paths of the plurality of beamlets; using one or more distal sensors positioned further from the path of the beamlets than the proximal sensors to measure one or more respective portions of the sample surface relative to the one or more distal sensors; providing relative movement between the multi-beam processable region and the sample such that the multi-beam processable region moves along a processing path in a reference frame of the sample; as well as The at least one or more remote sensors are used to obtain topographic information about the sample surface in the selected portion of the processing path before the multi-beam processable region reaches the selected portion of the processing path.

2. The method of claim 1 , comprising obtaining topographic information in one portion of the processing path while simultaneously processing the sample surface using the multiple beams in another portion of the processing path.

3. The method according to claim 1 or 2 also includes controlling the position and / or orientation of the sample based on the morphological information about the sample surface obtained in the selected part of the processing path when the multi-beam processable area reaches the selected part.

4. A method according to any one of claims 1 to 3, wherein the one or more distal sensors include at least one distal sensor positioned along the processing path before the multi-beam processable area, preferably wherein the processing path includes multiple routes, the multiple routes are parallel and offset relative to each other in an offset direction across the sample surface, and providing relative movement includes moving the multi-beam processable area sequentially along the routes, preferably between different routes of the processing path, preferably causing the multi-beam processable area and the routes to shift relative to each other in the offset direction across the sample surface.

5. A method according to any one of claims 1 to 4, wherein the one or more distal sensors include at least one distal sensor that measures a portion of the sample surface in the same route as the multi-beam processable area, desirably serving as a forward sensor that measures the portion of the sample surface in the same route before the multi-beam processable area moves over the portion of the sample surface.

6. The method of claim 5, wherein the at least one distal sensor comprises a distal sensor positioned substantially centrally relative to a size of the multi-beam processable area perpendicular to relative movement of the multi-beam processable area along the route.

7. The method of claim 5 or 6, wherein the at least one distal sensor comprises a rearward sensor and the forward sensor, the rearward sensor and the forward sensor being used to simultaneously measure portions of the sample surface on opposite sides of the multi-beam processable area.

8. A method according to any one of claims 5 to 7, wherein the one or more distal sensors include a side sensor, which measures a portion of the sample surface in one of the routes before the multi-beam processable area moves over the portion of the sample surface and when the multi-beam processable area is located within a different route in the route.

9. The method of any one of claims 1 to 8, wherein the set of proximal sensors comprises four proximal sensors positioned to measure four corresponding portions of the sample surface defining vertices of a quadrilateral shape.

10. The method of claim 9, wherein the four-sided shape is a rectangle and the one or more distal sensors include a first distal sensor that measures a corresponding portion of the sample surface aligned with a center of the rectangle in a direction parallel to a first side of the rectangle.

11. The method of claim 10, wherein the one or more distal sensors further comprises a second distal sensor that measures a portion of the sample surface aligned with the center of the rectangle in a direction parallel to a second side of the rectangle, the second side being orthogonal to the first side.

12. A method according to any one of claims 9 to 11, wherein the one or more distal sensors include at least one distal sensor, and the at least one distal sensor is positioned so that the distal sensor and two of the proximal sensors measure corresponding portions of the sample surface, and the corresponding portions together with the center of the multi-beam processable area define the vertices of a rhombus.

13. The method according to any one of claims 2 to 12, wherein the one or more distal sensors include at least one distal sensor, and the at least one distal sensor is positioned so that in a projection of the positions of the sensor and the multi-beam processable area on a plane parallel to the sample, a vector connecting the position of the distal sensor with the position of one of the proximal sensors is substantially equal to or opposite to a vector connecting the position of one of the proximal sensors with the center of the multi-beam processable area.

14. A method according to any one of claims 2 to 13, wherein the proximal sensor and the one or more distal sensors are positioned at substantially the same distance from the stage.

15. An electro-optical device comprising: a stage configured to support a sample having a sample surface; a charged particle device configured to project a multi-beam toward the sample along a multi-beam path intersecting the sample in a multi-beam processable region, the multi-beam comprising a plurality of charged particle beamlets having paths desirably arranged in a grid within the multi-beam path; Sensing system, including: a set of proximal sensors positioned proximate to the paths of the plurality of beamlets, each proximal sensor configured to measure a position of a corresponding portion of the sample surface relative to the proximal sensor, and one or more distal sensors, the or each distal sensor being positioned further from the path of the beamlet than the proximal sensor, the or each distal sensor being configured to measure a position of a respective portion of the sample surface relative to the distal sensor; and The control system is configured as: controlling the charged particle device to process the sample surface in the multi-beam processable region using the multiple beams, desirably evaluating the sample surface using the multiple beams; controlling the stage to move the multi-beam processable region along a processing path in a reference frame of the sample; and The sensing system is controlled to use at least the one or more remote sensors to obtain topographic information about the sample surface in the selected portion of the processing path before the multi-beam processable region reaches the selected portion of the processing path.

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