Multi-charged particle beam apparatus and method

Abstract

Systems and methods to mitigate coulomb effects in a multi-beam device are disclosed. The multi-beam apparatus may include a charged particle source configured to generate a primary charged particle beam along a primary optical axis; a first array of apertures, the first array of apertures comprising a first plurality of apertures having a shape and configured to generate a plurality of primary beamlets derived from the primary charged particle beam; a condenser lens including a plane adjustable along the primary optical axis; and a second array of apertures, the second array of apertures comprising a second plurality of apertures configured to generate probe beamlets corresponding to the plurality of beamlets, wherein each probe beamlet of the plurality of probe beamlets comprises a portion of charged particles of a corresponding primary beamlet based at least on a position of a plane of the condenser lens and a characteristic of the second aperture array.

Description

[0001] This application is a divisional application of an application with a filing date of May 18, 2020, application number 202080039403.0, and invention name “Multi-charged particle beam device and method”. Technical Field

[0002] Embodiments provided herein disclose a multi-beam apparatus, and more particularly relate to a multi-beam charged-particle microscope including an aperture array having apertures configured to accommodate variations in beam current and beam position and to mitigate Coulomb effects. Background Art

[0003] During the manufacture of integrated circuits (ICs), unfinished or completed circuit components are inspected to ensure that they are manufactured according to design and are free of defects. Inspection systems utilizing optical microscopes or charged particle (e.g., electron) beam microscopes, such as scanning electron microscopes (SEMs), can be employed. As the physical size of IC components continues to shrink, the accuracy and yield of defect detection become more important. Although multiple electron beams can be used to increase production throughput, the limitations of the probe current variation may limit the imaging resolution desired for reliable defect detection and analysis, resulting in inspection tools being insufficient for their intended purpose. Summary of the invention

[0004] In one aspect of the present disclosure, a charged particle beam device is disclosed. The charged particle beam device includes: a charged particle source configured to generate a primary charged particle beam along a primary optical axis; a first aperture array including a first plurality of apertures configured to generate a plurality of primary beamlets from the primary charged particle beam; a focusing lens including a plane that can be adjusted along the primary optical axis; and a second aperture array including a second plurality of apertures configured to generate a plurality of detection beamlets. Each of the plurality of detection beamlets includes a portion of charged particles of the corresponding primary beamlet, and the portion of charged particles is determined based at least on the position of the plane of the focusing lens and the characteristics of the second aperture array.

[0005] The first aperture array may include a pre-beamlet forming aperture array disposed between the charged particle source and the focusing lens. The first aperture array may include an on-axis aperture configured to generate an on-axis beamlet, which is incident on the on-axis aperture of the second aperture array. The first aperture array may also include an off-axis aperture configured to generate an off-axis beamlet, which is incident on a corresponding off-axis aperture of the second aperture array. The off-axis aperture of the first aperture array may include an elongated aperture having a rounded end and a gradually narrowing width. The off-axis aperture of the first aperture array may include an elongated aperture having a rounded end and a gradually narrowing width, and having a curved form. The off-axis aperture may be oriented so that the width gradually narrows toward the primary optical axis.

[0006] The focusing lens can be configured to cause a portion of the off-axis beamlets to form a corresponding detection beamlet in the plurality of detection beamlets. The focusing lens can be configured to cause a portion of the off-axis beamlets to form a corresponding detection beamlet in the plurality of detection beamlets. The second plurality of holes can be configured to determine the size and shape of the plurality of detection beamlets. The characteristics of the second hole array can include at least one of the size, shape and arrangement of the second plurality of holes. The focusing lens can include an electrostatic lens, an electromagnetic lens, or an electromagnetic compound lens.

[0007] The first plurality of holes may include a plurality of off-axis holes. The plurality of off-axis holes may include a hole in which a first off-axis hole overlaps a second off-axis hole, wherein the first off-axis hole enables the second hole array to generate a first off-axis detection beamlet, and the second off-axis hole enables the second hole array to generate a second off-axis detection beamlet. Each of the plurality of off-axis holes of the first hole array may be separated by a substrate material of the first hole array. The off-axis holes of the first hole array may be substantially circular, and the area of ​​the on-axis hole of the first hole array is substantially similar to the area of ​​the off-axis hole.

[0008] In another aspect of the present disclosure, a first aperture array of a charged particle beam device is disclosed. The first aperture array may include a first plurality of apertures configured to generate a plurality of primary beamlets from a primary charged particle beam. Portions of charged particles of primary beamlets in the plurality of primary beamlets form corresponding detection beamlets in a plurality of detection beamlets, and the portion of charged particles is determined based at least on a position of a plane of a focusing lens and a characteristic of a second aperture array, wherein the second aperture array is configured to generate a plurality of detection beamlets.

[0009] In another aspect of the present disclosure, a method for observing a sample using a multi-beam device is disclosed. The method may include: activating a charged particle source to generate a primary charged particle beam; using a first aperture array, generating a plurality of primary sub-beams from the primary charged particle beam; using a second aperture array, generating a plurality of detection sub-beams corresponding to the plurality of primary sub-beams; adjusting the position of a plane of a condenser lens along a primary optical axis with respect to the first aperture array and the second aperture array; and generating a plurality of detection spots incident on a sample surface from the plurality of detection sub-beams, wherein each of the plurality of detection sub-beams includes a portion of charged particles of a corresponding primary sub-beam in the plurality of primary beams, and wherein the portion of charged particles is determined based at least on the position of the plane of the condenser lens and a characteristic of the second aperture array.

[0010] Adjusting the position of the plane of the focusing lens can modify the characteristics of the detection beamlet, including the current of the detection beamlet. Generating the plurality of primary beamlets can include: generating on-axis beamlets and off-axis beamlets. The method can also include: using the focusing lens to cause a portion of the off-axis beamlets to form a corresponding detection beamlet in the plurality of detection beamlets.

[0011] In yet another aspect of the present disclosure, a non-transitory computer-readable medium storing an instruction set is disclosed, the instruction set being executable by one or more processors of a multi-beam device having a first aperture array and a second aperture array. The instruction set may enable the multi-beam device to perform a method for observing a sample using the multi-beam device. The method may include: activating a charged particle source to generate a primary charged particle beam; and adjusting the position of a plane of a focusing lens about the first aperture array and the second aperture array along a primary optical axis, wherein the first aperture array is configured to generate a plurality of primary sub-beams from the primary charged particle beam using a first plurality of apertures, a portion of the charged particles of the primary sub-beams in the plurality of primary sub-beams forming corresponding detection sub-beams, and the portion of the charged particles is determined based at least on the position of the plane of the focusing lens and the characteristics of the second aperture array.

[0012] In another aspect of the present disclosure, a charged particle beam device is disclosed. The charged particle beam device may include: a charged particle source configured to generate a primary charged particle beam along a primary optical axis; a first hole array including a plurality of hole sets configured to form a plurality of primary sub-beams from the primary charged particle beam; a condenser lens disposed on a plane perpendicular (normal) to the primary optical axis; and a second hole array including a plurality of holes configured to generate a plurality of detection sub-beams. The detection sub-beams in the plurality of detection sub-beams are associated with the hole sets of the first hole array, and the holes in the hole sets forming the detection sub-beams are determined based at least on the characteristics of the condenser lens.

[0013] The first aperture array may include a pre-beamlet forming aperture array disposed between the charged particle source and the focusing lens. The first aperture array may also include an on-axis aperture configured to generate an on-axis primary beamlet, which is incident on the on-axis aperture of the second aperture array. The on-axis aperture of the first aperture array may be substantially circular. The first aperture array may include a plurality of off-axis aperture sets configured to generate a plurality of off-axis primary beamlets, which are incident on corresponding off-axis apertures of the second aperture array.

[0014] A set of the plurality of off-axis aperture sets may include apertures arranged along a curved path. A set of the plurality of off-axis aperture sets may include at least two apertures having different sizes. A set of the plurality of off-axis aperture sets may include apertures sized to determine a current of a corresponding primary beamlet. A set of the plurality of off-axis aperture sets may include apertures having uniform spacing. A set of the plurality of off-axis aperture sets may include apertures having non-uniform spacing. A plurality of off-axis aperture sets may include apertures having a circular, rectangular, elliptical, or polygonal cross-section.

[0015] The condenser lens may be configured to cause a primary beamlet in the plurality of primary beamlets to form a corresponding detection beamlet in the plurality of detection beamlets. The condenser lens may include an electrostatic lens, an electromagnetic lens, or an electromagnetic compound lens. The second aperture array may include a beam limiting aperture array disposed between the condenser lens and the objective lens. The second plurality of apertures may be configured to determine the size and shape of the plurality of detection beamlets.

[0016] In another aspect of the present disclosure, a first aperture array of a charged particle beam device is disclosed. The first aperture array may include a plurality of aperture sets configured to form a plurality of primary beamlets from a primary charged particle beam. A detection beamlet in a plurality of detection beamlets is associated with a set in a plurality of aperture sets of the first aperture array, and the apertures in the aperture set forming the detection beamlets are determined based at least on the characteristics of a focusing lens.

[0017] In another aspect of the present disclosure, a method for observing a sample using a multi-beam device is disclosed. The method may include: activating a charged particle source to generate a primary charged particle beam; generating a plurality of primary sub-beams from the primary charged particle beam using a first aperture array; adjusting the position of a plane of a condenser lens along a primary optical axis with respect to the first aperture array and the second aperture array; and generating a plurality of detection spots incident on a sample surface from a plurality of detection sub-beams. A detection sub-beam in the plurality of detection sub-beams may be associated with an aperture set of the first aperture array, and an aperture in the aperture set forming the detection sub-beam is determined based at least on a characteristic of the condenser lens.

[0018] Adjusting the position of the plane of the condenser lens may modify the characteristics of the detection beamlets. Adjusting the position of the plane of the condenser lens may modify the current of the detection beamlets. Generating the plurality of primary beamlets may include generating on-axis primary beamlets and off-axis primary beamlets.

[0019] The method of observing a sample using a multi-beam device may further include: using a condenser lens to form an off-axis primary beamlet into a corresponding detection beamlet of a plurality of detection beamlets.

[0020] In yet another aspect of the present disclosure, a non-transitory computer-readable medium storing an instruction set is disclosed, the instruction set being executable by one or more processors of a multi-beam device having a first aperture array and a second aperture array. The instruction set may enable the multi-beam device to perform a method for observing a sample using the multi-beam device. The method may include: activating a charged particle source to generate a primary charged particle beam; and adjusting the position of a plane of a focusing lens about the first aperture array and the second aperture array along a primary optical axis, wherein the first aperture array is configured to generate a plurality of primary sub-beams from the primary charged particle beam using a plurality of aperture sets, the primary sub-beams in the plurality of primary sub-beams forming corresponding detection sub-beams, and the apertures in the aperture set forming the detection sub-beams are determined based at least on the characteristics of the focusing lens.

[0021] In yet another aspect of the present disclosure, a charged particle beam device is disclosed. The device may include a first aperture array, the first aperture array including a first plurality of apertures, the first plurality of apertures being configured to generate a plurality of primary sub-beams from a primary charged particle beam. The apertures in the first plurality of apertures may include: a first aperture plate configured to be at a first voltage; and a second aperture plate configured to be at a second voltage different from the first voltage, for generating an electric field, the electric field enabling adjustment of the path of the charged particles of the primary charged particle beam. The device may also include a third aperture plate, the third aperture plate being configured to be at a third voltage substantially similar to the first voltage. The device may also include: a condenser lens, the condenser lens including a plane that can be adjusted along the primary optical axis; and a second aperture array, the second aperture array including a second plurality of apertures, the second plurality of apertures being configured to generate a plurality of probe sub-beams, wherein each of the plurality of probe sub-beams includes a portion of the charged particles of the corresponding primary sub-beam, and the portion of the charged particles is based at least on the position of the plane of the condenser lens and the characteristics of the second aperture array.

[0022] The first voltage and the third voltage may include a reference voltage. The second aperture plate may include a charged particle beam deflector configured to adjust the path of the charged particles in response to electrical activation. The charged particle beam deflector may include a monopole deflector or a multipole deflector. The electrical activation of the second aperture plate may include a voltage signal being applied to generate an electric field. The path of the charged particles is adjusted based on the characteristics of the voltage signal applied to the second aperture plate. The characteristics of the voltage signal may include polarity or amplitude. The apertures in the first plurality of apertures may include a first aperture in the first aperture plate, a second aperture in the second aperture plate, and a third aperture in the third aperture plate, wherein the second aperture plate is disposed between the first aperture plate and the third aperture plate, and wherein the geometric centers of the first aperture, the second aperture, and the third aperture are aligned. The first aperture and the second aperture may be different in size, and the first aperture and the third aperture may be substantially similar in size.

[0023] The third aperture plate may be configured to block a portion of the charged particles from leaving the second aperture. The first aperture array may include a pre-beamlet forming aperture array disposed between the charged particle source and the focusing lens. The first aperture array may include an on-axis aperture configured to generate an on-axis beamlet, which is incident on the on-axis aperture of the second aperture array. The first aperture array includes an off-axis aperture configured to generate an off-axis beamlet, which is incident on a corresponding off-axis aperture in the second aperture array. The off-axis aperture of the first aperture array may include an elongated aperture having a rounded end and a gradually narrowing width. The off-axis aperture of the first aperture array may include an elongated aperture having a rounded end and a gradually narrowing width, and having a curved form. The off-axis aperture may be oriented so that the width gradually narrows toward the primary optical axis.

[0024] The focusing lens can be configured to cause a portion of the off-axis beamlets to form a corresponding detection beamlet in the plurality of detection beamlets. The focusing lens can be configured to cause a portion of the off-axis beamlets to form a corresponding detection beamlet in the plurality of detection beamlets. The second plurality of holes can be configured to determine the size and shape of the plurality of detection beamlets. The characteristics of the second hole array can include at least one of the size, shape and arrangement of the second plurality of holes. The focusing lens can include an electrostatic lens, an electromagnetic lens, or an electromagnetic compound lens.

[0025] The first plurality of holes may include a plurality of off-axis holes. The plurality of off-axis holes may include a hole in which a first off-axis hole overlaps a second off-axis hole, wherein the first off-axis hole enables the second hole array to generate a first off-axis detection beamlet, and the second off-axis hole enables the second hole array to generate a second off-axis detection beamlet. Each of the plurality of off-axis holes of the first hole array may be separated by a substrate material of the first hole array. The off-axis holes of the first hole array may be substantially circular, and the area of ​​the on-axis hole of the first hole array is substantially similar to the area of ​​the off-axis hole.

[0026] In another aspect of the present disclosure, a method for observing a sample using a charged particle beam device is disclosed. The method may include: activating a charged particle source to generate a primary charged particle beam; using a first aperture plate and a second aperture plate of a first aperture array, generating a plurality of primary sub-beams from the primary charged particle beam, wherein the first aperture plate is operated at a first voltage, and the second aperture plate is operated at a second voltage different from the first voltage, for adjusting the path of the charged particles leaving the first aperture plate; using a second aperture array, generating a plurality of detection sub-beams corresponding to the plurality of primary sub-beams; and generating a plurality of detection spots incident on a sample surface from the plurality of detection sub-beams. The method may also include: operating a third aperture plate at a third voltage substantially similar to the first voltage, wherein the first voltage and the third voltage include a reference voltage. The method may also include: adjusting the path of the charged particles by electrically activating the second aperture plate, wherein electrically activating the second aperture plate includes applying a voltage signal to generate an electric field. The method may further include: adjusting the position of a plane of a condenser lens with respect to the first array of holes and the second array of holes along the primary optical axis, wherein adjusting the position of the plane of the condenser lens modifies characteristics of the plurality of probe beamlets, and wherein adjusting the position of the plane of the condenser lens modifies currents of the plurality of probe beamlets, and wherein generating the plurality of primary beamlets includes generating on-axis beamlets and off-axis beamlets. The method may further include: using the condenser lens so that portions of the off-axis beamlets form corresponding ones of the plurality of probe beamlets.

[0027] In yet another aspect of the present disclosure, a non-transitory computer-readable medium storing an instruction set is disclosed, the instruction set being executable by one or more processors of a multi-beam device having a first aperture array and a second aperture array. The instruction set may enable the multi-beam device to perform a method for observing a sample using the multi-beam device. The method may include: activating a charged particle source to generate a primary charged particle beam; using a first aperture plate, a second aperture plate, and a third aperture plate of the first aperture array, generating a plurality of primary sub-beams from the primary charged particle beam, wherein the first aperture plate and the third aperture plate are operated substantially at a first voltage, and the second aperture plate is operated at a second voltage different from the first voltage, for adjusting the path of the charged particles leaving the first aperture plate; using a second aperture array, generating a plurality of detection sub-beams corresponding to the plurality of primary sub-beams; and generating a plurality of detection spots incident on the sample surface from the plurality of detection sub-beams.

[0028] In yet another aspect of the present disclosure, a charged particle beam device is disclosed. The device may include a first aperture array, the first aperture array including a first plurality of apertures, the first plurality of apertures being configured to generate a plurality of primary beamlets from a primary charged particle beam. The apertures in the first plurality of apertures may include: a first aperture plate configured to be at a first voltage; and a second aperture plate configured to be at a second voltage different from the first voltage, for generating an electric field between the first aperture plate and the second aperture plate; and a second aperture array configured to generate a detection beamlet from the corresponding primary beamlet, wherein the beam current of the detection beamlet is adjustable. The electric field between the first aperture plate and the second aperture plate may be substantially fixed, and wherein the beam current is discretely adjusted based on the size of the apertures in the first plurality of apertures in the first aperture array. The electric field between the first aperture plate and the second aperture plate may be adjustable, and wherein the beam current is adjusted based on the electric field between the first aperture plate and the second aperture plate.

[0029] In another aspect of the present disclosure, a method for observing a sample using a charged particle beam device is disclosed. The method may include: activating a charged particle source to generate a primary charged particle beam; using a first aperture plate and a second aperture plate of a first aperture array, generating a plurality of primary sub-beams from the primary charged particle beam, wherein the first aperture plate operates at a first voltage and the second aperture plate operates at a second voltage different from the first voltage, for adjusting the path of the charged particles leaving the first aperture plate; using a second aperture array, generating a detection sub-beam from the corresponding primary sub-beam, wherein the beam current of the detection sub-beam is adjustable; and generating a detection spot incident on the sample surface from the detection sub-beam. The method may also include adjusting the path of the charged particles, wherein adjusting the path includes deflecting the charged particles based on an electric field formed between the first aperture plate and the second aperture plate. The electric field between the first aperture plate and the second aperture plate may be substantially fixed, and wherein adjusting the beam current of the detection sub-beam is based on the size of the apertures in the first aperture array. The electric field between the first aperture plate and the second aperture plate may be adjustable, and wherein adjusting the beam current of the detection sub-beam includes adjusting the electric field between the first aperture plate and the second aperture plate. Deflecting the charged particles may be caused by electrically activating the second aperture plate by applying a voltage signal to generate an electric field.The method may further include operating the third aperture plate at a third voltage substantially similar to the first voltage, wherein the first voltage and the third voltage comprise a reference voltage.

[0030] In another aspect of the present disclosure, a non-transitory computer-readable medium stores an instruction set that can be executed by one or more processors of a multi-beam device having a first aperture array and a second aperture array to cause the multi-beam device to perform a method. The method may include: activating a charged particle source to generate a primary charged particle beam; using a first aperture plate and a second aperture plate of the first aperture array, generating a plurality of primary sub-beams from the primary charged particle beam, wherein the first aperture plate operates at a first voltage, and the second aperture plate operates at a second voltage different from the first voltage, for adjusting the path of the charged particles leaving the first aperture plate; using the second aperture array, generating a detection sub-beam from the corresponding primary sub-beam, wherein the beam current of the detection sub-beam is adjustable; and generating a detection spot incident on a sample surface from the detection sub-beam.

[0031] In another aspect of the present disclosure, a charged particle beam device is disclosed. The device may include: a pre-beamlet forming hole set configured to form multiple primary beamlets from a primary charged particle beam; and a beam limiting hole configured to form a detection beamlet from the corresponding primary beamlets, wherein the beam current of the detection beamlet is determined based on the characteristics of the holes in the pre-beamlet forming hole set that form the primary beamlets. The characteristics of the holes in the pre-beamlet forming hole set may include the size, shape or position of the holes. The beam current of the detection beamlet can be discretely adjusted based on the size of the holes in the pre-beamlet forming hole set. The device may include: a first array of multiple pre-beamlet forming hole sets; and a second array of multiple beam limiting holes, which is arranged downstream of the first array along the primary optical axis of the primary charged particle beam. The holes in the pre-beamlet forming hole set that form the detection beamlet can be determined based on at least the characteristics of a focusing lens, wherein the characteristics of the focusing lens may include the position of the plane of the focusing lens along the primary optical axis. The position change of the plane of the focusing lens can be configured to affect the beam current of the detection beamlet. The condenser lens can be configured to affect the beam current of the probe beamlet by directing portions of the primary charged particle beam through different apertures in the pre-beamlet forming aperture set. The condenser lens at a first position in the plane can be configured to cause a first portion of the primary charged particle beam to pass through a first aperture in the pre-beamlet forming aperture set to form a first primary beamlet; and the condenser lens at a second position in the plane can be configured to cause a second portion of the primary charged particle beam to pass through a second aperture in the pre-beamlet forming aperture set to form a second primary beamlet.

[0032] The first array may include an on-axis hole configured to generate an on-axis primary beamlet that is incident on an on-axis hole of a second array, and the set of pre-beamlet forming holes may include a plurality of off-axis pre-beamlet forming holes configured to generate off-axis primary beamlets that are incident on corresponding off-axis beam limiting holes in the second array. Each of the off-axis pre-beamlet forming holes may be separated by a substrate material of the first array. The plurality of off-axis pre-beamlet forming holes may be arranged along a curved path. The plurality of off-axis pre-beamlet forming holes may include at least two holes having different sizes. The sizes of the plurality of off-axis pre-beamlet forming holes may be arranged to determine the beam current of the primary beamlets generated when passing through the holes in the plurality of off-axis pre-beamlet forming holes. The holes in the plurality of off-axis pre-beamlet forming holes may have uniform spacing or non-uniform spacing.

[0033] Other advantages of the embodiments of the present disclosure will become apparent from the following description taken in conjunction with the accompanying drawings set forth therein, by way of illustration and example, of certain embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1is a schematic diagram illustrating an exemplary electron beam inspection (EBI) system consistent with embodiments of the present disclosure.

[0035] Figure 2 is a schematic diagram illustrating an exemplary electron beam tool consistent with embodiments of the present disclosure, the exemplary electron beam tool can be Figure 1 Portions of an exemplary electron beam inspection system.

[0036] Figure 3 is a schematic diagram illustrating an exemplary configuration of an adjustable condenser lens in a multi-beam device consistent with an embodiment of the present disclosure.

[0037] Figures 4A to 4C It is a diagram consistent with the embodiment of the present disclosure Figure 3 Schematic diagram of exemplary charged particle beam distribution for different probe currents on the aperture array in a multi-beam device.

[0038] Figures 5A to 5C It is a diagram consistent with the embodiment of the present disclosure Figure 3 Schematic diagram of exemplary charged particle beam distribution for different probe currents on the aperture array in a multi-beam device.

[0039] Fig. 6A and 6B is a schematic diagram illustrating an exemplary arrangement of elongated holes of a hole array consistent with embodiments of the present disclosure.

[0040] Fig. 7A and 7B is a schematic diagram illustrating an exemplary curved aperture of an aperture array consistent with embodiments of the present disclosure.

[0041] Fig. 8A and 8B is a schematic diagram illustrating an exemplary arrangement of apertures of an aperture array in a multi-beam device consistent with an embodiment of the present disclosure.

[0042] Fig. 9 It is a diagram consistent with the embodiment of the present disclosure Figure 3 Schematic diagram of an exemplary arrangement of apertures of a beam-limiting aperture array in a multi-beam device.

[0043] Fig.10 is a schematic diagram illustrating exemplary projections of partially overlapping apertures of an aperture array in a multi-beam device consistent with embodiments of the present disclosure.

[0044] Fig.11A It is a diagram consistent with the embodiment of the present disclosure Fig.10 Schematic diagram of an exemplary arrangement of merged wells of a well array.

[0045] Fig. 11B It is a diagram consistent with the embodiment of the present disclosure Fig.10 An exemplary arrangement of holes of a hole array.

[0046] Fig. 11C The diagram is consistent with the embodiment of the present disclosure. Fig. 11B The relationship between the spot size of the aperture-forming beamlet and the beam current.

[0047] Fig.11D The present invention is consistent with the embodiment of the present invention. Fig.10 An exemplary arrangement of holes of a hole array.

[0048] Fig.11E is an expanded view illustrating an exemplary aperture of an active aperture array consistent with embodiments of the present disclosure.

[0049] Fig.11F The diagram is consistent with the embodiment of the present disclosure. Fig.11E Cross-sectional view of an exemplary hole.

[0050] Fig.12 is a process flow diagram representing an exemplary method of viewing a sample using a multi-beam inspection tool consistent with embodiments of the present disclosure.

[0051] Fig.13 is a process flow diagram representing an exemplary method of viewing a sample using a multi-beam inspection tool consistent with embodiments of the present disclosure.

[0052] Fig.14 is a process flow diagram representing an exemplary method of viewing a sample using a multi-beam inspection tool consistent with embodiments of the present disclosure. DETAILED DESCRIPTION

[0053] Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings, wherein, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments set forth in the following description of the exemplary embodiments do not represent all embodiments. On the contrary, they are merely examples of devices and methods consistent with various aspects related to the disclosed embodiments as described in the appended claims. For example, although some embodiments are described in the context of using electron beams, the present disclosure is not limited thereto. Other types of charged particle beams can be similarly applied. In addition, other imaging systems can be used, such as optical imaging, photoelectric detection, x-ray detection, etc.

[0054] Electronic devices are made up of circuits formed on a silicon wafer called a substrate. Many circuits can be formed together on the same silicon wafer and are called an integrated circuit or IC. The size of these circuits has been reduced significantly so that more circuits can be fitted on a substrate. For example, the IC chip in a smartphone can be like a miniature Figure 1The chip is as small as a 12-inch MT but may include more than 2 billion transistors, each less than 1 / 1000 the size of a human hair.

[0055] Manufacturing these extremely small ICs is a complex, time-consuming, and expensive process that typically involves hundreds of individual steps. An error in even one step can result in a defect in the finished IC, rendering it unusable. Therefore, one goal of the manufacturing process is to avoid such defects in order to maximize the number of functional ICs manufactured in the process, i.e., to improve the overall yield of the process.

[0056] An integral part of improving yield is monitoring the chip manufacturing process to ensure that it is producing an adequate number of functional integrated circuits. One way to monitor the process is to inspect the chip circuit structures at various stages of their formation. Inspection can be performed using a scanning electron microscope (SEM). The SEM can be used to image these extremely small structures, in effect taking a "picture" of the structure. The image can be used to determine if the structure was formed correctly and if it was formed in the correct location. If the structure is defective, the process can be adjusted to make the defect less likely to occur again.

[0057] Although multi-charged beam particle imaging systems (such as multi-beam SEM) can be used to increase wafer inspection throughput, the imaging resolution of multi-beam SEM may be negatively affected by the Coulomb interaction effect. In order to achieve high throughput, it is desired that the beam contains as many electrons as possible. However, due to the repulsive Coulomb interactions between electrons, it is difficult to confine a large number of electrons in a very small volume. Moreover, these interactions may widen the width of the beam and change the flight direction of the electrons. Therefore, the detection spot will be larger, which has a negative impact on the overall resolution of the SEM. Therefore, in order to maintain the high resolution of the multi-beam SEM, it is desirable to mitigate the Coulomb interaction effect.

[0058] To mitigate the Coulomb interaction effect, an aperture array can be placed near the electron source to cut off peripheral electrons or split the primary electron beam into multiple beamlets. However, adjusting the probe beam current to adjust the resolution may cause the beam path through the aperture array to change. One of the multiple problems that may be encountered is that the apertures of the aperture array may not be configured to allow beams of various sizes and positions to pass through while maintaining a small enough area to mitigate the Coulomb interaction effect.

[0059] Additionally, because imaging resolution may be adversely affected by Coulomb interaction effects, it may be desirable to maintain uniformity in the overall area of ​​the apertures despite their non-uniform shape to accommodate variations in the probe beam current. For example, variations in the Coulomb interaction effect between apertures of an aperture array may result in non-uniformity in regional resolution within the same image, thereby affecting a user's ability to detect and identify defects.

[0060] In conventional SEM and multi-beam SEM, the size of the detection electron beam or the detection spot size can determine the imaging resolution. For example, a large detection spot with a high beam current may result in poor resolution, and a small detection spot with a low beam current may result in better resolution. The poor imaging resolution caused by a large beam spot size may be partially attributed to the enhanced Coulomb interaction effect in a high current beam.

[0061] A wide range of beam currents may be desired in a multi-beam SEM tool to perform various operations during wafer inspection. For example, a high current beam may be used to perform low resolution, macroscopic inspection of a large area on a wafer, and a low current, high resolution scan may be desired to perform a thorough defect investigation at the micro or nano scale. One of the many ways to generate a wide range of beam currents from a single electron source in a multi-beam SEM may include increasing the size or length of the holes through which the electrons can pass. However, multiple large holes may not only increase the Coulomb interaction effect, but may also negatively affect the mechanical integrity of the hole array. Therefore, it may be desirable to have an imaging tool, such as a multi-beam SEM, that is capable of providing a wide range of beam currents while reducing the Coulomb interaction effect and maintaining the mechanical integrity of the hole array.

[0062] In some embodiments of the present disclosure, a multi-beam device may include an aperture array including a plurality of elongated apertures having a gradually narrowing width and configured to generate a plurality of beamlets associated with a primary charged particle beam. The device may also include a focusing lens on an adjustable plane along the primary optical axis and a second aperture array including a plurality of apertures configured to generate detection beamlets. The shape of the first plurality of apertures is based on the paths of the corresponding beamlets associated with the adjustable detection current of the detection beamlets, the adjustability of the plane of the focusing lens, and the characteristics of the second aperture array, such as the size, shape, and positioning of the apertures.

[0063] In some embodiments of the present disclosure, a multi-beam device may include a first aperture array including a plurality of aperture sets configured to form a plurality of primary beamlets from a primary charged particle beam. The device may also include a second aperture array including a plurality of apertures configured to generate a plurality of detection beamlets. The detection beamlets may be associated with the aperture sets, and the apertures in the aperture sets forming the detection beamlets may be determined based at least on the characteristics of the condenser lens.

[0064] For the sake of clarity, the relative sizes of the components in the drawings may be exaggerated. In the following description of the drawings, the same or similar reference numerals refer to the same or similar components or entities, and only the differences with respect to the individual embodiments are described. As used herein, unless otherwise specifically provided, the term "or" covers all possible combinations, except that it is not feasible. For example, if it is specified that a component can include A or B, then unless otherwise specifically provided or not feasible, the component can include A or B or A and B. As a second example, if it is specified that a component can include A, B or C, then unless otherwise specifically provided or not feasible, the component can include A or B or C or A and B or A and C or B and C or A and B and C.

[0065] Now refer to Figure 1 , Figure 1 An exemplary electron beam inspection (EBI) system 100 consistent with embodiments of the present disclosure is illustrated. Figure 1 As shown, the charged particle beam inspection system 100 includes a main chamber 10, a load lock chamber 20, an electron beam tool 40, and an equipment front end module (EFEM) 30. The electron beam tool 40 is located in the main chamber 10. Although the description and drawings refer to electron beams, it should be understood that the embodiments are not intended to limit the present disclosure to specific charged particles.

[0066] The EFEM 30 includes a first loading port 30a and a second loading port 30b. The EFEM 30 may include additional loading ports. The first loading port 30a and the second loading port 30b receive wafer front opening pods (FOUPs) containing wafers (e.g., one or more semiconductor wafers made of (multiple) other materials) or samples (wafers and samples are collectively referred to as "wafers" hereinafter) to be inspected. One or more robotic arms (not shown) in the EFEM 30 deliver the wafers to the load lock chamber 20.

[0067] The load lock chamber 20 is connected to a load / lock vacuum pump system (not shown) that removes gas molecules in the load lock chamber 20 to reach a first pressure below atmospheric pressure. After reaching the first pressure, one or more robotic arms (not shown) transport the wafer from the load lock chamber 20 to the main chamber 10. The main chamber 10 is connected to a main chamber vacuum pump system (not shown) that removes gas molecules in the main chamber 10 to reach a second pressure below the first pressure. After reaching the second pressure, the wafer is subjected to inspection by an electron beam tool 40. In some embodiments, the electron beam tool 40 may include a single beam inspection tool. In other embodiments, the electron beam tool 40 may include a multi-beam inspection tool.

[0068] The controller 50 may be electrically connected to the electron beam tool 40 and may also be electrically connected to other components. The controller 50 may be a computer configured to perform various controls of the charged particle beam inspection system 100. The controller 50 may also include processing circuitry configured to perform various signal and image processing functions. Figure 1 Controller 50 is shown as being outside the structure including main chamber 10, load lock chamber 20 and EFEM 30, but it is understood that controller 50 may be part of the structure.

[0069] Although the present disclosure provides an example of a main chamber 10 housing an electron beam inspection system, it should be noted that the various aspects of the present disclosure in its broadest sense are not limited to a chamber housing an electron beam inspection system. Rather, it should be understood that the aforementioned principles may also be applied to other chambers.

[0070] Now refer to Figure 2 , Figure 2 A schematic diagram consistent with an embodiment of the present disclosure is shown, which illustrates a Figure 1 The exemplary electron beam tool 40 of the exemplary charged particle beam inspection system 100 is shown in FIG. The electron beam tool 40 (also referred to herein as the device 40) includes an electron source 101, a gun hole plate 171 having a gun hole 103, a condenser lens 110, a source conversion unit 120, a primary projection optical system 130, a sample stage (not shown in FIG. 1 ), and a sample stage 130. Figure 2 ), a secondary optical system 150 and an electronic detection device 140. The primary projection optical system 130 may include an objective lens 131. The electronic detection device 140 may include a plurality of detection elements 140_1, 140_2 and 140_3. The beam splitter 160 and the deflection scanning unit 132 may be placed inside the primary projection optical system 130. It is understood that other known components of the device 40 may be appropriately added / omitted.

[0071] The electron source 101, the aperture plate 171, the condenser lens 110, the source conversion unit 120, the beam splitter 160, the deflection scanning unit 132 and the primary projection optical system 130 may be aligned with the primary optical axis 100_1 of the device 100. The secondary optical system 150 and the electron detection device 140 may be aligned with the secondary optical axis 150_1 of the device 40.

[0072] The electron source 101 may include a cathode, an extractor, or an anode, where primary electrons may be emitted from the cathode and extracted or accelerated to form a primary electron beam 102 that forms a cross (virtual or real) 101s. The primary electron beam 102 may be visualized as being emitted from the cross 101s.

[0073] The source conversion unit 120 may include an array of image forming elements (not shown). Figure 2), an aberration compensator array (not shown), a beam limiting aperture array (not shown) and a pre-bent micro-polarizer array (not shown). The image forming element array may include a plurality of micro-polarizers or micro-lenses to form a plurality of parallel images (virtual or real) of the cross 101s with the plurality of sub-beams of the primary electron beam 102. Figure 2 Three sub-bundles 102_1 , 102_2 , and 102_3 are shown as an example, and it should be understood that the source conversion unit 120 can process any number of sub-bundles.

[0074] The condenser lens 110 is configured to focus the primary electron beam 102. The current of the sub-beams 102_1, 102_2 and 102_3 downstream of the source conversion unit 102 can be changed by adjusting the focusing power of the condenser lens 110 or by changing the radial size of the corresponding beam limiting holes in the beam limiting hole array. The current can be changed by changing the radial size of the beam limiting holes and the focusing power of the condenser lens 110. The condenser lens 110 can be an adjustable condenser lens, which can be configured so that the position of its first principal plane is movable. The adjustable condenser lens can be configured to be magnetic, which may cause the off-axis sub-beams 102_2 and 102_3 to illuminate the source conversion unit 120 at a rotation angle. The rotation angle can change with the focusing power or position of the first principal plane of the adjustable condenser lens. Therefore, the condenser lens 110 can be an anti-rotation condenser lens, which can be configured to keep the rotation angle unchanged while the focusing power of the condenser lens 110 is changed. In some embodiments, the condenser lens 110 may be an adjustable anti-rotation condenser lens, wherein the rotation angle is not changed when the focusing power and position of the first principal plane of the condenser lens 110 are changed.

[0075] The objective lens 131 can be configured to focus the sub-beams 102_1, 102_2, and 102_3 onto the sample 190 for inspection, and can form three detection spots 102_1s, 102_2s, and 102_3s on the surface of the sample 190. The aperture plate 171 can block the peripheral electrons of the unused primary electron beam 102 to reduce the Coulomb interaction effect. The Coulomb interaction effect can enlarge the size of each of the detection spots 102_1s, 102_2s, and 102_3s, thereby reducing the inspection resolution.

[0076] The beam splitter 160 may be a Wien filter type beam splitter that includes generating an electrostatic dipole field E1 and a magnetic dipole field B1 (neither of which is present in the Figure 21 and 102_3). If they are applied, the force exerted on the electrons of the sub-beams 102_1, 102_2, and 102_3 by the electrostatic dipole field E1 is equal in amplitude and opposite in direction to the force exerted on the electrons by the magnetic dipole field B1. Therefore, the sub-beams 102_1, 102_2, and 102_3 can pass directly through the beam splitter 160 with a zero deflection angle.

[0077] The deflection scanning unit 132 may deflect the beamlets 102_1, 102_2, and 102_3 to scan the detection spots 102_1s, 102_2s, and 102_3s over three small scanning areas in a section of the surface of the sample 190. In response to the incidence of the beamlets 102_1, 102_2, and 102_3 at the detection spots 102_1s, 102_2s, and 102_3s, three secondary electron beams 102_1se, 102_2se, and 102_3se may be emitted from the sample 190. Each of the secondary electron beams 102_1se, 102_2se, and 102_3se may include electrons having an energy distribution including secondary electrons (energy ≤ 50 eV) and backscattered electrons (energy between 50 eV and the landing energy of the beamlets 102_1, 102_2, and 102_3). The beam splitter 160 may direct the secondary electron beams 102_1se, 102_2se, and 102_3se to the secondary optical system 150. The secondary optical system 150 may focus the secondary electron beams 102_1se, 102_2se, and 102_3se onto the detection elements 140_1, 140_2, and 140_3 of the electron detection device 140. The detection elements 140_1, 140_2, and 140_3 may detect the corresponding secondary electron beams 102_1se, 102_2se, and 102_3se, and generate corresponding signals for constructing an image of a corresponding scan area of ​​the sample 190.

[0078] In some embodiments, the controller 50 may include an image processing system including an image acquisition device (not shown) and storage (not shown). The image acquisition device may include one or more processors. For example, the image acquisition device may include a computer, a server, a mainframe, a terminal, a personal computer, any kind of mobile computing device, or the like, or a combination thereof. The image acquisition device may be communicatively coupled to the electronic detection device 140 of the device 40 through a medium such as an electrical conductor, a fiber optic cable, a portable storage medium, IR, Bluetooth, the Internet, a wireless network, radio, or the like, or a combination thereof. In some embodiments, the image acquisition device may receive a signal from the electronic detection device 140 and may construct an image. The image acquisition device may thus acquire an image of the sample 190. The image acquisition device may also perform various post-processing functions, such as generating contours, superimposing indicators on the acquired image, and the like. The image acquisition device may be configured to perform adjustments to the brightness and contrast of the acquired image, and the like. In some embodiments, the storage may be a storage medium such as a hard disk, a flash drive, a cloud storage, a random access memory (RAM), other types of computer-readable memory, and the like. The storage device may be coupled to the image acquisition device and may be used to save the scanned raw image data as an initial image and a post-processed image.

[0079] In some embodiments, the image acquirer may acquire one or more images of the sample based on an imaging signal received from the electronic detection device 140. The imaging signal may correspond to a scanning operation for performing charged particle imaging. The acquired image may be a single image including multiple imaging regions. The single image may be stored in storage. The single image may be an original image that may be divided into multiple regions. Each of the regions may include an imaging region containing features of the sample 190. The acquired image may include multiple images of a single imaging region of the sample 190 sampled multiple times in a time series. Multiple images may be stored in storage. In some embodiments, the controller 50 may be configured to perform an image processing step on multiple images of the same position of the sample 190.

[0080] In some embodiments, the controller 50 may include a measurement circuit (e.g., an analog-to-digital converter) to obtain a distribution of detected secondary electrons. The electron distribution data collected during the detection time window combined with the corresponding scan path data of each of the primary beamlets 102_1, 102_2, and 102_3 incident on the wafer surface can be used to reconstruct an image of the inspected wafer structure. The reconstructed image can be used to reveal various features of the internal or external structure of the sample 190, and can therefore be used to reveal any defects that may be present in the wafer.

[0081] In some embodiments, the controller 50 may control a motorized stage (not shown) to move the sample 190 during inspection. In some embodiments, the controller 50 may enable the motorized stage to continuously move the sample 190 in one direction at a constant speed. In other embodiments, the controller 50 may enable the motorized stage to change the movement speed of the sample 190 over time depending on the steps of the scanning process. In some embodiments, the controller 50 may adjust the configuration of the primary projection system 130 or the secondary projection system 150 based on the images of the secondary electron beams 102_1se, 102_2se, and 102_3se.

[0082] Although Figure 2 The electron beam tool 40 is shown using three primary electron beams, but it should be understood that the electron beam tool 40 can use two or more numbers of primary electron beams. The present disclosure does not limit the number of primary electron beams used in the apparatus 40.

[0083] Now refer to Figure 3 , Figure 3 is a schematic diagram of a multi-beam device 300 consistent with an embodiment of the present disclosure, which illustrates an exemplary configuration of the adjustable focusing lens 110. It should be understood that the multi-beam device 300 can be a charged particle beam inspection system (e.g. Figure 1 Part of an electron beam inspection system 100).

[0084] The multi-beam device 300 may include an electron source 101, a pre-beamlet forming aperture mechanism 172, a condenser lens 110, an objective lens 131, and a source conversion unit 120 including a beam limiting aperture array 121 and an image forming element array 122. In some embodiments, the electron source 101 may be configured to emit primary electrons and form a primary electron beam 102. In some embodiments, a gun aperture plate (not shown) may be configured to block peripheral electrons of the primary electron beam 102 to reduce the Coulomb effect. In some embodiments, the pre-beamlet forming aperture mechanism 172 further cuts peripheral electrons of the primary electron beam 102 to reduce the Coulomb effect. The primary electron beam 102 may be trimmed into three primary electron beamlets 102_1, 102_2, and 102_3 (or any other number of beamlets) after passing through the pre-beamlet forming aperture mechanism 172. The electron source 101, the gun aperture plate 171, the pre-beamlet forming aperture mechanism 172, and the condenser lens 110 may be aligned with the primary optical axis 100_1 of the multi-beam electron beam tool 300.

[0085] In some embodiments, the source conversion unit 120 may be provided with a beam limiting aperture array 121 and an image forming element array 122. The beam limiting aperture array 121 may include beam limiting apertures 121_1, 121_2, and 121_3. Figure 3Only three holes are shown, but it should be understood that any number of holes can be used as appropriate. The beam limiting holes 121_1, 121_2 and 121_3 can limit the size of the sub-beams 102_1, 102_2 and 102_3 of the primary electron beam 102. The image forming element array 122 may include image forming deflectors 122_1, 122_2 and 122_2. The deflectors 122_1, 122_2 and 122_3 may be configured to deflect the sub-beams 102_1, 102_2 and 102_3 by changing the angle toward the primary optical axis 100_1. In some embodiments, the deflectors further away from the primary optical axis 100_1 can deflect the sub-beams to a greater extent. In addition, the image forming element array 122 may include multiple layers (not shown), and the deflectors 122_1, 122_2 and 122_3 may be arranged in separate layers. Deflectors 122_1, 122_2, and 122_3 may be individually controlled independently of one another. In some embodiments, the deflectors may be controlled to adjust the spacing of the detection spots (e.g., 102_1S, 102_2S, and 102_3S) formed on the surface of the sample 190. As mentioned herein, the spacing of the detection spots may be defined as the distance between two adjacent detection spots on the surface of the sample 190.

[0086] The centrally located deflector of the image forming element array 122 may be aligned with the primary optical axis 100_1 of the multi-beam device 300. Thus, in some embodiments, the central deflector may be configured to maintain the trajectory of the sub-beam 102_1 straight. In some embodiments, the central deflector may be omitted. However, in some embodiments, the primary electron source 101 may not necessarily be aligned with the center of the source conversion unit 120. Furthermore, it should be understood that although Figure 3 A side view of the device 300 is shown, where the beamlet 102_1 is on the primary optical axis 100_1, and when viewed from different sides, the beamlet 102_1 may deviate from the primary optical axis 100_1. That is, in some embodiments, all beamlets 102_1, 102_2, and 102_3 may be off-axis. The off-axis component may be offset relative to the primary optical axis 100_1.

[0087] The deflection angle of the deflected beamlet can be set based on one or more criteria. Figure 3As shown, the deflectors 122_2 and 122_3 can deflect the off-axis beamlets radially outward or away (not shown) from the primary optical axis 100_1. In some embodiments, the deflectors 122_2 and 122_3 can deflect the off-axis beamlets radially inward or toward the primary optical axis 100_1. The deflection angle of the beamlets can be set so that the beamlets 102_1, 102_2 and 102_3 land vertically on the sample 190. The off-axis aberration of the image caused by the lens (such as the objective lens 131) can be reduced by adjusting the path of the beamlets passing through the lens. Therefore, the deflection angle of the off-axis beamlets 102_2 and 102_3 generated by the deflectors 122_2 and 122_3 can be set so that the detection spots 102_2S and 102_3S have small aberrations. The beamlets may be deflected so as to pass through or approach the front focus of the objective lens 131 to reduce aberrations of off-axis detection spots 102_2S and 102_3S. In some embodiments, the deflector may be arranged to land the beamlets 102_1, 102_2 and 102_3 perpendicularly on the sample 1, while the detection spots 102_1S, 102_2S and 102_3S have small aberrations.

[0088] The pre-beamlet forming hole mechanism 172 may include a Coulomb hole array. The central hole (also referred to herein as the on-axis hole) of the pre-beamlet forming mechanism 172 and the central deflector of the source conversion unit 120 may be aligned with the primary optical axis 100_1 of the multi-beam device 300. The pre-beamlet forming mechanism 172 may be provided with a plurality of pre-trimmed holes (e.g., a Coulomb hole array) 172_1, 172_2, and 172_3. The central hole 172_1 of the pre-beamlet forming mechanism 172 may be aligned with the primary optical axis 100_1 and may be disposed above the focusing lens 110 and close to the electron source 101. Figure 3 , three sub-beams 102_1, 102_2, and 102_3 are generated when the primary electron beam 102 passes through the three pre-trimmed holes, and most of the remaining part of the primary electron beam 102 is cut off. That is, the pre-beamlet forming mechanism 172 can trim most of the electrons from the primary electron beam 102 that do not form the three sub-beams 102_1, 102_2, and 102_3. The pre-beamlet forming mechanism 172 can cut off the electrons that will not be used to form the detection spots 102_1S, 102_2S, and 102_3S before the primary electron beam 102 enters the source conversion unit 120. In this way, the Coulomb effect on the beam limiting hole array 121 can be reduced to a large extent. As used in the present disclosure, "pre-beamlet" refers to a primary beamlet having an intermediate beam current value before entering the beam limiting hole. In some embodiments, a gun aperture plate (not shown) may be disposed near the electron source 101 to cut off electrons at an early stage, while the pre-beamlet forming mechanism 172 may also be configured to further cut off electrons around the plurality of beamlets. Figure 3Three apertures of the pre-beamlet forming mechanism 172 are shown, but it will be appreciated that there may be any number of apertures as appropriate.

[0089] In some embodiments, the pre-beamlet forming mechanism 172 can be placed below the condenser lens 110. Placing the pre-beamlet forming mechanism 172 closer to the electron source 101 can more effectively reduce the Coulomb effect. In some embodiments, the aperture plate can be omitted when the pre-beamlet forming mechanism 172 can be close enough to the source 101 while still being manufactured. In some embodiments, the pre-beamlet forming mechanism 172 can be placed along a plane 172P perpendicular to the primary optical axis 100_1.

[0090] The condenser lens 110 may be configured to be adjustable for adjusting the current of the sub-beams 102_1, 102_2 and 102_3. The adjustable condenser lens 110 may have a main plane 110_2 perpendicular to the primary optical axis 100_1, such as Figure 3 As shown. The main plane 110_2 can be moved along the primary optical axis 100_1 of the multi-beam device 300. For example, the main plane 110_2 can be moved further away from the electron source 101 to reduce the current of the sub-beams 102_1, 102_2 and 102_3, and the main plane 110_2 can be moved closer to the electron source 101 to increase the current of the sub-beams 102_1, 102_2 and 102_3. Additionally, the current of the sub-beams 102_1, 102_2 and 102_3 can be changed by changing the size of the beam limiting apertures 121_1, 121_2 and 121_3 of the beam limiting aperture array 121.

[0091] Now refer to FIG. 4A to FIG. 4C , FIG. 4A to FIG. 4C Schematic diagrams of exemplary charged particle beam profiles (e.g., profiles of electron beams) for different probe currents projected onto plane 172P consistent with embodiments of the present disclosure are illustrated. Beam profiles (e.g., PC1, PC2, and PC3) represent virtual projections of beamlets exiting beam limiting aperture array 121 onto plane 172P. The circles representing beam profiles are to be viewed as a visual aid to the portion of the beamlets that generated the corresponding probe beamlets and the size of the probe beamlets exiting the beam limiting aperture array. Figures 4A to 4C The beam profiles of beamlets 102_1, 102_2 and 102_3 downstream of the beam limiting aperture array 121 in a configuration including an adjustable anti-rotation electrostatic condenser lens are illustrated, wherein the rotation angle does not change when the focusing power and position of the principal plane 110_2 of the condenser lens 110 are changed. It should be understood that the beam profile on the plane 172P of the pre-beamlet forming mechanism 172 is a virtual projection shown for illustrative purposes only.

[0092] Figure 4AThe beam profile of the beamlets 102_1, 102_2, and 102_3 with high beam current as projected onto the plane 172P is illustrated, denoted as probe current 3 (PC3). The electrons constituting the beam profile PC3 may identify the portion of the electrons of each of the beamlets 102_1, 102_2, and 102_3 that pass through the corresponding aperture of the beam limiting aperture array 121, while the remaining electrons of the beamlets 102_1, 102_2, and 102_3 may be blocked by the beam limiting aperture array 121. The current of the beamlets passing through the apertures of the pre-beamlet forming mechanism 172 may be based on, for example, the position of the main plane 110_2 of the condenser lens 110 along the primary optical axis 100_1 and the size of the corresponding aperture of the beam limiting aperture array 121. For example, with respect to Figure 4A In the beam profile shown, the principal plane 110_2 of the condenser lens 110 may be closer to the electron source 101 and below the pre-beamlet forming mechanism 172, so that the beam currents of the on-axis beamlet 102_1 and the off-axis beamlets 102_2 and 102_3 downstream of the beam limiting aperture array 121 may be high. The dashed circles representing PC1 and PC2 are only for comparative illustration purposes.

[0093] Figure 4B The beam profile of the beamlets 102_1, 102_2, and 102_3 with a medium beam current projected on the plane 172P is illustrated, which is represented as the detection current 2 (PC2). The electrons constituting the beam profile PC2 may identify the portion of the electrons of each of the beamlets 102_1, 102_2, and 102_3 that pass through the corresponding aperture of the beam limiting aperture array 121, while the remaining electrons of the beamlets 102_1, 102_2, and 102_3 may be blocked by the beam limiting aperture array 121. The current of the beamlets passing through the apertures of the pre-beamlet forming mechanism 172 may be based on, for example, the position of the main plane 110_2 of the condenser lens 110 along the primary optical axis 100_1 and the size of the corresponding aperture of the beam limiting aperture array 121. For example, with respect to Figure 4B In the beamlet profile shown, the principal plane 110_2 of the condenser lens 110 is closer to the center of the distance between the pre-beamlet forming mechanism 172 and the beam limiting aperture array 121, resulting in a moderate beam current for the on-axis beamlet 102_1 and the off-axis beamlets 102_2 and 102_3 leaving the beam limiting aperture array 121. In some embodiments, the position of the beamlet profile PC2 may shift along an axis (e.g., the x-axis) when the beam current changes due to a change in the focal power of the condenser lens 110. In some embodiments, the position of the beamlet profile PC2 may change in multiple axes, such as the x-axis and the y-axis.

[0094] Figure 4CThe beam profile of the beamlets 102_1, 102_2, and 102_3 with low beam current projected on the plane 172P is illustrated, which is represented as the detection current 1 (PC1). The electrons constituting the beam profile PC1 may identify the portion of the electrons of each of the beamlets 102_1, 102_2, and 102_3 that pass through the corresponding aperture of the beam limiting aperture array 121, while the remaining electrons of the beamlets 102_1, 102_2, and 102_3 may be blocked by the beam limiting aperture array 121. The current of the beamlets passing through the apertures of the pre-beamlet forming mechanism 172 may be based on, for example, the position of the main plane 110_2 of the condenser lens 110 along the primary optical axis 100_1 and the size of the corresponding aperture of the beam limiting aperture array 121. For example, with respect to Figure 4C In the beamlet distribution shown, the main plane 110_2 of the condenser lens 110 is between the pre-beamlet forming mechanism 172 and the beam limiting aperture array, but closer to the beam limiting aperture array 121, resulting in low beam currents for the on-axis beamlet 102_1 and the off-axis beamlets 102_2 and 102_3 leaving the beam limiting aperture array 121. It should be understood that as the beam current changes, the position of the beamlet distribution PC1 can shift along an axis (e.g., the x-axis). In some embodiments, the position of the beamlet distribution PC1 can change on multiple axes, such as the x-axis and the y-axis.

[0095] Now refer to Figures 5A to 5C , which illustrates a schematic diagram of exemplary charged particle beam distributions (eg, distributions of an electron beam) for different probe currents projected onto a plane 172P consistent with an embodiment of the present disclosure. Figures 5A to 5C The projected beam profiles of beamlets 102_1, 102_2 and 102_3 leaving the beam-limiting aperture array 121 in a configuration including an adjustable electromagnetic condenser lens are illustrated, which can cause the off-axis beamlets 102_2 and 102_3 to illuminate the beam-limiting aperture array 121 at a rotation angle. The rotation angle can vary with the focusing power or the position of the principal plane 110_2 of the adjustable condenser lens 110 along the primary optical axis 100_1. The projected beam profile on the plane 172P of the pre-beamlet forming mechanism 172 is a virtual projection shown for illustrative purposes only.

[0096] FIG. 5A to FIG. 5C The distribution of beamlets 102_1, 102_2 and 102_3 with different beam currents, denoted PC1, PC2 and PC3, is shown. The current of the beamlets passing through the apertures of the pre-beamlet forming mechanism 172 may be based on, for example, the position of the principal plane 110_2 of the condenser lens 110 along the primary optical axis 100_1 and the size of the corresponding apertures of the beam limiting aperture array 121.

[0097] In the Figure 5A The beamlet distribution PC3 is respectively Figure 5B and Figure 5CWhen comparing the beamlet distribution PC2 and PC1, the beamlet distribution PC3 appears larger based on the relative positioning of the condenser lens 110, the electron source 101, and the pre-beamlet forming mechanism 172. For example, when the principal plane 110_2 of the condenser lens 110 is closer to the electron source 101 and below the pre-beamlet forming mechanism 172, the beamlet distribution PC3 may appear larger than when the principal plane 110_2 of the condenser lens 110 is farther away from the electron source 101 and closer to the beam limiting aperture array 121.

[0098] Reference Figure 5B , the principal plane 110_2 of the condenser lens 110 may be closer to the center of the distance between the pre-beamlet forming mechanism 172 and the beam limiting aperture array 121, resulting in the on-axis beamlet 102_1 and the off-axis beamlets 102_2 and 102_3 leaving the beam limiting aperture array 121 having a medium beam current. The beam profile with the medium beam current is represented by PC2.

[0099] Reference Figure 5C , the principal plane 110_2 of the condenser lens 110 can be closer to the beam limiting aperture array 121, resulting in smaller beam currents of the on-axis beamlet 102_1 and the off-axis beamlets 102_2 and 102_3 leaving the beam limiting aperture array 121. The projection of the beam with smaller beamlet current is represented by PC1.

[0100] In some embodiments, in a multi-beam device 300 including an electromagnetic compound tunable focusing lens, the position of a beamlet distribution PC1, PC2, or PC3 can be varied along two axes (e.g., an x-axis and a y-axis) so that the position can be tracked along a curved path, such as Figures 5A to 5C As used herein, the position of a beamlet may be referred to as the position of a central axis of the beamlet.

[0101] Now refer to Fig. 6A and Figure 6B , Fig. 6A and Figure 6B FIG. 1 is a schematic diagram illustrating an exemplary arrangement of apertures of a pre-beamlet forming mechanism 172 consistent with an embodiment of the present disclosure. Fig. 6A As illustrated, the pre-beamlet forming mechanism 172 may include an on-axis hole 172_1 and off-axis holes such as 172_2 and 172_3. The on-axis hole 172_1 may be configured to generate an on-axis beamlet 102_1 from the primary charged particle beam 102. In some embodiments, the on-axis hole 172_1 may be large enough to allow beamlets of different sizes such as PC1 or PC2 or PC3 to pass through. In some embodiments, the geometric center of the on-axis hole 172_1 may be aligned with the primary optical axis 100_1. The on-axis hole 172_1 may have a circular, elliptical, substantially circular cross-section, or other suitable cross-section.

[0102] The off-axis apertures 172_2 and 172_3 may be configured to generate off-axis beamlets 102_2 and 102_3, respectively. Fig. 6A As shown, off-axis apertures 172_2 and 172_3 can be configured to allow beamlets with high detection current to pass through while maintaining a small overall aperture size to minimize Coulomb effects. For example, one or more off-axis apertures (e.g., apertures 172_2 and 172_3) can be elliptical and taper along the major axis, or be a conical frustum with rounded ends, or other suitable shapes. In some embodiments, the off-axis apertures can be symmetrical or asymmetrical along an axis.

[0103] In some embodiments, the off-axis beamlet 102_2 exiting the pre-beamlet forming mechanism 172 may have a shape substantially similar to the shape of the off-axis aperture 172_2. Based on the position of the condenser lens 110 and the aperture size of the beam-limiting aperture array 121, the distribution of beamlets exiting the aperture of the beam-limiting aperture array 121 may be denoted as PC1, PC2, or PC3. The cross-section of the off-axis beamlets (such as the off-axis beamlets 102_2 and 102_3) exiting the beam-limiting aperture array 121 may be circular or substantially circular.

[0104] In some embodiments, Figure 6B As shown, the pre-beamlet forming mechanism 172 may include an on-axis hole 172_1 and eight off-axis holes, such as 172_2, 172_3, 172_4, 172_5, 172_6, 172_7, 172_8, 172_8 and 172_9, configured to generate nine beamlets from the primary electron beam 102. The off-axis holes may be arranged symmetrically or asymmetrically around the on-axis hole 172_1. The shape, size or cross-section of each off-axis hole may be uniform. In some embodiments, the shape, size or cross-section of the off-axis holes may be non-uniform. Although Figure 6B Nine apertures are shown, but it will be appreciated that there may be any number of apertures and corresponding beamlets as desired.

[0105] Now refer to Fig. 7A and Figure 7B , which illustrates a schematic diagram of an exemplary arrangement of holes of the pre-beamlet forming mechanism 172 consistent with an embodiment of the present disclosure. In some embodiments, as Fig. 7AAs illustrated, the pre-beamlet forming mechanism 172 may include an on-axis hole 172_1 and off-axis holes such as 172_2C and 172_3C. The off-axis holes (e.g., 172_2C and 172_3C) may be curved ellipses and may gradually narrow as the holes approach the origin of the xy coordinates, where the primary optical axis 100_1 passes through the xy plane substantially at the origin. In some embodiments, the orientation of the off-axis holes 172_2C and 172_3C may be based on the rotation angle of the beamlets when passing through the electromagnetic condenser lens and the position of the holes of the beam limiting aperture array 121. In some embodiments, the rotation of the beamlets may vary based on the electrical excitation of the condenser lens.

[0106] In some embodiments, Figure 7B As illustrated, the pre-beamlet forming mechanism 172 may include an on-axis hole 172_1 and eight off-axis holes, such as holes 172_2C, 172_3C, 172_4C, 172_5C, 172_6C, 172_7C, 172_8C, and 172_9C, configured to generate nine beamlets from the primary electron beam 102. The off-axis holes may be arranged so that there is no overlap between adjacent holes. In some embodiments, the shape, size, orientation, or cross-section of the off-axis holes may be uniform. In some embodiments, the shape, size, orientation, or cross-section of the holes may be non-uniform.

[0107] In some embodiments, the Coulomb effect in the region between the pre-beamlet forming mechanism 172 and the beam-limiting aperture array 121 may depend on the size of the beamlets generated by the apertures of the pre-beamlet forming mechanism 172. For example, with respect to on-axis beamlets (e.g. Fig. 6A Compared with 102_1), off-axis beamlets (e.g. Fig. 6A 102_2 and 102_3) may have a larger Coulomb effect because non-circular off-axis holes (e.g. Fig. 6A 172_2 or 172_3) is greater than the overall area of ​​the circular on-axis hole 172_1. The difference in Coulomb effect between the on-axis and off-axis beamlets may result in a difference in resolution within the image. For example, the image area corresponding to the detection spot formed by the off-axis beamlets 102_2 and 102_3 may have a poorer resolution than the image area corresponding to the detection spot formed by the on-axis beamlet 102_1. The difference in resolution within the image may be undesirable because it may affect the user's ability to reliably analyze and detect defects.

[0108] Now refer to Fig. 8A and Figure 8B , which illustrates a schematic diagram of an exemplary arrangement of apertures of a pre-beamlet forming mechanism 172 in a multi-beam device 300 consistent with an embodiment of the present disclosure. Fig. 8A The arrangement of three apertures in a multi-beam device 300 is shown, including an adjustable anti-rotation electrostatic focusing lens (e.g. Figure 3 condenser lens 110), wherein when the focusing power and position of the main plane 110_2 of the condenser lens 110 are changed, the rotation angle does not change. Figure 8B The arrangement of three apertures in a multi-beam device 300 including an adjustable electromagnetic condenser lens is shown, which can cause off-axis beamlets 102_2 and 102_3 to illuminate the beam-limiting aperture array 121 at a rotation angle. The rotation angle can vary with the focusing power or the main plane of the adjustable condenser lens 110 (e.g. Figure 3 The position of the main plane 110_2) along the primary optical axis 100_1 changes.

[0109] like Fig. 8A and Figure 8B As shown, the size of the on-axis hole 172_1 can be enlarged so that the difference in the overall area of ​​the on-axis hole 172_1 and the off-axis holes (eg, 172_2 and 172_3) is reduced, thereby making the detection spots (eg, Figure 3 The resolution differences within the images generated by the detection spots 102_1S, 102_2S and 102_3S) are minimized. Fig. 8A and Figure 8B A circular on-axis hole 172_1 is shown, and other cross-sections including but not limited to elliptical, polygonal, triangular, or any non-circular cross-sections may be used. In some embodiments, the shape and size of the on-axis hole 172_1 may be similar to the off-axis hole (e.g. Fig. 8A The off-axis hole 172_2 or Figure 8B off-axis hole 172_2C).

[0110] Now refer to Fig. 9 , Fig. 9 An exemplary arrangement of apertures in the beam-limiting aperture array 121 is illustrated consistent with an embodiment of the present disclosure. Fig. 9 Nine holes are illustrated, but the beam-limiting aperture array 121 may include any number of holes. In some embodiments, the beam-limiting aperture array 121 may include holes arranged in a regular manner, such as a pattern having a rectangular, circular, spiral, polygonal shape, etc. In some embodiments, the holes of the beam-limiting aperture array 121 may be uniform in shape, size, cross-section, or spacing, or any combination thereof. As used herein, the spacing of an array having circular holes may be referred to as the distance between the centers of two immediately adjacent holes. In some embodiments, the holes of the beam-limiting aperture array 121 may be randomly arranged and may be non-uniform in shape, size, cross-section, or spacing, or any combination thereof.

[0111] In some embodiments, the number of apertures of the beam-limiting aperture array 121 may determine the number of beamlets that are incident on the sample surface and generate detection spots. In some embodiments, the number of apertures in the beam-limiting aperture array 121 may be equal to, less than, or more than the number of apertures of the pre-beamlet forming mechanism 172.

[0112] In some embodiments, the beam limiting aperture array 121 may be located below the focusing lens 110, such as Figure 3 The condenser lens 110 may be configured to collimate the sub-beams 102_1, 102_2, and 102_3 so that they are substantially parallel to the primary optical axis 100_1 and perpendicularly incident on the beam limiting aperture array 121. In some embodiments, the condenser lens 110 may collimate the sub-beams 102_1, 102_2, and 102_3. Figure 7B The apertures 172_1 to 172_9 of the pre-beamlet forming mechanism 172 generate beamlets so that the beamlets are substantially parallel to the primary optical axis 100_1 and are perpendicularly incident on the Fig. 9 The size of the apertures of the beam-limiting aperture array 121 may determine the size of the beamlets leaving the source conversion unit 120 and ultimately determine the size of the detection spot generated on the surface of the sample 190 .

[0113] Now refer to Fig.10 , Fig.10 An exemplary outline of the apertures of the pre-beamlet forming mechanism 172 in a multi-beam device 300 including an electromagnetic compound condenser lens and a beam-limiting aperture array 121 consistent with an embodiment of the present disclosure is illustrated. In some embodiments, the spacing of the apertures of the beam-limiting aperture array 121 may be so small that the corresponding off-axis apertures of the pre-beamlet forming mechanism 172 may include partially overlapping regions 1010_1, 1010_2, 1010_3, and 1010_4, such as Fig.10 For example, off-axis holes 1072_3 and 1072_9 may include overlapping area 1010_1, off-axis holes 1072_5 and 1072_8 may include overlapping area 1010_2, off-axis holes 1072_2 and 1072_7 may include overlapping area 1010_3, and off-axis holes 1072_4 and 1072_6 may include overlapping area 1010_4. In some embodiments, the shape and size of the overlapping area may be uniform, or the shape and size may be non-uniform.

[0114] In some embodiments, the overlap of the aperture distribution of the pre-beamlet forming mechanism 172 may be caused due to the large variation of the detection current based on the combination of the position of the condenser lens 110 and the aperture size of the beam-limiting aperture array 121. For example, if the condenser lens is positioned closer to the beam-limiting aperture array 121 including apertures with a small pitch, the corresponding apertures of the pre-beamlet forming mechanism 172 may partially overlap (e.g., overlap region 1010_1).

[0115] Now refer to Fig.11A , Fig.11A An exemplary arrangement of partially overlapping apertures of a pre-beamlet forming mechanism 172 consistent with embodiments of the present disclosure is illustrated. Fig.11A The pre-beamlet forming mechanism 172 may include an on-axis hole 1172_1 and four off-axis merging holes 1101C, 1102C, 1103C, and 1104C. In some embodiments, the pre-beamlet forming mechanism 172 may include an on-axis hole 1172_1 and four off-axis merging holes 1101C, 1102C, 1103C, and 1 Fig.10 The holes of the pre-beamlet forming mechanism 172 in the overlapping region 1010 can be merged to form off-axis merged holes 1101C, 1102C, 1103C and 1104C. For example, off-axis holes 1172_3 and 1172_9 can be merged to form off-axis merged hole 1101C, off-axis holes 1172_5 and 1172_8 can be merged to form off-axis merged hole 1102C, off-axis holes 1172_2 and 1172_7 can be merged to form off-axis merged hole 1103C, and off-axis holes 1172_4 and 1172_6 can be merged to form off-axis merged hole 1104C.

[0116] In some embodiments, Fig.11A The size of the on-axis aperture 1172_1 can be adjusted accordingly to reduce the difference between the overall area of ​​the off-axis merging aperture (such as, for example, 1101C) and the on-axis aperture 1172_1, thereby minimizing the resolution difference within the image due to the varying Coulomb effect, as described with respect to Fig. 8A and Figure 8B discussed.

[0117] Now refer to Fig. 11B , Fig. 11B An exemplary arrangement of apertures of a pre-beamlet forming mechanism 172B consistent with embodiments of the present disclosure is illustrated. Fig. 11B The pre-beamlet forming mechanism 172B may include an on-axis hole 1172_1 and at least one off-axis hole set 1105C. Fig. 11B As shown, in some embodiments, the pre-beamlet forming mechanism 172B may include a plurality of off-axis aperture sets 1105C.

[0118] In some embodiments, the pre-beamlet forming mechanism 172B may include a planar structure having a plurality of holes. The planar structure may be made of materials including metals, alloys, composite materials, semiconductors, etc. In some embodiments, the material may be an electrical conductor or coated with a conductive material. The holes of the pre-beamlet forming mechanism 172B may be formed using techniques including, but not limited to, machining, micro-electromechanical systems (MEMS) manufacturing techniques, chemical etching, laser cutting, etc.

[0119] In some embodiments, the pre-beamlet forming mechanism 172B may be aligned such that the geometric center of the on-axis hole 1172_1 coincides with the primary optical axis 100_1. The cross-section of the on-axis hole 1172_1 may be circular or substantially circular. In some embodiments, at least a portion of the on-axis primary beamlet formed by the on-axis hole 1172_1 may be incident on an on-axis hole of the beam-limiting hole array 121. In some embodiments, the size of the on-axis hole 1172_1 may be configured to be larger than or substantially similar to the size of the corresponding on-axis hole of the beam-limiting hole array 121. In some embodiments, the size of the on-axis hole of the beam-limiting hole array 121 may determine the size of the detection beamlet that leaves the beam-limiting hole array 121.

[0120] In a multi-beam SEM, it may be desirable to generate multiple beams with a large current range to allow the tool to be used for low-resolution imaging as well as high-resolution imaging. Although a large and continuous current range can be achieved by increasing the size of the apertures, large apertures may negatively affect the mechanical and structural integrity of the structure (e.g., the aperture array) and increase other issues such as Coulomb interaction effects. It may be desirable to fabricate an aperture array capable of generating multiple beams and a large current range while maintaining mechanical and structural integrity.

[0121] In some embodiments, the pre-beamlet forming mechanism 172B may include an off-axis aperture set 1105C, which includes exemplary off-axis apertures 1105C_1, 1105C_2, 1105C_3, 1105C_4, 1105C_5, and 1105C_6. The apertures in the off-axis aperture set 1105C may generate beamlets with discrete current ranges compared to the continuous current range provided by a large aperture of comparable size. Although the off-axis aperture set 1105C is shown as including six off-axis apertures, it is to be understood that any number of off-axis apertures may be provided as appropriate.

[0122] like Fig. 11B As shown, the pre-beamlet forming mechanism 172B can be used in a device configured to generate a 5x5 detection beamlet array. In some embodiments, each off-axis hole set 1105C and the on-axis hole 1172_1 can be connected to Figure 3 The number of off-axis aperture sets 1105C of the pre-beamlet forming mechanism 172B and the on-axis apertures may be associated with the corresponding apertures of the beam-limiting aperture array 121. For example, based on the association, the number of off-axis aperture sets of the pre-beamlet forming mechanism 172B may be equal to the number of off-axis apertures of the beam-limiting aperture array 121. The number of detection beamlets to be generated and the number of apertures (including the off-axis aperture sets 1105C of the pre-beamlet forming mechanism 172B and the on-axis apertures) may be determined based on the application and the number of discrete current settings desired. For example, a 7x7 aperture array may be used in applications where a larger current range of detection beamlets is desired, or a 3x3 aperture array may be used in applications or tools with space limitations.

[0123] Multi-beam devices (e.g. Figure 1 The pre-beamlet forming mechanism 172B in the EBI system 100) can have some or all of the advantages discussed in this article, etc.

[0124] i. Large beam current range - A wide range of beam currents may be desired to perform a variety of operations or functions by a multi-beam SEM. The range of beam currents can be extended by providing various sizes of apertures within the off-axis aperture set, such as Fig. 11B As shown, the Coulomb interaction effects are simultaneously reduced.

[0125] ii. Enhanced Structural Integrity - The holes within the off-axis hole set can be separated by the material of the pre-beamlet forming mechanism 172B, thereby maintaining the mechanical rigidity of the structure while increasing the beam current range used to examine the sample.

[0126] iii. Reduced Coulomb interaction effects - The Coulomb interaction is a function of the transmission area of ​​the hole array and therefore increases for systems with large holes. The holes in the off-axis hole set are able to generate a wide range of beam currents while reducing the transmission area of ​​the electrons, thereby reducing the Coulomb interaction effects and therefore improving imaging resolution.

[0127] iv. Manufacturability - Fabricating holes in an array of holes such as pre-beamlet forming mechanism 172 may include removing material to form paths for electrons to travel through. While larger holes increase the continuous current range, they may negatively impact the manufacturability of the array due to insufficient support material remaining after the holes are formed. Pre-beamlet forming mechanism 172B can be easily and reliably manufactured because the holes within the off-axis hole set are separated by the material from which the pre-beamlet forming mechanism 172B is made.

[0128] In some embodiments, the sizes of the off-axis holes in the off-axis hole set 1105C (e.g., 1105C_1, 1105C_2, 1105C_3, 1105C_4, 1105C_5, and 1105C_6) may be different. Fig. 11BAs illustrated, the radii of the circular off-axis apertures may be different. For example, the radius of aperture 1105C_1 may be smaller than the radius of 1105C_2, the radius of aperture 1105C_2 may be smaller than the radius of aperture 1105C_3, the radius of aperture 1105C_3 may be smaller than the radius of aperture 1105C_4, the radius of aperture 1105C_4 may be smaller than the radius of aperture 1105C_5, and the radius of aperture 1105C_5 may be smaller than the radius of aperture 1105C_6. In some embodiments, the size of at least two off-axis apertures in the off-axis aperture set may be different. The size of the off-axis aperture may determine the current of the primary beamlet generated from the off-axis aperture, and apertures of different sizes may allow beamlets with a larger current range to be generated. In some embodiments, the off-axis apertures in the off-axis aperture set 1105C may be smaller, equal to, or larger than the corresponding off-axis apertures in the beam-limiting aperture array 121.

[0129] In some embodiments, the cross-section of the holes in the off-axis hole set 1105C can be circular, rectangular, substantially circular, elliptical, polygonal, etc. The cross-section of the hole can determine the cross-section and shape of the primary sub-beams generated thereby. In some embodiments, the off-axis hole set 1105C can include holes with different cross-sections. For example, holes 1105C_1 and 1105C_3 can be circular, and holes 1105C_2 and 1105C_4 can be elliptical.

[0130] In some embodiments, the spacing of the holes in the off-axis hole set 1105C can be uniform. In the context of the present disclosure, and in the case of circular holes, such as Fig. 11B As shown, the spacing can be defined as the shortest distance between the geometric centers of adjacent holes. In some embodiments, the spacing of the holes in the off-axis hole set 1105C can be non-uniform.

[0131] In some embodiments, the holes in the off-axis hole set 1105C can be arranged along a curved path, such as by a virtual path (e.g. Fig. 11B The dashed lines indicating virtual paths 1172_P1 and 1172_P2 are for illustrative purposes only. It should be understood that the radius of curvature of the path along which the holes in the off-axis hole set are arranged can vary between off-axis hole sets. It should also be understood that the off-axis hole set (e.g. Fig. 11B In some embodiments, the holes in the off-axis hole set 1105C can be arranged along multiple paths with different radii of curvature. In some embodiments, the holes in the off-axis hole set 1105C can be arranged along a straight path. In some embodiments, the path along which the holes in the off-axis hole set 1105C are arranged can be based on the characteristics of the condenser lens 110.

[0132] In some embodiments, an off-axis hole set may intersect with an adjacent off-axis hole set such that a hole may correspond to more than one off-axis hole set. For example, hole 1105C_8 may correspond to an off-axis hole set along path 1172_P1 and an off-axis hole set along path 1172_P2. In some embodiments, an off-axis hole set may intersect with one or more off-axis hole sets. In some embodiments, a hole in an off-axis hole set may be placed adjacent to a hole in an intersecting off-axis hole set such that at least portions of the holes overlap each other.

[0133] It should be noted that the curved ellipse and tapered ellipse 1172_V indicating the boundaries within which the holes in the off-axis hole set 1105C may be disposed are visual aids for illustrative purposes only.

[0134] In some embodiments, each hole in the off-axis hole set 1105C can generate a primary beamlet that is incident on a condenser lens 110 that is disposed downstream of the pre-beamlet forming mechanism 172B. In some embodiments, the condenser lens 110 can include an adjustable electromagnetic lens configured to cause the primary beamlet to form a corresponding detection beamlet from a plurality of detection beamlets that leave the beam-limiting hole array 121. Based on the arrangement of the condenser lens 110, the primary beamlets formed by the holes in the off-axis hole set 1105C can be incident on the corresponding holes of the beam-limiting hole array 121 at a rotation angle. The rotation angle can vary with the focusing power or the position of the principal plane 110_2 of the adjustable condenser lens 110 along the primary optical axis 100_1. For example, if the condenser lens 110 is positioned closer to the electron source 101, the detection beamlet generated from the hole 1105C_6 can be incident on the corresponding off-axis hole of the beam-limiting hole array 121. If the size of the corresponding off-axis hole of the beam-limiting hole array 121 is larger than the size of the hole 1105C_6, then the detection current of the detection beamlet leaving the corresponding hole of the beam-limiting hole array 121 may be determined based on the size of the hole 1105C_6 of the pre-beamlet forming mechanism 172B. Alternatively, if the size of the corresponding off-axis hole of the beam-limiting hole array 121 is smaller than the size of the hole 1105C_6, then the detection current of the detection beamlet leaving the corresponding hole of the beam-limiting hole array 121 may be determined based on the hole size of the beam-limiting hole array 121.

[0135] In some embodiments, the off-axis hole set 1105C may also be referred to as a pre-beamlet forming hole set 1105C. The detection current of the corresponding detection beamlet may be determined based on the characteristics of the holes in the pre-beamlet forming hole set 1105C. Each hole in the pre-beamlet forming hole set 1105C (e.g., holes 1105C_1 to 1105_C6) may be configured to affect the detection current of the detection beamlet. The characteristics of the holes in the pre-beamlet forming hole set 1105C may include, but are not limited to, other arrangement characteristics such as size, shape, or position. The detection current of the detection beamlet may be able to be discretely adjusted based on, for example, the size of the holes in the pre-beamlet forming hole set 1105C that form the primary beamlet.

[0136] In some embodiments, adjusting the position of the condenser lens 110 along the primary optical axis 100_1 can affect or act on the detection current of the detection beamlet formed by the corresponding primary beamlet. As an example, the condenser lens 110 placed in a first position can cause a first portion of the primary electron beam 102 to pass through an aperture in the pre-beamlet forming aperture set 1105C to form a primary beamlet having a beam current value, and the condenser lens 110 placed in a second position different from the first position can cause a second portion of the primary electron beam 102 to pass through a different aperture in the pre-beamlet forming aperture set 1105C to form a different primary beamlet having a different beam current value, thereby affecting the detection current of the detection beamlet formed from the corresponding primary beamlet.

[0137] Now refer to Fig. 11C , Fig. 11C The relationship between the detection spot size and the beam current of a beamlet formed by an aperture in the off-axis aperture set 1105C is illustrated. As illustrated, a large aperture (e.g., aperture 1105C_6) can allow more electrons to pass through, and thus, the formed beamlet can have a larger current value and a larger spot size. A small aperture (e.g., aperture 1105C_6) can allow more electrons to pass through, and thus, the formed beamlet can have a larger current value and a larger spot size. Fig. 11B In some embodiments, the aperture 1105C_1 to 1105C_6 have the same size, and the beamlets formed by the apertures may have different current values ​​for each of the apertures. Further, the current value of a beamlet formed by one aperture may be greater or less than the current value of a beamlet formed by an adjacent aperture along the virtual path.

[0138] Now refer to Fig.11D , Fig.11D 1 illustrates an exemplary arrangement of apertures of a pre-beamlet forming mechanism 172D consistent with an embodiment of the present disclosure. Fig. 11B Compared to the pre-beamlet forming mechanism 172B, the off-axis hole set 1105C may include at least one non-circular hole 1105C_7. Fig.11D As shown, the cross section of hole 1105C_7 can be elliptical. Holes with other cross sections can also be used, including but not limited to tapered ellipse, curved ellipse, polygon, etc.

[0139] In some embodiments, the aperture 1105C_7 of the pre-beamlet forming mechanism 172D can be positioned closer to the primary optical axis 100_1 or the on-axis aperture 1172_1 so that the beam current of the beamlet generated from the aperture 1105C_7 is lower. A larger aperture 1105C_7 can be used to provide a continuous current range while maintaining a low Coulomb interaction effect due to the low beam current. In some embodiments, one or more off-axis aperture sets 1105C can include an aperture 1105C_7.

[0140] In a multi-beam SEM, it may be desirable to generate multiple beams with a large current range to allow the tool to be used for low-resolution imaging as well as high-resolution imaging. Although a large and continuous current range can be achieved by increasing the size of the apertures, large apertures may increase Coulomb interaction effects, among other issues. For high-resolution applications, while smaller apertures may produce smaller detection spots, Coulomb interaction effects may limit the resolution of the images obtained. Therefore, it may be desirable to fabricate an aperture array capable of generating multiple beams over a wide current range while reducing Coulomb interaction effects and improving image resolution.

[0141] One of many ways to mitigate Coulomb interaction effects can include using a pre-beamlet forming mechanism 172B that includes an active aperture array. In the context of the present disclosure, "active aperture" refers to an aperture or aperture assembly that can be configured to be electrically activated so that an electric field is created within the aperture or aperture assembly.

[0142] Now refer to Fig.11E , Fig.11E An expanded view of an exemplary active aperture 1105_C6A is illustrated, which includes a top aperture plate 1120, an active deflector 1130, and a bottom aperture plate 1140. Although the active aperture 1105_C6A is shown as including three elements, it should be understood that there may be more elements, such as spacers, microlenses, as appropriate. In some embodiments, the top aperture plate 1120, the active deflector 1130, and the bottom aperture plate 1140 can be stacked without any spacers disposed between them. In some embodiments, the active aperture 1105_C6A may also be referred to as an active aperture assembly or an active aperture stack. In some embodiments, the active aperture 1105_C6A may not include the top aperture plate 1120, while in other embodiments, the active aperture 1105_C6A may not include the bottom aperture plate 1142.

[0143] In some embodiments, for example Fig. 11BAperture 1105C_6 of pre-beamlet forming mechanism 172B may include an active aperture. In some embodiments, one or more off-axis apertures of pre-beamlet forming mechanism 172B may include an active aperture, or one or more off-axis aperture sets (such as, for example, 1105C) may include an active aperture, or pre-beamlet forming mechanism 172B may include an active aperture array. As used herein, "active aperture array" refers to an active aperture array such as 1105_C6A. It should be understood that the active aperture array may include active apertures of different sizes, cross-sections, shapes, configurations, or materials.

[0144] In some embodiments, the active aperture 1105_C6A may include an active aperture assembly manufactured using techniques including, but not limited to, machining, MEMS manufacturing techniques, chemical etching, laser cutting, micromachining, etc. The pre-beamlet forming mechanism 172B including the active aperture array may be made of conductive, semiconductor, or insulating materials, depending on the application. For example, in some embodiments, the top aperture plate 1120, active deflector 1130, and bottom aperture plate 1140 of the active aperture 1105_C6A may be made using semiconductor materials, and the spacer layer (not in Fig.11E ) can be made using electrically insulating materials.

[0145] In some embodiments, the top aperture plate 1120 can be configured to allow a portion of the electrons of the primary electron beam 102 to pass through based on the desired current setting. The top aperture plate 1120 can include a plurality of off-axis apertures 1122 separated by the material from which the top aperture plate 1120 is made. The off-axis apertures 1122 can include apertures having, but not limited to, circular, elliptical, rectangular, elongated, non-circular, polygonal cross-sections. The off-axis apertures 1122 in the active aperture array of the pre-beamlet forming mechanism 172B can be non-uniform in size, spacing, cross-section, etc.

[0146] In some embodiments, the bottom aperture plate 1140 may include a plurality of off-axis apertures 1142 separated by the material from which the bottom aperture plate 1140 is made. The off-axis apertures 1142 may include apertures having, but not limited to, circular, elliptical, rectangular, elongated, non-circular, polygonal cross-sections. The off-axis apertures 1142 in the active aperture array of the pre-beamlet forming mechanism 172B may be non-uniform in size, spacing, cross-section, etc. In some embodiments, the geometric center of the off-axis aperture 1122 may be aligned with the geometric center of the corresponding off-axis aperture 1142. In some embodiments, the size of the off-axis aperture 1122 and the corresponding off-axis aperture 1142 may be substantially similar.

[0147] In some embodiments, the top aperture plate 1120 or the bottom aperture plate 1140 may be electrically grounded. In the context of the present disclosure, electrical ground refers to a reference point in the active aperture 1105_C6A from which the applied voltage is measured. For example, if the top aperture plate 1120 or the bottom aperture plate 1140 is electrically grounded and a voltage signal of +100V is applied to the active deflector 1130, then the effective voltage applied to the active deflector 1130 is +100V.

[0148] In some embodiments, the active deflector 1130 may include a monopole deflector or a multipole deflector configured to be electrically activated to affect the path of a portion of the electrons of the primary electron beam 102. Fig.11E A bipolar deflector is shown, but the active deflector 1130 may include any number of poles as appropriate. The poles of the active deflector 1130 may be arranged radially along a plane substantially perpendicular to the primary optical axis 100_1 and substantially parallel to the top aperture 1120 or the bottom aperture plate 1140. In some embodiments, the aperture 1132 formed in the active deflector plate 1130 may be larger or equal in size to the off-axis aperture 1122 or 1142.

[0149] Although the holes in the off-axis hole set can generate a wide range of beam currents while reducing the transmission area of ​​the electrons, thereby reducing the Coulomb interaction effect, it may be necessary to further reduce the Coulomb interaction effect for high-resolution applications. In some embodiments, the active hole array can be configured to generate multiple off-axis sub-beams from the primary electron beam 102 while further reducing the Coulomb interaction effect.

[0150] In some embodiments, the active deflector 1130 can be electrically activated by applying an electrical signal to one or more poles based on factors including desired current settings, image resolution, or electron deflection or beamlet size, etc. In some embodiments, the electrical signal can include a voltage signal suitable for deflecting a portion of the electrons of the primary electron beam 102 that exit the off-axis aperture 1122. In some embodiments, based on desired beamlet characteristics, one or more poles of the active deflector 1130 can be electrically grounded, one or more poles of the active deflector 1130 can be electrically activated, or a combination thereof.

[0151] In some embodiments, the bottom aperture plate 1140 may include an aperture 1142 that is aligned with the corresponding off-axis aperture 1132 or the corresponding off-axis aperture 1122. The aperture 1142 may be smaller in size than the aperture 1132 of the active deflection plate 1130. In some embodiments, the aperture 1142 may be configured to block deflected electrons from leaving the aperture 1132, thereby generating a beamlet that includes fewer electrons, thereby reducing Coulomb interaction effects within the generated beamlets.

[0152] In some embodiments, the device 300 may include Fig. 11B The pre-beamlet forming mechanism 172B includes one or more off-axis active aperture sets, such as 1105C, and the device 300 may also include Figure 3 The active aperture 1105_C6A may be configured to generate off-axis primary beamlets (e.g. Figure 2 In some embodiments, for example, the beam limiting aperture 121_2 can be configured to receive the beamlet 102_2 and generate a detection beamlet with an associated beam current from the corresponding primary beamlet. The associated beam current of the detection beamlet can be adjustable based on at least the size of the off-axis aperture 1122 or the electric field between the top aperture plate 1120 and the active deflector 1130, or both.

[0153] In some embodiments, the associated beam current of the probe beamlet may be adjustable over a discrete range. For example, the off-axis active aperture set 1105_CA (not shown, but similar in some embodiments to Fig. 11B 1105_C) may include multiple off-axis active apertures (1105_C1A, 1105_C2A, 1105_C3A, 1105_C4A, 1105_C5A, and 1105_C6A, not shown, but similar to 1105C_1 to 1105C_6 in some embodiments). The size, shape, or cross-section of one or more off-axis active apertures may be different. The size of the off-axis aperture may determine the size of the beam or the number of electrons passing through, thereby allowing the beam current to be adjusted based on the size of the off-axis active aperture through which the beam is directed. It should be understood that the off-axis active aperture set 1105_CA may include fewer or more active apertures as desired.

[0154] In some embodiments, the voltage signal applied to the active deflector 1130 can be fixed or substantially fixed. The electric field formed due to the fixed voltage signal applied to the top aperture plate 1120 and the active deflector 1130 can be fixed or substantially fixed. In this case, the beam current of the probe beamlet can be adjusted based on at least the selected hole size of the off-axis hole 1122. In some embodiments, the selected off-axis hole 1122 can be predetermined or dynamically determined based on factors including but not limited to materials, desired analysis, solution feedback, etc.

[0155] In some embodiments, the voltage signal applied to the active deflector 1130 may be adjustable. The electric field formed due to the adjustable voltage signal applied to the active deflector 1130 may be adjustable. In this case, the beam current of the detection beamlet may be determined based on the electric field between the top aperture plate 1120 and the active deflector 1130. The electric field formed by the difference in the voltage signal applied between the top aperture plate 1120 and the active deflector 1130 may deflect the path of a portion of the charged particles (e.g., electrons) passing through the active aperture 1105_C6A, so that some of the peripheral electrons may be blocked by the bottom aperture plate 1140. Due to the deflection from the electric field and the blocking of the peripheral electrons, the primary beamlet formed may contain fewer electrons, and therefore, the beam current of the corresponding detection beamlet formed may be reduced.

[0156] In some embodiments, the beam current of the detection beamlet can be adjusted by selecting the size of the hole 1122 of the active aperture 1105_C6A, or by adjusting the difference in voltage signals applied to the top aperture plate 1120 and the active deflector 1130 to adjust the electric field in the active aperture 1105_C6A, or by selecting holes of a beam limiting aperture array 121 configured to generate a detection beamlet based on the size of the beamlet allowed to pass through, or a combination thereof.

[0157] Now refer to Fig.11F , Fig.11F FIG. 1 shows a cross-sectional view of an active hole 1105_C6A consistent with an embodiment of the present disclosure. Fig.11F As illustrated, a portion of the primary electron beam 102 may enter the active aperture 1105_C6A through the aperture 1122 of the top aperture plate 1120, and the beamlet 102_AA may exit the active aperture 1105_C6A through the aperture 1142 of the bottom aperture plate 1140. In some embodiments, the active deflector 1130 may be electrically activated to deflect peripheral electrons of the primary electron beam 102 so that they may be blocked by the bottom aperture plate 1140. The deflection of the peripheral electrons may be determined based on the characteristics of the electrical signal applied to the active deflector 1130. The electrical signal may include a voltage signal, and the characteristics of the voltage signal may include polarity or amplitude, etc.

[0158] In some embodiments, the electrical activation of the active deflector 1130 can be dynamically adjusted based on the application, desired analysis, system performance, etc. For example, by adjusting the electrical activation of the active deflector 1130 based on scanning resolution information obtained using a feedback mechanism, the imaging resolution can be adjusted. In some embodiments, the active aperture 1105_C6A can be configured to use circuitry (not shown) to Fig.11E and 11FThe circuit system may include a microprocessor, a sensing circuit, a switch driver circuit, a voltage regulating circuit, a memory, a timing circuit, etc. It should be understood that the circuit system may include other related components as appropriate.

[0159] In some embodiments, deflector poles having active apertures in an active aperture array of substantially similar aperture sizes corresponding to current settings may be electrically grouped. Electrical grouping of deflector poles having active apertures of substantially similar sizes may be desirable because it may limit the number of electrical connections and thus improve system integration, operation, and control.

[0160] Now refer to Fig.12 , Fig.12 1 is a process flow diagram showing an exemplary method 1200 for observing a sample using a multi-beam inspection tool consistent with an embodiment of the present disclosure. For example, the method 1200 may be executed by the controller 50 of the EBI system 100, such as Figure 1 The controller 50 may be programmed to implement one or more steps in the method 1200. For example, the controller 50 may instruct the modules of the charged particle beam device to activate the charged particle source to generate the charged particle beam, and perform other functions.

[0161] In step 1210, a charged particle beam (eg Figure 2 The primary electron beam 102 can be generated by activating a charged particle source (e.g. Figure 2 The electron source 101 may be generated by a primary electron beam formed along the primary optical axis. The electron source may be remotely activated, for example, by using software, an application, or an instruction set for a processor of the controller to power the electron source through the control circuit system. The primary electron beam may be generated by a gun aperture plate (e.g. Figure 2 gun hole plate 171) or hole array (e.g. Figure 2 pre-beamlet forming mechanism 172) or both.

[0162] In step 1220, a plurality of beamlets (eg Figure 3 The sub-beams 102_1, 102_2 and 102_3) can be formed by passing through a pre-beam forming mechanism (e.g. Figure 3 The number of generated beamlets may be based on the number of pre-trimmed holes of the pre-beamlet forming mechanism. For example, for illustrative purposes, three beamlets and three pre-trimmed holes are provided. Figure 3As shown. The beamlets generated after the primary electron beam passes through the pre-beamlet forming mechanism may include an on-axis beamlet and at least one off-axis beamlet. In some embodiments, multiple off-axis beamlets may be generated. The pre-beamlet forming mechanism may include an on-axis hole and at least one off-axis hole. The shape or cross-section of the on-axis hole may be circular or substantially circular. The off-axis hole may be an elongated hole with a rounded end and a gradually narrowing width. In some embodiments, the off-axis hole may be elongated and curved (e.g., such as Figure 7B In some embodiments, one or more of the off-axis holes may involve a first hole that overlaps with a second hole (e.g., Fig.11A In some embodiments, the shape of the off-axis apertures may be based on the paths of the corresponding beamlets associated with the adjustable detection currents of the detection beamlets, the adjustability of the plane of the condenser lens, and the characteristics of the second aperture array.

[0163] In step 1230, a focusing lens (eg Figure 2 The plane of the condenser lens 110) (eg Figure 3 The position of the principal plane 110_2) of the condenser lens can be adjusted along the primary optical axis. In some embodiments, the adjustable plane can be the principal plane of the condenser lens. The position of the principal plane of the condenser lens can be relative to the beam limiting aperture array (e.g. Figure 3 The positions of the beam-limiting aperture array 121 and the pre-beamlet forming mechanism are adjusted to adjust the detection current of the detection beamlets generated by the beam-limiting aperture array. For example, if the principal plane of the condenser lens is closer to the beam-limiting aperture array than the pre-beamlet forming mechanism, the beam currents of the on-axis beamlets and the off-axis beamlets leaving the beam-limiting aperture array can be lower than when the principal plane is closer to the pre-beamlet forming mechanism.

[0164] In some embodiments, in a multi-beam device including an adjustable electromagnetic condenser lens, an off-axis beamlet can illuminate a beam-limiting aperture array at a rotation angle. The rotation angle can vary with the focusing power or the position of the principal plane of the adjustable condenser lens along the primary optical axis. The off-axis beamlet can be rotated by a certain angle so that the off-axis beamlet passes through a corresponding off-axis aperture of the beam-limiting aperture array.

[0165] In some embodiments, adjusting the position of the principal plane of the condenser lens may modify the characteristics of the probe beamlets exiting the array of beam-limiting apertures. The characteristics of the probe beamlets may include, but are not limited to, the probe current of the probe beamlets, the portion of the beamlets from which the probe beamlets may be generated, etc.

[0166] In step 1240, the probe beamlets are passed through a beam limiting aperture array (eg, Figure 3 and 9The beam limiting aperture array 121) is generated from the plurality of beamlets. The characteristics of the detection beamlets may be determined based on the characteristics of the beam limiting aperture array. The characteristics of the beam limiting aperture array may include, but are not limited to, the size, cross-section, shape, spacing, and positioning of the apertures. The characteristics of the detection beamlets may be determined by one or more characteristics of the beam limiting aperture array.

[0167] In some embodiments, the position of the beam-limiting aperture array may be fixed. For example, the beam-limiting aperture array may be arranged in a plane perpendicular to the primary optical axis and at a predetermined distance from the focusing lens or pre-beamlet forming mechanism. In some embodiments, the beam-limiting aperture array may include apertures of uniform shape, size, cross-section, and spacing. In some embodiments, the apertures may also be non-uniform.

[0168] In step 1250, the probe beamlets generated by the beam-limiting aperture array may be focused and directed toward the sample (eg, Figure 2 of the sample 190) to form a detection spot (e.g. Figure 2 In some embodiments, each of the plurality of detection beamlets may form a detection spot on the sample. The detection beamlets may be formed using an objective lens (e.g. Figure 3 The probe sub-beam may be incident perpendicular to the sample surface. The primary electrons of the probe sub-beam incident on the sample may generate secondary electrons. The secondary electrons may be detected using a secondary electron detector or a backscattered electron detector, thereby revealing information about the sample being detected.

[0169] Now refer to Fig.13 , Fig.13 1 is a process flow diagram showing an exemplary method 1300 for observing a sample using a multi-beam inspection tool consistent with an embodiment of the present disclosure. For example, the method 1300 may be executed by the controller 50 of the EBI system 100, such as Figure 1 The controller 50 may be programmed to implement one or more steps in the method 1300. For example, the controller 50 may instruct modules of the charged particle beam device to activate a charged particle source to generate a charged particle beam and perform other functions.

[0170] In step 1310, a charged particle beam (eg Figure 2 The primary electron beam 102 can be generated by activating a charged particle source (e.g. Figure 2 For example, the electron source 101 may be powered to emit light along the primary optical axis (e.g. Figure 2The electron source can be remotely activated, for example, by using software, an application or an instruction set for a processor of a controller to power the electron source through a control circuit system. The primary electron beam can be generated by a gun aperture plate (e.g. Figure 2 gun hole plate 171) or hole array (e.g. Figure 2 pre-beamlet forming mechanism 172) or both.

[0171] In step 1320, a plurality of beamlets (eg Figure 3 The sub-beams 102_1, 102_2 and 102_3) can be formed by passing through a pre-beam forming mechanism (e.g. Fig. 11B The number of primary beamlets generated may be based on the number of holes of the pre-beamlet forming mechanism. For illustrative purposes, three beamlets and three holes are used, for example, in Figure 3 The beamlets generated after the primary electron beam passes through the pre-beamlet forming mechanism may include an on-axis primary beamlet and at least an off-axis primary beamlet. In some embodiments, a plurality of off-axis beamlets may be generated. The pre-beamlet forming mechanism may include an on-axis hole and at least one off-axis hole set (e.g. Fig. 11B The shape or cross-section of the on-axis holes can be circular or substantially circular. The cross-section of the holes in the off-axis hole set can be circular, rectangular, substantially circular, elliptical, polygonal, etc. The cross-section of the hole can determine the cross-section and shape of the primary beamlet generated thereby. The primary beamlet generated by the holes of the pre-beamlet forming mechanism 172B can be incident on a focusing lens (e.g. Figure 2 on the focusing lens 110).

[0172] In step 1330, the plane of the focusing lens (eg Figure 3 The position of the principal plane 110_2) can be adjusted along the primary optical axis. In some embodiments, the focusing lens 110 may include an adjustable electromagnetic lens configured to cause the primary beamlets to form out of the beam limiting aperture array (e.g. Figure 3 and Fig. 9 Based on the setting of the condenser lens 110, the primary beamlets formed by the holes in the off-axis hole set can be incident on the corresponding holes in the beam limiting hole array at a rotation angle. The rotation angle can change with the focusing power or the position of the main plane of the adjustable condenser lens along the primary optical axis. For example, if the condenser lens is positioned closer to the electron source, the primary beamlets from the holes (e.g. Fig. 11B The detection sub-beams generated by 1105C_6) can be incident on the corresponding off-axis holes of the beam limiting hole array.

[0173] In step 1340, a plurality of detection beamlets may be generated from the plurality of primary beamlets by means of a beam-limiting aperture array. On-axis detection beamlets may be associated with corresponding on-axis primary beamlets, and off-axis detection beamlets may be associated with corresponding off-axis aperture sets in pre-beamlet forming mechanism 172B. Characteristics of the formed detection beamlets may be determined based on characteristics of the beam-limiting aperture array. Characteristics of the beam-limiting aperture array may include, but are not limited to, size, cross-section, shape, spacing, positioning of the apertures. Characteristics of the detection beamlets may be determined by one or more characteristics of the beam-limiting aperture array.

[0174] In step 1350, the probe beamlets generated by the beam-limiting aperture array may be focused and directed toward the sample (eg, Figure 2 of the sample 190) to form a detection spot (e.g. Figure 2 In some embodiments, each of the plurality of detection beamlets may form a detection spot on the sample. The detection beamlets may be formed using an objective lens (e.g. Figure 3 The probe sub-beam may be incident perpendicular to the sample surface. The primary electrons of the probe sub-beam incident on the sample may generate secondary electrons. The secondary electrons may be detected using a secondary electron detector or a backscattered electron detector, thereby revealing information about the sample being detected.

[0175] Now refer to Fig.14 , Fig.14 1400 is a process flow diagram showing an exemplary method 1400 for observing a sample using a multi-beam inspection tool consistent with an embodiment of the present disclosure. For example, the method 1400 may be executed by the controller 50 of the EBI system 100, such as Figure 1 The controller 50 may be programmed to implement one or more steps in the method 1400. For example, the controller 50 may instruct the modules of the charged particle beam device to activate the charged particle source to generate the charged particle beam, and also perform other functions.

[0176] In step 1410, a charged particle beam (eg Figure 2 The primary electron beam 102 can be generated by activating a charged particle source (e.g. Figure 2 For example, the electron source 101 may be powered to emit light along the primary optical axis (e.g. Figure 2 The electron source can be remotely activated, for example, by using software, an application or an instruction set for a processor of a controller to power the electron source through a control circuit system. The primary electron beam can be formed by a gun aperture plate (e.g. Figure 2 gun hole plate 171) or hole array (e.g. Figure 2 pre-beamlet forming mechanism 172) or both.

[0177] In step 1420, a plurality of beamlets (eg Figure 3 The sub-beams 102_1, 102_2 and 102_3) can be formed by passing through a pre-beam forming mechanism (e.g. Fig. 11B The number of primary beamlets generated may be based on the number of holes of the pre-beamlet forming mechanism. For illustrative purposes, three beamlets and three holes are used, for example, in Figure 3 The beamlets generated after the primary electron beam passes through the pre-beamlet forming mechanism may include an on-axis primary beamlet and at least an off-axis primary beamlet. In some embodiments, a plurality of off-axis beamlets may be generated. The pre-beamlet forming mechanism may include an on-axis hole and at least one off-axis hole set (e.g. Fig. 11B off-axis hole set 1105C).

[0178] In some embodiments, the off-axis aperture set 1105C may include active apertures (eg, Fig.11E Active aperture 1105_C6A). Exemplary active aperture 1105_C6A may include a top aperture plate (e.g. Fig.11E The top aperture plate 1120 of FIG. 1120 ), active deflectors (eg Fig.11E active deflector 1130) and a bottom aperture plate (eg Fig.11E The bottom aperture plate 1140 of the active aperture 1105_C6A is shown as including three elements, but it is understood that there may be more elements, such as spacer layers, micro lenses, etc., as appropriate. In some embodiments, the active aperture 1105_C6A may include an active aperture assembly manufactured using techniques including but not limited to machining, MEMS manufacturing techniques, chemical etching, laser cutting, micromachining, etc. Based on the application, the pre-beamlet forming mechanism 172B including the active aperture array may be made of conductive, semiconductor, or insulating materials.

[0179] The top aperture plate may be configured to allow a portion of the electrons in the primary electron beam to pass through based on a desired current setting. The bottom aperture plate may include a plurality of off-axis apertures (e.g., Fig.11E The top and bottom aperture plates may be electrically grounded or maintained at a reference voltage. The active deflector may include a unipolar deflector or a multipolar deflector configured to be electrically activated to affect the path of a portion of the electrons in the primary electron beam.

[0180] The active deflector can be electrically activated by applying an electrical signal to one or more poles. In some embodiments, the electrical signal can include a voltage signal suitable for deflecting a portion of the electrons in the primary electron beam that leave the off-axis hole 1122. In some embodiments, the active deflector can be electrically activated to deflect the peripheral electrons of the primary electron beam so that they may be blocked by the bottom aperture plate. The deflection of the peripheral electrons can be determined based on the characteristics of the electrical signal applied to the active deflector. The electrical signal can include a voltage signal, and the characteristics of the voltage signal can include polarity, amplitude, etc.

[0181] The shape or cross-section of the on-axis hole can be circular or substantially circular. The cross-section of the hole in the off-axis hole set can be circular, rectangular, substantially circular, elliptical, polygonal, etc. The cross-section of the hole can determine the cross-section and shape of the primary beamlet generated thereby. The primary beamlet generated by the hole of the pre-beamlet forming mechanism 172B can be incident on a focusing lens (e.g. Figure 2 on the focusing lens 110).

[0182] In step 1430, a plurality of detection beamlets may be generated from the plurality of primary beamlets by means of a beam-limiting aperture array. On-axis detection beamlets may be associated with corresponding on-axis primary beamlets, and off-axis detection beamlets may be associated with corresponding off-axis aperture sets in pre-beamlet forming mechanism 172B. Characteristics of the formed detection beamlets may be determined based on characteristics of the beam-limiting aperture array. Characteristics of the beam-limiting aperture array may include, but are not limited to, size, cross-section, shape, spacing, positioning of the apertures. Characteristics of the detection beamlets may be determined by one or more characteristics of the beam-limiting aperture array.

[0183] In step 1440, the probe beamlets generated by the beam-limiting aperture array may be focused and directed toward the sample (eg, Figure 2 of the sample 190) to form a detection spot (e.g. Figure 2 In some embodiments, each of the plurality of detection beamlets may form a detection spot on the sample. The detection beamlets may be formed using an objective lens (e.g. Figure 3 The probe sub-beam may be incident perpendicular to the sample surface. The primary electrons of the probe sub-beam incident on the sample may generate secondary electrons. The secondary electrons may be detected using a secondary electron detector or a backscattered electron detector, thereby revealing information about the sample being detected.

[0184] The embodiments may also be described using the following terms:

[0185] 1. A charged particle beam device, comprising:

[0186] a charged particle source configured to generate a primary charged particle beam along a primary optical axis;

[0187] a first aperture array comprising a first plurality of apertures configured to generate a plurality of primary beamlets from a primary charged particle beam;

[0188] a condenser lens including a flat surface adjustable along a primary optical axis; and

[0189] a second aperture array comprising a second plurality of apertures configured to generate a plurality of detection beamlets,

[0190] wherein each of the plurality of detection beamlets comprises a portion of the charged particles of the corresponding primary beamlet, and

[0191] The portion of charged particles is determined based at least on the position of the plane of the focusing lens and on properties of the second aperture array.

[0192] 2. Apparatus according to clause 1, wherein the first aperture array comprises a pre-beamlet forming aperture array arranged between the charged particle source and the focusing lens.

[0193] 3. Apparatus according to any of clauses 1 and 2, wherein the first array of apertures comprises on-axis apertures configured to generate on-axis beamlets incident on on-axis apertures of the second array of apertures.

[0194] 4. Apparatus according to any of clauses 1 to 3, wherein the first array of apertures comprises off-axis apertures configured to generate off-axis beamlets which are incident on corresponding off-axis apertures of the second array of apertures.

[0195] 5. Apparatus according to clause 4, wherein the off-axis holes of the first array of holes comprise elongated holes having rounded ends and a gradually narrowing width.

[0196] 6. Apparatus according to clause 5, wherein the off-axis holes of the first array of holes have a curved form.

[0197] 7. Apparatus according to any of clauses 4 to 6, wherein the off-axis aperture is oriented such that the width tapers towards the primary optical axis.

[0198] 8. Apparatus according to any of clauses 4 to 7, wherein the condenser lens is configured to cause a portion of the off-axis beamlets to form a corresponding detection beamlet of the plurality of detection beamlets.

[0199] 9. Apparatus according to any one of clauses 1 to 8, wherein the second aperture array comprises a beam limiting aperture array arranged between the focusing lens and the objective lens.

[0200] 10. Apparatus according to any of clauses 1 to 9, wherein the second plurality of apertures is configured to determine a size and a shape of the plurality of detection beamlets.

[0201] 11. Apparatus according to any of clauses 1 to 10, wherein the characteristic of the second array of holes comprises at least one of the size, shape and arrangement of the second plurality of holes.

[0202] 12. The apparatus according to any one of clauses 1 to 11, wherein the focusing lens comprises an electrostatic lens, an electromagnetic lens or an electromagnetic compound lens.

[0203] 13. Apparatus according to any one of clauses 1 to 12, wherein the first plurality of holes comprises a plurality of off-axis holes.

[0204] 14. The apparatus of clause 13, wherein the plurality of off-axis apertures comprises an aperture in which a first off-axis aperture overlaps with a second off-axis aperture, wherein the first off-axis aperture enables the second aperture array to generate a first off-axis detection beamlet, and the second off-axis aperture enables the second aperture array to generate a second off-axis detection beamlet.

[0205] 15. The apparatus of clause 13, wherein each off-axis hole of the plurality of off-axis holes of the first hole array is separated by a substrate material of the first hole array.

[0206] 16. Apparatus according to any one of clauses 3 to 15, wherein the on-axis holes of the first array of holes are substantially circular.

[0207] 17. Apparatus according to any of clauses 4 to 16, wherein the area of ​​the on-axis holes of the first array of holes is substantially similar to the area of ​​the off-axis holes.

[0208] 18. A first hole array, comprising:

[0209] a first plurality of apertures configured to generate a plurality of primary beamlets from a primary charged particle beam, wherein:

[0210] a portion of the charged particles of a primary beamlet of the plurality of primary beamlets forms a corresponding detection beamlet of the plurality of detection beamlets, and

[0211] The portion of charged particles is determined based on at least a position of a plane of the condenser lens and a characteristic of a second aperture array, wherein the second aperture array is configured to generate a plurality of detection beamlets.

[0212] 19. The first aperture array according to clause 18, further comprising a pre-beamlet forming aperture array arranged between the charged particle source and the focusing lens.

[0213] 20. The first aperture array according to any of clauses 18 and 19, further comprising an on-axis aperture configured to generate an on-axis beamlet incident on the on-axis aperture of the second aperture array.

[0214] 21. The first aperture array according to any of clauses 18 to 20, further comprising an off-axis aperture configured to generate an off-axis beamlet incident on a corresponding off-axis aperture of the second aperture array.

[0215] 22. The first array of holes according to clause 21, wherein the off-axis holes comprise elongated holes having rounded ends and a gradually narrowing width.

[0216] 23. The first array of holes according to clause 22, wherein the off-axis holes have a curved form.

[0217] 24. A first array of apertures according to any of clauses 21 to 23, wherein the off-axis apertures are oriented such that the width tapers towards the primary optical axis.

[0218] 25. The first array of holes according to any one of clauses 18 to 24, wherein the first plurality of holes comprises a plurality of off-axis holes.

[0219] 26. A first aperture array according to clause 25, wherein the plurality of off-axis apertures comprises an aperture in which a first off-axis aperture overlaps with a second off-axis aperture, wherein the first off-axis aperture enables the second aperture array to generate a first off-axis detection beamlet, and the second off-axis aperture enables the second aperture array to generate a second off-axis detection beamlet.

[0220] 27. The first hole array according to any of clauses 25 and 26, wherein each off-axis hole in the plurality of off-axis holes is separated by a substrate material of the first hole array.

[0221] 28. A first hole array according to any one of clauses 20 to 27, wherein the on-shaft holes are substantially circular.

[0222] 29. A first hole array according to any one of clauses 21 to 28, wherein the area of ​​the on-axis holes and the area of ​​the off-axis holes of the first hole array are substantially similar.

[0223] 30. A method for observing a sample using a multi-beam device, the method comprising:

[0224] activating a charged particle source to generate a primary charged particle beam;

[0225] generating a plurality of primary beamlets from a primary charged particle beam using a first aperture array;

[0226] generating, using a second aperture array, a plurality of probe beamlets corresponding to the plurality of primary beamlets;

[0227] adjusting the position of the plane of the condenser lens with respect to the first array of apertures and the second array of apertures along the primary optical axis; and

[0228] generating a plurality of detection spots incident on the sample surface from the plurality of detection beamlets,

[0229] wherein each of the plurality of detection beamlets comprises a portion of the charged particles of a corresponding primary beamlet of the plurality of primary beamlets, and

[0230] The portion of charged particles is determined based at least on the position of the plane of the focusing lens and on properties of the second aperture array.

[0231] 31. A method according to clause 30, wherein adjusting the position of the plane of the condenser lens modifies the characteristics of the detection beamlets.

[0232] 32. A method according to any of clauses 30 and 31, wherein adjusting the position of the plane of the condenser lens modifies the current of the detection beamlets.

[0233] 33. The method according to any of clauses 30 to 32, wherein generating the plurality of primary beamlets comprises generating on-axis beamlets and off-axis beamlets.

[0234] 34. The method of clause 33, further comprising: using a condenser lens, causing the portion of the off-axis beamlets to form a corresponding probe beamlet of the plurality of probe beamlets.

[0235] 35. A non-transitory computer readable medium storing a set of instructions executable by one or more processors of a multi-beam device having a first array of apertures and a second array of apertures to cause the multi-beam device to perform a method comprising:

[0236] activating a charged particle source to generate a primary charged particle beam; and

[0237] The position of the plane of the condenser lens is adjusted along the primary optical axis with respect to the first array of holes and the second array of holes, wherein:

[0238] the first aperture array being configured to generate a plurality of primary beamlets from the primary charged particle beam using a first plurality of apertures,

[0239] a portion of the charged particles of a primary beamlet of the plurality of primary beamlets forms a corresponding detection beamlet, and

[0240] The fraction of charged particles is determined based at least on the position of the plane of the condenser lens and on the properties of the second aperture array.

[0241] 36. A charged particle beam apparatus comprising:

[0242] a charged particle source configured to generate a primary charged particle beam along a primary optical axis;

[0243] a first aperture array comprising a plurality of aperture sets configured to form a plurality of primary beamlets from a primary charged particle beam;

[0244] a condenser lens disposed on a plane perpendicular to the primary optical axis; and

[0245] a second aperture array comprising a plurality of apertures configured to generate a plurality of detection beamlets,

[0246] wherein a probe beamlet of the plurality of probe beamlets is associated with a set of apertures in a first array of apertures, and

[0247] The apertures in the set of apertures in which the detection beamlets are formed are determined at least based on the properties of the condenser lens.

[0248] 37. Apparatus according to clause 36, wherein the first array of apertures comprises an array of pre-beamlet forming apertures arranged between the charged particle source and the focusing lens.

[0249] 38. Apparatus according to any of clauses 36 and 37, wherein the first array of apertures comprises on-axis apertures configured to generate on-axis primary beamlets incident on on-axis apertures of the second array of apertures.

[0250] 39. Apparatus according to any of clauses 36 to 38, wherein the first array of apertures comprises a plurality of off-axis sets of apertures configured to generate a plurality of off-axis primary beamlets which are incident on corresponding off-axis apertures of the second array of apertures.

[0251] 40. Apparatus according to any of clauses 36 to 39, wherein a set of the plurality of sets of off-axis apertures comprises apertures arranged along a tortuous path.

[0252] 41. Apparatus according to any of clauses 36 to 40, wherein a set of the plurality of sets of off-axis holes comprises at least two holes having different sizes.

[0253] 42. Apparatus according to any of clauses 36 to 41, wherein a set of the plurality of sets of off-axis apertures comprises apertures sized to determine a current of a corresponding primary beamlet.

[0254] 43. Apparatus according to any of clauses 36 to 42, wherein a set of the plurality of sets of off-axis holes comprises holes having uniform spacing.

[0255] 44. Apparatus according to any of clauses 36 to 42, wherein a set of the plurality of sets of off-axis holes comprises holes having non-uniform spacing.

[0256] 45. Apparatus according to any of clauses 36 to 44, wherein the plurality of off-axis hole sets comprises holes having circular, rectangular, elliptical or polygonal cross-sections.

[0257] 46. ​​Apparatus according to any of clauses 36 to 45, wherein the condenser lens is configured to cause a primary beamlet of the plurality of primary beamlets to form a corresponding detection beamlet of the plurality of detection beamlets.

[0258] 47. Apparatus according to any of clauses 36 to 46, wherein the second aperture array comprises a beam limiting aperture array arranged between the focusing lens and the objective lens.

[0259] 48. Apparatus according to any of clauses 36 to 47, wherein the second plurality of apertures is configured to determine a size and a shape of the plurality of detection beamlets.

[0260] 49. The apparatus of any one of clauses 36 to 48, wherein the focusing lens comprises an electrostatic lens, an electromagnetic lens or an electromagnetic compound lens.

[0261] 50. Apparatus according to any of clauses 38 to 49, wherein the on-axis holes of the first array of holes are substantially circular.

[0262] 51. A first hole array, comprising:

[0263] a plurality of aperture sets configured to form a plurality of primary beamlets from a primary charged particle beam, wherein:

[0264] A probe beamlet of the plurality of probe beamlets is associated with a set of a plurality of sets of apertures of the first aperture array, and

[0265] The apertures in the set of apertures in which the detection beamlets are formed are determined at least based on the properties of the condenser lens.

[0266] 52. The first aperture array according to clause 51, further comprising a pre-beamlet forming aperture array disposed between the charged particle source and the focusing lens.

[0267] 53. The first aperture array according to any of clauses 51 and 52, further comprising an on-axis aperture configured to generate an on-axis primary beamlet incident on the on-axis aperture of the second aperture array.

[0268] 54. The first hole array according to clause 53, wherein the on-shaft holes are substantially circular.

[0269] 55. The first aperture array of any of clauses 51 to 54, wherein the plurality of off-axis aperture sets are configured to generate a plurality of off-axis beamlets that are incident on corresponding off-axis apertures in the second aperture array.

[0270] 56. The first array of holes according to any of clauses 51 to 55, wherein a set of the plurality of sets of off-axis holes comprises holes arranged along a tortuous path.

[0271] 57. The first array of holes according to any of clauses 51 to 56, wherein a set in the plurality of sets of off-axis holes comprises at least two holes having different sizes.

[0272] 58. A first array of apertures according to any of clauses 51 to 57, wherein a set of the plurality of sets of off-axis apertures comprises apertures sized to determine a current of a corresponding primary beamlet.

[0273] 59. The first array of holes according to any one of clauses 51 to 58, wherein a set of the plurality of sets of off-axis holes comprises holes having uniform spacing.

[0274] 60. The first array of holes according to any of clauses 51 to 58, wherein a set of the plurality of sets of off-axis holes comprises holes having non-uniform spacing.

[0275] 61. The first array of holes according to any one of clauses 51 to 60, wherein the plurality of off-axis hole sets comprises holes having a circular, rectangular, elliptical or polygonal cross-section.

[0276] 62. A method for observing a sample using a multi-beam device, the method comprising:

[0277] activating a charged particle source to generate a primary charged particle beam;

[0278] generating a plurality of primary beamlets from a primary charged particle beam using a first aperture array;

[0279] generating, using a second aperture array, a plurality of probe beamlets corresponding to the plurality of primary beamlets;

[0280] adjusting the position of the plane of the condenser lens with respect to the first array of apertures and the second array of apertures along the primary optical axis; and

[0281] generating a plurality of detection spots incident on the sample surface from the plurality of detection beamlets,

[0282] wherein a probe beamlet of the plurality of probe beamlets is associated with a set of apertures of a first aperture array, and

[0283] The apertures in the set of apertures in which the detection beamlets are formed are determined at least based on the properties of the condenser lens.

[0284] 63. A method according to clause 62, wherein adjusting the position of the plane of the condenser lens modifies the characteristics of the detection beamlets.

[0285] 64. A method according to any of clauses 62 and 63, wherein adjusting the position of the plane of the condenser lens modifies the current of the detection beamlets.

[0286] 65. The method of any of clauses 62 to 64, wherein generating a plurality of primary beamlets comprises generating on-axis primary beamlets and off-axis primary beamlets.

[0287] 66. The method of clause 65, further comprising: using a condenser lens to form the off-axis primary beamlet into a corresponding detection beamlet of the plurality of detection beamlets.

[0288] 67. A non-transitory computer readable medium storing a set of instructions executable by one or more processors of a multi-beam device having a first array of apertures and a second array of apertures to cause the multi-beam device to perform a method comprising:

[0289] activating a charged particle source to generate a primary charged particle beam; and

[0290] The position of the plane of the condenser lens is adjusted along the primary optical axis with respect to the first array of holes and the second array of holes, wherein:

[0291] The first aperture array is configured to generate a plurality of primary beamlets from the primary charged particle beam using a plurality of aperture sets,

[0292] A primary beamlet of the plurality of primary beamlets forms a corresponding detection beamlet, and

[0293] The apertures in the set of apertures forming the detection beamlets are determined based at least on the properties of the condenser lens.

[0294] 68. A charged particle beam apparatus comprising:

[0295] a first aperture array, the first aperture array comprising a first plurality of apertures, the first plurality of apertures being configured to form a plurality of primary beamlets from a primary charged particle beam, the apertures in the first plurality of apertures comprising:

[0296] a first aperture plate configured to be at a first voltage; and

[0297] A second aperture plate is configured to be at a second voltage different from the first voltage to generate an electric field that enables adjustment of the paths of the charged particles of the primary charged particle beam.

[0298] 60. The apparatus of clause 68, further comprising: a third aperture plate configured to be at a third voltage substantially similar to the first voltage.

[0299] 70. The apparatus according to any one of clauses 68 and 69, further comprising:

[0300] a condenser lens including a flat surface adjustable along a primary optical axis; and

[0301] a second aperture array comprising a second plurality of apertures configured to generate a plurality of detection beamlets,

[0302] Each of the plurality of detection beamlets comprises a portion of charged particles of a corresponding primary beamlet, and the portion of charged particles is based at least on a position of a plane of the condenser lens and a characteristic of the second aperture array.

[0303] 71. The device of any of clauses 69 and 70, wherein the first voltage and the third voltage comprise reference voltages.

[0304] 72. Apparatus according to any of clauses 68 to 71, wherein the second aperture plate comprises a charged particle beam deflector configured to adjust a path of the charged particles in response to electrical activation.

[0305] 73. Apparatus according to clause 72, wherein the charged particle beam deflector comprises a monopole deflector or a multipole deflector.

[0306] 74. Apparatus according to any of clauses 72 and 73, wherein electrical activation of the second aperture plate comprises a voltage signal being applied to generate an electric field.

[0307] 75. The apparatus of clause 74, wherein the path of the charged particles is adjusted based on a characteristic of a voltage signal applied to the second aperture plate.

[0308] 76. The device of clause 75, wherein the characteristic of the voltage signal comprises polarity or amplitude.

[0309] 77. The apparatus of any one of clauses 69 to 76, wherein the holes in the first plurality of holes comprise:

[0310] a first well in a first well plate;

[0311] a second hole in a second hole plate; and

[0312] The third hole in the third hole plate,

[0313] wherein the second orifice plate is disposed between the first orifice plate and the third orifice plate, and

[0314] The geometric centers of the first hole, the second hole and the third hole are aligned.

[0315] 78. The device of clause 77, wherein the first aperture and the second aperture are different in size, and wherein the first aperture and the third aperture are substantially similar in size.

[0316] 79. Apparatus according to any of clauses 77 to 78, wherein the third aperture plate is configured to block a portion of the charged particles from leaving the second aperture.

[0317] 80. Apparatus according to any of clauses 70 to 79, wherein the first array of apertures comprises an array of pre-beamlet forming apertures arranged between the charged particle source and the focusing lens.

[0318] 81. Apparatus according to any of clauses 70 to 80, wherein the first array of apertures comprises on-axis apertures configured to generate on-axis beamlets incident on on-axis apertures of the second array of apertures.

[0319] 82. Apparatus according to any of clauses 70 to 81, wherein the first array of apertures comprises off-axis apertures configured to generate off-axis beamlets which are incident on corresponding off-axis apertures of the second array of apertures.

[0320] 83. The apparatus of clause 82, wherein the off-axis holes of the first array of holes comprise elongated holes having rounded ends and a gradually narrowing width.

[0321] 84. Apparatus according to clause 83, wherein the off-axis holes of the first array of holes have a curved form.

[0322] 85. Apparatus according to any of clauses 82 to 84, wherein the off-axis aperture is oriented such that the width tapers towards the primary optical axis.

[0323] 86. Apparatus according to any of clauses 82 to 85, wherein the condenser lens is configured to cause a portion of the off-axis beamlets to form a corresponding detection beamlet of the plurality of detection beamlets.

[0324] 87. Apparatus according to any of clauses 70 to 86, wherein the second aperture array comprises a beam limiting aperture array arranged between the focusing lens and the objective lens.

[0325] 88. Apparatus according to any of clauses 70 to 87, wherein the second plurality of apertures is configured to determine a size and a shape of the plurality of detection beamlets.

[0326] 89. Apparatus according to any of clauses 70 to 88, wherein the characteristic of the second array of holes comprises at least one of the size, shape and arrangement of the second plurality of holes.

[0327] 90. An apparatus according to any one of clauses 70 to 89, wherein the focusing lens comprises an electrostatic lens, an electromagnetic lens or an electromagnetic compound lens.

[0328] 91. Apparatus according to any one of clauses 68 to 90, wherein the first plurality of holes comprises a plurality of off-axis holes.

[0329] 92. A device according to clause 91, wherein the plurality of off-axis holes include holes in which a first off-axis hole overlaps with a second off-axis hole, wherein the first off-axis hole enables the second hole array to generate a first off-axis detection beamlet, and the second off-axis hole enables the second hole array to generate a second off-axis detection beamlet.

[0330] 93. Apparatus according to any of clauses 91 to 92, wherein each off-axis hole in the plurality of off-axis holes of the first array of holes is separated by a substrate material of the first array of holes.

[0331] 94. Apparatus according to any one of clauses 81 to 93, wherein the on-axis holes of the first array of holes are substantially circular.

[0332] 95. Apparatus according to any one of clauses 82 to 94, wherein the area of ​​the on-axis holes of the first array of holes is substantially similar to the area of ​​the off-axis holes.

[0333] 96. A method for observing a sample using a charged particle beam apparatus, the method comprising:

[0334] activating a charged particle source to generate a primary charged particle beam;

[0335] generating a plurality of primary beamlets from a primary charged particle beam using a first aperture plate and a second aperture plate of a first aperture array, wherein the first aperture plate is operated at a first voltage and the second aperture plate is operated at a second voltage different from the first voltage for adjusting a path of the charged particles exiting the first aperture plate;

[0336] generating, using the second aperture array, a plurality of probe beamlets corresponding to the plurality of primary beamlets; and

[0337] A plurality of detection spots incident on the sample surface are generated from the plurality of detection beamlets.

[0338] 97. The method of clause 96, further comprising: operating the third aperture plate at a third voltage substantially similar to the first voltage, wherein the first voltage and the third voltage comprise a reference voltage.

[0339] 98. The method according to any one of clauses 96 and 97, further comprising: adjusting the path of the charged particles by electrically activating the second aperture plate.

[0340] 99. The method of clause 98, wherein electrically activating the second aperture plate comprises applying a voltage signal to generate an electric field.

[0341] 100. The method of any one of clauses 96 to 99, further comprising adjusting a position of a plane of the focusing lens relative to the first array of apertures and the second array of apertures along the primary optical axis.

[0342] 101. A method according to clause 100, wherein adjusting the position of the plane of the focusing lens modifies the characteristics of the plurality of detection beamlets.

[0343] 102. A method according to any of clauses 100 and 101, wherein adjusting the position of the plane of the condenser lens modifies the current of the plurality of detection beamlets.

[0344] 103. The method of any of clauses 96 to 102, wherein generating the plurality of primary beamlets comprises generating on-axis beamlets and off-axis beamlets.

[0345] 104. The method of any of clauses 100 to 103, further comprising: using a condenser lens to cause a portion of the off-axis beamlets to form a corresponding detection beamlet of the plurality of detection beamlets.

[0346] 105. A non-transitory computer readable medium storing a set of instructions executable by one or more processors of a multi-beam device having a first array of apertures and a second array of apertures to cause the multi-beam device to perform a method comprising:

[0347] activating a charged particle source to generate a primary charged particle beam;

[0348] generating a plurality of primary beamlets from a primary charged particle beam using a first aperture plate and a second aperture plate of a first aperture array, wherein the first aperture plate and the third aperture plate are operated substantially at a first voltage, and the second aperture plate is operated at a second voltage different from the first voltage for adjusting a path of the charged particles exiting the first aperture plate;

[0349] generating, using the second aperture array, a plurality of probe beamlets corresponding to the plurality of primary beamlets; and

[0350] A plurality of detection spots incident on the sample surface are generated from the plurality of detection beamlets.

[0351] 106. A charged particle beam apparatus comprising:

[0352] a first aperture array, the first aperture array comprising a first plurality of apertures, the first plurality of apertures being configured to form a plurality of primary beamlets from a primary charged particle beam, the apertures in the first plurality of apertures comprising:

[0353] a first aperture plate configured to be at a first voltage; and

[0354] a second aperture plate configured to be at a second voltage different from the first voltage for generating an electric field between the first aperture plate and the second aperture plate; and

[0355] A second aperture array is configured to generate detection beamlets from corresponding primary beamlets, wherein beam currents of the detection beamlets are adjustable.

[0356] 107. The apparatus of clause 106, wherein the electric field between the first aperture plate and the second aperture plate is substantially fixed.

[0357] 108. The apparatus of any of clauses 106 and 107, wherein the beam current is discretely adjusted based on the size of the apertures in the first plurality of apertures in the first array of apertures.

[0358] 109. The apparatus of clause 106, wherein the electric field between the first aperture plate and the second aperture plate is adjustable.

[0359] 110. The apparatus of any of clauses 106 and 109, wherein the beam current is adjusted based on an electric field between the first aperture plate and the second aperture plate.

[0360] 111. Apparatus according to any of clauses 106 to 110, wherein the electric field is configured to enable adjustment of the path of the charged particles of the primary charged particle beam.

[0361] 112. The apparatus of any of clauses 106 to 111, further comprising: a third aperture plate configured to be at a third voltage substantially similar to the first voltage.

[0362] 113. The device of clause 112, wherein the first voltage and the third voltage comprise reference voltages.

[0363] 114. Apparatus according to any of clauses 111 to 113, wherein the second aperture plate comprises a charged particle beam deflector configured to adjust a path of the charged particles in response to electrical activation.

[0364] 115. Apparatus according to clause 114, wherein the charged particle beam deflector comprises a monopole deflector or a multipole deflector.

[0365] 116. The device of any of clauses 114 and 115, wherein electrical activation of the second aperture plate comprises a voltage signal being applied to generate an electric field.

[0366] 117. The apparatus of clause 116, wherein the path of the charged particles is adjusted based on a characteristic of a voltage signal applied to the second aperture plate.

[0367] 118. The apparatus of any of clauses 106 to 117, wherein the holes in the first plurality of holes comprise:

[0368] a first well in a first well plate;

[0369] a second hole in a second hole plate; and

[0370] The third hole in the third hole plate,

[0371] wherein the second orifice plate is disposed between the first orifice plate and the third orifice plate, and

[0372] The geometric centers of the first hole, the second hole and the third hole are aligned.

[0373] 119. The device of clause 118, wherein the first aperture and the second aperture are different in size, and wherein the first aperture and the third aperture are substantially similar in size.

[0374] 120. Apparatus according to any of clauses 118 to 119, wherein the third aperture plate is configured to block a portion of the charged particles from leaving the second aperture.

[0375] 121. Apparatus according to any of clauses 106 to 120, wherein the first array of apertures comprises on-axis apertures configured to generate on-axis beamlets incident on on-axis apertures of the second array of apertures.

[0376] 122. Apparatus according to any of clauses 106 to 121, wherein the first array of apertures comprises off-axis apertures configured to generate off-axis beamlets which are incident on corresponding off-axis apertures of the second array of apertures.

[0377] 123. An apparatus according to clause 122, wherein the off-axis holes of the first array of holes comprise elongated holes having rounded ends and a gradually narrowing width.

[0378] 124. Apparatus according to clause 123, wherein the off-axis holes of the first array of holes have a curved form.

[0379] 125. Apparatus according to any of clauses 122 to 124, wherein the off-axis aperture is oriented such that the width tapers towards the primary optical axis.

[0380] 126. The apparatus of any of clauses 122 to 125, further comprising a condenser lens configured to cause a portion of the off-axis beamlets to form a corresponding detection beamlet.

[0381] 127. Apparatus according to clause 126, wherein the second aperture array comprises a beam limiting aperture array arranged between the focusing lens and the objective lens.

[0382] 128. Apparatus according to any of clauses 106 to 127, wherein the second array of apertures comprises a second plurality of apertures configured to generate a plurality of detection beamlets.

[0383] 129. The apparatus of clause 128, wherein the second plurality of apertures is configured to determine a size and a shape of the plurality of detection beamlets.

[0384] 130. Apparatus according to any of clauses 126 to 129, wherein the detection beamlet comprises a portion of the charged particles of the corresponding primary beamlet based at least on the position of the plane of the condenser lens and the characteristics of the second array of apertures.

[0385] 131. The apparatus of clause 130, wherein the characteristic of the second array of holes comprises at least one of a size, a shape, and an arrangement of the second plurality of holes.

[0386] 132. An apparatus according to any one of clauses 126 to 131, wherein the focusing lens comprises an electrostatic lens, an electromagnetic lens or an electromagnetic compound lens.

[0387] 133. The apparatus of any of clauses 106 to 132, wherein the first plurality of holes comprises a plurality of off-axis holes.

[0388] 134. A device according to clause 133, wherein the plurality of off-axis holes include a first off-axis hole overlapping a second off-axis hole, wherein the first off-axis hole enables the second hole array to generate a first off-axis detection beamlet, and the second off-axis hole enables the second hole array to generate a second off-axis detection beamlet.

[0389] 135. The apparatus of any of clauses 133 and 134, wherein each off-axis hole in the plurality of off-axis holes of the first array of holes is separated by a substrate material of the first array of holes.

[0390] 136. Apparatus according to any one of clauses 121 to 135, wherein the on-axis holes of the first array of holes are substantially circular.

[0391] 137. Apparatus according to any of clauses 121 to 136, wherein the area of ​​the on-axis holes of the first array of holes is substantially similar to the area of ​​the off-axis holes.

[0392] 138. A method for observing a sample using a charged particle beam apparatus, the method comprising:

[0393] activating a charged particle source to generate a primary charged particle beam;

[0394] generating a plurality of primary beamlets from a primary charged particle beam using a first aperture plate and a second aperture plate of a first aperture array, wherein the first aperture plate is operated at a first voltage and the second aperture plate is operated at a second voltage different from the first voltage to adjust a path of the charged particles exiting the first aperture plate;

[0395] generating probe beamlets from corresponding primary beamlets using a second aperture array, wherein beam currents of the probe beamlets are adjustable; and

[0396] A detection spot is generated from the detection beamlets, which is incident on the sample surface.

[0397] 139. The method of clause 138, wherein adjusting the path of the charged particle comprises: deflecting the charged particle based on an electric field formed between the first aperture plate and the second aperture plate.

[0398] 140. The method according to clauses 138 and 139, wherein the electric field between the first aperture plate and the second aperture plate is substantially fixed, and wherein adjusting the beam current of the detection sub-beam is based on the size of the apertures of the first aperture array.

[0399] 141. The method according to clauses 138 and 139, wherein the electric field between the first aperture plate and the second aperture plate is adjustable, and wherein adjusting the beam current of the detection sub-beam comprises: adjusting the electric field between the first aperture plate and the second aperture plate.

[0400] 142. A method according to any of clauses 139 to 141, wherein deflecting the charged particles is caused by electrically activating the second aperture plate by applying a voltage signal to generate an electric field.

[0401] 143. The method of any of clauses 138 to 142, further comprising: operating the third aperture plate at a third voltage substantially similar to the first voltage, wherein the first voltage and the third voltage comprise a reference voltage.

[0402] 144. The method according to any of clauses 138 to 143, further comprising: adjusting the position of the plane of the condenser lens relative to the first array of apertures and the second array of apertures along the primary optical axis.

[0403] 145. A method according to clause 144, wherein adjusting the position of the plane of the focusing lens modifies the characteristics of the detection sub-beams.

[0404] 146. A method according to any of clauses 144 and 145, wherein adjusting the position of the plane of the focusing lens modifies the beam current of the detection sub-beam.

[0405] 147. The method of any of clauses 144 to 146, further comprising: using a focusing lens to cause a portion of the off-axis primary beamlets to form a corresponding detection beamlet.

[0406] 148. The method of any of clauses 138 to 147, wherein generating a plurality of primary beamlets comprises generating on-axis primary beamlets and off-axis primary beamlets.

[0407] 149. A non-transitory computer readable medium storing a set of instructions executable by one or more processors of a multi-beam device having a first array of apertures and a second array of apertures to cause the multi-beam device to perform a method comprising:

[0408] activating a charged particle source to generate a primary charged particle beam;

[0409] generating a plurality of primary beamlets from a primary charged particle beam using a first aperture plate and a second aperture plate of a first aperture array, wherein the first aperture plate is operated at a first voltage and the second aperture plate is operated at a second voltage different from the first voltage to adjust a path of the charged particles exiting the first aperture plate;

[0410] generating probe beamlets from corresponding primary beamlets using a second aperture array, wherein beam currents of the probe beamlets are adjustable; and

[0411] A detection spot is generated from the detection beamlets, which is incident on the sample surface.

[0412] 150. A charged particle beam apparatus comprising:

[0413] a set of pre-beamlet forming apertures configured to form a plurality of primary beamlets from a primary charged-particle beam; and

[0414] a beam-limiting aperture configured to generate a detection beamlet from a corresponding primary beamlet, wherein a beam current of the detection beamlet is determined based on characteristics of an aperture in a set of pre-beamlet-forming apertures forming the primary beamlet,

[0415] Each aperture in the set of pre-beamlet forming apertures is configured to influence a beam current of a formed detection beamlet.

[0416] 151. Apparatus according to clause 150, wherein the characteristics of the apertures in the set of pre-beamlet forming apertures comprise the size, shape or position of the apertures.

[0417] 152. Apparatus according to any of clauses 150 and 151, wherein the beam current of the detection beamlet is discretely adjusted based on the size of the apertures in the set of pre-beamlet forming apertures.

[0418] 153. Apparatus according to any one of clauses 150 to 152, comprising:

[0419] a first array of a plurality of sets of pre-beamlet forming apertures; and

[0420] A second array of a plurality of beam-limiting apertures is arranged downstream of the first array along the primary optical axis of the primary charged-particle beam.

[0421] 154. Apparatus according to any of clauses 150 to 153, wherein the apertures in the set of pre-beamlet forming apertures forming the detection beamlets are determined based on characteristics of a condenser lens.

[0422] 155. A device according to clause 154, wherein the characteristic of the focusing lens includes the position of the plane of the focusing lens along the primary optical axis.

[0423] 156. Apparatus according to any of clauses 154 and 155, wherein a change in the position of the plane of the condenser lens is configured to influence the beam current of the detection beamlets.

[0424] 157. Apparatus according to any of clauses 154 to 156, wherein the focusing lens is configured to influence the beam current of the detection beamlets by directing parts of the primary charged particle beam through different apertures in the set of pre-beamlet forming apertures.

[0425] 158. Apparatus according to any one of clauses 155 to 157, wherein:

[0426] a condenser lens at a first position in the plane configured to cause a first portion of the primary charged particle beam to pass through a first aperture in the set of pre-beamlet forming apertures to form a first primary beamlet; and

[0427] The condenser lens located at a second position in the plane is configured to cause a second portion of the primary charged-particle beam to pass through a second aperture in the set of pre-beamlet forming apertures to form a second primary beamlet.

[0428] 159. Apparatus according to any of clauses 153 to 158, wherein the first array comprises on-axis apertures configured to generate on-axis primary beamlets which are incident on the on-axis apertures of the second array.

[0429] 160. Apparatus according to any of clauses 153 to 159, wherein the set of pre-beamlet forming apertures comprises a plurality of off-axis pre-beamlet forming apertures configured to generate off-axis primary beamlets which are incident on corresponding off-axis beam limiting apertures in the second array.

[0430] 161. Apparatus according to clause 160, wherein each of the off-axis pre-beamlet forming apertures is separated by substrate material of the first array.

[0431] 162. Apparatus according to any of clauses 160 and 161, wherein the plurality of off-axis pre-beamlet forming apertures are arranged along a curved path.

[0432] 163. Apparatus according to any of clauses 160 to 162, wherein the plurality of off-axis pre-beamlet forming apertures comprises at least two apertures having different sizes.

[0433] 164. Apparatus according to any of clauses 160 to 163, wherein the plurality of off-axis pre-beamlet forming apertures are sized to influence beam currents of primary beamlets generated when passing through apertures in the plurality of off-axis pre-beamlet forming apertures.

[0434] 165. Apparatus according to any of clauses 160 to 164, wherein the apertures in the plurality of off-axis pre-beamlet forming apertures have uniform spacing.

[0435] 166. The first array of apertures of any of clauses 160 to 164, wherein the apertures in the plurality of off-axis pre-beamlet forming apertures have a non-uniform spacing.

[0436] A non-transitory computer readable medium may be provided that stores information for use with a controller (eg, Figure 1The controller 40 of the embodiment of the present invention is a controller that executes instructions of a processor of the controller 40) to perform image inspection, image acquisition, worktable positioning, beam focusing, electric field adjustment, beam bending, focusing lens adjustment, activation of charged particle source, beam deflection, electrical activation of active apertures, etc. Common forms of non-transitory media include, for example, floppy disks, flexible disks, hard disks, solid-state drives, magnetic tapes or any other magnetic data storage medium, compact disk read-only memory (CD-ROM), any other optical data storage medium, any physical medium with a pattern of apertures, random access memory (RAM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), flash EPROM or any other flash memory, non-volatile random access memory (NVRAM), cache, registers, any other memory chip or cartridge, and networked versions of the same.

[0437] It should be understood that the embodiments of the present disclosure are not limited to the precise constructions that have been described above and illustrated in the accompanying drawings, and that various modifications and changes may be made without departing from the scope thereof. The present disclosure has been described in conjunction with various embodiments, and other embodiments of the present invention will be apparent to those skilled in the art in view of the specification and practice of the invention disclosed herein. The description and examples are intended to be considered as exemplary only, with the true scope and spirit of the present invention being indicated by the following claims.

[0438] The above description is intended to be illustrative, rather than limiting. It will therefore be apparent to those skilled in the art that modifications may be made as described without departing from the scope of the claims set forth below.

Claims

1. A first hole array, comprising: a first plurality of apertures configured to generate a plurality of primary beamlets from a primary charged particle beam, wherein: a portion of the charged particles of a primary beamlet of the plurality of primary beamlets forms a corresponding detection beamlet of the plurality of detection beamlets, and The portion of charged particles is determined based on at least a position of a plane of the condenser lens and a characteristic of a second aperture array, wherein the second aperture array is configured to generate a plurality of detection beamlets.

2. The first aperture array according to claim 1 further comprising a pre-beamlet forming aperture array disposed between the charged particle source and the focusing lens.

3. The first aperture array according to any one of claims 1 and 2, further comprising an on-axis aperture configured to generate an on-axis beamlet, the on-axis beamlet being incident on the on-axis aperture of the second aperture array.

4. The first aperture array according to any one of claims 1 to 3, further comprising an off-axis aperture configured to generate an off-axis beamlet, the off-axis beamlet being incident on a corresponding off-axis aperture of the second aperture array.

5. The first aperture array of claim 4, wherein the off-axis apertures comprise elongated apertures having rounded ends and a tapering width.

6. The first aperture array of claim 5, wherein the off-axis apertures have a curved form.

7. A first array of apertures according to any one of claims 4 to 6, wherein the off-axis apertures are oriented such that the width tapers towards the primary optical axis.

8. A first array of holes according to any one of claims 1 to 7, wherein the first plurality of holes comprises a plurality of off-axis holes.

9. A first hole array according to claim 8, wherein the plurality of off-axis holes include a hole in which a first off-axis hole overlaps with a second off-axis hole, wherein the first off-axis hole enables the second hole array to generate a first off-axis detection beamlet, and the second off-axis hole enables the second hole array to generate a second off-axis detection beamlet.

10. The first hole array according to any one of claims 8 and 9, wherein each off-axis hole in the plurality of off-axis holes is separated by a substrate material of the first hole array.

11. A first hole array according to any one of claims 3 to 10, wherein the on-axis holes are substantially circular.

12. A first hole array according to any one of claims 4 to 11, wherein the area of ​​the on-axis holes of the first hole array is substantially similar to the area of ​​the off-axis holes.

13. A method for observing a sample using a multi-beam device, the method comprising: activating a charged particle source to generate a primary charged particle beam; generating a plurality of primary beamlets from a primary charged particle beam using a first aperture array; generating, using a second aperture array, a plurality of probe beamlets corresponding to the plurality of primary beamlets; adjusting the position of the plane of the condenser lens with respect to the first array of apertures and the second array of apertures along the primary optical axis; and generating a plurality of detection spots incident on the sample surface from the plurality of detection beamlets, wherein each of the plurality of detection beamlets comprises a portion of the charged particles of a corresponding primary beamlet of the plurality of primary beamlets, and The portion of charged particles is determined based at least on the position of the plane of the focusing lens and on properties of the second aperture array.

14. A method according to claim 13, wherein adjusting the position of the plane of the condenser lens modifies the characteristics of the detection beamlets.

15. A method according to any one of claims 13 and 14, wherein adjusting the position of the plane of the condenser lens modifies the current of the detection beamlets.

16. The method according to any one of claims 13 to 15, wherein generating a plurality of primary beamlets comprises: On-axis beamlets and off-axis beamlets are generated.

17. The method according to claim 16, further comprising: Using a condenser lens, a portion of the off-axis beamlets is caused to form a corresponding probe beamlet of the plurality of probe beamlets.

18. A non-transitory computer readable medium storing a set of instructions executable by one or more processors of a multi-beam device having a first array of apertures and a second array of apertures to cause the multi-beam device to perform a method comprising: activating a charged particle source to generate a primary charged particle beam; as well as The position of the plane of the condenser lens is adjusted along the primary optical axis with respect to the first array of holes and the second array of holes, wherein: the first aperture array being configured to generate a plurality of primary beamlets from the primary charged particle beam using a first plurality of apertures, a portion of the charged particles of a primary beamlet of the plurality of primary beamlets forms a corresponding detection beamlet, and The fraction of charged particles is determined based at least on the position of the plane of the condenser lens and on the properties of the second aperture array.

19. A charged particle beam apparatus comprising: a charged particle source configured to generate a primary charged particle beam along a primary optical axis; a first aperture array comprising a plurality of aperture sets configured to form a plurality of primary beamlets from a primary charged particle beam; A condenser lens is arranged on a plane perpendicular to the primary optical axis; as well as a second aperture array comprising a plurality of apertures configured to generate a plurality of detection beamlets, wherein a probe beamlet of the plurality of probe beamlets is associated with a set of apertures in a first array of apertures, and The apertures in the set of apertures in which the detection beamlets are formed are determined at least based on the properties of the condenser lens.

20. The apparatus of claim 19, wherein the first array of apertures comprises a pre-beamlet forming array of apertures disposed between the charged particle source and the focusing lens.

21. Apparatus according to any one of claims 19 and 20, wherein the first array of apertures comprises on-axis apertures configured to generate on-axis primary beamlets incident on on-axis apertures of the second array of apertures.

22. Apparatus according to any one of claims 19 to 21, wherein the first array of apertures comprises a plurality of off-axis aperture sets configured to generate a plurality of off-axis primary beamlets which are incident on corresponding off-axis apertures of the second array of apertures.

23. Apparatus according to any one of claims 19 to 22, wherein a set of the plurality of sets of off-axis apertures comprises apertures arranged along a tortuous path.

24. Apparatus according to any one of claims 19 to 23, wherein a set of the plurality of sets of off-axis apertures comprises at least two apertures having different sizes.

25. Apparatus according to any one of claims 19 to 24, wherein a set of the plurality of sets of off-axis apertures comprises apertures sized to determine the current of the corresponding primary beamlet.

26. Apparatus according to any one of claims 19 to 25, wherein a set of the plurality of sets of off-axis holes comprises holes having uniform spacing.

27. Apparatus according to any one of claims 19 to 25, wherein a set of the plurality of sets of off-axis apertures comprises apertures having non-uniform spacing.

28. Apparatus according to any one of claims 19 to 27, wherein the plurality of off-axis aperture sets comprises apertures having circular, rectangular, elliptical or polygonal cross-sections.

29. An apparatus according to any one of claims 19 to 28, wherein the condenser lens is configured to cause a primary beamlet of the plurality of primary beamlets to form a corresponding detection beamlet of the plurality of detection beamlets.

30. Apparatus according to any one of claims 19 to 29, wherein the second array of apertures comprises an array of beam limiting apertures arranged between the focusing lens and the objective lens.

31. Apparatus according to any one of claims 19 to 30, wherein the second plurality of apertures is configured to determine a size and a shape of the plurality of detection beamlets.

32. An apparatus according to any one of claims 19 to 31, wherein the focusing lens comprises an electrostatic lens, an electromagnetic lens or an electromagnetic compound lens.

33. Apparatus according to any one of claims 21 to 32, wherein the on-axis holes of the first array of holes are substantially circular.

34. A first hole array, comprising: a plurality of aperture sets configured to form a plurality of primary beamlets from a primary charged particle beam, wherein: A probe beamlet of the plurality of probe beamlets is associated with a set of a plurality of sets of apertures of the first aperture array, and The apertures in the set of apertures in which the detection beamlets are formed are determined at least based on the properties of the condenser lens.

35. The first aperture array of claim 34, further comprising a pre-beamlet forming aperture array disposed between the charged particle source and the focusing lens.

36. The first aperture array according to any one of claims 34 and 35, further comprising an on-axis aperture configured to generate an on-axis primary beamlet incident on the on-axis aperture of the second aperture array.

37. A first hole array according to claim 36, wherein the on-axis holes are substantially circular.

38. A first aperture array according to any one of claims 34 to 37, wherein the plurality of off-axis aperture sets are configured to generate a plurality of off-axis beamlets that are incident on corresponding off-axis apertures in the second aperture array.

39. A first array of holes according to any one of claims 34 to 38, wherein a set of the plurality of sets of off-axis holes comprises holes arranged along a tortuous path.

40. A first array of holes according to any one of claims 34 to 39, wherein a set in the plurality of sets of off-axis holes comprises at least two holes having different sizes.

41. A first array of apertures according to any one of claims 34 to 40, wherein a set of the plurality of sets of off-axis apertures comprises apertures sized to determine a current of a corresponding primary beamlet.

42. A first array of holes according to any one of claims 34 to 41, wherein a set in the plurality of sets of off-axis holes comprises holes having uniform spacing.

43. A first array of holes according to any one of claims 34 to 41, wherein a set in the plurality of sets of off-axis holes comprises holes having non-uniform spacing.

44. A first aperture array according to any one of claims 34 to 43, wherein the plurality of off-axis aperture sets comprises apertures having circular, rectangular, elliptical or polygonal cross-sections.

45. A method for observing a sample using a multi-beam device, the method comprising: activating a charged particle source to generate a primary charged particle beam; generating a plurality of primary beamlets from a primary charged particle beam using a first aperture array; generating, using a second aperture array, a plurality of probe beamlets corresponding to the plurality of primary beamlets; adjusting the position of the plane of the condenser lens with respect to the first array of apertures and the second array of apertures along the primary optical axis; as well as generating a plurality of detection spots incident on the sample surface from the plurality of detection beamlets, wherein a probe beamlet of the plurality of probe beamlets is associated with a set of apertures of a first aperture array, and The apertures in the set of apertures in which the detection beamlets are formed are determined at least based on the properties of the condenser lens.

46. ​​A method according to claim 45, wherein adjusting the position of the plane of the focusing lens modifies the characteristics of the detection sub-beams.

47. A method according to any one of claims 45 and 46, wherein adjusting the position of the plane of the condenser lens modifies the current of the detection beamlets.

48. A method according to any one of claims 45 to 47, wherein generating a plurality of primary beamlets comprises: On-axis primary beamlets and off-axis primary beamlets are generated.

49. The method according to claim 48, further comprising: The off-axis primary beamlets are formed into corresponding probe beamlets of the plurality of probe beamlets using a condenser lens.

50. A non-transitory computer readable medium storing a set of instructions executable by one or more processors of a multi-beam device having a first array of apertures and a second array of apertures to cause the multi-beam device to perform a method comprising: activating a charged particle source to generate a primary charged particle beam; as well as The position of the plane of the condenser lens is adjusted along the primary optical axis with respect to the first array of holes and the second array of holes, wherein: The first aperture array is configured to generate a plurality of primary beamlets from the primary charged particle beam using a plurality of aperture sets, A primary beamlet of the plurality of primary beamlets forms a corresponding detection beamlet, and The apertures in the set of apertures forming the detection beamlets are determined based at least on the properties of the condenser lens.

51. A charged particle beam apparatus comprising: a first aperture array, the first aperture array comprising a first plurality of apertures, the first plurality of apertures being configured to form a plurality of primary beamlets from a primary charged particle beam, the apertures in the first plurality of apertures comprising: a first aperture plate configured to be at a first voltage; and A second aperture plate is configured to be at a second voltage different from the first voltage to generate an electric field that enables adjustment of the paths of the charged particles of the primary charged particle beam.

52. The apparatus of claim 51, further comprising: A third aperture plate is configured to be at a third voltage substantially similar to the first voltage.

53. The apparatus according to any one of claims 51 and 52, further comprising: a condenser lens including a flat surface that can be adjusted along a primary optical axis; as well as a second aperture array comprising a second plurality of apertures configured to generate a plurality of detection beamlets, Each of the plurality of detection beamlets comprises a portion of charged particles of a corresponding primary beamlet, and the portion of charged particles is based at least on a position of a plane of the condenser lens and a characteristic of the second aperture array.

54. An apparatus according to any one of claims 52 and 53, wherein the first voltage and the third voltage comprise a reference voltage.

55. Apparatus according to any one of claims 51 to 54, wherein the second aperture plate comprises a charged particle beam deflector configured to adjust the path of the charged particles in response to electrical activation.

56. Apparatus according to claim 55, wherein the charged particle beam deflector comprises a monopole deflector or a multipole deflector.

57. An apparatus according to any one of claims 55 and 56, wherein electrical activation of the second aperture plate comprises a voltage signal being applied to generate an electric field.

58. The apparatus of claim 57, wherein the path of the charged particles is adjusted based on characteristics of a voltage signal applied to the second aperture plate.

59. The apparatus of claim 58, wherein the characteristic of the voltage signal comprises polarity or amplitude.

60. The apparatus of any one of claims 52 to 59, wherein the holes in the first plurality of holes comprise: a first well in a first well plate; a second hole in a second hole plate; as well as The third hole in the third hole plate, wherein the second orifice plate is disposed between the first orifice plate and the third orifice plate, and The geometric centers of the first hole, the second hole and the third hole are aligned.

61. The apparatus of claim 60, wherein the first aperture and the second aperture are different in size, and wherein the first aperture and the third aperture are substantially similar in size.

62. Apparatus according to any one of claims 60 to 61, wherein the third aperture plate is configured to block a portion of the charged particles from leaving the second aperture.

63. Apparatus according to any one of claims 53 to 62, wherein the first array of apertures comprises an array of pre-beamlet forming apertures arranged between the charged particle source and the focusing lens.

64. Apparatus according to any one of claims 53 to 63, wherein the first array of apertures comprises on-axis apertures configured to generate on-axis beamlets which are incident on on-axis apertures of the second array of apertures.

65. Apparatus according to any one of claims 53 to 64, wherein the first array of apertures comprises off-axis apertures configured to generate off-axis beamlets which are incident on corresponding off-axis apertures of the second array of apertures.

66. The apparatus of claim 65, wherein the off-axis apertures of the first array of apertures comprise elongated apertures having rounded ends and tapering widths.

67. The apparatus of claim 66, wherein the off-axis holes of the first array of holes have a curved form.

68. Apparatus according to any one of claims 65 to 67, wherein the off-axis aperture is oriented such that the width tapers towards the primary optical axis.

69. An apparatus according to any one of claims 65 to 68, wherein the focusing lens is configured to cause a portion of the off-axis beamlets to form a corresponding detection beamlet of the plurality of detection beamlets.

70. Apparatus according to any one of claims 53 to 69, wherein the second aperture array comprises a beam limiting aperture array arranged between the focusing lens and the objective lens.

71. An apparatus according to any one of claims 53 to 70, wherein the second plurality of apertures is configured to determine the size and shape of the plurality of detection beamlets.

72. An apparatus according to any one of claims 53 to 71, wherein the characteristics of the second array of holes include at least one of the size, shape and arrangement of the second plurality of holes.

73. An apparatus according to any one of claims 53 to 72, wherein the focusing lens comprises an electrostatic lens, an electromagnetic lens or an electromagnetic compound lens.

74. Apparatus according to any one of claims 51 to 73, wherein the first plurality of holes comprises a plurality of off-axis holes.

75. The apparatus of claim 74, wherein the plurality of off-axis holes comprises a first off-axis hole overlapping a second off-axis hole, wherein the first off-axis hole enables the second hole array to generate a first off-axis detection beamlet, and the second off-axis hole enables the second hole array to generate a second off-axis detection beamlet.

76. An apparatus according to any one of claims 74 to 75, wherein each off-axis hole in the plurality of off-axis holes of the first hole array is separated by a substrate material of the first hole array.

77. Apparatus according to any one of claims 64 to 76, wherein the on-axis holes of the first array of holes are substantially circular.

78. An apparatus according to any one of claims 65 to 77, wherein the area of ​​the on-axis holes of the first array of holes is substantially similar to the area of ​​the off-axis holes.

79. A method for observing a sample using a charged particle beam apparatus, the method comprising: activating a charged particle source to generate a primary charged particle beam; generating a plurality of primary beamlets from a primary charged particle beam using a first aperture plate and a second aperture plate of a first aperture array, wherein the first aperture plate is operated at a first voltage and the second aperture plate is operated at a second voltage different from the first voltage for adjusting a path of the charged particles exiting the first aperture plate; generating, using the second aperture array, a plurality of probe beamlets corresponding to the plurality of primary beamlets; and A plurality of detection spots incident on the sample surface are generated from the plurality of detection beamlets.

80. The method according to claim 79, further comprising: The third aperture plate is operated at a third voltage substantially similar to the first voltage, wherein the first voltage and the third voltage comprise a reference voltage.

81. The method according to any one of claims 79 and 80, further comprising: By electrically activating the second aperture plate, the path of the charged particles is adjusted.

82. The method of claim 81, wherein electrically activating the second aperture plate comprises: A voltage signal is applied to generate an electric field.

83. A method according to any one of claims 79 to 82, further comprising: The position of the plane of the condenser lens is adjusted along the primary optical axis with respect to the first array of apertures and the second array of apertures.

84. A method according to claim 83, wherein adjusting the position of the plane of the focusing lens modifies the characteristics of the plurality of detection beamlets.

85. A method according to any one of claims 83 and 84, wherein adjusting the position of the plane of the focusing lens modifies the current of the plurality of detection beamlets.

86. A method according to any one of claims 79 to 85, wherein generating a plurality of primary beamlets comprises generating on-axis beamlets and off-axis beamlets.

87. A method according to any one of claims 83 to 86, further comprising: Using a condenser lens, a portion of the off-axis beamlets is caused to form a corresponding probe beamlet of the plurality of probe beamlets.

88. A non-transitory computer readable medium storing a set of instructions executable by one or more processors of a multi-beam device having a first array of apertures and a second array of apertures to cause the multi-beam device to perform a method comprising: activating a charged particle source to generate a primary charged particle beam; generating a plurality of primary beamlets from a primary charged particle beam using a first aperture plate and a second aperture plate of a first aperture array, wherein the first aperture plate and the third aperture plate are operated substantially at a first voltage, and the second aperture plate is operated at a second voltage different from the first voltage for adjusting a path of the charged particles exiting the first aperture plate; generating, using the second aperture array, a plurality of probe beamlets corresponding to the plurality of primary beamlets; and A plurality of detection spots incident on the sample surface are generated from the plurality of detection beamlets.

89. A charged particle beam apparatus comprising: a first aperture array, the first aperture array comprising a first plurality of apertures, the first plurality of apertures being configured to form a plurality of primary beamlets from a primary charged particle beam, the apertures in the first plurality of apertures comprising: a first aperture plate configured to be at a first voltage; and a second aperture plate configured to be at a second voltage different from the first voltage for generating an electric field between the first aperture plate and the second aperture plate; and A second aperture array is configured to generate detection beamlets from corresponding primary beamlets, wherein beam currents of the detection beamlets are adjustable.

90. The apparatus of claim 89, wherein the electric field between the first aperture plate and the second aperture plate is substantially fixed.

91. An apparatus according to any one of claims 89 and 90, wherein the beam current is discretely adjusted based on the size of the holes in the first plurality of holes in the first array of holes.

92. The apparatus of claim 89, wherein the electric field between the first aperture plate and the second aperture plate is adjustable.

93. An apparatus according to any one of claims 89 and 92, wherein the beam current is adjusted based on the electric field between the first aperture plate and the second aperture plate.

94. Apparatus according to any one of claims 89 to 93, wherein the electric field is configured to enable adjustment of the path of the charged particles of the primary charged particle beam.

95. Apparatus according to any one of claims 89 to 94, further comprising: A third aperture plate is configured to be at a third voltage substantially similar to the first voltage.

96. The apparatus of claim 95, wherein the first voltage and the third voltage comprise a reference voltage.

97. An apparatus according to any one of claims 94 to 96, wherein the second aperture plate comprises a charged particle beam deflector configured to adjust the path of the charged particles in response to electrical activation.

98. Apparatus according to claim 97, wherein the charged particle beam deflector comprises a monopole deflector or a multipole deflector.

99. An apparatus according to any one of claims 97 and 98, wherein electrical activation of the second aperture plate comprises a voltage signal being applied to generate an electric field.

100. The apparatus of claim 99, wherein the path of the charged particles is adjusted based on characteristics of a voltage signal applied to the second aperture plate.

101. The apparatus of any one of claims 89 to 100, wherein the holes in the first plurality of holes comprise: a first well in a first well plate; a second hole in a second hole plate; as well as The third hole in the third hole plate, wherein the second orifice plate is disposed between the first orifice plate and the third orifice plate, and The geometric centers of the first hole, the second hole and the third hole are aligned.

102. The apparatus of claim 101, wherein the first aperture and the second aperture are different in size, and wherein the first aperture and the third aperture are substantially similar in size.

103. An apparatus according to any one of claims 101 to 102, wherein the third aperture plate is configured to block a portion of the charged particles from leaving the second aperture.

104. An apparatus according to any one of claims 89 to 103, wherein the first array of holes comprises on-axis holes configured to generate on-axis beamlets which are incident on on-axis holes of the second array of holes.

105. An apparatus according to any one of claims 89 to 104, wherein the first array of holes comprises off-axis holes configured to generate off-axis beamlets which are incident on corresponding off-axis holes of the second array of holes.

106. The apparatus of claim 105, wherein the off-axis holes of the first hole array comprise elongated holes having rounded ends and gradually narrowing widths.

107. The apparatus of claim 106, wherein the off-axis holes of the first hole array have a curved form.

108. An apparatus according to any one of claims 105 to 107, wherein the off-axis aperture is oriented so that the width tapers towards the primary optical axis.

109. The apparatus according to any one of claims 105 to 108, further comprising: The condenser lens is configured to cause a portion of the off-axis beamlets to form a corresponding detection beamlet.

110. An apparatus according to claim 109, wherein the second aperture array comprises a beam limiting aperture array disposed between the focusing lens and the objective lens.

111. An apparatus according to any one of claims 89 to 110, wherein the second aperture array comprises a second plurality of apertures configured to generate a plurality of detection beamlets.

112. The apparatus of claim 111, wherein the second plurality of apertures is configured to determine a size and shape of the plurality of detection beamlets.

113. An apparatus according to any one of claims 109 to 112, wherein the detection beamlet comprises a portion of the charged particles of the corresponding primary beamlet based at least on the position of the plane of the focusing lens and the characteristics of the second aperture array.

114. An apparatus according to claim 113, wherein the characteristics of the second hole array include at least one of the size, shape and arrangement of the second plurality of holes.

115. An apparatus according to any one of claims 109 to 114, wherein the focusing lens comprises an electrostatic lens, an electromagnetic lens or an electromagnetic compound lens.

116. The apparatus of any one of claims 89 to 115, wherein the first plurality of holes comprises a plurality of off-axis holes.

117. An apparatus according to claim 116, wherein the plurality of off-axis holes include a first off-axis hole overlapping a second off-axis hole, wherein the first off-axis hole enables the second hole array to generate a first off-axis detection beamlet, and the second off-axis hole enables the second hole array to generate a second off-axis detection beamlet.

118. An apparatus according to any one of claims 116 and 117, wherein each of the multiple off-axis holes of the first hole array is separated by the substrate material of the first hole array.

119. An apparatus according to any one of claims 104 to 118, wherein the on-axis holes of the first hole array are substantially circular.

120. An apparatus according to any one of claims 104 to 119, wherein the area of ​​the on-axis holes of the first hole array is substantially similar to the area of ​​the off-axis holes.

121. A method for observing a sample using a charged particle beam apparatus, the method comprising: activating a charged particle source to generate a primary charged particle beam; generating a plurality of primary beamlets from a primary charged particle beam using a first aperture plate and a second aperture plate of a first aperture array, wherein the first aperture plate is operated at a first voltage and the second aperture plate is operated at a second voltage different from the first voltage to adjust a path of the charged particles exiting the first aperture plate; generating probe beamlets from corresponding primary beamlets using a second aperture array, wherein beam currents of the probe beamlets are adjustable; and A detection spot is generated from the detection beamlets, which is incident on the sample surface.

122. The method of claim 121, wherein adjusting the path of the charged particle comprises: The charged particles are deflected based on an electric field formed between the first aperture plate and the second aperture plate.

123. A method according to claims 121 and 122, wherein the electric field between the first aperture plate and the second aperture plate is substantially fixed, and wherein the beam current of the detection sub-beam is adjusted based on the size of the apertures of the first aperture array.

124. The method of claims 121 and 122, wherein the electric field between the first aperture plate and the second aperture plate is adjustable, and wherein adjusting the beam current of the probe beamlet comprises: The electric field between the first aperture plate and the second aperture plate is adjusted.

125. A method according to any one of claims 122 to 124, wherein deflecting the charged particles is caused by electrically activating the second aperture plate by applying a voltage signal to generate an electric field.

126. The method according to any one of claims 121 to 125, further comprising: The third aperture plate is operated at a third voltage substantially similar to the first voltage, wherein the first voltage and the third voltage comprise a reference voltage.

127. The method according to any one of claims 121 to 126, further comprising: The position of the plane of the condenser lens is adjusted along the primary optical axis with respect to the first array of apertures and the second array of apertures.

128. A method according to claim 127, wherein adjusting the position of the plane of the focusing lens modifies the characteristics of the detection sub-beam.

129. A method according to any one of claims 127 and 128, wherein adjusting the position of the plane of the focusing lens modifies the beam current of the detection sub-beam.

130. The method according to any one of claims 127 to 129, further comprising: Using a condenser lens, a portion of the off-axis primary beamlet is formed into a corresponding detection beamlet.

131. A method according to any one of claims 121 to 130, wherein generating a plurality of primary beamlets comprises: On-axis primary beamlets and off-axis primary beamlets are generated.

132. A non-transitory computer readable medium storing a set of instructions executable by one or more processors of a multi-beam device having a first array of apertures and a second array of apertures to cause the multi-beam device to perform a method comprising: activating a charged particle source to generate a primary charged particle beam; generating a plurality of primary beamlets from a primary charged particle beam using a first aperture plate and a second aperture plate of a first aperture array, wherein the first aperture plate is operated at a first voltage and the second aperture plate is operated at a second voltage different from the first voltage to adjust a path of the charged particles exiting the first aperture plate; generating probe beamlets from corresponding primary beamlets using a second aperture array, wherein beam currents of the probe beamlets are adjustable; and A detection spot is generated from the detection beamlets, which is incident on the sample surface.

133. A charged particle beam device comprising: a pre-beamlet forming aperture set configured to form a plurality of primary beamlets from a primary charged particle beam; as well as a beam-limiting aperture configured to generate a detection beamlet from a corresponding primary beamlet, wherein a beam current of the detection beamlet is determined based on characteristics of an aperture in a set of pre-beamlet-forming apertures forming the primary beamlet, Each aperture in the set of pre-beamlet forming apertures is configured to influence a beam current of a formed detection beamlet.

134. An apparatus according to claim 133, wherein the characteristics of the holes in the pre-beamlet forming hole set include the size, shape or position of the holes.

135. An apparatus according to any one of claims 133 and 134, wherein the beam current of the detection beamlet is discretely adjusted based on the size of the apertures in the set of pre-beamlet forming apertures.

136. Apparatus according to any one of claims 133 to 135, comprising: a first array of a plurality of pre-beamlet forming aperture sets; as well as A second array of a plurality of beam-limiting apertures is arranged downstream of the first array along the primary optical axis of the primary charged-particle beam.

137. An apparatus according to any one of claims 133 to 136, wherein the apertures in the set of pre-beamlet forming apertures that form the detection beamlets are determined based on characteristics of a focusing lens.

138. An apparatus according to claim 137, wherein the characteristics of the focusing lens include the position of the plane of the focusing lens along the primary optical axis.

139. An apparatus according to any one of claims 137 and 138, wherein a change in the position of the plane of the focusing lens is configured to affect the beam current of the detection sub-beam.

140. An apparatus according to any one of claims 137 to 139, wherein the focusing lens is configured to affect the beam current of the detection beamlets by directing parts of the primary charged particle beam through different apertures in the set of pre-beamlet forming apertures.

141. Apparatus according to any one of claims 138 to 140, wherein: A condenser lens located at a first position in the plane is configured to cause a first portion of the primary charged particle beam to pass through a first aperture in the set of pre-beamlet forming apertures to form a first primary beamlet; and The condenser lens located at a second position in the plane is configured to cause a second portion of the primary charged-particle beam to pass through a second aperture in the set of pre-beamlet forming apertures to form a second primary beamlet.

142. Apparatus according to any one of claims 136 to 141, wherein the first array comprises on-axis apertures configured to generate on-axis primary beamlets which are incident on the on-axis apertures of the second array.

143. An apparatus according to any one of claims 136 to 142, wherein the set of pre-beamlet forming apertures comprises a plurality of off-axis pre-beamlet forming apertures configured to generate off-axis primary beamlets which are incident on corresponding off-axis beam limiting apertures in the second array.

144. An apparatus according to claim 143, wherein each of the off-axis pre-beamlet forming apertures is separated by a substrate material of the first array.

145. An apparatus according to any one of claims 143 and 144, wherein the plurality of off-axis pre-beamlet forming apertures are arranged along a curved path.

146. An apparatus according to any one of claims 143 to 145, wherein the plurality of off-axis pre-beamlet forming apertures comprises at least two apertures having different sizes.

147. Apparatus according to any one of claims 143 to 146, wherein the plurality of off-axis pre-beamlet forming apertures are sized to influence beam currents of primary beamlets generated when passing through apertures in the plurality of off-axis pre-beamlet forming apertures.

148. An apparatus according to any one of claims 143 to 147, wherein the holes in the plurality of off-axis pre-beamlet forming holes have uniform spacing.

149. A first array of apertures according to any one of claims 143 to 147, wherein the apertures in the plurality of off-axis pre-beamlet forming apertures have non-uniform spacing.

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