Charged Particle Device Detector

Abstract

A detector for use in a charged particle device for an evaluation tool for detecting signal particles from a sample, the detector comprising a substrate comprising a semiconductor element configured to detect signal particles above a first energy threshold and a charge-based element configured to detect signal particles below a second energy threshold.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to European Patent Application Publication No. 21183811.5, filed July 5, 2021, the entire contents of which are incorporated by reference into this specification.

[0002] Field FIELD OF THE DISCLOSURE

[0002] Embodiments provided herein relate generally to charged particle devices, detectors and methods. [Background technology]

[0003]

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

[0004]

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

[0005]

[0005] Although the data obtained in this way can be useful, there are limitations to the information that can be obtained about a sample from such known electron microscopy techniques. In general, there is a need to obtain additional or alternative information, for example about the structure below the surface of the sample and about overlay targets. Summary of the Invention

[0006] It is an object of the present disclosure to provide embodiments that aid in obtaining information from a sample using charged particles, for example, using backscattered signal particles and / or secondary signal particles.

[0007]

[0007] According to one aspect of the present invention, there is provided a charged particle evaluation tool for evaluation by detecting signal particles from a sample using a charged particle device that projects multiple beams of charged particles towards the sample, the evaluation tool comprising a detector array comprising a plurality of detectors configured to detect signal particles from the sample, the plurality of detectors being provided in a substrate, each detector corresponding to a respective sub-beam, each detector of the substrate comprising a semiconductor element configured to detect signal particles above a first energy threshold and a charge-based element configured to detect signal particles below a second energy threshold.

[0008]

[0008] According to one aspect of the present invention, a detector for use in a charged particle device for an evaluation tool for detecting signal particles from a sample is provided, the detector comprising a substrate comprising a semiconductor element configured to detect signal particles above a first energy threshold and a charge-based element configured to detect signal particles below a second energy threshold.

[0009]

[0009] According to one aspect of the present invention, there is provided a detector array comprising a plurality of detectors as described in the above aspect, the detectors being arranged within a common substrate, each detector corresponding to a respective sub-beam.

[0010]

[0010] According to one aspect of the present invention, there is provided a detector array for use in a multi-beam charged particle device for an evaluation tool for detecting signal particles from a sample, the detector array comprising at least one substrate having a plurality of apertures defined within the substrate for passing a plurality of sub-beams of a charged particle beam towards the sample, the substrate comprising a plurality of semiconductor elements configured to detect signal particles above a first energy threshold and a plurality of charge base elements configured to detect signal particles below a second energy threshold, each semiconductor element associated with a corresponding one of the charged base elements.

[0011]

[0011] According to one aspect of the present invention, a charged particle device for an evaluation tool for detecting signal particles from a sample is provided, the device comprising an objective lens configured to project a beam of charged particles onto the sample and a detector as described in the above aspect.

[0012]

[0012] According to one aspect of the present invention, there is provided a charged particle device for an evaluation tool for detecting signal particles from a sample, the device comprising: an objective lens array configured to project multiple sub-beams of charged particles onto the sample in a multi-beam array, with an aperture defined for each sub-beam; and a detector system comprising at least one detector array as described in the above aspect, with the aperture of the at least one detector array aligned with the aperture defined in the objective lens array.

[0013]

[0013] According to one aspect of the present invention, there is provided a charged particle device for an evaluation tool for detecting charged particles from a sample, the device comprising: an objective lens configured to project a beam of charged particles onto the sample, the objective lens defining an aperture for the beam; a detector adjacent to the sample and defining an aperture aligned with the aperture of the objective lens, the detector comprising a first detector element configured to detect signal particles above a first energy threshold and a second detector element configured to simultaneously detect signal particles below a second energy threshold, the detector comprising a semiconductor element.

[0014]

[0014] According to one aspect of the present invention, there is provided a method for projecting a beam of charged particles onto a sample to detect signal particles emitted from the sample, the method comprising: a) projecting the beam along a primary beam path onto a surface of the sample; and b) simultaneously detecting signal particles emitted from the sample at a semiconductor element and at a charge-based element.

[0015]

[0015] According to one aspect of the present invention, there is provided a method for projecting a beam of charged particles onto a sample to detect signal particles emitted from the sample, the method comprising: a) projecting the beam along a primary beam path onto a surface of the sample; and b) detecting signal particles emitted from the sample at a detector, the detector being adjacent to the sample and comprising a semiconductor element, the detecting including simultaneous detection of signal particles above a first energy threshold at a corresponding first detector element and signal particles below a second energy threshold at a second detector element.

[0016]

[0016] According to one aspect of the present invention, there is provided a method of projecting multiple sub-beams of charged particles onto a sample to detect signal particles emitted from the sample, the method comprising: a) projecting the sub-beams along a main sub-beam path onto a surface of the sample; and b) detecting signal particles emitted from the sample in a detector array, the detector array comprising a detector adjacent to the sample and comprising a semiconductor element corresponding to each sub-beam, the detector comprising a first detector element and a second detector element, the detecting including simultaneous detection by each detector of signal particles above a first energy threshold at the corresponding first detector element and signal particles below a second energy threshold at the second detector element.

[0017]

[0017] According to one aspect of the present invention, there is provided a method for projecting a beam of charged particles onto a sample to detect signal particles emitted from the sample, the method comprising providing a device according to the above aspect, projecting the beam of charged particles onto the sample using an objective lens, and simultaneously detecting the resulting signal particles using a semiconductor element and a charge-based element.

[0018]

[0018] The above and other aspects of the present disclosure will become more apparent from the illustrative embodiments in conjunction with the accompanying drawings. [Brief description of the drawings]

[0019] [Figure 1]FIG. 1 is a schematic diagram illustrating an exemplary charged particle beam inspection apparatus. [Diagram 2]

[0020] 2 is a schematic diagram illustrating an example multi-beam device that is part of the example charged particle beam inspection apparatus of FIG. 1. [Diagram 3]

[0021] 1 is a schematic diagram of an exemplary multi-beam device according to one embodiment. [Figure 4]

[0022] 1 is a schematic cross-sectional view of an objective lens according to an embodiment. [Diagram 5]

[0023] 1 is a schematic diagram of an exemplary charged particle optical device according to an embodiment.

[0024] [Figure 6A]

[0025] 1 shows a bottom view of a variant of the detector; [Figure 6B]

[0025] A bottom view of a variant of the detector is shown. [Figure 7]

[0026] FIG. 2 is a schematic cross-sectional view of an objective lens with detectors at various positions along the beam path. [Figure 8]

[0027] 1 is a schematic diagram of an exemplary charged particle optical system including a macro-collimator and a macro-scanning deflector. [Figure 9]

[0028] 1 is a schematic diagram of an exemplary single beam device according to one embodiment. [Figure 10A]

[0029] 1 is a schematic diagram of a detector array and associated cell array according to one embodiment. [Figure 10B] 2 is a schematic diagram of a cell of a cell array. [Figure 10C] 2 is a schematic diagram of a cell of a cell array according to one embodiment. [Figure 11]

[0030] FIG. 2 is a circuit diagram of another exemplary amplifier circuit in accordance with an embodiment. [Figure 12]

[0031] FIG. 2 is a circuit diagram of another exemplary amplifier circuit in accordance with an embodiment. [Figure 13]

[0032] 2 is a schematic cross-sectional view of a wiring route showing circuit wires and a shielding configuration according to one embodiment. [Figure 14]

[0033] 1 is a cross-sectional view of a detector according to one embodiment. [Figure 15]

[0034] 1 is a cross-sectional view of a detector according to one embodiment. [Figure 16]

[0035] 1 is a cross-sectional view of a detector according to one embodiment. [Figure 17]

[0036] 1 is a cross-sectional view of a detector array according to one embodiment. [Figure 18]

[0037] 18 is a cross-section of a detector array according to a variation of FIG. 17. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020]

[0038] The drawings are schematic diagrams. The schematic diagrams and representations show the components described below. However, the components shown in the drawings are not to scale. The relative dimensions of the components in the drawings are exaggerated for clarity. In the following description of the drawings, the same or similar reference numbers refer to the same or similar components or entities, and only the differences with respect to the individual embodiments are described.

[0021]

[0039] Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings. Unless otherwise indicated, the same numerals in different drawings represent the same or similar elements. The implementations set forth in the following description of the exemplary embodiments do not necessarily represent all implementations consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with aspects related to the present invention recited in the appended claims.

[0022]

[0040] Enhanced computing power of electronic devices, which reduces the physical size of the device, can be achieved by significantly increasing the packing density of circuit components, such as transistors, capacitors, diodes, etc., on an IC chip. This has been made possible by increased resolution, which allows for the creation of smaller structures. For example, a smartphone IC chip, the size of a thumbnail and available in 2019 or earlier, may contain over 20 billion transistors, each smaller than one thousandth the size of a human hair. It is therefore not surprising that semiconductor IC manufacturing is a complex and time-consuming process with hundreds of individual steps. Even an error in one step can have a profound effect on the functionality of the final product. Just one "killer defect" can cause device failure. The objective of the manufacturing process is to improve the overall yield of the process. For example, to obtain a 75% yield for a 50-step process (a step can refer to the number of layers formed on a wafer), the individual steps must have a yield greater than 99.4%. If the individual steps have a yield of 95%, the overall process yield would be as low as 7%.

[0023]

[0041] While high process yields are desirable in IC chip manufacturing facilities, it is also important to maintain high substrate (i.e., wafer) throughput, defined as the number of substrates processed per hour. High process yields and high substrate throughput can be affected by the presence of defects. This is especially true when operator intervention is required to check for defects. Therefore, high throughput detection and identification of micro- and nanoscale defects by inspection tools (e.g., scanning electron microscopes (SEMs)) is essential to maintain high yields and low costs.

[0024]

[0042] The SEM comprises a scanning device and a detector arrangement. The scanning device comprises an illumination arrangement with an electron source for generating primary electrons, and a projection arrangement for scanning a sample, such as a substrate, with one or more focused beams of primary electrons. At least the illumination arrangement or illumination system and the projection arrangement or projection system together can be referred to as an electron optical system or arrangement. The primary electrons interact with the sample to generate secondary electrons. The detector arrangement captures the secondary electrons from the sample as it is scanned, so that the SEM can build up an image of the scanned area of ​​the sample. For high throughput inspection, some inspection apparatuses use multiple focused primary beams of primary electrons, i.e. multibeams. The beams constituting the multibeam may be referred to as sub-beams or beamlets or an array of primary beams. The multibeams can scan different parts of the sample simultaneously. Thus, multibeam inspection apparatuses can inspect samples at much faster speeds than single-beam inspection apparatuses. Implementations of known multibeam inspection apparatuses are described below.

[0025]

[0043] Reference is now made to Figure 1, which is a schematic diagram illustrating an exemplary charged particle beam inspection apparatus 100. The charged particle beam inspection apparatus 100 of Figure 1 includes a main chamber 10, a load lock chamber 20, a charged particle beam tool 40 (or sometimes referred to as an electron beam tool), an equipment front end module (EFEM) 30, and a controller 50. The charged particle beam tool 40 is located within the main chamber 10.

[0026]

[0044] The EFEM 30 includes a first load port 30a and a second load port 30b. The EFEM 30 may include additional load ports. The first load port 30a and the second load port 30b may accommodate, for example, a substrate (e.g., a semiconductor substrate, or a substrate made of other materials) to be inspected, or a front opening integrated pod (FOUP) for substrates containing specimens (wafers and specimens hereafter collectively referred to as "specimens"). One or more robotic arms (not shown) in the EFEM 30 transport the specimens to the load lock chamber 20.

[0027]

[0045] The load lock chamber 20 is used to remove gases around the sample. This creates a vacuum, which is a local gas pressure lower than the pressure of the surrounding environment. The load lock chamber 20 may be connected to a load lock vacuum pumping system (not shown), which removes gas particles in the load lock chamber 20. The operation of the load lock vacuum pumping system allows the load lock chamber to reach a first pressure below atmospheric pressure. After the first pressure is reached, one or more robot arms (not shown) transport the sample from the load lock chamber 20 to the main chamber 10. The main chamber 10 is connected to a main chamber vacuum pumping system (not shown). The main chamber vacuum pumping 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 the second pressure is reached, the sample is transported to a charged particle beam tool 40, where the sample can be inspected. The charged particle beam tool 40 may comprise a multi-beam charged particle optical device.

[0028]

[0046] The controller 50 is electronically connected to the charged particle beam tool 40. The controller 50 may be a processor (e.g., a computer) configured to control the charged particle beam inspection apparatus 100. The controller 50 may also include processing circuitry configured to perform various signal and image processing. Although the controller 50 is shown in FIG. 1 as being external to the structure including the main chamber 10, the load lock chamber 20, and the EFEM 30, it is understood that the controller 50 may be part of that structure. The controller 50 may be located in one of the components of the charged particle beam inspection apparatus or distributed across at least two of the components. While the present disclosure provides an example of a main chamber 10 housing a charged particle beam inspection tool, it should be noted that aspects of the present disclosure, in its broadest sense, are not limited to a chamber housing a charged particle beam inspection tool. Rather, it is understood that the principles discussed above may also be applied to tools and other configurations of the apparatus operating under a second pressure.

[0029]

[0047] Reference is now made to Figure 2, which is a schematic diagram illustrating an exemplary charged particle beam tool 40 including a multi-beam inspection tool that is part of the exemplary charged particle beam inspection apparatus 100 of Figure 1. The multi-beam charged particle beam tool 40 (also referred to herein as apparatus 40) comprises a charged particle source 201, a projection apparatus 230, a motorized stage 209 (or a moving stage), and a sample holder 207. The charged particle source 201 and the projection apparatus 230 together may be referred to as an illumination apparatus. The sample holder 207 is supported by the motorized stage 209 to hold a sample 208 (e.g., a substrate or a mask) for inspection. The multi-beam charged particle beam tool 40 further comprises a detector array 240 (e.g., an electronic detection device).

[0030]

[0048] The controller 50 may be connected to various parts of the charged particle beam inspection apparatus 100 of FIG. 1. The controller 50 may be connected to various parts of the charged particle beam tool 40 of FIG. 2, such as the charged particle source 201, the detector array 240, the projection device 230, and the motorized stage 209. The controller 50 may perform various data, image and / or signal processing functions. The controller 50 may also generate various control signals to manage the operation of the charged particle beam inspection apparatus 100, including the charged particle multi-beam device. The controller 50 may control the motorized stage 209 to move the sample 208 during inspection of the sample 208. The controller 50 may enable the motorized stage 209 to move the sample 208 in a direction, preferably continuously, for example at a constant speed, at least during inspection of the sample. The controller 50 may control the movement of the motorized stage 209 such that the motorized stage 209 varies the speed of movement of the sample 208 depending on various parameters. For example, the controller 50 may control the stage velocity (including its direction) in response to the characteristics of the inspection step of the scanning process.

[0031]

[0049] The charged particle source 201 may comprise a cathode (not shown) and an extractor or anode (not shown). In operation, the charged particle source 201 is configured to emit charged particles (e.g., electrons) as primary charged particles from the cathode. The primary charged particles are extracted or accelerated by the extractor and / or anode to form a primary charged particle beam 202. The charged particle source 201 may comprise multiple sources as described in EP 20184161.6, which is incorporated herein by reference at least with respect to the multiple sources and how they relate to multiple columns and their associated charged particle optics.

[0032]

[0050] The projection device 230 is configured to convert the primary charged particle beam 202 into a number of sub-beams 211, 212, 213 and direct each sub-beam onto the sample 208. Although three sub-beams are shown for simplicity, there may be tens, hundreds or thousands of sub-beams. The sub-beams may be referred to as beamlets. Furthermore, although this specification and drawings relate to a multi-beam system, a single-beam system may instead be used, in which case the primary charged particle beam 202 is not converted into a number of sub-beams. This is explained further below in relation to FIG. 9, but it should be noted that the sub-beams may be interchangeable with the single primary charged particle beam 202.

[0033]

[0051] The projection device 230 may be configured to focus the sub-beams 211, 212, and 213 onto the sample 208 for inspection, and form three probe spots 221, 222, and 223 on the surface of the sample 208. The projection device 230 may be configured to deflect the primary sub-beams 211, 212, and 213 to scan the probe spots 221, 222, and 223 over respective scan areas on a section of the surface of the sample 208. In response to the incidence of the primary sub-beams 211, 212, and 213 on the probe spots 221, 222, and 223 on the sample 208, signal charged particles (e.g., electrons), including secondary signal particles and backscattered signal particles, are generated (i.e., emitted) from the sample 208. The signal particles emitted from the sample, e.g., secondary electrons and backscattered electrons, may alternatively be referred to as charged particles, e.g., secondary charged particles and backscattered charged particles. The signal beam is formed of the signal particles emitted from the sample. It will generally be 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 primary beam) or will have at least one directional component opposite to the direction of the primary beam. The signal particles emitted by the sample 208 may also pass through the electrodes of the objective lens and will be subjected to an electric field.

[0034]

[0052] Secondary signal particles typically have a charged particle energy of 50 eV or less. While actual secondary signal particles can have energies less than 5 eV, anything less than 50 eV is usually considered a secondary signal particle. Backscattered signal particles typically have energies between 0 eV and the landing energy of the primary sub-beams 211, 212, and 213. Signal particles detected with energies less than 50 eV are usually considered secondary signal particles, so that a portion of the actual backscattered signal particles will be counted as secondary signal particles. Secondary signal particles may be more specifically referred to as secondary electrons and are interchangeable with secondary electrons. Backscattered signal particles may be more specifically referred to as backscattered electrons and are interchangeable with backscattered electrons. Those skilled in the art will understand that backscattered signal particles may be more generally described as secondary signal particles. However, for purposes of this disclosure, backscattered signal particles are considered to be different from secondary signal particles, e.g., to have higher energy. In other words, secondary signal particles are understood to be particles that have a kinetic energy of 50 eV or less when emitted from the sample, and backscattered signal particles are understood to be particles that have a kinetic energy higher than 50 eV when emitted from the sample. In practice, signal particles may be accelerated before being detected, and therefore the energy range associated with the signal particles may be slightly higher. For example, secondary signal particles are understood to be particles that have a kinetic energy of 200 eV or less when detected at the detector, and backscattered signal particles are understood to be particles that have a kinetic energy higher than 200 eV when detected at the detector. It should be noted that the value of 200 eV may vary depending on the degree of acceleration of the particles, and may be, for example, about 100 eV or 300 eV. Secondary signal particles with such values ​​are still considered to have a sufficient energy different from backscattered signal particles.

[0035]

[0053] The detector array 240 is configured to detect (i.e. capture) signal particles emitted from the sample 208. The detector array 240 is configured to generate a corresponding signal, which is transmitted to a signal processing system 280 to construct, for example, an image of a corresponding scanned area of ​​the sample 208. The detector array 240 may be integrated within the projection device 230. The detector array may alternatively be referred to as a sensor array, and the terms "detector" and "sensor" and "sensor unit" are used interchangeably throughout this specification.

[0036]

[0054] The signal processing system 280 may comprise circuitry (not shown) configured to process signals from the detector array 240 to form an image. The signal processing system 280 may alternatively be referred to as an image processing system or a data processing system. The signal processing system may be incorporated into a component of the multi-beam charged particle beam tool 40, such as the detector array 240 (as shown in FIG. 2). However, the signal processing system 280 may be incorporated into any component of the inspection apparatus 100 or the multi-beam charged particle beam tool 40, such as part of the projection apparatus 230 or the controller 50. The signal processing system 280 may be located outside the structure including the main chamber shown in FIG. 1. The signal processing system 280 may comprise an image acquirer (not shown) and a storage device (not shown). For example, the signal processing system may comprise a processor, a computer, a server, a mainframe host, a terminal, a personal computer, any type of mobile computing device, etc., or a combination thereof. The image acquirer may comprise at least a portion of the processing functionality of the controller. Thus, the image acquirer may comprise at least one or more processors. The image acquirer may be communicatively coupled to the detector array 240 to enable signal communication, such as via electrical conductors, fiber optic cables, portable storage media, IR, Bluetooth, Internet, wireless networks, wireless radios, or combinations thereof, among others. The image acquirer may receive signals from the detector array 240, process data contained in the signals, and construct an image from the data. Thus, the image acquirer may acquire an image of the sample 208. The image acquirer may also perform various post-processing functions, such as generating contours, overlaying indicators on the acquired image, etc. The image acquirer may be configured to perform adjustments, such as brightness and contrast, of the acquired image. The storage device may be a storage medium, such as a hard disk, a flash drive, cloud storage, random access memory (RAM), other types of computer-readable memory, etc.A storage device may be coupled to the image acquirer and may be used to store raw scanned image data as original images, and post-processed images.

[0037]

[0055] The signal processing system 280 may include measurement circuitry (e.g., an analog-to-digital converter) for obtaining a distribution of detected secondary signal particles. The electron distribution data collected during the detection time window can be used in combination with the corresponding scan path data of each of the primary sub-beams 211, 212 and 213 incident on the sample surface to reconstruct an image of the inspected sample structure. The reconstructed image can be used to reveal various features of the internal or external structure of the sample 208. Thus, the reconstructed image can be used to reveal any defects that may be present in the sample.

[0038]

[0056] Known multi-beam systems, such as the charged particle beam tool 40 and charged particle beam inspection apparatus 100 described above, are disclosed in U.S. Patent Application Publication Nos. 2020118784, 20200203116, 2019 / 0259570, and 2019 / 0259564, which are incorporated herein by reference.

[0039]

[0057] In known single beam systems, theoretically different signals may be detected (e.g., from secondary signal particles and / or backscattered signal particles). Multi-beam systems are known and useful because they provide much greater throughput than using a single beam system, for example, the throughput of a multi-beam inspection system may be 100 times greater than the throughput of a single beam inspection system.

[0040]

[0058] In known multi-beam systems, an array of primary sub-beams of relatively high energy charged particles is aimed at the target in a final deceleration step to land on the sample with a relatively low landing energy for detection of secondary signal particles as described above. However, in practice, it has generally not been possible to use multi-beam inspection in combination with backscattering detection, or at least with backscattering detection. That is, currently known multi-beam systems rely mainly on the detection of secondary signal particles. However, there is a limit to the information that can be obtained solely from secondary signal particles. Backscattering signal particles provide information about structures below the surface, for example buried defects. In addition, the backscattering signal can be used to measure overlay targets.

[0041]

[0059] As mentioned above, the backscattered signal particles typically have a large energy range between 0 eV and the landing energy. The backscattered signal particles have a large energy range (e.g., up to the landing energy of the primary beam) and a wide angle of the emitted backscattered signal particles. The secondary signal particles typically have a more limited energy range and tend to distribute around a certain energy value. The large energy range and wide angle of the emitted backscattered signal particles result in crosstalk in a multi-beam system. Crosstalk occurs when backscattered signal particles originating from one primary sub-beam are detected at detectors assigned to different sub-beams. Crosstalk generally occurs in close proximity to the sample 208, i.e., close to the sample where the primary beam is projected. Due to crosstalk, existing multi-beam evaluation tools have not been able to effectively image the backscattered signal. As a result, it has not been possible to increase the throughput for the detection of backscattering using a multi-beam system.

[0042]

[0060] Components of an evaluation tool 40 that can be used in the present invention are described below in connection with Figure 3, which is a schematic diagram of the evaluation tool 40. The charged particle evaluation tool 40 of Figure 3 can correspond to a multi-beam charged particle beam tool (also referred to herein as apparatus 40).

[0043]

[0061] The charged particle source 201 directs charged particles (e.g. electrons) towards an array of condenser lenses 231 (also called condenser lens array) which is part of the projection system 230. The charged particle source 201 is preferably a high brightness thermal field emitter with a good compromise between brightness and total emission current. There may be tens, hundreds or thousands of condenser lenses 231. The condenser lenses 231 may comprise multi-electrode lenses or may have a structure according to EP 1 602 121 A1, which is incorporated herein by reference in particular for its disclosure of a lens array for splitting an electron beam into a number of sub-beams, the array providing one lens per sub-beam. The array of condenser lenses 231 may take the form of at least two plates acting as electrodes, the apertures of each plate being aligned with each other and corresponding to the location of the sub-beams. At least two of the plates are maintained at different potentials during operation to achieve the desired lens effect.

[0044]

[0062] In one configuration, the array of condenser lenses 231 is formed by a three plate array, where the charged particles have the same energy when they enter and exit each lens, and this configuration may be called an Einzel lens. Thus, dispersion occurs only within the Einzel lens itself (between the entrance and exit electrodes of the lens), thereby limiting off-axis chromatic aberration. If the thickness of the condenser lens is small, for example a few mm, the effect of such aberrations is small or negligible. More generally, the condenser lens array 231 may have two or more plate electrodes, each of which has an array of aligned apertures. Each plate electrode array is mechanically connected to and electrically isolated from adjacent plate electrode arrays by isolation elements, such as spacers, which may include ceramic or glass. The condenser lens arrays may be connected to and / or spaced from adjacent charged particle optical elements, preferably electrostatically charged particle optical elements, by isolation elements, such as spacers, as described elsewhere herein.

[0045]

[0063] The collection lens may be separate from the module containing the objective lens (e.g., an objective lens array assembly described elsewhere herein). If the potential applied to the bottom surface of the collection 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 space the collection lens from the module containing the objective lens. If the potentials are equal, a conductive element can be used to space the collection lens from the module containing the objective lens.

[0046]

[0064] Each condenser lens 231 in the array directs the primary beam of charged particles into a respective sub-beam 211, 212, 213 that converges at a respective intermediate focus in the down beam of the condenser lens array. Each sub-beam is projected along a respective sub-beam path 220. The sub-beams diverge with respect to each other. The sub-beam paths 220 diverge in the down beam of the condenser lens 231. In one embodiment, a deflector 235 is provided at the intermediate focus. The deflector 235 is located in the sub-beam path at or at least around the position of the corresponding intermediate focus 233 or focus (i.e. the point of convergence). The deflector is located in or near the sub-beam path at an intermediate image plane of the associated sub-beam. The deflector 235 is configured to act on each sub-beam 211, 212, 213. The deflector 235 is configured to bend each sub-beam 211, 212, 213 by an amount effective to ensure that the chief ray (sometimes called the beam axis) is incident on the sample 208 substantially perpendicularly (i.e., at substantially 90° to the nominal surface of the sample). The deflector 235 may be called a collimator or a collimator-deflector. The deflector 235 effectively collimates the paths of the sub-beams. Thus, before the deflector, the sub-beam paths are diverging with respect to each other. At the deflector's down beam, the sub-beam paths are substantially parallel with respect to each other. That is, they are substantially collimated. A suitable collimator is the deflector disclosed in European Patent Application Publication No. 20156253.5, filed on February 7, 2020, which is incorporated herein by reference with respect to the application of deflectors to multi-beam arrays. The collimator may comprise a macro-collimator 270 instead of or in addition to the deflector 235. Thus, a macro-collimator 270, described below in relation to Figure 8, may be provided having the features of Figure 3 or Figure 4. This is generally less preferred than providing a collimator array as the deflector 235.

[0047]

[0065] Below the deflector 235 (i.e. down beam from the source 201 or away from the source 201) is the control lens array 250. The sub-beams 211, 212, 213 that have passed through the deflector 235 are substantially parallel when they enter the control lens array 250. The control lenses prefocus the sub-beams (e.g. apply a focusing action to the sub-beams before they reach the objective lens array 241). Prefocusing can reduce the divergence of the sub-beams or increase the convergence rate of the sub-beams. The control lens array 250 and the objective lens array 241 work together to provide a compound focal length. A compounding action without intermediate foci can reduce the risk of aberrations.

[0048]

[0066] In further detail, it is desirable to determine the landing energy using the control lens array 250. However, it is additionally possible to control the landing energy using the objective lens array 240. In such a case, when a different landing energy is selected, the potential difference across the objective lens is changed. An example of a situation in which it is desirable to partially change the landing energy by changing the potential difference across the objective lens is to prevent the focal point of the sub-beam from being too close to the objective lens. In such a situation, there is a risk that the components of the objective lens array 241 will become too thin to be manufactured. The same can be said for a detector at this location, for example, in, on or associated with the objective lens. This situation can arise, for example, when the landing energy is lowered. This is because the focal length of the objective lens is approximately proportional to the landing energy used. By lowering the potential difference across the objective lens and thereby lowering the electric field inside the objective lens, the focal length of the objective lens becomes larger again, so that the focal position is further below the objective lens. It should be noted that using only the objective lens provides limited control over the magnification. In such a configuration, it is not possible to control the demagnification and / or opening angle. Furthermore, using the objective lens to control the landing energy may mean that the objective lens will operate at a far from optimal field strength. This is the case unless the mechanical parameters of the objective lens (e.g., the spacing between the electrodes) can be adjusted, for example by replacing the objective lens.

[0049]

[0067] The control lens array 250 comprises a plurality of control lenses. Each control lens comprises at least two electrodes (e.g., two or three electrodes) connected to a respective potential source. The control lens array 250 may comprise two or more (e.g., three) plate electrode arrays connected to respective potential sources. The control lens array electrodes may be spaced a few millimeters (e.g., 3 mm) apart. The control lens array 250 is associated with the objective lens array 241 (e.g., the two arrays are placed 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 respective objective lens. The control lens array 250 is located in the up beam of the objective lens array 241. The up beam can be defined as being closer to the source 201. The up beam can alternatively be defined as being further from the sample 208. The objective lens array 241 may be in the same module as the control lens array 250, i.e. forming an objective lens array assembly or objective lens configuration, or the objective lens array 241 may be in a separate module. In this case, the configuration may be described as four or more lens electrodes, which are plates. The plates have apertures defined therein, e.g. as an aperture array, which are aligned to a number of sub-beams in a corresponding beam array. The electrodes may be grouped into two or more electrodes, e.g. providing a control electrode group and an objective electrode group. In one configuration, 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 separate, 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) may be selected from a wide range, e.g. from 2 mm to 200 mm, or even more. A small separation allows for easier alignment, while a large separation allows for the use of weaker lenses, reducing aberrations.

[0050]

[0068] Each plate electrode of the control lens array 250 is mechanically connected to and electrically isolated from adjacent plate electrode arrays by an isolation element, such as a spacer, which may comprise ceramic or glass. Each plate electrode of the objective lens array is mechanically connected to and electrically isolated from adjacent plate electrode arrays by an isolation element, such as a spacer, which may comprise ceramic or glass. Isolation elements, which may alternatively be referred to as insulating structures, may be provided to isolate adjacent electrodes in any of the objective lens array 240, the condenser lens array (as shown in FIG. 3), and / or the control lens array 250, etc. If more than one electrode is provided, multiple isolation elements (i.e., insulating structures) may be provided. For example, there may be a series of insulating structures.

[0051]

[0069] The control lens array 250 comprises a control lens for each sub-beam 211, 212, 213. The control lens adds an optical degree of freedom to the function of the associated objective lens. The control lens may comprise one or more electrodes or plates. Each additional electrode can provide an additional degree of freedom of control of the charged particle optical function of the associated objective lens. In one configuration, the function of the control lens array 250 is to optimize the beam opening angle for the beam demagnification and / or to control the beam energy provided to the objective lens 234, each of which directs the respective sub-beam 211, 212, 213 onto the sample 208. The objective lens may be located at or near the base of the charged particle optical system. More specifically, the objective lens array may be located at or near the base of the projection system 230. The control lens array 250 is optional, but is preferred to optimize the sub-beams in the up beam of the objective lens array.

[0052]

[0070] For ease of illustration, lens arrays are generally represented herein by an array of elliptical shapes (as shown in FIG. 3). Each elliptical shape represents one of the lenses in the lens array. An elliptical shape is conventionally used to represent a lens by analogy with the biconvex shape often adopted by optical lenses. However, it should be understood that in the context of charged particle configurations as discussed herein, lens arrays will typically operate electrostatically and may not require physical elements adopting a biconvex shape. Lens arrays may instead comprise a number of plates having apertures.

[0053]

[0071] Optionally, an array of scan deflectors 260 is provided between the control lens array 250 and the array of objective lenses 234. The array of scan deflectors 260 comprises a scan deflector for each sub-beam 211, 212, 213. Each scan deflector is configured to deflect a respective sub-beam 211, 212, 213 in one or two directions to scan the sub-beam across the sample 208 in one or two directions.

[0054]

[0072] The objective lens array 241 may comprise at least two electrodes, in which an aperture array is defined. In other words, the objective lens array comprises at least two electrodes with a plurality of holes or apertures. Adjacent electrodes of the objective lens array 241 are spaced apart from each other along the sub-beam paths. The distance between adjacent electrodes along the beam path, in which an insulating element may be placed as described below, is smaller than the size of the objective lens (along the beam path, i.e., between the most up-beam electrode and the most down-beam electrode of the objective lens array). Figure 4 shows electrodes 242, 243 that are part of an exemplary objective lens array 241 with respective aperture arrays 245, 246. The position of each aperture of the electrodes corresponds to the position of the corresponding aperture of another electrode. The corresponding apertures act on the same beam, sub-beam or sub-beam group in the multi-beam in use. In other words, corresponding apertures of at least two electrodes are aligned with and located along one sub-beam path, i.e. one of the sub-beam paths 220. Each electrode thus comprises an aperture through which the respective sub-beam 211, 212, 213 propagates.

[0055]

[0073] The aperture array 245, 246 of the objective lens array 241 may be composed of a plurality of apertures, preferably with a substantially uniform diameter. However, there may be some variations to optimize the aberration correction, as described in European Patent Application Publication No. 20207178.3, filed 12 November 2020, which is incorporated herein by reference, at least with respect to the correction realized by varying the diameter of the apertures. The diameter d of the aperture of at least one electrode may be less than about 400 μm. Preferably, the diameter d of the aperture of at least one electrode is about 30-300 μm. With a smaller aperture diameter, the detectors of the detector array 240 are larger for a given aperture pitch, which may improve the possibility of capturing backscattered signal particles. Thus, the signal for the backscattered signal particles may improve. However, if the aperture is too small, there is a risk of causing aberrations of the primary sub-beam. The apertures of the electrode may be spaced apart from one another by a pitch P. The pitch P is defined as the distance from the center of one aperture to the center of an adjacent aperture. The pitch between adjacent apertures of at least one electrode may be less than about 600 μm. Preferably, the pitch between adjacent apertures of at least one electrode is between about 50 μm and 500 μm. Preferably, the pitch between adjacent apertures on each electrode is substantially uniform. The above-mentioned diameter and / or pitch values ​​may be provided for at least one electrode, multiple electrodes, or all electrodes of the objective lens array. Preferably, the dimensions referenced and described apply to all electrodes provided in the objective lens array.

[0056]

[0074] The objective lens array 241 may comprise two or three electrodes, or may have more electrodes (not shown). An objective lens array 241 with only two electrodes may have less aberrations, e.g., lower risk and / or impact of aberrations, than an objective lens array 241 with more electrodes. A three-electrode objective lens may allow for a more powerful lens, since it has a larger potential difference between the electrodes. Additional electrodes (i.e., three or more electrodes) provide additional degrees of freedom to control the charged particle trajectory, e.g., to focus the secondary signal particles as well as the incident beam. The advantage of a two-electrode lens over an Einzel lens is that the energy of the incoming beam is not necessarily the same as the outgoing beam. Beneficially, the potential difference in such a two-electrode lens array allows the two-electrode lens array to function as either an acceleration lens array or a deceleration lens array. The objective lens array 241 may be configured to demagnify the charged particle beam by a factor of more than 10, preferably by a factor in the range of 50-100 or more. Each element of objective lens array 240 may be a microlens that acts on a different sub-beam or group of sub-beams of the multi-beam.

[0057]

[0075] Preferably, each electrode provided in the objective lens array 241 is a plate. The electrodes can alternatively be described as flat sheets. Preferably, each electrode is planar. In other words, each electrode will preferably be provided as a thin, flat plate with a planar shape. Of course, the electrodes do not have to be planar. For example, the electrodes may bend due to forces resulting from high electrostatic fields. Providing planar electrodes is preferred, since this makes the electrodes easier to manufacture, since known manufacturing methods can be used. Planar electrodes may also be preferred, since the alignment between the apertures of different electrodes may be more accurate.

[0058]

[0076] FIG. 5 is an enlarged schematic diagram of a plurality of objective lenses of the objective lens array 241 and a plurality of control lenses of the control lens array 250. As will be described in more detail below, the lens arrays may be provided with electrodes having selected potentials applied thereto by a voltage source. That is, the electrodes of the arrays are connected to respective potential sources. In FIG. 5, a plurality of lenses are shown in each of the control lens array 250, the objective lens array 241, and the detector array 240, with any of the sub-beams 211, 212, 213 passing through the lenses, for example, as shown. Although FIG. 5 shows five lenses, any suitable number may be provided, for example, there may be 100, 1000, or about 10,000 lenses in the plane of the lenses. Features that are the same as those described above are given the same reference numbers. For the sake of brevity, the description of these features provided above applies to the features shown in FIG. 5. The charged particle optical device may comprise one, some, or all of the components shown in FIG. 5. Note that this drawing is schematic and may not be to scale. For example, as a non-limiting list, the sub-beams may be narrower in the controller array 250 than in the objective lens array 241; the spacing between the detector array 240 and the electrodes of the objective lens array 241 may be closer than the spacing between the electrodes of the objective lens array 241 from each other; the focal point of each sub-beam between the controller lens array 250 may be closer to the objective lens array 241 than shown. As shown in FIG. 5, the spacing between the electrodes of the control lens array 250 may be greater than the spacing between the electrodes of the objective lens array 241, although this is not required.

[0059]

[0077] As shown in FIG. 5, the sub-beams may be parallel as shown in FIG. 3 when entering the control lens array 250. However, the same components of FIG. 5 may be used in the configuration shown in FIG. 8, in which case the sub-beams may be further separated (or generated) from the beam from the source of the down beam. For example, the sub-beams may be defined by a beam-limiting aperture array, which may be part of a lens configuration, e.g., the objective lens array, the control lens array, or any other lens element that may be associated with the objective lens array, e.g., that is part of the objective lens array assembly. As shown in FIG. 8, the sub-beams may be separated from the beam from the source by a beam-limiting aperture array, which may be part of the control lens array 250, as the most up beam electrode of the control lens array 250.

[0060]

[0078] Voltage sources V3 and V2 (which may be provided by individual power sources or all supplied by power source 290) are configured to apply potentials to the upper and lower electrodes of objective lens array 241, respectively. The upper and lower electrodes may be referred to as up beam electrodes 242 and down beam electrodes 243, respectively. Voltage sources V5, V6, V7 (which may be provided by individual power sources or all supplied by power source 290) are configured to apply potentials to the first, second and third electrodes of control lens array 250, respectively. A further voltage source V4 is connected to the sample and applies a sample potential. A further voltage source V8 is connected to the detector array and applies a detector array potential. Although control lens array 250 is shown having three electrodes, control lens array 250 may comprise two electrodes (or more than three electrodes). Although the objective lens array 240 is shown with two electrodes, the objective lens array 240 may comprise three electrodes (or four or more electrodes). For example, between the electrodes shown in FIG. 5, the objective lens array 241 may be provided with an intermediate electrode with a corresponding voltage source V1 (not shown). Desirably, the potential V5 of the uppermost electrode of the control lens array 250 is maintained the same as the potential of the next charged particle optical element (e.g., deflector 235) in the up beam of the control lens. The potential V7 applied to the lower electrode of the control lens array 250 can be varied to determine the beam energy. The potential V6 applied to the intermediate electrode of the control lens array 250 can be varied to determine the lens strength of the control lens and thus control the opening angle and reduction ratio of the beam. It should be noted that the control lens can be used to control the opening angle of the beam even if the landing energy does not need to be changed or is changed by other means. The positions of the focal points of the sub-beams are determined by a combination of the operation of each control lens array 250 and the operation of each objective lens 240 .

[0061]

[0079] The detector array 240 (alternatively, may be referred to as an array of detectors) comprises a number of detectors. Each detector is associated with a corresponding sub-beam (alternatively, may be referred to as a beam or a primary beam). In other words, the array of detectors (i.e., the detector array 240) and the sub-beams correspond to each other. Each detector may be assigned to one sub-beam. The array of detectors may correspond to the array of objective lenses. In other words, the array of detectors may be associated with a corresponding array of objective lenses. In the following, the detector array 240 is described. However, any reference to the detector array 240 may be replaced with a single detector (i.e., at least one detector) or multiple detectors, as appropriate. The detectors may alternatively be referred to as detector elements 405 (e.g., sensor elements such as capture electrodes). The detectors may be any suitable type of detector.

[0062]

[0080] The detector array 240 may be positioned at a position along the primary beam path anywhere between an upper beam position and a lower beam position along the beam path. The upper beam position is above the objective lens array and, optionally, any associated lens arrays, such as the control lens array (i.e., the up beam of the objective lens array assembly). The lower beam position is in the down beam of the objective lens array. In one configuration, the detector array may be an array in the up beam of the objective lens array assembly. The detector array may be associated with any electrode of the objective lens array assembly. Hereinafter, references to detectors associated with electrodes of the objective lens array may correspond to electrodes of the objective lens array assembly, except for the most down beam surface of the most down beam electrode of the objective lens array, unless explicitly stated otherwise.

[0063]

[0081] In one configuration, the detector array 240 may be disposed between the control lens array 250 and the sample 208. The detector array 240 may be disposed between the objective lens 234 and the sample 208, as shown in Figures 4 and 5. Although this may be preferred, the detector array 240 may be provided in additional or alternative locations, as shown in Figure 7. Multiple detector arrays may be provided in various locations, for example, as shown in Figure 7. Signal particles, including backscattered signal particles, may be detected directly from the surface of the sample 208. Thus, the backscattered signal particles may be detected without having to be converted into another type of signal particle, such as, for example, secondary signal particles, that may be easier to detect. Thus, the backscattered signal particles may be detected by the detector array 240 without encountering, e.g., colliding with, any other components or surfaces between the sample 208 and the detector array 241.

[0064]

[0082] The detector array is disposed between the objective lens array 241 and the sample 208. The detector array 240 is configured to be in close proximity to the sample. The detector array 240 may be in close proximity to the sample so as to detect backscattered signal particles from the sample 208. The detector is in close proximity to the sample, which allows for a reduction in the risk of crosstalk not being avoided in the detection of backscattered signal particles generated by sub-beams corresponding to other detectors of the detector array. In other words, the detector array 240 is very close to the sample 208. The detector array 240 may be within a certain distance from the sample 208, as described below. The detector array 240 may be adjacent to the sample 208. At least one detector may be disposed in the device so as to face the sample. That is, the detector may provide a base for the device. The detector as part of the base may face the surface of the sample. This may be beneficial in disposing the at least one detector in a location where the at least one detector is more likely to detect backscattered particles than secondary particles. For example, the at least one detector array may be provided at the output side of the objective lens array 241. The output side of the objective lens array 241 is the side where the sub-beams are output from the objective lens array 241, i.e. the bottom or down beam side of the objective lens array in the configurations shown in Figures 3, 4 and 5. In other words, the detector array 240 may be provided at the down beam of the objective lens array 241. The detector array may be located on the objective lens array or adjacent to the objective lens array. The detector array 241 may be an integrated component of the objective lens array 241. The detector and the objective lens may be part of the same structure. The detector may be connected to the lens by an isolation element or directly to the electrode of the objective lens. Thus, at least one detector may be part of an objective lens assembly comprising at least an objective lens array and a detector array. If the detector array is an integrated component of the objective lens array 241, the detector array 240 may be provided at the base of the objective lens array 241. In one configuration, the detector array 240 may be integrated into an electrode located in the most down beam of the objective lens array 241 .

[0065]

[0083] Ideally, the detector array is as close as possible to the sample. The detector array 240 is preferably very close to the sample 208, so that there is a close focus of the backscattered signal particles at the detector array. As mentioned above, the energy and angular spread of the backscattered signal particles is typically so large that it is difficult (or impossible in known prior art systems) to keep signals from adjacent sub-beams separated. However, the close focus means that the backscattered signal particles can be detected at the associated one of the detectors without crosstalk (i.e. interference from adjacent sub-beams) in the first aspect. Of course, there is a minimum distance between the sample 208 and the detector array 240. However, it is preferable to reduce this distance as much as possible. Certain configurations can benefit more from reducing this distance than others.

[0066]

[0084] Preferably, the distance "L" between the detector array 240 and the sample 208, as shown in FIG. 3, is about 50 μm or less. That is, the detector array 240 is located within about 50 μm of the sample 208. Although a small distance L (e.g., about 10-65 micrometers) is generally preferred because it can improve detector efficiency and / or reduce crosstalk, the distance may be larger. For example, the distance L may be about 100 micrometers or less, or about 200 micrometers or less. The distance L is determined as the distance between the surface of the sample 208 facing the detector array 240 and the surface of the detector array 241 facing the sample 208. A distance of about 50 μm or less is beneficial in that crosstalk between backscattered signal particles can be avoided or minimized. Theoretically, there may be a lower limit as to how close the sample 208 and the detector array 240 can be while still allowing these components to move relative to each other. This means that the distance L may be greater than about 5 μm or 10 μm. For example, a distance L of about 50 μm or less may be used while still allowing relatively reliable control of a device such as that shown in FIG. 3 as part of a tool. A distance L of about 30 μm or less may be preferred for other configurations, such as the configuration shown and described in connection with FIG. 8 below. A preferred range of the distance L between the detector array 240 and the sample 208 may be about 5 μm to 200 μm, or preferably about 5 μm to 100 μm, or preferably about 5 μm to 50 μm, or preferably about 10 μm to 50 μm, or preferably about 30 μm to 50 μm. In one configuration, for example, the detector array 240 is actuable relative to the objective lens array 241, i.e., the distance L can be changed, in order to substantially maintain the distance L between the sample and the detector array. Note that the distance L described here is for a multi-beam system such as that shown in FIG. 3 (or FIG. 8). The same distance may be used in a single beam device, such as that shown in FIG. 9, although for a single beam device, the distance L may be larger.

[0067]

[0085] The backscattered signal particles are emitted from the sample 208 with a very large energy spread, typically with an angular spread following a cosine distribution that may have the appearance of a cone in three dimensions. The greater the distance from the sample 208 to the detector array 240, the larger the cone of the emitted beam. It will be understood that the backscattered signal particles may have all angles. The cone of the emitted beam is a solid angle that can be assigned to the detector associated with each beam, and therefore this solid angle is larger the closer the sample and the detector are. Due to the very large energy spread, it may not be possible to image the backscattered signal particles coming onto the detector from different sub-beams without introducing significant crosstalk. The solution is to place the detector very close to the substrate and to select the pitch of the sub-beams such that the backscattered signal particle signals of adjacent sub-beams do not overlap.

[0068]

[0086] Thus, as mentioned above, the pitch size P can be selected depending on the distance between the detector array 240 and the sample 208 (or vice versa). By way of example only, if the distance L between the sample 208 and the detector array 240 is about 50 micrometers, the sub-beam pitch p may be about 300 micrometers or more. Such a combination may be particularly useful for detecting high energy signal particles, e.g. backscattered signal particles, with an acceleration lens. By way of example only, if the distance L between the sample 208 and the detector array 240 is about 10 micrometers, the sub-beam pitch p may be about 60 micrometers or more. Providing a closer detector array allows the use of a smaller sub-beam pitch p. This may be beneficial when using certain structures where the sub-beam pitch is beneficially smaller, e.g. the structure described in connection with and shown in FIG. 8 below. In a different exemplary configuration, the distance between the sample 208 and the detector array 240 is about 50 micrometers and the sub-beam pitch p is about 60 micrometers. Such different setups are intended for different operating settings and for detecting different types of signal particles. For example, such a combination may be particularly useful for detecting low energy signal particles, e.g., secondary signal particles, with a deceleration lens. The pitch p and distance L may be selected from the above values ​​such that the signals of high energy particles and low energy particles are large enough for simultaneous detection of high energy particles (e.g., backscattered signal particles) and low energy particles (e.g., secondary signal particles). It should be noted that there is no relevance or limitation on the distance L and pitch p for the function of the detector. However, due to the risk of crosstalk in adjacent detectors, it may be preferable to use a larger pitch p for a larger distance L. However, there may be other ways to reduce the risk of crosstalk, and any suitable combination of pitch p and distance L may be used.

[0069]

[0087] The detector array 240 (and optionally the objective lens array 241) may be configured to bounce back secondary signal particles emitted from the sample 208. This is beneficial as it reduces the number of secondary signal particles emitted from the sample 208 that travel back towards the detector array 240. The potential difference between the detector array 240 and the sample 208 can be selected to bounce back the signal particles emitted from the sample 208 away from the detector array 240. Preferably, the potential of the detector array may be the same as the potential of the down beam electrode of the objective lens array. The potential difference between the sample potential and the detector array potential is preferably relatively small, so that the primary sub-beams are projected through or through the detector array 240 onto the sample 208 without being significantly affected. In addition, the small potential difference has a negligible effect on the path of backscattered signal particles (which generally have larger energies up to the landing energy), meaning that the backscattered signal particles can still be detected while reducing or avoiding the detection of secondary signal particles. The potential difference between the sample potential and the detector array potential is preferably greater than a secondary signal particle threshold. The secondary signal particle threshold can determine the minimum initial energy of a secondary signal particle that can still reach the detector. Preferably, the secondary signal particle threshold is a potential difference equivalent to the expected energy of a secondary signal particle emanating from the sample 208. That is, a relatively small potential difference between the potentials of the sample and the detector array is sufficient to repel the secondary signal particles from the detector array. For example, the potential difference between the sample potential and the detector array potential can be about 20V, 50V, 100V, 150V, 200V, 250V, or 300V.

[0070]

[0088] The objective lens array 241 may be configured to accelerate the primary charged particles (i.e., sub-beams) along the sub-beam paths 220 towards the sample 208. Accelerating the sub-beams 211, 212, 213 projected onto the sample 208 is beneficial in that it can be used to generate an array of sub-beams with high landing energy. The potentials of the electrodes of the objective lens array can be selected to provide acceleration through the objective lens array 241. It should be noted that the acceleration lens in this configuration may be particularly useful for detecting a detection range (e.g., different energy range) of backscattered signal particles. Alternatively, the objective lens array may be configured to decelerate the primary charged particles along the sub-beam paths 220 towards the sample 208. It should be noted that the deceleration lens in this configuration may be particularly useful for detecting both secondary and backscattered signal particles. The figures described below, particularly Figures 3, 5 and 8, show the objective lens in acceleration mode. However, as will be appreciated from the above description, for any of the embodiments and variations described below, the objective lens may instead be used in deceleration mode. In other words, Figures 3, 5 and 8 can be adapted to decelerate the sub-beams through the objective lens.

[0071]

[0089] In one configuration of accelerating objective lens array 241, low energy particles (e.g., secondary signal particles) generally cannot pass through the up beam of the lower part of the acceleration objective lens. It is also more difficult for high energy particles (e.g., backscattered signal particles) to pass through the acceleration objective lens. This is an important point for both acceleration and deceleration objective lenses. The energy difference between low energy signal particles (e.g., secondary signal particles) and high energy signal particles (e.g., backscattered signal particles) is proportionally larger in the down beam of the objective lens (in both acceleration and deceleration modes) than at any point in the up beam of the objective lens. This is beneficial for detection using the detectors described below to distinguish different types of signal particles.

[0072]

[0090] The potentials and values ​​of potentials defined herein are defined relative to the source, and thus the potential of a charged particle at the surface of the sample may be referred to as the landing energy, since the energy of the charged particle correlates with the potential of the charged particle, and the potential of the charged particle at the sample is defined relative to the source. However, since the potential is a relative value, the potential can be defined relative to other components, such as the sample. In such cases, the difference in potentials applied to the different components is preferably similar to that described below with respect to the source. The potentials are applied to the electrodes and the relevant components, such as the sample, in use, i.e. during operation of the device.

[0073]

[0091] For example, a device configured to accelerate charged particle sub-beams and bounce secondary signal particles as described above may have potentials as shown in connection with FIG. 5, the values ​​of which are shown in Table 1 below. As described above, the objective lens array shown in FIG. 5 may include additional electrodes, e.g., intermediate electrodes. Such intermediate electrodes are optional and need not be included with the electrodes having other potentials listed in Table 1. The intermediate electrode of the objective lens array may have the same potential (e.g., V1) as the potential of the upper electrode of the objective lens array (i.e., V3).

[0074]

[0092] Exemplary ranges are shown in the left column of Table 1 above. The middle and right columns show more specific exemplary values ​​for V1-V8 within the exemplary ranges. The middle column can be provided for a smaller resolution than the right column. If the resolution is larger (as in the right column), the current per sub-beam may be larger and therefore the number of sub-beams may be smaller. The advantage of using a larger resolution is that less time is required to scan a "continuous area" (which may be a practical constraint). Thus, the overall throughput may be lower, but less time is required to scan the beam area (because the beam area is smaller).

[0075] [Table 1]

[0076]

[0093] For example, a device configured to decelerate the charged particle sub-beams and bounce the secondary signal particles as described above may have potentials as shown in connection with FIG. 5, the values ​​of which are shown in Table 2 below. To provide deceleration, the values ​​of the potentials provided to the acceleration lens may be swapped and adjusted. By way of example only, the charged particles may be decelerated from 30 kV to 2.5 kV at the objective lens. In one example, the potentials shown in FIG. 5, e.g., V2, V3, V4, V5, V6, and V7, may be set as shown in Table 2 below, to obtain landing energies in the range of 1.5 kV to 5 kV. V1 is optionally included when an intermediate objective lens electrode is included. The potentials and landing energies shown in Table 2 are merely examples, and other landing energies may be obtained, e.g., the landing energies may be less than 1.5 kV (e.g., about 0.3 kV or 0.5 kV) or may be greater than 5 kV. It can be seen that the beam energies at V1, V3, and V7 are the same. In an embodiment, the beam energy at these points may be between 10 keV and 50 keV. If lower potentials are selected, the electrode spacing may be reduced to limit the reduction in the electric field, especially at the objective lens. The potentials in this table are given as values ​​of beam energy in keV, which are equivalent to the electrode potential referenced to the cathode of the beam source 201. It will be appreciated that in designing a charged particle optical system, there is considerable design freedom as to which points in the system are set to ground potential, and that the operation of the system is determined by potential differences rather than absolute potentials.

[0077] [Table 2]

[0078]

[0094] To maximize detection efficiency, it is desirable to make the surface of the detector elements 405 as large as possible so that substantially all of the area of ​​the objective lens array 240 (excluding the apertures) is occupied by the detector elements 405. Additionally or alternatively, each detector element 405 has a diameter substantially equal to the array pitch (i.e., the pitch of the aperture array described above with respect to the electrodes of the objective lens assembly 241). In one embodiment, the outer shape of the detector elements 405 is circular, but it can be square or hexagonal to maximize the detection area.

[0079]

[0095] However, a larger surface of the detector element 405 leads to a larger parasitic capacitance and therefore a smaller bandwidth. For this reason, it may be desirable to limit the outer diameter of the detector element 405, especially if a larger detector element 405 leads to only a small increase in detection efficiency but a significant increase in capacitance. A circular (annular) detector element 405 may provide a good compromise between collection efficiency and parasitic capacitance. A larger outer diameter of the detector element 405 may also lead to a larger crosstalk (sensitivity to signals of adjacent holes). This may also be a reason to make the outer diameter of the detector element 405 smaller, especially if a larger detector element 405 leads to only a small increase in detection efficiency but a significant increase in crosstalk.

[0080]

[0096] In one embodiment, the objective lens array 241, by itself or in combination with other elements such as a control lens array and / or a detector array, is a replaceable module. The replaceable module may be field replaceable, i.e., the module can be swapped in with a new module by a field technician. In one embodiment, multiple replaceable modules are included within the tool and can be swapped between operative and inoperative positions without opening the tool.

[0081]

[0097] In some embodiments, one or more aberration correctors are provided to reduce one or more aberrations in the sub-beams. In any of the embodiments, one or more aberration correctors may be provided, for example, as part of the charged particle optical device, and / or as part of the optical lens array assembly, and / or as part of the evaluation tool. In one embodiment, at least a subset of the aberration correctors are each located at or directly adjacent to a corresponding one of the intermediate foci (e.g., in or adjacent to the intermediate image plane). The sub-beams have a minimum cross-sectional area at or near a focal plane, such as the intermediate plane. This provides more space for the aberration correctors than is available elsewhere, i.e., in the up or down beams of the intermediate plane (or than would be available in an alternative configuration that does not have an intermediate image plane).

[0082]

[0098] In one embodiment, an aberration corrector located at or adjacent to the intermediate focus (or intermediate image plane) comprises a deflector to correct for source 201 appearing to be in different positions relative to the different sub-beams. The corrector can be used to correct for macroscopic aberrations arising from the source that prevent good alignment between each sub-beam and the corresponding objective lens.

[0083]

[0099] The aberration correctors can correct aberrations that prevent proper column alignment. Such aberrations may also lead to misalignment between the sub-beams and the correctors. For this reason, it may be desirable to additionally or alternatively place the aberration correctors at or near the collecting lenses 231 (e.g., each such aberration corrector is integrated into or directly adjacent to one or more of the collecting lenses 231). This is desirable because at or near the collecting lenses 231, the aberrations have not yet caused a shift of the corresponding sub-beams, since the collecting lenses are vertically close to or coincident with the beam aperture. However, a challenge with placing the correctors at or near the collecting lenses is that each sub-beam has a relatively larger cross-sectional area and a relatively smaller pitch at this location than at a location further downstream (or down beam). The collecting lenses and the correctors may be part of the same structure. For example, they may be connected to each other, for example by an electrical isolation element. The aberration corrector may be a CMOS-based individual programmable deflector as disclosed in EP 2 702 595 A1, or an array of multipole deflectors as disclosed in EP 2 715 768 A2, the descriptions of sub-beam manipulators in both of these documents being incorporated herein by reference.

[0084]

[0100] In some embodiments, at least a subset of the aberration correctors are each integrated into or directly adjacent to one or more of the objective lenses 234. In one embodiment, the aberration correctors reduce one or more of field curvature, focus error, and astigmatism. The objective lenses and / or control lenses and correctors may be part of the same structure. For example, they may be connected to each other, for example, by electrical isolation elements. Additionally or alternatively, one or more scanning deflectors (not shown) may be integrated into or directly adjacent to one or more of the objective lenses 234 to scan the sub-beams 211, 212, 213 on the sample 208. In one embodiment, the scanning deflectors described in U.S. Patent Application Publication No. 2010 / 0276606 may be used, which is incorporated herein by reference in its entirety.

[0085]

[0101] 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. Thus, the detector comprises multiple portions, more specifically multiple detection portions. The different portions may be referred to as different zones. Thus, the detector may be described as having multiple zones or detection zones. Such a detector may be referred to as a zone detector. Signal particles captured by detector elements 405 surrounding one beam aperture 406 may be combined into a single signal or may be used to generate independent signals. Detectors with multiple portions may be provided in any of the detector arrays described herein.

[0086]

[0102] The zone detector may be associated with one of the sub-beams 211, 212, 213. Thus, multiple portions of one detector may be configured to detect signal particles emitted from the sample 208 in association with one of the sub-beams 211, 212, 213. A detector with multiple portions may be associated with one of the apertures in at least one of the electrodes of the objective lens assembly. More specifically, a detector 405 with multiple portions may be arranged around a single aperture 406 as shown in Figures 6A and 6B, which provide examples of such detectors.

[0087]

[0103] The zone detector portions may be separated in a variety of different configurations, for example radially, annularly, or in any other suitable configuration. Preferably, the portions are of similar angular size and / or similar area and / or similar shape, for example as shown in FIG. 6B. The separated portions may be provided as multiple portions, multiple annular portions (e.g. multiple concentric annuli or rings), and / or multiple sector portions (i.e. radial portions or sectors). The detector elements 405 may be radially divided. For example, at least one detector 405 may be provided as an annular portion comprising two, three, four or more portions. More specifically, as shown in FIG. 6A, the detector 405 may comprise an inner annular portion 405A surrounding the aperture 406 and an outer annular portion 405B radially outside the inner annular portion 405A. Alternatively, the detector elements 405 may be angularly divided. For example, the detector may be provided as a sector comprising two, three, four or more sections (e.g. eight, twelve, etc.). If the detector is provided as two sectors, each sector may be a semicircle. If the detector is provided as four sectors, each sector may be a quadrant. This is shown in FIG. 6B where 405 is divided into quadrants (i.e. four sectors). That is, four sectors are shown in FIG. 6B, as will be described below. Alternatively, the detector may comprise at least one segment portion. The electrode elements may be separated both radially and angularly, or in any other convenient manner.

[0088]

[0104] Each section may have a separate signal readout. A detector that is separated into sections, for example annular or sectoral sections, is beneficial in that it allows more information to be obtained about the detected signal particles. Thus, providing the detector 405 with multiple sections may be beneficial in obtaining additional information about the detected signal particles. This can be used to improve the signal-to-noise ratio of the detected signal particles. However, this incurs additional costs in terms of detector complexity.

[0089]

[0105] As shown in FIG. 6A, the detector, which defines an aperture 406 and is configured for the charged particle beam to pass through, comprises an inner detection portion 405A and an outer detection portion 405B. The inner detection portion 405A surrounds the detector aperture 406. The outer detection portion 405B is radially outside the inner detection portion 405A. The detector may be substantially circular in shape. Thus, the inner and outer detection portions may be concentric rings. In one example, the detector may be split into two (or more) concentric rings as shown in FIG. 6A.

[0090]

[0106] Providing multiple sections concentrically or otherwise is beneficial because different sections of the detector can be used to detect different signal particles, which may be, for example, smaller angle signal particles and / or larger angle signal particles, or secondary signal particles and / or backscattered signal particles. Such an arrangement of different signal particles may be suitable for a concentrically compartmentalized detector. Backscattered signal particles with different angles may be beneficial in providing different information. For example, for signal particles emitted from a deep hole, backscattered signal particles with small angles are more likely to come from the hole bottom, and backscattered signal particles with large angles are more likely to come from the hole surface and material surrounding the hole. In an alternative embodiment, backscattered signal particles with small angles are more likely to come from a deeper buried feature, and backscattered signal particles with large angles are more likely to come from material above the sample surface or buried feature.

[0091]

[0107] 8 is a schematic diagram of an exemplary charged particle optical system, e.g., an evaluation tool, having a charged particle device as in any of the above-mentioned options or aspects. The charged particle device is configured to project a beam of charged particles onto a sample. A charged particle optical device having at least an objective lens array 241 as described in any of the above-mentioned aspects or embodiments may be used in the charged particle optical system shown in FIG. 8. For the sake of brevity, features of the objective lens array 241 already described above may not be repeated here.

[0092]

[0108] There are some considerations specific to the setup of FIG. 8. In this embodiment, it is preferable to keep the pitch small to avoid adversely affecting throughput. However, if the pitch is too small, it can lead to crosstalk. The pitch size is therefore a balance between effective detection of selected signal particles, such as backscattered signal particles, and throughput. Thus, in such a configuration for detection of backscattered signal particles, the pitch is preferably about 300 μm, which is 4-5 times larger than the value in the embodiment of FIG. 8 when detecting secondary signal particles. As the distance between the detector and the sample 208 is reduced, the pitch size can also be reduced without adversely affecting crosstalk. Thus, having the detector as close as possible to the sample (i.e., making the distance L as small as possible, preferably about 50 μm or less, or about 40 μm or less, or about 30 μm or less, or about 20 μm or less, or equal to about 10 μm) is beneficial in allowing the pitch to be as large as possible, thereby improving throughput.

[0093]

[0109] As shown in FIG. 8, the charged particle optical system comprises a source 201. The source 201 provides a beam of charged particles (e.g. electrons). The multiple beams focused on the sample 208 originate from the beam provided by the source 201. The sub-beams 211, 212, 213 can be derived from the beam, for example, using a beam limiter (alternatively sometimes called a beam limiting aperture array) that defines an array of beam limiting apertures. The beam may be separated into the sub-beams 211, 212, 213 when it encounters the control lens array 250. The sub-beams 211, 212, 213 are substantially parallel when they enter the control lens array 250. (In one configuration, the control lens array 250 comprises a beam limiter.) The source 201 is preferably a high brightness thermal field emitter with a good compromise between brightness and total emission current. In the illustrated example, a collimator is provided in the up beam of the objective lens array assembly. The collimator may comprise a macro collimator 270. The macro collimator 270 acts on the beam from the source 201, which is then split into multiple beams. The macro collimator 270 collimates the beam from the source such that the beam cross section substantially matches the beam limiter upon incidence. The macro collimator 270 bends each portion of the beam from which sub-beams are extracted by an amount effective to ensure that the beam axis of each sub-beam [extracted from the beam] is incident substantially perpendicularly on the sample 208 (i.e., at substantially 90° to the nominal surface of the sample 208). The macro collimator 270 applies macroscopic collimation to the beam. Thus, rather than comprising an array of collimator elements configured such that each collimator element acts on a different individual portion of the beam, the macro collimator 270 may act on all of the beam. The macro collimator 270 may comprise a magnetic lens or a magnetic lens arrangement comprising multiple magnetic lens subunits (e.g., multiple electromagnets forming a multipole arrangement). Alternatively or additionally, the macro-collimator may be at least partially implemented electrostatically. The macro-collimator may comprise an electrostatic lens or an electrostatic lens arrangement comprising a number of electrostatic lens sub-units.The macro-collimator 270 may use a combination of magnetic and electrostatic lenses.

[0094]

[0110] In another configuration (not shown), the macro collimator may be partially or completely replaced by a collimator element array provided in the down beam of the upper beam limiter. Each collimator element collimates a respective sub-beam. The collimator element array may be formed using MEMS fabrication techniques to be spatially compact. The collimator element array may be the first deflection or focusing charged particle optical array element in the beam path of the down beam of the source 201. The collimator element array may be the up beam of the control lens array 250. The collimator element array may be in the same module as the control lens array 250.

[0095]

[0111] In the embodiment of FIG. 8, a macro scan deflector 265 is provided to scan the sub-beams across the sample 208. The macro scan deflector 265 deflects the respective portions of the beam to scan the sub-beams across the sample 208. In one embodiment, the macro scan deflector 265 comprises a macroscopic multipole deflector, for example having eight or more poles. The deflection is such that the sub-beams taken from the beam are scanned across the entire sample 208 in one direction (e.g. parallel to a single axis, such as the X axis) or in two directions (e.g. with respect to two non-parallel axes, such as the X axis and the Y axis). The macro scan deflector 265 acts on the entire beam, rather than comprising an array of deflector elements, each deflector element configured to act on a different individual portion of the beam. In the illustrated embodiment, the macro scan deflector 265 is provided between the macro collimator 270 and the control lens array 250.

[0096]

[0112] In another configuration (not shown), the macro scan deflector 265 may be partially or completely replaced by a scan deflector array. The scan deflector array 260 comprises a plurality of scan deflectors. The scan deflector array 260 may be formed using MEMS fabrication techniques. Each scan deflector scans a respective sub-beam on the sample 208. Thus, the scan deflector array 260 may comprise a scan deflector for each sub-beam. Each scan deflector may deflect the sub-beam unidirectionally (e.g., parallel to a single axis such as the X-axis) or bidirectionally (e.g., about two non-parallel axes such as the X-axis and the Y-axis). The deflection is such that the sub-beam is scanned unidirectionally or bidirectionally (i.e., one-dimensionally or two-dimensionally) across the sample 208. The scan deflector array may be the up beam of the objective lens array 241. The scan deflector array may be the down beam of the control lens array 250. Although reference is made to a single sub-beam associated with a scan deflector, a group of sub-beams may be associated with the scan deflector. In one embodiment, the scan deflector array may be implemented using the scan deflector described in EP 2425444, which is incorporated herein by reference in its entirety, particularly with respect to the scan deflector. A scan deflector array (e.g., formed using MEMS fabrication techniques as described above) may be more spatially compact than a macro scan deflector. The scan deflector array may be in the same module as the objective lens array 241.

[0097]

[0113] In other embodiments, both a macro scan deflector 265 and a scan deflector array are provided. In such configurations, scanning the sub-beams across the sample surface can be achieved by controlling the macro scan deflector and the scan deflector array 260 together, preferably in a synchronized manner.

[0098]

[0114] The invention is applicable to a variety of different tool architectures. For example, the charged particle beam tool 40 may be a single beam tool, or may comprise multiple single beam columns, or may comprise multiple columns (e.g. sub-beams) of a multi-beam. The columns may comprise a charged particle optical device as described in any of the embodiments or aspects above. As a multiple column (or multi-column tool), the devices may be arranged in an array that may have a number of columns ranging from 2 to 100. The charged particle device may take the form of an embodiment as described with respect to and shown in FIG. 3 or as described with respect to and shown in FIG. 8, but preferably comprises an electrostatic scanning deflector array and / or an electrostatic collimator array, for example in an objective lens array assembly. The charged particle optical device may be a charged particle optical column. The charged particle column may optionally comprise a source.

[0099]

[0115] As mentioned above, the array of detectors 240 may be provided between the objective lens array 241 and the sample 208, as shown in Figures 4 and 5. The array of detectors 240 may be associated with at least one electrode of the objective lens array, preferably the lower electrode 243. Preferably, the array of down beams of detectors 240 faces the sample 208 in use, i.e. when a sample is present.

[0100]

[0116] Additional or alternative detector arrays may be provided and these may be located elsewhere. This is shown in FIG. 7. One, some or all of the detector arrays may be provided as shown in FIG. 7. If multiple detector arrays are provided, they may be configured to detect signal particles simultaneously. The detector array 240, located between the objective lens array 241 and the sample 208, is shown as a segmented detector, as described in connection with FIGS. 6A and 6B. However, any suitable type of detector may be used for this array.

[0101]

[0117] The charged particle optical device may comprise an array of detectors, referred to herein as an array of mirror detectors 350. The array of mirror detectors 350 is arranged along the primary beam path 320 (e.g., at a common position along the primary beam path). The array of mirror detectors 350 is configured to face the up beam of the primary beam path 320. In other words, the array of mirror detectors 350 is configured to face along the primary beam path 320 toward the source of the primary beam (mentioned above as source 201). The array of mirror detectors 350 is configured to face in a direction away from the sample 208. The array of mirror detectors 350 may alternatively be referred to as an upper array of detectors. Preferably, the array of mirror detectors 350 is associated with the lower electrode 243, and preferably with the surface of the up beam of the electrode. This may be beneficial, because if the array of mirror detectors 350 is provided relatively close to the sample 208, for example directly on or on the lower electrode 343, the signal particles may be more likely to be detected. When an array of mirror detectors 350 is placed within the objective lens array 241 (i.e., between the electrodes of the objective lens array 241), the detector may be referred to as an in-lens detector. In one configuration of an objective lens array assembly having multiple lens electrodes, other electrodes may feature mirror electrodes, so long as another electrode is located in the up beam of the mirror electrode to reflect signal particles towards the mirror electrode.

[0102]

[0118] The charged particle optical device may comprise at least one up-beam array of detectors, facing towards the sample, i.e. facing in the direction of the sample 208. In other words, the up-beam array of detectors may face towards the sample 208 in a direction along the primary beam path 320. The charged particle optical device may comprise an upper array of detectors 370. The upper array of detectors 370 may be associated with a down-beam surface of the upper electrode 242 of the objective lens array 241. More generally, if more electrodes are provided in the objective lens array, the upper array of detectors 370 can be associated with a down-beam surface of any appropriate electrode. The upper array of detectors 370 may be located between the upper electrode 342 and the lower electrode 343, or between any other electrodes above the lowermost electrode of the objective lens array. As mentioned above, the upper array of detectors 370 is provided (with reference to the primary sub-beams 211 and 212) in the up-beam of at least one electrode, which is the lower electrode 243 in relation to FIG. 7. Additionally or alternatively, the charged particle optical device may comprise an above-lens array of detectors 380. In other words, the up-beam array of detectors may be above the objective lens array 241. The above-lens array of detectors 380 may be in the up-beam of all electrodes forming the objective lens array 241. The above-lens array of detectors 380 may be spaced apart from the electrodes 242 such that the above-lens detector array 380 is a plate or substrate with its own mechanical support separate from the objective lens array.

[0103]

[0119] Any of the detector arrays can be associated with (e.g., located within, on, adjacent to, connected to, or integrated with) at least one electrode of the objective lens array 241 (e.g., the upper electrode 242 or the lower electrode 243). For example, the detector array may be within or on at least one electrode of the objective lens array 241. For example, the detector array may be positioned adjacent to one of the electrodes. In other words, the detector array may be positioned in close proximity and adjacent to one of the electrodes. For example, the detector array may be connected (e.g., mechanically connected) to one of the electrodes. In other words, the detector array may be attached to one of the electrodes by, for example, adhesive, or welding, or some other attachment method. For example, the detector array may be integrated into one of the electrodes. In other words, the mirror detector array may be formed as part of one of the electrodes.

[0104]

[0120] Combinations of detector arrays may be provided. For example, a down beam array of detectors 240, and / or an array of mirror detectors 350, and / or an upper array of detectors 370, and / or an above lens array of detectors 380 may be provided. The device may include additional arrays of detectors, which may be provided in any combination of the down beam array of detectors 240, and / or the array of mirror detectors 350, and / or the upper array of detectors 370, and / or the above lens array of detectors 380. As will be apparent from the above combinations of arrays, there may be any suitable number of detector arrays. For example, there may be two, or three, or four, or five, or six or more arrays of detectors, located in any suitable location, as described above with respect to the up beam array of detectors and / or the down beam array of detectors. Whatever detector arrays are provided, they may be used simultaneously. The potential of any detector array (e.g. the mirror detector array 350, and / or the top detector array 370, and / or the lens above detector array 380, and / or the down beam detector array 360, and / or any additional detector arrays) may be selected relative to the sample 208 potential to control detection of signal particles, at least that detector array. An array of sub-beams (alternatively called the primary beam array) may correspond to any / all detector arrays provided. Thus, the array of sub-beams may correspond to the mirror detector 240 array, and / or the down beam detector array 360, and / or the top detector array 370, and / or the lens above detector array 380. Thus, any / all detector arrays may be aligned to the sub-beams.

[0105]

[0121] 9 is a schematic diagram of an exemplary single beam charged particle beam tool 40 according to one embodiment. As shown in FIG. 9, in one embodiment, the charged particle beam tool 40 includes a sample holder 207 supported by a motorized stage 209 for holding a sample 208 to be inspected. The charged particle beam tool 40 includes a charged particle source 201. The charged particle beam tool 40 further includes a gun aperture 122, a beam limiting aperture 125 (or beam limiter), a collection lens 126, a column aperture 135, an objective lens assembly 132, and a charged particle detector 144 (alternatively, may be referred to as an electron detector). The objective lens assembly 132 may be a modified swing objective retarding immersion lens (SORIL) in some embodiments, which includes a pole piece 132a, a control electrode 132b, a deflector 132c, and an excitation coil 132d. The control electrode 132b has an aperture formed therein for the passage of the charged particle beam. The control electrode 132b forms a surface facing the sample 208. The charged particle beam tool 40 shown in FIG. 9 is a single beam system, but in one embodiment, a multi-beam system is provided. Such a multi-beam system may have the same features as shown in FIG. 9, such as the objective lens assembly 132. Such a multi-beam system may additionally have a beam limiter array, for example in the down beam of the condenser lens, for generating sub-beams. Associated with the beam limiter array, for example in the down beam of the beam limiter array, may be a number of charged particle array elements, such as deflector arrays and lens arrays, for optimizing and adjusting the sub-beams and reducing aberrations of the sub-beams. Such a multi-beam system may have a secondary column for detecting signal charged particles. A Wien filter may be in the up beam of the objective lens assembly to direct the signal particles towards a detector in the secondary column.

[0106]

[0122] In the imaging process, the charged particle beam emanating from the source 201 may pass through the gun aperture 122, the beam limiting aperture 125, the collection lens 126, and be focused by the modified SORIL lens onto a probe spot, which may then impinge on the surface of the sample 208. The probe spot may be scanned across the surface of the sample 208 by the deflector 132c or by other deflectors in the SORIL lens. Signal particles emanating from the sample surface may be collected by the charged particle detector 144 to form an image of the area of ​​interest on the sample 208.

[0107]

[0123] The condenser and illumination optics of the charged particle beam tool 40 may include or be supplemented by electromagnetic quadrupole charged particle lenses. For example, as shown in FIG. 9, the charged particle beam tool 40 may include a first quadrupole lens 148 and a second quadrupole lens 158. In one embodiment, the quadrupole lenses are used to control the charged particle beam. For example, the first quadrupole lens 148 can be controlled to adjust the beam current, and the second quadrupole lens 158 can be controlled to adjust the beam spot size and beam shape.

[0108]

[0124] As mentioned above, a compartmentalized detector may have multiple detector portions (e.g., sensor elements) as part of the detector element 405 as described above in connection with Figures 6A and 6B. The multiple detector portions for each detector element (or sensor unit) are provided around an aperture. The multiple detector portions may together have a circular perimeter and / or diameter. The multiple detector portions may together have an area that extends between the aperture and the perimeter of the multiple detector portions. The multiple detector elements may be arranged in a rectangular array or in a hexagonal array. Signals generated from signal particles captured by detector portions surrounding an aperture may be combined into a single signal or used to generate independent signals. The surface of the detector element, and optionally its detector portions, may substantially fill the surface of the substrate supporting the detector element.

[0109]

[0125] As shown in FIG. 10A, the surface of the detector array or detector module facing the sample, or even adjacent to the sample in use, features an array of detector elements (or array of detectors). Each detector element is associated with an aperture. Each detector element is associated with an assigned surface area of ​​the substrate of the detector module. The substrate is layered, for example by having a CMOS structure, so that each layer in the substrate is preferably located in close proximity relative to the respective detector element. Commercially available CMOS structures have a typical range of layers, for example 3-10 layers, typically about 5 layers. (For example, for ease of explanation, two functional layers may be provided. These two layers of wiring and logic layers may represent the required number of layers, and each layer is not limited to wiring or logic, respectively). The number of layers is limited by commercial availability, and any number of layers is feasible. However, in practical terms, the substrate has a limited number of layers due to the limited space available for efficient design.

[0110]

[0126] Ideally, the circuit layers of the substrate, which may be wiring and / or logic layers, have a portion assigned to each detector element (or detector). The assigned portions of the different layers may be referred to as cells 550. The arrangement of portions in the substrate for a complete multi-beam configuration may be referred to as a cell array 552. The cells 550 may be the same shape as the surface area assigned to each detector element, for example, hexagonal, or any reasonable shape that can be tiled and all shapes and / or areas may be similar, such as rectangular shapes. Having rectangular or linear shapes is more easily used with a placing and routing design. Such designs are generally implemented with software suitable for defining the chip in orthogonal directions with a rectangular type architecture, rather than an architecture that requires acute or obtuse angles, such as in a hexagonal architecture. In FIG. 10A, the cells 550 are shown as hexagons and the cell array 552 is shown as hexagons with individual cells. However, ideally, each is similarly positioned relative to the detector elements. Wiring routes 554 may connect to each cell 550. Wiring route 554 may be routed between other cells of cell array 552. Note: References to wiring routes being between cells of the array are intended to mean that the wiring route avoids at least the beam aperture of the array, e.g., of an aperture defined through the cell array. In configurations of circuit architectures, cell sizes at least in circuit layers may be reduced to accommodate the wiring route, so that the wiring route is routed between cells. Additionally or alternatively, the wiring route passes through cells of the cell array, preferably toward the periphery of the cell, e.g., to reduce interference of the wiring route with other circuitry within the cell. Thus, references to wiring routes between cells encompass wiring routes between circuits of the cells, and wiring routes within the cells that are at least around the beam aperture, preferably toward the periphery of the cell and through the cell, as well as any intermediate variations.In all these configurations, for example in CMOS architectures, the wiring route may be in the same die as other circuits, which may define circuits in the same cell as part of the wiring route or circuits in the cell around which the wiring route is routed. Thus, the cells and wiring route may be part of a monolithic structure. The wiring route 554 may signally connect the cells. Thus, the wiring route signals the cells 550 to the cell array or even to a controller or data processor external to the substrate or detector module. The circuit layer may include a data path layer for communicating the sensor signals from the cells to outside the cell array.

[0111]

[0127] The controller or data processor may be in front of the circuitry in the substrate or detector module, preferably outside the cell array, for example as a control and I / O circuit (not shown). The control and I / O circuit may be in the same die as the cell array, or the control and I / O circuit may be monolithically integrated with the cell array, for example in the same CMOS chip. The control and I / O circuit allows efficient connection between data from all cells of the cell array 552. For example, consider a configuration of 2791 cells, each with an 8-bit digital output. Such a configuration would have 22328 (i.e., 8 bit output x 2791 cells) signals to electronics located outside the CMOS chip. A standard way to do this is to use a SERDES circuit (serializer / deserializer). Such a circuit converts a large number of low data rate signals into a smaller number of high data rate signals by time division multiplexing. It is therefore beneficial to have the control and I / O circuit monolithic with the cell array, or at least within the detector module, rather than external to it.

[0112]

[0128] In an embodiment, the control and I / O circuitry may feature general support functions such as circuitry for communicating with electronic circuitry external to the CMOS chip to allow for loading specific settings for control of amplification and offsets such as subtraction as described herein.

[0113]

[0129] The circuit layer of the cell 550 is connected to the detector elements of each cell. The circuit layer comprises circuitry with amplification and / or digitization functions, for example it may comprise an amplifier circuit. The cell 550 may comprise a transimpedance amplifier (TIA) 556 and an analog-to-digital converter (ADC) 558, as shown in FIG. 10B. This figure shows the cell 550 in a schematic manner with an associated detector element, such as a capture electrode, and a feedback resistor 562 connected to the transimpedance amplifier 556, and an analog-to-digital converter 558. A digital signal line 559 from the analog-to-digital converter 558 leaves the cell 550. It is noted that the detector elements are shown as detector elements 560, and the feedback resistor is shown associated with the detector area as a disk 562, rather than associated with the transimpedance amplifier 556. This schematic is to show each of the detector elements and feedback resistor as an area to show their relative size, the reason for which will become apparent with reference to FIG. 10C.

[0114]

[0130] The transimpedance amplifier may comprise a feedback resistor Rf 562. The size of the feedback resistor Rf must be optimized. The larger the value of this feedback resistor, the lower the input-referred current noise. Thus, the signal-to-noise ratio at the output of the transimpedance amplifier is improved. However, the larger the resistor Rf, the smaller the bandwidth. A finite bandwidth results in a finite rise and fall time of the signal, which results in additional image blurring. An optimized Rf results in a good balance between the noise level and the additional image blurring.

[0115]

[0131] To implement the design, the circuitry, i.e. the amplifier circuitry associated with each detector element, should reside within the layer of the associated cell 550 and fit within the limited available area of ​​some of each associated layer. For a sub-beam pitch of 70 micrometers, the available area per layer in the cell is typically only 4000 square micrometers. Depending on the sensed secondary and / or backscattered signal particles, e.g. as a current to be measured by the detector element, the optimal value of the feedback resistor Rf can reach 30-300 megaohms. If such resistors are implemented as poly resistors in a standard CMOS process, the size of such resistors will be much larger than the area available in the CMOS layer of the cell 550. For example, a 300 megaohm resistor consumes about 500,000 square micrometers. This is about 130 times larger than the total available area.

[0116]

[0132] Typically, for example in CMOS architectures, such large resistors are made in a single layer, for example of polysilicon. Usually, there is a single layer of polysilicon. In some circumstances, layers can be provided with materials capable of providing high resistor values, but at such high aspect ratios (e.g., extreme length relative to the width of the resistive structures in the layer), the reliability of the resistor remains. Even if the cell has multiple layers used for such resistors, there must be many more layers, which are easily available using, for example, CMOS technology. Additionally or alternatively, a meandering path through different layers does not mitigate the high aspect ratio, and the risk of resistance variation is only posed by the interconnects between the different layers. Such interconnects affect the variation of the resistor resistance as the corners turn, as described later in this specification.

[0117]

[0133] It should be noted that such dimensions are calculated assuming 180 nm node architecture and processing. If a smaller processing node is used instead, it is unlikely that a factor of one thousand will be achieved in reducing the dimensions of the resistor structures. Furthermore, using 180 node architecture is preferable over smaller nodes for processing reasons. For example, interconnects at the 180 nm node are simpler to process. Post-processing of the detector chip, for example when etching the beam aperture 504, uses aluminum interconnects. Such post-processing at sub-180 nm nodes typically uses processes that use copper interconnects. Thus, processing at 180 nm is simpler than sub-180 nm.

[0118]

[0134] Furthermore, if such resistors are to be fabricated, the reliability of the resistor's specifications, as well as the space available for the resistors at any node, may be an issue.

[0119]

[0135] In layered chip architectures, e.g., CMOS, components and features are defined as structures in layers. The specifications of the components depend on the material and physical properties of the layer, the dimensions of the layer, especially its thickness, and the dimensions of the structures formed in the layer. Resistors can take the form of long narrow paths, routes or wires. Given space constraints, the paths may be non-linear and may have turns along their paths. For such long components, the width of the paths in the layers may vary, e.g., due to manufacturing tolerances. Turns may cause larger variations than linear sections of paths, limiting the precision in fabricating resistors to obtain a particular resistance value. With many turns and long lengths, resistors with such topologies may be fabricated with low reliability, resulting in a large range of equivalent resistor resistance values ​​in different cells of a cell array.

[0120]

[0136] Such resistive structures have a large surface area. Additionally or alternatively, resistors with such large surface areas will have additional, undesirable capacitance. Such capacitance is called parasitic capacitance. Parasitic capacitance can undesirably introduce noise and blurring, and affects the balance between noise, blurring and bandwidth optimization, as discussed elsewhere herein.

[0121]

[0137] The material properties of the layers can be chemically modified, however such modifications are unlikely to achieve orders of magnitude of size improvement to fit the available space in the cell, and such modifications are unlikely to significantly alter the topography of the feedback resistor, and thus can be achieved with the required specifications and with the desired reliability.

[0122]

[0138] Such requirements in reliability and size would enable a resistor to achieve its desired performance in terms of bandwidth, signal-to-noise ratio, and stability. Unfortunately, these requirements cannot be met.

[0123]

[0139] Alternative amplifier circuits are proposed that do not require such large feedback resistors. Examples include a transimpedance amplifier with a pseudo resistor as a feedback element, and a direct analog-to-digital converter that eliminates the need for a transimpedance amplifier. Two examples of direct analog-to-digital converters are using a low duty cycle switching resistor (FIG. 11) and using a reference capacitor (FIG. 12). An optional configuration is to remove the analog-to-digital converter 558 from the cell 550, so that the analog-to-digital converter is external to the cell array 552 and has a circuit wire 570 connected to a transimpedance amplifier 556 in the cell 550 (FIG. 10C). The configuration shown in FIG. 10C may be applied to an amplifier circuit, for example, as shown in FIGS. 11 and 12. We will now address each option in turn. The exemplary amplifier circuits described are only some suitable types of amplifier circuits that can be used. There may be other amplifier circuits that achieve similar advantages as those described herein, and that use similar circuit architectures for each cell as those described herein.

[0124]

[0140] An alternative amplifier circuit is a direct analog-to-digital converter, for example using switched resistors or capacitors, which are connected directly to the output of the detector element 503, as shown in Figures 11 and 12. A suitable type of direct analog-to-digital converter is a charge-balanced direct current-to-digital converter. By using a direct analog-to-digital converter, it is avoided to use a transimpedance amplifier and to have a feedback resistor Rf or a special alternative. By removing the transimpedance amplifier, the most power-consuming component in the amplifier circuit is removed, and the main source of input noise is removed. A delta-sigma modulator provides the best realization of a charge-balanced direct current-to-digital converter. Two possible solutions are shown in Figures 11 and 12: using a low duty cycle switched resistor as a reference and using a switched capacitor as a reference. These circuits are exemplary, and other suitable circuits can exist.

[0125]

[0141] A suitable direct current to digital converter with low duty cycle switching resistors is shown in simplified form in Figure 11. The circuit comprises an integrator A, which is fed by the output from the detector element 503, and a reference resistor R dac The capacitor C int is the feedback loop of integrator A. The signal output from integrator A is processed by a comparator for the final step of converting the analog signal to a digital signal. The bit stream bs is fed from the output of the comparator to the control switch using a charge balancing loop, which supplies a reference current I dac The control switch design provides feedback for the sensor current I in and the reference current I dac This helps ensure that the integrator does not clip its output signal. The output bit stream bs is in This is a digitized version of the original.

[0126]

[0142] When using such a direct current-to-digital converter with a low duty cycle switching resistor, for example in a CMOS circuit implementation, the reference resistor R dac This reduces the size of the clock period T clock For a very small fraction t in the reference register R dac This is achieved by connecting the input of integrator A to the input of integrator A. This results in a small duty cycle, t / T clock , for example 1:1000. This short connection time reduces the current I in , i.e., the sensor current, is the reference current I required to balance the charge transferred in dac This low duty cycle is sufficient to transfer the charge at the feedback resistor R of a standard transimpedance amplifier. Providing a reference current to balance the sensor current in this manner helps ensure that the reference noise is small. fThis allows the same effect as that achieved by a large resistor, such as a 100 Ω resistor, etc. Thus, this solution applies a resistor of a smaller size than would otherwise be used, and uses a duty cycle to increase its effective size, further minimizing the effective size of the resistor, an effect related to the circuit layers within the cell required by this type of amplifier circuit.

[0127]

[0143] A suitable direct current-to-digital converter with a reference capacitor is shown in simplified form in FIG. 12. Unless otherwise stated, this circuit has exactly the same features as the current-to-digital converter with low duty cycle switched resistor as shown in FIG. 11. A capacitive digital-to-analog converter 567 arranged in a switched configuration provides the reference current. Such a switched capacitor digital-to-analog converter includes at least one capacitor, and may include a parallel capacitor network. Individual capacitors are connected or disconnected to a switch based on the input. As a capacitor-based circuit, the capacitive digital-to-analog converter 567 includes a reference capacitor C dac Instead of the reference resistor Rdac, the reference capacitor C dac Since a capacitor is used, the selection of a suitable size capacitor is essential to obtain a suitable reference current I dac and thus the clock signal f s No pulser powered by is required. By limiting the use of the clock to the integrator, the effect of clock jitter is minimized. The sensor current I in Reference current I dac The effect of is to quantize the sensor current signal. This is effectively a direct digital conversion.

[0128]

[0144] As shown in FIG. 10C, the cell 550 comprises a transimpedance amplifier 556 connected to the detector element 560. Associated with this amplifier circuit is an effective feedback resistor 568. The output of the transimpedance amplifier is connected to an analog-to-digital converter 558 (not shown) remote from the cell. A circuit wire 570 connects the transimpedance amplifier and the analog-to-digital converter. The circuit wire 570 transmits an analog signal. Considering that the cell array 552 is densely packed, the analog-to-digital converter is external to the cell array, e.g., on the same die as the cell array 552 and / or monolithically integrated in the cell array 552. In one embodiment, the analog-to-digital converter 558 is present in the substrate of the detector module. Alternatively, the analog-to-digital converter is remote from the substrate, e.g., it is part of a processor external to the substrate.

[0129]

[0145] The component difference between the cells shown in Figures 10B and 10C is that the cell in Figure 10C includes only a transimpedance amplifier and does not include analog-to-digital conversion, and the circuit wire 270 carries an analog signal rather than a digital signal carried by an analog-to-digital converter. By removing the analog-to-digital converter from the cell 550, there is more space available in the circuit layer of the cell 550 for a feedback resistor element. This relative difference can be recognized by the relative size of the feedback resistor area 562 in Figures 10B and 10C (note, however, that the relative dimensions do not necessarily apply to other features in these two figures). If the amplifier circuit uses an alternative transimpedance amplifier circuit, for example, if a transimpedance amplifier with a pseudo resistor is used as the feedback element, there is even more space in the circuit layer of the cell 550.

[0130]

[0146] While it may be easier to fit the transimpedance amplifier 556 with pseudo resistor feedback element and the analog to digital converter in the circuit layer of the cell, in one configuration it is more practical due to space constraints for the analog to digital converter 558 to be external to the cell array 552. This is despite the use of pseudo resistors in the feedback element of the transimpedance amplifier, which results in one to two orders of magnitude gain in area. One consideration for determining whether the analog to digital converter 558 is external to the cell array 552 is the sub-beam pitch of the multi-beam. For example, with a sub-beam pitch of 70 micrometers, typically only 4000 square micrometers per layer of cells are available for circuitry, including amplifier circuitry.

[0131]

[0147] Under such space constraints, the transimpedance amplifiers are located within the cells of each beam. The analog-to-digital converters are located outside the array of sub-beams, i.e., outside the cell array. In one embodiment, the analog-to-digital converters are on the same die as the cell array, e.g., monolithically with the cell array. Such analog-to-digital converters may be located with control and I / O circuitry, which may be on the detector module or may be monolithically with the cell array 552. Locating the analog-to-digital converters outside the cell array may result in an area gain of about 2x.

[0132]

[0148] Circuit wires 570 connect the transimpedance amplifiers in cells 550 to associated analog-to-digital converters 558. Circuit wires 570 transmit analog signals. Unlike digital signals, data paths transmitting analog signals are susceptible to interference. Signal interference can come from crosstalk with other circuit wires and from external electric fields, such as those generated by sub-beams of the multi-beam, as well as electric fields from nearby charged particle optical components, such as objective lens array 241.

[0133]

[0149] The circuit wires 570 are routed through the wiring route 554 as shown in FIG. 10A. The wiring route 554 is routed such that the area of ​​the cell and its layer is used for the amplifier circuitry present on the cell. Thus, the wiring route 554 uses only the portion of the circuit layer on which the wiring route is present, i.e., between adjacent cells 550 (e.g., at least around the beam apertures 504, 406 of adjacent cells 550, through adjacent cells 550 facing the periphery of the cell, or between the circuitry in the layer assigned to adjacent cells 550, or any of the configurations described). This routing avoids structural interference between the amplifier circuitry and the architecture of the wiring route 554. The circuit wires are routed along the wiring route in the cell array in an outward direction, e.g., radially outward. There may be more circuit wires 570 closer to the periphery of the cell array 552 than in the portion of the wiring route 554 away from the periphery. The wiring route may have multiple circuit wires 570, which are present between the cells of the array, as described above. Thus, some of the wiring routes 554 may have more than one circuit wire 570. However, placing the circuit wires in close proximity to one another creates a risk of crosstalk between the circuit wires and interference with the analog signals transmitted by the circuit wires 570.

[0134]

[0150] The risk of crosstalk and signal interference can be at least reduced or even prevented by shielding the circuit wires 570 from each other within the wiring route. FIG. 13 shows a cross section of an exemplary configuration of a wiring route 554. Within the wiring route 554, there are one or more circuit wires 470 shown to run in the same direction as the wiring route 554, and a shielding configuration. The circuit wires are shown in the same layer. Above the circuit wire 570 there is an upper shielding layer 572, and below the circuit wire 570 there is a lower shielding layer 574. The upper and lower shielding layers of the shielding configuration are above and below the wiring route 554 and shield the circuit wire 570 from external electric fields of the wiring route 554. The shielding configuration has a shielding element in the same layer as the circuit wire 570. The shielding element may be an outer element 576 at the outer edge of the layer that includes the circuit wire 570. The outer element 576 shields the circuit wire 570 from external electric fields of the wiring route 554. The shielding elements may include an intermediate shielding element 578 that resides in a layer between adjacent circuit wires. Thus, the intermediate shielding element 578 may at least reduce, if not prevent, crosstalk between the circuit wires 570. In operation, a common potential is applied to the shielding layers 572, 574 and the shielding elements 576, 578. The potential may be a reference potential, such as ground potential.

[0135]

[0151] Although FIG. 13 shows a three-layer configuration, any number of layers may be used in the wiring route 570 as desired. For example, there may be two layers of circuit wires requiring three shielding layers, including an upper shielding layer 572, a lower shielding layer 574, and a middle shielding layer. The middle shielding layer may further reduce, if not prevent, crosstalk between circuit wires in different layers of the wiring route 570. Thus, there are five layers in total. For each additional layer of circuit wire, an additional middle shielding layer is required. Increasing the number of layers in the wiring route 554 reduces the percentage of layers required for wire routing, but such design variations require additional layers. Considering the limited number of layers, there is an optimal number of layers at which the width of the wiring route is reduced without exceeding the number of layers required elsewhere on the detector module substrate, which may be limited to five layers.

[0136]

[0152] A further consideration in the design of the wiring routes is the number of circuit wires that may need to be present in an exemplary design of a detector module, for example, consider the configuration of FIG. 13 with all circuit wires 570 in one layer.

[0137]

[0153] For example, the array of sub-beams is arranged in a hexagonal array with 30 rings. The detector module therefore has a cell array of corresponding design. The number of cells is about 3000, for example 2791. Suppose such a cell array has a pitch of 70 micrometers, the innermost cell is the 0th order ring (ring #0) and has a single cell, the innermost ring (ring #1) is around the central cell, and the outermost ring (ring N) defines the periphery of the cell array and consists of 6N cells. For a cell array of 30 rings, the total number of cells is equal to:

number

[0138]

[0154] The outermost ring has the highest number of signals that need to be routed through it. If we consider that the wiring routes are routed between each cell, these signals are routed through the outermost ring and between the cells of the outermost ring. Since the outermost ring consists of 180 cells (for example, multiply the 30th ring by 6, i.e., 30 x 6 = 6N), the number of signals that are carried through the outermost ring, for example, between the cells of the outermost ring, is:

number

[0139]

[0155] The maximum number of signals to be routed between adjacent cells through the outer ring is the total number of signals (2611) divided by the number of cells in the outermost ring (180), which is 15 (rounded up to 1 decimal place). For example, the wiring route has a shielding configuration so that the signals are sufficiently shielded to limit the effects of crosstalk and external electric fields. In a single layer wire circuit, the layer may have outer elements 576 at the edges of the wiring route and intermediate shielding elements 578 between adjacent circuit wires 570. For a wiring route of 15 circuit wires 570, there are 16 shielding elements, including 14 intermediate shielding elements and 2 outer shielding elements 576. Thus, between adjacent cells 550 in the outer ring in this example, a wiring route with all circuit wires in the same layer has 31 elements of interleaved shielding elements and circuit wires.

[0140]

[0156] For a cell array 552 for a beam array having a pitch of 70 micrometers, there is sufficient space or area available in the circuit layer for such a wiring route 554. In structures made using 180 nm node processes, the minimum half pitch of a metal layer is typically about 280 nm. In this context, a half pitch is a line and a pitch is an associated gap with a line and an adjacent gap. The associated gap is typically the same width as the line. A wiring route for 31 elements requires 31 pitches. However, the associated gap of one of the elements corresponding to the outer element 576 is not part of the wiring route 554 and separates the wiring route from the adjacent circuit. Thus, for 31 elements, 61 half pitches are required, which corresponds to a width of the circuit wiring 554 of 17.1 micrometers.

[0141]

[0157] In a different configuration, the beam array may be hexagonal with 108 rings and about 35000 cells, which may be considered a monolithic beam array. The outermost ring has about 650 cells. About 34350 signals need to be routed through the outermost ring. Therefore, about 54 signals need to be routed through adjacent cells in the outermost ring. A wiring route 554 with 54 circuit wires 570 has 55 shielding elements. Applying similar calculations as for the previous example in applying this architecture to a half pitch of 280 nm, the width of the circuit wires is less than 61 micrometers. This size fits between the cells 550 of the outermost ring. In an alternative configuration, the beam configuration is distributed into two or more strips, with one or more intermediate strips for routing support structures, cooling features such as conduits, data transmission lines, etc. Such a beam array may be referred to as a strip beam array. Thus, wiring routes may be routed through one or more intermediate strips. This allows for larger beam arrays, and therefore cell arrays, while still maintaining a reasonable size wiring route. If a strip beam array had the same number of sub-beams as a monolithic beam array, the wiring route would have fewer circuit wires 570 than a monolithic cell array, i.e., 54 fewer circuit wires 570. In fact, a strip beam array can achieve a larger number of sub-beams than a monolithic beam array due to the larger size of the beam array, which is limited by the maximum number of circuit wires that can be present in a wiring route.

[0142]

[0158] For example, optimization of noise performance in terms of bandwidth and noise optimization, as well as blur and noise balance, can be made possible by ensuring that the gain of the transimpedance amplifier is programmable. In such a configuration, the amplifier circuit of the cell, at least the transimpedance amplifier, is programmable. Such a programmable amplifier circuit can comprise, for example, a variable amplifier and / or a variable analog-to-digital converter in terms of its sensitivity. The variable amplifier has a variable amplification range that depends on the detected beam current detected by the detector element 503. For example, in the case of a low detected beam current or a sample with a smaller than typical secondary emission coefficient, the variable amplifier can be adjusted to provide a larger amplification than normally used. In the case of a higher than normal beam current detected by the detector element 503 or a sample with a larger than typical secondary emission coefficient, the variable amplifier can be adjusted to provide a smaller amplification.

[0143]

[0159] This functionality is beneficial for a transimpedance amplifier with a feedback element having a pseudo resistor. The pseudo resistor, unlike an ideal resistor with a single resistance at all applied potential differences, has different effective resistances upon application of different applied voltages. When providing different resistances, the transimpedance amplifier associated with the pseudo resistor operates as a variable amplification. When providing the amplifier with variable functionality, an optimized balance between noise level and image blur (herein above referred to as "additive blur") can be achieved. Beneficially, the programmable amplification circuit can match the output of the transimpedance amplifier to the input of the analog-to-digital converter. This can be as a programmable offset subtracted between the output of the transimpedance amplifier and the input of the analog-to-digital converter. The programmable offset may help to reduce the required number of bits that need to be transmitted from the amplification circuit of the cell. The programmable offset may be implemented in the programmable amplifier. These measures help to ensure that the dynamic range of the transimpedance amplifier and the analog-to-digital converter, and thus preferably the amplification circuit, is optimally used for different use cases. Such different use cases may include material properties of the sample under inspection, for example different evaluation tool configurations using different beam currents. The coverage can be enabled by providing a variable amplifier, and a variable offset or threshold (e.g., subtraction with a programmable offset) desirably allowing adjustment of the gain, threshold and bandwidth. As described elsewhere herein, circuitry associated with variable amplification and subtraction may be included in the control and I / O circuitry.

[0144]

[0160] To obtain more varying information about the sample, it is beneficial to detect different types of signal particles. For example, to measure an overlay target, secondary signal particles can be used to obtain data about the top grating (which may be present in the resist) and backscattered signal particles can be used to obtain data about the buried grating.

[0145]

[0161] In some systems, a detector may be provided that is used in different modes, for example switching between secondary signal particle detection and backscattered signal particle detection. To switch from secondary signal particle detection to backscattered signal particle detection, the electrostatic field between the sample and the detector is reversed and / or the landing energy is changed. The different charging conditions of the sample after changing the landing energy and / or the sample field may cause overlay measurement errors, because the different charging conditions may change the primary beam position. During switching, there is a risk that the system will fluctuate (sample position and / or beam position), resulting in overlay measurement errors. Therefore, an improvement can be implemented in the system to switch the detection mode between backscattered detection and secondary detection. Such a system is disclosed in EP20216927.2, at least the devices and methods for switching between different modes are incorporated herein by reference.

[0146]

[0162] In an alternative system, the detector is provided with a double ring detector pad. The use of a double ring charged base bottom detector can lead to a significant amount of cross signal in the rings. That is, detection of secondary signal particles in the outer ring is proposed to detect backscattered signal particles, and detection of backscattered signal particles in the inner ring is proposed to detect secondary signal particles. Such a system is disclosed in EP 21174518.7, whose devices and methods relating to double ring detector pads are incorporated herein by reference.

[0147]

[0163] In implementations of the present invention, the detection of the two types of detectors is sought to be improved, for example, by using more, if not all, of the available detection efficiency. Separation of secondary and backscattered signal particles can be achieved by using the large energy difference between the secondary and backscattered signal particles, as described above. In the present invention, both secondary and backscattered signal particles can be detected simultaneously, increasing collection efficiency compared to various known detectors.

[0148]

[0164] In the present invention, a detector is provided that can be used in a charged particle device for an evaluation tool to detect signal particles from a sample. For example, the charged particle device is configured to project a beam of charged particles onto the sample to detect signal particles emitted from the sample. An exemplary version of a detector 600 is shown in FIG. 14. The detector 600 comprises a substrate, which may alternatively be referred to as a body. The substrate comprises a semiconductor element 610 (e.g., a pin detector) configured to detect signal particles above a first energy threshold and a charge-based element 620 configured to detect signal particles below a second energy threshold. The resulting signal particles from the sample may include signal particles above the first energy threshold and / or signal particles below the second energy threshold. Thus, the detector 600 comprises two different types of detector elements, for example a first element and a second element. As can be seen from FIG. 14, the detector 600 may be used with a single beam device. Thus, for example, the detector may be used with a single beam device as described in connection with FIG. 9 above.

[0149]

[0165] Each of the different types of detector elements may be configured to primarily detect certain signal particles, e.g., signal particles above or below a certain threshold. Signal particles having an energy below a first energy threshold are indicated by dashed arrows in FIG. 14, and signal particles having an energy above a second energy threshold are indicated by solid arrows in FIG. 14. The first energy threshold may correspond to a backscatter threshold energy. Thus, the semiconductor element 610 (e.g., the first element) may be configured to primarily detect backscattered signal particles. The backscatter threshold energy may be a selected lowest energy level of backscattered signal particles that the detector is designed to detect. For example, the backscatter threshold energy may be about 50ev. The second energy threshold may correspond to a secondary threshold energy. Thus, the charged base element 620 (e.g., the second element) may be configured to primarily detect secondary signal particles. The secondary threshold energy may be a selected highest energy level of secondary signal particles that the detector is designed to detect. For example, the secondary threshold energy may be about 50ev. In one configuration, the first element is configured to detect backscattered signal particles and the second element is configured to detect secondary signal particles.

[0150]

[0166] The first and second energy thresholds may be substantially the same. Thus, the first and second energy thresholds may be a single, pre-determined value. In this case, the charge-based element 620 may be used to detect any signal particles below the pre-determined value, and the semiconductor element 610 may be used to detect any signal particles above the pre-determined value.

[0151]

[0167] 14, the detector 600 may have an aperture 601 defined in the substrate, through which the primary beam 320 can pass to land on the sample 208. This is beneficial in that the detection elements of the detector 600 can surround the aperture 601, increasing the detection efficiency.

[0152]

[0168] The charge-based element 620 may include a metal layer 621. The metal layer 621 may be a flat portion. The metal layer 621 may be a thin film. The charge-based element may have a thickness of about 100 nm or less, preferably about 10 nm to 100 nm. More specifically, the thickness of the metal layer 621 may be about 100 nm or less, preferably about 10 nm to 100 nm. Lower energy signal particles, having an energy of less than 50 eV (which may correspond to the secondary signal particles described above), may be "captured" by the charge-based element having a relatively small thickness. Higher energy signal particles have a larger penetration depth. For example, a signal particle having an energy of about 350 eV may have a penetration depth greater than 10 nm to 100 nm. This means that the lower energy signal particles may be captured by the charge-based element 620, and the majority of the higher energy signal particles pass through the charge-based element 620. The higher energy signal particles may be detected by the semiconductor element 610. Such a thickness is therefore beneficial in allowing the signal particles to effectively reach the semiconductor element 610. Collection efficiency can be improved by applying a bias between the sample 208 and the detector 600 to attract the signal particles to the detector, as described below.

[0153]

[0169] The semiconductor element 610 may be a PIN detector. Scintillators and PIN detectors are typically capable of detecting charged particles above a detection threshold, typically above about 1 kV, although lower values, for example 200 eV for PIN detectors, are known. For scintillators, the detection threshold can be varied by the choice of the thickness of a conductive coating, for example a metal layer, on the scintillator surface. The semiconductor element comprises an upper metal layer 612 and a lower metal layer 613 on either side of the pin region 611. The upper metal layer 612 may be a flat portion. The upper metal layer 612 may be a thin film. The lower metal layer 613 may be a flat portion. The lower metal layer 613 may be a thin film. The pin region 611 may alternatively be referred to as a depletion layer or depletion zone. The pin region 611 may comprise a dead layer at the edge of the pin region. The dead layer is an inactive section or area of ​​the entrance surface of the pin region. The dead layer may comprise a conductive layer, a surface passivation layer, and / or an anti-reflective coating. It is possible to have pin regions without dead layers, but dead layers are beneficial in reducing noise. Although pin regions are described throughout, other semiconductor regions may be used in place of the pin regions. For example, the semiconductor elements may comprise diffused junction diodes, surface barrier detectors (e.g., Schottky diodes), or ion implanted diodes.

[0154]

[0170] Preferably, each of the charge base element 620 and the semiconductor element 610 is at least part of a layer that is substantially coplanar with a major surface (i.e., a detection surface) of the detector. The detection surface is a surface of the detector for passage of signal particles to the semiconductor element 610 and / or the charge base element 620. It will be understood that layers of detector elements such as the charge base element 620 and the semiconductor element 610 are different parts of a layered detector structure.

[0155]

[0171] In one embodiment, the detector elements may be provided as layers or portions of a stack in the detector 600 that are stacked in the thickness direction of the detector. The stacked layers of the charge base elements 620 and the semiconductor elements 610 are shown in Figure 14. The layers of the charge base elements 620 and the semiconductor elements 610 are stacked in the direction of the primary beam 320.

[0156]

[0172] Preferably, the charge-based element is closer to the detector surface than the semiconductor element. Specifically, the metal layer 621 of the charge-based element 620 is preferably closer to the detector surface than the semiconductor element, or the metal layer 621 may form the detector surface. In general, higher energy signal particles can be detected by the semiconductor element 610 through the charge-based element 610 when they strike the detector surface.

[0157]

[0173] Providing detector elements stacked on top of each other is beneficial because the detector elements can fully utilize the available detection efficiency by using all the detection area available to the detector 600. In general, it is important to separate secondary signal particles (i.e., low energy signal particles) and backscattered signal particles (i.e., high energy signal particles). This is because typically more secondary signal particles than backscattered signal particles are generated in the sample, so that the secondary signal particles will dominate the signal if the signal particles are not sufficiently separated. The stacked detector can separate the signal particles based on the difference in energy and the difference in penetration depth. Specifically, the low energy signal particles corresponding to the secondary signal particles are captured by the charge base element 620. However, the high energy signal particles penetrate the charge base element 620 and generate electron-hole pairs in the depletion layer of the semiconductor element 610. Thus, the higher energy signal particles can be detected in the semiconductor element 610 below the charge base element 620. Thus, the stacked detector allows separate detection of the lower energy signal particles in the charge base element 620. The stacked detectors simultaneously allow for detection of higher energy signal particles at the semiconductor element 610. These improvements in functionality are beneficial for improving detection efficiency.

[0158]

[0174] The charge-based element 620 may form a detection surface of the detector. In other words, the charge-based element 620 may be the outermost layer of the detector 600, as shown in Figure 14. The metal layer 621 may form the detection surface. As shown in Figure 14, the metal layer 621 may form substantially the entire detection surface.

[0159]

[0175] As shown in Figure 14, the charge base element 620 may form a layer (e.g., a coating) over substantially the entirety of the semiconductor element 610. This means that the charge base element 610 is provided over the entire surface of the semiconductor element 620. In this case, the charge base element 610 may form substantially the entirety of the detection surface. In particular, as shown in Figure 14, the metallic surface layer 621 of the charge base element 620 may form substantially the entirety of the detection surface.

[0160]

[0176] The semiconductor element 610 and the charge base element 620 may be separated from each other. In particular, the detector may comprise an electrical insulation element 630 between the charge base element 620 and the semiconductor element 610. The electrical insulation element 630 may be provided as a layer. The electrical insulation element 630 may be a flat portion. The electrical insulation element may be a thin film. The electrical insulation element 630 may be provided in any shape or form. The electrical insulation element 630 is configured to prevent electrical signals from passing from the charge base element 620 to the semiconductor element 610 and vice versa. The electrical insulation element 630 may extend between the charge base element 620 and the semiconductor element 610. The electrical insulation element 630 may have any suitable thickness to provide effective electrical insulation. Preferably, the electrical insulation element 630 is not too thick to avoid that high energy charged particles cannot penetrate it and reach the active detector layer 611.

[0161]

[0177] The electrical insulating element 630 may have any suitable thickness between other components, for example between the metal layer 621 and the lower metal layer 613 (i.e. in the thickness direction of the detector, for example in the direction of the primary beam). For example, the thickness may be about 10-500 nm, preferably about 50-500 nm. It is noted that the electrical insulating element 630 is preferably thick enough to prevent a voltage breakdown depending on the voltage difference between the metal layer 621 and the lower metal layer 613 as in FIG. 14. If the same voltage is used on the lower metal layer 613 and the metal layer 621 (this is possible because only the voltage difference between the upper metal layer 612 and the lower metal layer 613 is important for the PIN detector to function), a thickness of 10 nm can be used, otherwise a thickness of 100 nm or more is preferably used. The thickness may depend on the material. The electrical insulating element may be any suitable material. For example, the electrical insulating element may be SiO2. In this case, the thickness of the electrically insulating element may preferably be between 10 nm and 500 nm, preferably about 100 nm.

[0162]

[0178] The detector may include a circuit layer 640 that includes detector circuitry. More specifically, the substrate may include the circuit layer 640. The circuit layer 640 may include some, if not all, of the circuitry used to process signals from the different detector elements. Thus, the circuit layer 640 may convert detected signal particles into electrical signals. The circuit layer 640 may include a variety of different electrical components. The circuit layer may be connected to the charge base elements 620 and the semiconductor elements 610 as described below. The circuit layer may include parallel layers of circuitry for connecting to each of the charge base elements 620 and the semiconductor elements 610. Alternatively, the circuit layer may include a single layer with cross-sectionally adjacent circuitry for connecting to each of the charge base elements 620 and the semiconductor elements 610.

[0163]

[0179] Providing the circuit layer 640 within the detector is beneficial in that it allows the circuitry to be close to the detector elements. The detector elements are connected to the circuitry to convert the detected signal to a digital signal. In general, having the circuitry for converting the detected signal to a digital signal as close as possible to the associated detector elements beneficially improves the digital detected signal. Proximity of the digitizing circuitry reduces the risk of loss of the detected signal, or at least degradation of the detected signal, or corruption of the detected signal.

[0164]

[0180] The detector 600 may further comprise an electrically insulating via 622 configured to connect the charge based element 620, in particular the metal layer 621, to a detector circuit. That is, the electrically insulating via 622 is for the detector to detect signal particles via a connection to the charge based element. As shown in FIG. 14, the electrically insulating via 622 may extend through at least a portion of the semiconductor element 610. Thus, the charge based element 620 may be connected to the circuit layer 640 by an electrical connection along the electrically insulating via 622. This means that the charge based element 620 may be used to form a detection surface or at least a portion of a detection surface and still be appropriately connected to the circuit of the detector.

[0165]

[0181] The upper metal layer 612 of the semiconductor element 610 is preferably connected to a detector circuit (preferably provided in a circuit layer 640). In addition, the lower metal layer 613 may be connected to the detector circuit. The detector circuit may be configured to apply a voltage bias 641 across the upper and lower metal layers of the semiconductor element 610.

[0166]

[0182] As described in more detail below, the circuit layer 640 may comprise or be connected to circuit layers and / or wiring, as described above in connection with Figures 10, 11, 12 and 13. For example, the detector circuit may comprise a transimpedance amplifier 556 and / or an analog-to-digital converter 558 connected to the charge-based element 620. The detector circuit may comprise a transimpedance amplifier 556 and / or an analog-to-digital converter 558 connected to the semiconductor element 620. Such transimpedance amplifiers 556 and analog-to-digital converters 558 (as well as other related electrical components) are described above in connection with Figures 10A, 10B, 10C, 11, 12 and 13. It is noted that the size available for the detector elements is relatively small. Therefore, it is beneficial to provide an amplifier, such as a transimpedance amplifier. However, some amplifiers, such as a transimpedance amplifier, generally require a large resistance. Therefore, the circuit may comprise wiring routed between the cells, as described in connection with Figure 10A. This allows the signal to be amplified, resulting in less noise. Additionally or alternatively, pseudo resistors may be used in conjunction with transimpedance amplifiers and / or analog-to-digital converters, as described in connection with FIG. 12 or FIG.

[0167]

[0183] Although the above describes and shows an electrical insulation element 630 between the semiconductor element 610 and the charge base element 620, this is not necessary. For example, the semiconductor element 610 and the charge base element 620 may be in direct contact with each other. Furthermore, the semiconductor element 610 and the charge base element 620 may comprise at least one common component. For example, the lower metal layer 613 of the semiconductor element 610 may be part of the charge base element 620. For example, the metal layer 621 forming the detection surface of the charge base element 620 may also be the lower metal layer 613 of the semiconductor element 610. In such a configuration, preferably, good electrical insulation is provided between the detector circuitry for the charge base element and the detector circuitry for the semiconductor element. The advantage of the metal layer 621 forming the detection surface of the charge base element 620 and the lower metal layer 613 of the semiconductor element 610 is that a larger number of particles reach the pin region due to a smaller layer thickness for penetration (since a separate metal layer 621 and electrical insulation element 630 are not provided). This provides a lower energy threshold for 610. However, it should be noted that this configuration may make accurate charge measurements more difficult.

[0168]

[0184] Although the first and second energy thresholds are described above as being substantially the same, they may have an offset. In other words, the first energy threshold may be different from the second energy threshold. It should be noted that, for example, detection of signal particles near the threshold may result in detection of a variety of different types of signal particles, and it may be preferable to more clearly separate the detection of different signal particles. By having an offset between the first and second energy thresholds, the detected signal particles may be reduced, specifically, the amount of signal particles having border energy levels may be reduced, which may reduce noise in the detection. The first energy threshold may be above the second energy threshold. The first energy threshold may depend on the layer thickness before reaching the pin region. However, it can be adjusted to some extent by the bias voltage between the sample and the detector (as a different potential difference between the sample and the detector, which is further described below). If the bias voltage is, for example, +200V instead of +50V, in effect, the lower backscattered signal particles can gain enough additional kinetic energy to pass through these layers, thereby lowering the effective first energy threshold. The same happens for the second energy threshold. Thus, the value of the threshold can be influenced by the bias voltage, and thus the difference between the first and second threshold can be about 0-200V.

[0169]

[0185] From the above description of the second signal particles and backscattered signal particles, it will be understood that the threshold (e.g., 50V, or 100V, or 200V) between different types of signal particles is arbitrary. There is no clear division (i.e., clear separation) around this threshold. It is unlikely that the exact selection of the threshold is much to improve or contribute to the image contrast or image quality. Therefore, it is unlikely that the selection of the threshold reduces the detection of signal particles with border energy levels. In general, it is expected that the effective first and second energy thresholds may be different due to energy losses in the layers between the charge-based detector 621 and the pin region 611. A signal particle that has just enough energy to leave the charge-based detector 621 (i.e., above the first energy threshold) may lose too much energy in the layers between the charge-based detector 621 and the pin region 611 to reach the pin region 611. This leads to the second energy threshold having a different value than the first energy threshold.

[0170]

[0186] As mentioned above, an aperture 601 for the passage of the charged particle beam is defined in the substrate. This is beneficial in that the signal beam (e.g., primary beam 320) can pass through the detector 600, so that signal particles can be captured by the detector 600 throughout the entire primary beam. However, while this is beneficial, other configurations may be used. For example, the detector 600 may be provided on one side of the primary beam path. This allows the primary beam to reach the sample 208, and still the detector 600 can detect signal particles emitted from the sample 208. In this configuration, a Wien filter may be used in combination with the detector. In another configuration, the detector may be provided as at least two parts on either side of the path of the primary beam. The two parts may be separated by a gap. The two parts may be spaced apart. The gap may take the form of a slit or strip through which the path of the primary beam passes. If multiple primary beams (e.g., sub-beams) are provided, the detector may still be provided on one or both sides, for example with slits for the paths of multiple sub-beams of the multiple primary beams. In one configuration, such a detector array may have multiple detectors on one side of a slit. Such a configuration featuring slits between detectors or detector portions may be easier to manufacture. However, providing a detector with an aperture formed therein may be beneficial in allowing a large detection surface and therefore increased detection efficiency. Placing a detector on a lens electrode in an electrostatic lens may be more easily achieved if such a detector has an aperture rather than a slit or the like. It is noted that the aperture of the detector, the electrostatic field may cause some disturbance of the electric field, which may affect the primary sub-beam, and it is preferable if the disturbance of the sub-beam is symmetrical, as this reduces distortion due to aberrations.

[0171]

[0187] The above embodiments and variations may include slightly different configurations of the charge based elements 620 and the semiconductor elements 610 as shown in Figures 15 and 16. In this case, the charge based elements 620 may not form substantially the entire detection surface. In this case, the charge based elements 620 provide at least a portion of the detector surface and the semiconductor elements 610 provide at least a portion of the detector surface. In other words, the detector surface includes both the semiconductor elements 610 and the charge based elements 620.

[0172]

[0188] 15 and 16, the charge based element 620 and the semiconductor element 610 may be disposed adjacent to each other in a plan view. Thus, at least a portion of the charge based element 620 may be disposed substantially next to the semiconductor element 610 in a plan view, e.g., on the detection surface. It should be noted that a small gap may be provided between the charge based element 620 and the semiconductor element 610, and the gap may include, for example, an electrically insulating material.

[0173]

[0189] FIG. 15 shows an alternative in which the semiconductor element 610 and the charge base element 620 are stacked as described above in relation to FIG. 14. Specifically, the semiconductor element 610 and the charge base element 620 are stacked in cross section as in FIG. 14. However, in this embodiment, the charge base element 620 partially covers the semiconductor element 610. In this case, as shown in FIG. 15, the charge base element 620 may be disposed on the semiconductor surface 610 to form part of the detection surface. In other words, the charge base element 620 may partially overlap the semiconductor element 610. Thus, on the surface of the detector, there may be only a partial overlap of the charge base element on the semiconductor element 610. In this case, the charge base element 620 may be provided as an additional layer stacked on top of the semiconductor element 610 such that the complete semiconductor element is formed below the charge base element 620. Providing the charge base element 620 in this configuration, i.e. partially covering the semiconductor element 610, may be beneficial to reduce capacitance, resulting in a faster detector.

[0174]

[0190] Alternatively, as shown in FIG. 16, the charge base element 620 may be formed adjacent to the semiconductor element 610 to form part of the detection surface. In this case, the charge base element 620 and the semiconductor element 610 are formed adjacent to each other in cross section across the entire width of the detector (i.e., perpendicular to the direction of the primary beam, which can alternatively be referred to as the radial direction). In particular, the detection surface of the charge base element (provided by the metal layer 621) is adjacent to the detection surface of the semiconductor element (provided by the lower metal layer 613). That is, the detection surface of the charge base element (provided by the metal layer 621) is radially outside or inside the detection surface of the semiconductor element (provided by the lower metal layer 613). Thus, the charge base element does not overlap as a layer stacked on top of the semiconductor element. Instead, the semiconductor element 610 is formed surrounding the charge base element 620. In particular, there is no overlap of the charge base element on the lower metal layer 613. Instead, the lower metal layer 613 surrounds the charge-based element metal layer 621. In other words, the lower metal layer 613 is radially outside the metal layer 621 in the plane. The pin layer 611 may be formed through the detector and may be disposed below the charge-based element metal layer 621. This is beneficial because the same manufacturing process or process steps can be used for both the semiconductor element and charge-based element layers. As described above, an electrically insulating via 622 may connect the metal layer 621 to the detector circuitry through the pin layer. The semiconductor element may be separated and form part of the pin layer 611a associated with the charge-based element 620. The portion 611a of the pin layer associated with the charge-based element 620 does not participate in the operation of the semiconductor element 610. The portion 611a of the pin layer associated with the charge-based element 620 may be separated from the remainder of the pin layer by an insulating portion 623. The insulating portion 623 may be an electrically insulating member and may be similar to the electrically insulating element 630 described above, although having a different configuration. The insulating portion 623 may be disposed radially inward of the semiconductor element 610. The insulating portion 623 may be disposed radially outward of the charge base element 620.

[0175]

[0191] In this embodiment, the detector elements operate in a different mode. In particular, semiconductor elements can be used (shown in FIG. 16 as the outer ring), where the energy of higher energy signal particles (e.g., backscattered signal particles) is converted to electron-hole pairs in a depletion layer just below the detector surface. Lower energy signal particles (e.g., secondary signal particles) usually do not have enough kinetic energy to penetrate the upper layers of the detector (consisting of the lower metal layer 613 and the semiconductor dead layer). Therefore, lower energy signal particles are usually not detected by the semiconductor elements 620. It is beneficial to remove lower energy signal particles from the higher energy particle signal. This is because typically more lower energy signal particles are generated in the sample 208, and the lower energy particles will dominate over the higher energy particles if the different signal particles are not well separated. In this configuration, the crosstalk of the secondary signal particles to the semiconductor elements is expected to be very low or zero. Collector efficiency may be slightly lower than the stacked embodiment due to the reduced overall surface area for the sensing surfaces of both the semiconductor and charge base elements.

[0176]

[0192] The charge-based element 620 comprises a metal layer 621 (shown as an inner ring in FIG. 16) that acts as a charge conductor. This allows the secondary signal particles (and also the backscattered signal particles that impinge on this inner ring) to be detected by their charge. For better charge conduction, the thickness of the metal layer 621 on the charge-based element may be different from the lower metal layer 613 on the semiconductor element 610.

[0177]

[0193] Preferably, the metal layer 621 of the charge-based element 620 and at least the lower metal layer 613 of the semiconductor element are separated. Preferably, the metal layer 621 of the charge-based element 620 and at least the lower metal layer 613 of the semiconductor element have electrical insulation between them. Between the metal layer 621 and the lower metal layer 613 there is an insulating layer. This may be beneficial to avoid a direct interface between the two layers.

[0178]

[0194] It should be understood that the semiconductor and charge-based elements can be used to form the detector surface in a number of different configurations, and thus the separation of detection moieties in the overlapping and / or adjacent configurations described above can be similar to that described above in connection with Figures 6A and / or 6B.

[0179]

[0195] For example, the charge based element 620 and the semiconductor element 610 may each comprise an annulus (e.g., a ring) on ​​the detection surface. The annulus is preferably concentric and radially separated from one another. This is shown in cross section in Figures 15 and 16. Note that if the charge based element and the semiconductor element each form a single annulus, the detector surface may appear as shown in Figure 6A in plan view. In this example, the charge based element may correspond to the inner detection portion 405A and the semiconductor element may correspond to the outer detection portion 405B.

[0180]

[0196] For example, each of the charge base elements and the semiconductor elements may comprise at least one sector. For example, the detector surface may be formed by multiple sectors, which may be of approximately equal area. The sectors are preferably divided in an angular direction. Note that if each of the charge base elements and the semiconductor elements form two sectors, and the charge base elements and the semiconductor elements are interleaved, the detection surface may look as shown in FIG. 6B in plan view. In this case, the charge base element 620 may correspond to the detection portions 405C and 405E, and the semiconductor element 610 may correspond to the detection portions 405D and 405F.

[0181]

[0197] Although not shown, the charge based elements and the semiconductor elements may comprise at least one fan and at least one annulus. For example, the charge based elements and the semiconductor elements may form a checkerboard pattern or a dartboard pattern on the detector surface.

[0182]

[0198] The semiconductor element 610 may comprise multiple rings. The rings may be separated, for example, by a shape of electrically insulating member, which may or may not be part of the electrically insulating element 630 and / or insulating portion 623. The rings of each semiconductor element may be separated, for example, by insulating portion 623, as shown above in connection with FIG. 16. Providing the semiconductor element 610 as multiple rings may be beneficial when using an inner ring to detect high energy signal particles at smaller angles and an outer ring to detect high energy signal particles at larger angles. Thus, providing the semiconductor element as at least two rings allows for the detection of higher energy signal particles to be separated into different angular ranges, if desired.

[0183]

[0199] The detector described in any of the above variants can be operated with both deceleration and acceleration objective lenses (i.e., with devices operating in deceleration or acceleration modes). Specifically, when the detector is placed as a bottom detector (e.g., in the down beam of the objective lens array 241), the trajectory of the signal particles toward the detector is determined by the electric field between the sample and the detector, not by the deceleration or acceleration electric field of the objective lens. By applying a negative or positive bias to the detector or detector array with respect to the sample, low-energy signal particles (e.g., secondary signal particles) can be repelled (backscattering only mode) or attracted (combination of secondary and backscattering modes). It should be noted that typically, a higher landing energy is used for the acceleration lens. This means that in this case, high-energy signal particles (e.g., backscattering signal particles) have, on average, higher energy. This makes it easier for the high-energy signal particles to pass through the charge-based device 620 and the electrical insulation element 630. Therefore, in such a layered detector, high energy signal particles can more easily reach the semiconductor element 610. This detector type is more attractive for an accelerating lens.

[0184]

[0200] The detectors described above may be used in a single beam device, for example in combination with the device described in relation to FIG. 9. Alternatively, the detectors may be used in a multi-beam device, for example where the primary beam is split into sub-beams, for example as described in relation to FIGS. 3 and 8. Thus, multiple detectors may be provided, which may be suitable for use in a multi-beam charged particle device. The multiple detectors may be provided as described in any of the above variants or embodiments. The multiple detectors may form an array, which may be called a detector array. In this case, each detector may be configured as described above and may be arranged adjacent to other detectors in the array. Each detector may have the same configuration as each other, for example all detectors have the configuration of detector elements shown in FIG. 14, or the configuration shown in FIG. 15, or the configuration shown in FIG. 16.

[0185]

[0201] An array of detectors is shown in Figure 17 and variations of the array are shown in Figure 18. Note that the array of detectors shown in Figures 17 and 18 correspond to the detectors described above in relation to Figure 14. However, the detectors may have any of the variations described above, including those described in relation to Figures 15 or 16.

[0186]

[0202] The array of detectors may be arranged in any suitable configuration. Each detector may correspond to a respective sub-beam 320. For example, the array of detectors may correspond in configuration to the array of sub-beams of the multi-beam array described above. The arrangement may be a hexagonal (see, e.g., FIG. 10A) or linear grid. The detector array may have a plurality of apertures formed in the substrate, each aperture formed to correspond to a respective sub-beam in the multi-beam array. Thus, the apertures of the plurality of detectors may be for the passage of the sub-beams of the multi-beam array towards the sample 208.

[0187]

[0203] When an array of detectors is provided, multiple detectors may be provided on a substrate, which may be referred to as a common substrate (thus, in an embodiment where there is a single detector, the detector may be provided on a substrate). The substrate may comprise multiple semiconductor elements 610 and multiple charge base elements 620. Each semiconductor element 610 is associated with a corresponding one of the charge base elements 620. The same substrate may be provided for all detectors 600 in the array. Alternatively, multiple substrates may be provided in the detector array, each substrate comprising multiple semiconductor elements 610 and multiple charge base elements 620. The number of semiconductor elements 610 may correspond to the number of charge base elements 620.

[0188]

[0204] There may be detector components or layers that form a common layer, i.e. formed at the same location in each detector 600 of the array. For example, one of the components or layers (e.g., metal layer 621 of the charge-based element) may be formed at the same location along the primary beam path for each detector. In the case of metal layer 621, metal layer 621 may be formed as a detection layer for each detector forming the detector array.

[0189]

[0205] The semiconductor elements 610 of each detector may be in a common semiconductor layer of a substrate. Thus, the substrate may comprise a semiconductor detector layer comprising multiple semiconductor elements 610. The semiconductor layer may comprise components common to multiple detectors 600. For example, the pin regions 613 of the semiconductor elements may be a layer formed across multiple detectors, as shown in FIG. 17. The pin regions may be common to multiple detectors or even all detectors in a detector array. Alternatively, separate pin regions may be provided for each separate semiconductor element, and the pin regions may, for example, comprise an electrically insulating material between the semiconductor elements of different detectors in the array.

[0190]

[0206] Additionally or alternatively, the charge based elements 620 of each detector 600 may be in a common charge based layer of the substrate. Thus, a substrate may comprise a charge detector layer comprising a plurality of charge based elements.

[0191]

[0207] Additionally or alternatively, the electrical insulation elements between the charge base element 630 and the semiconductor element of each detector may be in a common electrical insulation layer of the substrate, and thus the substrate may further comprise an electrical insulation layer between the charge base element and the semiconductor element.

[0192]

[0208] Additionally or alternatively, the circuit layer 640 of each detector may be provided within a common circuit layer of the substrate. Thus, the substrate may comprise a circuit layer comprising a plurality of cells comprising circuitry associated with the charge base elements and / or semiconductor elements, for example as described and shown in Figures 10A, 10B and 10C. The detector may comprise one or more vias for each cell connecting the respective charge base element 620 and / or respective semiconductor element 610 to the circuitry of the cell. For example, each charge base element 620 may comprise an electrically insulating via 622 as described above, which connects from a corresponding one of the charge base elements 620 to the circuit layer 640. Each semiconductor element 610 may additionally or alternatively comprise a via for connection to the detector circuitry, or the semiconductor element may be directly connected to the detector circuitry by the upper metal layer 612.

[0193]

[0209] The circuit layer 640 may include a transimpedance amplifier and / or an analog-to-digital converter in each cell. Optionally, the circuit layer may include a transimpedance amplifier and / or an analog-to-digital converter for each charge based element 620 and / or each semiconductor element 610 of a corresponding cell. Thus, each of the charge based elements and / or semiconductor elements may be connected to a transimpedance amplifier and / or an analog-to-digital converter associated with the respective charge based element and / or semiconductor element.

[0194]

[0210] The detector array may comprise a shielding element 660, as shown in FIG. 18. The shielding element 660 may be an additional metal layer. The shielding element 660 may be arranged between the charge base element 620 and the semiconductor element 620 to avoid (or at least reduce) crosstalk effects between the two detector elements. More specifically, the shielding element 660 may be arranged between the metal layer 621 of the charge base element 620 and the lower metal layer 613 of the semiconductor element 610. This means that the signal particles have to travel through a thicker layer before reaching the detector 610, so this shielding element 660 is preferably as thin as possible. In addition, the electrical insulation element 630 may have portions on either side of the shielding element, for example thin portions 630A and 630B. The thin portions 630A, 630B may be protruding portions of the electrical insulation element 630. The thin portions 630A and 630B may be provided as thin films, or layers, or flat portions. Thus, there may be an electrically insulating portion 630A between the charge base element 620 and the shield element 660, and an electrically insulating portion 630B between the semiconductor element 610 and the shield element 660. Preferably, the electrically insulating portions 630A, 630B are also as thin as possible. The thin portions 630A, 630B may each have a thickness as described above with respect to the electrically insulating element 630, for example, the thickness of each portion 630A, 630B may be about 10-500 nm. The thickness may depend on the material, as described, and may optionally be SiO2. The shield element 660 may be used in any of the detectors described above, for example, as described in connection with Figures 14, 15 and / or 16.

[0195]

[0211] The detector array may further comprise a wiring layer. The wiring may be routed between the cells. Thus, the wiring layer may include the wiring routes 554 described above. The wiring layer may connect to the circuitry of the cells (e.g., associated with the single semiconductor element and the single charge-based element), for example, away from the apertures defined through the cell array as described above. The wiring layer may comprise shielding between the wiring connecting different cells. For example, the wiring layer may comprise a shielding configuration as shown in FIG. 13 and described above in connection with FIG. 13. The cells may only be connected to each other via the wiring of the wiring layer. The wiring layer may be formed between and around the cells. The wiring layer and the circuit layer may together form a single layered portion (where the wiring and the circuitry may occupy the maximum CMOS layer allowed by the CMOS architecture). Alternatively, the wiring layer and the circuit layer may each have their own respective layered portion. The wiring layer may form connections for the cells between the cells of the cell array. The wiring layer may connect the cells to the outside so that the detection signals of the detectors can be transmitted from the cells to external connections towards a processor for processing the detection signals. The circuitry and wiring of each cell is typically insulated, i.e. the cells are electrically insulated from each other. The wiring layer connects the associated detectors to a data path for transmission of the detection signals from the detector array in a manner that reduces the risk of destruction of the detection signals. The wiring for transmitting the detection signals to the outside is insulated to prevent crosstalk. The wiring layer and / or the circuit layer may form a monolithic layered portion of the substrate, configured to connect, for example, separately or together, to each detector of the detector array.

[0196]

[0212] As described above in connection with a single detector, the charge base elements 620 may be closer to the detection surface. Thus, the charge detector layer may be closer to the detection surface of the detector array than the corresponding semiconductor element layer. Each of the charge base elements 620 may overlap at least a portion of the corresponding semiconductor element 610. In one embodiment, the overlap is substantially complete, as shown in FIG. 17. Thus, the array may be based on a detector as shown in FIG. 14. In another embodiment, there may be only a partial overlap. In this case, the detection surface may be provided by the charge detector layer and the semiconductor detector layer. Thus, the array may be based on a detector 600 as shown in FIG. 15. In another embodiment, there may be no overlap. In this case, the detection surface may be provided by the charge detector layer and the semiconductor detector layer. Thus, the array may be based on a detector as shown in FIG. 16.

[0197]

[0213] Any of the detectors described above may be provided as part of a charged particle device for an evaluation tool to detect charged particles from a sample.

[0198]

[0214] The charged particle device may be a single beam device, for example as described in relation to FIG. 9, although other configurations may be used to provide a single beam device. The charged particle device may comprise an objective lens (e.g. of the objective lens assembly 132) configured to project a primary beam of charged particles onto the sample 208. The objective lens may be configured as described above. Preferably, an aperture is defined in the objective lens for the primary beam and an aperture is defined in the substrate of the detector 600, which is aligned with the aperture of the objective lens. As described above, however, the detector 600 may be provided on the side of the primary beam, such that the detector does not have an aperture formed through it. In this case, the detector 600 may still be aligned to the primary beam, for example by being positioned in the charged particle device proximate to the primary beam to detect signal particles emitted from the sample.

[0199]

[0215] The detector used in the charged particle device may be as described in any of the above embodiments and variations.

[0200]

[0216] A detector for use in a charged particle device may comprise a first detector element configured to detect signal particles above a first energy threshold and a second detector element configured to detect signal particles below a second energy threshold. In this case, the detector may be close to the sample and may comprise a semiconductor element. Thus, two different types of detectors may be provided near the sample, with the detector 600 comprising at least a semiconductor element. It is beneficial for the detector to be close to the sample, since at this location the energy difference between the lower and higher signal particles is larger than further up the beam (towards the source). At this position the magnitude of the energy difference may be at its maximum. In one configuration the ratio of energies is at its maximum. This assumes that the signal particles are not substantially accelerated towards the detector. However, there may be a potential difference applied to accelerate the signal particles towards the detector, which is further explained below.

[0201]

[0217] As mentioned above, in general it can be expected that the effective first and second energy thresholds will be different due to energy losses in the layers between the first and second detector elements.

[0202]

[0218] The first detector element may be a semiconductor element as detailed above, and the second detector element may be a charge-based element as detailed above.

[0203]

[0219] The charged particle device may be a multi-beam device, for example as described in relation to Figures 3 and 8, although other configurations may be used to provide a multi-beam device. The charged particle device may comprise an objective lens array 241 configured to project a plurality of sub-beams of charged particles onto the sample 208 in a multi-beam array. The objective lens array 241 may be configured as described above. The charged particle device may comprise a detector array as described above, or a detector system comprising a detector array as described above. Preferably, an aperture is defined in the objective lens array for each sub-beam, and an aperture is defined in each of the detectors of the detector array. Preferably, the aperture of at least one detector array is aligned with the aperture defined in the objective lens array 241.

[0204]

[0220] The detector may be associated with the objective lens array 241. For example, the detector may be structurally connected to the objective lens array 241. Thus, the detector may be disposed on the objective lens, attached to the objective lens, or directly connected to the objective lens. Specifically, the detector may be associated with a major surface of an electrode plate of the objective lens array 241. Thus, the detector may be structurally connected to an electrode of the objective lens array 241. The detector may be disposed adjacent to or structurally connected to the most down beam electrode of the objective lens array 241. The detector 600 may be disposed adjacent to or structurally connected to the down beam surface of the most down beam electrode of the objective lens array 241. The detector may be disposed adjacent to or structurally connected to the most up beam electrode of the objective lens array 241. If the detector is part of a detector array, the detector array and / or detector system may be associated with the objective lens array 241 as described herein.

[0205]

[0221] The detector 600 may be located at any suitable location of the charged particle device. The detector may provide a surface of the device. Preferably, the surface of the device is configured to face the sample. Preferably, the detector is close to the sample. Preferably, the detector is adjacent to the sample. Preferably, the detector is directly adjacent to the sample, with no other components between the detector and the sample. Providing the detector close to the sample is beneficial, since this improves the overall detection efficiency of lower and higher energy signal particles at the detector element at the same time. The detector 600 may be provided in the upbeam of the objective lens array 241 along the path of the primary beam 320. If the detector 600 is part of a detector array, the detector array and / or the detector system may be arranged as described herein.

[0206]

[0222] The device may be configured to apply a potential difference between the sample 208 and the detector array, for example, applied to at least a portion of the detector, such as, for example, a charged base element and / or a semiconductor-based element. The potential difference may be referred to as a bias voltage. For example, the potential may be relatively small. For example, the potential difference between the sample 208 and the detector array may be about 50V to 300V. The detector array may be at a higher positive potential than the sample. Thus, the potential difference may be used to attract the signal particles to the detector array. Such an acceleration voltage (e.g., about 50V to 300V) is small compared to the energy difference between lower energy signal particles (e.g., secondary signal particles with a maximum energy of about 50 eV) and higher energy signal particles (e.g., backscattered signal particles with a maximum energy up to a landing energy of several keV or more). It should be noted that a small potential difference tends to have a larger effect on particles of lower energy, e.g., particles corresponding to secondary signal particles. Of course, the same potential may be applied to a single detector when provided as part of a single beam device.

[0207]

[0223] Any of the detector configurations described above may have such a potential difference applied to attract signal particles, which may be beneficial as described above. Note that the use of this potential difference is particularly beneficial for detector configurations where the charge-based element partially covers the semiconductor element as shown in FIG. 15 or provides an inner ring as in FIG. 16. In this case, lower energy signal particles (e.g., secondary signal particles) can be accelerated upwards due to the resulting electric field between the sample and the detector. This may mean that the lower energy signal particles predominantly impinge on (or only impinge on) the charge-based element 621 formed as the inner ring of the concentric detector. It may therefore be advantageous to use only the charge-based elements on this inner ring, as this reduces charge generation by higher energy signal particles (e.g., backscattered signal particles) on the charge-based elements, reducing noise.

[0208]

[0224] In one configuration of the detector 600, at least one of the first element and the second element is a charge-based detector or a semiconductor detector. For example, the substrate of the detector 660 may comprise multiple layers, and the multiple layers may comprise the first element and the second element in different layers. The detector further comprises an electrical insulation element between the charge-based element and the semiconductor element. The detector may comprise two charge detector elements, and the two charge detector elements are configured to detect different signal particles and to detect simultaneously. Alternatively or in addition, the detector may comprise a charge-based element and a semiconductor element, and the semiconductor element and the charge-based element may be configured to detect simultaneously.

[0209]

[0225] In such a configuration of the detector, an aperture is defined in the substrate for the passage of the charged particle beam. The first energy threshold may correspond to a backscattering threshold energy. The second energy threshold may correspond to a secondary threshold energy. The first and second energy thresholds are substantially the same or have an offset. The at least one charge base element comprises a metal layer. The electrically insulating vias are configured to connect the charge base element to the detector circuit. Each of the charge base element and the semiconductor element is at least part of a layer that is substantially coplanar with a major surface of the detector. Each of the charge base element and the semiconductor element is at least part of a layer that is a stacked structure along the beam path. The detector array may comprise a plurality of such detectors. The detectors are provided on a common substrate. Each detector may correspond to a respective sub-beam of the multi-beam array. The apertures in the plurality of detectors are for the passage of the sub-beams. Such detectors and detector arrays may have features of other embodiments of detectors and detector arrays described herein.

[0210]

[0226] In an embodiment of the charged particle device, which may be for a multi-beam characterization system (or characterization tool) configured to detect charged particles from a sample. The device comprises an objective lens, e.g. as disclosed herein, and a detector, e.g. as disclosed herein. The objective lens array may be configured to project multiple beams of charged particles onto the sample. The detector may be proximate to the sample. The detector defines multiple apertures for paths of the beams towards the sample. In an embodiment, the detector comprises a first detector layer and a second detector layer. The first detector layer may be a first element. The second detector layer may be a second element. The first detector layer may be configured to detect signal particles above a first energy threshold, e.g. above a backscatter threshold energy. The second detector layer may be configured to detect signal particles below a second energy threshold, e.g. below a secondary threshold energy. At least one of the first detector layer and the second detector layer is a charge-based detector or a semiconductor detector. The second detector layer and the first detector layer are configured to detect simultaneously.

[0211]

[0227] The present invention may also provide a method of detecting signal particles using any of the detectors, detector arrays, or charged particle devices as described above.

[0212]

[0228] In one embodiment, a method is provided for projecting a beam of charged particles onto a sample 208 to detect signal particles emitted from the sample 208. The method includes projecting the beam along a primary beam path onto a surface of the sample 208. The method includes simultaneously detecting signal particles emitted from the sample at the semiconductor element and at the charge-based element.

[0213]

[0229] In one embodiment, a method is provided for projecting a beam of charged particles onto a sample 208 to detect signal particles emitted from the sample 208. The method includes projecting the beam along a primary beam path onto a surface of the sample. The method further includes detecting the signal particles emitted from the sample at a detector, the detector being proximate to the sample and comprising a semiconductor element, and the detecting includes simultaneous detection of signal particles above a first energy threshold at a corresponding first detector element and below a second energy threshold at a second detector element.

[0214]

[0230] In one embodiment, a method is provided for projecting multiple sub-beams of charged particles onto a sample 208 to detect signal particles emitted from the sample 208. The method includes projecting the sub-beams along primary sub-beam paths onto a surface of the sample 208. The method further includes detecting the signal particles emitted from the sample at a detector array, the detector array comprising a detector proximate to the sample and comprising a semiconductor element corresponding to each sub-beam, the detector comprising a first detector element and a second detector element, and the detecting includes simultaneous detection by each detector of signal particles above a first energy threshold at a corresponding first detector element and signal particles below a second energy threshold at a corresponding second detector element.

[0215]

[0231] In one embodiment, a method is provided for projecting a beam of charged particles onto a sample 208 to detect signal particles emitted from the sample. The method includes providing a device according to any of the embodiments or variations described above. The method further includes projecting the beam of charged particles onto the sample using an objective lens and simultaneously detecting the resulting signal particles using a semiconductor element 610 and a charge-based element 620.

[0216]

[0232] It will be understood that herein the charged / signal particles are generally intended to be electrons or other negatively charged particles. However, contrary to the above, the charged / signal particles may also be positively charged particles, e.g. ions. Thus, a primary ion beam may be provided. For the primary ion beam, secondary ions may be emitted from the sample, which may be detected by the charge-based element 620. However, this will also simultaneously generate negatively charged particles, e.g. secondary electrons. Thus, the charge stored by this charge-based element 620 will be a mix of positive and negative charged particles, which will make the measurement of charge unreliable. However, having either a positive or negative bias on the charge-based element 620 allows one of the charge polarities to be selected. Since the range of ions in materials is much smaller than electrons, backscattered ions require much more kinetic energy to be able to reach the semiconductor element 610. Thus, not all backscattered ions will make it to this detector component. To improve the detection of backscattered ions, the charge-based element 620 may be made thinner. If ions are used instead of negatively charged particles, then any biases referenced above would be reversed, e.g., a positive bias should be used instead of a negative bias.

[0217]

[0233] The terms "sub-beam" and "beamlet" are used interchangeably herein and are both understood to encompass any radiation beam derived from a parent radiation beam by splitting or separating the parent radiation beam. The term "manipulator" is used to encompass any element that affects the path of a sub-beam or beamlet, such as a lens or deflector. References to a number of elements being aligned along a beam path or sub-beam path are understood to mean that each element is located along the beam path or sub-beam path. References to optics are understood to mean electron optics.

[0218]

[0234] Although the description and drawings herein are directed to electron optical systems, it is understood that this embodiment is not used to limit the disclosure to a particular charged particle. Thus, throughout this specification, references to electrons may be considered as references to charged particles more generally, and not necessarily electrons. A charged particle optical device may be a negative charged particle device. A charged particle optical device may alternatively be referred to as an electron optical device. It will be understood that electrons are a particular charged particle, and all instances of charged particles referenced throughout this specification may be appropriately substituted. For example, a source may provide, among other things, electrons. Charged particles referenced throughout this specification may be, among other things, negative charged particles.

[0219]

[0235] The charged particle optical device may be more specifically defined as a charged particle optical column. In other words, the device may be provided as a column. The column may thus comprise an objective lens array assembly as described above. The column may thus comprise a charged particle optical system as described above, e.g. an objective lens array and an optional detector array and / or an optional collector lens array.

[0220]

[0236] The charged particle optical device described above comprises at least an objective lens array 240. The charged particle optical device may comprise a detector array 241. The charged particle optical device may comprise a control lens array 250. Thus, the charged particle optical device comprising the objective lens array and the detector array may be interchangeable with an objective lens array assembly and may be referred to as an objective lens array assembly, which may optionally comprise a control lens array 250. The charged particle optical device may comprise additional components as described in relation to either FIG. 3 and / or FIG. 8. Thus, when these figures include additional components, the charged particle optical device may be interchangeable with a charged particle evaluation tool 40 and / or a charged particle optical system and may be referred to as a charged particle evaluation tool 40 and / or a charged particle optical system.

[0221]

[0237] An evaluation tool according to an embodiment of the invention may be a tool that performs a qualitative measurement (e.g., pass / fail) of the specimen, a quantitative evaluation of the specimen (e.g., size of features), or a tool that generates an image of a map of the specimen. Examples of evaluation tools are inspection tools (e.g., to identify defects), review tools (e.g., to classify defects), and metrology tools, or tools capable of performing any combination of evaluation functions associated with an inspection tool, a review tool, or a metrology tool (e.g., metrology inspection tool). The charged particle beam tool 40 (which may be a charged particle optical column) may be a component of an evaluation tool, e.g., an inspection tool or a metrology inspection tool, or part of an electron beam lithography tool. Any reference to a tool in this specification is intended to encompass a device, an apparatus, or a system, which may comprise various components, which may or may not coexist and may even be located in separate rooms, in particular with respect to, e.g., data processing elements.

[0222]

[0238] Reference to a component or a system of components or elements being controllable to manipulate the charged particle beam in a particular manner includes configuring a controller or control system or control unit to control the component to manipulate the charged particle beam in the described manner, as well as, optionally, using other controllers or devices (e.g., voltage supplies and / or current supplies) to control the component to manipulate the charged particle beam in this manner. For example, a voltage supply may be electrically connected to one or more components to apply a potential to the components, including, for example, as a non-limiting list, the control lens array 250, the objective lens array 241, the condenser lens 231, the corrector, the collimator element array 271, the detector array 240, the stage 209 (and thus, for example, the sample 207), and the scan deflector array 260. Such a voltage supply may be under the control of a controller or control system or control unit. The voltage supply may apply a potential difference, for example, a bias voltage, to at least a portion of the detector (or detector array), for example, with respect to the sample 207. Such bias voltages may be controlled, for example, by a control system, such as by the controller 50. An actuatable component, such as a stage, may be controllable to be actuated and thus moved relative to another component, such as a beam path, using one or more controllers, control systems or control units for controlling the actuation of the component.

[0223]

[0239] The embodiments described herein may take the form of a series of aperture arrays or charged particle optical elements arranged in an array along the beam or multi-beam path. Such charged particle optical elements may be electrostatic. In an embodiment, all the charged particle optical elements, e.g., from the beam limiting aperture array to the last charged particle optical element in the sub-beam path before the sample, may be electrostatic and / or in the form of aperture arrays or plate arrays. In some configurations, one or more of the charged particle optical elements are fabricated as a microelectromechanical system (MEMS) (i.e., using MEMS fabrication techniques).

[0224]

[0240] 3 and 8 and described above, may include components such as an upper beam limiter, a collimator element array 271, a control lens array 250, a scanning deflector array 260, an objective lens array 241, a beam shaping limiter, and / or a detector array 240. One or more of these elements present may be connected to one or more adjacent elements with isolation elements such as ceramic or glass spacers.

[0225]

[0241] The computer program may include instructions to instruct the controller 50 to perform the following steps: The controller 50 controls the charged particle beam device to project the charged particle beam towards the sample 208. In one embodiment, the controller 50 controls at least one charged particle optical element (e.g., an array of multiple deflectors or scanning deflectors 260, 265) to affect the charged particle beam in the charged particle beam path. Additionally or alternatively, in one embodiment, the controller 50 controls at least one charged particle optical element (e.g., a detector array 240) to affect the charged particle beam emitted from the sample 208 in response to the charged particle beam.

[0226]

[0242] Any element or collection of elements in the charged particle beam tool 40 may be replaceable or on-site replaceable. One or more of the charged particle optical components in the charged particle beam tool 40, particularly those that act on or generate sub-beams, such as aperture arrays and manipulator arrays, may comprise one or more MEMS.

[0227]

[0243] While the invention has been described in conjunction with various embodiments, other embodiments of the invention will become apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims and clauses.

[0228]

[0244] The following provisions are provided: Clause 1: A detector for use in a charged particle device for an evaluation tool for detecting signal particles from a sample, the detector comprising or provided within a substrate, the substrate comprising a semiconductor element configured to detect signal particles above a first energy threshold and a charge-based element configured to detect signal particles below a second energy threshold, preferably the charged particle device is configured to project a beam of charged particles onto the sample, preferably the detector is configured to detect resultant signal particles, preferably the resultant signal particles include signal particles above the first energy threshold and preferably the resultant signal particles include signal particles below the second energy threshold.

[0229]

[0245] Clause 2: A detector as described in clause 1, wherein an aperture for the passage of the charged particle beam (or of each charged particle sub-beam) is defined in the substrate.

[0230]

[0246] Clause 3: A detector as described in clause 1 or 2, further comprising an electrically insulating element between the charge base element and the semiconductor element.

[0231]

[0247] Clause 4: A detector according to any one of clauses 1 to 3, wherein the first energy threshold corresponds to a backscatter threshold energy.

[0232]

[0248] Clause 5: A detector according to any preceding clause, wherein the second energy threshold corresponds to a secondary threshold energy.

[0233]

[0249] Clause 6: A detector according to any preceding clause, wherein the first energy threshold and the second energy threshold are substantially the same or have an offset.

[0234]

[0250] Clause 7: A detector according to any preceding clause, wherein the charge-based element comprises a metal layer.

[0235]

[0251] Clause 8: A detector as described in any preceding clause, further comprising an electrically insulating via configured to connect the charge base element to a detector circuit, preferably wherein the substrate comprises a circuit layer comprising the detector circuit.

[0236]

[0252] Clause 9: The detector of clause 8, wherein the electrically insulating via extends through at least a portion of the semiconductor element.

[0237]

[0253] Clause 10: A detector as described in any preceding clause, wherein the semiconductor element comprises an upper metal layer and a lower metal layer on each side of the pin region.

[0238]

[0254] Clause 11: The detector of clause 10, wherein the lower metal layer is also part of the charge base element.

[0239]

[0255] Clause 12: A detector according to clause 10 or 11, wherein the upper metal contact is preferably connected to a detector circuit provided in a circuit layer of the substrate.

[0240]

[0256] Clause 13: A detector described in any of the preceding clauses, wherein each of the charge base element and the semiconductor element is at least part of a layer that is substantially coplanar with a main surface of the detector, and the layers are provided in a laminate structure provided within the detector, stacked in the thickness direction of the detector.

[0241]

[0257] Clause 14: A detector according to any preceding clause, wherein the charge-based detector element forms a layer substantially throughout the semiconductor element.

[0242]

[0258] Clause 15: A detector described in any of the preceding clauses, wherein the charge-based element is closer to the detector surface (or an individual detector surface) than the semiconductor element, and preferably the charge-based element provides at least a portion of the detector surface (or an individual detector surface).

[0243]

[0259] Clause 16: A detector described in any one of clauses 1 to 12, wherein the charge base element and the semiconductor element are arranged adjacent to each other in cross section, preferably the charge base element provides at least a portion of the detector surface (or an individual detector surface) and the semiconductor element provides at least a portion of the detector surface (or an individual detector surface).

[0244]

[0260] Clause 17: A detector as described in clause 16, wherein the charge-based element and the semiconductor element each comprise annular rings radially separated from one another, preferably concentrically.

[0245]

[0261] Clause 18: A detector as claimed in claim 16 or 17, wherein the charge based elements and the semiconductor elements each comprise sectors, preferably angularly divided.

[0246]

[0262] Clause 19: A detector according to any preceding clause, wherein the charge-based element has a thickness of about 100 nm or less, preferably between about 10 nm and 100 nm.

[0247]

[0263] Clause 20: A detector as described in any of the preceding clauses, wherein the charge base element is connected to a transimpedance amplifier, preferably in a circuit layer, and / or the semiconductor element is connected to a transimpedance amplifier, preferably in a circuit layer, and / or further comprising a shielding layer 660 arranged between the charge base element and the semiconductor element, preferably having electrical insulation portions between the charge base element and the shielding layer, and between the semiconductor element and the shielding layer.

[0248]

[0264] Clause 21: A detector for use in a charged particle device, the detector comprising a substrate, the substrate comprising a first element configured to detect signal particles above a first energy threshold and a second element configured to detect signal particles below a second energy threshold, at least one of the first element and the second element being a charge-based detector or a semiconductor detector.

[0249]

[0265] Clause 22: A detector as described in Clause 21, wherein the substrate comprises a plurality of layers, the plurality of layers comprising the first element and the second element in different layers, and / or the detector further comprises an electrically insulating element between the charge base element and the semiconductor element.

[0250]

[0266] Clause 23: A detector according to clause 21 or 22, wherein the detector comprises two charge detector elements, the two charge detector elements being configured to detect different and simultaneously detect signal particles.

[0251]

[0267] Clause 24: A detector according to any of clauses 21 to 23, wherein the detector comprises a charge-based element and a semiconductor element, the semiconductor element and the charge-based element being configured for simultaneous detection.

[0252]

[0268] Clause 25: A detector according to any of clauses 21 to 24, wherein an aperture for the passage of the charged particle beam is defined in the substrate.

[0253]

[0269] Clause 26: A detector according to any of Clauses 21 to 25, wherein the first energy threshold corresponds to a backscatter threshold energy.

[0254]

[0270] Clause 27: A detector according to any of clauses 21 to 26, wherein the second energy threshold corresponds to a secondary threshold energy.

[0255]

[0271] Clause 28: A detector according to any of clauses 21 to 27, wherein the first energy threshold and the second energy threshold are substantially the same or have an offset.

[0256]

[0272] Clause 29: A detector according to any of clauses 21 to 28, wherein at least one of the charge-based elements comprises a metal layer.

[0257]

[0273] Clause 30: A detector according to any of clauses 21 to 29, further comprising an electrically insulating via configured to connect the charge base element to a detector circuit.

[0258]

[0274] Clause 31: A detector described in any of clauses 21 to 30, wherein each of the charge base element and the semiconductor element is at least part of a layer that is substantially coplanar with a main surface of the detector and is a stacked structure along the beam path.

[0259]

[0275] Clause 32: A detector described in any of clauses 21 to 31, wherein the detectors are provided in a common substrate, each detector corresponding to a respective sub-beam of the multi-beam array, and the apertures of the multiple detectors are for the passage of the sub-beams.

[0260]

[0276] Clause 33: A detector array comprising a plurality of detectors according to any of the preceding clauses, the detectors being provided in a common substrate, each detector corresponding to a respective sub-beam, preferably wherein a) the semiconductor elements of each detector are in a common semiconductor layer of the substrate, b) the charge base elements of each detector are in a common charge base layer of the substrate, c) the circuit layer of each detector is provided in the common circuit layer of the substrate, d) the electrical insulation elements between the charge base elements and the semiconductor elements of each detector are in the common electrical insulation layer of the substrate, e) the detectors are arranged in an array in a configuration corresponding to the array of the sub-beams of the multi-beam array, which configuration may be a hexagonal or rectilinear grid, and / or f) the apertures of the plurality of detectors are for the passage of a sub-beam of the multi-beam array.

[0261]

[0277] Clause 34: A detector array for use in a multi-beam charged particle device for an evaluation tool for detecting signal particles from a sample, the detector array comprising at least one substrate having a plurality of apertures defined within the substrate for passing a plurality of sub-beams of a charged particle beam towards the sample, the substrate comprising a plurality of semiconductor elements configured to detect signal particles above a first energy threshold and a plurality of charge-based elements configured to detect signal particles below a second energy threshold, each semiconductor element being associated with a corresponding one of the charged-based elements.

[0262]

[0278] Clause 35: A detector array as described in clause 34, wherein the substrate comprises a semiconductor detector layer comprising a plurality of semiconductor elements.

[0263]

[0279] Clause 36: A detector array as described in clause 34 or 35, wherein the substrate comprises a charge detector layer comprising a plurality of charge based elements.

[0264]

[0280] Clause 37: A detector array as described in clause 36, wherein the charge-based element comprises a metal layer.

[0265]

[0281] Clause 38: A detector array as described in clause 36 or 37, wherein the charge detector layer is closer to a detection surface of the detector array than the corresponding semiconductor element, the detection surface being a surface of the detector array for passage of signal particles to the semiconductor element or the charged base element.

[0266]

[0282] Clause 39: A detector array described in any one of clauses 36 to 38, wherein each of the charged base elements overlaps at least a portion of a corresponding semiconductor element, preferably the overlap is substantially complete.

[0267]

[0283] Clause 40: A detector array according to any one of clauses 36 to 38, wherein the charge-based elements and the semiconductor elements are arranged adjacent to each other, for example in cross section.

[0268]

[0284] Clause 41: A detector described in any one of the preceding clauses, wherein the substrate further comprises an electrically insulating element between the charge base element and the semiconductor element.

[0269]

[0285] Clause 42: A detector array described in any one of the preceding clauses, wherein the substrate further comprises a circuit layer comprising a plurality of cells comprising circuits associated with the charged base elements and / or the semiconductor elements.

[0270]

[0286] Clause 43: A detector array as described in clause 42, further comprising one or more vias for each cell connecting each charged base element and / or each semiconductor element to the cell's circuitry.

[0271]

[0287] Clause 44: A detector array as described in Clause 43, wherein the circuit layer comprises a transimpedance amplifier and / or an analog-to-digital converter within each cell, and optionally for each charged base element and / or each semiconductor element of the corresponding cell.

[0272]

[0288] Clause 45: A detector array as described in clause 44, further comprising a wiring layer, the wiring layer comprising wiring connecting the circuits of the spaced apart cells from the plurality of apertures.

[0273]

[0289] Clause 46: A detector array as described in clause 45, wherein wiring is routed between the cells.

[0274]

[0290] Clause 47: A detector array as described in clause 45 or 46, wherein the wiring comprises shielding between the wiring connecting different cells.

[0275]

[0291] Clause 48: A charged particle device for a multi-beam evaluation system for detecting charged particles from a sample, the device comprising: an objective lens array configured to project multiple beams of charged particles onto the sample; and a detector proximate to the sample, the detector defining multiple apertures for paths of the beams towards the sample, the detector comprising a first detector layer for detecting signal particles above a first energy threshold and a second detector layer for detecting signal particles below a second energy threshold, at least one of the first detector layer and the second detector layer being a charge-based detector or a semiconductor detector, and / or the second detector layer and the first detector layer being configured for simultaneous detection.

[0276]

[0292] Clause 49: A charged particle device for an evaluation tool for detecting signal particles from a sample, the device comprising an objective lens configured to project a beam of charged particles onto the sample and a detector described in any of clauses 1 to 32.

[0277]

[0293] Clause 50: A charged particle device as described in clause 49, wherein an aperture is defined in an objective lens for the beam and an aperture is defined in a substrate of the detector, the aperture being aligned with the aperture of the objective lens.

[0278]

[0294] Clause 51: A charged particle device for an evaluation tool for detecting signal particles from a sample, the device comprising an objective lens array configured to project multiple sub-beams of charged particles onto the sample in a multi-beam array, an aperture being defined for each sub-beam, and a detector system comprising at least one detector array as described in any one of clauses 19 to 47, the aperture of the at least one detector array being aligned with the aperture defined in the objective lens array.

[0279]

[0295] Clause 52: A charged particle device as described in Clause 51, wherein at least one detector of the detector system is structurally connected to the objective lens.

[0280]

[0296] Clause 53: A charged particle device described in clause 51 or 52, wherein at least one detector is associated with a main surface of an electrode plate of the objective lens.

[0281]

[0297] Clause 54: A charged particle device according to any of clauses 49 to 53, wherein at least one detector is preferably configured to face the sample and / or provides a surface of the device such that the detector (or at least one detector) is in close proximity to the sample.

[0282]

[0298] Clause 55: A charged particle device according to any of clauses 49 to 54, wherein at least one detector is provided in the up beam along the paths of the multiple sub-beams of the objective lens.

[0283]

[0299] Clause 56: A charged particle device for an evaluation tool for detecting charged particles from a sample, the device comprising: an objective lens configured to project a beam of charged particles onto the sample, the objective lens defining an aperture for the beam; and a detector proximate to the sample and defining an aperture aligned with the aperture of the objective lens, the detector comprising a first detector element configured to detect signal particles above a first energy threshold and a second detector element configured to simultaneously detect signal particles below a second energy threshold, the detector comprising a semiconductor element.

[0284]

[0300] Clause 57: A charged particle device as described in Clause 56, wherein the first detector element comprises a semiconductor element.

[0285]

[0301] Clause 58: A charged particle device described in any of clauses 56 or 57, wherein the second detector element comprises a charge-based detector element.

[0286]

[0302] Clause 59: The detector is a charged particle device according to clause 58, according to any one of clauses 1 to 32.

[0287]

[0303] Clause 60: A charged particle device according to any one of clauses 49 to 59, wherein the device is configured to apply a potential difference between the sample and the detector.

[0288]

[0304] Clause 61: A charged particle device as described in Clause 60, wherein the potential difference between the sample and the detector is approximately 50V to 300V.

[0289]

[0305] Clause 62: A charged particle device described in either clause 60 or 61, wherein the detector has a higher positive voltage than the sample.

[0290]

[0306] Clause 63: A charged particle device described in any of Clauses 48 to 62, further comprising a voltage supply unit electrically connected to one or more components and configured to apply a potential to the components, and preferably further comprising a controller configured to control the voltage supply unit.

[0291]

[0307] Clause 64: A charged particle device as described in Clause 63, wherein the voltage supply is configured to apply a bias voltage to at least a portion of the detector (or detector array), preferably, for example, the detector between the detector (or detector array) and the sample.

[0292]

[0308] Clause 65: A charged particle evaluation tool comprising a charged particle device according to any one of clauses 48 to 64, preferably the charged particle evaluation tool being for evaluating the sample by detecting signal particles from the sample using a charged particle device that projects multiple beams of charged particles towards the sample.

[0293]

[0309] Clause 66: An evaluation tool according to clause 65, comprising a stage configured to support a sample, preferably comprising a sample holder configured to hold the sample.

[0294]

[0310] Clause 67: A method for projecting a beam of charged particles onto a sample to detect signal particles emitted from the sample, the method comprising: a) projecting the beam along a primary beam path onto a surface of the sample; and b) simultaneously detecting signal particles emitted from the sample at a semiconductor element and at a charge-based element.

[0295]

[0311] Clause 68: A method for projecting a beam of charged particles onto a sample to detect signal particles emitted from the sample, the method comprising: a) projecting the beam along a primary beam path onto a surface of the sample; and b) detecting signal particles emitted from the sample at a detector, the detector being proximate to the sample and comprising a semiconductor element, the detecting including simultaneous detection of signal particles above a first energy threshold in a corresponding first detector element and below a second energy threshold in a second detector element.

[0296]

[0312] Clause 69: A method for projecting multiple sub-beams of charged particles onto a sample to detect signal particles emitted from the sample, the method comprising: a) projecting the sub-beams along a main sub-beam path onto a surface of the sample; and b) detecting signal particles emitted from the sample in a detector array, the detector array comprising a detector adjacent to the sample and comprising a semiconductor element corresponding to each sub-beam, the detector comprising a first detector element and a second detector element, and the detecting comprises simultaneous detection by each detector of signal particles above a first energy threshold in a corresponding first detector element and signal particles below a second energy threshold in the second detector element.

[0297]

[0313] Clause 70: A method for projecting a beam of charged particles onto a sample to detect signal particles emitted from the sample, the method comprising providing a device described in any one of clauses 48 to 53, projecting the beam of charged particles onto the sample using an objective lens, and simultaneously detecting the resulting signal particles using a semiconductor element and a charge-based element.

Claims

1. A charged particle evaluation tool for evaluating by detecting signal particles from a sample using a charged particle device that projects a multi-beam of charged particles toward the sample, the evaluation tool comprising a detector array comprising a plurality of detectors configured to detect signal particles from the sample, the plurality of detectors being provided in a substrate, each detector corresponding to a respective sub-beam, and the individual detectors of the substrate being a semiconductor element configured to detect signal particles exceeding a first energy threshold, a charge-based element configured to detect signal particles below a second energy threshold, and a charged particle evaluation tool.

2. The charged particle evaluation tool according to claim 1, wherein an aperture for passage of each respective sub-beam of charged particles is defined in the substrate.

3. The charged particle evaluation tool according to claim 1 or 2, further comprising an electrical insulation element between the charge-based element and the semiconductor element.

4. The charged particle evaluation tool according to claim 1 or 2, wherein the first energy threshold corresponds to a backscattering threshold energy.

5. The charged particle evaluation tool according to claim 1 or 2, wherein the second energy threshold corresponds to a secondary threshold energy.

6. The charged particle evaluation tool according to claim 1 or 2, wherein the first energy threshold and the second energy threshold are substantially the same or have an offset.

7. The charged particle evaluation tool according to claim 1 or 2, wherein the charge-based element comprises a metal layer.

8. The charged particle evaluation tool according to claim 1 or 2, further comprising an electrical insulation via configured to connect the charge-based element to a detector circuit, and preferably, the substrate comprises a circuit layer comprising the detector circuit.

9. The charged particle evaluation tool according to claim 1 or 2, wherein the semiconductor element comprises an upper metal layer and a lower metal layer on each side of the p-i-n region.

10. The charged particle evaluation tool according to claim 9, wherein the lower metal layer is also part of the charge-based element and / or the upper metal contact is preferably connected to a detector circuit provided in the circuit layer of the substrate.

11. Each of the charge-based element and the semiconductor element is at least part of a layer that is in a substantially same plane as a main surface of the detector, and the layer is provided in a stacked structure provided in the detector and stacked in a thickness direction of the detector. The charged particle evaluation tool according to claim 1 or 2.

12. The charged particle evaluation tool according to claim 1 or 2, wherein the charge-based detector element forms a layer substantially over the entire semiconductor element.

13. The charged particle evaluation tool according to claim 1 or 2, wherein the charge-based element is closer to an individual detector surface than the semiconductor element, and preferably, the charge-based element provides at least part of the individual detector surface.

14. The charged particle evaluation tool according to claim 1 or 2, wherein the charge-based element and the semiconductor element are arranged adjacent to each other in a cross section, and preferably, the charged particle-based element provides at least part of the individual detector surface, and the semiconductor element provides at least part of the individual detector surface.

15. The charged particle evaluation tool according to claim 14, wherein each of the charge-based element and the semiconductor element preferably includes an annular ring radially divided from each other in a concentric shape, and / or each of the charge-based element and the semiconductor element preferably includes a sector divided in an angular direction.

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