Foil lens corrector, charged particle microscope system including the same, and related methods

Abstract

Foil lens correctors, charged particle microscope systems including foil lens correctors, and related methods. In one example, a foil lens corrector is configured to create a counteracting spherical aberration in a charged particle beam, and includes a graphene foil. In one example, a CPM system includes a charged particle source and a foil lens corrector including a graphene foil. In one example, a method of operating a CPM system includes directing a charged particle beam to a sample; and operating a foil lens corrector to produce a counteracting spherical aberration in the charged particle beam. In one example, the charged particle beam is incident on a foil of the foil lens corrector at a foil incident energy of at least 5 keV, up to 80 keV, and such that the charged particle beam is transmitted through the foil at a transmittance of at least 20%.

Description

Technical Field

[0001] This disclosure generally relates to lens correctors and related methods for correcting spherical aberration in charged particle beams of charged particle microscopy systems. Background Technology

[0002] In the field of charged particle microscopy, when a charged particle microscopy (CPM) system images a sample in scanning probe mode, the resolution of its photomicrograph is related to the minimum diameter of the charged particle beam focused on the sample. In practice, this minimum diameter may be limited by axial optical aberrations, such as spherical aberration, chromatic aberration, and other aberrations introduced into the charged particle beam by the CPM system's optical elements. Specifically, in electromagnetic lens optical systems with static, rotationally symmetric electromagnetic fields and no space charge on the optical axis, non-zero spherical aberration and / or chromatic aberration are unavoidable. Some spherical aberration correctors attempt to correct spherical aberration by introducing multipole electrostatic and magnetic fields, time-varying electromagnetic fields, and / or axial space charge; however, many such previous correction systems suffer from complexity and / or stability issues. Summary of the Invention

[0003] In a representative example, a foil lens corrector for correcting spherical aberration in a charged particle beam generated by a CPM system comprises a foil and an electrode assembly. The foil is configured to align with the optical axis of the CPM system. The electrode assembly is configured to generate a corrector electrostatic potential. The foil comprises graphene and is configured to support space charge such that the optical axis intersects the space charge. The foil lens corrector is configured to generate a corrector electrostatic potential that produces canceling spherical aberration in the charged particle beam to at least partially correct spherical aberration in the charged particle beam.

[0004] In another representative example, the CPM system includes a charged particle source configured to generate a beam of charged particles, and a foil lens corrector for correcting spherical aberration in the charged particle beam. The foil lens corrector includes a foil configured to align with the optical axis of the CPM system and an electrode assembly configured to generate a corrector electrostatic potential. The foil comprises graphene and is configured to support space charge such that the optical axis intersects the space charge. The foil lens corrector is configured such that the corrector electrostatic potential generates canceling spherical aberration in the charged particle beam to at least partially correct spherical aberration in the charged particle beam.

[0005] In another representative example, a method of operating a CPM system including a foil lens corrector includes guiding a charged particle beam along the optical axis to a sample located in the sample plane, and operating the foil lens corrector positioned along the optical axis to generate a corrector electrostatic potential that produces a counteracting spherical aberration in the charged particle beam. Operating the foil lens corrector includes guiding the charged particle beam to a foil of the foil lens corrector such that the charged particle beam is incident on the foil with a foil incident energy of at least 5 keV and at most 80 keV, and that the charged particle beam is transmitted through the foil with a transmittance of at least 20%.

[0006] The foregoing and other objects, features and advantages of the disclosed technology will become more apparent from the following detailed description with reference to the accompanying drawings. Attached Figure Description

[0007] Figure 1 is a schematic diagram of a CPM system based on an example.

[0008] Figure 2A is a schematic cross-sectional view of the foil lens corrector according to the example.

[0009] Figure 2B is a cross-sectional schematic diagram of the area indicated by the dashed circle marked 2B in Figure 2A.

[0010] Figure 3 is a schematic diagram of a CPM system for generating a beam of charged particles with a finite beam convergence angle, based on an example.

[0011] Figure 4 is a diagram illustrating the ray trajectory of a charged particle beam passing through a CPM system according to an example.

[0012] Figure 5A is a graph showing the electrostatic potential amplitude measured along the optical axis of a CPM system according to an example, with the foil lens corrector and the foil operatively mounted in the foil lens corrector.

[0013] Figure 5B is a graph showing the electrostatic potential amplitude measured along the optical axis of a CPM system according to an example, with the foil removed from the foil lens corrector.

[0014] Figure 6 is a graph showing the components of the electrostatic potential amplitude measured along the optical axis of the CPM system within the foil lens corrector according to the example.

[0015] Figure 7A is a turning curve diagram showing the relationship between the first electrode voltage and the second electrode voltage when the spherical aberration coefficient is constant, according to the example.

[0016] Figure 7B is a graph showing the dependence of the third-order spherical aberration coefficients generated by the foil lens corrector in the charged particle beam according to the example on the voltage of the first electrode.

[0017] Figure 7C is a graph showing the dependence of the characteristic beam diameter of the charged particle beam on the voltage of the first electrode, according to the example.

[0018] Figure 7D is a graph showing the dependence of the spherical aberration coefficients on the first electrode voltage according to the example.

[0019] Figure 8 is an image of a graphene foil according to an example.

[0020] Figure 9 is a graph showing the dependence of the charged particle beam transmittance on the foil incident energy of the charged particle beam incident on the foil of the foil lens corrector, according to an example.

[0021] Figure 10 is a cross-sectional view of a foil lens corrector including a corrector housing according to an example.

[0022] Figure 11 is a cross-sectional view of a CPM system including a foil lens corrector and a corrector heater according to an example.

[0023] Figure 12 is a configuration diagram of a portion of the foil lens corrector and corrector heater according to the example, in a disassembled state.

[0024] Figure 13 is a flowchart illustrating the operation method of a CPM system including a foil lens corrector according to an example.

[0025] Figure 14 is a schematic diagram of a computing system that can be used to perform one or more methods of this disclosure, according to an example. Detailed Implementation

[0026] This disclosure generally relates to foil lens correctors for at least partially correcting (e.g., eliminating) at least a portion of spherical aberration in a charged particle beam generated by a CPM system at a focal position, and CPM systems and related methods incorporating such correctors. As described in more detail herein, such foil lens correctors can be used to generate negative spherical aberration in a charged particle beam to counteract positive spherical aberration introduced by the optical elements of the CPM system.

[0027] In many previous CPM designs, spherical aberration and / or chromatic aberration were unavoidable. Specifically, Scherzer's theorem states that positive spherical aberration and chromatic aberration always exist in an electromagnetic lens system that satisfies the following conditions (referred to as the Scherzer conditions in this paper): (1) the electromagnetic field is rotationally symmetric; (2) the electromagnetic field is static; (3) there is no space charge on the optical axis; and (4) the beam of charged particles traveling along the optical axis does not change direction (e.g., opposite to that of an electron mirror).

[0028] Previous CPM systems have attempted to violate one or more of these conditions to eliminate spherical aberration and / or chromatic aberration. For example, various transmission electron microscopes (TEMs) employ multipolar symmetry systems that violate the first Scherzer condition. However, such designs generally suffer from complexity and / or stability issues.

[0029] Previous CPM systems have attempted to violate the third Scherzer condition by introducing conductive foils into the charged particle beam path. However, such foils effectively limit the beam current at the sample due to the relatively low transmittance of the charged particle beam.

[0030] As will be described in more detail below, the foil lens corrector according to this disclosure overcomes these shortcomings of previous systems by using a simple structure that provides high transmittance of charged particle beams and allows correction of spherical aberrations with a small number of degrees of freedom of control. Specifically, in various examples, the foil lens corrector comprises a graphene foil that acts to violate the third Scherzer condition while allowing charged particle beams to pass through the foil with high transmittance.

[0031] Figure 1 is a schematic cross-sectional view of an example CPM system 100 according to the present disclosure. The CPM system 100 may include a charged particle source module 120 with a charged particle source 122, a sample holder 110 configured to hold a sample 112, and a beam guiding system 130. The charged particle source 122 may generate and / or emit a charged particle beam 124 toward the sample 112 along an optical axis 102, while the beam guiding system 130 may shape, modulate, focus, and / or guide the charged particle beam 124 toward the sample 112. As shown in Figure 1, the CPM system includes a foil lens corrector 170 for at least partially correcting spherical aberration in the charged particle beam 124.

[0032] In this disclosure, for clarity, various components of the CPM system and / or foil lens corrector are shown in cross-section. Generally, it should be understood that the illustrated structures extend entirely around an axis of symmetry, such as the illustrated optical axis, in a manner appropriate for rotational symmetry. For example, it should be understood that Figure 1 shows a cross-sectional view of a structure in which the foil lens corrector 170 extends circumferentially entirely around the optical axis 102.

[0033] CPM system 100 can represent an example of any of various CPM systems. Specifically, this disclosure generally relates to examples where CPM system 100 comprises and / or is a SEM system, and / or wherein the charged particle beam 124 is an electron beam 124 guided and focused onto a sample 112 by a beam guiding system 130. In such examples, the (focused) electron beam 124 can interact with the sample 112, causing various types of "stimulated" radiation to be emitted from the sample 112, including, for example, secondary electrons, backscattered electrons, X-rays, and / or photoradiation (catholuminescence). In the example where the charged particle beam 124 is an electron beam 124, the charged particle source 122 may also be referred to as an electron source and / or electron emitter.

[0034] While this disclosure generally relates to CPM system 100 as an example of a SEM system, this is not a requirement for all examples, and within the scope of this disclosure, the systems and apparatus disclosed herein can be used in conjunction with any suitable CPM configuration, such as transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and any suitable combination thereof.

[0035] The charged particle source module 120 and / or beam guiding system 130 may include any of a variety of components and / or elements for operating the charged particle beam 124. For example, as shown in FIG1, the charged particle source module 120 may include an energy selection device 132 configured to limit the energy diffusion of the charged particle beam 124 and / or an aperture 134 configured to limit the angular range of the charged particle beam 124.

[0036] In various examples, energy selection device 132 may be configured to at least partially restrict the chromatic aberration of the charged particle beam 124 located downstream of the charged particle source module 120. For example, energy selection device 132 may be configured to transmit only a portion of the charged particle beam 124, characterized in that the charged particle energy is within a selected energy bandwidth. In some examples, energy selection device 132 includes / or a monochromator. In some examples, energy selection device 132 may include an aperture 134. Examples of energy selection devices that can be used in conjunction with the systems and apparatus of this disclosure have been disclosed in U.S. Patent Nos. 7,034,315, 7,999,225, and 9,741,525, the entire disclosures of which are incorporated herein by reference.

[0037] As shown in Figure 1, the beam guiding system 130 may include: a condenser lens assembly 136 configured to manipulate a charged particle beam 124 toward a sample 112, and / or an objective lens assembly 140 having one or more objective lens elements 142 configured to focus the charged particle beam 124 onto the sample 112. The beam guiding system 130 and / or the objective lens assembly 140 may include one or more scanning deflectors 144 configured to deflect the charged particle beam 124, for example, scanning the charged particle beam 124 relative to the surface of the sample 112.

[0038] In various examples, the beam guiding system 130 may, in any suitable combination or alternatively, include an illuminator, objective lens, projection lens, condenser lens, electrostatic / magnetic lens, deflector (e.g., scanning coil), corrector (such as astigmatism correction device), etc. As shown in Figure 1, one or more elements of the charged particle source module 120 may be described as components of the beam guiding system 130.

[0039] As used herein, terms such as “upstream position” and “downstream position” are intended to indicate the direction of propagation relative to the charged particle beam 124. For example, as shown in Figure 1, various components, features, etc., of the CPM system 100 can be described with reference to the upstream position direction 104 and / or the downstream position direction 106. The upstream position direction 104 generally points towards the charged particle source 122 and / or away from the sample holder 110, while the downstream position direction 106 generally points towards the sample holder 110 and / or away from the charged particle source 122.

[0040] In the example of Figure 1, the foil lens corrector 170 is located downstream of the condenser 136 and upstream of the objective lens assembly 140. Therefore, the condenser assembly 136 can be used to center the charged particle beam 124 on the foil lens corrector 170.

[0041] Generally, it may be necessary to position the foil lens corrector 170 upstream of at least a portion of the objective lens assembly 140 (e.g., upstream of the scan deflector 144). Specifically, such a configuration ensures that the foil lens corrector 170 acts on the charged particle beam 124 in a region where the trajectory of the charged particle beam 124 is substantially stationary and / or not deflected by optical elements such as the scan deflector 144.

[0042] Alternatively, positioning the foil lens corrector 170 upstream of the scanning deflector 144 facilitates operation of the CPM system 100 with a wide field of view. For example, such a configuration ensures that the charged particle beam 124 is operatively aligned with the foil lens corrector 170, regardless of any tilting of the charged particle beam 124 caused by the scanning deflector 144. As an example, the CPM system 100 and / or the beam guiding system 130 can be configured to scan the charged particle beam 124 on the surface of the sample 112 to produce a field of view of at least 50 nanometers (nm), at least 100 nm, at least 200 nm, at least 300 nm, up to 500 nm, up to 250 nm, up to 150 nm, and / or up to 75 nm.

[0043] The beam guiding system 130 may also include a booster tube 150 configured to energize the charged particle beam 124 as it passes through the booster tube 150. The booster tube 150 may be maintained at a booster tube voltage, causing it to generate an associated electrostatic field that energizes the charged particle beam 124 within the booster tube 150. As a more specific example, the charged particle beam 124 may be an electron beam, and the booster tube 150 may be maintained at a positive voltage (e.g., approximately 8000 V) to accelerate the electron beam within the booster tube 150.

[0044] Upon exiting the booster tube 150, the electrostatic field generated by the booster tube and extending downstream of the booster tube can decelerate the charged particle beam 124. In this way, the charged particle beam 124 can exit the booster tube 150 with a significantly reduced energy, allowing it to be incident on the sample 112 with a sample incident energy much lower than that within the beam guiding system 130. A smaller sample incident energy (e.g., approximately tens or hundreds of eV) may be necessary to avoid damaging sensitive components of the sample 112, while maintaining the charged particle beam 124 at a relatively high energy within the booster tube 150 can avoid dispersion due to Coulomb interactions and / or charging effects associated with the beam guiding system 130. Alternatively, in this disclosure, the booster tube 150 may be referred to as accelerator tube 150.

[0045] Additional examples of booster tubes that can be used in conjunction with the systems and apparatus of this disclosure are disclosed in U.S. Patent No. 5,146,090, the full disclosure of which is incorporated herein by reference.

[0046] In practice, the sample incident energy of the charged particle beam 124 emitted by the charged particle source 122 can be selected and / or changed by corresponding variations in the accelerating voltage of the charged particle beam 124. Specifically, the sample incident energy of the charged particle beam 124 can be equal to the difference between the accelerating voltage of the charged particle beam 124 at the charged particle source 122 and the bias voltage applied to the sample 112. In some examples, it may be necessary to keep the sample 112 electrically grounded to avoid damaging the sample 112 and / or otherwise interfering with sample analysis. Therefore, in such examples, the incident energy of the charged particle beam 124 may be primarily and / or solely determined by, and / or equal to, the accelerating voltage at which the charged particle source 122 emits the charged particle beam 124. Since the electrostatic field generated by the booster tube 150 is a conservative field, the effect of the booster tube 150 on the incident energy (e.g., relative to the accelerating voltage) is zero (or negligible).

[0047] The CPM system 100 can be configured such that the charged particle beam 124 is incident on the sample 112 at any of a variety of sample incident energies. As an example, the sample incident energy can be: at least 10 eV, at least 50 eV, at least 100 eV, at least 300 eV, at least 500 eV, at least 1000 eV, at least 5000 eV, at least 10 keV, up to 50 keV, up to 30 keV, up to 7000 eV, up to 2000 eV, up to 1500 eV, up to 700 eV, up to 200 eV, up to 70 eV, up to 20 eV, 10-100 eV, 50-500 eV, 100-1000 eV, 300-1500 eV, 500-2000 eV, 1000 eV-30 keV, and / or 5000 eV-50 keV. Generally, at lower sample incident energies, the total aberration of the charged particle beam 124 is likely primarily determined by chromatic aberration effects. Therefore, using foil lens corrector 170 to correct spherical aberration may be particularly suitable for sample incident energy ranges where spherical aberration is more common, such as sample incident energy greater than 1000 eV.

[0048] Objective lens assembly 140 can be used to guide (e.g., converge and / or focus) the charged particle beam 124 to a focal position 114 (e.g., a position on or near the sample 112). Objective lens assembly 140 can be used to focus the charged particle beam 124 by generating one or more electrostatic and / or magnetic fields that deflect the rays of the charged particle beam 124 to a common focal position (e.g., focal position 114). Specifically, objective lens element 142 can be configured to generate a lens electrostatic field and / or a lens magnetic field, each of which can be used to at least partially guide and / or focus the charged particle beam 124 to the focal position 114. In some examples, magnetic focusing can provide enhanced optical properties (e.g., fewer aberrations) for focusing the charged particle beam 124 compared to purely electrostatic focusing.

[0049] Focal position 114 may include, is, and / or corresponds to any location (e.g., a point, a region, a line, a plane, a volume, etc.) where the charged particle beam is sufficiently focused onto sample 112 and / or another component of the CPM system 100 as described herein. As an example, focal position 114 may include and / or be a focal point and / or focal plane associated with objective assembly 140. Therefore, as used herein, focal position 114 may also be referred to as focal point 114 and / or focal plane 114. Furthermore, or alternatively, focal position 114 may correspond to the location of at least a portion of sample 112 in sample plane 116.

[0050] In examples where focal position 114 comprises at least a portion of the focal plane, it should be understood that such a focal plane need not be a perfect plane. For example, the focal plane may be affected by field curvature associated with objective assembly 140. In some examples, focal position 114 may also, or alternatively, correspond to a location where the charged particle beam 124 exhibits the smallest diameter and / or the smallest degree of optical aberration (e.g., a location along optical axis 102).

[0051] The CPM system 100 may include one or more electron and / or photon detectors configured to detect electrons emitted from the sample 112. For example, as shown in FIG1, the CPM system 100 may include a secondary electron detector 160 configured to detect secondary electrons emitted from the sample 112 and / or a backscattered electron detector 162 configured to detect backscattered electrons. In some examples, as shown in FIG1, the secondary electron detector 160 and / or the backscattered electron detector 162 may be placed inside the optical tube (e.g., inside the booster tube 150). In some examples, the positive electrostatic potential field associated with the booster tube 150 may accelerate electrons toward the secondary electron detector 160 and / or the backscattered electron detector 162 within the booster tube 150.

[0052] Measurements characterizing electrons incident on the secondary electron detector 160 and / or the backscattered electron detector 162 (e.g., characterizing the intensity and / or energy of such detected electrons) can provide indications of various physical properties of the sample 112, such as the geometry of the sample 112 and / or the chemical composition of the sample 112 at the location where the charged particle beam 124 is incident on the sample 112 (e.g., at the focal position 114). Therefore, such measurements can be used to form an image (e.g., a graphical representation) of the sample at the focal position. Thus, the CPM system 100 can characterize the spatial resolution of the sample 112 based at least in part on the minimum size (e.g., minimum diameter) of the charged particle beam 124 at the focal position 114 and / or in the sample plane 116.

[0053] Therefore, by scanning the surface of sample 112 with the charged particle beam 124, an image and / or other representation of sample 112 within the scanning area can be generated. Such scanning can be performed in any suitable manner. For example, a scanning deflector 144 can be used to deflect the charged particle beam 124, causing the charged particle beam 124 to scan the sample 112, and / or to move the focal position 114 relative to sample 112. Alternatively, the sample holder 110 can be configured to rotate and / or translate sample 112 in one or more dimensions to move sample 112 relative to focal position 114. Moving (e.g., translating) sample 112 and / or scanning the charged particle beam 124 in this manner allows selected portions of sample 112 to be irradiated / imaged / examined by the charged particle beam 124 traveling along optical axis 102.

[0054] As shown in Figure 1, the foil lens corrector 170 includes a foil 172 aligned with the optical axis 102 and an electrode assembly 174 configured to generate a corrector electrostatic potential, which is at least substantially confined to one side of the foil 172 (e.g., the upstream or downstream side of the foil 172). The corrector electrostatic potential can act as a lens on the charged particle beam 124 to adjust the spherical aberration of the charged particle beam 124 in a manner as described herein.

[0055] As will be described in more detail below, foil 172 can be used to shape and / or limit the electrostatic potential of the corrector. Specifically, foil 172 can serve as a conductive surface and / or region carrying space charge extending to and / or surrounding the optical axis 102. In this way, foil 172 can violate the third Scherzer condition described above, thereby allowing (in principle) elimination of spherical aberration in the charged particle beam 124.

[0056] In various examples, it may be necessary to configure foil 172 to have high conductivity to support the free flow of charge and / or prevent foil 172 from becoming charged. It may also be necessary to configure foil 172 such that foil 172 itself does not significantly interact with and / or affect the trajectory of the charged particle beam 124, for example, through scattering interactions. Therefore, in various examples according to this disclosure, foil 172 comprises and / or is itself a graphene foil, which can provide high conductivity and a low degree of interaction with the charged particle beam 124. Thus, configuring foil 172 in this way allows foil 172 to be at least substantially transparent to the charged particles (e.g., electrons) of the charged particle beam 124.

[0057] In various examples, foil 172 may contain and / or be a single layer of graphene, a two-layer graphene, a three-layer graphene, or more than three layers of graphene. Generally speaking, the fewer the number of layers in a graphene foil (i.e., the fewer the number of carbon atom layers), the more charged particles may penetrate the foil, but correspondingly, it may be more difficult to prepare and / or process.

[0058] While this disclosure generally relates to examples of foil 172 comprising and / or graphene foil, this is not a requirement for all examples, and within the scope of this disclosure, foil 172 may be made of any suitable material. As an additional example, foil 172 may comprise and / or be a foil of molybdenum disulfide, tungsten disulfide, and / or any other material that provides high planarity, conductivity, and / or transmission of charged particle beams.

[0059] As used herein, the term "foil" refers to any form of material and / or structure characterized by a thickness that is sufficiently small relative to its length and width dimensions to be well approximated as a two-dimensional structure. For example, a foil can be characterized by its length and / or width dimensions that are at least 10,000 times, at least 100,000 times, and / or at least 1,000,000 times larger than its thickness dimension. Alternatively, a foil can be characterized by its thickness, which remains constant over a region of the foil, varying within 75%, 50%, and / or 25% of its maximum thickness.

[0060] Alternatively, the uniformity of the material composition and / or its form can be used to characterize the foil (e.g., a graphene foil). For example, a graphene foil may contain inhomogeneities existing in the form of different carbon allotropes, the thickness of which varies relative to the thickness of the graphene portion of the foil. If such inhomogeneities are sufficiently sparse, then such inhomogeneities are likely to be at least substantially harmless to the function of the foil lens corrector 170 containing such a foil. Thus, in various examples, the foil 172 is characterized by its inhomogeneity density, defined as the proportion of the area of ​​the foil 172 occupied by material inhomogeneities, which is at most 2%, at most 1%, and / or at most 0.1%.

[0061] The foil lens corrector 170 and / or the corrector electrostatic potential can be configured to produce negative spherical aberration in the charged particle beam 124 when the charged particle beam 124 passes through the foil lens corrector 170. Specifically, the negative spherical aberration produced by the foil lens corrector 170 can be configured to counteract positive spherical aberration introduced by other optical elements of the CPM system 100. As a more specific example, the negative spherical aberration produced by the foil lens corrector 170 can be characterized by a third-order spherical aberration coefficient at the sample plane 116, which is at least -20 mm, at least -15 mm, at least -10 mm, at least -5 mm, at least -1 mm, at most 0 mm, at most -2 mm, at most -7 mm, at most -12 mm, and / or at most -17 mm.

[0062] Alternatively, the foil lens corrector 170 and / or the corrector electrostatic potential can be configured to produce positive spherical aberration in the charged particle beam 124 when the charged particle beam 124 passes through the foil lens corrector 170. Specifically, the positive spherical aberration produced by the foil lens corrector 170 can be configured to counteract negative spherical aberration introduced by other optical elements of the CPM system 100. As a more specific example, the negative spherical aberration produced by the foil lens corrector 170 can be characterized by a third-order spherical aberration coefficient at the sample plane 116, which is at least 0 mm, at least 2 mm, at least 7 mm, at least 12 mm, at least 17 mm, up to 20 mm, up to 15 mm, up to 10 mm, up to 5 mm, and / or up to 1 mm.

[0063] In this manner, the foil lens corrector 170 can be used to cancel any one or both of the positive and / or negative spherical aberrations generated in the charged particle beam 124 by one or more other optical elements of the CPM system 100. Therefore, the CPM system 100 can be used to focus the charged particle beam 124 to a focal position 114, and the spherical aberration is negligible and / or zero. As an example, the CPM system 100 can be used to focus the charged particle beam 124 such that the charged particle beam 124 has spherical aberration in the sample plane 116, characterized by third-order spherical aberration coefficients with magnitudes of up to 5 mm, up to 3 mm, up to 1 mm, up to 0.5 mm, and / or 0 mm.

[0064] Generally, the (negative or positive) spherical aberration generated by the foil lens corrector 170 in the charged particle beam 124 can be referred to as canceling spherical aberration. Therefore, canceling spherical aberration can be characterized by spherical aberration coefficients (e.g., third-order spherical aberration coefficients) that are opposite in sign and at least substantially equal in magnitude to the spherical aberration coefficients characterizing the charged particle beam 124 at the sample plane 116 when the foil lens corrector 170 is removed from the CPM system 100. Generally, in this disclosure, canceling spherical aberration corresponds to the spherical aberration measured in the sample plane 116.

[0065] As shown in Figure 1, the foil lens corrector 170 can be placed inside the booster tube 150 and / or electrically coupled to the booster tube 150 via electrical leads 178, etc. Specifically, in some examples, the foil 172 is electrically coupled to the booster tube 150 via the corrector housing 176 of the foil lens corrector 170, which supports the foil 172. In such examples, the booster tube voltage can be considered as a floating ground level, relative to which the corrector electrostatic potential can be defined and / or measured.

[0066] In some examples, the corrector electrostatic potential can be used to reduce the electrostatic potential amplitude along the optical axis 102 at the location of the foil lens corrector 170 relative to the electrostatic potential amplitude along the optical axis 102 within the booster tube 150, which is located away from the foil lens corrector 170. For example, the booster tube 150 may be configured to accelerate the charged particle beam 124 to an enhanced potential along the optical axis 102 within the booster tube 150, while the foil lens corrector 170 may be configured such that the total electrostatic potential amplitude along the optical axis 102 within the foil lens corrector 170 is less than the amplitude of the enhanced potential. The enhanced potential may be related to the booster tube voltage (e.g., at least substantially equal to the booster tube voltage), and / or related to the sum of the booster tube voltage and the energy of the charged particle beam 124 as it exits the charged particle source module 120. As a more specific example, the enhanced potential can be at least 4 keV, at least 6 keV, at least 8 keV, at least 10 keV, at least 12 keV, up to 14 keV, up to 11 keV, up to 9 keV, up to 7 keV, up to 5 keV, 4-9 keV, 6-11 keV, 8-14 keV, and / or 4-14 keV.

[0067] As shown in Figure 1, the CPM system 100 may also include a controller 180, which is programmed and / or otherwise configured to at least partially control the operation of the CPM system 100. For example, the controller 180 may at least partially control the operation of the charged particle source 122 to generate a charged particle beam 124 and / or at least partially control the operation of at least a portion of the beam guiding system 130. Alternatively, the controller 180 may receive signals representing electrons emitted from the surface of the sample 112 from the secondary electron detector 160 and / or the backscattered electron detector 162, which can be used to generate an image and / or other representation of the sample 112.

[0068] In some examples, controller 180 may also at least partially control the operation of foil lens corrector 170 and / or associated systems, for example, by selectively and / or dynamically controlling the booster voltage, selectively and dynamically changing the booster voltage and / or the voltage supplied to electrode assembly 174 to generate corrector electrostatic potential. This can be achieved by regulating one or more electrical signals (e.g., voltages) supplied to CPM system 100 and / or foil lens corrector 170.

[0069] For example, as shown in Figure 1, the controller 180 may include a booster voltage source 182 configured to apply a booster voltage to the booster 150. Specifically, the booster voltage source 182 may be configured to transmit a booster electrical signal 183 to the booster 150, thereby applying a booster voltage to the booster 150.

[0070] Alternatively, controller 180 may include one or more voltage sources configured to provide one or more electrical signals to foil lens corrector 170, such as applying one or more corresponding voltages to various components of foil lens corrector 170, as described herein. Specifically, as shown in FIG1, controller 180 may include a first electrode voltage source 184 configured to transmit a first electrode electrical signal 185 to electrode assembly 174 and / or a second electrode voltage source 186 configured to transmit a second electrode electrical signal 187 to electrode assembly 174.

[0071] As described herein, controller 180 may be programmed and / or configured to control and / or change booster electrical signal 183, first electrode electrical signal 185 and / or second electrode electrical signal 187 to at least partially control the operation of foil lens corrector 170, for example, to adjust the counteracting spherical aberration produced by foil lens corrector 170 in charged particle beam 124.

[0072] As shown in Figure 1, the controller 180 may include a user interface 190 for receiving input from a human user and / or for recording and / or displaying information. Specifically, the user interface 190 may include one or more input devices 192 and / or one or more output devices 194. The one or more input devices 192 may include and / or may be any suitable device for receiving input from a human user to at least partially guide the operation of the CPM system 100, such as a keyboard, mouse, monitor, touchscreen, etc. The one or more output devices 194 may include and / or may be any suitable device for transmitting information to a human user, such as a monitor, touchscreen, physical memory, etc.

[0073] Controller 180 may contain any of a variety of modules (e.g., hardware and / or software) for performing these and other functions. In some examples, controller 180 is a single device containing each of the constituent components described herein. In other examples, controller 180 may refer to and / or contain a set of components that may be at least partially spatially separated. Controller 180 may be connected to any other suitable component of CPM system 100 in any suitable manner, such as via one or more control lines and / or via a wireless connection. As an example, such control lines may include and / or be physical signal conduits such as wires, electrical buses, optical fibers, etc.

[0074] Figures 2A and 2B show an example of the components of a foil lens corrector 200, which may represent an example of the foil lens corrector 170 of Figure 1. Specifically, Figure 2B is a detailed view of the area indicated by the dashed circle in Figure 2A. The foil lens corrector 200 shown in the figure is located within the booster tube 204.

[0075] As shown in Figure 2A, the foil lens corrector 200 includes a first shielding electrode 210 and a second shielding electrode 220 supporting a foil 250, and an electrode assembly 230 located between the first shielding electrode 210 and the second shielding electrode 220. The electrode assembly 230 includes a first electrode 232 and a second electrode 236 located on the common side (i.e., the same side; in this example, the upstream position side) of the foil 250. In this example, the foil 250 spans and / or covers the foil aperture 212 defined in the first shielding electrode 210.

[0076] In this disclosure, if the names of structures, components, and / or features are similar or identical to those previously introduced in different figures, it should be understood as more specific and / or alternative examples of the previously introduced structures, components, and / or features. Therefore, such structures, components, and / or features may have any appropriate characteristics, even if such features are not specifically discussed with reference to the respective figures. As an example, the booster tube 204 in Figure 2A can be described as representative of... Figure 1 An example of the booster tube 150, and can share any suitable characteristics, features, etc. with the booster tube 150.

[0077] Figure 2A also illustrates an example of a corrector electrostatic potential 206 that can be generated by electrode assembly 230. Specifically, in the example of Figure 2A, the corrector electrostatic potential 206 is represented by equipotential lines characterizing the configuration of the corrector electrostatic potential 206. Electrode assembly 230 can be used to generate the corrector electrostatic potential 206 by applying a first electrode voltage to a first electrode 232 (e.g., via the first electrode signal 185 of Figure 1) and a second electrode voltage to a second electrode 236 (e.g., via the second electrode signal 187 of Figure 1). Thus, the first electrode voltage and the second electrode voltage represent two independent degrees of freedom through which the corrector electrostatic potential 206 can be configured, as will be described in more detail below.

[0078] As shown in Figure 2A, electrode assembly 230 is configured to generate a corrector electrostatic potential 206 on a first side 252 of foil 250. The foil lens corrector 200 may also be configured to confine the corrector electrostatic potential 206 to the first side 252 of foil 250. For example, foil 250 and / or the first shielding electrode 210 may be used to shield the corrector electrostatic potential 206 from extending to a second side 254 of the foil opposite the first side 252.

[0079] As a more specific example, foil 250 may be configured to shield the corrector electrostatic potential such that the maximum amplitude of the corrector electrostatic potential 206 on the second side 254 of foil 250 is at most 1% of the maximum amplitude of the corrector electrostatic potential 206 on the first side of foil 250. In such examples, the maximum amplitude of the corrector electrostatic potential 206 on each side of foil 250 may correspond to and / or refer to the amplitude at a certain location along optical axis 202. In this way, foil 250 may be described as limiting and / or preventing the corrector electrostatic potential 206 from extending through foil aperture 212, thereby avoiding, for example, the introduction of aperture lensing effects.

[0080] In the example of Figure 2A, the first side 252 of the foil 250 corresponds to the upstream position side of the foil 250, while the second side 254 of the foil 250 corresponds to the downstream position side of the foil 250. However, this is not a requirement for all examples, and within the scope of this disclosure, the first side 252 of the foil 250 may correspond to the downstream position side of the foil 250. In such examples, each of the first electrode 232 and the second electrode 236 may be placed on the downstream position side of the foil 250, such that the electrode assembly 230 generates a corrector electrostatic potential 206 on the downstream position side of the foil. Therefore, while this disclosure generally relates to examples where the electrode assembly 230 is placed on the upstream position side of the foil 250, it should be understood that the opposite configuration is also within the scope of this disclosure.

[0081] Figure 2B illustrates one way in which the foil 250 is supported in the foil lens corrector 200. As shown in Figure 2B, the first shielding electrode 210 may include a foil aperture 212 (e.g., a circular aperture) such that the foil 250 is coupled to the first shielding electrode 210 and covers (e.g., completely covers) the foil aperture 212.

[0082] As shown in Figure 2B, the first shielding electrode 210 is configured such that the optical axis 202 (and the corresponding charged particle beam) extends through the foil aperture 212 and thus through the foil 250 covering the foil aperture 212. As shown in Figure 2A, the second shielding electrode 220 may include a second aperture 222 axially aligned with the foil aperture 212 along the optical axis 202. Similarly, the first electrode 232 may have a first electrode aperture 234, and the second electrode 236 may have a second electrode aperture 238 additionally aligned along the optical axis 202. Any of the first shielding electrode 210, the second shielding electrode 220, the first electrode 232, and / or the second electrode 236 may extend completely around the optical axis 202.

[0083] As shown in Figure 2B, the foil aperture 212 can be characterized by the foil aperture diameter 214, while the foil 250 can be characterized by the foil diameter 256. In the example of Figure 2B, the foil diameter 256 is larger than the foil aperture diameter 214, such that the foil 250 completely covers the foil aperture 212. When the foil aperture 212 and / or the foil 250 are not perfectly circular, the foil aperture diameter 214 and / or the foil diameter 256 can correspond to any suitable linear dimension, such as the minimum diameter, maximum diameter, average diameter, etc. For example, to ensure that the foil 250 completely covers the foil aperture 212, the foil aperture diameter 214 can correspond to the maximum diameter of the foil aperture 212, while the foil diameter 256 can correspond to the minimum diameter of the foil.

[0084] In some examples, the foil aperture 212 can be described as effectively shielding a portion of the foil 250 (e.g., the portion of the foil 250 outside the foil aperture 212) so that it cannot generate a region through which a charged particle beam can pass through the foil lens corrector 200. Therefore, in various examples, the foil aperture diameter 214 can also be referred to as the effective foil diameter 214, which can be described as characterizing the region of the foil 250 through which a charged particle beam can pass. For example, the effective foil diameter 214 may correspond to and / or be equal to the maximum diameter of a charged particle beam that can pass through the foil lens corrector 200. As will be discussed in more detail below, this diameter may be related to other aspects of CPM system operation, such as the beam current delivered to the sample and / or the convergence angle of the charged particle beam. Therefore, in many examples, it is necessary to configure the foil lens corrector 200 and / or the foil 250 to have the largest possible effective foil diameter 214.

[0085] The foil aperture diameter 214 and / or the effective foil diameter 214 can be any of a variety of values, such as corresponding to the linear dimension of the foil 250 and / or the desired maximum diameter of the charged particle beam passing through the foil 250. As an example, the foil aperture diameter 214 and / or the effective foil diameter 214 can be at least 50 micrometers (µm), at least 100 µm, at least 200 µm, at least 300 µm, at least 500 µm, up to 700 µm, up to 400 µm, up to 250 µm, up to 150 µm, and / or up to 75 µm.

[0086] In some examples, the foil 250 may independently span the foil aperture 212. In other words, in such examples, the foil 250 may span the foil aperture 212 without any other direct support, except for the support provided by the peripheral structure of the foil aperture 212. However, this is not necessary, and within the scope of this disclosure, the foil 250 may be supported by a foil support structure 258 that at least partially spans the foil aperture. In such examples, the foil support structure 258 may comprise and / or be any of a variety of structures, such as a mesh (e.g., a TEM mesh), a grid, and / or a perforated structure. The foil support structure 258 may be directly coupled to and / or make direct contact with the foil 250, the foil aperture 212, and / or the first shielding electrode 210. If such a foil support structure 258 is used, a larger foil 250 can be used across a larger foil aperture diameter 214, but this may also lead to increased scattering and / or reduced transmission of charged particle beams through the foil aperture 212.

[0087] Figure 3 illustrates how various dimensions of the foil lens corrector and / or a CPM system incorporating the foil lens corrector can affect various characteristics of the charged particle beam. Specifically, Figure 3 schematically illustrates various aspects of a CPM system 300 incorporating the foil lens corrector 310, wherein the foil 312 is aligned with the optical axis 302 through which the charged particle beam 304 propagates. As shown in Figure 3, the foil lens corrector 310 and / or the foil 312 define an effective foil diameter 314, which therefore represents the maximum diameter of the charged particle beam 304 that can pass through the foil lens corrector 310.

[0088] The CPM system 300 includes a charged particle beam source 340, the emission width of which is at least partially limited by an aperture 342 for a charged particle beam 304. The CPM system 300 also includes an objective lens assembly 320 that focuses the charged particle beam 304 to a focal position 332 within a sample plane 334 associated with the sample 330. The charged particle beam 304 may be characterized by a first beam diameter 306 located upstream of and / or at the objective lens assembly 320. The objective lens assembly 320 may be configured to focus the charged particle beam 304 to a focused beam diameter 308 at the focal position 332.

[0089] Generally, it may be necessary to operate the CPM system 300 to minimize the focused beam diameter 308 of the charged particle beam 304, thereby maximizing the accuracy and / or resolution of the CPM system when targeting the sample region 330. However, as described herein, the minimum achievable focused beam diameter 308 may be limited by various optical aberrations. Therefore, the beam spot pattern of the charged particle beam 304 at the sample plane 334 may always have a non-zero focused beam diameter 308.

[0090] The beam pattern in sample plane 334 may also have uneven intensity and / or lack sharp edges. Therefore, the focused beam diameter 308 can be determined by the diameter d. 50 Characterized as a circle perpendicular to the optical axis 302 and centered at the focal position 332, this circle contains 50% of the charged particles in the charged particle beam. As used herein, the diameter d is defined in this manner... 50 It can also be called the characteristic beam diameter. The focusing beam diameter 308 shown in Figure 3 can represent this characteristic beam diameter, and therefore can also be called the characteristic beam diameter 308.

[0091] The CPM system 300 can be configured such that the charged particle beam 304 has any suitable characteristic beam diameter 308. As an example, the characteristic beam diameter 308 can be at least 0.2 nm, at least 0.5 nm, at least 1 nm, at least 3 nm, at least 5 nm, up to 10 nm, up to 4 nm, up to 2 nm, up to 0.7 nm, up to 0.2 nm, 0.2-1 nm, 0.5-5 nm, and / or 1-10 nm.

[0092] The charged particle beam 304 can also be characterized by a beam convergence angle 322 (or “aperture angle”), which can be measured between the optical axis 302 and the outer range of the envelope of the charged particle beam 304. As shown in Figure 3, the beam convergence angle 322 can be geometrically related to the objective focal length 324, measured axially between the sample plane 334 and the primary objective plane 326 of the objective assembly 320, and the first beam diameter 306 and the focusing beam diameter 308. Specifically, as used herein, the primary objective plane 326 of the objective assembly 320 refers to a plane spatially associated with the objective assembly 320 (e.g., at least partially within the objective assembly 320), from which the objective focal length 324 is measured.

[0093] In various examples, the CPM system 300 needs to be configured with a large aperture angle. For example, the achievable minimum focused beam diameter 308 may be limited by optical aberrations such as spherical aberration and chromatic aberration, as well as diffraction effects. In some examples, the degree of spherical aberration is proportional to the cube of the aperture angle, the degree of chromatic aberration is linearly proportional to the aperture angle, and diffraction effects are inversely proportional to the aperture angle. Therefore, increasing the aperture angle can reduce undesirable diffraction effects but will increase spherical aberration and / or chromatic aberration effects. Thus, these considerations may impose practical limitations on the maximum usable aperture angle. However, when using a foil lens corrector to correct spherical aberration and / or using an energy selection device to limit chromatic aberration, increasing the aperture angle can better control the achievable minimum focused beam diameter 308 by suppressing diffraction effects.

[0094] In practice, the objective lens assembly 320 can be used to adjust the objective focal length 324, which in turn may cause a change in the focusing beam diameter 308. For a given value of the objective focal length 324 (e.g., a value that minimizes the focusing beam diameter 308 under optical aberration constraints), the beam convergence angle 322 can be increased by correspondingly increasing the first beam diameter 306. The first beam diameter 306 may, in turn, be limited by the effective foil diameter 314. Therefore, it may be necessary to increase and / or maximize the effective foil diameter 314 to allow operation at a wide range of beam convergence angles 322.

[0095] Since the effective foil diameter 314 is also related to the maximum flux of the charged particle beam 304 through the foil lens corrector 310, a relatively large effective foil diameter 314 can also enable operation with a wide range of beam currents at the focal position 332. As an example, the CPM system 300 can be configured to guide the charged particle beam 304 to the sample plane 334 with a beam current of one or more of the following: at least 10 picoamperes (pA), at least 30 pA, at least 50 pA, at least 100 pA, at least 300 pA, at least 500 pA, at least 1000 pA, up to 2000 pA, up to 700 pA, up to 400 pA, up to 200 pA, up to 70 pA, up to 40 pA, and / or up to 20 pA.

[0096] Figure 4 is a simplified schematic diagram of a set of ray trajectories 400 associated with a charged particle beam as it travels along the optical axis of a CPM system (e.g., CPM system 100 in Figure 1), with different scales in the horizontal and vertical directions. In Figure 4, the axial positions of the components of the CPM system are indicated by horizontal dashed lines. Specifically, line 410 represents the axial position of the charged particle beam source. Lines 420 and 422 represent the upstream and downstream ends of a foil lens corrector, which acts on ray trajectory 400 to produce negative spherical aberration in the charged particle beam, respectively. Specifically, line 422 may represent the axial position of the foil of the foil lens corrector. Lines 430 and 432 represent the upstream and downstream ends of the objective lens assembly of the CPM system, respectively.

[0097] Figure 4 also illustrates how the beam convergence angle 444, characterizing the charged particle beam downstream of the objective assembly, relates to the characteristics of the foil lens corrector. Specifically, as shown in Figure 4, the beam convergence angle 444 can be geometrically related to the beam width 442 of the charged particle beam as it exits the objective assembly. The beam width 442 can then be related to (e.g., proportionally) the beam width 440 of the charged particle beam as it exits the foil lens corrector. The beam width 440 may be limited by one or more dimensions associated with the foil lens corrector, such as the effective foil diameter described above with reference to Figures 2B and 3. Therefore, configuring the foil lens corrector such that the foil and / or foil aperture is as large as possible can correspondingly increase the maximum beam convergence angle achievable by the CPM system.

[0098] Figures 5A and 5B illustrate how the foil of a foil lens corrector can correct spherical aberrations in a charged particle beam passing through the foil lens corrector. Specifically, Figure 5A shows the axial electrostatic potential curve along the optical axis within the booster tube of a CPM system (e.g., CPM system 100 in Figure 1) in the region containing the foil lens corrector, with the corrector's foil aligned with the optical axis. Figure 5B shows the axial electrostatic potential in the same example as Figure 5A, but with the foil removed from the foil lens corrector.

[0099] In Figures 5A and 5B, the regions corresponding to the axial positions of the foil lens corrector are represented by a pair of vertical dashed lines, where line 510 corresponds to the upstream end of the foil lens corrector (e.g., the second shielding electrode 220 in Figure 2), and line 520 corresponds to the downstream end of the foil lens corrector (e.g., the first shielding electrode 210 and / or the foil aperture 212 in Figure 2). Specifically, Figures 5A and 5B correspond to an example where the foil is configured to be placed at the downstream end of the foil lens corrector.

[0100] As shown in Figures 5A and 5B, in the region shown except for the axial region corresponding to the position of the foil lens corrector, the electrostatic potential amplitude is approximately equal to the booster voltage of 8000 V. In this axial region, the function of the corrector electrostatic potential is to reduce the total electrostatic potential below 8000 V.

[0101] As shown in Figure 5A, when the foil is installed in the foil lens corrector, the potential curve exhibits a sudden "inflection point" 532, where the potential downstream of the foil is essentially equal to the booster voltage. This can be described as reflecting the characteristic of the foil that it effectively shields the corrector's electrostatic potential from extending downstream of the foil lens corrector, thus ensuring that the total potential downstream of the foil lens corrector is only related to the booster. In contrast, in the example of Figure 5B, a portion of the corrector's electrostatic potential extends into the downstream region 530 at the end of the downstream position of the foil lens corrector, thereby reducing the total electrostatic potential in that region to a value less than the booster voltage (e.g., the sum of the positive booster voltage and the negative corrector electrostatic potential).

[0102] The shape of the potential curve at the foil location shown in Figure 5A may be related to the negative spherical aberration generated by the foil lens corrector. For example, the potential curve shown in Figure 5A can be described as exhibiting a significant non-zero third derivative at foil location 520, which in turn may be related to the third-order spherical aberration coefficient associated with the foil lens corrector. The selective configuration of the potential curve upstream of foil location 520, for example by selecting the first electrode voltage and the second electrode voltage, can thus be characterized by adjusting the third-order spherical aberration coefficient and / or higher-order spherical aberration coefficients.

[0103] The potential curve of the foil lens corrector can be used to induce a lensing effect on a charged particle beam in various ways. For example, the foil lens corrector can be configured to act as a converging lens for the charged particle beam. Alternatively, the foil lens corrector can be configured to act as a diverging lens for the charged particle beam.

[0104] Confining the corrector electrostatic potential to the region upstream of the foil can also offer practical benefits for the design of other components in the CPM system. For example, when the corrector electrostatic potential downstream of the foil lens corrector is virtually zero, additional optical and / or other components can be placed within the optical barrel and / or booster tube with negligible risk of interference and / or influence from the corrector electrostatic potential.

[0105] Figure 6 illustrates the area containing the foil lens corrector aligned with the optical axis and the CPM system (e.g., Figure 1 An example set of axial electrostatic potential curves related to the components of the CPM system 100 is shown. Similar to Figures 5A to 5B, the axial region shown in Figure 6 corresponds to the region within the booster tube where the booster tube voltage is maintained, with the foil lens corrector located in the region defined by the vertical dashed lines labeled 602 and 604. The axial position of the vertical dashed line 604 indicates the axial position of the foil of the foil lens corrector.

[0106] The potential curve marked 610 in Figure 6 represents the potential curve generated by the booster tube and has been normalized according to the booster tube voltage value. Therefore, the value of potential curve 610 outside the foil lens corrector is 1. Inside the foil lens corrector, the potential value of potential curve 610 decreases, possibly because one or more elements of the foil lens corrector at least partially shield the optical axis from the booster tube potential. For example, referring to Figure 2A, the first electrode 232 and / or the second electrode 236 can be used to shield the optical axis 202 from the booster tube potential. Similar to Figure 5A, potential curve 610 exhibits an abrupt "inflection point" 612 at the foil location 604, which also corresponds to the shielding behavior of the foil.

[0107] The potential curves labeled 620 and 630 in Figure 6 represent the potential curves generated by the first and second electrodes of the foil lens corrector, respectively. Potential curves 620 and 630 have also been normalized according to the voltage value of the booster tube. In this way, Figure 6 can be described as representing the combination of the individual potential components to form the total potential curve shown in Figure 5A. In other words, Figure 5A can be described as representing the sum of the normalized potential curves 610, 620, and 630 shown in Figure 6. In other words, although Figure 6 presents potential curves 610, 620, and 630 in normalized units, it should be understood that the values ​​shown in Figure 5A represent the sum of the corresponding potentials without such normalization.

[0108] The potential curves 620 and 630 in Figure 6 can be adjusted independently of each other by selecting the corresponding first and second electrode voltages. In this way, the relative and absolute amplitudes of the potential curves 620 and 630 can be adjusted to adjust the lens characteristics of the foil lens corrector on a beam of charged particles propagating along the optical axis.

[0109] Figures 7A through 7D illustrate how the characteristics of the charged particle beam associated with a CPM system (e.g., CPM system 100 of Figure 1) vary with changes in the first and / or second electrode voltages associated with the foil lens corrector of the CPM system. Specifically, the first and second electrode voltages described herein with reference to Figures 7A through 7D can correspond, respectively, to the voltages of the first and second electrodes of the electrode assembly of any suitable foil lens corrector disclosed herein. Figures 7A through 7C correspond to common CPM configurations where the CPM system focuses the charged particle beam to a focal position with an incident energy of 3 keV and a beam current of approximately 80 pA.

[0110] Figure 7A shows an example of a control curve through which the first and second electrode voltages can be varied while the foil lens corrector produces a constant canceling spherical aberration in the charged particle beam. Specifically, the constant canceling spherical aberration produced by the foil lens corrector may be a spherical aberration generated at the sample plane, characterized by a third-order spherical aberration coefficient of zero. In this way, for a given (constant) value of the third-order spherical aberration coefficient C3 characterizing the canceling spherical aberration produced by the foil lens corrector, and at a given value of the second electrode voltage, Figure 7A shows the value of the first electrode voltage that will produce the given value of C3, for example, canceling the spherical aberration at the sample plane. Therefore, Figure 7A illustrates an example of a combination of first and second electrode voltages that can produce a selected value of C3.

[0111] Figure 7B illustrates an example of the relationship between the third-order spherical aberration coefficient C3 and the first electrode voltage when the second electrode voltage is constant. Specifically, in the example of Figure 7B, the second electrode voltage is maintained at 7200 V. Furthermore, in this example, the coefficient C3 represents the total third-order spherical aberration of the charged particle beam at the focal position and / or the sample plane. Therefore, for a given predetermined operating value of the second electrode voltage, the curve shown in Figure 7B can indicate the value of the first electrode voltage that will cause C3 to reach the desired (e.g., sufficiently small) value. In the example of Figure 7B, the total third-order spherical aberration of the charged particle beam reaches zero when the first electrode voltage is approximately 5820 V.

[0112] Figure 7C also shows the characteristic beam diameter d of the charged particle beam when the second electrode voltage is a given value. 50 An example of the dependence on the first electrode voltage. Specifically, in the example of Figure 7C, the second electrode voltage is maintained at 7200 V. As shown in Figure 7C, the feature beam diameter reaches its minimum when the first electrode voltage is approximately 5850 V.

[0113] Minimize the first electrode voltage value of C3 (Figure 7B) and minimize d 50 The differences in the first electrode voltage values ​​(Figure 7C) may be at least partly attributable to the fact that the achievable minimum beam diameter depends not only on third-order spherical aberration but also on chromatic aberration and higher-order spherical aberration. Other factors that may limit the achievable minimum beam diameter include diffraction effects, the size of the charged particle source, etc.

[0114] Figure 7D shows the total spherical aberration C of a charged particle beam focused at the focal position. si An example of the relationship between the first electrode voltage and the CPM system. Figure 7D corresponds to an example of a CPM system focusing a charged particle beam to the focal point, with an incident energy of 10 keV, a beam current of 80 pA, and a second electrode voltage of 5000 V. Under these conditions, as shown in Figure 7D, the total spherical aberration C... si The voltage at the first electrode reaches zero at approximately 5350 V.

[0115] As described above, in various examples, the foil of the foil lens corrector according to this disclosure comprises and / or is a graphene foil. Figure 8 shows an example of a foil 800 in the form of a graphene foil, characterized by a foil diameter 802. The foil diameter 802 shown in Figure 8 may correspond to the diameter of the foil 800 itself, and / or may correspond to the effective foil diameter as described above with reference to Figure 2B.

[0116] In the example of Figure 8, the foil 800 also contains various surface contaminants 810. As will be described in more detail below, in order to minimize the interaction between the foil 800 and the charged particle beam, it may be necessary to minimize the occurrence of contaminants 810 on the foil 800 during the fabrication of the foil 800 and / or remove such contaminants 810 during the operation of the foil lens corrector.

[0117] As mentioned above, the use of graphene foils can provide a high degree of transmittance of charged particle beams through the foil within the operating range of charged particle beam energies. For example, Figure 9 shows the function of transmittance through a three-layer graphene foil as a function of the incident energy of a charged particle beam (e.g., electrons) onto the foil.

[0118] Referring to the CPM system 100 in Figure 1, the foil incident energy can be at least partially based on the booster potential applied to the booster 150. Specifically, the foil incident energy can be at least substantially equal to the sum of the booster potential and the energy of the charged particle beam generated by the beam emitter of the CPM system. Figure 9 thus illustrates the advantages of using a foil lens corrector in conjunction with the booster, as the increased energy of the charged particle beam results in a practically smaller cross-section interacting with the foil material. Figure 9 As shown, when the incident energy of the foil (e.g., the sum of the booster potential and the charged particle source potential) is about 8000 V, the graphene foil can produce a transmittance of about 70%.

[0119] However, this is not a requirement for all examples, and within the scope of this disclosure, the foil incident energy and transmittance can each take any of a variety of values. As an example, the CPM system and / or foil lens corrector can be configured such that the transmittance corresponding to a given operating foil incident energy is at least 5%, at least 10%, at least 20%, at least 30%, at least 50%, at least 70%, at least 80%, up to 95%, up to 75%, up to 60%, up to 40%, up to 25%, up to 15%, and / or up to 7%. Alternatively, the CPM system can be configured such that the incident energy of the operational foil is at least 5 keV, at least 7 keV, at least 10 keV, at least 15 keV, at least 20 keV, at least 30 keV, at least 50 keV, at least 70 keV, up to 80 keV, up to 60 keV, up to 40 keV, up to 25 keV, up to 17 keV, up to 12 keV, up to 8 keV, up to 6 keV, 5-8 keV, 7-12 keV, 5-15 keV, 5-20 keV, 5-30 keV, 5-40 keV, 5-60 keV, and / or 5-80 keV.

[0120] Generally, the transmittance of a graphene foil can also depend on the beam current of the charged particle beam; however, for beam currents in the pA and nA range, the transmittance can be described as effectively depending only on the incident charged particle energy. For a given foil incident energy, the transmittance of a charged particle beam through the foil can increase as the foil thickness (e.g., number of layers) decreases. Constructing a foil lens corrector with only a few layers (e.g., one layer) of graphene can present practical challenges because such graphene foils may be correspondingly difficult to fabricate and / or process.

[0121] Figure 10 illustrates another example of a foil lens corrector 1000 according to the present disclosure, which may also represent an example of the foil lens corrector 170 of Figure 1. Similar to the foil lens corrector 200 of Figure 2, the foil lens corrector 1000 includes a foil 1050 and an electrode assembly 1030, the electrode assembly 1030 including a first electrode 1032 and a second electrode 1036 located on a common side (i.e., the same side) of the foil 1050. In the example of Figure 10, the foil lens corrector 1000 includes a corrector housing 1010 that supports at least a portion of the foil 1050 and / or the electrode assembly 1030. Specifically, in the example of Figure 10, the first electrode 1032 and the second electrode 1036 are contained within the corrector housing 1010.

[0122] Similar to the example in Figure 2, the foil lens corrector 1000 of Figure 10 can be described as including a first shielding electrode 1012 and a second shielding electrode 1014 supporting a foil 1050, such that an electrode assembly 1030 is located between the first shielding electrode 1012 and the second shielding electrode 1014. In the example of Figure 10, the corrector housing 1010 can be described as including the first shielding electrode 1012 and the second shielding electrode 1014, and a housing 1020 extending between the first shielding electrode 1012 and the second shielding electrode 1014. In the example of Figure 10, the housing 1020 is a generally cylindrical wall connecting the first shielding electrode 1012 and the second shielding electrode 1014. As will be discussed in more detail below, the corrector housing 1010 and / or the first shielding electrode 1012 include a housing recess 1070 extending inward toward the electrode assembly 1030.

[0123] The housing 1020 can be directly coupled to and / or in direct contact with the first shielding electrode 1012 and the second shielding electrode 1014 to electrically couple the first shielding electrode 1012 and the second shielding electrode 1014 to each other. Alternatively, the housing 1020 and the first shielding electrode 1012 and / or the second shielding electrode 1014 can be a monolithic structure and / or integrally formed.

[0124] In an example where the first shielding electrode 1012, the second shielding electrode 1014, and the housing 1020 are electrically coupled to each other, such components can be described as representing parts of a single electrode structure that can be maintained at a selected potential during operation of the foil lens corrector 1000. For example, during operation of a CPM system including the foil lens corrector 1000, the entire corrector housing 1010, including the first shielding electrode 1012, the second shielding electrode 1014, and the housing 1020, can be configured to remain at the booster voltage.

[0125] In the example of Figure 10, the calibrator housing 1010 can be configured to limit the extension of the calibrator electrostatic potential beyond the calibrator housing 1010. For example, the first shielding electrode 1012, the second shielding electrode 1014, and / or the housing 1020 can be configured to form the calibrator electrostatic potential within the calibrator housing 1010, and / or at least partially limit the calibrator electrostatic potential (e.g., radially) within the calibrator housing 1010.

[0126] To maintain the first electrode 1032 and the second electrode 1036 at a different potential from the corrector housing 1010, the first electrode 1032 and the second electrode 1036 can be electrically insulated from the corrector housing 1010. Specifically, in the example of FIG. 10, the foil lens corrector 1000 includes an insulating support 1060 that supports the first electrode 1032 and the second electrode 1036 relative to the corrector housing 1010. The insulating support 1060 can be formed of a material with suitable low conductivity to electrically insulate the first electrode 1032 and the second electrode 1036 from the corrector housing 1010.

[0127] Figure 11 illustrates a portion of a CPM system 1100 including a foil lens corrector 1110 according to the present disclosure. The foil lens corrector 1110 of Figure 11 may be at least substantially the same as the foil lens corrector 1000 of Figure 10, and / or may be described as an example representing the foil lens corrector 170 of Figure 1. Referring to the upstream position direction 1104 and the downstream position direction 1106 marked in Figure 11, the foil lens corrector 1110 is configured such that the foil 1150 is located downstream of the first electrode 1122 and the second electrode 1124 of the electrode assembly 1120. Similar to Figure 10, Figure 11The foil lens corrector 1110 further includes a corrector housing 1130 having a first shielding electrode 1132, a second shielding electrode 1134 and a housing 1136, and an insulating support 1138 electrically insulating the first electrode 1122 and the second electrode 1124 from the corrector housing 1130.

[0128] In the example of Figure 11, the CPM system 1100 and / or foil lens corrector 1110 further include a corrector heater 1160 configured to heat the foil 1150 during operation of the CPM system 1100 and / or during operation of the foil lens corrector 1110. The corrector heater 1160 includes a heating element 1162 configured to receive current (e.g., for generating resistive heat energy) and a heater body 1164 configured to transfer heat energy to the foil 1150. The heater body 1164 may include an electrically insulating portion 1166 and a conductive portion 1168. As shown in Figure 11, the heating element 1162, the heater body 1164, and / or the conductive portion 1168 may define at least a portion of a heater conduit 1169 configured to allow a charged particle beam to pass through the corrector heater 1160 and / or the heater body 1164 along the optical axis 1102.

[0129] The calibrator heater 1160 can be configured to heat the foil 1150 in a manner that reduces and / or limits the formation of contaminants on the foil 1150 that could adversely interfere with the transmission of the charged particle beam. For example, during operation of the CPM system 1100, the charged particle beam can break down various carbohydrate substances that may be present in foil defects and / or residual atmosphere, which may subsequently adhere to the foil 1150. By heating the foil 1150 to a temperature of approximately 200°C, such contaminants can be prevented from adhering to the foil 1150 and / or can be removed from the foil 1150.

[0130] In various examples, the electrically insulating portion 1166 of the heater body 1164 is made of a thermally conductive and electrically insulating material, such as aluminum nitride. In this way, the electrically insulating portion 1166 can be used to electrically isolate the heating element 1162 from the foil 1150 and / or the corrector housing 1130. Therefore, the heating element 1162 can be spaced apart from the foil 1150 and the corrector housing 1130. This configuration allows for efficient heat transfer to the foil 1150 (e.g., by conduction) without requiring the heating element 1162 to withstand the high voltages that the foil 1150 and / or the corrector housing 1130 may hold.

[0131] In various examples, the conductive portion 1168 of the heater body 1164 is made of a material that is both electrically and thermally conductive, such as molybdenum. As shown in Figure 11, the conductive portion 1168 may comprise and / or be a tubular element that contacts the foil 1150 and / or the corrector housing 1130 to support the conductive heating of the foil 1150. Therefore, the conductive portion 1168 can maintain the same potential as the foil 1150 and / or the corrector housing 1130, such as the booster tube potential. Configuring the conductive portion 1168 to be conductive facilitates the passage of charged particle beams through the heater conduit 1169 without charging the conductive portion 1168.

[0132] In some examples, as shown in Figure 11, the CPM system 1100 includes a ferromagnetic conduit 1170 located downstream of at least a portion of the heater body 1164 (e.g., downstream of the heater conduit 1169). When present, the ferromagnetic conduit 1170 can be used to at least partially shield the charged particle beam from electromagnetic interference associated with and / or generated by the corrector heater 1160.

[0133] As described above, confining the corrector electrostatic potential generated by the electrode assembly 1120 to a location upstream of the foil 1150 ensures that the lens operation of the foil lens corrector 1110 is not adversely affected by the introduction of the corrector heater 1160. As shown in FIG11, the corrector heater 1160 can therefore be positioned very close to the foil 1150. Specifically, in this example, the first shielding electrode 1132 of the corrector housing 1130 defines a housing recess 1140 that extends toward the electrode assembly 1120 and receives at least a portion (e.g., conductive portion 1168) of the corrector heater 1160 and / or heater body 1164.

[0134] The heater body 1164 can be thermally coupled to the heating element 1162 and / or the foil 1150 in any suitable manner. For example, as shown in FIG11, the electrically insulating portion 1166 of the heater body 1164 can be directly coupled to and / or make direct contact with the heating element 1162, while the conductive portion 1168 of the heater body 1164 can be directly coupled to and / or make direct contact with the electrically insulating portion 1166 and the foil 1150 (and / or the area of ​​the first shielding electrode 1132 near the foil 1150). In such examples, the calibrator heater 1160 can be configured to heat the foil 1150 primarily via conductive heat transfer. In other examples, the heater body 1164 can be spaced apart from the heating element 1162 and / or the calibrator housing 1130. In such examples, the calibrator heater 1160 can be configured to heat the foil 1150 at least partially via radiative heat transfer.

[0135] Figure 12 illustrates an example of a disassembled configuration of the foil lens corrector 1200 and corrector heater 1250. The foil lens corrector 1200 and corrector heater 1250 in Figure 12 may be at least substantially the same as the foil lens corrector 1110 and corrector heater 1160 in Figure 11. For example, as shown in Figure 12, the foil lens corrector 1200 includes a corrector housing 1210 having a first shielding electrode 1220 and a housing 1230 extending from the first shielding electrode 1220. The first shielding electrode 1220 defines a housing recess 1222 configured to receive a portion of the corrector heater 1250. The corrector heater 1250 includes a heating element 1260 and a heater body 1270. The heater body 1270 includes an electrically insulating portion 1272 and a conductive portion 1274. Figure 12 also shows multiple electrical leads 1280, which can be configured to supply power to the heating element 1260 to generate heat.

[0136] Figure 13 is a flowchart illustrating an example of method 1300 for operating a foil lens corrector (e.g., foil lens corrector 170 of Figure 1, foil lens corrector 200 of Figures 2A-2B, foil lens corrector 310 of Figure 3, foil lens corrector 1000 of Figure 10, and / or foil lens corrector 1110 of Figure 11) and / or a CPM system incorporating such foil lens correctors (e.g., CPM system 100 of Figure 1 and / or CPM system 1100 of Figure 11). In the following discussion, various components will be described in conjunction with method 1300, and the terminology used corresponds to the components shown in Figures 1-12 and discussed above. Therefore, these components described herein with reference to method 1300 can be understood as corresponding to and / or representing components with similar names described above with reference to Figures 1-12. As will be described in more detail below, any appropriate part of method 1300 can be executed using the controller of the CPM system (e.g., controller 180 of Figure 1).

[0137] As shown in Figure 13, method 1300 includes: at 1312, guiding a charged particle beam along the optical axis to a sample located in the sample plane; and at 1318, operating a foil lens corrector positioned along the optical axis to generate canceling spherical aberration. Specifically, operating the foil lens corrector at 1318 may include the following operation: making the canceling spherical aberration opposite in sign and at least substantially equal in magnitude to the spherical aberration components of the charged particle beam at the sample plane when the foil lens corrector is removed from the CPM system. As described herein, the canceling spherical aberration can be characterized by negative or positive spherical aberration coefficients.

[0138] As described herein, a foil lens corrector may include a foil through which a charged particle beam is at least partially transmitted. Operating the foil lens corrector at 1318 may involve guiding the charged particle beam to the foil such that the charged particle beam is incident on the foil at any of a variety of foil incident energies. As an example, the incident energy of the foil can be at least 5 keV, at least 7 keV, at least 10 keV, at least 15 keV, at least 20 keV, at least 30 keV, at least 50 keV, at least 70 keV, up to 80 keV, up to 60 keV, up to 40 keV, up to 25 keV, up to 17 keV, up to 12 keV, up to 8 keV, up to 6 keV, 5-8 keV, 7-12 keV, 5-15 keV, 5-20 keV, 5-30 keV, 5-40 keV, 5-60 keV, and / or 5-80 keV.

[0139] Furthermore, the foil lens corrector operating at 1318 may include transmitting a charged particle beam through the foil at any of a variety of transmittances, such as at least 5%, at least 10%, at least 20%, 30%, at least 50%, at least 70%, at least 80%, up to 95%, up to 75%, up to 60%, up to 40%, up to 25%, up to 15%, and / or up to 7%. As a more specific example, the foil lens corrector operating at 1318 may include guiding a charged particle beam to be incident on the foil with a foil incident energy of at least 5 keV and up to 80 keV, and transmitting the charged particle beam through the foil at a transmittance of at least 20%.

[0140] As described herein, a CPM system may include a booster tube configured to accelerate a charged particle beam within at least a portion of the CPM system. Therefore, as shown in Figure 13, method 1300 may include applying a booster tube voltage at 1316. Applying the booster tube voltage at 1316 may include applying a voltage such that the booster tube voltage is any of a variety of voltages, such as at least 5 kV, at least 7 kV, at least 10 kV, up to 12 kV, up to 8 kV, up to 6 kV, 5-8 kV, 7-12 kV, and / or 5-12 kV.

[0141] In various examples, operating the foil lens corrector at 1318 includes generating a corrector electrostatic potential at 1320 using the electrode assembly of the foil lens corrector. This corrector electrostatic potential is used to generate at least a portion of the canceling spherical aberration in the charged particle beam. Generating the corrector electrostatic potential at 1320 may include generating a corrector electrostatic potential that is at least substantially confined to a first side of the foil. In various examples, generating the corrector electrostatic potential at 1320 includes generating the corrector electrostatic potential only on the first side of the foil.

[0142] In various examples, generating the corrector electrostatic potential at 1320 includes: applying a first voltage to the first electrode of the electrode assembly at 1332; and / or applying a second voltage to the second electrode of the electrode assembly at 1334. While this disclosure generally relates to examples where the electrode assembly includes a first electrode and a second electrode, this is not a requirement for all examples, and within the scope of this disclosure, the electrode assembly may include a single electrode. Therefore, in some cases, the first electrode and / or the corresponding first voltage mentioned herein may be understood to refer to the only electrode of the electrode assembly.

[0143] As described herein, the first electrode voltage and the second electrode voltage can be understood as representing independent degrees of freedom that can be used to configure the operation of the foil lens corrector, for example, to produce the desired compensating spherical aberration. Therefore, in some examples, as shown in FIG13, method 1300 includes determining the first voltage and / or the second voltage at 1322, for example, to identify a combination of the first and second voltages that can produce the desired compensating spherical aberration. The first voltage and / or the second voltage can be determined at 1322 before applying the first voltage at 1332 and / or applying the second voltage at 1334.

[0144] As a more specific example, method 1300 and / or determining the voltage at 1322 may include: at 1324, applying a predetermined first voltage to the first electrode and determining a corresponding second voltage for generating the desired characteristics of the charged particle beam. In such an example, method 1300 may include: while the first electrode is maintained at the predetermined first voltage, changing the second voltage applied to the second electrode at 1326. Method 1300 may also include: at 1328, measuring characteristic beam properties of the charged particle beam corresponding to each second voltage as the second voltage changes; and at 1330, selecting a preferred second voltage corresponding to a preferred value of the characteristic beam property. The characteristic beam property may include and / or any of a variety of measurable characteristics of the charged particle beam, such as the characteristic beam diameter of the charged particle beam at the sample plane and / or the spherical aberration of the charged particle beam at the sample plane. In such an example, applying the first voltage at 1332 may include applying a predetermined first voltage to the first electrode and applying a preferred second voltage to the second electrode.

[0145] In other examples, the first voltage and / or the second voltage can be determined at 1322 in the opposite manner, for example by fixing the second voltage to a predetermined value and changing the first voltage to determine a preferred value for the first voltage.

[0146] In some examples, as shown in Figure 13, method 1300 further includes heating the foil of the foil lens corrector at 1310 with a corrector heater. As described herein, heating the foil with a corrector heater can help prevent contaminants from adhering to and / or removing such contaminants from the foil. In some examples, heating the foil at 1310 includes heating the foil to a temperature of approximately 200°C. In some examples, heating the foil at 1310 includes transferring thermal energy from the heating element of the corrector heater to the foil via a heater body that electrically isolates the heating element from the foil.

[0147] The foil can be heated at 1310 at any suitable point in time during operation of the CPM system and / or foil lens corrector. For example, heating the foil at 1310 may include heating the foil at least partially simultaneously with guiding the charged particle beam at 1312. Alternatively, the foil can be heated at 1310 before guiding the charged particle beam at 1312. For example, heating the foil at 1310 may include heating the foil to an elevated and / or predetermined initial temperature (e.g., approximately 200°C) before guiding the charged particle beam through it. This process can be used to protect the foil from damage that could otherwise occur due to the interaction between the charged particle beam and contaminants on the foil.

[0148] Guiding the charged particle beam at 1312 may involve guiding the charged particle beam to any suitable portion of the sample. For example, as shown in Figure 13, guiding the charged particle beam at 1312 may involve scanning the charged particle beam (and / or its focal position) relative to the sample at 1314 using one or more scanning deflectors of a CPM system. Scanning the charged particle beam relative to the sample in this manner can be used to probe surface regions of the sample, for example, to produce a photomicrograph of the sample. In various examples, scanning the charged particle beam at 1314 may involve scanning the charged particle beam in a region having a linear dimension (e.g., field of view) of at least 50 nm, at least 100 nm, at least 200 nm, at least 300 nm, at least 500 nm, at least 1000 nm, up to 1200 nm, up to 700 nm, up to 250 nm, up to 150 nm, and / or up to 75 nm.

[0149] The charged particle beam guided at 1312 may also include guiding the charged particle beam to have any of a variety of beam characteristics in the sample plane. As an example, guiding the charged particle beam at 1312 may include focusing the charged particle beam in the sample plane to a point with a characteristic diameter of at least 0.2 nm, at least 0.5 nm, at least 1 nm, at least 3 nm, at least 5 nm, up to 10 nm, up to 4 nm, up to 2 nm, up to 0.7 nm, up to 0.2 nm, 0.2–1 nm, 0.5–5 nm, and / or 1–10 nm. Alternatively, the charged particle beam guided at 1312 may include guiding the charged particle beam such that the charged particle beam has spherical aberration in the sample plane, characterized by third-order spherical aberration coefficients with a size of one or more of the following: up to 5 mm, up to 3 mm, up to 1 mm, up to 0.5 mm, and / or 0 mm.

[0150] Figure 14 and the following discussion are intended to provide a brief, general description of an exemplary computing environment in which the disclosed techniques can be implemented. For example, one or more aspects of the computing system of Figure 14 may represent and / or correspond to the controller 180 of Figure 1. Specifically, part or all of this computing environment may be used with the methods and apparatus described above, for example, to control a CPM system to guide a charged particle beam to a sample, to control a foil lens corrector to generate a suitable corrector electrostatic field to at least partially correct the spherical aberration of the charged particle beam, and / or to perform any part of the methods described above.

[0151] While not strictly necessary, the disclosed techniques are described within the general context of computer-executable instructions (e.g., program modules) executed by a personal computer (PC). Generally, program modules include routines, programs, objects, components, data structures, etc., that perform specific tasks or implement specific abstract data types. Furthermore, the disclosed techniques can be implemented using other computer system configurations, including handheld devices, tablets, multiprocessor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframes, virtual machines, containerized applications, etc. The disclosed techniques can also be practiced in distributed computing environments, where tasks are performed by remote processing devices connected via a communication network. In a distributed computing environment, program modules can reside in both local and remote memory storage devices. In some cases, such processing is provided within a CPM system. The disclosed system can be used to control image acquisition and provide a user interface, as well as to function as an image processor.

[0152] Referring to Figure 14, an exemplary system for implementing the disclosed technology includes a general-purpose computing device in the form of an exemplary PC 1400, comprising one or more processing units 1402, system memory 1404, and a system bus 1406 that couples various system components, including the system memory 1404, to the one or more processing units 1402. The system bus 1406 can be any of several types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus using various bus architectures. The exemplary system memory 1404 includes read-only memory (ROM) 1408 and random access memory (RAM) 1410. A basic input / output system (BIOS) 1412 is stored in the ROM 1408, containing basic routines that facilitate the transfer of information between components within the PC 1400. The PC 1400 may represent and / or correspond to the controller 180 of Figure 1.

[0153] The exemplary PC 1400 also includes one or more storage devices 1430, such as a hard disk drive for reading and writing to a hard disk, a disk drive for reading or writing to a removable disk, and an optical disc drive for reading or writing to a removable optical disc (e.g., a CD-ROM or other optical media). Such storage devices can be connected to the system bus 1406 via a hard disk drive interface, a disk drive interface, and an optical disc drive interface, respectively. The drives and their associated computer-readable media provide non-volatile storage of computer-readable instructions, data structures, program modules, and other data for the PC 1400. Other types of computer-readable media that can store PC-accessible data (e.g., magnetic tape, flash memory cards, solid-state drives, digital video disks, CDs, DVDs, RAM, ROMs, etc.) may also be used in the exemplary operating environment. Storage device 1430 may store multiple program modules, including an operating system, multiple operating systems, a virtual operating system, one or more applications, other program modules, and / or program data.

[0154] The exemplary PC 1400 may include various devices configured for a user interface. For example, a user may input commands and information to the PC 1400 via one or more input devices 1440, such as a keyboard and / or a pointing device such as a mouse. For example, a user may input commands to initiate image acquisition and / or initiate one or more methods disclosed herein. Other input devices may include digital cameras, microphones, joysticks, gamepads, buttons, dial pads, disc satellite antennas, scanners, etc. These and other input devices are generally connected to one or more processing units 1402 via a serial port interface coupled to the system bus 1406, but may also be connected via other interfaces, such as parallel ports, game ports, universal serial bus (USB), or wired or wireless network connections. A display 1446 or other type of display device is also connected to the system bus 1406 via an interface (such as a video adapter) and may display one or more images, such as samples, before, after, and / or during the execution of one or more methods disclosed herein. The display 1446 may also be used to select slices for processing or specific image alignment and alignment procedures, such as correlation, feature recognition, and preview area selection, or other image selection. It may also include other peripheral output devices, such as speakers and printers (not shown).

[0155] PC 1400 can operate in a networked environment using a logical connection to one or more remote computers (e.g., remote computer 1460). In some examples, one or more network or communication connections 1450 are included. Remote computer 1460 can be another PC, server, router, network PC and / or peer device, or other common network node, generally containing many or all of the elements described above relative to PC 1400, although only storage device 1462 is shown in Figure 14. PC 1400 and / or remote computer 1460 can be connected to a local area network (LAN) and / or wide area network (WAN). Such network environments are common in offices, enterprise-wide computer networks, intranets, and the Internet.

[0156] As shown in Figure 14, memory 1490 (or a portion of that memory or other memory) may store processor-executable instructions for adjusting the booster voltage, adjusting one or more voltages associated with the electrode assembly of the foil lens corrector, and / or for any other processes described herein. For example, when executed by a processor system, such processor-executable instructions may cause PC 1400 and / or another component (e.g., any CPM system and / or any suitable component of the foil lens corrector disclosed herein) to perform any of the methods disclosed herein. Furthermore, memory 1490 may contain processor-executable instructions for setting cross-correlation, image alignment (e.g., image rotation and translation), selecting reference images and regions of interest, and / or recording stage coordinates for alignment. In some examples, the processor-executable instructions may produce displayed images demonstrating slice recognition, processing of preview images, and / or acquisition of additional images.

[0157] General considerations

[0158] As used in this application and claims, the singular forms “a,” “an,” and “the” include the plural forms unless the context clearly indicates otherwise. Additionally, the term “comprising” means “including.” Furthermore, the term “coupled” does not exclude the existence of intermediate elements between coupled items.

[0159] Unless otherwise stated, the term "substantially" as used herein means the listed values ​​and / or properties and any values ​​and / or properties that are at least 75% of the listed values ​​and / or properties. Equivalently, the term "substantially" means the listed values ​​and / or properties and any values ​​and / or properties that differ from the listed values ​​and / or properties by a maximum of 25%. For example, "substantially equal" means quantities that are completely equal and quantities that differ from each other by a maximum of 25%.

[0160] The systems, apparatuses, and methods described herein should not be construed as limiting in any way. Rather, this disclosure is intended to relate to all novel and non-obvious features and aspects of the various disclosed examples individually, as well as in various combinations and sub-combinations. The disclosed systems, methods, and apparatuses are not limited to any particular aspect or feature or combination thereof, nor are they required to possess any one or more particular advantages or problems solved. Any operational theory should be readily apparent, but the disclosed systems, methods, and apparatuses are not limited to such operational theories.

[0161] Although some of the methods disclosed in this application are described in a specific order for ease of description, it should be understood that this descriptive method encompasses the rearrangement of the order of steps unless explicitly defined below. For example, operations described sequentially may be rearranged or performed simultaneously in some cases. Furthermore, for the sake of brevity, the accompanying drawings may not show the various ways in which the disclosed systems, methods, and apparatus may be used in combination with other systems, methods, and apparatuses. In addition, terms such as "produce" and "provide" are sometimes used in the specification to describe the disclosed methods. These terms are high-level abstractions of the actual operations performed. The actual operations corresponding to these terms will vary depending on the specific implementation and are readily apparent to those skilled in the art.

[0162] In some examples, values, procedures, etc., may be described using descriptive terms such as "lowest," "best," "minimum," "extreme," etc. It should be understood that such descriptions are intended to indicate that there are multiple available functional alternatives to choose from, and that such a choice is not necessarily better, smaller, or superior to other choices.

[0163] Innovations can be described within the general context of computer-executable instructions, such as those instructions included in a program module and executed on a computing system targeting a real or virtual processor. Generally, program modules or components include routines, programs, libraries, objects, classes, components, data structures, etc., that perform specific tasks or implement specific abstract data types. The functionality of a program module can be combined or split in different examples depending on specific needs. The computer-executable instructions used in a program module can execute within a local or distributed computing system. Generally, a computing system or computing device can be local or distributed and can contain any combination of dedicated hardware and / or general-purpose hardware with software that implements the functionality described herein, such as personal computers, handheld devices, tablets, multiprocessor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframes, virtual machines, containerized applications, etc.

[0164] In the various examples described herein, a module (such as a component or engine) can be "programmed" and / or "coded" to perform a specific operation or provide a specific function. This means that the computer-executable instructions of the module can be executed to perform such an operation, cause such an operation to be performed, or otherwise provide such functionality. While the functionality described with respect to a software component, module, or engine may be executed as a discrete software unit (e.g., a program, function, class method), it does not need to be implemented as a discrete unit. That is, the functionality can be incorporated into a larger or more general program, such as one or more lines of code within a larger or more general program.

[0165] The algorithms described may, for example, be embodied as software or firmware instructions executed by a digital computer. For instance, any of the disclosed methods may be executed by one or more computers or other computing hardware as part of a microscopic examination tool. The computer may be a computer system comprising one or more processors (processing devices) and tangible, non-transitory computer-readable media (e.g., one or more optical discs, volatile memory devices such as DRAM or SRAM), or non-volatile memory or storage devices such as hard disk drives, NVRAM, and solid-state drives (e.g., flash drives)). The one or more processors may execute computer-executable instructions stored on one or more tangible, non-transitory computer-readable media, thereby performing any of the techniques disclosed. For example, software for performing any of the disclosed examples may be stored as computer-executable instructions on one or more volatile, non-transitory computer-readable media, which, when executed by one or more processors, may cause one or more processors to perform any of the disclosed techniques or subsets of techniques.

[0166] Examples of the disclosed technology

[0167] Having described and illustrated the principles of the present disclosure with reference to the illustrated examples, it will be appreciated that modifications may be made to the arrangement and details of the illustrated examples without departing from these principles. For example, an example element implemented in software may be implemented in hardware, and vice versa. Similarly, techniques from any example may be combined with techniques described in any or more other examples. It should be understood that programs and functions such as those described with reference to the illustrated examples may be implemented in a single hardware or software module, or may be provided as separate modules. The specific arrangement described above is provided for ease of illustration, and other arrangements may also be used.

[0168] Example 1. A foil lens corrector for correcting spherical aberration in a charged particle beam generated by a charged particle microscope (CPM) system, the foil lens corrector comprising: a graphene foil configured to align with the optical axis of the CPM system; and an electrode assembly configured to generate a corrector electrostatic potential on a first side of the foil, wherein the foil is configured to support a space charge such that the optical axis intersects the space charge, and wherein the foil lens corrector is configured such that the corrector electrostatic potential generates a counteracting spherical aberration in the charged particle beam.

[0169] Example 2. A foil lens corrector for correcting spherical aberration in a charged particle beam generated by a charged particle microscope (CPM) system, the foil lens corrector comprising: a foil configured to align with the optical axis of the CPM system; and an electrode assembly configured to generate a corrector electrostatic potential, wherein the foil comprises graphene, and wherein the foil is configured to support a space charge such that the optical axis intersects with the space charge.

[0170] Example 3. A foil lens corrector as described in any of the examples herein, particularly Example 2, wherein the foil lens corrector is configured such that the corrector electrostatic potential produces a counteracting spherical aberration in the charged particle beam to at least partially correct the spherical aberration in the charged particle beam.

[0171] Example 4. A foil lens corrector as described in any of the examples herein, particularly Example 3, wherein the canceling spherical aberration is a negative spherical aberration.

[0172] Example 5. A foil lens corrector as described in any example herein, particularly Example 4, wherein the negative spherical aberration generated by the foil lens corrector is characterized by a third-order spherical aberration coefficient at a sample plane downstream of the foil lens corrector, the third-order spherical aberration coefficient being one or more of the following: at least -20 mm, at least -15 mm, at least -10 mm, at least -5 mm, at least -1 mm, at most 0 mm, at most -2 mm, at most -7 mm, at most -12 mm, or at most -17 mm.

[0173] Example 6. A foil lens corrector as described in any of the examples herein, particularly any of Examples 2 through 5, wherein the canceling spherical aberration is a positive spherical aberration.

[0174] Example 7. A foil lens corrector as described in any example herein, particularly Example 6, wherein the positive spherical aberration generated by the foil lens corrector is characterized by a third-order spherical aberration coefficient at a sample plane downstream of the foil lens corrector, the third-order spherical aberration coefficient being one or more of the following: at least 0 mm, at least 2 mm, at least 7 mm, at least 12 mm, at least 17 mm, at most 20 mm, at most 15 mm, at most 10 mm, at most 5 mm, or at most 1 mm.

[0175] Example 8. A foil lens corrector as described in any of the examples herein, particularly any of Examples 2 through 5, wherein the foil lens corrector is configured to act as a converging lens for the charged particle beam.

[0176] Example 9. A foil lens corrector as described in any of the examples herein, particularly any of Examples 2 through 8, wherein the foil lens corrector is configured to act as a diverging lens for the charged particle beam.

[0177] Example 10. A foil lens corrector as described in any of the examples herein, particularly any of Examples 2 through 9, wherein the foil comprises one of: (i) monolayer graphene; (ii) bilayer graphene; (iii) trilayer graphene; or (iv) more than three layers of graphene.

[0178] Example 11. A foil lens corrector as described in any example herein, particularly any of Examples 2 through 10, wherein the foil lens corrector is configured such that during operation of the CPM system, when the charged particle beam is incident on the foil with a certain foil incident energy, the charged particle beam passes through the foil with one or more of the following transmittances: at least 5%, at least 10%, at least 20%, at least 30%, at least 50%, at least 70%, at least 80%, up to 95%, up to 75%, up to 60%, up to 40%, up to 25%, up to 15%, or up to 7%.

[0179] Example 12. A foil lens corrector as described in any example herein, particularly Example 11, wherein the incident energy of the foil is one or more of the following: at least 5 kiloelectron volts (keV), at least 7 keV, at least 10 keV, at least 15 keV, at least 20 keV, at least 30 keV, at least 50 keV, at least 70 keV, up to 80 keV, up to 60 keV, up to 40 keV, up to 25 keV, up to 17 keV, up to 12 keV, up to 8 keV, up to 6 keV, 5-8 keV, 7-12 keV, 5-15 keV, 5-20 keV, 5-30 keV, 5-40 keV, 5-60 keV, or 5-80 keV.

[0180] Example 13. A foil lens corrector as described in any of the examples herein, particularly any of Examples 2 to 12, wherein the electrode assembly is configured to generate the corrector electrostatic potential on a first side of the foil, and wherein the foil is configured to shield the corrector electrostatic potential such that the maximum amplitude of the corrector electrostatic potential generated by the electrode assembly on a second side of the foil opposite to the first side of the foil is at most 1% of the maximum amplitude of the corrector electrostatic potential on the first side of the foil.

[0181] Example 14. A foil lens corrector as described in any of the examples herein, particularly any of Examples 2 to 13, wherein the electrode assembly includes an electrode configured to generate at least a portion of the corrector electrostatic potential on a first side of the foil, and wherein the foil is configured to at least partially shield the corrector electrostatic potential from extending to a second side of the foil opposite to the first side of the foil.

[0182] Example 15. A foil lens corrector as described in any of the examples herein, particularly any of Examples 2 to 14, wherein the electrode assembly comprises a first electrode and a second electrode, and wherein the foil lens corrector is configured to generate at least a portion of the corrector electrostatic potential by applying a first electrode voltage to the first electrode and a second electrode voltage to the second electrode, while the foil is maintained at a foil potential different from one or both of the first electrode voltage and the second electrode voltage.

[0183] Example 16. A foil lens corrector as described in any example herein, particularly Example 15, wherein each of the first electrode and the second electrode is located on a common side of the foil.

[0184] Example 17. A foil lens corrector as described in any of the examples herein, particularly any of Examples 2 through 16, wherein the electrode assembly is configured to generate the corrector electrostatic potential at an upstream location on the foil.

[0185] Example 18. A foil lens corrector as described in any of the examples herein, particularly any of Examples 2 through 17, wherein the electrode assembly is configured to generate the corrector electrostatic potential at a location downstream of the foil.

[0186] Example 19. A foil lens corrector as described in any of the examples herein, particularly any of Examples 2 through 18, wherein the CPM system includes a booster tube configured to accelerate the charged particle beam within at least a portion of the CPM system, and wherein at least a portion of the foil lens corrector is electrically coupled to the booster tube.

[0187] Example 20. A foil lens corrector as described in any example herein, particularly Example 19, wherein the foil is electrically coupled to the booster tube.

[0188] Example 21. The foil lens corrector as described in any of the examples herein, particularly any of Examples 19 to 20, further includes a corrector housing that electrically couples the booster tube to the foil.

[0189] Example 22. A foil lens corrector as described in any of the examples herein, particularly any of Examples 19 to 21, wherein the foil lens corrector is configured within a booster tube.

[0190] Example 23. A foil lens corrector as described in any of the examples herein, particularly any of Examples 19 to 22, wherein the booster tube is configured to accelerate the charged particle beam to an enhanced potential along the optical axis within the booster tube, and wherein the foil lens corrector is configured such that the total electrostatic potential amplitude along the optical axis within the foil lens corrector is less than the enhanced potential.

[0191] Example 24. The foil lens corrector as described in any example herein, particularly Example 23, wherein the enhancement potential can be one or more of the following: at least 4 keV, at least 6 keV, at least 8 keV, at least 10 keV, at least 12 keV, up to 14 keV, up to 11 keV, up to 9 keV, up to 7 keV, up to 5 keV, 4-9 keV, 6-11 keV, 8-14 keV, or 4-14 keV.

[0192] Example 25. The foil lens corrector as described in any of the examples herein, particularly any of Examples 2 through 24, further includes a shielding electrode defining a foil aperture, wherein the foil spans the foil aperture.

[0193] Example 26. A foil lens corrector as described in any of the examples herein, particularly Example 25, wherein the foil completely covers the foil aperture.

[0194] Example 27. A foil lens corrector as described in any of the examples herein, particularly any of Examples 25 to 26, wherein the foil aperture is a circular aperture.

[0195] Example 28. A foil lens corrector as described in any of the examples herein, particularly any of Examples 25 to 27, wherein the foil aperture diameter is one or more of the following: at least 50 micrometers (µm), at least 100 µm, at least 200 µm, at least 300 µm, at least 500 µm, up to 700 µm, up to 400 µm, up to 250 µm, up to 150 µm, or up to 75 µm.

[0196] Example 29. A foil lens corrector as described in any of the examples herein, particularly any of Examples 25 to 28, wherein the foil independently spans the foil aperture.

[0197] Example 30. A foil lens corrector as described in any of the examples herein, particularly any of Examples 25 to 28, wherein the foil is supported by a foil support structure that at least partially spans the foil aperture.

[0198] Example 31. As shown in any of the examples herein, specifically Example 30, the foil lens corrector, wherein the foil support structure comprises one or more of a carrier mesh, a grid, or a perforated structure.

[0199] Example 32. The foil lens corrector as described in any of the examples herein, particularly any of Examples 2 to 31, further comprises one or both of the following: (i) a first shielding electrode supporting the foil; and (ii) a second shielding electrode positioning the electrode assembly between the first and second shielding electrodes.

[0200] Example 33. A foil lens corrector as described in any example herein, particularly Example 32, wherein the second shielding electrode is electrically coupled to the first shielding electrode.

[0201] Example 34. A foil lens corrector as described in any of the examples herein, particularly Examples 32 to 33, wherein the first shielding electrode includes a foil aperture at least partially covered by the foil, and wherein the second shielding electrode includes a second aperture axially aligned with the foil aperture.

[0202] Example 35. The foil lens corrector as described in any of the examples herein, particularly any of Examples 2 through 34, further includes a corrector housing supporting at least one or both of the foil and the electrode assembly.

[0203] Example 36. A foil lens corrector as described in any example herein, particularly Example 35, wherein the electrode assembly comprises one or more electrodes configured to generate at least a portion of the corrector's electrostatic potential, and wherein one or more of the electrodes are electrically insulated from the corrector housing.

[0204] Example 37. The foil lens corrector as described in any of the examples herein, particularly any of Examples 35 to 36, further includes an insulating support that supports one or more of the electrodes relative to the corrector housing and electrically insulates the one or more of the electrodes from the corrector housing.

[0205] Example 38. A foil lens corrector as described in any of the examples herein, particularly any of Examples 35 to 37, wherein the electrode assembly comprises one or more electrodes configured to generate at least a portion of the corrector's electrostatic potential, and wherein the corrector housing at least partially supports one or more of the electrodes within the corrector housing.

[0206] Example 39. A foil lens corrector as described in any of the examples herein, particularly any of Examples 35 to 38, wherein the corrector housing includes a foil aperture, and wherein the foil is coupled to the corrector housing and covers the foil aperture.

[0207] Example 40. A foil lens corrector as described in any of the examples herein, particularly Example 39, wherein the foil completely covers the foil aperture.

[0208] Example 41. A foil lens corrector as described in any of the examples herein, particularly any of Examples 39 to 40, wherein the foil aperture is a circular aperture.

[0209] Example 42. A foil lens corrector as described in any of the examples herein, particularly any of Examples 39 to 41, wherein the foil aperture diameter is one or more of the following: at least 50 µm, at least 100 µm, at least 200 µm, at least 300 µm, at least 500 µm, at most 700 µm, at most 400 µm, at most 250 µm, at most 150 µm, or at most 75 µm.

[0210] Example 43. A foil lens corrector as described in any of the examples herein, particularly any of Examples 35 to 42, wherein the corrector housing comprises one or both of the following: (i) a first shielding electrode supporting the foil; and (ii) a second shielding electrode that positions the electrode assembly between the first and second shielding electrodes.

[0211] Example 44. A foil lens corrector as described in any example herein, particularly Example 43, wherein one or both of the first shielding electrode and the second shielding electrode are configured to form the corrector electrostatic potential within the corrector housing and to at least partially confine the corrector electrostatic potential within the corrector housing.

[0212] Example 45. A foil lens corrector as described in any of the examples herein, particularly any of Examples 43 to 44, wherein the second shielding electrode is electrically coupled to the first shielding electrode.

[0213] Example 46. A foil lens corrector as described in any of the examples herein, particularly any of Examples 43 to 45, wherein the corrector housing comprises a housing that is in direct contact with each of the first shielding electrode and the second shielding electrode.

[0214] Example 47. A foil lens corrector as described in any of the examples herein, particularly any of Examples 43 to 46, wherein the first shielding electrode comprises a foil aperture.

[0215] Example 48. A foil lens corrector as described in any of the examples herein, particularly Example 47, wherein the second shielding electrode includes a second aperture axially aligned with the foil aperture.

[0216] Example 49. The foil lens corrector as described in any of the examples herein, particularly any of Examples 2 through 48, further includes a corrector heater configured to heat the foil.

[0217] Example 50. A foil lens corrector as described in any example herein, particularly Example 49, wherein the corrector heater is configured to heat the foil to a temperature of approximately 200°C.

[0218] Example 51. A foil lens corrector as described in any of the examples herein, particularly any of Examples 49 to 50, wherein the corrector heater is configured to heat the foil during operation of the foil lens corrector.

[0219] Example 52. A foil lens corrector as described in any of the examples herein, particularly any of Examples 49 to 51, wherein the corrector heater is configured to heat the foil during operation of the CPM system.

[0220] Example 53. A foil lens corrector as described in any of the examples herein, particularly any of Examples 49 to 52, wherein the corrector heater includes a heating element configured to receive current and a heater body, and wherein the heating element is thermally coupled to the foil through the heater body.

[0221] Example 54. A foil lens corrector as described in any of the examples herein, particularly Example 53, wherein the heater body comprises an electrically insulating portion and a conductive portion.

[0222] Example 55. A foil lens corrector as described in any of the examples herein, particularly any of Examples 53 to 54, wherein the electrically insulating portion is in direct contact with each of the heating element and the conductive portion.

[0223] Example 56. A foil lens corrector as described in any of the examples herein, particularly any of Examples 53 to 55, wherein the electrically insulating portion comprises aluminum nitride.

[0224] Example 57. A foil lens corrector as described in any of the examples herein, particularly any of Examples 53 to 56, wherein the conductive portion is in direct contact with the foil.

[0225] Example 58. The foil lens corrector as described in any of the examples herein, particularly any of Examples 53 to 57, further includes a corrector housing that supports at least one or both of the foil and / or the electrode assembly, and wherein the conductive portion is in direct contact with the corrector housing.

[0226] Example 59. A foil lens corrector as described in any of the examples herein, particularly any of Examples 53 to 58, wherein the conductive portion comprises molybdenum.

[0227] Example 60. A foil lens corrector as described in any of the examples herein, particularly any of Examples 53 to 59, wherein the conductive portion defines at least a portion of a heater conduit configured to allow the charged particle beam to pass through the heater body.

[0228] Example 61. A foil lens corrector as described in any of the examples herein, particularly any of Examples 53 to 60, wherein the heating element is electrically isolated from the foil.

[0229] Example 62. A foil lens corrector as described in any of the examples herein, particularly any of Examples 53 to 61, further includes a corrector housing that supports at least one or both of the foil and / or the electrode assembly, and wherein the heater body electrically isolates the heating element from one or both of the foil and the corrector housing.

[0230] Example 63. A foil lens corrector as described in any of the examples herein, particularly any of Examples 53 to 62, wherein the heater body comprises aluminum nitride.

[0231] Example 64. The foil lens corrector as described in any of the examples herein, particularly any of Examples 53 to 63, further includes a corrector housing that supports at least one or both of the foil and / or the electrode assembly, and wherein the heater body is in direct contact with one or both of the foil and the corrector housing.

[0232] Example 65. The foil lens corrector as described in any of the examples herein, particularly any of Examples 53 to 64, further includes a corrector housing that supports at least one or both of the foil and / or the electrode assembly, and wherein the heating element is spaced apart from one or both of the foil and the corrector housing.

[0233] Example 66. A foil lens corrector as described in any of the examples herein, particularly any of Examples 53 to 65, wherein one or both of the heating element and the heater body define at least a portion of a heater conduit configured to allow the charged particle beam to pass through one or both of the corrector heater and the heater body.

[0234] Example 67. A foil lens corrector as described in any of the examples herein, particularly any of Examples 49 to 66, further includes a corrector housing that supports at least one or both of the foil and / or the electrode assembly, wherein the corrector housing defines a housing recess extending toward the electrode assembly, and wherein at least a portion of the corrector heater is received within the housing recess.

[0235] Example 68. A foil lens corrector as described in any of the examples herein, particularly any of Examples 2 through 67, wherein the CPM system comprises a scanning electron microscope (SEM).

[0236] Example 69. A foil lens corrector as described in any of the examples herein, particularly any of Examples 2 through 68, wherein the CPM system comprises a transmission electron microscope (TEM).

[0237] Example 70. A foil lens corrector as described in any of the examples herein, particularly any of Examples 2 through 69, wherein the CPM system includes one or more scanning deflectors configured to scan the charged particle beam relative to a sample, and wherein the foil lens corrector is located upstream of one or more of the scanning deflectors.

[0238] Example 71. A foil lens corrector as described in any of the examples herein, particularly any of Examples 2 through 70, wherein the CPM system includes an objective lens assembly, and wherein the foil lens corrector is located upstream of at least a portion of the objective lens assembly.

[0239] Example 72. A foil lens corrector as described in any of the examples herein, particularly any of Examples 2 through 71, wherein the CPM system includes a condenser lens assembly, and wherein the foil lens corrector is located downstream of at least a portion of the condenser lens assembly.

[0240] Example 73. A foil lens corrector for correcting spherical aberration in a charged particle beam generated by a charged particle microscope (CPM) system, the foil lens corrector comprising: a foil configured to align with the optical axis of the CPM system; and an electrode assembly configured to generate a corrector electrostatic potential on a first side of the foil, wherein the foil is configured to support a space charge such that the optical axis intersects the space charge, wherein the foil lens corrector is configured such that, during operation of the CPM system, the corrector electrostatic potential generates counteracting spherical aberration in the charged particle beam to at least partially correct the spherical aberration in the charged particle beam when the charged particle beam is incident on the foil with a foil incident energy of at least 5 keV and at most 80 keV and the charged particle beam is transmitted through the foil with a transmittance of at least 20%.

[0241] Example 74. A foil lens corrector for correcting spherical aberration in a charged particle beam generated by a charged particle microscope (CPM) system, the foil lens corrector comprising: a corrector housing; a foil supported by the corrector housing; and an electrode assembly supported by the corrector housing and configured to generate a corrector electrostatic potential, wherein the corrector housing is configured to support the foil aligned with the optical axis of the CPM system, wherein the foil is configured to support a space charge such that the optical axis intersects the space charge, and wherein the foil lens corrector is configured such that during operation of the CPM system, the charged particle beam is incident on the foil with a foil incident energy of at least 5 keV and at most 80 keV, and the charged particle beam is transmitted through the foil with a transmittance of at least 20%.

[0242] Example 75. A foil lens corrector as described in any of the examples herein, particularly Example 74, wherein the foil lens corrector is configured to produce negative spherical aberration in the charged particle beam.

[0243] Example 76. A foil lens corrector as described in any example herein, particularly Example 75, wherein the negative spherical aberration generated by the foil lens corrector is characterized by a third-order spherical aberration coefficient at a sample plane downstream of the foil lens corrector, the third-order spherical aberration coefficient being one or more of the following: at least -20 mm, at least -15 mm, at least -10 mm, at least -5 mm, at most -2 mm, at most -7 mm, at most -12 mm, or at most -17 mm.

[0244] Example 77. A foil lens corrector as described in any of the examples herein, particularly any of Examples 74 to 76, wherein the foil lens corrector is configured to produce positive spherical aberration in the charged particle beam.

[0245] Example 78. A foil lens corrector as described in any example herein, particularly Example 77, wherein the positive spherical aberration generated by the foil lens corrector is characterized by a third-order spherical aberration coefficient at a sample plane downstream of the foil lens corrector, the third-order spherical aberration coefficient being one or more of the following: at least 0 mm, at least 2 mm, at least 7 mm, at least 12 mm, at least 17 mm, at most 20 mm, at most 15 mm, at most 10 mm, at most 5 mm, or at most 1 mm.

[0246] Example 79. A foil lens corrector as described in any of the examples herein, particularly any of Examples 74 to 78, wherein the foil lens corrector is configured to act as a converging lens for the charged particle beam.

[0247] Example 80. A foil lens corrector as described in any of the examples herein, particularly any of Examples 74 to 79, wherein the foil lens corrector is configured to act as a diverging lens for the charged particle beam.

[0248] Example 81. A foil lens corrector as described in any of the examples herein, particularly any of Examples 74 to 80, wherein the foil comprises graphene.

[0249] Example 82. A foil lens corrector as described in any of the examples herein, particularly any of Examples 74 to 81, wherein the foil comprises one of: (i) monolayer graphene; (ii) bilayer graphene; (iii) trilayer graphene; or (iv) more than three layers of graphene.

[0250] Example 83. A foil lens corrector as described in any of the examples herein, particularly any of Examples 74 to 82, wherein the electrode assembly is configured to generate the corrector electrostatic potential on a first side of the foil, and wherein the foil is configured to shield the corrector electrostatic potential such that the maximum amplitude of the corrector electrostatic potential generated by the electrode assembly on a second side of the foil opposite to the first side of the foil is at most 1% of the maximum amplitude of the corrector electrostatic potential on the first side of the foil.

[0251] Example 84. A foil lens corrector as described in any of the examples herein, particularly any of Examples 74 to 83, wherein the electrode assembly includes an electrode configured to generate at least a portion of the corrector electrostatic potential on a first side of the foil, and wherein the foil is configured to at least partially shield the corrector electrostatic potential from extending to a second side of the foil opposite to the first side of the foil.

[0252] Example 85. A foil lens corrector as described in any of the examples herein, particularly any of Examples 74 to 84, wherein the electrode assembly comprises a first electrode and a second electrode, and wherein the foil lens corrector is configured to generate at least a portion of the corrector electrostatic potential by applying a first electrode voltage to the first electrode and a second electrode voltage to the second electrode, while the foil is maintained at a foil potential different from one or both of the first electrode voltage and the second electrode voltage.

[0253] Example 86. A foil lens corrector as described in any example herein, particularly Example 85, wherein each of the first electrode and the second electrode is located on a common side of the foil.

[0254] Example 87. A foil lens corrector as described in any of the examples herein, particularly any of Examples 74 to 86, wherein the electrode assembly is configured to generate the corrector electrostatic potential at an upstream location on the foil.

[0255] Example 88. A foil lens corrector as described in any of the examples herein, particularly any of Examples 74 to 87, wherein the electrode assembly is configured to generate the corrector electrostatic potential at a location downstream of the foil.

[0256] Example 89. A foil lens corrector as described in any of the examples herein, particularly any of Examples 74 to 88, wherein the CPM system includes a booster tube configured to accelerate the charged particle beam within at least a portion of the CPM system, and wherein at least a portion of the foil lens corrector is electrically coupled to the booster tube.

[0257] Example 90. A foil lens corrector as described in any example herein, particularly Example 89, wherein the foil is electrically coupled to the booster tube.

[0258] Example 91. The foil lens corrector as described in any of the examples herein, particularly any of Examples 89 to 90, further includes a corrector housing that electrically couples the booster tube to the foil.

[0259] Example 92. A foil lens corrector as described in any of the examples herein, particularly any of Examples 89 to 91, wherein the foil lens corrector is configured to be at least partially within the booster tube.

[0260] Example 93. A foil lens corrector as described in any of the examples herein, particularly any of Examples 89 to 92, wherein the booster tube is configured to accelerate the charged particle beam to an enhanced potential along the optical axis within the booster tube, and wherein the foil lens corrector is configured such that the total electrostatic potential amplitude along the optical axis within the foil lens corrector is less than the amplitude of the enhanced potential.

[0261] Example 94. The foil lens corrector as described in any example herein, particularly Example 93, wherein the enhancement potential can be one or more of the following: at least 4 keV, at least 6 keV, at least 8 keV, at least 10 keV, at least 12 keV, up to 14 keV, up to 11 keV, up to 9 keV, up to 7 keV, up to 5 keV, 4-9 keV, 6-11 keV, 8-14 keV, or 4-14 keV.

[0262] Example 95. The foil lens corrector as described in any of the examples herein, particularly any of Examples 74 to 94, further includes a shielding electrode defining a foil aperture, wherein the foil spans the foil aperture.

[0263] Example 96. A foil lens corrector as described in any example herein, particularly Example 95, wherein the foil completely covers the foil aperture.

[0264] Example 97. A foil lens corrector as described in any of the examples herein, particularly any of Examples 95 to 96, wherein the foil aperture is a circular aperture.

[0265] Example 98. A foil lens corrector as described in any of the examples herein, particularly any of Examples 95 to 97, wherein the foil aperture diameter is one or more of the following: at least 50 µm, at least 100 µm, at least 200 µm, at least 300 µm, at least 500 µm, at most 700 µm, at most 400 µm, at most 250 µm, at most 150 µm, or at most 75 µm.

[0266] Example 99. A foil lens corrector as described in any of the examples herein, particularly any of Examples 95 to 98, wherein the foil independently spans the foil aperture.

[0267] Example 100. A foil lens corrector as described in any of the examples herein, particularly any of Examples 95 to 99, wherein the foil is supported by a foil support structure that at least partially spans the foil aperture.

[0268] Example 101. A foil lens corrector as described in any example herein, particularly Example 100, wherein the foil support structure comprises one or more of a carrier mesh, a grid, or a perforated structure.

[0269] Example 102. The foil lens corrector as described in any of the examples herein, particularly any of Examples 74 to 101, further comprises one or both of the following: (i) a first shielding electrode supporting the foil; and (ii) a second shielding electrode positioning the electrode assembly between the first and second shielding electrodes.

[0270] Example 103. A foil lens corrector as described in any example herein, particularly Example 102, wherein the second shielding electrode is electrically coupled to the first shielding electrode.

[0271] Example 104. A foil lens corrector as described in any of the examples herein, particularly Examples 101 to 103, wherein the first shielding electrode includes a foil aperture at least partially covered by the foil, and wherein the second shielding electrode includes a second aperture axially aligned with the foil aperture.

[0272] Example 105. The foil lens corrector as described in any of the examples herein, particularly any of Examples 74 to 104, further includes a corrector housing supporting at least one or both of the foil and the electrode assembly.

[0273] Example 106. A foil lens corrector as described in any example herein, particularly Example 105, wherein the electrode assembly comprises one or more electrodes configured to generate at least a portion of the corrector's electrostatic potential, and wherein one or more of the electrodes are electrically insulated from the corrector housing.

[0274] Example 107. The foil lens corrector as described in any of the examples herein, particularly any of Examples 105 to 106, further includes an insulating support that supports one or more of the electrodes relative to the corrector housing and electrically insulates the one or more of the electrodes from the corrector housing.

[0275] Example 108. A foil lens corrector as described in any of the examples herein, particularly any of Examples 105 to 107, wherein the electrode assembly comprises one or more electrodes configured to generate at least a portion of the corrector's electrostatic potential, and wherein the corrector housing at least partially supports one or more of the electrodes within the corrector housing.

[0276] Example 109. A foil lens corrector as described in any of the examples herein, particularly any of Examples 105 to 108, wherein the corrector housing includes a foil aperture, and wherein the foil is coupled to the corrector housing and covers the foil aperture.

[0277] Example 110. A foil lens corrector as described in any example herein, particularly Example 109, wherein the foil completely covers the foil aperture.

[0278] Example 111. A foil lens corrector as described in any of the examples herein, particularly any of Examples 109 to 110, wherein the foil aperture is a circular aperture.

[0279] Example 112. A foil lens corrector as described in any of the examples herein, particularly any of Examples 109 to 111, wherein the foil aperture diameter is one or more of the following: at least 50 µm, at least 100 µm, at least 200 µm, at least 300 µm, at least 500 µm, at most 700 µm, at most 400 µm, at most 250 µm, at most 150 µm, or at most 75 µm.

[0280] Example 113. A foil lens corrector as described in any of the examples herein, particularly any of Examples 105 to 112, wherein the corrector housing comprises one or both of the following: (i) a first shielding electrode supporting the foil; and (ii) a second shielding electrode that positions the electrode assembly between the first and second shielding electrodes.

[0281] Example 114. A foil lens corrector as described in any example herein, particularly Example 113, wherein one or both of the first shielding electrode and the second shielding electrode are configured to form the corrector electrostatic potential within the corrector housing and to at least partially confine the corrector electrostatic potential within the corrector housing.

[0282] Example 115. A foil lens corrector as described in any of the examples herein, particularly any of Examples 113 to 114, wherein the second shielding electrode is electrically coupled to the first shielding electrode.

[0283] Example 116. A foil lens corrector as described in any of the examples herein, particularly any of Examples 113 to 115, wherein the corrector housing comprises a housing that is in direct contact with each of the first shielding electrode and the second shielding electrode.

[0284] Example 117. A foil lens corrector as described in any of the examples herein, particularly any of Examples 113 to 116, wherein the first shielding electrode comprises a foil aperture.

[0285] Example 118. A foil lens corrector as described in any example herein, particularly Example 117, wherein the second shielding electrode includes a second aperture axially aligned with the foil aperture.

[0286] Example 119. The foil lens corrector as described in any of the examples herein, particularly any of Examples 64 to 118, further includes a corrector heater configured to heat the foil.

[0287] Example 120. A foil lens corrector as described in any example herein, particularly Example 119, wherein the corrector heater is configured to heat the foil to a temperature of approximately 200°C.

[0288] Example 121. A foil lens corrector as described in any of the examples herein, particularly any of Examples 119 to 120, wherein the corrector heater is configured to heat the foil during operation of the foil lens corrector.

[0289] Example 122. A foil lens corrector as described in any of the examples herein, particularly any of Examples 119 to 121, wherein the corrector heater is configured to heat the foil during operation of the CPM system.

[0290] Example 123. A foil lens corrector as described in any of the examples herein, particularly any of Examples 119 to 122, wherein the corrector heater includes a heating element configured to receive current and a heater body, and wherein the heating element is thermally coupled to the foil through the heater body.

[0291] Example 124. A foil lens corrector as described in any example herein, particularly Example 123, wherein the heater body comprises an electrically insulating portion and a conductive portion.

[0292] Example 125. A foil lens corrector as described in any of the examples herein, particularly any of Examples 123 to 124, wherein the electrically insulating portion is in direct contact with each of the heating element and the conductive portion.

[0293] Example 126. A foil lens corrector as described in any of the examples herein, particularly any of Examples 123 to 125, wherein the electrically insulating portion comprises aluminum nitride.

[0294] Example 127. A foil lens corrector as described in any of the examples herein, particularly any of Examples 123 to 126, wherein the conductive portion is in direct contact with the foil.

[0295] Example 128. The foil lens corrector as described in any of the examples herein, particularly any of Examples 123 to 127, further includes a corrector housing that supports at least one or both of the foil and / or the electrode assembly, and wherein the conductive portion is in direct contact with the corrector housing.

[0296] Example 129. A foil lens corrector as described in any of the examples herein, particularly any of Examples 123 to 128, wherein the conductive portion comprises molybdenum.

[0297] Example 130. A foil lens corrector as described in any of the examples herein, particularly any of Examples 123 to 129, wherein the conductive portion defines at least a portion of a heater conduit configured to allow the charged particle beam to pass through the heater body.

[0298] Example 131. A foil lens corrector as described in any of the examples herein, particularly any of Examples 123 to 130, wherein the heater body electrically isolates the heating element from one or both of the foil and the corrector housing.

[0299] Example 132. A foil lens corrector as described in any of the examples herein, particularly any of Examples 123 to 131, wherein the heater body comprises aluminum nitride.

[0300] Example 133. A foil lens corrector as described in any of the examples herein, particularly any of Examples 123 to 132, wherein the heater body is in direct contact with one or both of the foil and the corrector housing.

[0301] Example 134. A foil lens corrector as described in any of the examples herein, particularly any of Examples 123 to 133, wherein the heating element is spaced apart from one or both of the foil and the corrector housing.

[0302] Example 135. A foil lens corrector as described in any of the examples herein, particularly any of Examples 123 to 134, wherein one or both of the heating element and the heater body define at least a portion of a heater conduit configured to allow the charged particle beam to pass through the corrector heater.

[0303] Example 136. The foil lens corrector as described in any of the examples herein, particularly any of Examples 123 to 135, further includes a corrector housing that supports at least one or both of the foil and / or the electrode assembly, wherein the corrector housing defines a housing recess extending toward the electrode assembly, and wherein at least a portion of the corrector heater is received within the housing recess.

[0304] Example 137. A foil lens corrector as described in any of the examples herein, particularly any of Examples 74 to 136, wherein the CPM system comprises a scanning electron microscope (SEM).

[0305] Example 138. A foil lens corrector as described in any of the examples herein, particularly any of Examples 74 to 137, wherein the CPM system comprises a transmission electron microscope (TEM).

[0306] Example 139. A foil lens corrector as described in any of the examples herein, particularly any of Examples 74 to 138, wherein the CPM system includes one or more scanning deflectors configured to scan the charged particle beam relative to a sample, and wherein the foil lens corrector is located upstream of one or more of the scanning deflectors.

[0307] Example 140. A foil lens corrector as described in any of the examples herein, particularly any of Examples 74 to 139, wherein the CPM system includes an objective lens assembly, and wherein the foil lens corrector is located upstream of at least a portion of the objective lens assembly.

[0308] Example 141. A foil lens corrector as described in any of the examples herein, particularly any of Examples 74 to 140, wherein the CPM system includes a condenser lens assembly, and wherein the foil lens corrector is located downstream of at least a portion of the condenser lens assembly.

[0309] Example 142. A foil lens corrector for correcting spherical aberration in a charged particle beam generated by a charged particle microscope (CPM) system, the foil lens corrector comprising: a foil configured to align with the optical axis of the CPM system; and an electrode assembly configured to generate a corrector electrostatic potential only on a first side of the foil, wherein the foil is configured to support a space charge such that the optical axis intersects the space charge, wherein the foil lens corrector is configured to function as a converging lens to generate counteracting spherical aberration in the charged particle beam, thereby at least partially correcting the spherical aberration of the charged particle beam.

[0310] Example 143. A foil lens corrector for correcting spherical aberration in a charged particle beam generated by a charged particle microscope (CPM) system, the foil lens corrector comprising: a corrector housing; a foil supported by the corrector housing; and an electrode assembly supported by the corrector housing and configured to generate a corrector electrostatic potential only on a first side of the foil, wherein the corrector housing is configured to support the foil aligned with the optical axis of the CPM system, wherein the foil is configured to support a space charge such that the optical axis intersects the space charge, and wherein the foil is configured to act as a converging lens for the charged particle beam.

[0311] Example 144. A foil lens corrector as described in any example herein, particularly Example 143, wherein the foil lens corrector is configured to produce negative spherical aberration in the charged particle beam.

[0312] Example 145. A foil lens corrector as described in any example herein, particularly Example 144, wherein the negative spherical aberration generated by the foil lens corrector is characterized by a third-order spherical aberration coefficient at a sample plane downstream of the foil lens corrector, the third-order spherical aberration coefficient being one or more of the following: at least -20 mm, at least -15 mm, at least -10 mm, at least -5 mm, at most -2 mm, at most -7 mm, at most -12 mm, or at most -17 mm.

[0313] Example 146. A foil lens corrector as described in any of the examples herein, particularly Example 143, wherein the foil lens corrector is configured to produce positive spherical aberration in the charged particle beam.

[0314] Example 147. A foil lens corrector as described in any example herein, particularly Example 146, wherein the positive spherical aberration generated by the foil lens corrector is characterized by a third-order spherical aberration coefficient at a sample plane downstream of the foil lens corrector, the third-order spherical aberration coefficient being one or more of the following: at least 0 mm, at least 2 mm, at least 7 mm, at least 12 mm, at least 17 mm, at most 20 mm, at most 15 mm, at most 10 mm, at most 5 mm, or at most 1 mm.

[0315] Example 148. A foil lens corrector as described in any of the examples herein, particularly any of Examples 143 to 147, wherein the foil lens corrector is configured to act as a diverging lens for the charged particle beam.

[0316] Example 149. A foil lens corrector as described in any of the examples herein, particularly any of Examples 143 to 148, wherein the foil comprises graphene.

[0317] Example 150. A foil lens corrector as described in any of the examples herein, particularly any of Examples 143 to 149, wherein the foil comprises one of: (i) monolayer graphene; (ii) bilayer graphene; (iii) trilayer graphene; or (iv) more than three layers of graphene.

[0318] Example 151. A foil lens corrector as described in any of the examples herein, particularly any of Examples 143 to 150, wherein the foil lens corrector is configured such that during operation of the CPM system, when the charged particle beam is incident on the foil with a certain foil incident energy, the charged particle beam passes through the foil with one or more of the following transmittances: at least 5%, at least 10%, at least 20%, at least 30%, at least 50%, at least 70%, at least 80%, up to 95%, up to 75%, up to 60%, up to 40%, up to 25%, up to 15%, and / or up to 7%.

[0319] Example 152. A foil lens corrector as described in any example herein, particularly Example 151, wherein the incident energy of the foil is one or more of the following: at least 5 kiloelectron volts (keV), at least 7 keV, at least 10 keV, at least 15 keV, at least 20 keV, at least 30 keV, at least 50 keV, at least 70 keV, up to 80 keV, up to 60 keV, up to 40 keV, up to 25 keV, up to 17 keV, up to 12 keV, up to 8 keV, up to 6 keV, 5-8 keV, 7-12 keV, 5-15 keV, 5-20 keV, 5-30 keV, 5-40 keV, 5-60 keV, or 5-80 keV.

[0320] Example 153. A foil lens corrector as described in any of the examples herein, particularly any of Examples 143 to 152, wherein the electrode assembly is configured to generate the corrector electrostatic potential on the first side of the foil, and wherein the foil is configured to shield the corrector electrostatic potential such that the maximum amplitude of the corrector electrostatic potential generated by the electrode assembly on a second side of the foil opposite to the first side of the foil is at most 1% of the maximum amplitude of the corrector electrostatic potential on the first side of the foil.

[0321] Example 154. A foil lens corrector as described in any of the examples herein, particularly any of Examples 143 to 153, wherein the electrode assembly includes an electrode configured to generate at least a portion of the corrector electrostatic potential on a first side of the foil, and wherein the foil is configured to at least partially shield the corrector electrostatic potential from extending to a second side of the foil opposite to the first side of the foil.

[0322] Example 155. A foil lens corrector as described in any example herein, particularly any of Examples 143 to 154, wherein the electrode assembly comprises a first electrode and a second electrode, and wherein the foil lens corrector is configured to generate at least a portion of the corrector electrostatic potential by applying a first electrode voltage to the first electrode and a second electrode voltage to the second electrode, while the foil remains at a foil potential different from one or both of the first electrode voltage and the second electrode voltage.

[0323] Example 156. A foil lens corrector as described in any example herein, particularly Example 155, wherein each of the first electrode and the second electrode is located on the common side of the foil.

[0324] Example 157. A foil lens corrector as described in any of the examples herein, particularly any of Examples 143 to 156, wherein the electrode assembly is configured to generate the corrector electrostatic potential at an upstream location on the foil.

[0325] Example 158. A foil lens corrector as described in any of the examples herein, particularly any of Examples 143 to 157, wherein the electrode assembly is configured to generate the corrector electrostatic potential at a location downstream of the foil.

[0326] Example 159. A foil lens corrector as described in any of the examples herein, particularly any of Examples 143 to 158, wherein the CPM system includes a booster tube configured to accelerate the charged particle beam within at least a portion of the CPM system, and wherein at least a portion of the foil lens corrector is electrically coupled to the booster tube.

[0327] Example 160. A foil lens corrector as described in any of the examples herein, particularly Example 159, wherein the foil is electrically coupled to the booster tube.

[0328] Example 161. The foil lens corrector as described in any of the examples herein, particularly any of Examples 159 to 160, further includes a corrector housing that electrically couples the booster tube to the foil.

[0329] Example 162. A foil lens corrector as described in any of the examples herein, particularly any of Examples 159 to 161, wherein the foil lens corrector is configured within a booster tube.

[0330] Example 163. A foil lens corrector as described in any of the examples herein, particularly any of Examples 159 to 162, wherein the booster tube is configured to accelerate the charged particle beam to an enhanced potential along the optical axis within the booster tube, and wherein the foil lens corrector is configured such that the total electrostatic potential amplitude along the optical axis within the foil lens corrector is less than the amplitude of the enhanced potential.

[0331] Example 164. The foil lens corrector as described in any example herein, particularly Example 163, wherein the enhancement potential can be one or more of the following: at least 4 keV, at least 6 keV, at least 8 keV, at least 10 keV, at least 12 keV, up to 14 keV, up to 11 keV, up to 9 keV, up to 7 keV, up to 5 keV, 4-9 keV, 6-11 keV, 8-14 keV, or 4-14 keV.

[0332] Example 165. The foil lens corrector as described in any of the examples herein, particularly any of Examples 143 to 164, further includes a shielding electrode defining a foil aperture, wherein the foil spans the foil aperture.

[0333] Example 166. A foil lens corrector as described in any of the examples herein, particularly Example 165, wherein the foil completely covers the foil aperture.

[0334] Example 167. A foil lens corrector as described in any of the examples herein, particularly any of Examples 165 to 166, wherein the foil aperture is a circular aperture.

[0335] Example 168. A foil lens corrector as described in any of the examples herein, particularly any of Examples 165 to 167, wherein the foil aperture diameter is one or more of the following: at least 50 µm, at least 100 µm, at least 200 µm, at least 300 µm, at least 500 µm, at most 700 µm, at most 400 µm, at most 250 µm, at most 150 µm, or at most 75 µm.

[0336] Example 169. A foil lens corrector as described in any of the examples herein, particularly any of Examples 165 to 168, wherein the foil independently spans the foil aperture.

[0337] Example 170. A foil lens corrector as described in any of the examples herein, particularly any of Examples 165 to 169, wherein the foil is supported by a foil support structure that at least partially spans the foil aperture.

[0338] Example 171. A foil lens corrector as described in any of the examples herein, particularly Example 170, wherein the foil support structure comprises one or more of a carrier mesh, a grid, or a perforated structure.

[0339] Example 172. The foil lens corrector as described in any of the examples herein, particularly any of Examples 143 to 171, further comprises one or both of the following: (i) a first shielding electrode supporting the foil; and (ii) a second shielding electrode positioning the electrode assembly between the first and second shielding electrodes.

[0340] Example 173. A foil lens corrector as described in any example herein, particularly Example 172, wherein the second shielding electrode is electrically coupled to the first shielding electrode.

[0341] Example 174. A foil lens corrector as described in any of the examples herein, particularly Examples 172 to 173, wherein the first shielding electrode includes a foil aperture at least partially covered by the foil, and wherein the second shielding electrode includes a second aperture axially aligned with the foil aperture.

[0342] Example 175. The foil lens corrector as described in any of the examples herein, particularly any of Examples 143 to 174, further includes a corrector housing supporting at least one or both of the foil and the electrode assembly.

[0343] Example 176. A foil lens corrector as described in any example herein, particularly Example 175, wherein the electrode assembly comprises one or more electrodes configured to generate at least a portion of the corrector's electrostatic potential, and wherein one or more of the electrodes are electrically insulated from the corrector housing.

[0344] Example 177. The foil lens corrector as described in any of the examples herein, particularly any of Examples 175 to 176, further includes an insulating support that supports one or more of the electrodes relative to the corrector housing and electrically insulates the one or more of the electrodes from the corrector housing.

[0345] Example 178. A foil lens corrector as described in any of the examples herein, particularly any of Examples 174 to 177, wherein the electrode assembly comprises one or more electrodes configured to generate at least a portion of the corrector's electrostatic potential, and wherein the corrector housing at least partially supports one or more of the electrodes within the corrector housing.

[0346] Example 179. A foil lens corrector as described in any of the examples herein, particularly any of Examples 175 to 178, wherein the corrector housing includes a foil aperture, and wherein the foil is coupled to the corrector housing and covers the foil aperture.

[0347] Example 180. A foil lens corrector as described in any of the examples herein, particularly Example 179, wherein the foil completely covers the foil aperture.

[0348] Example 181. A foil lens corrector as described in any of the examples herein, particularly any of Examples 179 to 180, wherein the foil aperture is a circular aperture.

[0349] Example 182. A foil lens corrector as described in any of the examples herein, particularly any of Examples 179 to 181, wherein the foil aperture diameter is one or more of the following: at least 50 µm, at least 100 µm, at least 200 µm, at least 300 µm, at least 500 µm, up to 700 µm, up to 400 µm, up to 250 µm, up to 150 µm, or up to 75 µm.

[0350] Example 183. A foil lens corrector as described in any of the examples herein, particularly any of Examples 179 to 182, wherein the corrector housing comprises one or both of the following: (i) a first shielding electrode supporting the foil; and (ii) a second shielding electrode that positions the electrode assembly between the first and second shielding electrodes.

[0351] Example 184. A foil lens corrector as described in any example herein, particularly Example 183, wherein one or both of the first shielding electrode and the second shielding electrode are configured to form the corrector electrostatic potential within the corrector housing and to at least partially confine the corrector electrostatic potential within the corrector housing.

[0352] Example 185. A foil lens corrector as described in any of the examples herein, particularly any of Examples 183 to 184, wherein the second shielding electrode is electrically coupled to the first shielding electrode.

[0353] Example 186. A foil lens corrector as described in any of the examples herein, particularly any of Examples 183 to 185, wherein the corrector housing comprises a housing that is in direct contact with each of the first shielding electrode and the second shielding electrode.

[0354] Example 187. A foil lens corrector as described in any of the examples herein, particularly any of Examples 183 to 186, wherein the first shielding electrode comprises a foil aperture.

[0355] Example 188. A foil lens corrector as described in any example herein, particularly Example 187, wherein the second shielding electrode includes a second aperture axially aligned with the foil aperture.

[0356] Example 189. The foil lens corrector as described in any of the examples herein, particularly any of Examples 143 to 188, further includes a corrector heater configured to heat the foil.

[0357] Example 190. A foil lens corrector as described in any example herein, particularly Example 189, wherein the corrector heater is configured to heat the foil to a temperature of approximately 300°C.

[0358] Example 191. A foil lens corrector as described in any of the examples herein, particularly any of Examples 189 to 190, wherein the corrector heater is configured to heat the foil during operation of the foil lens corrector.

[0359] Example 192. A foil lens corrector as described in any of the examples herein, particularly any of Examples 189 to 191, wherein the corrector heater is configured to heat the foil during operation of the CPM system.

[0360] Example 193. A foil lens corrector as described in any of the examples herein, particularly any of Examples 189 to 192, wherein the corrector heater includes a heating element configured to receive current and a heater body, and wherein the heating element is thermally coupled to the foil through the heater body.

[0361] Example 194. A foil lens corrector as described in any example herein, particularly Example 193, wherein the heater body comprises an electrically insulating portion and a conductive portion.

[0362] Example 195. A foil lens corrector as described in any of the examples herein, particularly any of Examples 193 to 194, wherein the electrically insulating portion is in direct contact with each of the heating element and the conductive portion.

[0363] Example 196. A foil lens corrector as described in any of the examples herein, particularly any of Examples 193 to 195, wherein the electrically insulating portion comprises aluminum nitride.

[0364] Example 197. A foil lens corrector as described in any of the examples herein, particularly any of Examples 193 to 196, wherein the conductive portion is in direct contact with the foil.

[0365] Example 198. The foil lens corrector as described in any of the examples herein, particularly any of Examples 193 to 197, further includes a corrector housing that supports at least one or both of the foil and / or the electrode assembly, and wherein the conductive portion is in direct contact with the corrector housing.

[0366] Example 199. A foil lens corrector as described in any of the examples herein, particularly any of Examples 193 to 198, wherein the conductive portion comprises molybdenum.

[0367] Example 200. A foil lens corrector as described in any of the examples herein, particularly any of Examples 193 to 199, wherein the conductive portion defines at least a portion of a heater conduit configured to allow the charged particle beam to pass through the heater body.

[0368] Example 201. A foil lens corrector as described in any of the examples herein, particularly any of Examples 193 to 200, wherein the heater body electrically isolates the heating element from one or both of the foil and the corrector housing.

[0369] Example 202. A foil lens corrector as described in any of the examples herein, particularly any of Examples 193 to 201, wherein the heater body comprises aluminum nitride.

[0370] Example 203. A foil lens corrector as described in any of the examples herein, particularly any of Examples 193 to 202, wherein the heater body is in direct contact with one or both of the foil and the corrector housing.

[0371] Example 204. A foil lens corrector as described in any of the examples herein, particularly any of Examples 193 to 203, wherein the heating element is spaced apart from one or both of the foil and the corrector housing.

[0372] Example 205. A foil lens corrector as described in any of the examples herein, particularly any of Examples 193 to 204, wherein one or both of the heating element and the heater body define at least a portion of a heater conduit configured to allow the charged particle beam to pass through one or both of the corrector heater and the heater body.

[0373] Example 206. The foil lens corrector as described in any of the examples herein, particularly any of Examples 193 to 205, further includes a corrector housing that supports at least one or both of the foil and / or the electrode assembly, wherein the corrector housing defines a housing recess extending toward the electrode assembly, and wherein at least a portion of the corrector heater is received within the housing recess.

[0374] Example 207. A foil lens corrector as described in any of the examples herein, particularly any of Examples 143 to 206, wherein the CPM system comprises a scanning electron microscope (SEM).

[0375] Example 208. A foil lens corrector as described in any of the examples herein, particularly any of Examples 143 to 207, wherein the CPM system comprises a transmission electron microscope (TEM).

[0376] Example 209. A foil lens corrector as described in any of the examples herein, particularly any of Examples 143 to 208, wherein the CPM system includes one or more scanning deflectors configured to scan the charged particle beam relative to a sample, and wherein the foil lens corrector is located upstream of one or more of the scanning deflectors.

[0377] Example 210. A foil lens corrector as described in any of the examples herein, particularly any of Examples 143 to 209, wherein the CPM system includes an objective lens assembly, and wherein the foil lens corrector is located upstream of at least a portion of the objective lens assembly.

[0378] Example 211. A foil lens corrector as described in any of the examples herein, particularly any of Examples 143 to 210, wherein the CPM system includes a condenser lens assembly, and wherein the foil lens corrector is located downstream of at least a portion of the condenser lens assembly.

[0379] Example 212. A CPM system comprising: a charged particle source configured to generate a charged particle beam; and a foil lens corrector for correcting spherical aberration in the charged particle beam, wherein the foil lens corrector is any of the examples herein, and more particularly, any of the examples 1 to 211.

[0380] Example 213. A CPM system as described in any of the examples herein, particularly Example 212, wherein the CPM system includes SEM.

[0381] Example 214. A CPM system as described in any of the examples herein, particularly any of Examples 212 to 213, wherein the CPM system comprises a TEM.

[0382] Example 215. The CPM system described in any of the examples herein, particularly any of Examples 212 to 214, further includes an objective assembly configured to focus the charged particle beam onto a sample, wherein the foil lens corrector is located upstream of at least a portion of the objective assembly.

[0383] Example 216. The CPM system described in any of the examples herein, particularly any of Examples 212 to 215, further includes one or more scanning deflectors configured to scan the charged particle beam relative to the sample, and wherein the foil lens corrector is located upstream of one or more of the scanning deflectors.

[0384] Example 217. The CPM system described in any of the examples herein, particularly any of Examples 212 to 216, further includes a condenser lens assembly, wherein the foil lens corrector is located downstream of at least a portion of the condenser lens assembly.

[0385] Example 218. The CPM system described in any of the examples herein, particularly any of Examples 212 to 217, further includes an energy selection device configured to transmit only a portion of the charged particle beam having charged particle energy within a selected energy bandwidth.

[0386] Example 219. A CPM system as described in any of the examples herein, particularly Example 218, wherein the energy selection device comprises a monochromator.

[0387] Example 220. The CPM system described in any of the examples herein, particularly any of Examples 212 to 219, further includes a booster tube configured to accelerate the charged particle beam within at least a portion of the CPM system, wherein the foil lens corrector is at least partially located within the booster tube.

[0388] Example 221. A CPM system as described in any of the examples herein, particularly Example 220, wherein the charged particle beam comprises an electron beam, and wherein the booster tube is configured to be maintained at a positive voltage.

[0389] Example 222. A CPM system as described in any of the examples herein, particularly any of Examples 220 to 221, wherein the foil is electrically coupled to the booster tube.

[0390] Example 223. A CPM system as described in any of the examples herein, particularly any of Examples 220 to 222, wherein the foil lens corrector includes a corrector housing supporting the foil, and wherein the corrector housing electrically couples the booster tube to the foil.

[0391] Example 224. A CPM system as described in any of the examples, specifically any of Examples 220 to 223, wherein the booster tube is configured to accelerate the charged particle beam to an enhanced potential within the booster tube, and wherein the foil lens corrector is configured such that the corrector electrostatic potential reduces the magnitude of the total electrostatic potential along the optical axis within the corrector housing to less than the magnitude of the enhanced potential.

[0392] Example 225. The CPM system as described in any example herein, particularly Example 224, wherein the enhanced potential can be one or more of the following: at least 4 keV, at least 6 keV, at least 8 keV, at least 10 keV, at least 12 keV, up to 14 keV, up to 11 keV, up to 9 keV, up to 7 keV, up to 5 keV, 4-9 keV, 6-11 keV, 8-14 keV, or 4-14 keV.

[0393] Example 226. A CPM system as described in any of the examples herein, particularly any of Examples 212 to 225, wherein the CPM system is configured to guide the charged particle beam to a sample plane, and wherein the CPM system is configured such that the charged particle beam has one or more of the following sample incident energies in the sample plane: at least 10 eV, at least 50 eV, at least 100 eV, at least 300 eV, at least 500 eV, at least 1000 eV, at least 5000 eV, at least 10 keV, up to 50 keV, up to 30 keV, up to 7000 eV, up to 2000 eV, up to 1500 eV, up to 700 eV, up to 200 eV, up to 70 eV, up to 20 eV, 10-100 eV, 50-500 eV, 100-1000 eV, 300-1500 eV, 500-2000 eV. eV, 1000 eV-30 keV or 5000 eV-50 keV.

[0394] Example 227. A CPM system as described in any of the examples herein, particularly any of Examples 212 to 226, wherein the CPM system is configured to guide the charged particle beam to a sample plane, the beam current being one or more of the following: at least 10 picoamperes (pA), at least 30 pA, at least 50 pA, at least 100 pA, at least 300 pA, at least 500 pA, at least 1000 pA, up to 2000 pA, up to 700 pA, up to 400 pA, up to 200 pA, up to 70 pA, up to 40 pA, or up to 20 pA.

[0395] Example 228. A CPM system as described in any of the examples herein, particularly any of Examples 212 to 227, wherein the CPM system is configured to scan the charged particle beam over a sample to produce one or more of the following fields of view: at least 50 nanometers (nm), at least 100 nm, at least 200 nm, at least 300 nm, up to 500 nm, up to 250 nm, up to 150 nm, or up to 75 nm.

[0396] Example 229. A CPM system described in any example of this document, specifically any of Examples 212 to 228, wherein the CPM system is configured to focus the charged particle beam into a point in a sample plane, the characteristic beam diameter of the point being one or more of the following: at least 0.2 nm, at least 0.5 nm, at least 1 nm, at least 3 nm, at least 5 nm, up to 10 nm, up to 4 nm, up to 2 nm, up to 0.7 nm, up to 0.2 nm, 0.2-1 nm, 0.5-5 nm, or 1-10 nm.

[0397] Example 230. A CPM system as described in any of the examples herein, particularly any of Examples 212 to 229, wherein the CPM system is configured such that the charged particle beam has spherical aberration in the sample plane, the spherical aberration being characterized by third-order spherical aberration coefficients having a size of one or more of the following: up to 5 mm, up to 3 mm, up to 1 mm, up to 0.5 mm, or 0 mm.

[0398] Example 231. A method of operating a CPM system including a foil lens corrector, the method comprising: guiding a beam of charged particles along an optical axis to a sample located in a sample plane; and operating a foil lens corrector positioned along the optical axis to generate a corrector electrostatic potential that produces canceling spherical aberration in the beam of charged particles, wherein the foil lens corrector is any of the examples herein, and more particularly, any of the examples 1 to 211.

[0399] Example 232. The method as described in any example herein, particularly Example 231, wherein operating the foil lens corrector comprises directing the charged particle beam onto the foil such that the charged particle beam is incident on the foil at one or more of the following foil incident energies: at least 5 keV, at least 7 keV, at least 10 keV, at least 15 keV, at least 20 keV, at least 30 keV, at least 50 keV, at least 70 keV, up to 80 keV, up to 60 keV, up to 40 keV, up to 25 keV, up to 17 keV, up to 12 keV, up to 8 keV, up to 6 keV, 5-8 keV, 7-12 keV, 5-15 keV, 5-20 keV, 5-30 keV, 5-40 keV, 5-60 keV, or 5-80 keV.

[0400] Example 233. The method as described in any example herein, particularly any of Examples 231 to 232, wherein operating the foil lens corrector comprises transmitting the charged particle beam through the foil at one or more of the following transmittances: at least 5%, at least 10%, at least 20%, at least 30%, at least 50%, at least 70%, at least 80%, up to 95%, up to 75%, up to 60%, up to 40%, up to 25%, up to 15%, or up to 7%.

[0401] Example 234. The method as described in any of the examples herein, particularly any of Examples 231 to 233, wherein operating the foil lens corrector comprises the operation of making the canceling spherical aberration opposite in sign and at least substantially equal in magnitude to the spherical aberration component of the charged particle beam at the sample plane when the foil lens corrector is removed from the CPM system.

[0402] Example 235. The method described in any of the examples herein, particularly any of Examples 231 to 234, wherein the offsetting spherical aberration is characterized by negative spherical aberration coefficients.

[0403] Example 236. The method described in any of the examples herein, particularly any of Examples 231 to 235, wherein the offsetting spherical aberration is characterized by positive spherical aberration coefficients.

[0404] Example 237. The method described in any of the examples herein, particularly any of Examples 231 to 236, wherein operating the foil lens corrector comprises generating the corrector electrostatic potential using the electrode assembly.

[0405] Example 238. The method as described in any example herein, particularly Example 237, wherein generating the corrector electrostatic potential comprises generating a corrector electrostatic potential that is at least substantially confined to the first side of the foil.

[0406] Example 239. The method as described in any of the examples herein, particularly any of Examples 237 to 238, wherein the foil lens corrector comprises electrodes, and wherein generating the corrector electrostatic potential comprises applying a voltage to the electrodes.

[0407] Example 240. The method as described in any of the examples herein, particularly any of Examples 237 to 239, wherein the electrode assembly comprises a first electrode and a second electrode, and wherein generating the corrector electrostatic potential comprises applying a first voltage to the first electrode and applying a second voltage to the second electrode.

[0408] Example 241. The method described in any of the examples herein, particularly Example 240, further includes determining one or both of the first voltage and the second voltage.

[0409] Example 242. The method as described in any of the examples herein, particularly any of Examples 240 to 241, further comprises determining a combination of the first voltage and the second voltage that will produce the canceling spherical aberration in the charged particle beam.

[0410] Example 243. The method described in any of the examples herein, particularly any of Examples 240 to 242, further comprises: applying a predetermined first voltage to the first electrode; maintaining the first electrode at the predetermined first voltage and changing a second voltage applied to the second electrode; measuring characteristic beam properties of the charged particle beam corresponding to each second voltage as the second voltage changes; and selecting a preferred second voltage corresponding to a preferred value of the characteristic beam properties.

[0411] Example 244. The method as described in any example herein, particularly Example 243, wherein the characteristic beam property comprises one or both of the characteristic beam diameter of the charged particle beam in the sample plane and the spherical aberration of the charged particle beam in the sample plane.

[0412] Example 245. The method as described in any of the examples herein, particularly any of Examples 243 to 244, wherein the first voltage is the predetermined first voltage, and wherein the second voltage is the preferred second voltage.

[0413] Example 246. The method as described in any of the examples herein, particularly any of Examples 231 to 245, wherein the CPM system includes a booster tube configured to accelerate the charged particle beam within at least a portion of the CPM system, and wherein the method further includes applying a booster tube voltage to the booster tube.

[0414] Example 247. The method described in any example herein, particularly Example 246, wherein the booster voltage is one or more of the following: at least 5 kV, at least 7 kV, at least 10 kV, up to 12 kV, up to 8 kV, up to 6 kV, 5-8 kV, 7-12 kV, or 5-12 kV.

[0415] Example 248. The method described in any of the examples herein, particularly any of Examples 231 to 247, further comprises heating the foil with a calibrator heater.

[0416] Example 249. The method as described in any example herein, particularly Example 248, wherein heating the foil comprises heating the foil to a temperature of approximately 300°C.

[0417] Example 250. The method as described in any of the examples herein, particularly any of Examples 248 to 249, wherein heating the foil comprises transferring thermal energy from the heating element of the calibrator heater to the foil via a heater body that electrically isolates the heating element from the foil.

[0418] Example 251. The method as described in any of the examples herein, particularly Example 250, wherein the heater body comprises an electrically insulating portion and a conductive portion.

[0419] Example 252. The method as described in any of the examples herein, particularly any of Examples 250 to 251, wherein the electrically insulating portion is in direct contact with each of the heating element and the conductive portion.

[0420] Example 253. The method described in any of the examples herein, particularly any of Examples 250 to 252, wherein the electrically insulating portion comprises aluminum nitride.

[0421] Example 254. The method as described in any of the examples herein, particularly any of Examples 250 to 253, wherein the conductive portion is in direct contact with the foil.

[0422] Example 255. The method described in any of the examples herein, particularly any of Examples 250 to 254, further includes a calibrator housing that supports at least one or both of the foil and / or the electrode assembly, and wherein the conductive portion is in direct contact with the calibrator housing.

[0423] Example 256. The method as described in any of the examples herein, particularly any of Examples 250 to 255, wherein the conductive portion comprises molybdenum.

[0424] Example 257. The method as described in any of the examples herein, particularly any of Examples 250 to 256, wherein the conductive portion defines at least a portion of a heater conduit configured to allow the charged particle beam to pass through the heater body.

[0425] Example 258. The method as described in any of the examples herein, particularly any of Examples 248 to 257, wherein the foil is heated with the corrector heater before the charged particle beam is directed to the sample.

[0426] Example 259. The method described in any of the examples herein, particularly any of Examples 231 to 258, wherein guiding the charged particle beam to the sample comprises scanning the charged particle beam relative to the sample using one or more scanning deflectors of the CPM system.

[0427] Example 260. The method as described in any example herein, particularly Example 259, wherein the scanning charged particle beam comprises scanning the charged particle beam in a region of linear size one or more of the following: at least 50 nm, at least 100 nm, at least 200 nm, at least 300 nm, at least 500 nm, at least 1000 nm, up to 1200 nm, up to 700 nm, up to 250 nm, up to 150 nm, or up to 75 nm.

[0428] Example 261. The method described in any example of this document, and more particularly in any of Examples 231 to 260, wherein guiding the charged particle beam to the sample comprises focusing the charged particle beam into a point in the sample plane, the characteristic diameter of the point being one or more of the following: at least 0.1 nm, at least 0.5 nm, at least 1 nm, at least 3 nm, at least 5 nm, up to 10 nm, up to 4 nm, up to 2 nm, up to 0.7 nm, up to 0.2 nm, 0.2-1 nm, 0.5-5 nm, or 1-10 nm.

[0429] Example 262. As described in any of the examples herein, particularly any of Examples 231 to 261, guiding the charged particle beam to the sample comprises such that the charged particle beam has spherical aberration in the sample plane, the spherical aberration being characterized by third-order spherical aberration coefficients having a size of one or more of the following: up to 5 mm, up to 3 mm, up to 1 mm, up to 0.5 mm, or 0 mm.

[0430] Example 263. A method of operating a CPM system including a foil lens corrector, the method comprising: guiding a charged particle beam along an optical axis to a sample located in a sample plane; and operating the foil lens corrector positioned along the optical axis to generate a corrector electrostatic potential that produces a counteracting spherical aberration in the charged particle beam, wherein operating the foil lens corrector comprises guiding the charged particle beam to a foil of the foil lens corrector such that: (i) the charged particle beam is incident on the foil with a foil incident energy of at least 5 keV and at most 80 keV; and (ii) the charged particle beam is transmitted through the foil with a transmittance of at least 20%.

[0431] Example 264. The method as described in any example herein, particularly Example 263, wherein operating the foil lens corrector comprises the operation of making the canceling spherical aberration opposite in sign and at least substantially equal in magnitude to the spherical aberration component of the charged particle beam at the sample plane when the foil lens corrector is removed from the CPM system.

[0432] Example 265. The method described in any of the examples herein, particularly any of Examples 263 to 264, wherein the offsetting spherical aberration is characterized by negative spherical aberration coefficients.

[0433] Example 266. The method described in any of the examples herein, particularly any of Examples 263 to 265, wherein the offsetting spherical aberration is characterized by positive spherical aberration coefficients.

[0434] Example 267. The method as described in any of the examples herein, particularly any of Examples 263 to 266, wherein operating the foil lens corrector comprises generating the corrector electrostatic potential using the electrode assembly of the foil lens corrector.

[0435] Example 268. The method as described in any example herein, particularly Example 267, wherein generating the corrector electrostatic potential comprises generating a corrector electrostatic potential that is at least substantially confined to a first side of the foil of the foil lens corrector.

[0436] Example 269. The method as described in any of the examples herein, particularly any of Examples 267 to 268, wherein the foil lens corrector comprises electrodes, and wherein generating the corrector electrostatic potential comprises applying a voltage to the electrodes.

[0437] Example 270. The method as described in any of the examples herein, particularly any of Examples 267 to 269, wherein the electrode assembly comprises a first electrode and a second electrode, and wherein generating the corrector electrostatic potential comprises applying a first voltage to the first electrode and applying a second voltage to the second electrode.

[0438] Example 271. The method described in any of the examples herein, particularly Example 270, further includes determining one or both of the first voltage and the second voltage.

[0439] Example 272. The method described in any of the examples herein, particularly any of Examples 270 to 271, further comprises determining a combination of the first voltage and the second voltage that will produce the canceling spherical aberration in the charged particle beam.

[0440] Example 273. The method described in any of the examples herein, particularly any of Examples 270 to 272, further comprises: applying a predetermined first voltage to the first electrode; maintaining the first electrode at the predetermined first voltage and changing a second voltage applied to the second electrode; measuring characteristic beam properties of the charged particle beam corresponding to each second voltage as the second voltage changes; and selecting a preferred second voltage corresponding to a preferred value of the characteristic beam properties.

[0441] Example 274. The method as described in any example herein, particularly Example 273, wherein the characteristic beam property comprises one or both of the characteristic beam diameter of the charged particle beam in the sample plane and the spherical aberration of the charged particle beam in the sample plane.

[0442] Example 275. The method as described in any of the examples herein, particularly any of Examples 273 to 274, wherein the first voltage is the predetermined first voltage, and wherein the second voltage is the preferred second voltage.

[0443] Example 276. The method as described in any of the examples herein, particularly any of Examples 273 to 275, wherein the CPM system includes a booster tube configured to accelerate the charged particle beam within at least a portion of the CPM system, and wherein the method further includes applying a booster tube voltage to the booster tube.

[0444] Example 277. The method described in any example herein, particularly Example 276, wherein the booster voltage is one or more of the following: at least 5 kV, at least 7 kV, at least 10 kV, at most 12 kV, at most 8 kV, at most 6 kV, 5-8 kV, 7-12 kV, or 5-12 kV.

[0445] Example 278. The method described in any of the examples herein, particularly any of Examples 263 to 277, further comprises heating the foil of the foil lens corrector with a corrector heater.

[0446] Example 279. The method as described in any of the examples herein, particularly Example 278, wherein heating the foil comprises heating the foil to a temperature of approximately 300°C.

[0447] Example 280. The method as described in any of the examples herein, particularly any of Examples 278 to 279, wherein heating the foil comprises transferring thermal energy from the heating element of the calibrator heater to the foil via a heater body that electrically isolates the heating element from the foil.

[0448] Example 281. The method as described in any of the examples herein, particularly Example 280, wherein the heater body comprises an electrically insulating portion and a conductive portion.

[0449] Example 282. The method as described in any of the examples herein, particularly any of Examples 280 to 281, wherein the electrically insulating portion is in direct contact with each of the heating element and the conductive portion.

[0450] Example 283. The method described in any of the examples herein, particularly any of Examples 280 to 282, wherein the electrically insulating portion comprises aluminum nitride.

[0451] Example 284. The method as described in any of the examples herein, particularly any of Examples 280 to 283, wherein the conductive portion is in direct contact with the foil.

[0452] Example 285. The method described in any of the examples herein, particularly any of Examples 280 to 284, further includes a corrector housing that supports at least one or both of the foil and / or the foil lens corrector electrode assembly, and wherein the conductive portion is in direct contact with the corrector housing.

[0453] Example 286. The method as described in any of the examples herein, particularly any of Examples 280 to 285, wherein the conductive portion comprises molybdenum.

[0454] Example 287. The method as described in any of the examples herein, particularly any of Examples 280 to 286, wherein the conductive portion defines at least a portion of a heater conduit configured to allow the charged particle beam to pass through the heater body.

[0455] Example 288. The method as described in any of the examples herein, particularly any of Examples 278 to 287, wherein the foil is heated with the corrector heater before the charged particle beam is directed to the sample.

[0456] Example 289. The method as described in any of the examples herein, particularly any of Examples 273 to 288, wherein guiding the charged particle beam to the sample comprises scanning the charged particle beam relative to the sample using one or more scanning deflectors of the CPM system.

[0457] Example 290. The method as described in any example herein, particularly Example 289, wherein the scanning charged particle beam comprises scanning the charged particle beam in a region of linear size one or more of the following: at least 50 nm, at least 100 nm, at least 200 nm, at least 300 nm, at least 500 nm, at least 1000 nm, at least 1200 nm, up to 700 nm, up to 250 nm, up to 150 nm, or up to 75 nm.

[0458] Example 291. The method described in any example of this document, and more particularly in any of Examples 273 to 290, wherein guiding the charged particle beam to the sample comprises focusing the charged particle beam into a point in the sample plane, the characteristic diameter of the point being one or more of the following: at least 0.1 nm, at least 0.5 nm, at least 1 nm, at least 3 nm, at least 5 nm, up to 10 nm, up to 4 nm, up to 2 nm, up to 0.7 nm, up to 0.2 nm, 0.2-1 nm, 0.5-5 nm, or 1-10 nm.

[0459] Example 292. As in any example herein, particularly any of Examples 273 to 291, the method of guiding the charged particle beam to the sample comprises such that the charged particle beam has spherical aberration in the sample plane, the spherical aberration being characterized by third-order spherical aberration coefficients having a size of one or more of the following: up to 5 mm, up to 3 mm, up to 1 mm, up to 0.5 mm, or 0 mm.

[0460] Example 293. A method of operating a CPM system including a foil lens corrector, the method comprising: guiding a charged particle beam along an optical axis to a sample located in a sample plane; and operating a foil lens corrector positioned along the optical axis as a converging lens to generate a corrector electrostatic potential, the corrector electrostatic potential generating counteracting spherical aberration in the charged particle beam, wherein the foil lens corrector includes a foil and an electrode assembly, and wherein operating the foil lens corrector comprises using the electrode assembly to generate the corrector electrostatic potential only on a first side of the foil.

[0461] Example 294. The method as described in any example herein, particularly Example 293, wherein operating the foil lens corrector comprises directing the charged particle beam onto the foil such that the charged particle beam is incident on the foil at one or more of the following foil incident energies: at least 5 keV, at least 7 keV, at least 10 keV, at least 15 keV, at least 20 keV, at least 30 keV, at least 50 keV, at least 70 keV, up to 80 keV, up to 60 keV, up to 40 keV, up to 25 keV, up to 17 keV, up to 12 keV, up to 8 keV, up to 6 keV, 5-8 keV, 7-12 keV, 5-15 keV, 5-20 keV, 5-30 keV, 5-40 keV, 5-60 keV, or 5-80 keV.

[0462] Example 295. The method as described in any example herein, particularly any of Examples 293 to 294, wherein operating the foil lens corrector comprises transmitting the charged particle beam through the foil at one or more of the following transmittances: at least 5%, at least 10%, at least 20%, at least 30%, at least 50%, at least 70%, at least 80%, up to 95%, up to 75%, up to 60%, up to 40%, up to 25%, up to 15%, and / or up to 7%.

[0463] Example 296. The method as described in any of the examples herein, particularly any of Examples 293 to 295, wherein operating the foil lens corrector comprises the operation of making the canceling spherical aberration opposite in sign and at least substantially equal in magnitude to the spherical aberration component of the charged particle beam at the sample plane when the foil lens corrector is removed from the CPM system.

[0464] Example 297. The method described in any of the examples herein, particularly any of Examples 293 to 296, wherein the offsetting spherical aberration is characterized by negative spherical aberration coefficients.

[0465] Example 298. The method described in any of the examples herein, particularly any of Examples 293 to 297, wherein the offsetting spherical aberration is characterized by positive spherical aberration coefficients.

[0466] Example 299. The method described in any of the examples herein, particularly any of Examples 283 to 298, wherein operating the foil lens corrector comprises generating the corrector electrostatic potential using the electrode assembly.

[0467] Example 300. The method as described in any example herein, particularly Example 299, wherein generating the corrector electrostatic potential comprises generating a corrector electrostatic potential that is at least substantially confined to the first side of the foil.

[0468] Example 301. The method as described in any of the examples herein, particularly any of Examples 299 to 300, wherein the foil lens corrector comprises electrodes, and wherein generating the corrector electrostatic potential comprises applying a voltage to the electrodes.

[0469] Example 302. The method as described in any of the examples herein, particularly any of Examples 299 to 301, wherein the electrode assembly comprises a first electrode and a second electrode, and wherein generating the corrector electrostatic potential comprises applying a first voltage to the first electrode and applying a second voltage to the second electrode.

[0470] Example 303. The method described in any of the examples herein, particularly Example 302, further includes determining one or both of the first voltage and the second voltage.

[0471] Example 304. The method described in any of the examples herein, particularly any of Examples 302 to 303, further comprises determining a combination of the first voltage and the second voltage that will produce the canceling spherical aberration in the charged particle beam.

[0472] Example 305. The method described in any of the examples herein, particularly any of Examples 302 to 304, further comprises: applying a predetermined first voltage to the first electrode; maintaining the first electrode at the predetermined first voltage and changing a second voltage applied to the second electrode; measuring characteristic beam properties of the charged particle beam corresponding to each second voltage as the second voltage changes; and selecting a preferred second voltage corresponding to a preferred value of the characteristic beam properties.

[0473] Example 306. The method as described in any example herein, particularly Example 305, wherein the characteristic beam property comprises one or both of the characteristic beam diameter of the charged particle beam in the sample plane and the spherical aberration of the charged particle beam in the sample plane.

[0474] Example 307. The method as described in any of the examples herein, particularly any of Examples 305 to 306, wherein the first voltage is the predetermined first voltage, and wherein the second voltage is the preferred second voltage.

[0475] Example 308. The method as described in any of the examples herein, particularly any of Examples 293 to 307, wherein the CPM system includes a booster tube configured to accelerate the charged particle beam within at least a portion of the CPM system, and wherein the method further includes applying a booster tube voltage to the booster tube.

[0476] Example 309. The method described in any example herein, particularly Example 308, wherein the booster voltage is one or more of the following: at least 5 kV, at least 7 kV, at least 10 kV, at most 12 kV, at most 8 kV, at most 6 kV, 5-8 kV, 7-12 kV, or 5-12 kV.

[0477] Example 310. The method described in any of the examples herein, particularly any of Examples 293 to 309, further comprises heating the foil with a calibrator heater.

[0478] Example 311. The method as described in any example herein, particularly Example 310, wherein heating the foil comprises heating the foil to a temperature of approximately 300°C.

[0479] Example 312. The method as described in any of the examples herein, particularly any of Examples 310 to 311, wherein heating the foil comprises transferring thermal energy from the heating element of the calibrator heater to the foil via a heater body that electrically isolates the heating element from the foil.

[0480] Example 313. The method as described in any of the examples herein, particularly Example 312, wherein the heater body comprises an electrically insulating portion and a conductive portion.

[0481] Example 314. The method as described in any of the examples herein, particularly any of Examples 312 to 313, wherein the electrically insulating portion is in direct contact with each of the heating element and the conductive portion.

[0482] Example 315. The method as described in any of the examples herein, particularly any of Examples 312 to 314, wherein the electrically insulating portion comprises aluminum nitride.

[0483] Example 316. The method as described in any of the examples herein, particularly any of Examples 312 to 315, wherein the conductive portion is in direct contact with the foil.

[0484] Example 317. The method described in any of the examples herein, particularly any of Examples 312 to 316, further includes a calibrator housing that supports at least one or both of the foil and / or the electrode assembly, and wherein the conductive portion is in direct contact with the calibrator housing.

[0485] Example 318. The method as described in any of the examples herein, particularly any of Examples 312 to 317, wherein the conductive portion comprises molybdenum.

[0486] Example 319. The method as described in any of the examples herein, particularly any of Examples 312 to 318, wherein the conductive portion defines at least a portion of a heater conduit configured to allow the charged particle beam to pass through the heater body.

[0487] Example 320. The method as described in any of the examples herein, particularly any of Examples 310 to 319, wherein the foil is heated with the corrector heater before the charged particle beam is directed to the sample.

[0488] Example 321. The method as described in any of the examples herein, particularly any of Examples 293 to 320, wherein guiding the charged particle beam to the sample comprises scanning the charged particle beam relative to the sample using one or more scanning deflectors of the CPM system.

[0489] Example 322. The method as described in any example herein, particularly Example 321, wherein the scanning charged particle beam comprises scanning the charged particle beam in a region of linear size one or more of the following: at least 50 nm, at least 100 nm, at least 200 nm, at least 300 nm, at least 500 nm, at least 1000 nm, at most 1200 nm, at most 700 nm, at most 250 nm, at most 150 nm, or at most 75 nm.

[0490] Example 323. The method described in any example of this document, and more particularly in any of Examples 293 to 322, wherein guiding the charged particle beam to the sample comprises focusing the charged particle beam into a point in the sample plane, the characteristic diameter of the point being one or more of the following: at least 0.1 nm, at least 0.5 nm, at least 1 nm, at least 3 nm, at least 5 nm, up to 10 nm, up to 4 nm, up to 2 nm, up to 0.7 nm, up to 0.2 nm, 0.2-1 nm, 0.5-5 nm, or 1-10 nm.

[0491] Example 324. As described in any of the examples herein, particularly any of Examples 293 to 323, the method of guiding the charged particle beam to the sample comprises such that the charged particle beam has spherical aberration in the sample plane, the spherical aberration being characterized by third-order spherical aberration coefficients having a size of one or more of the following: up to 5 mm, up to 3 mm, up to 1 mm, up to 0.5 mm, or 0 mm.

[0492] Given the many possible examples to which the disclosed technical principles can be applied, it should be recognized that the examples shown are merely preferred examples and should not be considered as limiting the scope of the disclosed technology. Rather, the scope is defined by the appended claims. Therefore, we claim the full benefits within the scope of all these claims.

Claims

1. A foil lens corrector for correcting spherical aberration in a charged particle beam generated by a charged particle microscope (CPM) system, the foil lens corrector comprising: A foil configured to align with the optical axis of the CPM system; and Electrode assembly configured to generate the electrostatic potential of the corrector. The foil comprises graphene, the foil is configured to support space charge such that the optical axis intersects the space charge, and the foil lens corrector is configured such that the corrector electrostatic potential generates canceling spherical aberration in the charged particle beam to at least partially correct the spherical aberration in the charged particle beam.

2. The foil lens corrector according to claim 1, wherein the foil lens corrector is configured to act as a converging lens for the charged particle beam.

3. The foil lens corrector of claim 1, wherein the foil lens corrector is configured such that during operation of the CPM system, the charged particle beam is incident on the foil with a foil incident energy of at least 5 keV and at most 80 keV, and the charged particle beam is transmitted through the foil with a transmittance of at least 20%.

4. The foil lens corrector of claim 1, wherein the electrode assembly is configured to generate the corrector electrostatic potential on a first side of the foil, and wherein the foil is configured to shield the corrector electrostatic potential such that the maximum amplitude of the corrector electrostatic potential generated by the electrode assembly on a second side of the foil opposite to the first side of the foil is at most 1% of the maximum amplitude of the corrector electrostatic potential on the first side of the foil.

5. The foil lens corrector of claim 1, wherein the electrode assembly comprises a first electrode and a second electrode located on a common side of the foil, and wherein the foil lens corrector is configured to generate at least a portion of the corrector electrostatic potential by applying a first electrode voltage to the first electrode and a second electrode voltage to the second electrode, while the foil is maintained at a foil potential different from both the first electrode voltage and the second electrode voltage.

6. The foil lens corrector of claim 1 further comprises a shielding electrode defining a foil aperture with a diameter of at least 100 micrometers (µm), wherein the foil spans the foil aperture, and wherein the foil spans the foil aperture independently.

7. The foil lens corrector of claim 1, further comprising a corrector housing supporting at least one or both of the foil and the electrode assembly, wherein the electrode assembly includes one or more electrodes configured to generate at least a portion of the corrector electrostatic potential, and wherein the corrector housing at least partially supports the one or more electrodes within the corrector housing such that the one or more electrodes are electrically insulated from the corrector housing.

8. The foil lens corrector of claim 1, further comprising a corrector heater configured to heat the foil, wherein the corrector heater includes a heating element configured to receive current and a heater body, wherein the heating element is thermally coupled to the foil through the heater body, and wherein the heating element is electrically isolated from the foil.

9. A CPM system, comprising: A charged particle source, the charged particle source being configured to generate a beam of charged particles; and A foil lens corrector for correcting spherical aberration in a charged particle beam, the foil lens corrector comprising: A foil configured to align with the optical axis of the CPM system; and Electrode assembly configured to generate the electrostatic potential of the corrector. The foil comprises graphene, the foil is configured to support space charge such that the optical axis intersects the space charge, and the foil lens corrector is configured such that the corrector electrostatic potential generates canceling spherical aberration in the charged particle beam to at least partially correct the spherical aberration in the charged particle beam.

10. The CPM system of claim 9, wherein the CPM system comprises a scanning electron microscope (SEM).

11. The CPM system of claim 9, further comprising one or more scanning deflectors configured to scan the charged particle beam relative to a sample, wherein the foil lens corrector is located upstream of one or more of the scanning deflectors.

12. The CPM system of claim 9, further comprising a booster tube configured to accelerate the charged particle beam within at least a portion of the CPM system, wherein the foil lens corrector is at least partially located within the booster tube.

13. The CPM system of claim 12, wherein the foil is electrically coupled to the booster tube.

14. The CPM system of claim 12, wherein the booster tube is configured to accelerate the charged particle beam to an enhancement potential of at least 4 keV and at most 14 keV within the booster tube, and wherein the foil lens corrector is configured such that the corrector electrostatic potential reduces the amplitude of the total electrostatic potential along the optical axis within the corrector housing to less than the amplitude of the enhancement potential.

15. The CPM system of claim 9, wherein the CPM system is configured such that the charged particle beam has spherical aberration in the sample plane, the spherical aberration being characterized by a third-order spherical aberration coefficient having a magnitude of at most 1 mm.

16. A method for operating a CPM system, the method comprising: Guide the charged particle beam along the optical axis to the sample located in the sample plane; and A foil lens corrector positioned along the optical axis is operated to generate a corrector electrostatic potential that produces canceling spherical aberrations in the charged particle beam. Operating the foil lens corrector includes guiding the charged particle beam to the foil lens corrector with a foil, such that: The charged particle beam is incident on the foil with a foil incident energy of at least 5 keV and at most 80 keV; A beam of charged particles passes through the foil with a transmittance of at least 20%.

17. The method of claim 16, wherein operating the foil lens corrector comprises: making the canceling spherical aberration opposite in sign and at least substantially equal in magnitude to the spherical aberration component of the charged particle beam at the sample plane when the foil lens corrector is removed from the CPM system.

18. The method of claim 16, wherein operating the foil lens corrector comprises operating the foil lens corrector such that the electrostatic potential of the corrector is at least substantially confined to the first side of the foil.

19. The method of claim 18, wherein the electrode assembly comprises a first electrode and a second electrode, wherein generating the corrector electrostatic potential comprises applying a first voltage to the first electrode and applying a second voltage to the second electrode, and wherein the method further comprises determining a combination of the first voltage and the second voltage that will generate the canceling spherical aberration in the charged particle beam.

20. The method of claim 16, further comprising heating the foil with a calibrator heater before directing the charged particle beam to the sample.

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