Charged particle assessment tool, inspection method

Abstract

A charged particle evaluation tool includes: an objective lens configured to project a plurality of charged particle beams onto a sample, the objective lens having a sample-facing surface defining a plurality of beam apertures through which a respective charged particle beam is emitted toward the sample; and a plurality of trapping electrodes adjacent to the respective beam apertures and configured to trap the charged particles emitted from the sample.

Description

[0001] Cross-reference of related applications

[0002] This application claims priority to EP application 20150394.3, filed on January 6, 2020, EP application 20184160.8, filed on July 6, 2020, and EP application 20198201.4, filed on September 24, 2020, which are each incorporated herein by reference in their entirety. Technical Field

[0003] The embodiments provided herein generally relate to charged particle evaluation tools and inspection methods, and more particularly to charged particle evaluation tools and inspection methods using multiple sub-beams of charged particles. Background Technology

[0004] When manufacturing semiconductor integrated circuit (IC) chips, undesirable pattern defects inevitably occur on the substrate (i.e., wafer) or mask during the manufacturing process, as a result of optical effects and incident particles, thereby reducing yield. Therefore, monitoring the extent of these undesirable pattern defects is a crucial process in IC chip manufacturing. More generally, the inspection and / or measurement of the surface of the substrate or other objects / materials is an important process during and / or after its manufacturing.

[0005] Pattern inspection tools with charged particle beams have been used to inspect objects, for example, to detect pattern defects. These tools typically employ electron microscopy techniques, such as scanning electron microscopy (SEM). In SEM, a primary electron beam of electrons at relatively high energies targets a final deceleration step so that it falls onto the sample at a relatively low landing energy. The electron beam is focused onto the sample as a probe spot. The interaction between the material structure at the probe spot and the landing electrons from the electron beam causes electrons to be emitted from the surface, such as secondary electrons, backscattered electrons, or Auger electrons. The generated secondary electrons can be emitted from the material structure of the sample. By scanning the primary electron beam, which acts as a probe spot, across the sample surface, secondary electrons can be emitted across the sample surface. By collecting these emitted secondary electrons from the sample surface, the pattern inspection tool can obtain an image representing the characteristics of the material structure of the sample surface.

[0006] It is often necessary to improve the throughput and other characteristics of charged particle inspection tools. Summary of the Invention

[0007] The purpose of this disclosure is to provide embodiments that support improvements in the throughput or other characteristics of charged particle evaluation tools.

[0008] According to a first aspect of the present invention, a charged particle evaluation tool is provided, comprising:

[0009] An objective lens, configured to project multiple beams of charged particles onto a sample, defines multiple beam apertures through which corresponding charged particle beams can propagate toward the sample; and

[0010] Multiple sensor units, adjacent to corresponding beam apertures in the beam aperture, are configured to capture charged particles emitted from the sample.

[0011] According to a second aspect of the present invention, a method for manufacturing an evaluation tool is provided, the method comprising:

[0012] Multiple sensor units are formed on a substrate, and multiple apertures are formed in the substrate; and

[0013] A substrate is attached to an objective lens configured to project multiple beams of charged particles onto the sample, such that the beams of charged particles can be emitted through an aperture.

[0014] According to a third aspect of the present invention, an inspection method is provided, comprising:

[0015] Multiple charged particle beams are emitted radially from the sample through multiple beam apertures; and

[0016] Multiple sensor units are used, positioned adjacent to the corresponding aperture in the beam aperture, to capture charged particles emitted by the sample in response to the charged particle beam.

[0017] According to a fourth aspect of the present invention, a multi-beam electro-optical system is provided, the multi-beam electro-optical system including a final electro-optical element in a multi-beam path of the multi-beam electro-optical system, the final electro-optical element comprising:

[0018] - A multi-manipulator array, wherein each array element is configured to manipulate at least one electron beam in a multi-beam path; and

[0019] - A detector configured and oriented to detect electrons emitted from a sample located in a multi-beam path, wherein the detector includes multiple sensor units integrated into a multi-manipulator array and at least one sensor unit associated with each array element.

[0020] According to a fourth aspect of the invention, a final electron-optical element is provided for a multi-band charged beam projection system configured to project a plurality of charged particle beams onto a sample, the final electron-optical element comprising:

[0021] An objective lens having a sample-facing surface that defines multiple beam apertures through which corresponding charged particle beams in a charged particle beam can propagate toward the sample; and

[0022] Multiple sensor units, adjacent to corresponding beam apertures in the beam aperture, are configured to capture charged particles emitted from the sample.

[0023] Other advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which certain embodiments of the invention are illustrated by way of description and example. Attached Figure Description

[0024] The above and other aspects of this disclosure will become more apparent from the description of exemplary embodiments in conjunction with the accompanying drawings.

[0025] Figure 1 This is a schematic diagram illustrating an exemplary charged particle beam inspection device.

[0026] Figure 2 It is illustrated as Figure 1 A schematic diagram of an exemplary multi-beam device, representing a portion of an exemplary charged particle beam inspection device.

[0027] Figure 3 It's a diagram. Figure 1 A schematic diagram of an exemplary multi-beam device with an exemplary configuration of the source conversion unit of an exemplary charged particle beam inspection device.

[0028] Figure 4 This is a schematic cross-sectional view of the objective lens of the inspection device according to an embodiment.

[0029] Figure 5 yes Figure 4 Bottom view of the objective lens.

[0030] Figure 6 yes Figure 4 A modified bottom view of the objective lens.

[0031] Figure 7 It is included Figure 4 A magnified schematic cross-sectional view of the detector in the objective lens.

[0032] Figure 8 This is a schematic diagram of a theoretical transimpedance amplifier.

[0033] Figure 9 This is a schematic diagram of a transimpedance amplifier that indicates thermal noise effects.

[0034] Figure 10 It's shown in the diagram. Figure 1 A schematic diagram of another exemplary multi-beam device, which is part of an exemplary charged particle beam inspection device.

[0035] Figure 11 This is a schematic diagram illustrating another exemplary multi-beam device according to an embodiment.

[0036] Figure 12This is a schematic diagram of another exemplary multi-beam device according to an embodiment.

[0037] Figure 13 This is a schematic cross-sectional view of the objective lens of the inspection device according to an embodiment.

[0038] Figure 14 It is included Figure 13 Bottom view of the detector unit in the objective lens.

[0039] Figure 15 This is a schematic diagram illustrating another exemplary multi-beam device according to an embodiment.

[0040] Figure 16 It is included Figure 15 A magnified schematic cross-sectional view of the detector in the objective lens of the device, showing the detector in different positions.

[0041] Figure 17 It is possible Figure 15 A magnified schematic cross-sectional view of the alternative detector used in the objective lens of the device. Detailed Implementation

[0042] 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 the same numbers in different drawings denote the same or similar elements unless otherwise stated. The implementations set forth in the following description of the exemplary embodiments do not represent all implementations consistent with the invention. Rather, they are merely examples of devices and methods consistent with the aspects of the invention relevance described in the appended claims.

[0043] Enhanced computing power (reduced physical size of the device) in electronic devices can be achieved by significantly increasing the packaging density of circuit components (such as transistors, capacitors, diodes, etc.) on an IC chip. This has been achieved through increased resolution, which allows for the fabrication of smaller structures. For example, the IC chip in a smartphone can include more than 2 billion transistors, each smaller than 1 / 1000th the size of a human hair; IC chips the size of a thumbnail were available in 2019 or earlier. Therefore, it is not surprising that semiconductor IC manufacturing is a complex and time-consuming process with hundreds of individual steps. Even an error in one step can significantly affect the functionality of the final product. A single “fatal defect” can cause a device to fail. The goal of a manufacturing process is to improve the overall process yield. For example, for a 50-step process (where one step can indicate the number of layers formed on the wafer), to achieve a 75% yield, each individual step must have a yield greater than 99.4%. If individual steps have a yield of 95%, the overall process yield will be as low as 7%.

[0044] While high process yields are required in IC chip manufacturing facilities, maintaining high substrate (i.e., wafer) throughput (defined as the number of substrates processed per hour) is also important. The presence of defects can impact both high process yields and high substrate throughput. This is especially true in situations requiring operator intervention to inspect for defects. Therefore, high-throughput detection and identification of micron- and nanometer-scale defects using inspection tools such as scanning electron microscopy (“SEM”) is crucial for maintaining both high yields and low costs.

[0045] SEM comprises a scanning device and a detector device. The scanning device includes an illumination device and a projection device. The illumination device includes an electron source for generating primary electrons, and the projection device is used to scan a sample, such as a substrate, using one or more focused beams of primary electrons. At least the illumination device or system and the projection device or system can be collectively referred to as an electron optics system or apparatus. Primary electrons interact with the sample and generate secondary electrons. When scanning the sample, the detector device captures the secondary electrons from the sample, allowing the SEM to create an image of the scanned area of ​​the sample. For high-throughput inspection, some inspection devices use multiple focused beams, i.e., multiple beams of primary electrons. The component beams in a multi-beam inspection can be referred to as sub-beams or split beams. Multi-beam inspection can scan different portions of the sample simultaneously. Therefore, multi-beam inspection devices are able to inspect samples at much higher speeds than single-beam inspection devices.

[0046] In multi-beam inspection equipment, some primary electron beams deviate from the central axis of the scanning device, i.e., the midpoint of the primary electron optical axis. To ensure that all electron beams reach the sample surface at substantially the same incident angle, it is necessary to manipulate sub-beam paths with a greater radial distance from the central axis, shifting them by a larger angle than paths closer to the central axis. This stronger manipulation can introduce aberrations that result in blurred and out-of-focus images of the sample substrate. In particular, for sub-beam paths not on the central axis, the aberrations of the sub-beams can increase with radial displacement from the central axis. When secondary electrons are detected, these aberrations may remain associated with the secondary electrons. Therefore, these aberrations degrade the quality of the image created during inspection.

[0047] The following describes the implementation of a known multi-beam inspection device.

[0048] The accompanying drawings are schematic. Therefore, for clarity, the relative dimensions of the components in the drawings are enlarged. In the following description of the drawings, the same or similar reference numerals refer to the same or similar components or entities, and only differences with respect to various embodiments are described. Although the description and drawings are directed to electro-optical devices, it should be understood that these embodiments are not intended to limit this disclosure to specific charged particles. Therefore, references to electrons in this document can be more generally considered as references to charged particles, where charged particles are not necessarily electrons.

[0049] Now for reference Figure 1 , Figure 1 This is a schematic diagram illustrating an exemplary charged particle beam inspection device 100. Figure 1 The charged particle beam inspection device 100 includes a main chamber 10, a loading and locking chamber 20, an electron beam tool 40, an equipment front-end module (EFEM) 30, and a controller 50. The electron beam tool 40 is located inside the main chamber 10.

[0050] EFEM 30 includes a first loading port 30a and a second loading port 30b. EFEM 30 may include additional loading ports(s). For example, the first loading port 30a and the second loading port 30b may receive a front-opening substrate integration chamber (FOUP) containing a substrate (e.g., a semiconductor substrate or a substrate made of other materials(s)) or a sample to be inspected (substrate, wafer, and sample are collectively referred to below as “sample”). One or more robotic arms (not shown) in EFEM 30 transport the sample to the loading locking chamber 20.

[0051] Loading lock chamber 20 is used to remove gas surrounding the sample. This creates a vacuum where the local gas pressure is lower than the pressure in the surrounding environment. Loading lock chamber 20 can be connected to a loading lock vacuum pump system (not shown), which removes gas particles from loading lock chamber 20. Operation of the loading lock vacuum pump system enables loading lock chamber to reach a first pressure below atmospheric pressure. After reaching the first pressure, one or more robotic arms (not shown) transport the sample from loading lock chamber 20 to main chamber 10. Main chamber 10 is connected to a main chamber vacuum pump system (not shown). The main chamber vacuum pump system removes gas particles from main chamber 10, causing the pressure around the sample to reach a second pressure below the first pressure. After reaching the second pressure, the sample is transported to an electron beam tool through which the sample can be examined. Electron beam tool 40 may include multi-beam electron optics.

[0052] The controller 50 is electrically connected to the electron beam tool 40. The controller 50 may be a processor (such as a computer) configured to control the charged particle beam inspection device 100. The controller 50 may also include a processing circuitry system configured to perform various signal and image processing functions. Although the controller 50 is... Figure 1The controller 50 is shown outside the structure comprising the main chamber 10, the loading and locking chamber 20, and the EFEM 30; however, it should be understood that the controller 50 may be part of this structure. The controller 50 may be located in one of the components of the charged particle beam inspection apparatus, or it may be distributed across at least two of the components. While this disclosure provides an example of a main chamber 10 for housing electron beam inspection tools, it should be noted that aspects of this disclosure are not limited, in their broadest sense, to the chamber housing electron beam inspection tools. Of course, it should be understood that the above principles can also be applied to other arrangements of other tools and apparatuses operating under a second pressure.

[0053] Now for reference Figure 2 , Figure 2 The diagram illustrates the inclusion of... Figure 1 This is a schematic diagram of an exemplary electron beam tool 40, a part of an exemplary charged particle beam inspection apparatus 100. The multi-beam electron beam tool 40 (also referred to herein as apparatus 40) includes an electron source 201, an aperture plate 271, a focusing lens 210, a source conversion unit 220, a primary projection device 230, a motorized stage 209, and a sample holder 207. The electron source 201, aperture plate 271, focusing lens 210, and source conversion unit 220 are components of the irradiation apparatus included in the multi-beam electron beam tool 40. The sample holder 207 is supported by the motorized stage 209 to hold a sample 208 (e.g., a substrate or mask) for inspection. The multi-beam electron beam tool 40 may also include a secondary projection device 250 and an associated electron detection device 240. The primary projection device 230 may include an objective lens 231, such as a single lens that operates on the entire beam. The objective lens can be the final electro-optical element in the path of a multi-beam system or in an electro-optical system; therefore, the objective lens can be referred to as a final electro-optical element. The electronic detection device 240 may include multiple detection elements 241, 242, and 243. The beam splitter 233 and the deflection scanning unit 232 may be located within the primary projection device 230.

[0054] The components used to generate the primary beam can be aligned with the primary electron optical axis of device 40. These components may include: an electron source 201, a bore plate 271, a focusing lens 210, a source conversion unit 220, a beam splitter 233, a deflection scanning unit 232, and a primary projection device 230. The secondary projection device 250 and its associated electronic detection device 240 can be aligned with the secondary electron optical axis 251 of device 40.

[0055] The primary electron optical axis 204 is composed of the electron optical axis of the electron beam tool 40, which is part of the irradiation device. The secondary electron optical axis 251 is the electron optical axis of the electron beam tool 40, which is part of the detection device. The primary electron optical axis 204 may also be referred to herein as the primary optical axis (for ease of reference) or the charged particle optical axis. The secondary electron optical axis 251 may also be referred to herein as the secondary optical axis or the secondary charged particle optical axis.

[0056] The electron source 201 may include a cathode (not shown) and an extractor or anode (not shown). During operation, the electron source 201 is configured to emit electrons from the cathode as primary electrons. The primary electrons are extracted or accelerated by the extractor and / or the anode to form a primary electron beam 202, which forms a primary beam cross (virtual or real) 203. The primary electron beam 202 can be visualized as being emitted from the primary beam cross 203.

[0057] In this arrangement, the primary electron beam is multi-beamed as it reaches the sample (and preferably before it reaches the projection device). This multi-beam can be generated from the primary electron beam in a variety of different ways. For example, the multi-beam can be generated by a multi-beam array located before the crossover, a multi-beam array located in the source conversion unit 220, or a multi-beam array located at any point between these locations. The multi-beam array may include multiple electron beam manipulation elements arranged in an array across the beam path. Each manipulation element can influence the primary electron beam to generate a sub-beam. Thus, the multi-beam array interacts with the incident primary beam path to generate a multi-beam path downstream of the multi-beam array.

[0058] In operation, the aperture plate 271 is configured to block peripheral electrons in the primary electron beam 202 to reduce the Coulomb effect. The Coulomb effect can amplify the size of each probe spot in the probe spots 221, 222, and 223 of the primary sub-beams 211, 212, and 213, thus reducing the inspection resolution. The aperture plate 271 may also be referred to as a Coulomb aperture array.

[0059] The focusing lens 210 is configured to focus the primary electron beam 202. The focusing lens 210 can be designed to focus the primary electron beam 202 into a parallel beam and incident perpendicularly onto the source conversion unit 220. The focusing lens 210 can be a movable focusing lens, configured such that the position of its first principal plane is movable. The movable focusing lens can be configured to be magnetic. The focusing lens 210 can be an anti-rotation focusing lens and / or it can be movable.

[0060] Source conversion unit 220 may include an image forming element array, an aberration compensator array, a beam confinement aperture array, and a pre-bending micro-deflector array. The pre-bending micro-deflector array can deflect multiple primary sub-beams 211, 212, 213 of the primary electron beam 202 to enter the beam confinement aperture array, the image forming element array, and the aberration compensator array perpendicularly. In this arrangement, the image forming element array can function as a multi-beam array to generate multiple sub-beams, i.e., primary sub-beams 211, 212, 213, in a multi-beam path. The image forming array may include multiple electron beam manipulators, such as micro-deflectors or microlenses (or a combination of both), to influence the multiple primary sub-beams 211, 212, 213 of the primary electron beam 202 and form multiple parallel images (virtual or real) of the primary beam cross 203, each primary sub-beam of 211, 212, and 213 corresponding to one parallel image. The aberration compensator array may include a field curvature compensator array (not shown) and an astigmatism compensator array (not shown). The field curvature compensator array may include multiple microlenses to compensate for field curvature aberrations in primary sub-beams 211, 212, and 213. The astigmatism compensator array may include multiple micro-astigmatism reducers to compensate for astigmatic aberrations in primary sub-beams 211, 212, and 213. The beam-limiting aperture array may be configured to limit the diameters of the individual primary sub-beams 211, 212, and 213. Figure 2 Three primary sub-bundles 211, 212, and 213 are shown as examples, and it should be understood that the source conversion unit 220 can be configured to form any number of primary sub-bundles. The controller 50 can be connected to... Figure 1 The charged particle beam inspection equipment 100 includes various components such as the source conversion unit 220, the electronic detection device 240, the primary projection device 230, or the motorized stage 209. As explained in further detail below, the controller 50 can perform various image and signal processing functions. The controller 50 can also generate various control signals to manage the operation of the charged particle beam inspection equipment (including charged particle multi-beam equipment).

[0061] The focusing lens 210 can also be configured to adjust the current of the primary sub-bundles 211, 212, 213 downstream of the source conversion unit 220 by changing the focusing capability of the focusing lens 210. Alternatively, or additionally, the current of the primary sub-bundles 211, 212, 213 can be changed by altering the radial dimension of the beam-limiting aperture within the beam-limiting aperture array corresponding to each primary sub-bundle. The current can be changed by altering the radial dimension of the beam-limiting aperture and the focusing capability of the focusing lens 210. If the focusing lens is movable and magnetic, the off-axis sub-bundles 212 and 213 can cause the source conversion unit 220 to be illuminated at a rotational angle. The rotational angle changes with the focusing capability of the movable focusing lens or the position of the first principal plane. The focusing lens 210, acting as an anti-rotation focusing lens, can be configured to maintain a constant rotational angle when the focusing capability of the focusing lens 210 changes. When the focusing capability of the focusing lens 210 and the position of its first principal plane change, this movable focusing lens 210 can maintain the rotation angle.

[0062] Objective 231 can be configured to focus sub-beams 211, 212 and 213 onto sample 208 for inspection, and can form three probe spots 221, 222 and 223 on the surface of sample 208.

[0063] Beam splitter 233 may be, for example, a Wien filter including an electrostatic deflector that generates an electrostatic dipole field and a magnetic dipole field. Figure 2 (Not shown in the image). In operation, the beam splitter 233 can be configured to apply electrostatic forces to the individual electrons of the primary sub-bundles 211, 212, and 213 via an electrostatic dipole field. The electrostatic forces are equal in magnitude but opposite in direction to the magnetic forces applied to the individual electrons by the magnetic dipole field of the beam splitter 233. Therefore, the primary sub-bundles 211, 212, and 213 can pass through the beam splitter 233 at least substantially straight with at least substantially zero deflection angle.

[0064] In operation, deflection scanning unit 232 is configured to deflect primary sub-beams 211, 212, and 213 to scan probe spots 221, 222, and 223 across various scanning regions in the surface portion of sample 208. In response to the incidence of primary sub-beams 211, 212, and 213 or probe spots 221, 222, and 223 on sample 208, electrons comprising secondary electrons and backscattered electrons are generated from sample 208. The secondary electrons propagate in three secondary electron beams 261, 262, and 263. Secondary electron beams 261, 262, and 263 typically contain secondary electrons (with electron energies ≤50 eV) and may also contain at least some of backscattered electrons (with electron energies between 50 eV and the landing energies of primary sub-beams 211, 212, and 213). Beam splitter 233 is arranged to deflect the paths of secondary electron beams 261, 262, and 263 toward secondary projection device 250. Secondary projection device 250 then focuses the paths of secondary electron beams 261, 262, and 263 onto multiple detection regions 241, 242, and 243 of electron detection device 240. Detection regions may be individual detection elements 241, 242, and 243 configured to detect corresponding secondary electron beams 261, 262, and 263. Detection regions generate corresponding signals, which are sent to controller 50 or signal processing system (not shown), for example, to construct an image of the corresponding scanned region of sample 208.

[0065] Detection elements 241, 242, and 243 can detect corresponding secondary electron beams 261, 262, and 263. When the secondary electron beams are incident on detection elements 241, 242, and 243, these elements can generate corresponding intensity signal outputs (not shown). The outputs can be directed to an image processing system (e.g., controller 50). Each detection element 241, 242, and 243 can include one or more pixels. The intensity signal output of the detection element can be the sum of signals generated by all pixels within the detection element.

[0066] The controller 50 may include an image processing system comprising an image acquirer (not shown) and a storage device (not shown). For example, the controller may include a processor, computer, server, mainframe, terminal, personal computer, any type of mobile computing device, or combinations thereof. The image acquirer may include at least a portion of the controller's processing capabilities. Therefore, the image acquirer may include at least one or more processors. The image acquirer may be communicatively coupled to an electronic detection device 240 of a device 40 that allows signal communication, such as an electrical conductor, fiber optic cable, portable storage medium, IR, Bluetooth, the Internet, wireless network, radio, or combinations thereof. The image acquirer may receive signals from the electronic detection device 240, process data included in the signals, and construct an image from them. Thus, the image acquirer can acquire an image of sample 208. The image acquirer may also perform various post-processing functions, such as generating contours, overlaying indicators on the acquired image, etc. The image acquirer 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, flash drive, cloud storage, random access memory (RAM), other types of computer-readable storage, etc. The storage device can be coupled to the image acquirer and can be used to save the scanned raw image data as an initial image and to save a post-processed image.

[0067] The image acquirer can acquire one or more images of a sample based on imaging signals received from the electronic detection device 240. The imaging signals may correspond to a scanning operation used for imaging charged particles. The acquired image may be a single image comprising multiple imaging regions. The single image may be stored in a storage device. The single image may be an initial image that can be divided into multiple regions. Each of these regions may include an imaging region containing features of the sample 208. The acquired images may include multiple images of a single imaging region of the sample 208 sampled multiple times over a period of time. Multiple images may be stored in a storage device. The controller 50 may be configured to perform image processing steps using multiple images of the same location on the sample 208.

[0068] The controller 50 may include a measurement circuitry system (e.g., an analog-to-digital converter) to obtain the distribution of detected secondary electrons. The electron distribution data collected during the detection time window can be combined with corresponding scan path data of each of the primary sub-beams 211, 212, and 213 incident on the sample surface to reconstruct an image of the sample structure under examination. The reconstructed image can be used to reveal various features of the internal or external structure of the sample 208. Therefore, the reconstructed image can be used to reveal any defects that may be present in the sample.

[0069] The controller 50 can control the motorized stage 209 to move the sample 208 during sample inspection. At least during sample inspection, the controller 50 can cause the motorized stage 209 to move the sample 208 in a certain direction, for example, at a constant speed, preferably continuously. The controller 50 can control the movement of the motorized stage 209 such that it changes the speed of the sample 208 according to various parameters. For example, the controller can control the stage speed (including its direction) based on the characteristics of the inspection steps in the scanning process.

[0070] although Figure 2 The device 40 is shown to use three primary electron sub-beams; however, it should be understood that the device 40 may use two or more primary electron sub-beams. This disclosure does not limit the number of primary electron beams used in the device 40.

[0071] Now for reference Figure 3 , Figure 3 It's a diagram. Figure 1 A schematic diagram of an exemplary multi-beam device with an exemplary configuration of the source conversion unit of an exemplary charged particle beam inspection apparatus. The apparatus 300 may include an electron source 301, a pre-beam forming aperture array 372, and a focusing lens 310 (similar to...). Figure 2 (Converging lens 210), source conversion unit 320, objective lens 331 (similar to) Figure 2 Objective 231) and sample 308 (similar to) Figure 2 (Sample 208). The electron source 301, pre-beam forming aperture array 372, and focusing lens 310 can be components of the irradiation device included in the device 300. The source conversion unit 320 and objective lens 331 can be components of the projection device included in the device 300. The source conversion unit 320 can be similar to... Figure 2 The source conversion unit 220, wherein Figure 2 The image forming element array is an image forming element array 322. Figure 2 The aberration compensator array is an aberration compensator array 324. Figure 2 The beam-confined aperture array is a beam-confined aperture array 321. Figure 2The pre-bending micro-deflector array is a pre-bending micro-deflector array 323. An electron source 301, a pre-beamforming aperture array 372, a focusing lens 310, a source conversion unit 320, and an objective lens 331 are aligned with the primary electron optical axis 304 of the device. The electron source 301 generates a primary electron beam 302 that is generally along the primary electron optical axis 304 and has source crossovers (virtual or real) 301S. The pre-beamforming aperture array 372 cuts the peripheral electrons of the primary electron beam 302 to reduce the Coulomb effect that occurs as a result. The Coulomb effect is a source of aberrations in the sub-beams due to the interaction between electrons in different sub-beam paths. Through the pre-beamforming aperture array 372 of the pre-beamforming mechanism, the primary electron beam 302 can be trimmed into a specified number of sub-beams, such as three sub-beams 311, 312, and 313. Although three sub-bundles and their paths are mentioned in the preceding and following descriptions, it should be understood that this description is intended to apply to devices, tools, or systems with any number of sub-bundles.

[0072] Source conversion unit 320 may include a sub-beam limiting aperture array 321 having a beam limiting aperture configured to limit sub-beams 311, 312, and 313 of the primary electron beam 302. Source conversion unit 320 may also include an image forming element array 322 having image forming micro-deflectors 322_1, 322_2, and 322_3. A corresponding micro-deflector is associated with the path of each sub-beam. Micro-deflectors 322_1, 322_2, and 322_3 are configured to deflect the paths of sub-beams 311, 312, and 313 toward the electron optical axis 304. The deflected sub-beams 311, 312, and 313 form a virtual image of the source cross 301S. The virtual image is projected onto the sample 308 through objective lens 331, and detector spots are formed thereon, which are three detector spots 391, 392, and 393. Each probe spot corresponds to the incident position of the sub-beam path on the sample surface. The source conversion unit 320 may also include an aberration compensator array 324 configured to compensate for aberrations in each sub-beam. Aberrations in each sub-beam are typically present in probe spots 391, 392, and 393 that will be formed on the sample surface. The aberration compensator array 324 may include an array of field curvature compensators (not shown) with microlenses. The field curvature compensators and microlenses are configured to compensate for sub-beams with significant field curvature aberrations in probe spots 391, 392, and 393. The aberration compensator array 324 may include an array of astigmatism compensators (not shown) with micro-astigmatism ablation devices. The micro-astigmatism ablation devices are controlled to operate on the sub-beams to compensate for astigmatic aberrations that are otherwise present in probe spots 391, 392, and 393.

[0073] The source conversion unit 320 may further include a pre-bent micro-deflector array 323 having pre-bent micro-deflectors 323_1, 323_2, and 323_3 to bend sub-beams 311, 312, and 313, respectively. The pre-bent micro-deflectors 323_1, 323_2, and 323_3 can bend the paths of the sub-beams onto the sub-beam confinement aperture array 321. The sub-beam paths incident on the sub-beam confinement aperture array 321 can be orthogonal to the plane of orientation of the sub-beam confinement aperture array 321. A focusing lens 310 can guide the paths of the sub-beams onto the sub-beam confinement aperture array 321. The focusing lens 310 can focus the three sub-beams 311, 312, and 313 into parallel beams along the primary electron optical axis 304, such that they are perpendicularly incident on the source conversion unit 320, which can correspond to the sub-beam confinement aperture array 321.

[0074] The image forming element array 322, the aberration compensator array 324, and the pre-bending micro-deflector array 323 may include multi-layer sub-beam manipulation devices, some of which may be in the form of arrays, such as micro-deflectors, microlenses, or micro-astigmatism reducers.

[0075] In the source conversion unit 320, sub-beams 311, 312, and 313 of the primary electron beam 302 are deflected toward the primary electron optical axis 304 by micro-deflectors 322_1, 322_2, and 322_3 of the image forming element array 322, respectively. It should be understood that the path of sub-beam 311 may already correspond to the electron optical axis 304 before reaching the micro-deflector 322_1, and therefore the path of sub-beam 311 may not be deflected by the micro-deflector 322_1.

[0076] Objective lens 331 focuses the sub-beams onto the surface of sample 308, i.e., it projects three virtual images onto the sample surface. The three images formed by the three sub-beams 311 to 313 on the sample surface form three probe spots 391, 392, and 393 thereon. The deflection angles of the sub-beams 311 to 313 are adjusted by objective lens 331 to reduce off-axis aberrations of the three probe spots 391 to 393. The three deflected sub-beams thus pass through or approach the front focal point of objective lens 331. As depicted, objective lens 331 is a magnetic lens that focuses all the sub-beams. In one embodiment of the invention, the objective lens is preferably an array of electrostatic lenses that may require guiding multiple beam paths from source conversion unit 320 (in particular, image forming element array 322 characterized, for example, by micro-deflectors) toward the array of electrostatic lenses in objective lens 331. (Each beam may be guided toward its own corresponding microlens in the array).

[0077] Figure 2 and Figure 3At least some of the aforementioned components may be referred to individually or in combination as a manipulator array, a multi-manipulator array, a multi-manipulator, or a manipulator, because they manipulate one or more beams or sub-beams of charged particles.

[0078] Existing multi-electron beam defect inspection systems have a speed of 10 to 6000 mm per hour. 2 The system achieves a resolution of approximately 2 to 10 nm at high throughput. Such a system incorporates a detector in a secondary column as described above. Existing multi-electron-beam inspection tools have detectors located far from the source of electrons emitted from the sample (such as backscattered and secondary electrons), which is not scalable for many beam systems. Integrating the secondary column into a tool with array objectives (such as electrostatic lenses) is also challenging (as this is necessary to resolve Coulomb interactions).

[0079] In one embodiment, the objective lens mentioned in the preceding embodiments is an array objective lens. Typically, this lens arrangement is electrostatic. Each element in the array is a microlens that operates on a different beam or group of beams in a multi-beam array. The electrostatic array objective lens has at least two plates, each plate having multiple holes or apertures. The position of each hole in one plate corresponds to the position of a corresponding hole in the other plate. The corresponding holes operate on the same beam or group of beams in the multi-beam array during use. A suitable example of the type of lens used for each element in the array is a single lens. The bottom electrode of the objective lens is a CMOS chip detector integrated into the multi-beam manipulator array. Integrating the detector array into the objective lens eliminates the need for a secondary projection device 250. The CMOS chip is preferably oriented to face the sample (due to the small distance (e.g., 100 μm) between the wafer and the bottom of the electro-optics system). In one embodiment, a capture electrode is provided for capturing secondary electronic signals. The capture electrode can be formed in a metal layer, for example, of a CMOS device. The capture electrode can form the bottom layer of the objective lens. The capture electrode can form the bottom surface of the CMOS chip. The CMOS chip can be a CMOS chip detector. A CMOS chip can be integrated into the sample-facing surface of the objective lens assembly. A trapping electrode is an example of a sensor unit used to detect secondary electrons. The trapping electrode can be formed in other layers. The CMOS's power and control signals can be connected to the CMOS via through-silicon vias (TSVs). For robustness, the bottom electrode preferably consists of two elements: the CMOS chip and a passive Si substrate with vias. This substrate shields the CMOS from high electric fields.

[0080] A sensor unit associated with the bottom of the objective lens or the sample-facing surface is advantageous because secondary and / or backscattered electrons can be detected before they are encountered and manipulated by the electro-optical elements of the electro-optical system. Advantageously, the time spent detecting such emitted electrons in the sample can preferably be minimized.

[0081] To maximize detection efficiency, it is desirable to make the electrode surface as large as possible, such that the electrodes occupy virtually all of the array objective (except for the aperture). Each electrode can have a diameter substantially equal to the array spacing. The electrode surface can substantially fill the sample-facing surface of the array objective. In one embodiment, the outer shape of the electrodes is circular, but this can be made square to maximize the detection area. It is also possible to minimize the diameter of the aperture through the substrate. Typical electron beam sizes are on the order of 55 to 15 micrometers.

[0082] In one embodiment, a single capture electrode surrounds each aperture. The single capture electrode may have a circular periphery and / or outer diameter. The capture electrode may have a region extending between the aperture and the periphery of the capture electrode. Figure 5 and Figure 6 As shown, the capturing electrodes 405 can be arranged in a rectangular or hexagonal array. In another embodiment, multiple electrode elements are disposed around each aperture. The multiple electrode elements may together have a circular perimeter and / or diameter. The multiple electrode elements may together have a region extending between the aperture and the perimeter of the multiple electrode elements. The multiple electrode elements 405 can be arranged in a rectangular or hexagonal array. The electrode elements are examples of sensor elements. Electrons captured by the electrode elements surrounding an aperture can be combined into a single signal or used to generate independent signals. The electrode elements can be radially divided. The electrode elements can form multiple concentric rings or loops. The electrode elements can be angularly divided. The electrode elements can form multiple fan-shaped plates or segments. These segments can have similar angular dimensions and / or similar areas. The electrode elements can be radially and angularly divided or in any other convenient manner.

[0083] However, a larger electrode surface area results in larger parasitic capacitance, thus leading to lower bandwidth. For this reason, it may be desirable to limit the outer diameter of the electrode, especially when a larger electrode only provides slightly higher detection efficiency but results in significantly larger capacitance. Circular (ring-shaped) electrodes offer a good trade-off between collection efficiency and parasitic capacitance.

[0084] A larger outer diameter of the electrode can also lead to greater crosstalk (sensitivity to signals from adjacent holes). This may also be a reason to reduce the outer diameter of the electrode, especially when a larger electrode only provides slightly higher detection efficiency but results in significantly greater crosstalk.

[0085] The backscattered and / or secondary electron flow collected by the electrodes is amplified. The purpose of the amplifier is to enable sufficiently sensitive measurement of the current to be measured, received or collected by the sensor unit, thus measuring the number of backscattered and / or secondary electrons. This can be measured by current measurement or the potential difference across a resistor. Several types of amplifier designs can be used to amplify the backscattered and / or secondary electron flow collected by the electrodes, such as a transimpedance amplifier. In such a transimpedance amplifier, the voltage output of the TIA is equal to the resistance of the TIA (R). TIA Multiply by the measured current.

[0086] R TIA The larger the value, the higher the amplification. However, the bandwidth is determined by the RC time, which is equal to R. TIA Multiply by the sum of the capacitances at the TIA input side.

[0087] A finite RC time has a similar effect to a large electron optical spot size, thus effectively imparting a blurring effect in the deflection direction. Given the detector's blurring effect budget and deflection speed, determine the allowable RC time. Given this RC time and the input capacitance R... TIA .

[0088] Based on backscattering and / or secondary electron flow and R TIA Determine the signal voltage.

[0089] The noise contribution of the detector should be compared with the shot noise of the backscattered and / or secondary electron beams. Considering only the shot noise of the primary electron beam, the current noise per sqrt(Hz) caused by shot noise is significantly greater than the voltage noise of prior art CMOS amplifiers (typically ~1 nV / sqrt(Hz)), as shown below. The rough calculations given below demonstrate that the proposed electrode is feasible from a noise point of view.

[0090] N PE_def =5000 (1)

[0091] I beam =1nA (2)

[0092] d def =4nm (3)

[0093] N pix_defect =4 (4)

[0094] blur rc =0.5nm (5)

[0095]

[0096]

[0097]

[0098]

[0099]

[0100]

[0101]

[0102]

[0103]

[0104] The above calculations can be explained as follows. Assume the number of secondary electrons required to detect a defect is 5000 (Equation 1), the beam current is 1 nA (Equation 2), the defect diameter is 4 nm (Equation 3), and the number of pixels per defect is 4 (Equation 4). We assume that the blurring caused by the finite RC time of the 0.5 nm amplifier is acceptable (Equation 5). The detector capacitance can be calculated based on the geometry of the arrangement, for example, as shown in Equation 6, where 3 is the dielectric constant of the insulator below the trapping electrode, 100 μm is the diameter of the trapping electrode, and 1 μm is the thickness of the insulator below the trapping electrode. Inherent shot noise is calculated as in Equation 7. The imaging time for a defect is calculated as in Equation 8, where Qe is the electron charge. The scan length for detecting the defect is calculated as in Equation 9, and the scan speed is calculated as in Equation 10. The RC time to be achieved is calculated as in Equation 11, therefore the detector resistance is calculated as in Equation 12, and the resulting voltage noise is calculated as in Equation 13. Equation 14 combines the previous equations into a single equation to demonstrate the correlation. Typical voltage noise levels achievable in CMOS amplifiers are on the order of 1 nV / sqrt(Hz), which is typical for CMOS amplifiers. Therefore, it is reasonable that the noise is dominated by fundamental shot noise rather than by voltage noise added by the CMOS amplifier. Thus, from a noise point of view, the proposed electrode is feasible. That is, typical CMOS amplifier noise is good enough to have a relatively low noise level relative to shot noise. (Even if it were higher relative to shot noise, the arrangement could still work, but this would reduce its effectiveness in terms of bandwidth or throughput (i.e., speed).

[0105] Figure 8 This is a schematic diagram of a theoretical transimpedance amplifier (TIA), where the voltage output V... out Simply put, it measures the current I. in and feedback resistor R f The product of . However, the real TIA has noise, especially the input i snShot noise and feedback resistor i n Thermal noise in, such as Figure 9 As shown. In most cases, thermal noise dominates. Output v n The voltage noise at that point is given by the following formula:

[0106]

[0107] Where k b This is the Boltzmann constant. Therefore, the current noise at the TIA inlet is:

[0108]

[0109] Shot noise is given by the following formula:

[0110]

[0111] Therefore, if the feedback resistance is increased, the shot noise of thermal noise relative to the input current (i.e., backscattered and / or secondary electron flow) becomes lower.

[0112] It can be seen that, by assuming the number of electrons required to detect each defect increases to 10,000, and considering the effect of shot noise, this invention remains practical; a fuzzy budget of 2 nm is set; and the electrode diameter is reduced to 50 μm. In this case, the electrode capacitance becomes approximately 0.011 pF, requiring approximately 3.6 × 10⁻⁶ pF. 7 The resistance of Ω results in a thermal noise level approximately 20% higher than shot noise. Therefore, various arrangements of the proposed detector are feasible. The capacitance of the electrodes can also be controlled by varying the thickness of the adjacent dielectric layer, which can range from approximately 1 to approximately 5 μm.

[0113] Figure 4 An exemplary embodiment is shown in the figure. Figure 4 A schematic cross-section of the multibeam objective lens 401 is shown. A detector module 402 is provided on the output side of the objective lens 401, i.e., the side facing the sample 208. Figure 5 This is a bottom view of detector module 402, which includes a substrate 404 on which a plurality of trapping electrodes 405 are provided, each trapping electrode 405 surrounding a beam aperture 406. The beam aperture 406 is large enough not to block any electrons from the primary electron beam. The trapping electrodes 405 can be considered as examples of sensor units that receive backscattered or secondary electrodes and generate a detection signal (in this case, a current). The beam aperture 406 can be formed by etching through the substrate 404. Figure 5 In the arrangement shown, the beam aperture 406 is displayed in a rectangular array. The beam aperture 406 can also be arranged differently, for example, as shown in... Figure 6 The hexagonal close-packed array shown is used for arrangement.

[0114] Figure 7 A cross-section of a portion of detector module 402 is depicted at a larger scale. The capture electrode 405 forms the bottommost surface of detector module 402, i.e., closest to the sample. A logic layer 407 is provided between the capture electrode 405 and the body of silicon substrate 404. Logic layer 407 may include amplifiers, such as transimpedance amplifiers, analog-to-digital converters, and readout logic. In one embodiment, each capture electrode 405 contains one amplifier and one analog-to-digital converter. Logic layer 407 and capture electrodes 405 can be fabricated using CMOS processes, wherein capture electrodes 405 form the final metallization layer.

[0115] Wiring layer 408 is disposed on the back side of substrate 404 and connected to logic layer 407 via through-silicon vias (TSVs) 409. The number of TSVs 409 need not be the same as the number of apertures 406. In particular, if electrode signals are digitized in logic layer 407, only a small number of TSVs may be needed to provide the data bus. Wiring layer 408 may include control lines, data lines, and power lines. It should be noted that despite the apertures 406, there is sufficient space for all necessary connections. Detection module 402 can also be fabricated using bipolar or other manufacturing techniques. Printed circuit boards and / or other semiconductor chips can be provided on the back side of detector module 402.

[0116] Figure 4 Three electrode objectives are depicted, but it should be understood that any other type of objective, such as two electrode lenses, may also be used.

[0117] Now for reference Figure 10 , Figure 10 This is a schematic diagram illustrating another exemplary electron beam tool 40a, which may be... Figure 1 A portion of the exemplary charged particle beam inspection device 100, replacing Figure 2 Tool 40. With Figure 2 Parts of device 40 that have similar functions to those of device 40a are indicated by the same reference numerals. Simplified or abbreviated descriptions of these parts are included in some of the following cases.

[0118] The multi-beam electron beam tool 40a (also referred to herein as apparatus 40a) includes an electron source 201, a projection device 230, a motorized stage 209, and a sample holder 207. The electron source 201 and the projection device 230 may be collectively referred to as an irradiation apparatus. The sample holder 207 is supported by the motorized stage 209 to hold a sample 208 (e.g., a substrate or mask) for inspection. The multi-beam electron beam tool 40a also includes an electron detection device 1240. (Note that this may differ structurally from the reference design.) Figure 2 and Figure 3The electron detection device 240 in the secondary electron-optical array of the mentioned embodiment, although it has the same function: detecting electrons from the sample.

[0119] The electron source 201 may include a cathode (not shown) and an extractor or anode (not shown). During operation, the electron source 201 is configured to emit electrons from the cathode as primary electrons. The primary electrons are extracted or accelerated by the extractor and / or anode to form a primary electron beam 202.

[0120] The projection device 230 is configured to convert the primary electron beam 202 into multiple sub-beams 211, 212, and 213, and to direct each sub-beam onto the sample 208. Although three sub-beams are shown for simplicity, there can be tens, hundreds, or thousands of sub-beams. Sub-beams may be referred to as beam splitting.

[0121] Figure 1 The controller 50 can be connected to various parts of the electron beam tool 40a, such as the electron source 201, the electron detection device 1240, the projection device 230, and the motorized stage 209. The controller 50 can perform various image and signal processing functions. The controller 50 can also generate various control signals to manage the operation of the charged particle beam inspection equipment (including charged particle multi-beam equipment).

[0122] Projection device 230 can be configured to focus sub-beams 211, 212, and 213 onto sample 208 for inspection, and can form three probe spots 221, 222, and 223 on the surface of sample 208. Projection device 230 can be configured to deflect primary sub-beams 211, 212, and 213 to scan probe spots 221, 222, and 223 across respective scanning regions in the surface portion of sample 208. In response to the incident incidence of primary sub-beams 211, 212, and 213 on sample 208 at probe spots 221, 222, and 223, electrons comprising secondary electrons and backscattered electrons are generated from sample 208. Secondary electrons typically have electron energies ≤50 eV, and backscattered electrons typically have electron energies between 50 eV and the landing energies of primary sub-beams 211, 212, and 213.

[0123] The electron detection device 1240 is configured to detect secondary electrons and / or backscattered electrons and generate corresponding signals that are sent to a controller or signal processing system (not shown), for example, to construct an image of a corresponding scan area of ​​the sample 208. The electron detection device 1240 may include components as referenced above. Figures 4 to 7 The objective lens 401 integrates a detector module 402.

[0124] Figure 11 This is a schematic diagram illustrating another exemplary electron beam tool 40b, which may be... Figure 1 A portion of the exemplary charged particle beam inspection device 100, replacing Figure 2 Tool 40. With Figure 2 The corresponding parts of device 40 that have similar functions to those of device 40a are indicated by the same reference numerals. Simplified or abbreviated descriptions of these parts are included in some of the following cases.

[0125] An electron source 201 directs electrons toward an array of focusing lenses 1231 that form part of the projection system 230. The electron source is desired to be a high-brightness thermal field emitter with a good trade-off between brightness and total emission flux. Tens, hundreds, or thousands of focusing lenses 1231 may be present. The focusing lenses 1231 may include multi-electrode lenses and have a construction based on EP 1602121A1, which is hereby specifically incorporated by reference to the disclosure of a lens array for splitting an electron beam into multiple sub-beams, wherein the array provides a lens for each sub-beam. The focusing lens array may take the form of at least two plates (used as electrodes), with apertures in each plate aligned with each other and corresponding to the positions of the sub-beams. During operation, at least two plates are maintained at different potentials to achieve the desired lensing effect.

[0126] In one arrangement, the condenser lens array is formed by three plate arrays, where charged particles have the same energy as when they enter and exit each lens; this arrangement can be called a single lens. The beam energy is the same when entering and exiting a single lens. Therefore, dispersion occurs only within the single lens itself (between the lens's entrance and exit electrodes), thus limiting off-axis chromatic aberration. When the thickness of the condenser lens is small, such as a few millimeters, this aberration has a small or negligible effect.

[0127] The focusing lens array may include multiple beam apertures 110. Beam apertures 110 may be formed, for example, by openings in a substantially planar beam aperture body 111. Beam apertures 110 split the charged particle beam from source 201 into corresponding sub-beams. Each focusing lens in the array guides electrons into a corresponding sub-beam 1211, 1212, 1213, which is focused at a corresponding intermediate focal point 1233. At the intermediate focal point 1233 is a deflector 235. Deflector 235 is configured to bend the corresponding sub-beams 1211, 1212, 1213 by an effective amount to ensure that the main ray (which may also be referred to as the beam axis) is incident substantially perpendicularly (i.e., substantially at 90° to the nominal surface of the sample) onto sample 208. Deflector 235 may also be referred to as a collimator. Downstream of the central focal point 1233 (i.e. closer to the sample) are multiple objectives 1234, each of which guides a corresponding sub-beam 1211, 1212, 1213 onto the sample 208. Objectives 1234 can be configured to reduce the electron beam by a factor greater than 10 (ideally in the range of 50 to 100 or greater).

[0128] An electron detection device 1240 is disposed between the objective lens 1234 and the sample 208 to detect secondary and / or backscattered electrons emitted from the sample 208. The electron detection device 1240 may include components as referenced above. Figures 4 to 7 The objective lens 401 integrates a detector module 402. The electronic detection device 1240 may include a sensor unit, such as a capture electrode 405.

[0129] Figure 11 The system can be configured to control the landing energy of electrons on a sample. The landing energy can be selected based on the properties of the sample being evaluated to increase the emission and detection of secondary electrons. The controller provided to control the objective lens 1234 can be configured to control the landing energy to any desired value or a desired value among a plurality of predetermined values ​​within a predetermined range. In one embodiment, the landing energy can be controlled to a desired value in the range of 1000 eV to 5000 eV. Details of the electrode structure and potential that may be used to control the landing energy are disclosed in EPA 20158804.3, which is incorporated herein by reference.

[0130] In some embodiments, the charged particle evaluation tool further includes one or more aberration correctors that reduce one or more aberrations in the sub-beam. In one embodiment, each aberration corrector in at least a subset of the aberration correctors is located at or directly adjacent to a corresponding intermediate focal point (e.g., in or near the intermediate image plane). The sub-beam has a minimum cross-sectional area in or near a focal plane such as the intermediate plane. This provides more space for the aberration correctors than is available elsewhere (i.e., upstream (closer to the source) or downstream (closer to the sample) of the intermediate plane) (or more than would be available in alternative arrangements without an intermediate image plane).

[0131] In one embodiment, an aberration corrector positioned at or directly adjacent to the intermediate focal point (or intermediate image plane) includes a deflector to correct for source 201 appearing to be in different positions for different beams. The corrector can be used to correct macroscopic aberrations generated by the source that hinder proper alignment between each sub-beam and its corresponding objective.

[0132] An aberration corrector can correct aberrations that hinder proper column alignment. Such aberrations can also cause misalignment between the sub-bundles and the corrector. For this reason, it may be desirable to additionally or alternatively position the aberration corrector at or near the focusing lens 1231 (e.g., where each such aberration corrector is integrated with or directly adjacent to one or more focusing lenses in the focusing lens 1231). This is desirable because at or near the focusing lens 1231, aberrations do not yet cause offset of the corresponding sub-bundles, as the focusing lens 1231 is longitudinally close to or coincides with the beam aperture. However, the challenge of positioning the corrector at or near the focusing lens 1231 is that the sub-bundles at that location have relatively large cross-sectional areas and relatively small spacing compared to more downstream locations. The aberration corrector can be individual CMOS-based programmable deflectors as disclosed in EP2702595A1 or a multi-pole deflector array as disclosed in EP2715768A2, in which descriptions of the beam manipulators are incorporated herein by reference.

[0133] In some embodiments, each aberration corrector in at least a subset of the aberration correctors is integrated with or directly adjacent to one or more objectives in objective 1234. In one embodiment, these aberration correctors reduce one or more of the following: field curvature; focusing error; and astigmatism. Additionally or alternatively, one or more scan deflectors (not shown) may be integrated with or directly adjacent to one or more objectives in objective 1234 for scanning sub-beams 1211, 1212, 1213 on sample 208. In one embodiment, the scan deflector described in US2010 / 0276606 may be used, which is incorporated herein by reference in its entirety.

[0134] In one embodiment, the objective lens mentioned in the preceding embodiments is an array objective lens. Each element in the array is a microlens that operates on different beams or groups of beams in a multi-beam array. An electrostatic array objective lens has at least two plates, each plate having multiple holes or apertures. The position of each hole in one plate corresponds to the position of a corresponding hole in the other plate. The corresponding holes operate on the same beam or group of beams in the multi-beam array during use. A suitable example of the type of lens used for each element in the array is a dual-electrode deceleration lens.

[0135] An electron detection device 1240 is disposed between the objective lens 1234 and the sample 208 to detect secondary and / or backscattered electrons emitted from the sample 208. The electron detection device may include, as referenced above... Figures 4 to 7 The objective lens 401 integrates a detector module 402. The electronic detection device 240 may include a sensor unit, such as a capture electrode 405.

[0136] In an embodiment of the invention, the corrector 235 at the intermediate focal point 1233 is implemented by a slit deflector 300. The slit deflector 300 is an example of a manipulator and may also be referred to as a slit corrector.

[0137] exist Figure 12 Another exemplary electron beam tool 40c is schematically illustrated in the figure. The electron beam tool 40c may be... Figure 1 A portion of the exemplary charged particle beam inspection device 100, replacing Figure 2 Tool 40. With Figure 2 The corresponding parts of device 40 that have similar functions to those of device 40a are indicated by the same reference numerals. Simplified or abbreviated descriptions of these parts are included in some of the following cases.

[0138] Tool 40c also includes one or more aberration correctors 124, 125, 126 that reduce one or more aberrations in sub-bundles 114. In one embodiment, each aberration corrector in at least a subset of aberration correctors 124 is positioned at or directly adjacent to a corresponding intermediate focal point in intermediate focal point 115 (e.g., in or near intermediate image plane 120). Sub-bundles 114 have a minimal cross-sectional area in or near a focal plane such as intermediate image plane 120. This provides aberration correctors 124 with more space than is available elsewhere (i.e., upstream or downstream of intermediate image plane 120) (or more than in alternative arrangements without intermediate image plane 120).

[0139] In one embodiment, the aberration corrector 124, located at or directly adjacent to the intermediate focal point 115 (or intermediate image plane 120), includes a deflector to correct for different sub-beams 114 derived from the beam 112 emitted from the source 201, which appear to be located at different positions. The corrector 124 can be used to correct macroscopic aberrations generated by the source 201 that hinder proper alignment between each sub-beam 114 and its corresponding objective lens 118.

[0140] Aberration corrector 124 can correct aberrations that hinder proper column alignment. Such aberrations can also cause misalignment between sub-bundles 114 and corrector 124. For this reason, it may be desirable to additionally or alternatively position aberration correctors 125 at or near convergent lenses 116 (e.g., where each such aberration corrector 125 is integrated with or directly adjacent to one or more convergent lenses in the convergent lenses 116). This is desirable because at or near convergent lenses 116, aberrations do not yet cause offset of the corresponding sub-bundles 114, since convergent lenses 116 are longitudinally close to or coincident with beam aperture 110. However, the challenge in positioning correctors 125 at or near convergent lenses 116 is that, relative to more downstream locations, sub-bundles 114 each have a relatively large cross-sectional area and relatively small spacing at that location.

[0141] In some embodiments, such as Figure 12 As shown, each aberration corrector in at least a subset of aberration correctors 126 is integrated with or directly adjacent to one or more objectives in the objectives 118. In one embodiment, these aberration correctors 126 reduce one or more of the following: field curvature; focusing error; and astigmatism. Figure 12 In the device, any or all of the correctors 124, 125, and 126 can be slit deflectors.

[0142] Figure 13 and Figure 14Another example of an electronic detection device 240 that can be used in embodiments of the present invention is depicted, for example, which can be incorporated herein by reference. Figure 2 , Figure 10 , Figure 11 and Figure 12 Among the electron beam tools 40, 40a, 40b, and 40c. Figure 13 This is a schematic side view of the electronic detection device 240 integrated into or associated with the objective lens array 501. Figure 14 This is a view taken from below the electronic detection device 240.

[0143] like Figure 13 As shown, the electronic detection device 240 in this example includes a substrate 502 on which a plurality of sensor units 503 are disposed, the plurality of sensor units 503 surrounding a corresponding beam aperture 504. The substrate 502 is mounted to the upper electrode (remote to sample 208) of the deceleration array objective 501. The sensor units 503 face the sample 208. The sensor units can be positioned such that the sensing surface is located between upstream and downstream of the facing surface of the upper electrode. The sensor unit 503 can be integrated into or associated with the electrode of the objective 501 furthest from the sample 208. This is consistent with... Figure 7 The electronic detection device 240 forms a comparison. Figure 7 The electronic detection device 240 is integrated into or associated with the lower electrode of the array objective. That is, in both embodiments, the sensor unit can be integrated into the objective 501. Figure 7 The sensor unit 503 can be mounted on the electrode of the array objective lens that is furthest from the source or closest to the sample, but is not necessarily integrated with that electrode. Figure 13 Two-electrode objectives are described, but it should be understood that any other type of objective, such as a three-electrode lens, may also be used.

[0144] In this example, the electron detection device 240 is positioned as the electrode furthest from the source from the objective lens 501, in other words, far from the upstream electrode of the objective lens 501. In this location, the electrodes in the objective lens 501 are closer to the sample or downstream of the electron detection device 240. Therefore, secondary electrons emitted by the sample 208 are accelerated by the downstream positioning electrode array of the objective lens 501, for example, to many kV (approximately 28.5 kV). During operation, the substrate supporting the sensor unit 503 can be maintained at the same potential difference as the upper electrode. Therefore, the sensor unit 503 can include, for example, a PIN detector and / or a scintillator. This has the advantage that there are no significant additional noise sources due to the large initial amplification of the signal by the PIN detector and scintillator. Another advantage of this arrangement is easier access to the electron detection device 240, for example, for making power and signal connections or for maintenance during use. A sensor unit with a trapping electrode could be used in this location, but this would result in poorer performance.

[0145] A PIN detector comprises a reverse-biased PIN diode and has an intrinsic (very lightly doped) semiconductor region sandwiched between a p-doped region and an n-doped region. Secondary electrons incident on the intrinsic semiconductor region generate electron-hole pairs and allow current to flow, generating a detection signal.

[0146] A scintillator is a material that emits light when electrons are incident on it. A detection signal is generated by imaging the scintillator using a camera or other imaging device.

[0147] To accurately image the secondary electrode on sensor unit 503, a relatively large potential difference is desired between the final electrode and sample 208. For example, the upper electrode of the objective lens could be approximately 30 kV, the lower electrode approximately 3.5 kV, and sample 208 approximately 2.5 kV. A large potential difference between the lower electrode and sample 208 can increase aberrations of the objective lens on the primary beam, but appropriate trade-offs can be chosen.

[0148] The precise dimensions of one embodiment can be determined on a case-by-case basis. The diameter of the beam aperture 504 can be in the range of about 5 to 20 μm, for example, about 10 μm. The width of the slit in the electrode can be in the range of 50 to 200 μm, for example, about 100 μm. The distance between the beam aperture and the electrode slit can be in the range of 100 to 200 μm, for example, about 150 μm. The gap between the upper and lower electrodes can be in the range of about 1 to 1.5 mm, for example, about 1.2 mm. The depth of the lower electrode can be in the range of about 0.3 to 0.6 mm, for example, about 0.48 mm. The working distance between the lower electrode and the sample 208 can be in the range of about 0.2 to 0.5 mm, for example, about 0.37 mm. It is desirable that the electric field strength between the lower electrode and the sample 208 is not greater than about 2.7 kV / mm to avoid or reduce damage to the sample 208. The electric field in the gap between the upper and lower electrodes can be larger, for example, exceeding 20 kV / mm.

[0149] The beam aperture 504 associated with the sensor unit has a smaller diameter than the electrode array to increase the surface area of ​​the sensor unit that can be used to capture electrons emitted from the sample. However, the size of the beam aperture diameter is chosen such that it allows sub-beams to pass through; that is, the beam aperture is not beam-limiting. The beam aperture is designed to allow sub-beams to pass through without shaping its cross-section. The same description applies to... Figures 4 to 7 The sensor unit 402 of the illustrated embodiment is associated with a beam aperture 406.

[0150] In one embodiment, a single sensor element (e.g., a PIN detector) surrounds each aperture. The single sensor element may have a circular perimeter and / or outer diameter. The sensor element may have a region extending between the aperture and the perimeter of the sensor element. Sensor elements 503 may be arranged in a rectangular or hexagonal array. In another embodiment, multiple sensor elements (e.g., smaller PIN detectors) are disposed around each aperture. The multiple sensor elements may together have a circular perimeter and / or diameter. The multiple sensor elements may together have a region extending between the aperture and the perimeters of the multiple sensor elements. The multiple sensor elements may be arranged in a rectangular or hexagonal array. Signals generated from electrons captured by the sensor elements surrounding an aperture may be combined into a single signal or used to generate independent signals. Sensor elements may be radially divided. Sensor elements may form multiple concentric rings or loops. Sensor elements may be angularly divided. Sensor elements may form multiple fan-shaped pieces or segments. These segments may have similar angular dimensions and / or similar areas. Sensor elements may be radially and angularly divided or in any other convenient manner. The surface of the sensor unit (optionally its sensor element) can substantially cover the surface of the substrate supporting the sensor unit.

[0151] Figure 15 This is a schematic diagram of the evaluation tool. Parts common to the previous embodiments are indicated by the same reference numerals and will not be described further below. Differences will be described below.

[0152] Each focusing lens in array 1231 guides electrons into corresponding sub-beams 211, 212, 213, which are focused at a corresponding intermediate focal point 1233. A deflector 235 is positioned at the intermediate focal point 1233.

[0153] Below deflector 235 (i.e., downstream of or further from source 201), there is a control lens array 250, which includes control lenses for each sub-bundle 211, 21, 213. The control lens array 250 may include at least two (e.g., three) plate electrode arrays connected to the respective potential sources. The function of the control lens array 250 is to optimize the beam aperture angle and / or control the beam energy delivered to objectives 234 relative to the beam magnification, each objective guiding the corresponding sub-bundle 211, 212, 213 onto sample 208. The control lenses pre-focus the sub-bundles (e.g., apply a focusing action to the sub-bundles before they reach objective array 501). Pre-focusing can reduce sub-bundle divergence or increase sub-bundle convergence. The control lens array and objective array operate together to provide a combined focal length. Combined operation without intermediate focal points reduces the risk of aberrations. Note that references to magnification and aperture angle are intended to refer to variations of the same parameters. In an ideal arrangement, the product of the reduction ratio and the corresponding aperture angle is constant within a certain numerical range. However, the aperture angle may be affected by the aperture size used. (It should be noted that in...) Figure 15 In the arrangement shown, the adjustment to the magnification results in a similar adjustment to the aperture angle, because the beam remains consistent along the beam path.

[0154] In addition to objective array 501, the provision of control lens array 250 provides additional degrees of freedom for controlling the properties of the sub-beams, as described in EP application No. 20196716.3 filed September 17, 2020, the portion relating to the use and control of the control lenses of which is incorporated herein by reference. This additional degree of freedom is provided even when the control lens array 250 and objective array 501 are configured to be relatively close together (e.g., such that no intermediate focus is formed between the control lens array 250 and objective array 501). If two electrodes are present, the magnification and landing energy are controlled together. If three or more electrodes are present, the magnification and landing energy can be controlled independently. Therefore, the control lenses can be configured to adjust the magnification and / or beam opening angle of the respective sub-beams (e.g., by applying appropriate corresponding potentials to the electrodes of the control lenses and objectives using a power supply). This optimization can be achieved by having an excessively negative impact on the number of objectives without excessively worsening the aberrations of the objectives (e.g., without increasing the intensity of the objectives).

[0155] Optionally, an array of scanning deflectors 260 is provided between the array of control lens array 250 and the array of objectives 234. The array of scanning deflectors 260 includes scanning deflectors for each sub-bundle 211, 212, 213. Each scanning deflector is configured to deflect the corresponding sub-bundle 211, 212, 213 in one or both directions to scan the sub-bundle across sample 208 in one or both directions.

[0156] An electron detection device 1240 is disposed between the objective lens 234 and the sample 208 to detect secondary and / or backscattered electrons emitted from the sample 208. An exemplary configuration of the electron detection system is described below.

[0157] Figure 15 The system is configured to control the landing energy of electrons on a sample by varying the potentials of electrodes applied to a control lens and an objective lens. The control lens and objective lens work together and may be referred to as an objective lens assembly. The landing energy can be selected based on the properties of the sample being evaluated to increase the emission and detection of secondary electrons. The controller can be configured to control the landing energy to any desired value within a predetermined range or a desired value among a plurality of predetermined values. In one embodiment, the landing energy can be controlled to a desired value in the range of 1000 eV to 5000 eV.

[0158] The desired landing energy is primarily altered by controlling the energy of electrons leaving the control lens. The potential difference within the objective lens is preferably kept constant during this change, ensuring the electric field within the objective lens remains as high as possible. Furthermore, the potential applied to the control lens can be used to optimize the beam opening angle and magnification. The control lens can also be called a refocusing lens because it corrects the focusing position based on changes in landing energy. The use of an array of control lenses allows the objective lens array to operate at its optimal electric field strength.

[0159] In some embodiments, the charged particle evaluation tool further includes one or more aberration correctors, which, as described above, reduce one or more aberrations in the sub-bundle.

[0160] In one embodiment, the aberration corrector is positioned at or directly adjacent to the intermediate focal point (or intermediate image plane) as described above.

[0161] In some embodiments, the detector 1240 of the objective lens assembly includes a detector array downstream of at least one electrode of the objective lens array 501. In one embodiment, the detector 1240 is adjacent to and / or integrated with the objective lens array 501. For example, the detector array can be implemented by integrating a CMOS chip detector into the bottom electrode of the objective lens array.

[0162] exist Figure 15In a variation of the embodiment, the focusing lens array 1231 and collimator 235 are omitted, as disclosed in European Patent Application No. 20196714.8 filed on September 17, 2020, which is incorporated by reference at least in the disclosure of this electro-optical structure. This arrangement may feature a source 201, a collimator (which may be a macroscopic collimator lens or a collimator lens array), a scanning deflector (which may be a macroscopic scanning deflector or a scanning deflector array), a control lens, an objective lens array, and a detector array. The arrangement is characterized by a beamforming limiter (or beamforming limit array), and may also feature an upper beam limiter. The source 201 emits electrons toward the upper beam limiter, which defines an array of beam-limiting apertures. The upper beam limiter may be referred to as an upper beam-limiting aperture array or an upper beam-limiting aperture array. The upper beam limiter may include a plate (which may be plate-like) having multiple apertures. The upper beam limiter forms sub-beams from the charged particle beam emitted by the source 201. The upper beam limiter can be associated with the control lens array and can form the upstream electrode of the control lens array. Beam portions other than those contributing to sub-beam formation can be blocked (e.g., absorbed) by the upper beam limiter to avoid interfering with downstream sub-beams. A collimator array (e.g., formed using MEMS fabrication techniques) collimates the individual sub-beams and can guide them to the control lenses. In this variant, optionally, the upper beam limiter, collimator element array, control lens 250, scan deflector array 260, objective lens 234, beamforming limiter, and detector module 1240 can all be formed using MEMS fabrication techniques.

[0163] The beamforming limiter is associated with the objective lens and shapes the sub-beam downstream of the control lens. A scanning deflector scans the sub-beam defined upstream of the beamforming limiter. The beamforming limiter shapes the sub-beam incident on the sample surface. Using a beamforming limiter can reduce (if not minimize) aberrations caused by the control lens. When the beamforming limiter is downstream of the control lens array, the aperture in the beamforming limiter adjusts the beam current along the beam path. Therefore, the control lens's control of magnification operates differently with respect to the aperture angle. That is, the aperture in the beamforming limiter breaks the direct correspondence between changes in magnification and the aperture angle.

[0164] In tools with variable landing energy (e.g., the reference above) Figure 15In the aforementioned tool, the Z-position of the focal spot (i.e., its position along the beam path) changes with the landing energy. This is primarily because the focal length of the objective lens is approximately equal to four times the landing energy divided by the electrostatic field in the objective. To improve the aberration level of the objective, it is desirable to maintain the electrostatic field as high as possible. Consequently, the focal length is proportional to the landing energy. If the Z-position of the focal spot is too close to the objective, the electrostatic field in the objective can be reduced, but this results in a loss of resolution. Typically, the sample is moved in the Z direction to ensure that the primary beam is correctly focused onto the wafer. In one arrangement, for a change in landing energy between 500V and 5kV, the Z-position of the focal spot can vary by up to 1 mm, resulting in a substantial change in the measurement signal depending on the distance between the sample and the detector. The relationship between the change in landing energy and the change in the Z-position of the focal spot depends in part on the lens strength of the objective; therefore, in other arrangements, the range of variation in the Z-position of the focal spot can be greater than or less than 1 mm. A linear relationship can exist between the landing energy and the focal length. Within the aforementioned range of landing energies, resolution can be substantially maintained.

[0165] According to one embodiment, it is proposed that the detector's position relative to the sample be maintained even if the sample moves relative to the objective lens due to changes in the focusing position (e.g., due to changes in landing energy). For example, the distance between the sample and the detector is maintained in the range of about 50 to 100 μm. In one embodiment, the distance between the objective lens and the sample can be about 250 μm or greater. However, there are lower limits to the proximity at which the objective lens can be positioned relative to the sample and to the proximity of the sub-beam's focal point to the objective lens. In this case, there is a risk that the objective electrodes may need to be too thin to be easily manufactured. The detector used with this arrangement may need to be too thin to be easily manufactured. The desired distance between the sample and the detector can depend on the detector size (particularly the electrode diameter) and / or the detector pitch. All other things being equal, a larger detector and / or a larger detector pitch can allow for a greater distance between the sample and the detector. Therefore, embodiments of the invention can maintain high secondary electron detection for a given beam pitch and detector diameter.

[0166] Two methods are proposed for maintaining a constant distance between the sample and the detector. For example... Figure 16 As shown, detector module 240 is connected to actuator system 245, which is configured to position detector module 240 in a direction parallel to the propagation direction of the electron beam, i.e., perpendicular to the surface of the sample. Figure 16In the diagram, A, B, and C illustrate arrangements of the detector at different longitudinal positions. The actuation system 245 can be connected to the overall control system 50 to maintain the detection module 245 at a constant distance from the sample. This is even when the sample is moved to position its surface at a focal position that changes, for example, due to a change in the landing energy of the electron beam. It is not necessary to maintain the distance between the detector module 240 and the sample 208 precisely constant. Instead, reducing the variation in distance to an acceptable level is sufficient. The actuation system 245 can include various types of actuators, such as piezoelectric actuators and Lorentz actuators. One actuator may be sufficient to position all sensor units of the detector module, or multiple actuators may be used, each positioning a group of sensor units. Each sensor unit may also have one or more actuators. Since the detector can be located in an array on the substrate, the actuator arrangement can actuate the substrate. It is desirable that the actuators can reposition the detector module within seconds or less.

[0167] In addition to positioning the detector in Z, the actuator system 245 can be configured to position the detector in other degrees of freedom, such as Rx and Ry. However, providing actuation with additional degrees of freedom may undesirably increase complexity.

[0168] In another approach, the detector is replaceable. Figure 17 In the illustrated embodiment, two or more (e.g., three, four, or five) detector modules are interchangeable. Each interchangeable detector module 240a, 240b, 240c is configured such that the charged particle receiving surface of its sensor unit is positioned at a different longitudinal location relative to objective 401. For example, each detector module 240a, 240b, 240c may be formed on a substrate of different sizes (e.g., thicknesses). Alternatively or additionally, spacers of different thicknesses may be provided. Such spacers may be used to space the detectors relative to the objective array. Detector modules may be interchangeable individually or in combination with other elements such as objective assemblies, objective arrays, beamforming limiters, upper limit arrays, collimator arrays, scanning deflector arrays, and / or control lens arrays. Different electro-optical components may have their own designated modules. They may be included in the same module along with other electro-optical components, such that the number of modules is less than the number of interchangeable electro-optical components. Alternatively, all interchangeable electro-optical components (preferably MEMS elements) of, for example, the objective assembly may be located in an interchangeable module. In one arrangement, the module may include, for example, actuators for actuating the detector array relative to other electro-optical components in the module. Spacers used to space the electro-optical components may be interchangeable. Spacers may be incorporated between the electro-optical components in a module having multiple electronic components.

[0169] An automated interchange mechanism is desired, enabling modules such as detector modules to be exchanged between operable and inoperable positions without opening the tool, for example, between evaluations of consecutive or batch samples. Alternatively, modules such as detector modules can be manually interchangeable, such as field-replaceable modules. As described in U.S. Application Serial No. 63 / 037,481, filed June 10, 2020, which is incorporated herein by reference, a field-replaceable module can be removed and replaced with the same or different module while maintaining a vacuum in which the electro-optical tool 40 is located, at least in respect of implementing the features of the replaceable module. Only portions of the column corresponding to the module to be replaced are vented for the module to be removed and returned or replaced. Although this is less desirable than an automated interchange mechanism due to the increased downtime caused by opening the tool, it remains advantageous in the case of long-term operation of measurements under the same beam setup to be performed. If an automated interchange device is provided, the exchange of modules may take on the order of minutes, while manual exchange may take on the order of hours. Actuating electro-optical components (such as detectors) can be faster than automatic or manual module swapping, taking only a few seconds. The longitudinal position of the detector module can also be controlled by using interchangeable spacers, which can be interchanged through automatic or manual arrangements as described with respect to electro-optical modules. Interchangeable spacers can be incorporated into interchangeable modules.

[0170] The evaluation tool according to embodiments of the present invention can be a tool for qualitative evaluation of a sample (e.g., pass / fail), a tool for quantitative measurement of a sample (e.g., size of features), or a tool for generating an image of the sample's topography. Examples of evaluation tools are inspection tools and measurement tools.

[0171] The following clauses are exemplary embodiments of the present invention:

[0172] Clause 1: A charged particle evaluation tool comprising: an objective lens configured to project a plurality of charged particle beams onto a sample, the objective lens having a sample-facing surface defining a plurality of beam apertures through which a respective charged particle beam is emitted toward the sample; and a plurality of trapping electrodes adjacent to a respective beam aperture and configured to trap charged particles emitted from the sample.

[0173] Clause 2: The tool described in Clause 1, wherein each capture electrode is configured to substantially surround the corresponding beam aperture.

[0174] Clause 3: The tool described in Clause 1 or 2, wherein the capture electrode is configured to substantially cover the sample-facing surface.

[0175] Clause 4: The tool described in Clause 1 or 2, wherein the capture electrode has a circular outer periphery.

[0176] Clause 5: The tool according to any one of the preceding clauses further includes a substrate mounted on the sample-facing surface of the objective lens, and a capture electrode is formed on the substrate.

[0177] Clause 6: The tool described in Clause 5 further includes a control circuit system formed in the substrate.

[0178] Clause 7: The tool described in Clause 6, wherein the control circuitry system includes one or more of the following: an amplifier, such as a transimpedance amplifier; an analog-to-digital converter; a data multiplexer; a readout.

[0179] Clause 8: The tool described in Clause 7, wherein the control circuitry includes an amplifier for each capture electrode.

[0180] Clause 9: The tool according to any one of Clauses 5 to 8 further includes a conductive trace disposed on the other side of the substrate to the capture electrode.

[0181] Clause 10: The tool according to any one of Clauses 5 to 9 further includes a plurality of vias that pass through the substrate.

[0182] Clause 11: The tool according to any one of Clauses 5 to 10, wherein the substrate is formed of silicon.

[0183] Clause 12: The tool according to any one of the preceding clauses, wherein the capture electrode is formed by a CMOS process.

[0184] Clause 13: The tool according to any one of the preceding clauses, wherein each capture electrode comprises a plurality of electrode elements.

[0185] Clause 14: A method of manufacturing an evaluation tool, the method comprising: forming a plurality of trapping electrodes on a substrate and forming a plurality of apertures in the substrate; and attaching the substrate to an objective lens configured to project a plurality of charged particle beams onto a sample such that the charged particle beams can be emitted through the apertures.

[0186] Clause 15: The method of Clause 14, wherein the aperture is formed by etching through the substrate.

[0187] Clause 16: An inspection method comprising: emitting a plurality of charged particle beams radially through a plurality of beam apertures onto a sample; and using a plurality of trapping electrodes to trap the charged particles emitted by the sample in response to the charged particle beams, the plurality of trapping electrodes being configured adjacent to a corresponding beam aperture in the beam aperture.

[0188] Clause 17: A multi-beam electron optical system comprising a final electron optical element in a multi-beam path of the multi-beam electron optical system, the final electron optical element comprising: a multi-manipulator array, wherein each array element is configured to manipulate at least one electron beam in the multi-beam path; and a detector configured and oriented to detect electrons emitted from a sample in the multi-beam path, wherein the detector comprises a plurality of electrodes integrated into the multi-manipulator array and at least one electrode associated with each array element.

[0189] Clause 18: A final electro-optical element for a multi-charged beam projection system configured to project a plurality of charged particle beams onto a sample, the final electro-optical element comprising: an objective lens having a sample-facing surface defining a plurality of beam apertures through which a respective charged particle beam is emitted toward the sample; and a plurality of trapping electrodes adjacent to the respective beam apertures and configured to trap the charged particles emitted from the sample.

[0190] Clause 19: A charged particle evaluation tool comprising: an objective lens configured to project a plurality of charged particle beams onto a sample, the objective lens defining a plurality of beam apertures, wherein a respective charged particle beam is capable of propagating toward the sample through the beam apertures; and a plurality of sensor units adjacent to a respective beam aperture and configured to capture charged particles emitted from the sample.

[0191] Clause 20: The tool described in Clause 19, wherein each sensor unit is configured to substantially surround the corresponding beam aperture.

[0192] Clause 21: The tool described in Clause 19 or 20, wherein the sensor unit has a circular outer periphery.

[0193] Clause 22: The tool according to any one of the preceding clauses further includes a substrate disposed on the downstream-facing surface of the objective lens, and the sensor unit is formed on the substrate.

[0194] Clause 23: The tool described in Clause 22, wherein the sensor unit is configured to substantially occupy the sample-facing surface.

[0195] Clause 24: The tool described in Clause 22 or 23, wherein the sensor unit is a capture electrode.

[0196] Clause 25: The tool according to any one of the preceding clauses further includes a substrate disposed on the upstream-facing surface of the objective lens, and a sensor unit is formed on the substrate, preferably configured to face downstream.

[0197] Clause 26: The tool described in Clause 25, wherein the sensor unit is selected from a combination of a PIN detector and a scintillator.

[0198] Clause 27: The tool according to any one of Clauses 22 to 26 further includes a control circuit system formed in the substrate.

[0199] Clause 28: The tool described in Clause 27, wherein the control circuitry system includes one or more of the following: an amplifier, such as a transimpedance amplifier; an analog-to-digital converter; a data multiplexer; and a readout.

[0200] Clause 29: The tool described in Clause 28, wherein the control circuitry includes an amplifier for each sensor unit.

[0201] Clause 30: The tool according to any one of Clauses 22 to 29 further includes a conductive trace disposed on the other side of the substrate to the sensor unit.

[0202] Clause 31: The tool pursuant to any one of Clauses 22 to 30 further includes a via through the substrate.

[0203] Clause 32: The tool according to any one of Clauses 22 to 31, wherein the substrate is formed of silicon.

[0204] Clause 33: The tool according to any one of the preceding clauses, wherein the sensor unit is formed by a CMOS process.

[0205] Clause 34: The tool according to any one of the preceding clauses, wherein each sensor unit comprises a plurality of sensor elements.

[0206] Clause 35: An instrument pursuant to any of the preceding clauses, wherein the objective lens is an electrostatic lens.

[0207] Clause 36: The tool according to any one of the preceding clauses further includes an actuation system configured to adjust the position of the sensor unit in a direction parallel to the propagation direction of the electron beam.

[0208] Clause 37: The tool according to any one of Clauses 19 to 36 comprises: a first sensor unit array; a second sensor unit array; and an interchangeable mechanism configured to selectively position either the first sensor unit array or the second sensor unit array at a downstream-facing surface of the objective lens; wherein the first sensor unit array and the second sensor unit array are configured such that when the respective array is positioned at the downstream-facing surface, the sensor units of the first sensor unit array are positioned at a different distance from the objective lens compared to the sensor units of the second sensor unit array.

[0209] Clause 38: A charged particle evaluation tool comprising: an objective lens configured to project a plurality of charged particle beams onto a sample through a plurality of beam apertures defined within the objective lens; and a sensor array including sensor units adjacent to respective beam apertures and configured to capture charged particles emitted from the sample; wherein the sensor array is configured to be adjustable between positions along the beam path of the charged particle beams.

[0210] Clause 39: The tool described in Clause 38, wherein the sensor array is configured such that actuation of the sensor array along the beam path is adjustable.

[0211] Clause 40: The tool described in Clause 39 also includes an actuator configured to actuate the sensor array along the beam path.

[0212] Clause 41: A charged particle evaluation tool comprising: an objective lens configured to project a plurality of charged particle beams onto a sample through a plurality of beam apertures defined within the objective lens; and a sensor array including sensor units adjacent to respective beam apertures and configured to capture charged particles emitted from the sample; wherein the sensor array is configured to be actuable along the beam path of the charged particle beams.

[0213] Clause 42: Any tool according to any one of Clauses 36 to 41 further includes a beam energy control system configured to control the landing energy of the electron beam on the sample.

[0214] Clause 43: The tool described in Clauses 36 to 42 further includes a control lens array upstream of the objective lens array.

[0215] Clause 44: The tool according to Clause 43, wherein the objective array and the control lens array include at least electrodes configured in operation to: cause the objective to focus a beam of charged particles onto the sample, and control the lenses to adjust the beam opening angle and / or reduce the beam.

[0216] Clause 45: A multi-beam charged particle optical column configured to direct a multi-beam light toward a sample, the multi-beam light being generated downstream from a source, the column comprising: a detector configured to capture charged particles emitted from the sample, wherein the detector is actuable along the beam path.

[0217] Clause 46: A multi-beam charged particle optical array as described in Clause 45, wherein the detector comprises a sensor array, each sensor being assigned to a corresponding sub-beam in the multi-beam array.

[0218] Clause 47: A multi-beam charged particle optical array as described in Clause 45 or 46, wherein the array includes a beam-limiting aperture array configured to generate multiple beams derived from a source beam.

[0219] Clause 48: A multi-beam charged particle optical array as described in Clause 47, wherein the detector is downstream of a beam-confining aperture array.

[0220] Clause 49: A multi-beam charged particle optical array according to any one of Clauses 45 to 48, wherein the detector is integrated into an objective assembly including the objective lens.

[0221] Clause 50: A method of manufacturing an evaluation tool, the method comprising: forming a plurality of sensor units on a substrate and forming a plurality of apertures in the substrate; and attaching the substrate to an objective lens configured to project a plurality of beams of charged particles onto a sample such that the beams of charged particles can be emitted through the apertures.

[0222] Clause 51: The method according to Clause 50, wherein the aperture is formed by etching through the substrate.

[0223] Clause 52: An inspection method comprising: emitting a plurality of charged particle beams radially through a plurality of beam apertures onto a sample; and using a plurality of sensor units to capture the charged particles emitted by the sample in response to the charged particle beams, the plurality of sensor units being configured to be adjacent to a corresponding beam aperture in the beam aperture.

[0224] Clause 53: The method described in Clause 52 further includes: changing the position of the sensor unit along the path of the charged particle beam.

[0225] Clause 54: A multi-beam electron optical system comprising a final electron optical element in a multi-beam path of the multi-beam electron optical system, the final electron optical element comprising: a multi-manipulator array, wherein each array element is configured to manipulate at least one electron beam in the multi-beam path; and a detector configured and oriented to detect electrons emitted from a sample in the multi-beam path, wherein the detector comprises a plurality of sensor units integrated into the multi-manipulator array and at least one sensor unit associated with each array element.

[0226] Clause 55: A final electro-optical element for a multi-charged beam projection system configured to project a plurality of charged particle beams onto a sample, the final electro-optical element comprising: an objective lens having a sample-facing surface defining a plurality of beam apertures through which a respective charged particle beam propagates toward the sample; and a plurality of sensor units adjacent to the respective beam apertures and configured to capture charged particles emitted from the sample.

[0227] The above description is intended to illustrate and not limit. Therefore, it will be apparent to those skilled in the art that modifications as described can be made without departing from the scope of the claims set forth below.

Claims

1. A charged particle evaluation tool, comprising: An objective array is configured to project multiple beams of charged particles onto a sample, the objective array defining multiple beam apertures, wherein corresponding charged particle beams of the charged particle beams are able to propagate toward the sample through the multiple beam apertures, wherein the objective array is electrostatic; as well as Multiple sensor units surround a corresponding beam aperture in the beam aperture and are configured to capture charged particles emitted from the sample, wherein the multiple sensor units include multiple capture electrodes, and each capture electrode surrounds a corresponding beam aperture of the objective array.

2. The tool of claim 1, wherein the sensor unit has a circular outer periphery, and wherein the sensor unit has a region extending between the aperture and the periphery of the sensor unit.

3. The tool according to claim 1 or 2 further includes a substrate disposed on the downstream-facing surface of the objective lens array, on which the sensor unit is formed.

4. The tool of claim 3, wherein the sensor unit is configured to cover the sample-facing surface.

5. The tool according to claim 3, wherein the sensor unit is a capture electrode.

6. The tool according to claim 1 or 2 further includes a substrate disposed on the upstream-facing surface of the objective lens array, and the sensor unit is formed on the substrate.

7. The tool according to any one of claims 1, 2, 4 or 5, wherein the plurality of sensor units are integrated into the objective lens.

8. The tool of claim 3 further includes a control circuit system formed in the substrate.

9. The tool of claim 8, wherein the control circuit system comprises one or more of the following: Amplifier; Analog-to-digital converter; Data multiplexer; Read the door.

10. The tool of claim 9, wherein the control circuitry includes an amplifier for each sensor unit.

11. The tool of claim 3 further includes a conductive trace disposed on the other side of the substrate to the sensor unit.

12. The tool of claim 3 further includes a via through the substrate.

13. The tool of claim 3, wherein the substrate is formed of silicon.

14. The tool of claim 3, wherein the sensor unit is formed using a CMOS process.

15. The tool according to any one of claims 1, 2, 4, 5 and 8-14, wherein each sensor unit comprises a plurality of sensor elements.

16. The tool of claim 15, wherein the plurality of sensor elements radially divide each sensor unit.

17. The tool of claim 15, wherein the plurality of sensor elements are angularly divided into each sensor unit.

18. The tool of claim 15, wherein the sensor elements of the sensor unit together have a region extending between the aperture and the periphery of the plurality of sensor units.

19. The tool according to any one of claims 1, 2, 4, 5, 8-14, 16 and 18, wherein the beam aperture can be arranged in a hexagonal array.

20. An inspection method, comprising: Multiple beams of charged particles are emitted radially from the sample through multiple beam apertures of an objective lens array, wherein the objective lens array is electrostatic; as well as Charged particles emitted by the sample in response to the beam of charged particles are captured using a plurality of sensor units configured to surround a corresponding beam aperture in the beam aperture, wherein the plurality of sensor units include a plurality of capture electrodes, and each capture electrode surrounds a corresponding beam aperture of the objective array.

21. The inspection method according to claim 20, further comprising: The sensor unit generates a detection signal.

22. A charged particle evaluation tool, comprising: An objective array is configured to project multiple beams of charged particles onto a sample, the objective array defining multiple beam apertures, wherein corresponding charged particle beams of the charged particle beams can propagate toward the sample through the multiple beam apertures; as well as Multiple sensor units surround a corresponding beam aperture in the beam aperture and are configured to capture charged particles emitted from the sample, wherein the objective array is an electrostatic array objective, and wherein the multiple sensor units include multiple capture electrodes, and each capture electrode surrounds a corresponding beam aperture of the objective array.

23. The charged particle evaluation tool of claim 22, wherein the objective array has at least two plates, each plate having a plurality of apertures.

24. The charged particle evaluation tool of claim 23, wherein the sensor unit has a circular outer periphery and the sensor unit has a region extending between the aperture and the periphery of the sensor unit.

25. A multi-beam charged particle optical array configured to direct multiple beams toward a sample, the multiple beams being generated downstream from a source, the array comprising: An objective lens is configured to project a plurality of charged particle beams onto a sample, the objective lens defining a plurality of beam apertures, wherein a corresponding charged particle beam in the charged particle beams is able to propagate toward the sample through the plurality of beam apertures, wherein the objective lens is electrostatic; A detector is configured to capture charged particles emitted from the sample, wherein the detector is actuable along the path of the multi-beam, wherein the detector includes a capturing electrode, and each capturing electrode surrounds a corresponding beam aperture of the objective lens.

26. The multi-beam charged particle optical array of claim 25, wherein the array comprises a beam-limiting aperture array configured to generate the multi-beams derived from the source beam.

27. The multi-beam charged particle optical array of claim 26, wherein the detector is downstream of the beam-confining aperture array.

28. The multi-beam charged particle optical array according to any one of claims 25 to 27, further comprising: The detector comprises a sensor array, with each sensor assigned to a corresponding sub-beam of the multi-beam.

29. The multi-beam charged particle optical array of claim 28, wherein each sensor unit is configured to surround a corresponding beam aperture.

30. The multi-beam charged particle optical array according to claim 29, wherein the sensor unit has a circular outer periphery.

31. The multi-beam charged particle optical array of claim 29, wherein the sensor unit is integrated into an objective lens assembly including the objective lens.

32. The multi-beam charged particle optical array of claim 31 further includes a substrate disposed on the downstream-facing surface of the objective lens, and the sensor unit is formed on the substrate.

33. The multi-beam charged particle optical array of claim 32, wherein the sensor unit is configured to cover the sample-facing surface.

34. The multi-beam charged particle optical array according to claim 32 or 33, wherein the sensor unit is a capture electrode.

35. The multi-beam charged particle optical array according to any one of claims 32 to 33, further comprising a control circuit system formed in the substrate.

36. The multi-beam charged particle optical array according to any one of claims 32 to 33, further comprising a via through the substrate.

37. The multi-beam charged particle optical array according to any one of claims 31 to 33, wherein the objective assembly includes a beam energy control system configured to control the landing energy of the charged particle beams on the sample.

38. The multi-beam charged particle optical array according to any one of claims 31 to 33, wherein the objective lens assembly includes a control lens array upstream of the objective lens.

39. The multi-beam charged particle optical array according to any one of claims 29 to 33, further comprising a substrate disposed on the upstream-facing surface of the objective lens, and the sensor unit being formed on the substrate.

40. A charged particle evaluation tool comprising a multi-beam charged particle optical array according to any one of claims 26 to 29, the multi-beam charged particle optical array further comprising an actuator configured to actuate the detector along the path of the multi-beam.

41. An inspection method, comprising: Multiple beams of charged particles are emitted radially from the sample through multiple beam apertures of an objective lens, wherein the objective lens is electrostatic; as well as A detector is used to capture charged particles emitted by the sample in response to the beam of charged particles, wherein the detector includes capturing electrodes, each capturing electrode surrounding a corresponding beam aperture of the objective lens; and The position of the detector is changed along the path of the multi-beam.

42. The method of claim 41, further comprising: The position of the detector is changed along the path of the charged particle beam.

43. A charged particle evaluation tool, comprising: An objective lens is configured to project a plurality of charged particle beams onto a sample through a plurality of beam apertures defined in the objective lens, wherein the objective lens is electrostatic; as well as A sensor array, comprising sensor units adjacent to a corresponding beam aperture, and configured to capture charged particles emitted from the sample, wherein the sensor array comprises a plurality of capturing electrodes, and each capturing electrode surrounds a corresponding beam aperture of the objective lens; The sensor array is configured to be adjustable between positions along the beam path of the charged particle beam.

44. The tool of claim 43, wherein the sensor array is configured to be adjustable by actuation of the sensor array along the beam path.

45. The tool of claim 44, further comprising an actuator configured to actuate the sensor array along the beam path.

46. ​​A charged particle evaluation tool, comprising: An objective lens is configured to project multiple beams of charged particles onto a sample through multiple beam apertures defined in the objective lens, wherein the objective lens is electrostatic; as well as A sensor array comprising sensor units adjacent to a corresponding beam aperture and configured to capture charged particles emitted from the sample, wherein the sensor array includes a plurality of capturing electrodes, and each capturing electrode surrounds a corresponding beam aperture of the objective lens; The sensor array is configured to be actuable along the beam path of the charged particle beam.

47. A method for manufacturing an evaluation tool, the method comprising: Multiple sensor units are formed on a substrate, and multiple apertures are formed in the substrate, wherein the multiple sensor units include multiple trapping electrodes, and each trapping electrode surrounds a corresponding beam aperture of the objective lens; as well as The substrate is attached to an objective lens configured to project a plurality of charged particle beams onto the sample, such that the charged particle beams can be emitted through the aperture, wherein the objective lens is electrostatic.

48. The method of claim 47, wherein the aperture is formed by etching through the substrate.

49. A multi-beam electro-optical system, the multi-beam electro-optical system including a final electro-optical element in a multi-beam path of the multi-beam electro-optical system, the final electro-optical element comprising: A multi-manipulator array, wherein each array element is configured to manipulate at least one electron beam in the multi-beam path; An objective array is configured to project multiple beams of charged particles onto a sample, the objective array defining multiple beam apertures, wherein corresponding charged particle beams of the charged particle beams are able to propagate toward the sample through the multiple beam apertures, wherein the objective array is electrostatic; as well as A detector is configured and oriented to detect electrons emitted from a sample and located in the multi-beam path, wherein the detector includes a trapping electrode and each trapping electrode surrounds a corresponding beam aperture.

50. A final electron-optical element for a multi-band beam projection system configured to project a plurality of charged particle beams onto a sample, the final electron-optical element comprising: An objective lens having a sample-facing surface defining multiple beam apertures through which a corresponding charged particle beam in the charged particle beam can propagate toward the sample, wherein the objective lens is electrostatic; as well as A plurality of sensor units, adjacent to a corresponding beam aperture in the beam aperture and configured to capture charged particles emitted from the sample, wherein the plurality of sensor units include a plurality of capturing electrodes, and each capturing electrode surrounds a corresponding beam aperture of the objective lens.

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