Charged particle optical device

Abstract

A charged particle optical apparatus for evaluating a sample at an evaluation location, the charged particle optical apparatus comprising: an evaluation charged particle optical device configured to project an evaluation charged particle beam along an evaluation beam path towards an evaluation location, the evaluation charged particle beam for evaluating the sample at the evaluation location; a pre-charged particle optical device configured to project a pre-charged particle beam along a pre-beam path, the pre-charged particle beam for preparing a sample for evaluation; and a light source configured to project a light beam toward the irradiation position; wherein a positional relationship between the irradiation position and the evaluation charged particle optical device is different from a positional relationship between the evaluation position and the evaluation charged particle optical device.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to EP application number 22185276.7 filed on July 15, 2022 and EP application number 22201416.9 filed on October 13, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003]

[0013] Embodiments provided herein generally relate to charged particle optical devices and methods for evaluating samples. Background Art

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

[0005] Pattern inspection tools with charged particle beams have been used to inspect objects, such as detecting pattern defects. These tools typically use electron microscopy techniques, such as scanning electron microscopes (SEMs). In an SEM, a primary electron beam of electrons at relatively high energy is targeted at a final deceleration step so as to land on a sample with a relatively low landing energy. The electron beam is focused onto the sample as a probing spot. The interaction between the material structure at the probing spot and the landing electrons from the electron beam causes signal electrons to be emitted from the surface, such as secondary electrons, backscattered electrons, or Auger electrons, which may also be referred to as signal particles. The generated secondary electrons may be emitted from the material structure of the sample. By scanning the primary electron beam as a probing spot on the sample surface, secondary electrons may be emitted across the sample surface. By collecting these emitted secondary electrons from the sample surface, the pattern inspection tool may obtain an image representing the characteristics of the material structure of the sample surface. The intensity of the electron beam, including backscattered electrons and secondary electrons, may vary based on the properties of the internal and external structures of the sample, thereby indicating whether the sample has defects.

[0006] When the primary electron beam scans the sample, due to the large beam current, charge may accumulate on the sample, which may affect the quality of the image. The material structure can be irradiated with light and / or flooded with electrons to improve defect contrast during defect inspection. For example, in order to adjust the accumulated charge on the sample, an advanced charge controller (ACC) module can be used to irradiate a light beam such as a laser beam onto the sample to control the accumulated charge caused by effects such as photoconductivity, photoelectric or thermal effects. The term ACC is used as an abbreviation for beam irradiation in the following description. It should be understood that the term ACC generally refers to irradiation by a light beam. It may be difficult to irradiate the light beam onto the sample. For example, the size of the pattern inspection tool may make it difficult for the light beam to reach the sample. Summary of the invention

[0007] It is an object of the present disclosure to provide embodiments that support increasing the amount of light irradiated onto a sample for evaluation involving improved defect contrast.

[0008] According to a first aspect of the present invention, a charged particle optical device is provided for evaluating a sample at an evaluation position, the charged particle optical device comprising: an evaluation charged particle optical device configured to project an evaluation charged particle beam along an evaluation beam path toward the evaluation position, the evaluation charged particle beam being used to evaluate the sample at the evaluation position; a preparation charged particle optical device configured to project a preparation charged particle beam along the preparation beam path, the preparation charged particle beam being used to prepare the sample for evaluation; and a light source configured to project a light beam toward an irradiation position; wherein the positional relationship between the irradiation position and the evaluation charged particle optical device is different from the positional relationship between the evaluation position and the evaluation charged particle optical device.

[0009] According to a second aspect of the present invention, a charged particle optical device is provided for evaluating a sample at an evaluation position, the charged particle optical device comprising: an evaluation charged particle optical device configured to project an evaluation charged particle beam along an evaluation beam path toward the evaluation position, the evaluation charged particle beam being used to evaluate the sample at the evaluation position; a preparation charged particle optical device configured to project a preparation charged particle beam along a preparation beam path, the preparation beam being used to prepare the sample for evaluation; and a light source configured to project a light beam toward the sample at an irradiation position away from the evaluation position when the sample is positioned away from the evaluation position, desirably when the sample is at the irradiation system.

[0010] According to a third aspect of the present invention, a method for evaluating a sample at an evaluation position is provided, the method comprising: projecting a preliminary charged particle beam along a preliminary beam path using a preliminary charged particle optical device, the preliminary charged particle beam being used to prepare the sample for evaluation; projecting a light beam toward the sample at an irradiation position; and projecting an evaluation charged particle beam along the evaluation beam path toward the sample at the evaluation position using an evaluation charged particle optical device, the evaluation charged particle beam being used to evaluate the sample at the evaluation position; wherein the positional relationship between the irradiation position and the evaluation charged particle optical device is different from the positional relationship between the evaluation position and the evaluation charged particle optical device.

[0011] According to a fourth aspect of the present invention, a method for evaluating a sample at an evaluation position is provided, the method comprising: projecting a preliminary charged particle beam along a preliminary beam path using a preliminary charged particle optical device, the preliminary charged particle beam being used to prepare the sample for evaluation; projecting a light beam toward the sample at an irradiation position; and projecting an evaluation charged particle beam along an evaluation beam path toward the sample at the evaluation position using an evaluation charged particle optical device, the evaluation charged particle beam being used to evaluate the sample at the evaluation position; wherein when the sample is away from the evaluation position, the light beam is projected toward the sample at the irradiation position.

[0012] According to a fifth aspect of the present invention, a method for evaluating a sample at an evaluation position is provided, the method comprising: projecting a preliminary charged particle beam toward the sample to prepare the sample for evaluation; projecting a light beam toward the sample; and projecting an evaluation charged particle beam toward the sample along an evaluation beam path at the evaluation position to evaluate the sample at the evaluation position; wherein the projection of the light beam is before the sample is at the evaluation position.

[0013] According to a sixth aspect of the present invention, a charged particle optical device is provided for evaluating a sample at an evaluation position, the charged particle optical device comprising: an evaluation charged particle optical device configured to project an evaluation charged particle beam along an evaluation beam path toward the evaluation position, the evaluation charged particle beam being used to evaluate the sample at the evaluation position; and a preparation charged particle optical device configured to project a preparation charged particle beam along the preparation beam path, the preparation charged particle beam being used to prepare the sample for evaluation; wherein the evaluation charged particle optical device comprises one or more charged particle optical elements, the charged particle optical elements comprising micro-electromechanical components and / or objective lenses, the objective lenses comprising multiple objective lenses for evaluating different beams of the charged particle beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above and other aspects of the present disclosure will become more apparent through the description of exemplary embodiments with reference to the attached drawings.

[0015] Figure 1is a schematic diagram illustrating an exemplary electron beam inspection apparatus.

[0016] Figure 2 is shown as Figure 1 A schematic diagram of an exemplary multi-beam electron optical apparatus of a portion of an exemplary electron beam inspection apparatus.

[0017] Figure 3 is a schematic diagram of an exemplary multi-beam electron optical setup.

[0018] Figure 4 is a schematic diagram of an exemplary electron optical device including a macro collimator and a macro scan deflector.

[0019] Figure 5 is a schematic diagram of an exemplary multi-beam electron optical device according to an embodiment.

[0020] Figure 6 yes Figure 5 Schematic diagram of a portion of a multibeam electron optical setup.

[0021] Figure 7 is a schematic cross-sectional view of an objective lens array of an electron optical device according to an embodiment.

[0022] Figure 8 yes Figure 7 Bottom view of a variation of the objective lens array.

[0023] Fig. 9 is combined with Figure 7 A magnified cross-sectional view of the detector in the objective lens array.

[0024] Fig.10 is a bottom view of a detector element of the detector.

[0025] Fig.11 is a schematic diagram of an exemplary electro-optical device according to an embodiment.

[0026] Fig.12 is a schematic diagram of an exemplary electro-optical device according to an embodiment.

[0027] Fig.13 is a schematic diagram of an exemplary evaluation electron optical device according to an embodiment.

[0028] The schematic diagrams and views show the components described below. However, the components shown in the figures are not drawn to scale. DETAILED DESCRIPTION

[0029] Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description is made with reference to the accompanying drawings, and unless otherwise indicated, the same reference numerals in different drawings represent the same or similar elements. The implementations set forth in the following description of the exemplary embodiments do not represent all implementations consistent with the present invention. Instead, they are merely examples of devices and methods consistent with various aspects of the present invention as recited in the appended claims.

[0030] The enhanced computing power of electronic devices can be achieved by significantly increasing the packaging density of circuit components (such as transistors, capacitors, diodes, etc.) on IC chips, which reduces the physical size of the device. This is achieved by increasing the resolution, which enables the manufacture of smaller structures. For example, the IC chip of a smartphone (which is the size of a thumbnail and available in 2019 or earlier) may include more than 2 billion transistors, each of which is less than 1 / 1000 the size of a human hair. Not surprisingly, semiconductor IC manufacturing is a complex and time-consuming process with hundreds of individual steps. Even an error in one step has the potential to greatly affect the operation of the final product. In some cases, even a single defect can cause device failure. The goal of the manufacturing process is to increase the overall yield of the process. For example, in order to obtain a 75% yield for a 50-step process (where one step can indicate the number of layers formed on the wafer), each individual step must have a yield greater than 99.4%. If each individual step has a 95% yield, the total process yield will be as low as 7%.

[0031] While high process yields are desired in IC chip manufacturing facilities, it is also essential to maintain high substrate (i.e., wafer) throughput, which is defined as the number of substrates processed per hour. The presence of defects may compromise both high process yields and high substrate throughput. This is especially true if operator intervention is required to review the defects. Therefore, high throughput detection and identification of micron and nanometer-scale defects by inspection systems, such as scanning electron microscopes ("SEMs"), is important to maintaining high yields and low costs.

[0032] The SEM includes a scanning device and a detector device. The scanning device includes an irradiation device, which includes an electron source for generating primary electrons and a projection device for scanning a sample such as a substrate using one or more focused primary electron beams. At least the irradiation device or irradiation system and the projection device or projection system together can be collectively referred to as an electron optical device or device. The primary electrons interact with the sample and generate secondary electrons. The detection device captures the secondary electrons from the sample as the sample is scanned, so that the SEM can create an image of the scanned area of ​​the sample. For high-throughput inspection, some inspection devices use multiple focused primary electron beams, i.e., multiple beams. The component beams in the multiple beams can be referred to as sub-beams or beam waves. Multiple beams can scan different parts of the sample at the same time. Therefore, a multi-beam inspection device can inspect the sample at a much higher speed than a single-beam inspection device.

[0033] The following describes a known implementation of a multi-beam inspection device.

[0034] The drawings are schematic. Therefore, for the sake of clarity, the relative sizes of the components in the drawings are exaggerated. In the following description of the drawings, the same or similar reference numerals refer to the same or similar components or entities, and only the differences with respect to the various embodiments are described. Although the description and drawings refer to electron-optical devices, it is to be understood that the embodiments are not intended to limit the present disclosure to specific charged particles. Therefore, references to electrons throughout this document may be more generally considered to be references to charged particles, which are not necessarily electrons. For example, references to electron-optical devices may be more generally considered to be references to charged particle devices.

[0035] Reference now Figure 1 , Figure 1 is a schematic diagram illustrating an exemplary charged particle beam inspection apparatus 100 . Figure 1 The charged particle beam inspection apparatus 100 includes a main chamber 10, a load lock chamber 20, an electron optical device 40 (also called an electron evaluation device or electron beam system or tool), an equipment front end module (EFEM) 30, and a controller 50. The electron optical device 40 is located in the main chamber 10.

[0036] The EFEM 30 includes a first feed port 30a and a second feed port 30b. The EFEM 30 may include (one or more) additional feed ports. The first feed port 30a and the second feed port 30b may, for example, accommodate a substrate front opening pod (FOUP) containing a substrate to be inspected (e.g., a semiconductor substrate or a substrate made of (one or more) other materials) or a sample (substrate, wafer, and sample are collectively referred to as "sample" hereinafter). One or more robotic arms (not shown) in the EFEM 30 transport the sample to the load lock chamber 20.

[0037] The load lock chamber 20 is used to remove the gas around the sample. This creates a vacuum with a local gas pressure lower than the pressure in the surrounding environment. The load lock chamber 20 can be connected to a load lock vacuum pump system (not shown), which removes gas particles in the load lock chamber 20. The operation of the load lock vacuum pump system enables the load lock chamber to reach a first pressure lower than atmospheric pressure. After reaching the first pressure, one or more mechanical arms (not shown) transport the sample from the load lock chamber 20 to the main chamber 10. The main chamber 10 is connected to the main chamber vacuum pump system (not shown). The main chamber vacuum pump system removes gas particles in the main chamber 10 so that the pressure around the sample reaches a second pressure lower than the first pressure. After reaching the second pressure, the sample is transported to the electron optical device 40, and the sample can be inspected by the electron optical device 40. The electron optical device 40 includes an electron optical device 41 (which can be referred to as a charged particle device). The electron optical device 41 can be an electron optical column (column) configured to project at least one electron beam toward the sample 208, and / or an objective lens module configured to focus at least one electron beam onto the sample 208. The electron optical device 41 may also include a detector module configured to detect electrons emitted from the sample 208, and / or a control lens module configured to adjust the electron optical parameters of at least one electron beam. In one embodiment, the electron optical column may include an objective lens module and a detector module and an optional control lens module. In one embodiment, the electron optical device includes an objective lens assembly, which may be included in the electron optical column. The objective lens assembly includes an objective lens array associated with (e.g., integrated with) one or more other electron optical components (e.g., a detector array and an optional control lens array). The electron optical device 41 may be a multi-beam electron optical device 41 for projecting multiple beams toward the sample 208. In one embodiment, the electron optical device 41 includes multiple devices (or columns), which include multiple electron optical devices, which are configured to project corresponding electron beams or electron multi-beams toward the sample 208.

[0038] The controller 50 is electronically connected to the electron optical device 41 of the electron optical device 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 circuit device configured to perform various signal and image processing functions. Figure 1Controller 50 is shown as being outside the structure including main chamber 10, load lock chamber 20 and EFEM 30, but it is understood that controller 50 can be part of the structure. Controller 50 can be located in one of the constituent elements of the charged particle beam inspection device, or it can be distributed on at least two constituent elements. Although the present disclosure provides an example of a main chamber 10 that accommodates an electron beam inspection device, it should be noted that aspects of the present disclosure are not limited to chambers that accommodate electron beam inspection tools in their broadest sense. On the contrary, it is understood that the aforementioned principles can also be applied to other systems and other device arrangements that operate at a second pressure.

[0039] Reference now Figure 2 , Figure 2 is a schematic diagram illustrating an exemplary electron optical apparatus 40, the electron optical apparatus 40 includes a multi-beam electron optical device 41, which is Figure 1 1 and 2. The electron optical device 40 includes an electron source 201 and a projection device 230. The electron optical device 40 also includes a motorized stage 209 and a sample holder 207. The projection device 230 can be referred to as an electron optical device 41. 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 optical device 41 can also include a detector 240 (e.g., an electron detection device).

[0040] 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. The electron source 201 may include multiple sources, such as those described in patent application number EP20184161.6, which is incorporated herein by reference, at least with respect to multiple sources and how they are related to multiple columns and their associated electron optical devices.

[0041] Projection device 230 is configured to convert primary electron beam 202 into multiple charged particle beams 211, 212, 213 and direct each beamlet onto sample 208. Although three beamlets are illustrated for simplicity, there may be tens, hundreds or thousands of beamlets. A beamlet may be referred to as a beam wave.

[0042] The controller 50 may be connected to Figure 1 The controller 50 may be connected to the various parts of the charged particle beam inspection device 100. Figure 2The controller 50 may be used to control various parts of the electron optical device 40, such as the electron source 201, the detector 240, the projection device 230 and the motorized stage 209 (or the brake stage). The controller 50 may perform various image and signal processing functions. The controller 50 may also generate various control signals to manage the operation of the charged particle beam inspection device 100, including the operation of the electron optical device 40.

[0043] The projection device 230 can be configured to, for example, focus the evaluation beamlets 211, 212, and 213 onto the sample 208 for inspection, and can form three detection spots 221, 222, and 223 on the surface of the sample 208. The projection device 230 can be configured to deflect the evaluation beamlets 211, 212, and 213 to scan the detection spots 221, 222, and 223 across various scanning areas in a section of the surface of the sample 208. In response to the evaluation beamlets 211, 212, and 213 being incident on the detection spots 221, 222, and 223 on the sample 208, signal charged particles (e.g., signal electrons) are generated (i.e., emitted) from the sample 208, which include secondary signal particles and backscattered signal particles. The signal particles emitted from the sample, such as secondary electrons and backscattered electrons, may also be referred to as charged particles, such as secondary charged particles and backscattered charged particles. The signal beam is formed by the signal particles emitted from the sample. It is generally understood that any signal beam emitted from the sample 208 will travel in a direction having at least one component substantially opposite to the charged particle beam (i.e., the main beam), or will have at least one directional component opposite to the direction of the main beam. The signal particles emitted by the sample 208 may also pass through the electrodes of the objective lens and also be affected by the field.

[0044] Secondary electrons typically have an electron energy of ≤50eV. Actual secondary electrons may have an energy of less than 5eV, but any energy below 50eV is generally considered a secondary electron. Backscattered electrons typically have an electron energy between 0eV and the landing energy of the evaluation beamlets 211, 212, and 213. Since electrons detected with energies less than 50eV are generally considered secondary electrons, a portion of the actual backscattered electrons will be considered secondary electrons. Secondary signal particles may be more specifically referred to as secondary electrons and may be interchangeable with secondary electrons. Backscattered signal particles may be more specifically referred to as backscattered electrons and may be interchangeable with backscattered electrons. Those skilled in the art will appreciate that backscattered signal particles may be more generally described as secondary signal particles. However, for the purposes of this disclosure, backscattered signal particles are considered to be different from secondary signal particles, for example, having higher energy. In other words, secondary signal particles will be understood as particles with a kinetic energy of ≤50eV when emitted from a sample, and backscattered signal particles will be understood as particles with a kinetic energy higher than 50eV when emitted from a sample. In practice, signal particles may be accelerated before being detected, so the energy range associated with signal particles may be slightly higher. For example, secondary signal particles will be understood as particles with a kinetic energy ≤ 200eV when detected at the detector, and backscattered signal particles will be understood as particles with a kinetic energy above 200eV when detected at the detector. It is worth noting that the value of 200eV may vary depending on the degree of particle acceleration, for example, it may be about 100eV or 300eV. Secondary signal particles with such values ​​are still considered to have sufficient energy difference from backscattered signal particles.

[0045] The detector 240 is configured to detect (e.g., capture) signal particles such as secondary electrons and / or backscattered electrons and generate corresponding signals, which are sent to the signal processing system 280, for example, to construct an image of the corresponding scan area of ​​the sample 208. The detector 240 can be incorporated into the projection device 230. The detector array can also be called a sensor array, and the terms "detector" and "sensor" and "sensor unit" are used interchangeably throughout the application.

[0046] The signal processing system 280 may include circuitry (not shown) configured to process signals from the detector 240 to form an image. The signal processing system 280 may also be referred to as an image processing system. The signal processing system may be incorporated into a component of the multi-beam electron optical device 40 (e.g., the detector 240) (e.g., Figure 2 However, the signal processing system 280 may be incorporated into any component of the electron beam detection device 100 or the multi-beam electron optical device 40, for example as a part of the projection device 230 or the controller 50. The signal processing system 280 may be located in a Figure 1The structure of the main chamber shown in . The signal processing system 280 may include an image acquirer (not shown) and a storage device (not shown). For example, the signal processing system may include a processor, a computer, a server, a mainframe, a terminal, a personal computer, any kind of mobile computing device, etc., or a combination thereof. The image acquirer may include at least a portion of the processing function of the controller. Therefore, the image acquirer may include at least one or more processors. The image acquirer may be communicatively coupled to a detector 240 that allows signal communication, such as an electrical conductor, a fiber optic cable, a portable storage medium, IR, Bluetooth, the Internet, a wireless network, radio, etc., or a combination thereof. The image acquirer may receive a detection signal from the detector 240, may process the data included in the signal, and may construct an image based thereon. The image acquirer may thus acquire an image of the sample 208. The image acquirer may also perform various post-processing functions, such as generating a contour, superimposing an indicator 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, a flash drive, a cloud storage device, a random access memory (RAM), other types of computer-readable memory, etc. The storage device may be coupled to the image acquirer and may be used to save the scanned raw image data as a raw image and a post-processed image.

[0047] The signal processing system 280 may include measurement circuitry (e.g., an analog-to-digital converter) to obtain a distribution of the detected secondary electrons. The electron distribution data collected during the detection time window may be used in conjunction with the corresponding scan path data of each of the evaluation beamlets 211, 212, and 213 incident on the sample surface to reconstruct an image of the inspected sample structure. The reconstructed image may be used to reveal various features of the internal or external structure of the sample 208. Thus, the reconstructed image may be used to reveal any defects that may be present in the sample.

[0048] The controller 50 may control the motorized stage 209 to move the sample 208 during the inspection of the sample 208. The controller 50 may enable the motorized stage 209 to move the sample 208 in a certain direction at least during the inspection of the sample, preferably continuously at a constant speed, for example. The controller 50 may control the movement of the motorized stage 209 so that it changes the movement speed of the sample 208 according to various parameters. For example, the controller 50 may control the stage speed (including its direction) according to the inspection step of the scanning process and / or the characteristics of the scanning.

[0049] Known multi-beam systems, such as the above-mentioned electron optical device 40 and electron beam inspection equipment 100, are disclosed in patent application numbers US2020118784, US20200203116, US2019 / 0259570 and US2019 / 0259564, and the above-mentioned documents are incorporated herein by reference.

[0050] Reference below Figure 3 Describing the components of an electro-optical device 40 that may be used in the present invention, Figure 3 is a schematic diagram of the electro-optical device 40 . Figure 3 The electron-optical device 40 may correspond to the above-described electron-optical device 40 (which may also be referred to as a system or a tool).

[0051] The electron source 201 guides electrons toward an array of converging lenses 231 (or referred to as a converging lens array). The electron source 201 is desirably a high brightness thermal field emitter with a good compromise between brightness and total emission current. There may be tens, hundreds or thousands of converging lenses 231. The converging lens 231 may include a multi-electrode lens and have a construction based on patent application number EP1602121A1, which is incorporated by reference, particularly in relation to the following disclosure: the lens array divides, for example, an electron beam from a source into a plurality of sub-beams, the array providing a lens for each sub-beam. The array of converging lenses 231 may take the form of at least two plates as electrodes, the apertures in each plate being aligned with each other and corresponding to the position of the sub-beams. At least two plates are maintained at different potentials during operation to achieve the desired lens effect.

[0052] In one arrangement, the array of converging lenses 231 is formed by three plate arrays, in which the charged particles have the same energy when they enter and leave each lens, which arrangement can be called an Einzel lens. Therefore, dispersion only occurs within the Einzel lens itself (between the entrance electrode and the exit electrode of the lens), thereby limiting off-axis chromatic aberration. When the thickness of the converging lens is very small, such as a few millimeters, this aberration has a small or negligible effect. More generally, the converging lens 231 can have two or more plate electrodes, each having an aligned aperture array. Each plate electrode array is mechanically connected and electrically isolated from an adjacent plate electrode array by an isolation element, which can include, for example, a ceramic or glass spacer. The converging lens can be connected and / or spaced apart from an adjacent charged particle optical element (preferably an electrostatic charged particle optical element) by an isolation element such as a spacer described elsewhere herein.

[0053] The converging lens can be separated from a module containing the objective lens (such as an objective lens array component described elsewhere herein). In the case where the potential applied to the bottom surface of the converging lens is different from the potential applied to the top surface of the module containing the objective lens, a separation element (e.g., a spacer) is used to separate the converging lens and the module containing the objective lens. In the case where the potentials are equal, a conductive element can be used to separate the converging lens and the module containing the objective lens.

[0054] Each converging lens 231 in the array guides electrons into a corresponding evaluation beamlet 211, 212, 213, which is focused at a corresponding intermediate focus downstream of the converging lens array. The corresponding beamlets are projected along each beamlet path 220. The beamlets diverge relative to each other. The beamlet path 220 diverges downstream of the converging lens 231. In one embodiment, a deflector 235 is provided at the intermediate focus. The deflector 235 is positioned at or at least around the position of the corresponding intermediate focus 233 or focus (i.e., the focal point) in the beamlet path. The deflector 235 is positioned at or near the beamlet path at the intermediate image plane of the associated beamlet. The deflector 235 is configured to operate on the corresponding evaluation beamlets 211, 212, 213. The deflector 235 is configured to bend the respective evaluation beamlets 211, 212, 213 by an amount effective to ensure that the primary ray (which may also be referred to as the beam axis) is incident on the sample 208 perpendicularly (i.e., substantially 90° to the nominal surface of the sample). The deflector 235 may also be referred to as a collimator or a collimator deflector. The deflector 235 effectively collimates the paths of the beamlets so that before the deflector, the beamlet paths are divergent relative to each other. Downstream of the deflector, the beamlet paths are substantially parallel to each other, i.e., substantially collimated. A suitable collimator is the deflector disclosed in EP application 20156253.5 filed on February 7, 2020, which is incorporated herein by reference with respect to the application of the deflector to a multi-beam array. Instead of or in addition to the deflector 235, the collimator may include a macro-collimator 270 (e.g., such as Figure 4 Therefore, the following Figure 4 The macro collimator 270 described may have Figure 3 This is generally less preferred than providing a collimator array as the deflector 235.

[0055] Below the deflector 235 (i.e., downstream or further from the electron source 201) there is a control lens array 250. The evaluation beamlets 211, 212, 213 that have passed through the deflector 235 are substantially parallel when entering the control lens array 250. The control lens pre-focuses the beamlets (e.g., applies a focusing action to the beamlets before the beamlets reach the objective lens array 241). Pre-focusing can reduce the divergence of the beamlets or increase the convergence rate of the beamlets. The control lens array 250 and the objective lens array 241 operate together to provide a combined focal length. Combined operation without an intermediate focus can reduce the risk of aberrations.

[0056] In more detail, it is desirable to use the control lens array 250 to determine the landing energy. However, the objective lens array 241 can be used in addition to control the landing energy. In this case, the potential difference on the objective lens changes when different landing energies are selected. An example of a situation in which it is desirable to partially change the landing energy by changing the potential difference on the objective lens is to prevent the focus of the sub-beam from being too close to the objective lens. In this case, there is a risk that the components of the objective lens array 241 must be too thin to be manufactured. The same applies to detectors at this position, such as in the objective lens, on the objective lens or otherwise associated with the objective lens. This situation can occur, for example, when the landing energy is reduced. This is because the focal length of the objective lens is roughly proportional to the landing energy used. By reducing the potential difference on the objective lens, the electric field inside the objective lens is reduced, so that the focal length of the objective lens becomes larger again, resulting in a focus position further below the objective lens. Note that using only the objective lens will limit the control of the magnification. Such an arrangement cannot control the reduction and / or opening angle. In addition, using the objective lens to control the landing energy may mean that the objective lens will operate with a deviation from its optimal field strength. That is, unless the mechanical parameters of the objective lens (such as the spacing between its electrodes) can be adjusted, for example by replacing the objective lens.

[0057] The control lens array 250 includes a plurality of control lenses. Each control lens includes at least one electrode, preferably two electrodes (e.g., two or three electrodes) connected to a corresponding potential source. The control lens array 250 may include one or more (e.g., three) plate electrode arrays connected to a corresponding potential source. The control lens array electrodes may be spaced a few millimeters (e.g., 3 mm). The control lens array 250 is associated with the objective lens array 241 (e.g., the two arrays are positioned close to each other and / or mechanically connected to each other and / or controlled together as a unit). Each control lens may be associated with a corresponding objective lens. The control lens array 250 is positioned upstream of the objective lens array 241. Upstream may be defined as closer to the source 201. In addition, upstream may be defined as away from the sample 208. The control lens array 250 may be in the same module as the objective lens array 241, i.e., forming an objective lens array assembly or an objective lens arrangement, or it may be in a separate module. In this case, the arrangement may be described as four or more lens electrodes as a plate. An aperture, such as an aperture array, is defined in the plate, which is aligned with a plurality of beamlets in the corresponding beam array. The electrodes can be grouped into two or more electrodes, for example providing a control electrode group and a target electrode group. In one arrangement, the objective electrode group has at least three electrodes, and the control electrode group has at least two electrodes. Alternatively, if the control lens array 250 and the objective lens array 240 are separated, the spacing between the control lens array 241 and the objective lens array 250 (i.e., the gap between the lower electrode of the control lens array 250 and the upper electrode of the objective lens 241) can be selected from a wide range, for example from 2mm to 200mm or more. Small spacing makes alignment easier, while larger spacing allows the use of weaker lenses, reducing aberrations.

[0058] Each plate electrode of the control lens array 250 is preferably mechanically connected and electrically isolated from the adjacent plate electrode array by an isolation element, which may include, for example, a ceramic or glass spacer. Each plate electrode of the objective lens array is preferably mechanically connected and electrically isolated from the adjacent plate electrode array by an isolation element, which may include, for example, a ceramic or glass spacer. In addition, the isolation element may be referred to as an insulating structure and may be provided to enable, for example, the objective lens array 240, the converging lens array (such as Figure 3 250) and / or control any adjacent electrodes provided in the lens array 250 to be separated. If more than two electrodes are provided, multiple isolation elements (ie, insulating structures) may be provided. For example, there may be a series of insulating structures.

[0059] The control lens array 250 can be considered as one or more electrodes in addition to the electrodes of the objective lens array 241. The control lens array 250 provides additional degrees of freedom for controlling the beamlets. A greater number of electrodes included in the control lens array 250 provides a greater number of degrees of freedom. For example, these additional electrodes can allow landing energy and / or magnification control independent of the field strength of the objective lens array 241. In some designs, the control lens can therefore be part of the objective lens. Therefore, such electrodes mentioned can be part of the objective lens, rather than a separate lens, such as a control lens. The reference to the control lens in this arrangement is a reference to the functionally equivalent electrode of the objective lens.

[0060] The control lens array 250 includes a control lens for each evaluation beamlet 211, 212, 213. The control lens adds an optical degree of freedom to the function of the associated objective lens. The control lens may include one or more electrodes or plates. The addition of each electrode may provide a further degree of freedom to control the charged particle optical function of the associated objective lens. In one arrangement, the function of the control lens array 250 is to optimize the beam opening angle and / or control the beam energy delivered to the objective lens relative to the reduction of the beam, each objective lens directing its respective evaluation beamlet 211, 212, 213 onto the sample 208. The objective lens array 241 may be positioned at or near the base of the electron optical system 41. More specifically, the objective lens array may be positioned at or near the base of the projection system 230. The control lens array 250 is optional, but is preferably used to optimize the beamlets upstream of the objective lens array 241.

[0061] For ease of explanation, this article uses an elliptical array to schematically describe the lens array (eg Figure 3 ). Each ellipse represents one of the lenses in the lens array. It is conventional to use ellipses to represent lenses, similar to the biconvex form often used in optical lenses. However, in the context of charged particle devices such as those discussed herein, it should be understood that the lens array will generally operate electrostatically and therefore any physical elements that take the form of biconvex shapes may not be required. The lens array may alternatively include multiple plates with apertures.

[0062] Optionally, a scanning deflector array 260 is provided between the control lens array 250 and the objective lens array 234. The scanning deflector array 260 comprises a scanning deflector for each evaluation beamlet 211, 212, 213. Each scanning deflector is configured to deflect the respective evaluation beamlet 211, 212, 213 in one or two directions so as to scan the beamlet across the sample 208 in one or two directions.

[0063] Figure 4is a schematic diagram of an exemplary electron-optical device 40 including a macro-collimator 270 and a macro-scanning deflector 265. An electron source 201 directs an electrode toward the macro-collimator 270. The electron source 201 is desirably a high brightness thermal field emitter with a good trade-off between brightness and total emission current.

[0064] For example, beamlets can be derived from the beam using a beamlet forming array 252 (also referred to as a beam limiting aperture array) that defines a beam limiting aperture array. The beam can be split into beamlets when encountering the control lens array 250, as described below. The beamlets are substantially parallel when entering the control lens array 250.

[0065] The macro collimator 270 acts on the beam from the source 201 before the beam is split into multiple beams. The macro collimator 270 bends the various portions of the beam by an amount effective to ensure that the beam axis of each beamlet derived from the beam is incident on the sample 208 substantially vertically (i.e., substantially 90° to the nominal surface of the sample 208). Therefore, the path of each beamlet is at least intended to be orthogonal to the surface of the sample 208. The macro collimator 270 applies macro collimation to the beam. Therefore, the macro collimator 270 can act on all beams, rather than including an array of collimator elements each configured to act on a different individual portion of the beam. The macro collimator 270 can include a magnetic lens or a magnetic lens arrangement including a plurality of magnetic lens subunits (e.g., a plurality of electromagnets forming a multipole arrangement). Alternatively or additionally, the macro collimator can be implemented at least in part electrostatically. The macro collimator can include an electrostatic lens or an electrostatic lens arrangement including a plurality of electrostatic lens subunits. The macro collimator 270 can use a combination of magnetic lenses and electrostatic lenses.

[0066] In another arrangement (not shown), the macro collimator 270 can be partially or completely replaced by an array of collimator elements provided downstream of the array of beamlet formation. Each collimator element collimates the corresponding beamlet. The array of collimator elements can be formed using MEMS manufacturing technology so as to be compact in space. The array of collimator elements can be the first deflection or focusing electron optical array element in the beam path downstream of the source 201. The array of collimator elements can be upstream of the control lens array 250. The array of collimator elements can be in the same module as the control lens array 250.

[0067] like Figure 4 As shown, in one embodiment, the electronic optical device 41 includes an objective lens array 241. The objective lens array 241 includes a plurality of objective lenses. The objective lens array 241 can be a replaceable module. The replaceable module can have other electronic optical elements, such as a detector array and / or a control lens array.

[0068] There is a control lens array 250 below the macro collimator 270 (i.e., downward beam or farther away from the electron source 201). The control lens array 250 is configured to apply a focusing effect to the beamlets before they reach the objective lens array. Pre-focusing can reduce the divergence of the beamlets or increase the convergence rate of the beamlets. The control lens array 250 and the objective lens array 241 operate together to provide a combined focal length. The combined operation without an intermediate focus can reduce the risk of aberrations. Additionally or alternatively, the control lenses in the control lens array 250 are configured to control the opening angle of the beamlets and / or control the reduction (i.e., magnification) of the beamlets and / or control the landing energy.

[0069] The control lens array 250 can be as described above with respect to Figure 3 As described. The control lens array 250 can be considered as one or more electrodes in addition to the electrodes of the objective lens array 241. The control lens array 250 provides additional degrees of freedom for controlling the sub-beams. A greater number of electrodes included in the control lens array 250 provides a greater number of degrees of freedom. For example, these additional electrodes can allow landing energy and / or magnification control independent of the field strength of the objective lens array 241. In some designs, the control lens can therefore be part of the objective lens. Therefore, such an electrode can be part of the objective lens, rather than a separate lens, such as a control lens.

[0070] The control lens array 250 comprises a control lens for each evaluation beamlet 211, 212, 213. The function of the control lens array 250 is to optimize the beam opening angle relative to the beam reduction and / or to control the beam energy delivered to the objective lens array 241, which directs the evaluation beamlets 211, 212, 213 onto the sample 208. The objective lens array 241 may be positioned at or near the substrate of the electron-optical device 41. The control lens array 250 is preferably used to optimize the beamlets upstream of the objective lens array 241.

[0071] exist Figure 4 In an embodiment of the present invention, a macro scanning deflector 265 is provided to scan the beamlets over the sample 208. The macro scanning deflector 265 deflects portions of the beam so that the beamlets are scanned over the sample 208. In one embodiment, the macro scanning deflector 265 comprises a macro multipole deflector, for example having eight poles or more. The deflection causes the beamlets derived from the beam to be scanned across the sample 208 in one direction (e.g., parallel to a single axis, such as the X-axis) or in two directions (e.g., relative to two non-parallel axes, such as the X-axis and the Y-axis). The macro scanning deflector 265 acts on all of the beams macroscopically, rather than including an array of deflector elements each configured to act on a different individual portion of the beam. In the embodiment shown, the macro scanning deflector 265 is disposed between the macro collimator 270 and the control lens array 250.

[0072] In another arrangement (not shown), the macro scanning deflector 265 can be partially or completely replaced by a scanning deflector array. The scanning deflector array includes a plurality of scanning deflectors. The scanning deflector array can be formed using MEMS manufacturing technology. Each scanning deflector scans a corresponding sub-beam on the sample 208. Therefore, the scanning deflector array can include a scanning deflector for each sub-beam. Each scanning deflector can deflect the sub-beam in one direction (e.g., parallel to a single axis, such as the X-axis) or in two directions (e.g., relative to two non-parallel axes, such as the X-axis and the Y-axis). The deflection causes the sub-beam to be scanned across the sample 208 in one or two directions (i.e., one dimension or two dimensions). The scanning deflector array can be upstream of the objective lens array 241. The scanning deflector array can be downstream of the control lens array 250. Although reference is made to a single sub-beam associated with a scanning deflector, a group of sub-beams can be associated with a scanning deflector. In one embodiment, the scanning deflector described in EP2425444, which is hereby incorporated by reference in its entirety, particularly with respect to scanning deflectors, can be used to implement a scanning deflector array. A scanning deflector array (e.g., formed using MEMS manufacturing techniques as described above) can be more spatially compact than a macro scanning deflector. The scanning deflector array can be in the same module as the objective lens array 241.

[0073] In other embodiments, a macro scanning deflector 265 and a scanning deflector array are provided. In such an arrangement, the scanning of the beamlets on the sample surface can be achieved by controlling the macro scanning deflector and the scanning deflector array together, preferably synchronously.

[0074] In some embodiments, the electron optical device 41 also includes a beamlet forming array 252. The beamlet forming array 252 defines a beam limiting aperture array. The beamlet forming array 252 may be referred to as an upper beam limiting aperture array or an upstream beam limiting aperture array. The beamlet forming array 252 may include a plate (which may be a plate-like body) having a plurality of apertures. The beamlet forming array 252 forms beamlets from an electron beam emitted by the source 201. Portions of the beam other than the portion that contributes to forming the beamlet may be blocked (e.g., absorbed) by the beamlet forming array 252 so as not to interfere with the beamlet downstream. The beamlet forming array 252 may be referred to as a beamlet defining aperture array or an upper beam limiter. The aperture of the beamlet forming array 252 may have a diameter 72 of at least 20 μm, optionally at least 50 μm, optionally at least 100 μm, and optionally 120 μm (see Fig.12 ). The spacing of these apertures may be equal to the spacing of the apertures of beam aperture 406.

[0075] In some embodiments, Figure 4As shown, the electron optical device 41 is an objective lens array assembly (which is a unit including the objective lens array 241) and includes a beam shaping aperture array 262. The beam shaping aperture array 262 defines a beam limiting aperture array. The beam shaping aperture array 262 may be referred to as a lower beam limiter, a lower beam limiting aperture array, or a final beam limiting aperture array. The beam shaping aperture array 262 may include a plate (which may be a plate-shaped body) having a plurality of apertures. The beam shaping aperture array 262 may be downstream of at least one electrode (optionally from all electrodes) of the control lens array 250. In some embodiments, the beam shaping aperture array 262 is downstream of at least one electrode (optionally all electrodes) of the objective lens array 241.

[0076] In one configuration, the beam shaping aperture array 262 is structurally integrated with the electrodes of the objective lens array 241. Desirably, the beam shaping aperture array 262 is positioned in an area of ​​low electrostatic field strength. Each beam limiting aperture is aligned with a corresponding objective lens in the objective lens array 241. The alignment allows a portion of a beamlet from the corresponding objective lens to pass through the beam limiting aperture and impinge on the sample 208. Each beam limiting aperture has a beam limiting effect, allowing only a selected portion of the beamlets incident on the beam shaping aperture array 262 to pass through the beam limiting aperture. The selected portion may be such that only a portion of the corresponding beamlet that passes through the central portion of the corresponding aperture in the objective lens array reaches the sample. The central portion may have a circular cross-section and / or be centered on the beam axis of the beamlet.

[0077] Any electron optical device 40 described herein may also include a detector 240. The detector 240 detects signal particles, such as electrons, emitted from the sample 208. The detected electrons may include any electrons detected by the SEM, including secondary and / or backscattered electrons emitted from the sample 208. An exemplary structure of the detector 240 is shown in Figure 7 shown in and referenced below Figure 8-Figure 10 Describe in more detail.

[0078] Figure 5 An electro-optical device 40 according to an embodiment is schematically shown. The same features as described above are indicated by the same reference numerals. For the sake of simplicity, reference is not made to Figure 5 These features are described in detail.For example, source 201, macrocollimator 270, objective lens array 241, and sample 208 may be as described above.

[0079] In one embodiment, the electron optical device 40 includes an array converging lens 231. There may be tens, hundreds or thousands of converging lenses 231. The converging lens 231 may include a multi-electrode lens and have a construction based on EP1602121A1, which is incorporated herein by reference, particularly in relation to the following disclosure: the lens array divides the electron beam into a plurality of sub-beams, the array providing a lens for each sub-beam. The array of converging lenses 231 may take the form of at least two plates as electrodes, the apertures in each plate being aligned with each other and corresponding to the position of the sub-beams. During operation, at least two plates are maintained at different potentials to achieve the desired lens effect.

[0080] In one arrangement, the array of converging lenses 231 is formed by an array of three plates, where the electrons have the same energy when entering and leaving each lens, which arrangement can be referred to as an einzel lens. Therefore, the dispersion occurs only within the einzel lens itself (between the entrance and exit electrodes of the lens), thereby limiting off-axis chromatic aberration. When the thickness of the converging lenses is small, such as a few millimeters, this aberration has a small or negligible effect.

[0081] As described above, in one embodiment, the detector 240 is between the objective lens array 241 and the sample 208. The detector 240 may face the sample 208. Alternatively, Figure 5 As shown, in one embodiment, an objective lens array 241 including a plurality of objective lenses is between the detector 240 and the sample 208 .

[0082] In one embodiment, the deflector array 95 is between the detector 240 and the objective lens array 241. In one embodiment, the deflector array 95 includes a Wien filter so that the deflector array can be referred to as a beam splitter. The deflector array 95 is configured to provide a magnetic field to dissociate electrons projected to the sample 208 from secondary electrons from the sample 208.

[0083] In one embodiment, the detector 240 is configured to detect signal particles by reference to the energy of the electrons (i.e., depending on the band gap). Such a detector 240 may be referred to as an indirect current detector. The secondary electrons emitted from the sample 208 gain energy from the field between the electrodes. The secondary electrodes have sufficient energy once they reach the detector 240.

[0084] Figure 6 yes Figure 5 A close-up view of a portion of the electron-optical device 40 is shown. In one embodiment, the detector 240 includes an electron-photon converter array 91. The electron-photon converter array 91 includes a plurality of fluorescent strips 92. Each fluorescent strip 92 is located in the plane of the electron-photon converter array 91. At least one fluorescent strip 92 is arranged between two adjacent electron beams projected toward the sample 208.

[0085] In one embodiment, the fluorescent strips 92 extend substantially in a horizontal direction. Alternatively, the electron-photon converter array 91 may comprise a sheet of fluorescent material having openings 93 for projected electron beams.

[0086] Figure 6 The projection electron beam shown by the middle dashed line passes through the plane of the electron-photon converter array 91 and is projected toward the deflector array 95 via the openings 93 between the fluorescent strips 92 .

[0087] In one embodiment, the deflector array 95 includes a magnetic deflector 96 and an electrostatic deflector 97. The electrostatic deflector 97 is configured to counteract the deflection of the projected electron beam transmitted toward the sample 208 by the magnetic deflector 96. As a result, the projected electron beam can move to a small extent in the horizontal plane. The beam downstream of the deflector array 95 is substantially parallel to the beam upstream of the deflector array 95.

[0088] In one embodiment, the objective lens array 241 includes a plurality of plates for directing secondary electrons generated in the sample 208 toward the deflector array 95. For secondary electrons traveling in the opposite direction relative to the projected electron beam, the electrostatic deflector 97 does not cancel the deflection of the magnetic deflector 96. Instead, the deflections of the secondary electrons caused by the electrostatic deflector 97 and the magnetic deflector 96 are added. Thus, the secondary electrons are deflected to travel at an angle relative to the optical axis so that the secondary electrons are transmitted to the fluorescent strips 92 of the detector 240.

[0089] At the fluorescent strip 92, photons are generated upon the incidence of secondary electrons. In one embodiment, the photons are transmitted from the fluorescent strip 92 to a photodetector (not shown) via a photon transmission unit. In one embodiment, the photon transmission unit comprises an array of optical fibers 98. Each optical fiber 98 comprises an end portion, the end portion being arranged adjacent to or attached to one of the fluorescent strips 92 for coupling photons from the fluorescent strip 92 into the optical fiber 98, and the other end portion being arranged to project the photons from the optical fiber 98 onto the photodetector.

[0090] The objective lens array 241 of any embodiment may include at least two electrodes in which an aperture array is defined. In other words, the objective lens array includes at least two electrodes having a plurality of holes or apertures. Adjacent electrodes of the objective lens array 241 are spaced apart from each other along the beamlet path. The distance between adjacent electrodes along the beam path is less than the size of the objective lens (along the beam path, i.e., between the most upstream and most downstream electrodes of the objective lens array), and an insulating structure may be positioned in the beam path as described below. Figure 7Electrodes 242, 243 are shown, which are part of an exemplary objective lens array 241 with respective aperture arrays 245, 246. The position of each aperture in the electrode corresponds to the position of the corresponding aperture in the other electrode. The corresponding apertures operate on the same beam, sub-beam or beam group in the multi-beam in use. In other words, the corresponding apertures in at least two electrodes are aligned with the beamlet path (i.e., one of the beamlet paths 220) and arranged along the beamlet path. Therefore, each electrode has an aperture through which the corresponding evaluation beamlets 211, 212, 213 propagate.

[0091] The aperture arrays 245, 246 of the objective lens array 241 may include multiple apertures, preferably with a substantially uniform diameter d. However, as described in EP application 20207178.3 filed on November 12, 2020, there may be some variations for optimizing aberration correction, which is incorporated herein by reference, at least in terms of achieving correction by changing the aperture diameter. The diameter d of the aperture in at least one electrode may be less than about 400 μm. Preferably, the diameter d of the aperture in at least one electrode is between about 30 and 300 μm. For a given aperture spacing, a smaller aperture diameter can provide a larger detector of the detector array 240, thereby increasing the chance of capturing backscattered signal particles. Therefore, the signal for backscattered signal particles can be improved. However, an aperture with too small a risk can lead to aberrations in the primary beamlet. Multiple apertures in the electrode may be spaced apart by a spacing P from each other. The spacing P is defined as the distance from the middle of an aperture to the middle of an adjacent aperture. The spacing between adjacent apertures in at least one electrode may be less than about 600 μm. Preferably, the spacing between adjacent apertures in at least one electrode is between about 50 μm and 500 μm. Preferably, the spacing between adjacent apertures on each electrode is substantially uniform. The above diameter and / or spacing values ​​may be provided in at least one electrode, a plurality of electrodes, or all electrodes in the objective lens array. Preferably, the dimensions mentioned and described apply to all electrodes provided in the objective lens array.

[0092] The objective lens array 241 may include two electrodes (such as Figure 7The objective lens array 241 having only two electrodes may have fewer aberrations, such as lower risk and / or impact of aberrations, than an objective lens array 241 having more electrodes. A three-electrode objective lens may have a greater potential difference between the electrodes, thereby enabling a stronger lens. Additional electrodes (i.e., more than two electrodes) provide additional degrees of freedom for controlling electron trajectories, such as focusing secondary electrons as well as the incident beam. Such additional electrodes may be considered to form a control lens array 250. An advantage of a two-electrode lens over a single lens is that the energy of the incoming beam does not have to be the same as the outgoing beam. Advantageously, the potential difference on such a two-electrode lens array enables it to be used as an acceleration or deceleration lens array.

[0093] Adjacent electrodes of the objective lens array 241 are spaced apart from each other along the beamlet path. The distance between adjacent electrodes is greater than the objective lens, and insulating structures can be positioned as described below in adjacent electrodes. The objective lens array 241 can be configured to reduce the charged particle beam to less than one-tenth, preferably within a range of one-fiftieth to one-hundredth or less. Each element in the objective lens array 240 can be a microlens that operates different beamlets or beamlet groups in the multi-beam.

[0094] Preferably, each electrode disposed in the objective lens array 241 is a plate. The electrode may be described as a flat sheet in addition. Preferably, each electrode is planar. In other words, each electrode will preferably be provided as a thin, flat plate in planar form. Of course, the electrode does not need to be planar. For example, the electrode may bend due to the force generated by the high electrostatic field. Planar electrodes are preferably provided because this makes the manufacture of the electrode easier because known manufacturing methods can be used. Planar electrodes may also be preferred because they can provide more accurate aperture alignment between different electrodes.

[0095] The objective lens array 241 can be configured to reduce the electron beam by less than one-tenth, desirably in the range of one-fiftieth to one-hundredth or less.

[0096] A detector 240 is provided to detect secondary electrons and / or backscattered electrons emitted from the sample 208. The detector 240 is positioned between the objective lens 234 and the sample 208. The detector 240 may additionally be referred to as a detector array or a sensor array, and the terms "detector" and "sensor" are used interchangeably in the application.

[0097] In one embodiment, the electron optical device 41 is configured to project an electron beam toward the sample 208. The electron optical device 41 may include an objective lens array 241. The electron optical device 41 may include a detector 240. The objective lens array (i.e., objective lens array 241) may correspond to an array of detectors (i.e., detector 240) and / or any beam (i.e., sub-beam).

[0098] An exemplary detector 240 is described below. However, any reference to detector 240 may be to a single detector (i.e., at least one detector) or to a plurality of detectors as appropriate. Detector 240 may include a detector element 405 (e.g., a sensor element such as a capture electrode). Detector 240 may include any suitable type of detector. For example, a capture electrode, a scintillator, or a PIN element, such as for direct detection of electron charge, may be used. Detector 240 may be a direct current detector or an indirect current detector. Detector 240 may be as follows with respect to Figure 8-Figure 10 The detector.

[0099] The detector 240 may be positioned between the objective lens array 241 and the sample 208. The detector 240 is configured to be close to the sample 208. The detector 240 may be very close to the sample 208. Alternatively, there may be a larger gap between the detector 240 and the sample 208. The detector 240 may be positioned in the device so as to face the sample 208. Alternatively, the detector 240 may be positioned elsewhere in the electron-optical device 41 so that the portion of the electron-optical device facing the sample 208 is not a detector and is therefore not a detector. For example, the detector 240 may have at least a portion associated with an electrode of the objective lens array 241.

[0100] for Figure 2-Figure 5 For a multi-beam system of the type shown, preferably the distance between the electron optical column and the sample 208 is less than or equal to about 50 μm. This distance is determined from the surface of the sample 208 facing the electron optical column to the surface of the electron optical column facing the sample 208.

[0101] Figure 8 4 is a bottom view of detector 240, which includes a substrate 404 on which a plurality of detector elements 405 are provided, each surrounding a beam aperture 406. Beam aperture 406 may be formed by etching through substrate 404. Figure 8 In the arrangement shown, the beam apertures 406 are in a hexagonal close-packed array. The beam apertures 406 may also be arranged differently, such as in a rectangular array. Figure 8 The hexagonal arrangement of the beam arrangement in may be more densely packed than the square beam arrangement. The detector elements 405 may be arranged in a rectangular array or a hexagonal array.

[0102] In one embodiment, the beam apertures 406 have a pitch P of at least 50 μm, optionally at least 100 μm, optionally at least 200 μm, and optionally 210 μm. A larger pitch allows the diameter d of the beam apertures 406 to be larger. In one embodiment, the beam apertures 406 have a pitch P of at most 1000 μm, optionally at most 500 μm, and optionally at most 250 μm. The pitch of the beam apertures 406 defines the pitch of the beamlets of the electron multibeams projected toward the sample 208. In one embodiment, the beamlets of the electron multibeams have a pitch of at least 50 μm, optionally at least 100 μm, optionally at least 200 μm, and optionally 210 μm. In one embodiment, the diameter d of the beam apertures 406 is less than the pitch P. In one embodiment, the beam apertures 406 have a diameter d of at least 10 μm, and optionally at least 20 μm. In one embodiment, the beam aperture 406 has a diameter d of at most 100 μm, optionally at most 50 μm, and optionally at most 30 μm. A smaller diameter d improves resolution, allowing smaller defects to be detected.

[0103] Fig. 9 A cross section of a portion of the detector 240 is depicted at a larger scale. The detector element 405 forms the bottommost portion of the detector 240, i.e. the surface closest to the sample 208. A logic layer 407 may be provided between the detector element 405 and the bulk of the substrate 404. At least a portion of the signal processing system may be incorporated into the logic layer 407.

[0104] The wiring layer 408 is disposed on the back side of the substrate 404 or within the substrate 404 and is connected to the logic layer 407 through through-substrate vias 409. The number of through-substrate vias 409 does not need to be the same as the number of beam apertures 406. In particular, if the electrode signals are digitized in the logic layer 407, only a small number of through-silicon vias may be required to provide a data bus. The wiring layer 408 may include control lines, data lines, and power lines. It should be noted that despite the beam apertures 406, there is enough space for all necessary connections. The detection module 402 can also be manufactured using bipolar or other manufacturing techniques. A printed circuit board and / or other semiconductor chip can be provided on the back side of the detector 240.

[0105] The above-described integrated detector array is particularly advantageous when used with a tool having a tunable landing energy, as secondary electron capture can be optimized for a range of landing energies.

[0106] The detector 240 can be implemented by integrating a CMOS chip detector into the bottom electrode of the objective lens array 241. Integrating the detector 240 into the objective lens array 241 or other components of the electron optical device 41 allows detection of electrons emitted relative to multiple corresponding sub-beams. The CMOS chip is preferably oriented to face the sample (because the distance between the sample and the bottom of the electron optical column is small (e.g., 50 μm or less)). In one embodiment, a detector element 405 for capturing secondary electrons is formed in the surface metal layer of the CMOS device. The detector element 405 can be formed in other layers. The power and control signals of the CMOS can be connected to the CMOS through through-silicon vias. For robustness, preferably, a passive silicon substrate with holes shields the CMOS chip from high electric fields.

[0107] In order to maximize the detection efficiency, it is desirable to make the surface of the detector element 405 as large as possible so that substantially all areas of the objective lens array 240 (except for the aperture) are occupied by the detector element 405. Additionally or alternatively, each detector element 405 has a diameter substantially equal to the array pitch (i.e., the aperture array pitch described above with respect to the electrodes of the objective lens assembly 241). Thus, the diameter of each detector element may be less than about 600 μm, and preferably between about 50 μm and 500 μm. As described above, the pitch may be selected based on the expected distance between the sample 208 and the detector 240. In one embodiment, the outer shape of the detector element 405 is circular, but this may be made square to maximize the detection area. The diameter of the through-substrate via 409 may also be minimized. The typical size of the electron beam is on the order of 5 to 15 microns.

[0108] In one embodiment, a single detector element 405 surrounds each beam aperture 406. In another embodiment, multiple detector elements 405 are provided around each beam aperture 406. Electrons captured by the detector elements 405 surrounding one beam aperture 406 can be combined into a single signal or used to generate independent signals. The detector elements 405 can be divided radially. The detector elements 405 can form multiple concentric rings or rings. The detector elements 405 can be divided angularly. The detector elements 405 can form multiple sectors or segments. The segments can have similar angular dimensions and / or similar areas. The electrode elements can be divided radially and angularly or in any other convenient manner.

[0109] However, a larger surface of the detector element 405 results in a larger parasitic capacitance and therefore a lower bandwidth. For this reason, it may be desirable to limit the outer diameter of the detector element 405. In particular, larger detector elements 405 give only slightly greater detection efficiency, but significantly greater capacitance. Circular (ring-shaped) detector elements 405 may provide a good compromise between collection efficiency and parasitic capacitance.

[0110] A larger outer diameter of the detector element 405 may also result in greater crosstalk (sensitivity to signals of neighboring wells). This may also be a reason to make the outer diameter of the detector element 405 smaller. Especially if a larger detector element 405 gives only slightly greater detection efficiency, but significantly greater crosstalk.

[0111] The electron current collected by the detector element 405 is amplified, for example, by an amplifier such as a TIA.

[0112] In one embodiment, the objective lens array 241 is a replaceable module, either by itself or in combination with other elements such as the control lens array 250 and / or the detector 240 and / or the beam shaping aperture array 262 and / or the sub-beam shaping array 252. The replaceable module can be field replaceable, i.e., the module can be replaced with a new module by a field engineer. In one embodiment, a plurality of replaceable modules are included in the tool and can be exchanged between an operable position and an inoperable position without opening the electron-optical device 40.

[0113] In one embodiment, the replaceable module includes an electron optical component, and specifically can be an electron optical device, which allows actuation to position the component on the stage. In one embodiment, the exchangeable module includes a stage. In one arrangement, the stage and the replaceable module can be an integral part of the tool 40. In one arrangement, the replaceable module is limited to the stage and the equipment it supports, such as the electron optical device. In one arrangement, the stage is removable. In another design, the replaceable module including the stage is removable. The portion of the electron optical device 40 for the exchangeable module is isolable, that is, the portion of the electron optical device 40 is defined by the valve upstream and valve downstream of the exchangeable module. The valve can be operated to isolate the valve from the environment between the vacuum upstream and downstream of the valve, respectively, so that the replaceable module can be removed from the electron optical device 40 while maintaining the vacuum upstream and downstream of the portion of the electron optical device 40 associated with the replaceable module. In one embodiment, the exchangeable module includes a stage. The stage is configured to support equipment such as an electron optical device relative to the beam path. In one embodiment, the module includes one or more actuators. The actuator is associated with the stage. The actuator is configured to move the device relative to the beam path. Such actuation can be used to align the device and the beam path relative to each other.

[0114] In one embodiment, the replaceable module is a micro-electromechanical system (MEMS) module. MEMS are miniaturized mechanical and electromechanical components manufactured using micro-fabrication techniques. In one embodiment, the replaceable module is configured to be replaceable within the electron-optical device 40. In one embodiment, the replaceable module is configured to be field replaceable. Field replaceable means that the module can be removed and replaced with the same or different module while maintaining the vacuum in which the electron-optical tool 40 is located. Only the portion of the electron-optical device 40 corresponding to the module is ventilated so that the module is removed and returned or replaced.

[0115] The control lens array 250 may be in the same module as the objective lens array 241, ie forming an objective lens array component or an objective lens row arrangement or it may be in a separate module.

[0116] In some embodiments, one or more aberration correctors are provided that reduce one or more aberrations in a beamlet. One or more aberration correctors may be provided in any embodiment, for example as part of an electronic optical device, and / or as part of an optical lens array assembly, and / or as part of an evaluation system. In one embodiment, each aberration corrector in at least a subset of the aberration correctors is positioned in or directly adjacent to a corresponding one of the intermediate focuses (e.g., in or adjacent to an intermediate image plane). The beamlet has a minimum cross-sectional area in or near a focal plane such as the intermediate plane. This provides more room for the aberration corrector than would otherwise be available (i.e., upstream or downstream of the intermediate plane) (or than would be available in an alternative arrangement without an intermediate image plane).

[0117] In one embodiment, an aberration corrector positioned in or directly adjacent to the intermediate focus (or intermediate image plane) includes a deflector to correct for the source 201 appearing to be in different positions for different beams. The corrector can be used to correct for macroscopic aberrations produced by the light source that prevent good alignment between each beamlet and the corresponding objective.

[0118] The aberration corrector can correct aberrations that prevent correct column alignment. Such aberrations may also cause misalignment between the beamlets and the corrector. To this end, it may be desirable to additionally or alternatively position the aberration corrector at or near the converging lens 231 (e.g., each such aberration corrector is integrated with or directly adjacent to one or more converging lenses 231). This is desirable because at or near the converging lens 231, the aberrations also do not cause a shift in the corresponding beamlets because the converging lens is vertically close to or coincides with the beam aperture. However, the challenge of positioning the corrector at or near the converging lens is that each beamlet has a relatively large cross-sectional area and a relatively small spacing at this position relative to a position further downstream. The aberration corrector can be an individual CMOS-based programmable deflector as disclosed in patent application EP2702595A1 or a multipole deflector array as disclosed in patent application EP2715768A2, the descriptions of the beam wave manipulator in these two documents are hereby incorporated by reference.

[0119] In some embodiments, each aberration corrector in at least a subset of the aberration correctors is integrated with or directly adjacent to the objective array 241. In one embodiment, the aberration correctors reduce one or more of: field curvature; focus error; and astigmatism. Additionally or alternatively, one or more scanning deflectors (not shown) may be integrated with or directly adjacent to the objective array 241 for scanning the evaluation beamlets 211, 212, 213 over the sample 208. In one embodiment, the scanning deflectors described in patent application US2010 / 0276606, which is incorporated herein by reference in its entirety, may be used.

[0120] The detector may have a plurality of parts, and more specifically, a plurality of detection parts. A detector comprising a plurality of parts may be associated with one of the evaluation beamlets 211, 212, 213. Thus, a plurality of parts of a detector 240 may be configured to detect signal particles emitted from the sample 208 associated with one of the primary beams (which may be further referred to as evaluation beamlets 211, 212, 213). In other words, a detector comprising a plurality of parts may be associated with an aperture in at least one electrode of the objective lens assembly. More specifically, as Fig.10 As shown, a detector 405 comprising multiple sections may be arranged around a single aperture 406, which provides an example of such a detector.

[0121] like Fig.10As shown, the detector element 405 includes an inner detection portion 405A and an outer detection portion 405B, and an aperture 406 is defined and configured in the detector element 405 for the electron beam to pass through. The inner detection portion 405A surrounds the aperture 406 of the detector. The outer detection portion 405B is radially outward from the inner detection portion 405A. The shape of the detector can generally be circular. Therefore, the inner detection portion and the outer detection portion can be concentric rings.

[0122] The present invention can be applied to a variety of different tool architectures. For example, the electron optical device 40 can include multiple electron optical columns of multiple beams. The electron optical column can include the electron optical device 41 described in any of the above embodiments or aspects. As multiple electron optical columns (or multi-column tools), these devices can be arranged in an array, which can be numbered from two to one hundred electron optical columns or more. The electron optical device 40 can take the form of Figure 4 Describing and depicting or as relating to Figure 5 The forms of embodiments described and depicted. The electron optical column may optionally include a source.

[0123] As described above, in order to increase the contrast of the electron beam inspection, the surface of the sample 208 can be illuminated with light before inspecting the sample 208. This process can be called advanced charge control. Such illumination can excite electrons within the sample 208. Such excited electrons within the sample 208 are more likely to interact with the impacting electrons from the primary sub-beams of the multi-beam incident. Therefore, such illumination can be used to increase the intensity of the signal particle signal. Light illumination can improve the contrast of the detection signal.

[0124] Fig.11 An electron optical apparatus is shown for evaluating a sample 208 using charged particles (e.g., electrons). The apparatus includes a preparatory electron optical device 102, an evaluation electron optical device 106, and a control system 500. The evaluation electron optical device 106 may include the electron optical device 41 described elsewhere in this document, for example, with reference to Figures 2 to 6 The control system 500 controls the device to perform various functions as described below. The control system 500 may include or be composed of the above reference Figure 1The control system 500 may be composed of a controller 50 of any form described. The control system 500 may include a single unit configured to perform all control functions, or may include a distributed system of units that together allow the desired functions to be achieved. The control system 500 may be at least partially implemented by a computer. Any suitable combination of elements (e.g., CPU, RAM, data storage, data connection means, sensors, etc.) may be provided and appropriately programmed to achieve some or even all specified functions. Any reference herein to a device, apparatus or system configured to perform a function is intended to cover the situation where the control system 500 is configured to cause a function to be performed (e.g., by being appropriately programmed to provide a control signal that causes the function to occur).

[0125] In one embodiment, the exposure of the target area comprises a flood exposure. The preparatory electron optical device 102 may comprise a flood column configured to provide a flood exposure. Fig.11 An example configuration of a flood column in a preliminary electron optical device 102 is shown, although other electron optical designs of a flood column can be used. In this example, the flood column includes a charged particle source 301, a converging lens 320, a blanker electrode 330, an objective lens 340, and an aperture body 350. The flood column may also include additional components for manipulating the preliminary charged particle beam 302, such as a scanning element (not shown) and a field lens (not shown). The components of the flood column may be arranged substantially along an axis 304.

[0126] The charged particle source 301 may be an electron source. The charged particle source 301 may include a charged particle emitting electrode (e.g., a cathode) and an accelerating electrode (e.g., an anode). The charged particles are extracted or accelerated from the charged particle emitting electrode by the accelerating electrode to form a preliminary charged particle beam 302. The preliminary charged particle beam 302 may propagate along a preliminary beam path 302. The preliminary beam path 302 may include an axis 304, for example, when the preliminary charged particle beam 302 does not deviate from the axis 304.

[0127] The converging lens 320 is positioned downstream of the charged particle source 301, that is, the converging lens 320 is positioned downstream relative to the charged particle source 301. The converging lens 320 can focus or defocus the preliminary charged particle beam 302. Fig.11 As shown, the converging lens 320 may be used to collimate the preliminary charged-particle beam 302. However, the converging lens 320 may also be used to control the preliminary charged-particle beam 302 to create a diverging beam or a converging beam.

[0128] The aperture body 350 may be positioned downstream of the converging lens 320. The aperture body 350 may allow a portion of the charged particle beam propagating along the axis 304 to pass through, or only a portion but not all of it. The aperture body 350 may limit the lateral extent of the preliminary charged particle beam 302, such as Fig.11 As depicted. The aperture body 350 can also be used to selectively blank the preliminary charged particle beam 302 to prevent any portion of the preliminary charged particle beam 302 from passing through. The aperture body 350 can define an opening. If the lateral extent (or diameter) of the preliminary charged particle beam 302 is greater than the lateral extent (or diameter) of the opening, only a portion of the preliminary charged particle beam 302 will pass through the opening. The aperture body 350 can therefore limit the lateral extent of the preliminary charged particle beam 302, thereby acting as a beam-limiting aperture.

[0129] The blanking electrode 330 may be positioned downstream of the converging lens 320 and upstream of the aperture body 350. The blanking electrode 330 may selectively deflect the preliminary charged particle beam 302, for example, deflecting the preliminary charged particle beam 302 away from the axis 304. The blanking electrode 330 may deflect the preliminary charged particle beam 302 away from the opening in the aperture body 350, for example, onto a portion of the aperture body 350 that does not include the opening, to prevent any portion of the preliminary charged particle beam 302 from passing through the opening defined by the aperture body 350. The blanking electrode 330 may blank the beam so that the beam does not pass through the opening of the aperture body 350. However, the combination of the blanking electrode 330 and the aperture body 350 may also be used to selectively blank the preliminary charged particle beam 302, i.e., selectively prevent at least a portion of the preliminary charged particle beam 302 from passing through the opening in the aperture body 350. That is, the combination of the blanking electrode 330 and the aperture body 350 can selectively control the proportion of the preliminary charged particle beam 302 passing through the opening.

[0130] The objective lens 340 is positioned downstream of the aperture body 350. The objective lens 340 can focus or defocus the preliminary charged particle beam 302. Fig.11 As shown, objective lens 320 can be used to control preliminary charged particle beam 302 to create a divergent beam, thereby increasing the spot size on sample 208 and increasing the surface area of ​​sample 208 that is flooded with charged particles. However, in some cases, objective lens 340 can be used to control charged particles 302 to create a converging beam, thereby focusing preliminary charged particle beam 302 onto sample 208.

[0131] In one embodiment, the evaluation electron optics 106 exposes the sample 208 to a plurality of beams of charged particles, the plurality of beams comprising a plurality of individual charged particle beams. Fig.11 The example of shows a multi-bundle comprising three individual bundles, but in practice the multi-bundle may comprise tens, hundreds or thousands of bundles.

[0132] In one embodiment, the evaluation electron optical device 106 includes an electron optical device 41. The electron optical device 41 can be taken as Figure 3 and Figure 7 Any form described, for example having an array of electron optical elements close to the sample 208, such as an array of objective lenses 241 or a detector array 240. In one embodiment, the evaluation electron optical device 106 includes an objective lens, which includes a plurality of objective lenses for evaluating different beams of the charged particle beam. Fig.11 In the specific example of Figure 3 The arrangement and may operate and / or take the above reference Figure 3 Electron-optical device 41 is used to direct charged particles onto sample 208 and detect signal charged particles from sample 208 during evaluation of sample 208 .

[0133] In one embodiment, an electron optical device is used to evaluate the sample at the evaluation location. Fig.11 In the example, the evaluation position is below the evaluation electron optical device 106. Fig.11 As shown, in one embodiment, the electron optical device includes an evaluation charged particle optical device 106, a preliminary charged particle optical device 102 and a light source 70. The evaluation charged particle optical device 106 is configured to project an evaluation charged particle beam 211-213 toward the evaluation position along the evaluation beam path. The evaluation charged particle beam is used to evaluate the sample 208 at the evaluation position. The preliminary charged particle optical device 106 is configured to project a preliminary charged particle beam along the preliminary beam path. The preliminary charged particle beam is used to prepare the sample for evaluation.

[0134] like Fig.11 As shown, in one embodiment, the electron optical device 40 includes a light source 70. The light source 70 can be a module or a part of a module configured to generate a light beam for light excitation of an irradiated surface and can be referred to as a module. Such a light source can be included in an advanced charge control module, such as an ACC module. The light source 70 is configured to project (or direct) a light beam 71 toward the sample 208. In one embodiment, the light source 70 is configured to project the light beam 71 toward the irradiation position. The light source 70 can be part of a projection system for irradiating a sample before evaluating at least a sample portion of the sample.

[0135] When the electron beam scans the sample 208, charges may accumulate on the sample 208 due to the large beam current, which may affect the quality of the image. The light source 70 may irradiate the beam 71 on the sample 208 to control the charges accumulated due to effects such as photoconductivity, photoelectric or thermal effects.

[0136] In one embodiment, the light source 70 is a laser light source. The laser provides a coherent light beam 71. However, other types of light sources may also be used. In one embodiment, the light source 70 is configured to emit a light beam 71 having a wavelength in the range of from 450nm to 850nm, preferably from 450nm to 800nm. The selected wavelength may correspond to a wavelength absorbed by the material of the sample 208. When the light is incident on the sample 208, the selected wavelength may tend to excite electrons in the sample 208. In one embodiment, the light source 70 is part of a projection component that includes an optical system. In one embodiment, the optical system is configured to focus the light beam 71.

[0137] By irradiating sample 208 with light beam 71, defect contrast is significantly improved. This technique may be referred to as voltage contrast and may be used to measure whether there is a proper electrical connection between a contact and the substrate of sample 208. Depending on the secondary electron yield (<1 or >1), a reverse diode is formed with the contact to the N+ or P+ doped region on the substrate. As a result, it may be the case that it is not possible to distinguish between a correct and a poor electrical connection for an N+ contact or a P+ contact. By irradiating sample 208 with light beam 71 (ACC), the reverse diode is turned on. As a result, in the case where there is a proper electrical connection between the contact and the substrate, the contact will not charge, but in the case of a poor electrical connection, the contact will charge.

[0138] The evaluation electron-optical device 106 may have a field of view. The field of view may be an area on the surface of the sample 208 onto which electrons projected by the evaluation electron-optical device 106 may be incident. The field of view may be 1 mm, for example 5 mm, for example 10 mm or even 20 mm. The evaluation electron-optical device 106 may have a large field of view. Since the electron-optical device is comprised in a substrate of, for example, silicon, the plate forming the most downstream beam surface of the device may be larger in surface area than the beam grid. The working distance between the evaluation electron-optical device 106 and the sample 208 may be limited (e.g., having a maximum value, for example, in the range of 10 to 100 microns, as described previously), for example for electron-optical reasons, as described herein with respect to Figures 2 to 5 The dimensions disclosed herein may produce a gap that is limited or small (e.g., narrow) in height (or in a direction along the beam path) and width (e.g., in a direction crossing or even orthogonal to the beam path). The gap may be considered narrow and wide. The dimensions of the gap may make it difficult to illuminate the sample for photoexcitation (or use of ACC) directed to the sample. For example, the trajectory of the light beam (e.g., that of the ACC) that reaches the inspection area (i.e., the surface area of ​​the sample 208 to be evaluated) will be greater than the grazing angle that prevents the sample 208 from absorbing light.

[0139] In one embodiment, the positional relationship between the irradiation position and the evaluation charged-particle optical device 106 is different from the positional relationship between the evaluation position and the evaluation charged-particle optical device 106. For example, in one embodiment, the evaluation position is different from the irradiation position. The sample 208 can be irradiated by the light beam 71 at a position different from the evaluation position. Alternatively, the sample 208 can remain stationary between irradiation and evaluation, and the electron-optical devices 102, 106 can be moved so that the relative position between the sample 208 and the electron-optical devices 102, 106 changes between irradiation and evaluation.

[0140] It is contemplated that embodiments of the present invention enable photon excitation (e.g., ACC) with an electron optical structure for evaluating electron optical device 106, where the bottom of the device has a small displacement from sample 208 and can have a large field of view.

[0141] In one embodiment, the field of view of the evaluation charged-particle optical device 106 at the evaluation position in a direction crosswise to the evaluation beam path is wider than the distance between the evaluation position and the evaluation charged-particle optical device 106 in a direction along the evaluation beam path.

[0142] In one embodiment, the preparation portion is a surface of the sample prepared by the preparation beam and the evaluation portion is a surface of the sample evaluated by the evaluation beam at the evaluation position, wherein the preparation portion is at least as large as the evaluation portion.

[0143] In one embodiment, the preparation portion corresponds to the field of view of the preparation beam and the evaluation portion corresponds to the field of view of the evaluation beam at the evaluation position.

[0144] In one embodiment, contacts that have poor electrical connections to the substrate are charged by the preparatory electron optical device 102 prior to evaluation. To ensure that both the N+ contacts and the P+ contacts that have proper electrical connections are not charged, the sample 208 can be illuminated by the light source 70 prior to evaluation. This can be done during projection of the preparatory beam (e.g., flood) or after projection of the preparatory beam. Because the beam illumination is done prior to evaluation, a small gap between the evaluation electron optical device 106 and the sample 208 is less of a problem. The light source 70 can be part of the preparatory electron optical device 102, rather than part of the evaluation electron optical device 106.

[0145] By controlling the landing energy of the electrons of the preparation electron beam, contacts with poor electrical connections can be charged positively or negatively. During the evaluation period, contacts with poor electrical connections will be further charged, and in addition, contacts with proper electrical connections but connected to a diode in reverse will also be further charged. In one embodiment, the charging during projection of the preparation electron beam and during projection of the evaluation electron beam is in the same direction, for example by projecting the preparation electron beam with the same landing energy as the landing energy of the evaluation electron beam.

[0146] During projection of a preliminary electron beam (e.g. during flooding), defective contacts are charged, "reverse diode" contacts are charged, while "switched-on diode" contacts remain discharged. During projection of the light beam 71, defective contacts remain charged, "reverse diode" contacts are discharged, while "switched-on diode" contacts remain discharged. During projection of the evaluation electron beam, defective contacts are further charged, "reverse diode" contacts are charged, while "switched-on diode" contacts remain discharged. It is possible to distinguish between defective contacts that are further charged and "reverse diode" contacts that are only charged. By performing projection of a preliminary electron beam and projection of the light beam, it is easier to distinguish between good contacts and bad contacts. It is not necessary to project the light beam simultaneously with the projection of the evaluation electron beam.

[0147] If the use of photon excitation (e.g., ACC) is mandatory for a particular voltage contrast application, it is expected that embodiments of the present invention will increase throughput, for example by allowing the use of photon excitation (e.g., ACC) in the context of devices with a large field of view and a small gap to the sample 208.

[0148] In an embodiment of the present invention, the preparation electron optical device 102 projects a preparation beam onto the sample 208 prior to evaluation to charge contacts in the sample 208 that have poor electrical connections to the sample 208 (which may be referred to as bad contacts). During or shortly after flooding, for example, between a preparation position where the preparation electron optical device 102 projects (e.g., floods) the preparation beam onto the sample 208 and an evaluation position where the evaluation electron optical device 106 evaluates the sample 208, the sample 208 may be irradiated with a beam 71 suitable for ACC. This can help ensure that contacts that are in acoustic electrical connection (which may be referred to as good contacts) are not charged.

[0149] In one embodiment, light source 70 projects light beam 71 in preparation electron optics 102 or along a path between the preparation position and the evaluation position of sample 208. During evaluation (e.g., inspection), bad contacts are also charged with charge from the evaluation electron beam from evaluation electron optics 106, as are good contacts connected as reverse diodes.

[0150] In one embodiment, the light source 70 is configured to project the light beam 71 toward the sample at an illumination position remote from the evaluation position. The size of the evaluation electron optics 106 relative to the sample 208 does not prevent the use of the light beam 71.

[0151] In one embodiment, the light source 70 is configured to project a beam of light towards the irradiation location before the evaluation charged particle optics 106 projects the evaluation charged particle beam towards the evaluation location to evaluate the sample 208 at the evaluation location.

[0152] In one embodiment, the preliminary charged particle optical device 102 is configured to project the preliminary charged particle beam 302 while the light source 70 projects the light beam 71 toward the irradiation position. The projection of the preliminary electron beam and the projection of the light beam 71 can be performed in parallel. Alternatively, one can be performed after the other, or their time periods can partially overlap each other.

[0153] In one embodiment, the preliminary charged particle optical device 102 is configured to project a preliminary charged particle beam towards the irradiation location. In one embodiment, the light source 70 is configured to project a light beam 71 towards the irradiation location after the preliminary charged particle optical device 102 projects the preliminary charged particle beam.

[0154] In one embodiment, the irradiation position is remote from the evaluation beam path. In one embodiment, the preliminary charged particle optics 102 is configured to project a preliminary charged particle beam along the preliminary beam path towards the preparation position. The preparation position may be the same as or different from the irradiation position.

[0155] In one embodiment, the irradiation position is between the preparation position and the evaluation position. In one embodiment, the distance between the irradiation position and the preparation position is less than the distance between the irradiation position and the evaluation position. In one embodiment, the distance between the irradiation position and the evaluation charged particle optical device 106 is greater than the distance between the evaluation position and the evaluation charged particle optical device 106. In one embodiment, the distance between the evaluation position and the evaluation charged particle optical device 106 in the direction along the evaluation beam path is less than the distance between the irradiation position and the preparation charged particle optical device 102 in the direction along the evaluation beam path. In one embodiment, the distance between the evaluation position and the evaluation charged particle optical device 106 in the direction along the evaluation beam path is less than the distance between the evaluation position and the preparation charged particle optical device 102 in the direction along the evaluation beam path. In one embodiment, the distance between the evaluation position and the evaluation charged particle optical device 106 is less than the distance between the irradiation position and the evaluation charged particle optical device 106 in the direction along the evaluation beam path position.

[0156] In one embodiment, the evaluation position is in the sample plane and the illumination position is in the sample plane. Alternatively, they may be in different planes. In one embodiment, the illumination position is desirably displaced further than the evaluation position in the direction along the evaluation beam path relative to an evaluation charged particle optical device such as an electron source and / or relative to the light source 70.

[0157] In one embodiment, the light source 70 is associated with the preliminary charged particle optical device 102. In one embodiment, the light source 70 is integrated with the preliminary charged particle optical device 102. In one embodiment, the light source is configured such that at least a portion of the beam path along which the light beam is projected is parallel to the direction of the preliminary beam path. In one embodiment, the light source is configured such that at least a portion of the beam path along which the light beam is projected is along at least a portion of the preliminary beam path.

[0158] Alternatively, in one embodiment, the light source is associated with the evaluation charged particle optical device. In one embodiment, the light source is configured to project a light beam when the sample approaches the evaluation position. For example, the irradiation position is along a path of stage movement (e.g., sample movement) from the preparation position to the evaluation position (such as approaching the evaluation location (or evaluation position)). The irradiation position can be when the sample moves within the footprint to the evaluation charged particle device 106, such as, for example, as a beam grid moves into the path of the evaluation beam.

[0159] In one embodiment, the irradiation position is further downward along the evaluation beam path from the evaluation position. In this arrangement, the distance between the evaluation charged particle device and the sample can be greater than the distance during the evaluation. Having the stage lower than the evaluation time during irradiation can ensure that the irradiation of the sample is more effective. When the actuable stage 209 is lowered, the actuable stage 209 can be moved to and / or from a preparation position, such as from an evaluation position, as described in WO 2022128392 A1, the disclosure of which is incorporated herein by reference. In different embodiments, the actuable stage 209 can be moved (e.g., lowered) in a direction along the evaluation beam path, such as at a position between the evaluation position and the preparation position.

[0160] In one embodiment, the actuable stage 209 includes a long-stroke stage and a short-stroke stage that can be actuated independently. The maximum range of motion of the long-stroke stage is longer than the maximum range of motion of the short-stroke stage. In one embodiment, the short-stroke stage is supported by the long-stroke stage. The movement of the long-stroke stage can cause a corresponding movement of the short-stroke stage without any actuation of the short-stroke stage. The long-stroke stage can be configured to provide relatively rough position control over a relatively long distance (i.e., for long movements). The short-stroke stage can be configured to provide more refined position control over a shorter distance. In one embodiment, the range of motion provided by the short-stroke stage can be 1 mm or less, i.e., the displacement size relative to the position of the long-stroke stage is 0.5 mm or less. The actuation of the long stroke can be used to achieve the movement of the sample 208 in the direction along the evaluation beam path, for example, when moving from the evaluation position to the preparation position. When the sample 208 is actuated back to the evaluation position, the actuation of the long stroke can be used to raise the sample 208.

[0161] During a long movement of the stage (e.g., by a long stroke stage), for example between a preparation position and within the coverage area of ​​the evaluation charged particle device, it may be desirable to have the irradiation position (position) (or irradiation location) at a plane away from the evaluation charged particle device along the evaluation beam path so that the gap between the evaluation charged particle device and the sample is larger than the gap between the evaluation charged particle device and the sample during evaluation. Such a larger gap during a long movement contributes to undesirable collisions between the stage and / or the sample and the evaluation charged particle device. The irradiation position can be desirably positioned along the long movement between the preparation position and the evaluation position.

[0162] As another alternative, in one embodiment the light source is included in the illumination device between the evaluation charged particle device and the preparation charged particle device. In one embodiment the illumination device is separate from the evaluation charged particle optical device and the preparation charged particle optical device.

[0163] In one embodiment, the preliminary charged particle optics 102 is a flood charged particle optics for flooding a sample surface with charged particles.

[0164] In one embodiment, the evaluation charged particle optical device and / or the preparation charged particle optical device comprises one or more charged particle optical elements comprising micro-electromechanical components (MEMS components).In one embodiment, the evaluation charged particle beam is a beam grid of a plurality of beams.

[0165] In one embodiment, the surface of the evaluation charged-particle optical device 106 configured to face the evaluation location is a detector array.

[0166] In one embodiment, the charged particle optical apparatus comprises a controller configured to control one or more of the evaluation charged particle optical device, the preparation charged particle optical device and the light source.

[0167] In one embodiment, the charged particle optical device comprises an actuatable stage 209 configured to support the sample 208. In one embodiment, the actuatable stage 209 is configured to move the sample from an illumination position to an evaluation position. Fig.11 , the movement of the actuatable stage 209 between the irradiation position and the evaluation position is indicated by the double-ended arrow 108. In one embodiment, the actuatable stage 209 is configured to move the sample from the irradiation position to the evaluation position after the light source has projected the light beam toward the irradiation position. In one embodiment, the actuatable stage is configured to move the sample to the evaluation position before the evaluation charged particle optical device is configured to project the evaluation charged particle beam toward the evaluation position. In one embodiment, the actuatable stage is configured to move the sample to the irradiation position before the evaluation charged particle optical device is configured to project the evaluation charged particle beam toward the evaluation position.

[0168] In one embodiment, the electron optical device 40 includes a plurality of electron optical devices as shown in the figure as a multi-column device, such as at least Figure 3 and Figure 4 , subject to the following description. Such a multi-column device may include a plurality of electron optical columns arranged in an array such as a rectangular or hexagonal pattern. Each column of the multi-column device may have a Figure 3 Alternatively, the multi-pillar device may include a plurality of pillars arranged in an array, for example, having a regular pattern, and the pillars are included in Figure 4 Shown and referenced in Figure 4 The features and functions of the electron-optical device 41 described are subject to the following differences. Such differences include having a collimator array, for example integrating the collimating deflectors into an objective array assembly, which is, for example, associated with the aperture of the beamlet forming array 252, preferably immediately downstream thereof. Each collimating deflector is assigned to a corresponding beamlet in the multi-beam. The difference may include an array of scanning deflectors integrated into an objective array component, for example associated with the objective array 241. Having an array of scanning deflectors and a collimator array is beneficial because such devices are electrostatic rather than magnetic. Electron-optical column structures having magnetic devices are difficult to integrate into multi-column structures due to interference of the magnetic devices with surrounding columns of the multi-column structure.

[0169] In one embodiment, a method for evaluating a sample 208 is provided. In one embodiment, the method includes projecting a preliminary charged particle beam along a preliminary beam path with a preliminary charged particle optical device, the preliminary charged particle beam being used to prepare the sample for evaluation. In one embodiment, the method includes projecting a beam toward a sample at an irradiation position. In one embodiment, the method includes projecting an evaluation charged particle beam along an evaluation beam path toward a sample at an evaluation position with an evaluation charged particle optical device, the evaluation charged particle beam being used to evaluate the sample at the evaluation position. In one embodiment, the positional relationship between the irradiation position and the evaluation charged particle optical device is different from the positional relationship between the evaluation position and the evaluation charged particle optical device.

[0170] In one embodiment, a method for evaluating a sample 208 is provided. In one embodiment, the method includes projecting a preliminary charged particle beam along a preliminary beam path with a preliminary charged particle optical device, the preliminary charged particle beam being used to prepare the sample for evaluation. In one embodiment, the method includes projecting a light beam toward a sample at an irradiation position. In one embodiment, the method includes projecting an evaluation charged particle beam along an evaluation beam path toward a sample at an evaluation position with an evaluation charged particle optical device, the evaluation charged particle beam being used to evaluate the sample at the evaluation position. In one embodiment, a light beam is projected toward the sample at the irradiation position when the sample is away from the evaluation position.

[0171] In one embodiment, before the evaluation charged particle optical device projects the evaluation charged particle beam toward the evaluation position, a light beam is projected toward the irradiation position. In one embodiment, while the light beam is projected toward the irradiation position, the preliminary charged particle optical device projects the preliminary charged particle beam toward the sample. In one embodiment, as the preliminary charged particle beam is projected toward the sample, the light beam is projected toward the sample.

[0172] In one embodiment, the beam is projected towards the sample after stopping the projection of the preliminary beam towards the sample. In one embodiment, the beam is projected towards the sample after starting the projection of the preliminary charged particle beam towards the sample.

[0173] like Fig.11 As shown, in one embodiment, the light source 70 is configured to project a light beam 71 toward the sample 208 in a gap between the flood rod of the preparation electron optical device 102 and the sample 208. In one embodiment, the method includes moving the sample from the illumination position to the evaluation position using the actuatable stage after the light beam has been projected toward the sample.

[0174] It is not necessary that the light beam 71 is projected through the gap between the flood column and the sample 208. Additionally or alternatively, the light beam 71 can be projected downward along the flood column. The light beam can be guided along the electron optical axis 304, such as through the electron optical components of the flood column (e.g., through one or more of the charged particle source 301, the converging lens 320, the blanking electrode 330, the objective lens 340, and the aperture body 350), such as along or adjacent to the path of the preliminary charged particle beam through the flood column. The light source 70 can be located near the charged particle source 301. In one embodiment, the light beam 71 can be projected from a position (e.g., the light source 70) positioned along the path of the preliminary charged particle beam between the charged particle source 301 of the flood column and the sample, such as from a component of the flood column along the path of the charged particle beam. Such components can be the converging lens 320, the blanking electrode 330, the objective lens 340, and the aperture body 350.

[0175] Additionally or alternatively, light beam 71 may be projected toward sample 208 at a location between the flood column and preparatory electron optics 106 . Fig.12 is a schematic diagram of such an electro-optical device. Fig.12 An actuable stage 209 is shown at an intermediate position between the preparation electron optical device 102 and the evaluation electron optical device 106. The intermediate position may be between the evaluation position and the preparation position. In the intermediate position, the actuable platform 209 or even the sample 208 may be partially located under the footprint of the flood column of the electron optical device 40 or the footprint of the electron optical device 41. In such an intermediate position, the light beam 71 may be angled to illuminate at least a portion of the sample. The light source 70 may be located between the preparation electron optical device 102 and the evaluation electron optical device 106. In one embodiment, the light source 70 is configured to project the light beam 71 toward the sample 208 during the movement of the sample 208. When the light beam 71 is projected toward the sample 208, the sample 208 may not need to be stopped. The light beam may scan at least a portion of the sample. Alternatively, the actuable stage 209 may be configured to stop the sample 208 at an intermediate position when the light source 70 projects the light beam 71 toward the sample 208.

[0176] Fig.13 Schematic diagram of the evaluation electron optical device 106. Fig.13As shown, in one embodiment, before the actuable stage 209 is moved back below the evaluation electron optical device 106 and is raised, a light beam 71 is projected toward the sample 208. The light beam 71 is provided before the evaluation process. The light source 70 can be positioned adjacent to the electron optical device 41. In one embodiment, the irradiation position is in a plane different from the evaluation position along the direction of the evaluation beam path, wherein when the sample is moved between the evaluation position and the irradiation position, it is desired to move the sample between different planes of the irradiation position and the evaluation position. In one embodiment, the actuable stage 209 is configured to move the sample 208 from below the preparation electron optical device 102 (e.g., from the preparation position) to below the evaluation electron optical device 106 (e.g., to the evaluation position) in a plane. The plane is different from (e.g., lower than) the plane of the evaluation position. The sample can be moved between the preparation position and the evaluation position, such as on a plane further below the evaluation beam path. The light source 70 is configured to project a light beam 71 toward the sample 208 when the sample 208 is in a lower plane. This allows space for the light beam 71 to reach the sample 208. The actuatable stage 209 is configured for subsequently moving the sample 208 between these planes to an evaluation position where the sample 208 can be evaluated (eg, inspected).

[0177] The path of the light beam 71 can be angled relative to the orthogonal and / or evaluation beam path direction of the surface of the sample 208. The position of the sample 208 can be illuminated by the light beam 71 when and / or when the sample 208 moves to, for example, below the footprint of the changed particle device 41; for example, before the sample 208 is actuated upward toward the evaluation position (for example, in a plane further above the evaluation beam path). Alternatively, if the gap between the sample 208 and the facing surface of the electron-optical device 41 is large enough, at least a portion of the sample 208 is illuminated by the light beam when the sample 208 is actuated to the evaluation position along the evaluation beam path. In one embodiment, the beam path can be orthogonal to the surface of the sample 208 and / or in a direction parallel to the evaluation beam path. The light beam 71 (for example, at an intermediate position) can be incident on the sample 208 when the sample 208 moves toward the evaluation position, for example, before the sample 208 moves along the beam path toward the sample position. The intermediate position can be adjacent to the electron-optical device 41, for example, incorporated into the electron-optical device 41. Light source 70 may be adjacent to electron-optical device 41, or even incorporated into, for example, integrated into, such as a support feature of electron-optical device 41. In one embodiment, at least a portion of sample 208 illuminated by light beam 71 is beneath the footprint of electron-optical device 41, for example.

[0178] In one embodiment, a method for evaluating a sample 208 is provided. In one embodiment, the method includes projecting a preliminary charged particle beam toward the sample to prepare the sample for evaluation. In one embodiment, the method includes projecting a light beam toward the sample. In one embodiment, the method includes projecting an evaluation charged particle beam toward the sample at an evaluation position along an evaluation beam path for evaluating the sample at the evaluation position. In one embodiment, the projection of the light beam is before the sample evaluation position.

[0179] Although this article mainly focuses on Figures 3 to 5 The present invention is described in any of the depicted and described evaluation charged particle devices 106, but the present invention can be applied to charged particle systems having a single beam device or a multi-beam device, which has a common single magnetic objective lens as the evaluation charged particle device. Such a multi-beam device can have a magnetic converging lens, such as an array of one or more electron optical elements between the converging lens and the objective lens, and a secondary column including a detector array for detecting multiple beams of charged particles from the sample. The Wien filter above the objective lens can separate the charged particles from the sample in response to multiple beams from the multiple beams of charged particles directed to the sample.

[0180] In one embodiment, the method is used to evaluate a sample 208 performing a voltage contrast measurement (ie, through an evaluation process). Suitable apparatus and related methods for such illumination of a sample and / or for such voltage contrast measurement are disclosed and described herein.

[0181] The components or systems mentioned as being controllable to manipulate the components or elements of the electron beam in a certain manner include: configuring a controller or control system or control unit to control the component to manipulate the electron beam in the manner described, and optionally using other controllers or devices (such as voltage sources and / or current sources) to control the component to manipulate the electron beam in this manner. For example, the voltage source can be electrically connected to one or more components under the control of the controller or control system or control unit to apply an electric potential to the component, and the one or more components are listed in a non-limiting manner such as control lens array 250, objective lens array 241, convergence lens 231, corrector, collimator element array and scanning deflector array. One or more controllers, control systems or control units can be used to control an actuatable component (such as a stage) to actuate and thereby move relative to another component (such as a beam path) to control the actuation of the component.

[0182] The embodiments described herein may take the form of a series of aperture arrays or electron optical elements arranged in an array along a beam or multi-beam path. Such electron optical elements may be electrostatic. In one embodiment, all electron optical elements (e.g., the last electron optical element in the beam path from the beam-limiting aperture array to the sample) may be electrostatic and / or may be in the form of an aperture array or plate array. In some arrangements, one or more electron optical elements are manufactured as a micro-electromechanical system (MEMS) (i.e., using MEMS manufacturing techniques).

[0183] References to up and down, upward and downward, above and below, etc. should be understood to refer to directions parallel (usually but not always vertical) to the upstream and downstream directions of the charged particle beam impinging on the sample 208. Thus, references to upstream and downstream are intended to refer to directions about the beam path that are independent of any present gravitational field.

[0184] An electron optical device according to an embodiment of the present disclosure may be a tool for performing a qualitative assessment of a sample (e.g., pass / fail), a tool for performing a quantitative measurement of a sample (e.g., the size of a feature), or a tool for generating a mapped image of a sample. Examples of evaluation systems are inspection tools (e.g., for identifying defects), review tools (e.g., for classifying defects), and metrology tools, or a tool capable of performing any combination of evaluation functions associated with an inspection tool, review tool, or metrology tool (e.g., a metrology inspection tool). The electron optical column may be a component of an evaluation system; for example, an inspection tool or a metrology inspection tool, or part of an electron beam lithography tool. Any reference to a tool herein is intended to encompass an apparatus, device, or system comprising multiple components that may or may not be co-located, and may even be located in separate apertures, particularly, for example, for data processing elements.

[0185] The terms "beamlet" and "beamlet" are used interchangeably herein and are understood to include any radiation beam derived from a parent radiation beam by dividing or splitting the parent radiation beam. The term "manipulator" is used to include any element that affects the path of a beamlet or beamlet, such as a lens or deflector.

[0186] Reference to elements being aligned along the beam path or beamlet path is understood to mean that the respective element is positioned along the beam path or beamlet path.

[0187] Although the present invention has been described in conjunction with various embodiments, other embodiments of the present invention will be apparent to those skilled in the art through consideration of the specification and practice of the invention disclosed herein. The specification and embodiments are considered to be exemplary only, and the true scope and spirit of the present invention are indicated by the appended claims and clauses.

[0188] The above description is intended to be illustrative rather than limiting. Therefore, it will be apparent to those skilled in the art that modifications may be made as described without departing from the scope of the claims and the terms of the present disclosure.

[0189] With the following terms:

[0190] Item 1. A charged particle optical device for evaluating a sample at an evaluation position, the charged particle optical device comprising: an evaluation charged particle optical device configured to project an evaluation charged particle beam along an evaluation beam path toward the evaluation position, the evaluation charged particle beam being used to evaluate the sample at the evaluation position; a preparation charged particle optical device configured to project a preparation charged particle beam along a preparation beam path, the preparation charged particle beam being used to prepare the sample for evaluation; and a light source configured to project a light beam toward an irradiation position; wherein the positional relationship between the irradiation position and the evaluation charged particle optical device is different from the positional relationship between the evaluation position and the evaluation charged particle optical device.

[0191] Item 2. A charged particle optical device for evaluating a sample at an evaluation position, the charged particle optical device comprising: an evaluation charged particle optical device configured to project an evaluation charged particle beam along an evaluation beam path toward the evaluation position, the evaluation charged particle beam being used to evaluate the sample at the evaluation position; a preparation charged particle optical device configured to project a preparation charged particle beam along a preparation beam path, the preparation beam being used to prepare the sample for evaluation; and a light source configured to project a light beam toward the sample at an irradiation position away from the evaluation position, desirably so that the sample is positioned away from the evaluation position when the sample is at the irradiation system.

[0192] Item 3. A charged particle optical device according to Item 1 or 2, wherein the light source is configured to project the evaluation charged particle beam toward the irradiation position before the evaluation charged particle optical device projects the evaluation charged particle beam toward the evaluation position for evaluating the sample at the evaluation position.

[0193] Clause 4. A charged particle optical apparatus according to clause 1, 2 or 3, wherein the preliminary charged particle optical device is configured to project the preliminary charged particle beam when the light source projects the light beam towards the irradiation position.

[0194] Clause 5. Charged particle optical apparatus according to any of the preceding clauses, wherein the preliminary charged particle optical device is configured to project the preliminary charged particle beam towards the irradiation location.

[0195] Clause 6. A charged particle optical apparatus according to any of the preceding clauses, wherein the light source is configured to project the beam towards the irradiation location after the preliminary charged particle optical device projects the preliminary charged particle beam.

[0196] Clause 7. A charged particle optical apparatus according to any of the preceding clauses, wherein the illumination position is displaced away from the evaluation beam path.

[0197] Clause 8. Charged particle optical apparatus according to any of the preceding clauses, wherein the preliminary charged particle optical device is configured to project the preliminary charged particle beam along the preliminary beam path towards a preparation position.

[0198] Clause 9. The charged particle optical device of Clause 8, wherein the irradiation position is between the preparation position and the evaluation position.

[0199] Clause 10. A charged particle optical device according to any one of clauses 8 or 9, wherein a distance between the irradiation position and the preparation position is smaller than a distance between the irradiation position and the evaluation position.

[0200] Clause 11. Charged particle optical apparatus according to any of the preceding clauses, wherein a distance between the illumination position and the evaluation charged particle optical device is greater than a distance between the evaluation position and the evaluation charged particle optical device.

[0201] Item 12. A charged particle optical device according to any of the preceding items, wherein the distance between the evaluation position and the evaluation charged particle optical device in the direction along the evaluation beam path is smaller than the distance between the irradiation position and the preparation charged particle optical device in the direction along the evaluation beam path.

[0202] Clause 13. A charged particle optical device according to any of the preceding clauses, wherein the distance between the evaluation position and the evaluation charged particle optical device in the direction along the evaluation beam path is smaller than the distance between the evaluation position and the preparation charged particle optical device in the direction along the evaluation beam path.

[0203] Clause 14. A charged particle optical device according to any of the preceding clauses, wherein the distance between the evaluation position and the evaluation charged particle optical device in the direction along the evaluation beam path position is smaller than the distance between the irradiation position and the evaluation charged particle optical device.

[0204] Item 15. A charged particle optical device according to any of the preceding items, wherein the field of view of the evaluation charged particle optical device at the evaluation position in a direction intersecting the evaluation beam path is wider than the distance between the evaluation position and the evaluation charged particle optical device in a direction along the evaluation beam path.

[0205] Clause 16. A charged particle optical device according to any of the preceding clauses, wherein the preparation portion is the surface of the sample prepared by the preparation beam, and the evaluation portion is the surface of the sample evaluated by the evaluation beam at the evaluation position, wherein the preparation portion is at least as large as the evaluation portion, preferably wherein the preparation portion surrounds the evaluation portion, and preferably wherein the preparation portion includes the preparation portion.

[0206] Clause 17. Charged particle optical apparatus according to Clause 16, wherein the preparation portion corresponds to the field of view of the preparation beam and the evaluation portion corresponds to the field of view of the evaluation beam at the evaluation position.

[0207] Clause 18. A charged particle optical apparatus according to any of the preceding clauses, wherein the evaluation position is in a sample plane and the illumination position is in the sample plane.

[0208] Clause 19. Charged particle optical apparatus according to any of clauses 1 to 17, wherein the illumination position is displaced further than the evaluation position in a direction along the evaluation beam path, desirably displaced relative to the evaluation charged particle optical device.

[0209] Clause 20. Charged particle optical apparatus according to any of the preceding clauses, wherein the light source is associated with the preliminary charged particle optical device.

[0210] Clause 21. The charged particle optical apparatus of Clause 20, wherein the light source is integrated with the preliminary charged particle optical device.

[0211] Clause 22. A charged particle optical device according to any of the preceding clauses, wherein the light source is configured such that at least a portion of a beam path along which the light beam is projected is parallel to the direction of the preliminary beam path.

[0212] Clause 23. A charged particle optical device according to any of the preceding clauses, wherein the light source is configured such that at least a portion of the beam path along which the light beam is projected is along at least a portion of the preliminary beam path.

[0213] Clause 24. Charged particle optical apparatus according to any one of clauses 1 to 19, wherein the light source is associated with the evaluation charged particle optical device.

[0214] Clause 25. A charged particle optical device according to clause 24, wherein the light source is configured to project the light beam when the sample is close to the evaluation location.

[0215] Clause 26. Charged particle optical apparatus according to any one of clauses 1 to 19, wherein the light source is included in an illumination device between the evaluation charged particle device and the preparation charged particle device.

[0216] Clause 27. The charged particle optical apparatus according to Clause 26, wherein the illumination device is separate from the evaluation charged particle optical device and the preliminary charged particle optical device.

[0217] Clause 28. A charged particle optics apparatus according to any of the preceding clauses, wherein the preliminary charged particle optics device is a flood charged particle optics apparatus for flooding a sample surface with charged particles.

[0218] Clause 29. A charged particle optical apparatus according to any of the preceding clauses, wherein the evaluation charged particle optical device and / or the preliminary charged particle optical device comprises one or more charged particle optical elements comprising micro-electromechanical components.

[0219] Clause 30. A charged particle optical device according to any of the preceding clauses, wherein the evaluation charged particle beam is a beam grid of a plurality of beams.

[0220] Clause 31. Charged particle optical apparatus according to any of the preceding clauses, wherein a surface of the evaluation charged particle optical device configured to face the evaluation location is an array of electron optical elements, such as a detector array.

[0221] Clause 32. A charged particle optical apparatus according to any of the preceding clauses, comprising a controller configured to control one or more of the evaluation charged particle optical device, the preliminary charged particle optical device and the light source.

[0222] Clause 33. A charged particle optical apparatus according to any of the preceding clauses, further comprising an actuatable stage configured to support the sample.

[0223] Clause 34. A charged particle optical apparatus according to clause 33, wherein the actuatable stage is configured to move the sample from the illumination position to the evaluation position after a light source has projected the light beam towards the illumination position.

[0224] Clause 35. A charged particle optical apparatus according to clause 33 or 34, wherein the actuatable stage is configured to move the sample into the evaluation position before the evaluation charged particle optical device is configured to project the evaluation charged particle beam towards the evaluation position.

[0225] Clause 36. A charged particle optical apparatus according to any one of clauses 33 to 35, wherein the actuatable stage is configured to move the sample to the irradiation position before the evaluation charged particle optical device is configured to project the evaluation charged particle beam towards the evaluation position.

[0226] Item 37. A method for evaluating a sample at an evaluation position, the method comprising: projecting a preliminary charged particle beam along a preliminary beam path using a preliminary charged particle optical device, the preliminary charged particle beam being used to prepare the sample for evaluation; projecting a light beam toward the sample at an irradiation position; and projecting an evaluation charged particle beam along an evaluation beam path toward the sample at the evaluation position using an evaluation charged particle optical device, the evaluation charged particle beam being used to evaluate the sample at the evaluation position; wherein the positional relationship between the irradiation position and the evaluation charged particle optical device is different from the positional relationship between the evaluation position and the evaluation charged particle optical device.

[0227] Item 38. A method for evaluating a sample at an evaluation position, the method comprising: projecting a preliminary charged particle beam along a preliminary beam path using a preliminary charged particle optical device, the preliminary charged particle beam being used to prepare the sample for evaluation; projecting a light beam toward the sample at an irradiation position; and projecting an evaluation charged particle beam along an evaluation beam path toward the sample at the evaluation position using an evaluation charged particle optical device, the evaluation charged particle beam being used to evaluate the sample at the evaluation position; wherein when the sample is away from the evaluation position, the light beam is projected toward the sample at the irradiation position.

[0228] Clause 39. The method of clause 38, wherein the beam is projected towards the irradiation location before the evaluation charged-particle optical device projects the evaluation charged-particle beam towards the evaluation location.

[0229] Clause 40. The method of clause 38 or 39, wherein the preliminary charged particle optical device projects the preliminary charged particle beam towards the sample when projecting the beam towards the irradiation location.

[0230] Clause 41. The method of clause 40, wherein projecting the beam toward the sample begins as the projection of the preliminary charged particle beam toward the sample begins.

[0231] Clause 42. The method of clause 38 or 39, wherein the beam is projected toward the sample after the projection of the preparatory beam toward the sample has ceased.

[0232] Clause 43. The method according to any one of clauses 38 to 42, wherein the projection of the beam towards the sample is started after the start of the projection of the preliminary charged particle beam towards the sample.

[0233] Clause 44. The method of any one of clauses 38 to 43, comprising: after the light beam is projected onto the sample, moving the sample from the illumination position to the evaluation position with an actuatable stage.

[0234] Item 45. A method according to Item 44, wherein the irradiation position and the evaluation position are in different planes along the direction of the evaluation beam path, wherein when the sample is moved between the evaluation position and the irradiation position, it is desired to move the sample between the different planes of the irradiation position and the evaluation position.

[0235] Item 46. A method for evaluating a sample at an evaluation position, the method comprising: projecting a preparatory charged particle beam toward the sample to prepare the sample for evaluation; projecting a light beam toward the sample; and projecting an evaluation charged particle beam along an evaluation beam path toward the sample at the evaluation position to evaluate the sample at the evaluation position, wherein the projecting of the light beam occurs before the sample is at the evaluation position.

[0236] Item 47. A charged particle optical device for evaluating a sample at an evaluation position, the charged particle optical device comprising: an evaluation charged particle optical device configured to project an evaluation charged particle beam along an evaluation beam path toward the evaluation position, the evaluation charged particle beam being used to evaluate the sample at the evaluation position; and a preparation charged particle optical device configured to project a preparation charged particle beam along a preparation beam path, the preparation charged particle beam being used to prepare the sample for evaluation; wherein the evaluation charged particle optical device comprises: one or more charged particle optical elements, the one or more charged particle optical elements comprising micro-electromechanical components and / or objective lenses, the objective lenses comprising multiple objective lenses for evaluating different beams of the charged particle beam.

[0237] Clause 48. A charged particle optical device according to clause 48, wherein the different beams are beamlets. Desirably, the beamlets are derived from the evaluation charged particle beam. Desirably, the different beams are projected toward the sample. Desirably, the objective lens includes one or more charged particle optical elements. Desirably, one or more of the charged particle optical elements include a detector, for example a detector array desirably including an array of detector elements. A detector element can be configured to detect signal particles derived from different beams of the evaluation charged particles from a source of the evaluation charged particle device.

Claims

1. A charged particle optical device for evaluating a sample at an evaluation position, the charged particle optical device comprising: an evaluation charged particle optical device configured to project an evaluation charged particle beam along an evaluation beam path toward an evaluation position, the evaluation charged particle beam being used to evaluate a sample at the evaluation position; preparation charged particle optics configured to project a preparation charged particle beam along a preparation beam path, the preparation beam being used to prepare a sample for evaluation; as well as A light source is configured to project a light beam toward the sample when the sample is positioned at an illumination position away from the evaluation position.

2. The charged particle optical apparatus according to claim 1, wherein the light source is configured to project the light beam toward the irradiation position before the evaluation charged particle optical device projects the evaluation charged particle beam toward the evaluation position for evaluating a sample at the evaluation position. 3 . The charged particle optical apparatus according to claim 1 , wherein the preliminary charged particle optical device is configured to project the preliminary charged particle beam when the light source projects the light beam toward the irradiation position. 4 . The charged particle optical apparatus according to claim 1 , wherein the preliminary charged particle optical device is configured to project the preliminary charged particle beam towards the irradiation location. 5 . The charged particle optical apparatus according to claim 1 , wherein the light source is configured to project the light beam towards the irradiation position after the preliminary charged particle optical device projects the preliminary charged particle beam.

6. Charged particle optical apparatus according to any of the preceding claims, wherein the illumination position is displaced away from the evaluation beam path.

7. A charged particle optical apparatus according to any one of the preceding claims, wherein the preliminary charged particle optical device is configured to project the preliminary charged particle beam along the preliminary beam path towards a preparation position. 8 . The charged particle optical device according to claim 7 , wherein the irradiation position is between the preparation position and the evaluation position.

9. The charged particle optical apparatus according to any one of the preceding claims, wherein the distance between the irradiation position and the evaluation charged particle optical device is greater than the distance between the evaluation position and the evaluation charged particle optical device.

10. A charged particle optical device according to any of the preceding claims, wherein the distance between the evaluation position and the evaluation charged particle optical device in the direction along the evaluation beam path is smaller than the distance between the irradiation position and the preparatory charged particle optical device in the direction along the evaluation beam path.

11. A charged particle optical device according to any of the preceding claims, wherein the distance between the evaluation position and the evaluation charged particle optical device in the direction along the evaluation beam path is smaller than the distance between the evaluation position and the preparation charged particle optical device in the direction along the evaluation beam path.

12. A charged particle optical device according to any one of the preceding claims, wherein the distance between the evaluation position and the evaluation charged particle optical device is smaller than the distance between the irradiation position and the evaluation charged particle optical device in the direction along the evaluation beam path position.

13. A charged particle optical device according to any of the preceding claims, wherein the field of view of the evaluation charged particle optical device at the evaluation position in a direction intersecting the evaluation beam path is wider than the distance between the evaluation position and the evaluation charged particle optical device in a direction along the evaluation beam path.

14. A charged particle optical device according to any one of the preceding claims, wherein the preparation part is the surface of the sample prepared by the preparation beam, and the evaluation part is the surface of the sample evaluated by the evaluation beam at the evaluation position, wherein the preparation part is desirably at least as large as the evaluation part, and wherein the preparation part surrounds the evaluation part.

15. The charged particle optical apparatus according to any one of claims 1, wherein the irradiation position is displaced further than the evaluation position in a direction along the evaluation beam path, desirably relative to the evaluation charged particle optical device.

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