Charged particle device, charged particle projection method, and sample evaluation method

Abstract

The present disclosure relates to a charged particle device for projecting a plurality of beams of charged particles toward a sample. In one arrangement, a sample support supports a sample. A charged particle optical device projects a plurality of beams of charged particles to a sample along a plurality of paths. The apparatus includes a plurality of charged particle optical elements defining an objective lens, and a plurality of apertures are defined in the plurality of charged particle optical elements along a path of the beam. At least two of the charged particle optical elements are configured to be disposed at different potentials, and at least one of the charged particle optical elements is disposed at a ground potential.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims priority to EP application 22215815.6 filed on Dec. 22, 2022 and EP application 23155518.6 filed on Feb. 8, 2023, the entire contents of both applications being incorporated herein by reference. Technical Field

[0003] The embodiments provided herein generally relate to devices for guiding charged particles, such as electrons, to a sample, as well as related devices and methods. Background Art

[0004] When manufacturing semiconductor integrated circuit (IC) chips, during the manufacturing process, unwanted pattern defects may occur on a substrate (e.g., a wafer) or a mask, thereby reducing the yield. The defects may be due to optical effects and incident particles or other processing steps such as etching, deposition, or chemical mechanical polishing. Therefore, monitoring the extent of unwanted pattern defects is an important process in IC chip manufacturing. More generally, inspecting and / or measuring the surface of a substrate or other object / material is an important process during and / or after its manufacturing process.

[0005] Pattern evaluation systems (e.g., pattern inspection tools with a charged particle beam) have been used to evaluate objects, such as detecting pattern defects. These tools typically use electron microscopy techniques, such as scanning electron microscopy (SEM). In SEM, a primary electron beam at a relatively high energy undergoes a final deceleration step to land on a target at a relatively low landing energy. The electron beam is focused as a probe point on the target. The interaction between the material structure at the probe point and the landing electrons in the electron beam causes electrons to be emitted from the surface, such as secondary electrons, backscattered electrons, or Auger electrons, which may be collectively referred to as signal electrons or more generally as signal particles. The generated secondary electrons can be emitted from the material structure of the target.

[0006] By scanning the primary electron beam as a probe point over the target surface, secondary electrons can be emitted across the surface of the target. By collecting these emitted secondary electrons from the target surface, a pattern inspection tool (or device) can acquire an image-like signal representing the characteristics of the material structure of the surface of the target. In such an inspection, the collected secondary electrons are detected by a detector within the device. The detector generates a signal in response to the incident charged particles. When inspecting a region of a sample, the signal includes data that is processed to generate an inspection image corresponding to the inspected region of the sample.

[0007] By applying an electric potential to a charged particle optical element, a charged particle beam such as an electron beam can be controlled. The electric potential defines an electric field, which can be used to affect the trajectory of charged particles in a desired manner, such as deflecting or focusing the charged particle beam. In cases where the electric field is large, such as when the charged particle optical element is close to the sample, or when different charged particle optical elements are close together, or when a high potential difference is applied, the electric field may trigger a discharge event due to electrical breakdown. Such a discharge can cause voltage and current fluctuations in nearby components, leading to damage to these components. Discharge protection elements such as diodes can provide protection against such damage, but may increase system complexity and / or degrade noise performance. SUMMARY OF THE INVENTION

[0008] An object of the present disclosure is to at least partially address the operating characteristics of the above-mentioned charged particle optical elements, including, for example, reducing or avoiding the risk of component damage caused by discharge.

[0009] According to one aspect of the present invention, there is provided a charged particle device for projecting a multi-beam of charged particles onto a sample, the device comprising: a sample support configured to support the sample; a charged particle optical device configured to project a multi-beam of charged particles onto the sample along a plurality of paths, the device including a plurality of charged particle optical elements that define an objective lens, and a plurality of apertures are defined along the path of the beam in the plurality of charged particle optical elements, wherein: at least two of the charged particle optical elements are configured to be set at different electric potentials, and at least one of the charged particle optical elements is set at ground potential.

[0010] According to one aspect of the present invention, there is provided a method of projecting charged particles onto a sample, the method comprising: using a charged particle optical device to project a multi-beam of charged particles onto the sample along a plurality of paths, the device including a plurality of charged particle optical elements that define an objective lens, and a plurality of apertures are defined along the path of the beam in the plurality of charged particle optical elements; and during the projection of the beam onto the sample, maintaining at least two of the charged particle optical elements at different electric potentials, and maintaining at least one of the charged particle optical elements at ground potential.

[0011] The advantages of the present invention will become apparent from the following description in conjunction with the accompanying drawings, in which certain embodiments of the present invention are illustrated by way of illustration and example. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and other aspects of the present disclosure will become more apparent from the description of exemplary embodiments in conjunction with the accompanying drawings.

[0013] Figure 1 It is a schematic diagram showing an exemplary evaluation device.

[0014] Figure 2 It is a schematic diagram showing an exemplary multi-beam charged particle optical device that is part of an exemplary evaluation device as Figure 1 shown.

[0015] Figure 3 It is a schematic diagram of an exemplary charged particle optical device that includes an array of collimator elements and an array of scan deflectors, and the scan deflector array is Figure 1 part of an exemplary evaluation device as

[0016] Figure 4 It is a schematic diagram of an exemplary array of charged particle optical devices that includes a charged particle optical device having Figure 3 as shown.

[0017] Figure 5 It is a schematic diagram of an alternative exemplary charged particle optical device that is part of an exemplary evaluation device as Figure 1 shown.

[0018] Figure 6 It is a schematic diagram of an alternative exemplary charged particle optical device that is part of an exemplary evaluation device as Figure 1 shown.

[0019] Figure 7 It is a schematic diagram of an exemplary charged particle optical module that can be part of a charged particle optical device that can be Figure 3 , Figure 4 , Figure 5 or Figure 6 as shown.

[0020] Figure 8 It is a schematic cross-sectional view of a first spacer element of a charged particle optical module taken along an axis parallel to the path of the beams of a multi-beam and passing through Figure 7 as shown.

[0021] Figure 9 It is Figure 7 an enlarged view of a part of a charged particle optical module as shown.

[0022] Figures 10 - 12 It is Figure 7 an enlarged view of a part of a charged particle optical module as shown, which shows different exemplary configurations of vias passing through a detector substrate.

[0023] Reference will now be made in detail to exemplary embodiments, which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings in which the same numbers in different drawings represent the same or similar elements unless otherwise noted. The implementations set forth in the description of the following exemplary embodiments do not represent all implementations consistent with the present invention. On the contrary, they are merely examples of apparatuses and methods consistent with aspects related to the present invention as recited in the appended claims. Detailed Description

[0024] By significantly increasing the packaging density of circuit components such as transistors, capacitors, diodes, etc. on an IC chip, it is possible to achieve a reduction in the physical size of the device and an enhancement in the computing power of the electronic device. This can be achieved by increasing the resolution to fabricate smaller structures. Semiconductor IC manufacturing is a complex and time-consuming process with hundreds of individual steps. Errors in any step of the IC chip manufacturing process have the potential to adversely affect the functionality of the final product. Just one defect can lead to device failure. It is desirable to increase the overall yield of the process. For example, in order to achieve a 75% yield in a 50-step process (where one step can indicate the number of layers formed on the wafer), each individual step must have a yield greater than 99.4%. If the yield of an individual step is 95%, the overall yield of the entire process will be as low as 7-8%.

[0025] It is also desirable to maintain a high substrate (i.e., wafer) throughput (defined as the number of substrates processed per hour). The presence of defects can affect high process yield and high substrate throughput. This is especially true if operator intervention is required to inspect for defects. High-throughput detection and identification of micron- and nano-scale defects by an evaluation system such as a scanning electron microscope (SEM) is desirable for maintaining a high yield and low cost of IC chips.

[0026] A scanning electron microscope includes a scanning device and a detector device. The scanning device includes an irradiation device, which includes an electron source for generating primary electrons and a projection device for scanning a target (such as a substrate) with one or more focused primary electron beams. The primary electrons interact with the target and generate interaction products, such as signal particles, for example, secondary electrons and / or backscattered electrons. The secondary electrons can be considered to have an energy of up to 50 eV. Although the backscattered electrons have an energy spectrum ranging from essentially zero to the maximum energy of the charged particle device, they are typically set as electrons (or signal electrons) having an energy exceeding 50 eV. When the target is scanned, the detector device captures signal particles (e.g., secondary electrons and / or backscattered electrons) from the target so that the scanning electron microscope can create an image of the scanned area of the target. The design of the charged particle optical device that implements these scanning electron microscope features can have a single beam. To obtain higher throughput, such as for evaluation, some device designs use multiple focused primary electron beams, i.e., multiple beams of primary electrons. The component light waves of the multiple beams can be referred to as sub-beams or beam waves. The multiple beams can scan different parts of the target simultaneously. Therefore, a multiple-beam evaluation device can evaluate the target faster than a single-beam evaluation device, for example, by moving the target at a higher speed.

[0027] A known implementation of a multiple-beam evaluation device is described below.

[0028] The drawings are schematic. Therefore, for clarity, the relative sizes of the components in the drawings are exaggerated. In the following description of the drawings, the same or similar reference numerals refer to the same or similar components or entities, and only the differences from the respective embodiments are described. Although the description and the drawings are directed to electron optical devices, it should be understood that the embodiments are not used to limit the present disclosure to specific charged particles. Therefore, throughout this document, references to items mentioned with respect to electrons and reference electrons can be more generally considered as references to charged particles, and references to items mentioned with respect to reference charged particles, where the charged particles are not necessarily electrons.

[0029] Now refer to Figure 1 , Figure 1 which is a schematic diagram illustrating an exemplary evaluation device 100 or inspection device. Figure 1 The evaluation device 100 of

[0030] The EFEM 30 includes a first load port 30a and a second load port 30b. The EFEM 30 may include additional load port(s). The first load port 30a and the second load port 30b may receive, for example, a front-opening unified pod (FOUP) that houses a substrate (e.g., a semiconductor substrate or a substrate made of other material(s)) or a target to be evaluated (substrates, wafers, and samples are hereinafter collectively referred to as "targets"). One or more robotic arms (not shown) in the EFEM 30 transport the target to the load lock chamber 20.

[0031] The load lock chamber 20 is used to remove the gas around the target. The load lock chamber 20 may be connected to a load lock vacuum pump system (not shown) that removes gas particles in the load lock chamber 20. The operation of the load lock vacuum pump system enables the load lock chamber to reach a first pressure below atmospheric pressure. The main chamber 10 is connected to a main chamber vacuum pump system (not shown). The main chamber vacuum pump system removes gas molecules in the main chamber 10 so that the pressure around the target reaches a second pressure lower than the first pressure. After reaching the second pressure, the target is transported to the charged particle optical device 40 through which the target can be evaluated. The charged particle optical device 40 may include a single-beam or multi-beam charged particle optical apparatus.

[0032] The controller 50 is electrically connected to the charged particle optical device 40. The controller 50 may be a processor (such as a computer) configured to control the charged particle beam evaluation device 100. The controller 50 may also include processing circuitry configured to perform various signal and image processing functions. Although the controller 50 is Figure 1 shown as being located outside the structure including the main chamber 10, the load lock chamber 20, and the EFEM 30, it should be understood that the controller 50 may be part of the structure. The controller 50 may be located in one of the constituent elements of the charged particle beam evaluation device or may be distributed over at least two of the constituent elements. Although the present disclosure provides an example of the main chamber 10 that houses the electron beam evaluation device, it should be noted that aspects of the present disclosure are not limited in the broadest sense to a chamber that houses the charged particle optical device. Instead, it should be understood that the above principles may also be applied to other devices and other device arrangements operating at the second pressure.

[0033] Now referring to Figure 2 , Figure 2 is an evaluation device (e.g., Figure 1Schematic diagram of an exemplary multi-beam charged particle optical device 40 of the evaluation apparatus 100). In an alternative embodiment, the evaluation apparatus 100 is a single-beam evaluation apparatus. The charged particle optical device 40 may include an electron source 201, a beam former array 372 (also referred to as a gun aperture plate, Coulomb aperture array, or pre-sub-beam-forming aperture array), a condenser lens 310, a source converter (or micro-optical array) 320, an objective lens 331, and a target 308. In one embodiment, the condenser lens 310 is magnetic. The target 308 may be supported by a support on a stage. The stage may be motorized. The stage moves such that the target 308 is scanned by incident electrons. The electron source 201, the beam former array 372, and the condenser lens 310 may be components of an illumination device composed of the charged particle optical device 40. The source converter 320 (also referred to as a source conversion unit), which is described in more detail below, and the objective lens 331 may be components of a projection device composed of the charged particle optical device 40.

[0034] The electron source 201, the beam former array 372, the condenser lens 310, the source converter 320, and the objective lens 331 are aligned with the main electron optical axis 304 of the charged particle optical device 40. The electron source 201 may generate a main beam 302 that generally travels along the electron optical axis 304 and has a source crossover (virtual or real) 301S. During operation, the electron source 201 is configured to emit electrons. The electrons are extracted or accelerated by an extractor and / or an anode to form a primary beam 302.

[0035] The beam former array 372 cuts the peripheral electrons of the primary electron beam 302 to reduce the resulting Coulomb effect. The primary electron beam 302 may be trimmed by the beam former array 372 into a specified number of sub-beams, such as three sub-beams 311, 312, and 313. It should be understood that this description is intended to apply to charged particle optical devices 40 having any number of sub-beams (e.g., one, two, or more than three). In operation, the beam former array 372 is configured to block the peripheral electrons to reduce the Coulomb effect.

[0036] The source converter 320 is configured to convert the beam (including sub-beams, if any) transmitted by the beam former array 372 into sub-beams projected towards the target 308. In one embodiment, the source electrode converter is a unit. Alternatively, the term source converter may simply be used as a collective term for a group of components that form a beam wave from sub-beams.

[0037] As Figure 2As shown, in one embodiment, the charged particle optical device 40 includes a beam limiting aperture array 321 having an aperture pattern (i.e., apertures arranged in a formation) configured to define the outer dimensions of a beam wave (or sub - beam) projected towards the target 308. In one embodiment, the beam limiting aperture array 321 is part of the source converter 320. In an alternative embodiment, the beam limiting aperture array 321 is part of a system upstream (upbeam) of the beam in the main device. In one embodiment, the beam limiting aperture array 321 divides one or more sub - beams 311, 312, 313 into beam waves such that the number of beam waves projected towards the target 308 is greater than the number of sub - beams transmitted through the beam former array 372. In an alternative embodiment, the beam limiting aperture array 321 maintains the number of sub - beams incident on the beam limiting aperture array 321, in which case the number of sub - beams may be equal to the number of beam waves projected towards the target 308.

[0038] As Figure 2 As shown, in one embodiment, the charged particle optical device 40 includes a pre - bending deflector array 323 having pre - bending deflectors 323_1, 323_2, and 323_3 for bending the sub - beams 311, 312, and 313, respectively. The pre - bending deflectors 323_1, 323_2, and 323_3 may bend the paths of the sub - beams 311, 312, and 313 onto the beam limiting aperture array 321.

[0039] The charged particle optical device 40 may also include an image forming element array 322 having image forming deflectors 322_1, 322_2, and 322_3. There are corresponding deflectors 322_1, 322_2, and 322_3 associated with the paths of each beam wave. The deflectors 322_1, 322_2, and 322_3 are configured to deflect the paths of the beam waves towards the electron optical axis 304. The deflected beam waves form virtual images (not shown) of the source intersection point 301S. In the current embodiment, these virtual images are projected onto the target 308 by the objective lens 331, and detection points 391, 392, and 393 are formed thereon. The charged particle optical device 40 may also include an aberration compensator array 324 configured to compensate for aberrations that may be present in each sub-beam. In one embodiment, the aberration compensator array 324 includes lenses configured to operate on the corresponding beam waves. The lenses may take the form of an array of lenses. The lenses in the array may operate on different beam waves of multiple beams. The aberration compensator array 324 may include, for example, a field curvature compensator array (not shown) having microlenses. For example, the field curvature compensator and the microlenses may be configured to compensate for field curvature aberrations apparent at the detection points 391, 392, and 393 of the individual sub-beams. The aberration compensator array 324 may include an astigmatism compensator array (not shown) having micro-stigmators. For example, the micro-stigmators may be controlled to operate on the sub-beams to compensate for astigmatism aberrations present at the detection points 391, 392, and 393.

[0040] The image forming element array 322, the aberration compensator array 324, and the pre-bending deflector array 323 may include multi-layer sub-beam manipulation devices, some of which may be in the form of arrays, such as: micro-deflectors, microlenses, or micro-stigmators. The beam paths may be rotationally manipulated. Rotation correction may be applied by magnetic lenses. Rotation correction may alternatively or additionally be achieved by existing magnetic lenses, such as condenser lens arrangements.

[0041] The objective lens 331 focuses the beam waves onto the surface of the target 308, i.e., it projects three virtual images onto the target surface. The three images formed by the three sub-beams 311 to 313 on the target surface form three detection points 391, 392, and 393 thereon. In one embodiment, the deflection angles of the sub-beams 311 to 313 are adjusted to pass through or near the front focal point of the objective lens 331 to reduce or limit off-axis aberrations of the three detection points 391 to 393. In one arrangement, the objective lens 331 is magnetic. Although three beam waves are mentioned, this is only an example. There may be any number of beam waves.

[0042] In one embodiment, a beam separator (not shown) is provided. The beam separator can be downstream of the beam of the source converter 320 (downbeam). The beam separator can be, for example, a Wien filter including an electrostatic dipole field and a magnetic dipole field. The beam separator can be upstream of the beam of the objective 331. In operation, the beam separator can be configured to apply an electrostatic force to the individual electrons of the sub-beam through the electrostatic dipole field. In one embodiment, the magnitude of the electrostatic force is equal to, but opposite in direction to, the magnetic force applied to the individual primary electrons of the sub-beam by the magnetic dipole field of the beam separator. Thus, the sub-beam can pass through the beam separator at least substantially straight with a deflection angle of at least substantially zero. The direction of the magnetic force depends on the direction of electron movement, while the direction of the electrostatic force does not depend on the direction of electron movement. Thus, since secondary electrons and backscattered electrons (or signal electrons) typically move in a direction opposite to that of the primary electrons, the magnetic force applied to the secondary electrons and backscattered electrons (or signal particles) will no longer be able to cancel out the electrostatic force, and thus the secondary electrons and backscattered electrons passing through the beam separator will deviate from the electron optical axis 304.

[0043] In one embodiment, a secondary device (not shown) is provided that includes detection elements for detecting a corresponding secondary charged particle beam. When the secondary beam is incident on the detection elements, these elements can generate a corresponding intensity signal output. The output can be directed to an image processing system (e.g., controller 50). Each detection element can include an array, which can be in the form of a grid. The array can have one or more pixels; each pixel can correspond to an element of the array. The intensity signal output of the detection element can be the sum of the signals generated by all the pixels within the detection element.

[0044] In one embodiment, a secondary projection device and its associated electron detection device (not shown) are provided. The secondary projection device and its associated electron detection device can be aligned with the secondary electron optical axis of the secondary device. In one embodiment, the beam separator is arranged to deflect the path of the secondary electron beam towards the secondary projection device. The secondary projection device then focuses the path of the secondary electron beam onto a plurality of detection regions of the electron detection device. The secondary projection device and its associated electron detection device can use secondary electrons or backscattered electrons (or signal particles) to record and generate an image of the target 308.

[0045] Such a Wien filter, secondary device, and / or secondary projection device may be provided in a single beam evaluation device. Additionally and / or alternatively, a detection device may be present downstream of the beam of the objective lens, e.g., facing the sample during operation. In an alternative arrangement, the detector device is positioned along the path of the charged particle beam towards the sample. Such an arrangement does not have a Wien filter, secondary device, and secondary projection device. The detection device may be positioned at one or more locations along the path of the charged particle beam towards the sample, such as facing the sample during operation, e.g., around the path of the charged particle beam. Such a detector device may have holes and may be annular. Different detector devices may be positioned along the path of the charged particles to detect signal particles having different characteristics. Electro-optical elements along the path of the charged particle beam (which may include one or more electrostatic plates having holes for the path of the charged particle beam) may be arranged and controlled to focus signal particles having correspondingly different characteristics to respective detector devices at different locations along the path of the charged particle beam. Such electrostatic plates may be arranged in series by two or more adjacent plates along the path of the charged particle beam.

[0046] Any element or collection of elements within the charged particle optical device is replaceable or field replaceable. One or more electro-optical components in the charged particle optical device, particularly those that operate on or generate sub-beams (such as hole arrays and manipulator arrays), may include one or more plates and each plate may be an electrode, or may include one or more electrodes for each hole of the array. Such plates may be fabricated using processes suitable for manufacturing microelectromechanical systems (MEMS); such charged particle optical components or devices may be referred to as MEMS. MEMS are miniaturized mechanical and electromechanical elements fabricated using microfabrication techniques. The pre-bent deflector array 323 may be a MEMS. In one embodiment, the charged particle optical device 40 includes holes, lenses, and deflectors that may be formed as MEMS. In one embodiment, such as lenses and deflectors 322_1, 322_2, and 322_3, etc., are controllable passively, actively, as an entire array, individually, or in groups within the array to control the beam wave of the charged particles projected towards the target 308.

[0047] In one embodiment, the charged particle optical device 40 may include alternative and / or additional components on the charged particle path, such as lenses and other components, some of which have been described previously with reference to Figure 1 and Figure 2 which. Examples of such an arrangement are shown in Figure 3 and Figure 4 wherein, Figure 3 and Figure 4This will be described in more detail later. A detector is provided to detect charged particles emitted by a sample. The detector may be integrated into the objective lens. The detector may be located on the bottom surface of the objective lens so as to face the sample in use. The detector may include, for example, an array of detector elements, which may correspond to an array of beam waves of a multi-beam arrangement. The detectors (or detector elements) in the detector array may generate detection signals associated with the pixels of the generated image. The condenser lens, the objective lens, and / or the detector may be formed as MEMS or CMOS devices.

[0048] Figure 3 FIG. 4 is a schematic diagram of another design of an exemplary charged particle optical device 40. The charged particle optical device 40 may include a source 201 and one or more electron optical components. Alternatively, the electron optical apparatus including the charged particle optical device 40 may include the source 201. The charged particle optical device 40 may include an upper beam limiter 252, an array of collimator elements 271, an array of control lenses 250, an array of scanning deflectors 260, an array of objective lenses 241, a beam shaping limiter 242, and a detector array. The source 201 provides a beam of charged particles (e.g., electrons).

[0049] The upper beam limiter 252 defines an array of beam limiting holes. The upper beam limiter 252 may be referred to as an upper beam limiting hole array or an upstream beam limiting hole array of the beam. The upper beam limiter 252 may include a plate having a plurality of holes (which may be a plate-like body). The upper beam limiter 252 forms sub-beams from the charged particle beam emitted by the source 201. The other parts of the beam except for the parts contributing to the formation of the sub-beams may be blocked (e.g., absorbed) by the upper beam limiter 252 so as not to interfere with the sub-beams downstream of the beam. The upper beam limiter 252 may be referred to as a sub-beam defining hole array.

[0050] The array of collimator elements 271 is provided downstream of the beam of the upper beam limiter 252. Each collimator element collimates the corresponding sub-beam. The array of collimator elements 271 may be formed using MEMS manufacturing techniques for spatial compactness. In some embodiments, as Figure 3 illustrated in FIG. 4, the array of collimator elements 271 is the first deflector or focusing electron optical array element in the beam path downstream of the beam of the source 201. In another arrangement, the collimator may be in the form of a macro-collimator in whole or in part. Such a macro-collimator may be upstream of the beam of the upper beam limiter 252, so it operates on the beam from the source before the generation of the multi-beams. A magnetic lens may be used as the macro-collimator.

[0051] Downstream of the beam of the collimator element array, there is a control lens array 250. The control lens array 250 includes a plurality of control lenses. Each control lens includes at least two electrodes (e.g., two or three electrodes) connected to corresponding potential sources. The control lens array 250 may include an array of two or more (e.g., three) plate electrodes connected to corresponding potential sources. The control lens array 250 is associated with the objective lens array 241 (e.g., the two arrays are close to each other and / or mechanically connected to each other and / or controlled together as a unit).

[0052] As described above, the control lens array 250 is associated with the objective lens array 241. As described above, the control lens array 250 can be regarded as providing additional electrodes in addition to the electrodes 242, 243 of the objective lens array 241, for example, as part of the objective lens array component. The additional electrodes of the control lens array 250 achieve more degrees of freedom for controlling the electron optical parameters of the sub-beams. In one embodiment, the control lens array 250 can be regarded as an additional electrode of the objective lens array 241, thereby realizing an additional function of the corresponding objective lens of the objective lens array 241. In one arrangement, such an electrode can be regarded as part of the objective lens array, which provides an additional function for the objective lenses of the objective lens array 241. In this arrangement, even though the control lens is only referred to as part of the objective lens, for example, in terms of providing an additional degree of freedom for the objective lens, the control lens is considered to be part of the corresponding objective lens. Although the control lens array 241 may not be different from and is part of the objective lens array 250, in this specification, the control lens array 250 is considered to be different from and separate from the objective lens array 241.

[0053] For ease of illustration, the lens array is schematically depicted here as an elliptical array. Each ellipse represents a lens in the lens array. By convention, ellipses are used to represent lenses, similar to the biconvex shape often employed in optical lenses. However, in the context of charged particle arrangements such as those discussed herein, it can be understood that the lens array will typically operate electrostatically and thus may not require any physical elements having a biconvex shape. As described above, the lens array may instead include a plurality of plates having holes.

[0054] A scan deflector array 260 including a plurality of scan deflectors may be provided. The scan deflector array 260 can be formed using MEMS manufacturing techniques. Each scan deflector scans a corresponding sub-beam on the sample 208. In one embodiment, the scan deflectors described in EP2425444 can be used to implement the scan deflector array 260, the entire content of which is incorporated herein by reference, specifically regarding scan deflectors.

[0055] An objective lens array 241 including a plurality of objective lenses is provided to direct sub-beams onto a sample 208. Each objective lens includes at least two electrodes (e.g., two or three electrodes) connected to respective potential sources.

[0056] The objective lens array can form part of an objective lens array component together with any one or all of a scanning deflector array 260, a control lens array 250, and a collimator element array 271. The objective lens array component may also include a beam shaping limiter 242. The beam shaping limiter 242 defines an array of beam limiting apertures. The beam shaping limiter 242 may be referred to as a lower beam limiter, a lower beam limiting aperture array, or a final beam limiting aperture array.

[0057] In one arrangement, the beam shaping limiter 242 is structurally integrated with the electrodes 302 of the objective lens array 241. Desirably, the beam shaping limiter 242 is located in a region with a low electrostatic field strength. Each beam limiting aperture is aligned with a corresponding objective lens in the objective lens array 241.

[0058] In one embodiment, the charged particle optical device 40 is configured to control the objective lens array component (e.g., by controlling the potential applied to the electrodes of the control lens array 250) such that the focal length of the control lens is greater than the spacing between the control lens array 250 and the objective lens array 241. Thus, the control lens array 250 and the objective lens array 241 can be positioned relatively close together, where the focusing action from the control lens array 250 is too weak to form an intermediate focus between the control lens array 250 and the objective lens array 241. The control lens array and the objective lens array operate together to define a combined focal length to the same surface. The combined operation without an intermediate focus can reduce the risk of distortion. In other embodiments, the objective lens array component can be configured to form an intermediate focus between the control lens array 250 and the objective lens array 241.

[0059] A power supply can be provided to apply respective potentials to the control lenses of the control lens array 250 and the electrodes of the objective lenses of the objective lens array 241.

[0060] A detector array (not shown) is provided to detect charged particles emitted from sample 208. The detected charged particles can include any charged particles (e.g., signal particles) detected by a scanning electron microscope, including secondary (e.g., emitted) and / or backscattered electrons from sample 208. The detector can be an array that provides a surface of a charged particle optical device facing sample 208, such as the bottom surface of the charged particle optical device. Alternatively (or additionally), the detector array is upstream of the beam at the bottom surface, or for example in or upstream of an objective lens array or a control lens array. Elements of the detector array can correspond to beam waves of a multi-beam arrangement. Signals generated by the detection of electrons by the elements of the array can be transmitted to a processor for image generation. The signal can correspond to a pixel of the image.

[0061] In other embodiments, both a macro scan deflector and a scan deflector array 260 are provided. In such an arrangement, scanning of the sub-beams over the sample surface can be achieved by jointly, preferably synchronously controlling the macro scan deflector and the scan deflector array 260.

[0062] In one embodiment, as Figure 4 illustrated, an array 500 of charged particle optical devices is provided. Array 500 can include a plurality of any of the charged particle optical devices described herein. Each charged particle optical device simultaneously focuses a corresponding multi-beam onto different regions of the same sample.

[0063] Any number of charged particle optical devices can be used in array 500. Each charged particle optical device in array 500 can be configured in any of the ways described herein, such as as described above, particularly with reference to Figure 3 the embodiments shown and described. Details of such an arrangement are described in EPA 20184161.6 filed on July 6, 2020, regarding how the objective lens is incorporated and applicable to a multi-device arrangement, which is hereby incorporated by reference herein.

[0064] In Figure 4 the example of, array 500 includes a plurality of charged particle optical devices of the type described above with reference to Figure 3 those described.

[0065] In addition to those described and Figure 5 shown below, alternative designs of multi-beam charged particle optical devices can have the same features as Figure 3 those described. Alternative designs of multi-beam charged particle optical devices can include a condenser lens array 231 upstream of the beam of an objective lens array arrangement 241, as disclosed in EP application 20158804.3 filed on February 21, 2020, which is incorporated by reference herein to describe a multi-beam device with a collimator and its components.

[0066] In an embodiment of the arrangement shown and described in the reference Figure 5 the detector may be located in a similar position in the charged particle optical device 40 as shown and described in the charged particle optical device of the reference Figure 3 The detector 240 may be integrated into the objective lens array 241 and the control lens array 250 (when present as not shown in Figure 5 ). The detector may have more than one detector at different positions along the path of the sub-beams of the multi-beam.

[0067] As shown in the reference Figure 4 the charged particle optical device array may have a plurality of multi-beam devices of this design as shown in Figure 3 the multi-beam device. The plurality of multi-beam devices may be arranged in a multi-beam device array. Such an arrangement is shown and described in EP application 20158732.6 filed on February 21, 2020, which is incorporated herein by reference and relates to a multi-device arrangement of a multi-beam device having the disclosed multi-beam device design having a collimator at or even near the intermediate focus. Another alternative design of the multi-beam device includes a plurality of single-beam devices.

[0068] As Figure 6 shown, in one embodiment, the charged particle optical device 40 includes a beam tube 300 (which may also be referred to as a tube, liner or boost tube). In one embodiment, the beam tube 300 is arranged to surround the multi-beam path. The beam tube 300 surrounds the path of the charged particles. The charged particles may be a source beam emitted from the source 121 towards the sample. The charged particles may be the plurality of beams in the multi-beam. For example, when viewed along the main axis of the charged particle optical device 40, i.e., in the direction of the charged particle beam, the beam tube 300 may surround the source beam path or the multi-beam path. In one embodiment, the beam tube 300 is configured to surround only a part of the charged particle path, i.e., a part of the charged particle path along the length of the charged particle path, for example, along a part of the length of the charged particle path. For example, as Figure 6 shown, in one embodiment, the beam tube 300 surrounds a part of the multi-beam path from the source 201 to directly above the sub-beam forming array 252. In other embodiments, the beam tube 300 surrounds different parts of the multi-beam path, such as the length.

[0069] In one embodiment, the beam tube 300 is configured to operate at a first potential difference relative to ground. The support may be configured to support the sample 208 at a second potential difference relative to ground or at ground potential. The first potential difference may be greater than the second potential difference, and thus cause a plurality of beams of charged particles to be accelerated towards the sample 208. Arranging the potential difference between the sample and the immediate environment to be relatively low can reduce the likelihood of electrical breakdown occurring near the sample 208. This can reduce the likelihood of the sample 208 being damaged. The risk of damaging components of the charged particle device 41, such as the detector 240 (which may have delicate electronic components), can be reduced.

[0070] As described above, as Figure 6 illustrated, the electron source 201 may include a cathode 121 and an anode 122 (which may also be referred to as an extractor or extractor electrode). The cathode 121 and the anode 122 are configured to operate at a potential difference therebetween. The cathode 121 is configured to emit a beam of charged particles. The anode 122 is configured to accelerate the beam of charged particles towards the sample 208. Note that this source arrangement is a simplified arrangement. The source 201 may have different arrangements and other electrodes, as long as the source 201 has a most downstream source electrode, herein referred to as the anode 122.

[0071] As Figure 6 shown, in one embodiment, the beam tube 300 is electrically connected to the anode 122. By electrically connecting the beam tube 300 to the anode 122, no electric field is formed between the source 201 and the beam tube 300. Any undesirable lensing effects upstream of the beam in the beam tube 300 are avoided. The beam tube 300 may be formed together with the anode 122. The beam tube 300 and the anode 122 may be integral. Alternatively, the beam tube 300 may be separated from the source 201. The beam tube 300 may be axially spaced apart from the anode 122 by a certain distance.

[0072] As Figure 6 shown, in one embodiment, at least a portion of the charged particle device 41 is downstream of the beam at the most downstream end of the beam tube 300. For example, the sub-beam forming array 252, the control lens array 250, the objective lens array 241, and the beam shaping aperture array 262 may be provided downstream of the beam in the beam tube 300. In one embodiment, a portion of the charged particle device 41 downstream of the beam in the beam tube 300 may be configured to decelerate the beam of charged particles. A portion of the charged particle device 41 downstream of the beam in the beam tube 300 may be referred to as charged particle optics.

[0073] In one embodiment, the charged particle optical device 40 is configured such that a charged particle beam passes through the charged particle optical device 40 without imposing an undesired lensing effect on the beam. The beam downstream end of the beam tube 300 may be configured to be located in a region with a small electric field or no electric field. This can help reduce or avoid any lensing effect on the charged particle beam that may be caused by an electric field between the beam tube 300 and any part of the charged particle device 41 downstream of the beam in the beam tube 300. In a different arrangement that may be less desirable, a controlled potential difference may exist between the beam downstream end of the beam tube 300 and the surface of an adjacent part of the charged particle optical device 41 for lensing the path of the charged particles towards the sample 208.

[0074] As Figure 6 shown, in one embodiment, the beam tube 300 is spaced apart from a part of the charged particle device 41 downstream of the beam in the beam tube 300. The spacing can make it easier to manufacture the charged particle device (by relaxing tolerances) and / or replace parts or all of the charged particle device 41. In one embodiment, the separation is at most 1 mm. Any electric field between the beam tube 300 and any part of the charged particle device 41 downstream of the beam in the beam tube 300 can be restricted to a small distance. This arrangement can help reduce or even prevent the influence of any electric field between the beam tube 300 and the part of the charged particle device downstream of the beam in the beam tube 300. In an alternative arrangement, the spacing between the beam tube 300 and the surface of the charged particle device 41 downstream of the beam in the beam tube 300 can enable a lensing operation on the charged particles projected towards the sample position.

[0075] In an alternative embodiment, the beam tube 300 is electrically connected to a part of the charged particle device 41 downstream of the beam in the beam tube 300. For example, the beam tube 300 may be structurally connected to an associated plate (e.g., the sub-beam forming array 252) and / or be integral with it.

[0076] In Figure 6 an example, a macro collimator 270 including magnetic components is provided, for example as part of the charged particle device 41. While being located outside the beam tube 300, the magnetic components can affect the trajectory of the charged particles within the beam tube 300.

[0077] In an alternative embodiment, the macro collimator 270 includes electrostatic components. Such electrostatic components can be affected by the beam tube 300, such as its shielding of the electrostatic field outside the beam tube 300. In one embodiment, the electrostatic components of the macro collimator 270 are located inside the beam tube 300 (not shown) or between the lengths or sections of the beam tube (see EP application 21199203.7 filed on September 27, 2021, which is incorporated herein by reference at least in terms of the design including the electron optical elements and the beam tube and its sections).

[0078] In one embodiment, the charged particle device 41 includes a macro scan deflector 265. The macro scan deflector 265 is configured to deflect corresponding portions of the charged particle beam. The corresponding portions correspond to different sub-beams further downstream in the beam. Thus, the deflection of each portion by the macro scan deflector 265 causes the corresponding sub-beams of charged particles to be scanned in the multi-beam to be deflected relative to the sample 208 (e.g., thereon). As Figure 6 shown, in one embodiment, the macro scan deflector 265 is upstream of the beam at the downstream end of the beam tube 300.

[0079] As Figure 6 shown, in one embodiment, the macro scan deflector 265 includes a magnetic deflector. The macro scan deflector 265 may be located outside the beam tube 300.

[0080] In an alternative embodiment, the macro scan deflector is electrostatic. Such an electrostatic scan deflector may be placed between sections or lengths of the beam tube 300. The electrostatic scan deflector may be spaced apart from the sections of the beam tube 300 both upstream and downstream of the beam in the scan deflector 300.

[0081] Additionally or alternatively, a scan deflector including a deflector array may be provided in place of the macro scan deflector. As Figure 3 shown, such a deflector array is provided as an array of scan deflectors 260 within the charged particle device 41. Such a scan deflector array may be associated with an objective lens array, e.g., where the deflectors of the array are associated with each beam of the multi-beam.

[0082] In Figure 6 the embodiment shown, the beam tube 300 extends continuously from a position near the sub-beam forming array 252 to the source 122. When the beam tube 300 is metallic (or coated with a metallic material), this will shield the interior of the beam tube 300 from electrostatic fields generated outside the beam tube 300. As described above, elements may be provided to manipulate the charged particle trajectories within the beam tube 300, which may be achieved either via a magnetic field generated outside the beam tube 300 or via a magnetic or electrostatic field generated within the beam tube 300. Another possibility (not shown) is to provide a gap in the beam tube 300 to allow an electric field generated outside the beam tube to affect the charged particle trajectories within the beam tube 300.

[0083] The charged particle optical device 40 may be a component of an evaluation device (e.g., for inspection, metrology, subway inspection, or any other type of evaluation), or may be part of an electron beam lithography device or other type of charged particle-induced sample patterning device. The multi-beam charged particle device may be used for many different applications, including general electron microscopy, and not just scanning electron microscopy and lithography.

[0084] As described in the introductory part of the specification, a high electric field can trigger a discharge event through electrical breakdown, which may lead to component damage. For example, in the case where a detector array is positioned adjacent to a sample 208 and held at different electric potentials, a high electric field can exist between the detector array and the sample 208. A potential difference may be required to improve the collection efficiency of the detector array for signal particles. A close spacing between the detector array and the sample 208 may be required to prevent excessive crosstalk between different detector elements of the detector array. Discharge events caused by the high electric field generated in the region between such a detector array and the sample 208 may damage sensitive elements of the detector array, such as sensitive components within the integrated circuit forming the detector array or associated with the operation of the detector array. The discharge event can alternatively or additionally be triggered by an electric field upstream of the beam of the detector array. The discharge event can be generated in other parts of the charged particle device 40 and may alternatively or additionally cause damage to components located elsewhere within the charged particle device 40.

[0085] In one embodiment, the risk of discharge damage can be reduced by using a discharge damage protection element (or discharge protection element), such as a diode, a clamp circuit, or a transistor (e.g., CMOS, bipolar, and IGBT). However, such discharge damage protection increases system complexity and / or reduces noise performance (e.g., reduces the ratio of the detection signal to noise). For example, the inventors have found that the capacitance of a discharge protection element (such as a diode) used to provide discharge damage protection has an adverse effect on the noise performance; for example, it increases the difficulty of differentiating the detection signal and noise for a meaningful evaluation of the sample, so discharge damage protection is not desirable in a detector array.

[0086] The embodiments specifically described below are intended to address at least one or more of these problems. In some of these embodiments, discharge damage protection is provided by configuring the electrical environment of sensitive circuitry (e.g., on-chip circuitry associated with a detector array) such that even in the presence of a discharge event, the voltage across the sensitive element and the current through the sensitive element do not exceed a critical value. This can be achieved by providing a low-impedance connection at a stable electric potential and between sensitive elements (e.g., a detector array). Some of the embodiments described below achieve this by connecting the sensitive element to the ground potential using a low-impedance connection.

[0087] In one embodiment, a charged particle device is provided for projecting multiple beams of charged particles onto a sample 208. The charged particle device includes a sample support for supporting the sample 208. The sample support may include a motorized or actuated stage, and / or take the form as referred to above Figure 1 and / or Figure 2Any of the forms described. In one embodiment, the charged particle device includes a charged particle optical device 40. The charged particle optical device 40 is configured to project multiple beams of charged particles towards the sample 208 along multiple paths. The charged particle optical device 40 includes a plurality of charged particle optical elements 60 that define lenses such as an objective lens and / or a control lens, in which a plurality of apertures are defined along the path of the beam. The charged particle optical elements 60 can be planar elements that are substantially orthogonal to the path of the beam.

[0088] In one embodiment, as Figure 7 illustrated, the plurality of charged particle optical elements 60 are disposed in the charged particle optical module 55. In Figure 7 the orientation shown, the multiple paths can have directions corresponding to the charged particle optical axis of the charged particle optical device 40. In the depicted orientation, the multiple paths can be substantially perpendicular in the plane of the page; however, this orientation is convenient for this description. The orientation of the charged particle optical module 55 can be any orientation that is desirably selected. The apertures are disposed in the beam region 62 of the charged particle optical elements 60. As Figure 7 shown, when viewed in a direction parallel to the path of the beam and / or perpendicular to the plane of the charged particle optical element, the beam regions 62 can be located substantially centrally and / or aligned with each other. The lens can be an objective lens array 241 and / or a control lens array 250. The plurality of charged particle optical elements 60 can additionally or alternatively define a condenser lens array 231 and / or a collimator array 271 and / or individual beam correctors and / or deflectors and / or a Wien filter array. The charged particle optical device 40 can take any of the forms described above with reference to Figures 1 - 6 or other forms.

[0089] As Figure 7 shown, in one embodiment, the charged particle optical module 55 includes one or more spacers 70 - 72. The spacers 70 - 72 are configured to mechanically support the charged particle optical elements 60. Some or all of the spacers 70 - 72 can be configured to electrically isolate at least a subset of the charged particle optical elements 60 from each other.

[0090] In one embodiment, the charged particle optical module 55 is field replaceable. The charged particle optical module 55 can be removed from and / or inserted into the charged particle optical device 40 without any substantial disassembly of other parts of the charged particle optical device 40. That is, the charged particle optical module 55 can be removed from and / or inserted into the charged particle optical device 40.

[0091] In one embodiment, at least two charged particle optical elements 60 are configured to be disposed at different electric potentials. In one embodiment, at least one charged particle optical element 60 is disposed at ground electric potential. In some embodiments, at least one charged particle optical element disposed at ground electric potential includes an electrode of an objective lens. Alternatively or additionally, at least one charged particle optical element disposed at ground electric potential includes a detector substrate that includes a detector array configured to detect signal particles emitted from a sample 208. As described in further detail below, the detector array may include an array of detector elements and / or an integrated circuit in the detector substrate. The detector array may take any form specifically referred to above Figures 3 - 5 in the foregoing. The detector array may form part of a detector 240.

[0092] Disposing at least one charged particle optical element 60 at ground electric potential helps to provide a low impedance circuit from the charged particle optical element 60 to a stable electric potential. This can reduce the risk of damage to the charged particle optical element 60 due to a discharge event. Alternatively or additionally, disposing at least one charged particle optical element 60 at ground electric potential can provide electrostatic shielding, thereby reducing the risk of damage to a fragile component, such as a detector array, by an electric field on the opposite side of the shielding.

[0093] In one embodiment, at least two charged particle optical elements 60 are configured to face each other. In one embodiment, one of the at least two charged particle optical elements 60 configured to face each other is a facing electrode 60B. The facing electrode 60B may be an electrode of an objective lens. The facing electrode 60B defines a continuous conductive surface that is configured to define a plurality of holes in the facing electrode 60B. Each hole may surround a path of a respective beam of a plurality of beams. The continuous conductive surface electrostatically shields a charged particle optical element 60A (which may be referred to as a shielded charged particle optical element 60A) that the facing electrode 60B faces. The shielded charged particle optical element 60A is shielded from an electric field on the opposite side of the facing electrode 60B. Thus, the shielded charged particle optical element 60A can be shielded from an electric field upstream of the beam in the facing electrode 60B. Shielding the shielded charged particle optical element 60A from the electric field can reduce or prevent the risk of damage to the shielded charged particle optical element 60A due to the electric field. The facing electrode 60B may be disposed at ground electric potential.

[0094] In one embodiment, the charged particle device includes a first spacer element 71. The first spacer element 71 may be electrically connected to at least one charged particle optical element in the charged particle optical element 60. In one embodiment, the first spacer element 71 is electrically connected to at least the shielded charged particle optical element 60A. In one embodiment, the first spacer element 71 is set to ground potential. Accordingly, the electrical connection from the first spacer element 71 to the shielded charged particle optical element 60A may set the shielded charged particle optical element 60A to ground potential.

[0095] In one embodiment, the shielded charged particle optical element 60A is connected to the facing electrode 60B via the first spacer element 71. In one embodiment, the first spacer element 71 defines at least one conductive body having a planar shape. The first spacer element 71 may be referred to as a conductive spacer. An example shape of the first spacer element 71 is depicted in Figure 8 FIG. Figure 8 is a cross-sectional view of the first spacer element 71 of the charged particle optical module 55 taken along an axis parallel to the path of the beams of the multi-beam, as viewed through Figure 7 FIG. Figure 7 FIG. Figure 7 FIG. Figure 7 In the example of FIG.

[0096] Figure 9 FIG. Figure 7 FIG. Figure 9 FIG. Figure 9In the example of, the conductive layers 71B, 71C are disposed on both sides of the first spacer element 71. Each of the conductive layers 71B, 71C may include, for example, a metal layer. In one embodiment, the conductive layers 71B, 71C include chromium. In one embodiment, at least one conductive body includes a doped semiconductor 71A (e.g., a body including doped silicon). In addition to or in place of the conductive coatings or conductive layers 71B, 71C, a doped semiconductor 71A may be provided. Doping of the semiconductor can provide charge carriers that can enhance conductivity.

[0097] In one embodiment, as Figure 9 illustrated in, the first spacer element 71 contacts the facing electrode 60B on a peripheral minor surface (e.g., a radially outward surface) of the facing electrode 60B that faces the electrode. Alternatively or additionally, the first spacer element 71 may contact a main surface of the facing electrode 60B on a side of the facing electrode 60B that is closest to the sample 208 (e.g., a side that faces downward in the orientation of Figure 9 . Alternatively, the first spacer element 71 may be spaced apart from the facing electrode 60B. Since the module 55 is in a vacuum, a vacuum may exist between the facing electrode 60B and the shielded electron optical element 60A and between the facing electrode 60B and the first spacer element 71. This may be desirable to thermally isolate the first spacer element 71 from the facing electrode 60B. The vacuum can act as a thermal insulator. Thermally isolating the first spacer element 71 from the facing electrode 60B can reduce heat flow between the facing electrode 60B and elements that are in thermal contact with the first spacer element 71, such as the shielded electron optical element 60A. This may be desirable in cases where the shielded electron optical element 60A generates heat during use and is used to prevent that heat from causing an excessive increase in the temperature of the facing electrode 60B. In one embodiment, the first spacer element 71 is configured to define a hole. When viewed perpendicular to the plane of the facing electrode 60B, e.g., when viewed from the shielded electron optical element 60A in the upstream direction of the beam, the hole may be large enough such that all of the facing electrodes 60B are within the hole, where there is a gap around the facing electrodes 60B in most or all lateral directions. The hole may have a size that is larger than the size of the facing electrode 60B (e.g., in-plane width, length, or diameter), such as a corresponding size of the facing electrode 60B, e.g., in a direction across (e.g., perpendicular to) the path of the beam of multiple beams. The hole may have an area that is larger than the cross-sectional area of the facing electrode 60B.

[0098] In one embodiment, as Figure 9As illustrated, the charged particle device further includes a second spacer element 72. The second spacer element 72 may be configured to support the facing electrode 60B. Alternatively or additionally, the second spacer element 72 may be configured to electrically isolate the facing electrode 60B from other components of the charged particle device, such as other charged particle optical elements. In one embodiment, the facing electrode 60B is mechanically connected to an upstream electrode upstream of the beam of the facing electrode 60B via the second spacer element 72. The second spacer element 72 may be configured to electrically isolate the facing electrode 60B from the upstream electrode of the beam. Thus, the second spacer element 72 may include at least a low-conductivity layer, such as a layer of insulating material. Electrically isolating the facing electrode 60B from the upstream electrode of the beam allows the facing electrode 60B and the upstream electrode of the beam to be set at different electric potentials.

[0099] In one embodiment, the second spacer element 72 is configured to electrically connect the facing electrode 60B to ground potential. In one embodiment, as Figure 9 illustrated, the second spacer element 72 includes a non-conductive body 72A and a conductive layer 72B, such as a conductive coating. The layer (e.g., coating) 72B is disposed on the surface closest to the sample 208. The coating 72B may contact the facing electrode 60B. Alternatively or additionally, the coating 72B may contact the first spacer element 71. The second spacer element 72 may provide a circuit path towards ground directly and / or via the first spacer element 71.

[0100] In some embodiments, at least one charged particle optical element set to ground potential includes electronic circuitry. For example, in some embodiments, as Figure 9 illustrated, at least one charged particle optical element set at ground potential includes a detector substrate that includes a detector array 60D. The detector array 60D may include an array of detector elements and / or an integrated circuit (e.g., electronic circuitry) in the detector substrate. In some embodiments, the shielded charged particle optical element 60A includes a detector substrate. Thus, the detector substrate may be the charged particle optical element closest to the sample 208. The detector substrate may be set at ground potential, and / or the detector array 60D may be connected to ground potential. The detector array 60D may face the sample 208. The charged particle optical device may be configured to apply an offset potential to the sample 208 via a sample support. The offset potential may be configured to facilitate the propagation of signal particles emitted from the sample 208 towards the detector array 60D. Thus, there may be an electric potential difference between the sample 208 and the detector array 60D. In addition to facilitating the propagation of signal particles towards the detector array 60D, an electric potential difference may be applied additionally or alternatively.

[0101] The integrated circuit in the detector substrate may include multiple layers. These layers may define one or more circuit device layers. For example, these layers may define complementary metal-oxide-semiconductor (CMOS) circuit devices. Thus, the integrated circuit may include CMOS elements. In one embodiment, the CMOS circuit device includes one or more metal layers. In one embodiment, the integrated circuit is configured to detect signal particles emitted from a sample. For example, the metal layer may include one or more electrodes that may provide a surface of the CMOS circuit device on the detector substrate, which may face the sample 208 during operation. The metal layer may include detector elements configured to detect signal particles. The detector elements may be referred to as capture electrodes. The capture electrode is an example of a sensor unit for detecting signal particles. The power supply and control signals of the CMOS circuit device may be connected to the CMOS circuit device through electrical connections extending from an area outside the integrated circuit to the integrated circuit. The CMOS circuit device may include a logic layer. The logic layer may be located in a layer different from one or more electrodes. The logic layer may include amplifiers, such as transimpedance amplifiers (TIAs), filters, analog-to-digital converters (ADCs), and / or readout logic.

[0102] In some embodiments, the first spacer element 71 contacts the detector substrate on the side of the detector substrate opposite to the sample 208. In one embodiment, as Figure 10 illustrated, at least one conductive body of the first spacer element 71 is electrically connected to the detector array 60D through a via (or vias) 74 that passes through the detector substrate and / or a conductive layer 78 on the surface of the detector substrate. The conductive layer 78 may include a coating. As Figure 10 illustrated, the conductive layer 78 may be disposed on the surface of the detector substrate facing away from the electrode 60B (i.e., downward in the Figure 10 orientation). In one embodiment, the conductive body of the first spacer element 71 (e.g., the conductive layer 71B and / or the doped semiconductor body 71A) is electrically connected to the integrated circuit through the via 74 and / or the conductive layer 78. The via 74 may be referred to as a through substrate via (TSV). The conductive layer 78 may take the form of a redistribution layer and / or be referred to as a redistribution layer. In one arrangement, as Figure 9As shown and described, electrical connection through, for example, a first spacer element 71 acting as a conductive spacer or through a conductive layer 71B can provide a ground potential to the detector substrate 60A. In one arrangement, the conductive layer 71B can extend from the first spacer element 71 towards the beam region 62, for example in a region on the side of the detector substrate opposite the detector array 60D. For example, the detector array 60D can be connected to the conductive layer 71B through vias within or near a region of the detector substrate 60A corresponding to the detector array 60D. The vias can be connected to the detector array 60D via a portion of the conductive layer 78. In one arrangement, the vias directly connect the detector array 60D to the conductive layer 71B.

[0103] In some embodiments, the charged particle device includes a low impedance connection between at least one charged particle optical element (e.g., the shielded charged particle optical element 60A and / or the facing electrode 60B) disposed at ground potential and an external ground potential source. In one embodiment, the impedance of the low impedance connection is less than 20 ohms, desirably less than 10 ohms, desirably less than 5 ohms, desirably less than 2.5 ohms. In one embodiment, the inductance of the low impedance connection is less than 5 nH, desirably less than 3 nH, desirably less than 2 nH, desirably less than 1.5 nH, desirably less than 1 nH. In one embodiment, the resistance of the low impedance connection is less than 10 ohms, desirably less than 5 ohms, desirably less than 3 ohms, desirably less than 2 ohms, desirably less than 1.5 ohms, desirably less than 1 ohm. The external ground source can be a protective grounding component and is typically readily accessible. The protective grounding can include, for example, the structure of a vacuum chamber. Providing the low impedance connection helps to reduce unnecessary voltage fluctuations in the elements disposed at ground potential by facilitating the flow of current to and from ground, thereby maintaining the potential stably at or very close to ground potential. In some embodiments, the low impedance connection is arranged to include a low resistance. In some embodiments, the low impedance connection is arranged to include a low inductance and / or a low capacitance. Providing a low inductance and / or capacitance can reduce or prevent potential harmful voltage oscillations or resonances. Voltage oscillations or resonances can be generated by a discharge event and can lead to a secondary discharge, thereby damaging fragile components. Providing such a low impedance connection can also reduce or eliminate the need for discharge protection elements in the circuitry provided in the charged particle optical module 55 (such as in the detector array 60D). Discharge protection elements with a lower protection capacity can be provided, or the discharge protection elements can be omitted. In one embodiment, the detector array 60D is configured without discharge protection elements. The integrated circuit of the detector array 60D can be diode-less or generally without discharge protection elements. Reducing the capacity of the discharge protection elements or omitting the discharge protection elements (such as diodes (which can be referred to as "protection diodes"), clamping circuits or transistors (e.g., CMOS, bipolar, and IGBT), etc.) can simplify the circuit design and / or improve performance by reducing or eliminating noise sources or other unwanted electrical characteristics. For example, omitting a discharge protection element such as a diode can advantageously improve the noise performance by removing the capacitance associated with the discharge protection element (e.g., the diode), which can, for example, allow a signal-to-noise ratio greater than that in the presence of a diode or a general discharge protection element to be detected.

[0104] In one embodiment, as Figure 7 and Figures 9 - 12As shown, the device includes a cooling channel body 84 that defines a cooling channel 86 for guiding the flow of coolant. The cooling channel body 84 can be conductive. The cooling channel body 84 can be composed of a conductive material such as metal. The low-impedance connection can include an electrical path through the cooling channel body 74. The cooling channel body 84 can be grounded, and at least one charged particle optical element disposed at ground potential can be connected to the cooling channel body 84 through a low-impedance connection. For example, a low-impedance connection can be provided between the detector substrate (e.g., the shielded electron optical element 60A) and / or the detector array 60D and the cooling channel body 84. The connection can include a low-impedance path through the first spacer element 71 and / or a direct connection to the cooling channel body 84. The cooling channel body 84 can be mounted, for example, in a manner that has a high thermal conductivity connection with the detector substrate. Such a connection can also have a low electrical impedance. In Figure 7 and Figures 9 - 12 example, the cooling channel body 84 is directly connected to the detector substrate. In other embodiments, the cooling channel body 84 can be indirectly connected to the detector substrate. For example, the cooling channel body 84 can be positioned such that the first spacer element 71 is located between the cooling channel body 84 and the detector substrate, where the cooling channel body 84 is optionally in contact with the first spacer element 71. The cooling channel body 84 can be configured to serve as a heat sink body (e.g., a block of material with a relatively high heat capacity and thermal conductivity), or be thermally and / or electrically connected to a heat sink body. Such a heat sink body may inherently be bulky and metallic and can thus be used as an efficient ground connection. Such a heat sink body can include a conductive material; the heat sink body can be at least partially composed of a metallic material. In one embodiment, a liquid management system can be provided for driving coolant through the cooling channel 86. As Figure 11 shown, in some embodiments, a low-impedance connection is provided between the detector array 60D and the cooling channel body 84 via a conductive layer 78 and one or more vias 75 (e.g., TSVs).

[0105] In one embodiment, as Figure 7 and Figures 9 - 12As shown, the device includes a support structure 92 configured to mechanically support at least a plurality of charged particle optical elements. Thus, the support structure 92 can be a relatively bulky structure that includes mostly conductive material, such as metal. Accordingly, the support structure 92 can be suitable for use as an efficient ground connection. In the example shown, an electrical insulation barrier 88 is provided between the support structure 92 and the charged particle optical element 60 to electrically isolate the charged particle optical device 60, which may need to be set to a non-ground electrical potential, from the support structure 92. (Note that the electrical insulation barrier can be thermally conductive, e.g., includes a thermally conductive material). The low impedance connection can include a circuit path through the support structure 92. The support structure 92 can be grounded, and at least one charged particle optical element disposed at ground electrical potential can be connected to the support structure 92 through a low impedance connection. For example, a low impedance connection can be provided between the detector substrate (e.g., the shielded electron optical element 60A) and / or the detector array 60D and the support structure 92. The connection can include a low impedance path through the first spacer element 71 and / or a direct connection to the support structure 92. As Figure 12 shown, in some embodiments, a low impedance connection is provided between the detector array 60D and the support structure 92 via the conductive layer 78 and one or more vias 76 (e.g., TSVs). Additionally or alternatively, the low impedance connection can pass through both the cooling channel body 84 and the support structure 92, for example, in series and / or in parallel.

[0106] In some embodiments, as Figures 10 - 12 illustrated, the low impedance connection can include a circuit path through a via that passes through at least one charged particle optical element (e.g., the shielded charged particle optical element 60A) and / or the conductive layer 78 that faces another charged particle optical element (e.g., the facing electrode 60B).

[0107] Attached to or in place of one or more charged particle optical elements including a detector array (the detector array being configured to face away from all other charged particle optical elements of the charged particle optical device 40 that are set to ground potential and / or an equipotential such as ground through a connection having a low impedance), there is one or more charged particle optical elements including a detector array located within the charged particle optical device 40, the detector array being located between controllable charged particle optical elements to have a potential difference relative to the charged particle optical elements including the detector array. The charged particle optical elements including the detector array can have the features of any of the embodiments described herein with reference to the detector substrate 60A. In one arrangement, such a charged particle device including the detector array is located near a charged particle element 60B configured as a shielding element, for example having the same potential as the detector substrate 60A. The shielding element can be fixed by any of the embodiments of the first spacer element 71 disclosed herein. In one embodiment, the shielding element is both upstream and downstream of the beam of the detector substrate (e.g., above and below the detector substrate in one embodiment of the module 55).

[0108] In some embodiments, as Figure 7 and Figures 9 - 12 illustrated, the apparatus includes circuitry electrically connected to at least one charged particle optical element. The circuitry can be remote from the charged particle optical element and connected to ground potential. In Figure 7 and Figures 9 - 12 the example, the circuitry is disposed in the electronic unit 90. The electronic unit 90 can include a printed circuit board (PCB). In some embodiments, as Figures 10 - 12As illustrated in the example, the detector array 60D is electrically connected to the electronic unit 90 via the conductive layer 78 and one or more vias 77 (e.g., TSVs). In one embodiment, the electronic unit 90 is fixed to the detector substrate. The electronic unit 90 may be bonded to the detector substrate. The electronic unit 90 may be fixed to the main surface of the detector substrate. The electronic unit 90 may overlap a portion of the main surface of the detector substrate. The electronic unit 90 may extend laterally beyond the outer edge of the periphery of the detector substrate. In one embodiment, the electronic unit 90 is configured to transmit power to the detector array 60D (e.g., to an integrated circuit formed in the detector substrate). For example, the electronic unit 90 may be electrically connected to a power source configured to supply power to the integrated circuit. Additionally or alternatively, the electronic unit 90 may be configured to transmit signals to the integrated circuit. For example, in one embodiment, the electronic unit 90 is configured to provide a control signal to the integrated circuit. The control signal may be, for example, a control signal for controlling the gain and / or offset of an analog-to-digital converter (ADC) included in the integrated circuit. In one embodiment, the electronic unit 90 is configured to transmit signals from the integrated circuit. For example, in one embodiment, the electronic unit 90 is configured to transmit a signal indicative of the current of signal particles emitted from the sample 208 and detected at the detector array 60D.

[0109] In addition to or instead of including one or more charged particle optical elements including a detector array (where the detector array is set to ground potential and / or an equipotential such as ground by a connection having a low impedance, as disclosed in any of the foregoing embodiments and arrangements), one or more charged particle optical elements include a plurality of electrodes and circuitry for actively controlling the plurality of electrodes, and may be set to ground potential and / or an equipotential such as ground by a connection having a low impedance. Such circuitry for controlling the electrodes may be located external to the charged particle optical element, such as the external electronic unit described with reference to the detector substrate 60A. Additionally or alternatively, the electronic device may include circuitry within the charged particle optical element that includes actively controllable electrodes. The electrodes and / or circuitry may be in the form of CMOS circuitry and / or may have features formed using MEMS processing. Such charged particle optical elements may include an array of strip electrodes, for example for a corrector or a collimator, and the potentials applied to the different electrodes may be controllable. In different embodiments of the charged particle optical element, there may be a multipole array arranged at different holes in the plate of the charged particle optical element, such as one or more electrodes around each hole; each electrode may be individually controlled.

[0110] In some embodiments, the apparatus further includes a plurality of position sensors. The position sensors can be or include a liquid level sensor. The position sensors can be capacitive sensors and / or differential sensors. The position sensors can be positioned on a surface of a charged particle optical element (e.g., a detector substrate) that is configured to face the sample 208. The position sensors can be positioned around and away from the path of the beams of the multi-beams. In one embodiment, the position sensors are connected to a ground potential. In one embodiment, the electronics associated with the position sensors are connected to a ground potential.

[0111] The arrangements of the present disclosure can be implemented as a method.

[0112] A method of projecting charged particles onto a sample 208 is provided. The method includes projecting a plurality of beams of charged particles toward the sample 208 along a plurality of paths using a charged particle optical device 40. The charged particle optical device 40 can take any of the forms described above, particularly with reference to Figures 7 - 12 any of the forms described. The device includes a plurality of charged particle optical elements that define an objective lens, and a plurality of apertures are defined along the path of the beam in the objective lens. The method includes, during the projection of the beam onto the sample 208, maintaining at least two charged particle optical elements at different electric potentials and maintaining at least one charged particle optical element at a ground potential. Any of the arrangements described above with reference to Figures 7 - 12 can be used to implement this function, including any one of the various arrangements disclosed for achieving a low impedance connection between at least one charged particle optical element maintained at a ground potential and an external ground potential source.

[0113] A method of evaluating a sample 208 using charged particles is provided. The method includes projecting charged particles onto the sample using the method of projecting charged particles onto the sample 208 described above. The method includes using a charged particle optical element including a detector array to detect signal particles emitted from the sample 208. The method includes maintaining the charged particle optical element including the detector array (e.g., the detector substrate and / or the detector array in which the detector array is defined) at a ground potential during the detection of the signal particles.

[0114] The foregoing description is illustrative and not restrictive. Accordingly, those skilled in the art will appreciate that modifications can be made as described above without departing from the scope of the following claims and sections.

[0115] Although the invention has been described in connection with various embodiments, those skilled in the art will appreciate other embodiments of the invention by considering the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims and sections.

[0116] The following sections are provided:

[0117] Section 1. A charged particle device for projecting multiple beams of charged particles onto a sample, the device comprising: a sample support configured to support the sample; charged particle optics configured to project the multiple beams of charged particles onto the sample along multiple paths, the device including a plurality of charged particle optical elements that define an objective lens, and a plurality of apertures are defined along the paths of the beams in the plurality of charged particle optical elements, wherein: at least two of the charged particle optical elements are configured to be set at different electric potentials, and at least one of the charged particle optical elements is set at ground potential.

[0118] Section 2. The device according to Section 1, wherein at least two of the charged particle optical elements are configured to face each other.

[0119] Section 3. The device according to Section 2, wherein one of the at least two charged particle optical elements configured to face each other is a facing electrode that defines a continuous conductive surface, the continuous conductive surface being configured to define a plurality of apertures in the facing electrode and electrostatically shield a shielding charged particle optical element facing the facing electrode, protecting the facing electrode from the influence of an electric field, desirably, from the influence of an electric field upstream of the beam in the facing electrode.

[0120] Section 4. The device according to Section 3, including a first spacer element electrically connected to at least one of the charged particle optical elements, desirably, electrically connected to at least the shielding charged particle optical element, desirably, the first spacer element is set at ground potential.

[0121] Section 5. The device according to Section 3 or 4, wherein the shielding charged particle optical element is connected to the facing electrode via the first spacer element.

[0122] Section 6. The device according to Section 4 or 5, wherein the first spacer element contacts a main surface of the facing electrode on a side of the facing electrode closest to the sample.

[0123] Section 7. The device according to any one of Sections 4 to 6, wherein the first spacer element contacts the facing electrode on a peripheral secondary surface of the facing electrode.

[0124] Section 8. The device according to section 4 or 5, wherein the first spacer element is spaced apart from the facing electrode, and desirably, the first spacer element is configured to define a hole, and desirably, in the direction of the path of the beams across the plurality of beams, the hole has a size larger than the size of the facing electrode.

[0125] Section 9. The device according to any one of sections 4 to 8 further includes a second spacer element configured to electrically isolate and support the facing electrode.

[0126] Section 10. The device according to section 9, wherein the facing electrode is connected to an upstream electrode of the beam upstream of the beam of the facing electrode through the second spacer element.

[0127] Section 11. The device according to section 10, wherein the second spacer element is configured to: electrically isolate the facing electrode from the upstream electrode of the beam; and optionally electrically connect the facing electrode to the ground potential via the first spacer element.

[0128] Section 12. The device according to any one of sections 4 to 11, wherein the first spacer element defines at least one conductive body, and the at least one conductive body forms a planar shape, desirably a closed loop or a ring, and the planar shape is configured to be located around the plurality of paths of the beams of the plurality of beams, desirably surrounding the plurality of paths of the beams of the plurality of beams, and the at least one conductive body is set to the ground potential.

[0129] Section 13. The device according to section 12, wherein the at least one conductive body includes a conductive layer on one or both sides of the first spacer element, desirably a coating.

[0130] Section 14. The device according to section 12 or 13, wherein the at least one conductive body includes a doped semiconductor body.

[0131] Section 15. The device according to any one of sections 3 to 11, wherein the charged particle optical shielding element includes a detector substrate, and the detector substrate includes a detector array, and the detector array desirably includes an array of detector elements and / or an integrated circuit in the detector substrate.

[0132] Section 16. The device according to any one of sections 12 to 14, wherein the charged particle optical shielding element includes a detector substrate, and the detector substrate includes a detector array, and the detector array desirably includes an array of detector elements and / or an integrated circuit in the detector substrate.

[0133] Chapter 17. The device according to Chapter 16, wherein the at least one conductive body is electrically connected to the detector array through vias that pass through the detector substrate and / or desirably through a conductive layer, desirably a coating, on the surface of the detector substrate, desirably with the surface facing away from the facing electrode, and desirably the conductive body is electrically connected to the detector array and / or the integrated circuit through the vias and / or the conductive layer.

[0134] Chapter 18. The device according to any one of Chapters 15 to 17, wherein the first spacer element contacts the detector substrate on the side of the detector substrate opposite to the sample.

[0135] Chapter 19. The device according to any one of Chapters 15 to 18, wherein the detector substrate is configured as the charged particle optical element closest to the sample.

[0136] Chapter 20. The device according to Chapter 19, wherein the detector array faces the sample.

[0137] Chapter 21. The device according to any one of Chapters 15 to 20, configured to apply a bias potential to the sample via the sample support, wherein the bias potential is configured to facilitate the propagation of signal particles emitted from the sample to the detector array.

[0138] Chapter 22. The device according to any one of Chapters 15 to 21, wherein the detector substrate is set at ground potential and / or the detector array is connected to ground potential.

[0139] Chapter 23. The device according to any one of Chapters 3 to 22, wherein the facing electrode is set at ground potential.

[0140] Chapter 24. The device according to any one of the preceding chapters, wherein at least one of the charged particle optical elements among the charged particle optical elements set at ground potential includes an electrode of the objective lens.

[0141] Chapter 25. The device according to any one of the preceding chapters, wherein at least one of the charged particle optical elements among the charged particle optical elements set at ground potential includes a detector substrate, the detector substrate includes a detector array, and the detector array desirably includes an array of detector elements and / or an integrated circuit in the detector substrate.

[0142] Chapter 26. The device according to any one of the preceding chapters, including a low-impedance connection between at least one of the charged particle optical elements among the charged particle optical elements set at ground potential and an external ground potential source.

[0143] Article 27. The apparatus according to Article 26, wherein: the apparatus includes a cooling channel body that defines a cooling channel for guiding the flow of coolant; and the low-impedance connection includes a circuit path passing through the cooling channel body.

[0144] Article 28. The apparatus according to Article 26 or 27, wherein: the apparatus includes a support structure configured to mechanically support at least the plurality of charged particle optical elements; and the low-impedance connection includes a circuit path passing through the support structure.

[0145] Article 29. The apparatus according to any one of Articles 26 to 28, wherein the low-impedance connection includes a circuit path passing through a via that passes through at least one of the charged particle optical elements and / or a conductive layer, the conductive layer facing another charged particle optical element among the charged particle optical elements.

[0146] Article 30. The apparatus according to any one of Articles 26 to 29, wherein the low-impedance connection has an impedance of less than 20 ohms.

[0147] Article 31. The apparatus according to any one of Articles 26 to 30, wherein the low-impedance connection has an inductance of less than 5 nH.

[0148] Article 32. The apparatus according to any one of Articles 26 to 31, wherein the low-impedance connection has a resistance of less than 10 ohms.

[0149] Article 33. The apparatus according to any one of the preceding articles, wherein at least one of the charged particle optical elements disposed at ground potential includes electronic circuitry.

[0150] Article 34. The apparatus according to any one of the preceding articles, further comprising circuitry electrically connected to at least one of the charged particle optical elements, the circuitry being remote from the charged particle optical elements and connected to ground potential.

[0151] Article 35. The apparatus according to any one of the preceding articles, further comprising a plurality of position sensors, desirably level sensors, desirably capacitance sensors, desirably differential sensors, the plurality of position sensors being located on the surface of the charged particle optical element configured to face the sample, the position sensors being located around and remote from the path of the plurality of beams, wherein the position sensors are connected to ground potential, and desirably, the electronic devices associated with the position sensors are connected to the ground potential.

[0152] Chapter 36. A method of projecting charged particles onto a sample, the method comprising: using a charged particle optical device to project multiple beams of the charged particles onto the sample along multiple paths, the device comprising a plurality of charged particle optical elements that define an objective lens, and a plurality of apertures being defined along the paths of the beams in the plurality of charged particle optical elements; and during the projection of the beams onto the sample, maintaining at least two of the charged particle optical elements at different electric potentials and maintaining at least one of the charged particle optical elements at ground potential.

[0153] Chapter 37. A method of evaluating a sample using charged particles, the method comprising: projecting charged particles onto the sample using the method according to Chapter 36; detecting signal particles emitted from the sample using a charged particle optical element comprising a detector array; and maintaining the charged particle optical element comprising the detector array at ground potential during the detection of the signal particles.

[0154] Chapter 38. The method according to Chapter 36 or 37, wherein at least two of the charged particle optical elements face each other.

[0155] Chapter 39. The method according to Chapter 38, wherein one of the at least two charged particle optical elements that face each other is a facing electrode that defines a continuous conductive surface, the continuous conductive surface defining a plurality of apertures in the facing electrode and electrostatically shielding a shielded charged particle optical element that the facing electrode faces, shielding the facing electrode from an electric field, desirably from an electric field upstream of the beam in the facing electrode.

[0156] Chapter 40. The method according to Chapter 39, wherein a first spacer element is electrically connected to at least one of the charged particle optical elements, desirably to at least the shielded charged particle optical element, and desirably the first spacer element is set to ground potential.

[0157] Chapter 41. The method according to Chapter 39 or 40, wherein the shielded charged particle optical element is connected to the facing electrode via the first spacer element.

[0158] Chapter 42. The method according to Chapter 40 or 41, wherein the first spacer element contacts a main surface of the facing electrode on a side of the facing electrode closest to the sample.

[0159] Section 43. The method according to any one of Sections 40 to 42, wherein the first spacer element contacts the facing electrode on the peripheral secondary surface of the facing electrode.

[0160] Section 44. The method according to Section 40 or 41, wherein the first spacer element is spaced apart from the facing electrode, desirably, the first spacer element defines a hole, desirably, in the direction of the path of the beams across the plurality of beams, the hole having a size larger than the size of the facing electrode.

[0161] Section 45. The method according to any one of Sections 40 to 44, wherein the second spacer element electrically isolates and supports the facing electrode.

[0162] Section 46. The method according to Section 45, wherein the facing electrode is connected to an upstream electrode of the beam upstream of the beam of the facing electrode through the second spacer element.

[0163] Section 47. The method according to Section 46, wherein the second spacer element: electrically isolates the facing electrode from the upstream electrode of the beam; and optionally electrically connects the facing electrode to the ground potential via the first spacer element.

[0164] Section 48. The method according to any one of Sections 40 to 47, wherein the first spacer element defines at least one conductive body, the at least one conductive body forms a planar shape, desirably a closed loop or a ring, the planar shape is located around the plurality of paths of the beams of the plurality of beams, desirably surrounding the plurality of paths of the beams of the plurality of beams, the at least one conductive body is set to the ground potential.

[0165] Section 49. The method according to Section 48, wherein the at least one conductive body includes a conductive layer on one or both sides of the first spacer element, desirably a coating.

[0166] Section 50. The method according to Section 48 or 49, wherein the at least one conductive body includes a doped semiconductor body.

[0167] Section 51. The method according to any one of Sections 39 to 47, wherein the charged particle shielding optical element includes a detector substrate, the detector substrate includes a detector array, the detector array desirably includes an array of detector elements and / or an integrated circuit in the detector substrate.

[0168] Chapter 52. The method according to any one of Chapters 48 to 50, wherein the shielded charged particle optical element includes a detector substrate, the detector substrate includes a detector array, and the detector array desirably includes an array of detector elements and / or an integrated circuit in the detector substrate.

[0169] Chapter 53. The method according to Chapter 52, wherein the at least one conductive body is electrically connected to the detector array through a via hole that passes through the detector substrate and / or desirably through a conductive layer, desirably a coating, on the surface of the detector substrate, desirably with the surface facing away from the facing electrode, and desirably the conductive body is electrically connected to the detector array and / or the integrated circuit through the via hole and / or the conductive layer.

[0170] Chapter 54. The method according to any one of Chapters 51 to 53, wherein the first spacer element contacts the detector substrate on a side of the detector substrate opposite to the sample.

[0171] Chapter 55. The method according to any one of Chapters 51 to 54, wherein the detector substrate is the charged particle optical element closest to the sample.

[0172] Chapter 56. The method according to Chapter 55, wherein the detector array faces the sample.

[0173] Chapter 57. The method according to any one of Chapters 51 to 56, including applying an offset potential to the sample via the sample support, wherein the offset potential promotes the propagation of signal particles emitted from the sample to the detector array.

[0174] Chapter 58. The method according to any one of Chapters 51 to 57, wherein the detector substrate is set at ground potential and / or the detector array is connected to ground potential.

[0175] Chapter 59. The method according to any one of Chapters 39 to 58, wherein the facing electrode is set at ground potential.

[0176] Chapter 60. The method according to any one of Chapters 36 to 59, wherein at least one of the charged particle optical elements of the charged particle optical elements set at ground potential includes an electrode of the objective lens.

[0177] Chapter 61. The method according to any one of Chapters 36 to 60, wherein at least one of the charged particle optical elements disposed at ground potential includes a detector substrate, the detector substrate includes a detector array, and the detector array desirably includes an array of detector elements and / or an integrated circuit in the detector substrate.

[0178] Chapter 62. The method according to any one of Chapters 36 to 61, including a low impedance connection between at least one of the charged particle optical elements disposed at ground potential and an external ground potential source.

[0179] Chapter 63. The method according to Chapter 62, wherein: a cooling channel body defines a cooling channel for guiding coolant flow; and the low impedance connection includes a circuit path passing through the cooling channel body.

[0180] Chapter 64. The method according to Chapter 62 or 63, wherein: a support structure mechanically supports at least the plurality of charged particle optical elements; and the low impedance connection includes a circuit path passing through the support structure.

[0181] Chapter 65. The method according to any one of Chapters 62 to 64, wherein the low impedance connection includes a circuit path passing through a via, the via passing through at least one of the charged particle optical elements and / or a conductive layer, the conductive layer facing away from another charged particle optical element among the charged particle optical elements.

[0182] Chapter 66. The method according to any one of Chapters 62 to 65, wherein the low impedance connection has an impedance of less than 20 ohms.

[0183] Chapter 67. The method according to any one of Chapters 62 to 66, wherein the low impedance connection has an inductance of less than 5 nH.

[0184] Chapter 68. The method according to any one of Chapters 62 to 67, wherein the low impedance connection has a resistance of less than 10 ohms.

[0185] Chapter 69. The method according to any one of Chapters 36 to 68, wherein at least one of the charged particle optical elements disposed at ground potential includes electronic circuitry.

[0186] Chapter 70. The method according to any one of Chapters 36 to 69, wherein the circuitry is electrically connected to at least one of the charged particle optical elements, the circuitry being remote from the charged particle optical elements and connected to ground potential.

[0187] Chapter 71. The method according to any one of Chapters 36 to 70, wherein a plurality of position sensors, desirably level sensors, desirably capacitive sensors, desirably differential sensors, are located on the surface of the charged particle optical element facing the sample, the position sensors being located around and away from the path of the beams of the multi-beam, wherein the position sensors are connected to a ground potential, and desirably, the electronic device associated with the position sensors is connected to the ground potential.

Claims

1. A charged particle device for projecting multiple beams of charged particles onto a sample, the device comprising: a sample support configured to support the sample; charged particle optics configured to project multiple beams of the charged particles along multiple paths onto the sample, the device including a plurality of charged particle optical elements that define an objective lens, and a plurality of apertures are defined along the paths of the beams in the plurality of charged particle optical elements, wherein: at least two of the charged particle optical elements are configured to be set at different electric potentials, and at least one of the charged particle optical elements is set at ground potential.

2. The device according to claim 1, wherein at least two of the charged particle optical elements are configured to face each other.

3. The device according to claim 2, wherein one of the at least two charged particle optical elements configured to face each other is a facing electrode that defines a continuous conductive surface, the continuous conductive surface being configured to define a plurality of apertures in the facing electrode and electrostatically shield a shielded charged particle optical element faced by the facing electrode, rendering the facing electrode immune to an electric field, desirably an electric field upstream of the beam in the facing electrode.

4. The device according to claim 3, including a first spacer element electrically connected to at least one of the charged particle optical elements, desirably to at least the shielded charged particle optical element, and desirably the first spacer element is set at ground potential.

5. The device according to claim 3 or 4, wherein the shielded charged particle optical element is connected to the facing electrode via the first spacer element.

6. The device according to claim 4 or 5, wherein the first spacer element contacts a main surface of the facing electrode on a side of the facing electrode closest to the sample, and / or the first spacer element contacts the facing electrode on a peripheral secondary surface of the facing electrode.

7. The device according to claim 4 or 5, wherein the first spacer element is spaced apart from the facing electrode, desirably the first spacer element is configured to define an aperture, desirably in a direction spanning the paths of the multiple beams, the aperture having a size larger than the size of the facing electrode.

8. The device according to any one of claims 4 to 7, further including a second spacer element configured to electrically isolate and support the facing electrode.

9. The device according to claim 8, wherein the facing electrode is connected to an upstream electrode upstream of the beam in the facing electrode via the second spacer element, wherein the second spacer element is configured to: electrically isolate the facing electrode from the upstream electrode; and optionally electrically connect the facing electrode to ground potential via the first spacer element.

10. The device according to any one of claims 4 to 9, wherein the first spacer element defines at least one conductive body, the at least one conductive body forming a planar shape, desirably a closed loop or a ring, the planar shape being configured to be located around the plurality of paths of the beams of the multi-beam, desirably surrounding the plurality of paths of the beams of the multi-beam, and the at least one conductive body is set to ground potential.

11. The device according to any one of claims 3 to 10, wherein the charged particle optical shielding element includes a detector substrate, the detector substrate including a detector array, the detector array desirably including an array of detector elements and / or an integrated circuit in the detector substrate.

12. The device according to claim 11, wherein the first spacer element contacts the detector substrate on a side of the detector substrate opposite to the sample.

13. The device according to claim 11 or 12, wherein the detector substrate is set at ground potential and / or the detector array is connected to ground potential.

14. The device according to any one of the preceding claims, including a low-impedance connection between at least one charged particle optical element of the charged particle optical elements set at ground potential and an external ground potential source.

15. A method of projecting charged particles onto a sample, the method comprising: using a charged particle optical device to project a multi-beam of the charged particles onto the sample along a plurality of paths, the device including a plurality of charged particle optical elements, the plurality of charged particle optical elements defining an objective lens, and a plurality of apertures being defined along the paths of the beams in the plurality of charged particle optical elements; and during the projection of the beams onto the sample, maintaining at least two of the charged particle optical elements at different potentials and maintaining at least one of the charged particle optical elements at ground potential.

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