Objective lens, charged particle microscope including objective lens, and related methods

Abstract

Objective lenses, charged particle microscopes including the objective lenses, and related methods are disclosed herein. The objective lens can include a lens body, a shield electrode, and a steering electrode. The objective lens is configured such that changing the control electrode voltage adjusts the position of the main object plane of the objective lens, thereby changing the focus working distance of the objective lens. A method can include positioning a sample relative to an objective lens, and operating the objective lens to focus a charged particle beam to a focus position.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to U.S. Non - provisional Application 18 / 534,547, filed on December 8, 2023, the entire disclosure of which is incorporated herein by reference. Technical field

[0003] The present disclosure generally relates to objective lenses for focusing charged particle beams in a charged particle microscope system and related methods. Background art

[0004] A probe system for evaluating the performance of an electronic device may include probes that are proximate to and / or in contact with local test locations on such a device. Such probes may be used to send test signals to and / or receive test signals from the device. As the physical size of such sample devices decreases, it is necessary to position such probes with a correspondingly increased precision. Thus, probe systems typically employ a charged particle microscope (CPM) system such as a scanning electron microscope (SEM) system to assist in positioning the probes relative to the sample test locations. In such examples, it is desirable to limit the landing energy of charged particles (e.g., electrons) on the sample device to protect the sample device from adverse effects from the charged particles. Summary of the invention

[0005] In a representative example, a device includes an objective lens having a lens body, a shielding electrode disposed within a downstream end region of the lens body, and a manipulation electrode disposed within the downstream end region of the lens body and upstream of the shielding electrode. The lens body extends circumferentially about an optical axis of the objective lens. The shielding electrode is configured to at least partially shield a test region downstream of the objective lens from a lens electrostatic field generated within the objective lens. The objective lens is configured such that changing a manipulation electrode voltage applied to the manipulation electrode adjusts a position of an objective plane of the objective lens in a downstream direction to increase a focusing working distance of the objective lens.

[0006] In some examples, the device further includes a charged particle source configured to emit a charged particle beam along an optical axis and toward a sample, and the objective lens is configured to focus the charged particle beam to a focusing position corresponding to a position of the sample.

[0007] In another representative example, the objective lens includes a shielding electrode and a manipulation electrode. The objective lens is configured to generate a lens electrostatic field to at least partially direct a charged particle beam along an optical axis to a focusing position, the charged particle beam having an impact energy measured at the focusing position, the impact energy being at most 100 electron volts (eV). The shielding electrode is configured to at least partially shield a test area downstream of the objective lens such that the lens electrostatic field has an axial electric field strength measured at the focusing position in a direction parallel to the optical axis of at most 150 volts per millimeter (V / mm). The manipulation electrode is configured to generate at least a portion of the lens electrostatic field such that the objective lens operates at a focusing working distance measured between the objective lens and the focusing position in a direction parallel to the lens central axis of the objective lens of 1 millimeter (mm) to 3 millimeters (mm).

[0008] In another representative example, a method includes: positioning a sample relative to an objective lens configured to focus a charged particle beam to a focusing position; and operating the objective lens. The objective lens includes a lens body, a shielding electrode disposed within a downstream end region of the lens body, and a manipulation electrode disposed within the downstream end region of the lens body and upstream of the shielding electrode. The lens body extends circumferentially around the lens central axis of the objective lens. The shielding electrode is configured to at least partially shield a test area downstream of the objective lens from a lens electrostatic field generated within the objective lens. Operating the objective lens includes controlling a focusing working distance between the objective lens and the focusing position by applying a manipulation electrode voltage to the manipulation electrode.

[0009] The foregoing and other objects, features, and advantages of the disclosed technology will become more apparent from the following detailed description taken in conjunction with the reference drawings. Description of the Drawings

[0010] Figure 1 is a schematic diagram of a CPM system according to one example.

[0011] Figure 2 is a cross-sectional view of an objective lens positioned relative to a sample and a pair of sample probes according to one example.

[0012] Figure 3 is a cross-sectional perspective view of an objective lens according to one example.

[0013] Figure 4A is a diagram of a simulation of a charged particle beam profile at a sample test position having an impact energy of 200 eV and not using a manipulation electrode according to one example.

[0014] Figure 4B is a diagram of a simulation of a charged particle beam profile at a sample test position having an impact energy of 80 eV and not using a manipulation electrode according to one example.

[0015] Figure 4C It is a diagram of a simulation of the charged particle beam profile at the sample test position with an impact energy of 200 eV according to an example and using a manipulation electrode.

[0016] Figure 4D It is a diagram of a simulation of the charged particle beam profile at the sample test position with an impact energy of 80 eV according to an example and using a manipulation electrode.

[0017] Figure 5A It is a diagram of the relationship between the characteristic beam diameter of a charged particle beam and the impact energy of the charged particle beam in a configuration where the objective lens generates an axial electrostatic field strength of 223 V / mm at the sample test position and no manipulation electrode is used, according to an example.

[0018] Figure 5B It is a diagram of the relationship between the characteristic beam diameter of a charged particle beam and the impact energy of the charged particle beam in a configuration where the objective lens generates an axial electrostatic field strength of 175 V / mm at the sample test position and no manipulation electrode is used, according to an example.

[0019] Figure 5C It is a diagram of the relationship between the characteristic beam diameter of a charged particle beam and the impact energy of the charged particle beam in a configuration where the objective lens generates an axial electrostatic field strength of 132 V / mm at the sample test position and no manipulation electrode is used, according to an example.

[0020] Figure 5D It is a diagram of the relationship between the characteristic beam diameter of a charged particle beam and the impact energy of the charged particle beam in a configuration where the objective lens generates an axial electrostatic field strength of 139 V / mm at the sample test position and a manipulation electrode is used, according to an example.

[0021] Figure 5E It is a diagram of the relationship between the characteristic beam diameter of a charged particle beam and the impact energy of the charged particle beam in a configuration where the objective lens generates an axial electrostatic field strength of 116 V / mm at the sample test position and a manipulation electrode is used, according to an example.

[0022] Figure 5F It is a diagram of the relationship between the characteristic beam diameter of a charged particle beam and the impact energy of the charged particle beam in a configuration where the objective lens generates an axial electrostatic field strength of 93 V / mm at the sample test position and a manipulation electrode is used, according to an example.

[0023] Figure 6 It is a flowchart depicting a method of assembling and / or operating a CPM system including an objective lens according to an example.

[0024] Figure 7Schematic diagram of a computing system that can be used to perform one or more methods of the present disclosure according to an example. Detailed Description

[0025] The present disclosure generally relates to CPM systems for imaging samples, such as can be used to facilitate positioning a sample probe relative to a test location on a sample with nanoscale precision. For example, electrical failure analysis (EFA) of existing technology integrated circuits typically involves positioning one or more sample probes near or in contact with a sample test location of a sample, which may have a feature size of less than 10 nanometers (nm). To position such sample probes with such precision, a CPM system such as an SEM system can be used to generate an image of the sample probe and / or the sample test location, enabling a user to visually determine and / or confirm the position of the sample probe relative to the sample test location. The SEM system can employ an electrostatic lens and / or a magnetic objective lens to focus a charged particle beam to a target focus location.

[0026] In the present disclosure, the term "sample" can refer to any of a variety of devices, components, and / or materials (such as for imaging thereof) to which a charged particle beam can be directed. For example, in the case of EFA, the sample can include and / or be an electrical device, such as a semiconductor substrate that supports a circuit to be tested. In such examples, the term "sample" can also be understood to include any other component to be imaged during EFA, such as a portion of the sample probe adjacent to the device under test.

[0027] When performing EFA, it is generally desirable to limit the impact energy of the electron beam hitting the sample to avoid damaging the sample by the electron beam. For example, the desired impact energy of the electron beam can be in the range of 50 electron volts (eV) to 200 electron volts. However, due to Coulomb interactions, stray fields, and charging effects in the SEM optical column, a low-energy electron beam can be prone to dispersion. Such effects can be mitigated by using a booster tube in the SEM optical column, which accelerates the electron beam within the booster tube and decelerates the electron beam when it exits the booster tube. The booster tube can effectively operate as an electrode of the objective lens with an associated electrostatic field, which decelerates and / or focuses the electron beam downstream of the booster tube.

[0028] The operation of the objective lens can be characterized by a working distance that separates the objective lens from the target focus position and / or by a focal length that separates the principal object plane of the objective lens from the target focus position. It is generally desirable to configure the objective lens such that the working distance is large enough to accommodate a sample probe between the objective lens and the sample. However, in some examples, the presence of the booster tube may limit the working distance and / or the focusing of the electron beam at the target focus position. For example, the electrostatic field generated by the booster tube to decelerate electrons downstream of the booster tube is also used to focus the electron beam, thereby creating an electrostatic lens. The electrostatic lens associated with the booster tube may cause the focus of the electron beam to undesirably approach the objective lens, thus limiting the maximum achievable operating working distance of the objective lens.

[0029] Limiting the working distance in this way can cause the focusing characteristics of the objective lens to be primarily affected by the electrostatic field generated by the objective lens rather than by the magnetic field generated by the objective lens. In some examples, magnetic lens focusing provides enhanced optical properties relative to electrostatic lens focusing, such that limiting the working distance also adversely affects the overall optical quality of the focused electron beam.

[0030] In the present disclosure, the term "working distance" can refer to the distance between the objective lens and the focus position and / or the distance between the objective lens and the sample surface on which the electron beam is focused. However, in various examples, the sample surface may not be precisely located at the focus position. Additionally, even when the objective lens is not positioned adjacent to the sample, it may be desirable to characterize the optical properties of the objective lens in terms of the working distance. Thus, in the present disclosure, the term "focus working distance" generally refers to the distance between the objective lens and the focus position, while the term "sample working distance" generally refers to the distance between the objective lens and the sample during the operational use of the objective lens as described herein.

[0031] Additionally, as used herein, the term "achievable operating working distance" refers to the focus working distance and / or the sample working distance that can be achieved and / or used during the operational use of the objective lens as described herein. For example, while the focus working distance can generally be described as representing the distance that separates the objective lens from the target focus position, there may be a limited range of focus working distances at which the objective lens can operate to produce the desired charged particle beam characteristics. Thus, the term "achievable operating working distance" can be understood to represent the working distance that can be achieved and / or used when the objective lens focuses the charged particle beam to the focus position and / or to a sample having the desired and / or expected properties (e.g., impact energy at the sample, characteristic beam diameter, axial electric field strength, etc.) as discussed herein.

[0032] The electrostatic field associated with the booster tube can protrude beyond the downstream end of the objective lens and into the region occupied by the sample probe. In such examples, the sample probe can interact with this electrostatic field to introduce perturbations and / or asymmetries in the field, which can adversely affect the beam focusing characteristics of the objective lens.

[0033] Some examples of objective lenses include shielding electrodes to at least partially shield the sample probe from the electrostatic field generated by the objective lens. For example, such shielding electrodes can limit the magnitude of the electrostatic field extending downstream of the electrostatic lens. However, by restricting the extent of the electrostatic field downstream of the objective lens, such shielding electrodes can undesirably limit the maximum achievable operating working distance of the objective lens. For example, such shielding electrodes can operate to concentrate the electrostatic field in the region of the shielding electrode, thereby creating a strong electrostatic lens effect in the region of the shielding electrode. Thus, generating an electron beam with low impact energy using an SEM can introduce various practical constraints, which in turn can require corresponding compromises when configuring the probe system.

[0034] In contrast, a CPM system according to the present disclosure can include an electrostatic lens and / or a magnetic objective lens that includes a plurality of electrodes that cooperate to limit the protrusion of the electrostatic field downstream of the objective lens. Such an objective lens can also operate to enhance the achievable operating working distance of the lens, such as by increasing the focusing working distance of the lens. In particular, and as discussed in more detail below, such an objective lens can include a shielding electrode combined with a manipulation electrode that operates to shift the principal object plane of the objective lens in the downstream direction, thereby increasing the focusing working distance without significantly degrading the beam focusing characteristics.

[0035] Figure 1 is a schematic diagram of an example of a CPM system 100 according to the present disclosure. The CPM system 100 can include a charged particle source 120, a sample holder 110 configured to hold a sample 112, and a beam guiding system 130. The charged particle source 120 can generate and / or emit a charged particle beam 122 along the optical axis 102 toward the sample 112, while the beam guiding system 130 can shape, modulate, focus, and / or direct the charged particle beam 122 to the sample 112.

[0036] The CPM system 100 can represent an example of any of a variety of CPM systems. In particular, the present disclosure generally relates to examples in which the CPM system 100 includes and / or is an SEM system, where the charged particle beam 122 is an electron beam 122 that is guided and focused onto the sample 112 by the beam guiding system 130. In such examples, the (focused) electron beam 122 can interact with the sample 112 in such a way that various types of stimulated radiation are emitted from the sample 112, including (for example) secondary electrons, backscattered electrons, X-rays, and / or optical radiation (cathodoluminescence). In an example where the charged particle beam 122 is an electron beam 122, the charged particle source 120 can also be referred to as an electron source and / or an electron emitter.

[0037] While the present disclosure generally relates to examples where the CPM system 100 is an SEM system, this is not required for all examples, and the systems and devices disclosed herein can also be used in combination with any suitable CPM configuration within the scope of the present disclosure. Examples of such CPMs include transmission electron microscopes (TEMs), scanning transmission electron microscopes (STEMs), focused ion beam (FIB) systems, and the like. For example, the systems and devices disclosed herein can also be used in combination with dual-beam CPM systems, such as systems that include an SEM system and an FIB system to direct multiple charged particle beams to a sample that is tilted relative to one or more of the charged particle beams.

[0038] The beam guiding system 130 can include any one of a variety of components and / or elements for operating the charged particle beam 122. For example, and as Figure 1 shown, the beam guiding system 130 can include an aperture 132 configured to limit the angular range of the charged particle beam 122, a condenser lens 134 configured to direct the charged particle beam 122 toward the sample 112, and / or one or more scan coils 136 configured to deflect the charged particle beam 122. In various examples, the beam guiding system 130 can additionally or alternatively include, in any suitable combination, an illuminator, an objective lens, a projection lens, a condenser lens, an electrostatic / magnetic lens, a deflector (e.g., a scan coil), a corrector (such as an astigmatism correction device), and the like.

[0039] The beam guiding system 130 can also include an energy booster 138 configured to energize the charged particle beam 122 as the charged particle beam 122 passes through the energy booster 138. In particular, the energy booster 138 can be maintained at an energy booster voltage such that the energy booster generates an associated electrostatic field that energizes the charged particle beam 122 within the energy booster 138. As a more specific example, the charged particle beam 122 can be an electron beam, and the energy booster 138 can be maintained at a positive voltage (e.g., approximately 8000 V) to accelerate the electron beam within the energy booster 138.

[0040] Upon exiting the energy booster 138, the electrostatic field generated by the energy booster and extending downstream of the energy booster can decelerate the charged particle beam 122. In this way, the energy booster 138 can generate a charged particle beam 122 having a sufficiently small impact energy downstream of the energy booster 138 to avoid damaging sensitive components of the sample 112, while maintaining the charged particle beam 122 at a sufficiently high energy within the beam guiding system 130 to avoid dispersion due to Coulomb interactions and / or charging effects. As used herein, the energy booster 138 can additionally or alternatively be referred to as an acceleration tube 138. Additional examples of energy boosters that can be used in combination with the systems and devices of the present disclosure are disclosed in U.S. Patent No. 9,443,692, the entire disclosure of which is incorporated herein by reference.

[0041] In operation, the impact energy of the charged particle beam 122 can be selected and / or varied via a corresponding change in the source energy of the charged particle beam 122 emitted by the charged particle source 120. In particular, the impact energy of the charged particle beam 122 can be equal to the difference between the source energy of the charged particle beam 122 at the charged particle source 120 and the bias voltage applied to the sample 112. However, when performing EFA, it may be desirable to hold the sample 112 at electrical ground to avoid damaging the sample 112 and / or otherwise interfering with the EFA analysis. Thus, in such examples, the impact energy of the charged particle beam 122 can be primarily and / or exclusively determined by and / or equal to the source energy of the charged particle beam 122 emitted by the charged particle source 120. Since the electrostatic field generated by the beam booster 138 is a conservative field, the net effect of the beam booster 138 on the impact energy (e.g., relative to the source energy) can be negligible.

[0042] As used herein, terms such as "upstream" and "downstream" are intended to refer to directions relative to the propagation of the charged particle beam 122. For example, and as Figure 1 shown, various components, features, etc. of the CPM system 100 can be described with reference to the upstream direction 104 and / or the downstream direction 106. The upstream direction 104 generally points towards the charged particle source 120 and / or away from the sample holder 110, while the downstream direction 106 generally points towards the sample holder 110 and / or away from the charged particle source 120.

[0043] As Figure 1 shown, the beam guiding system 130 also includes an objective lens 150 that operates to direct (e.g., condense and / or focus) the charged particle beam 122 to a focus position 124 (e.g., a position on or near the sample 112). The objective lens 150 can operate to focus the charged particle beam 122 by generating one or more electrostatic and / or magnetic fields that deflect the rays of the charged particle beam 122 towards a common focus position (e.g., the focus position 124). In particular, the objective lens 150 can be configured to generate a lens electrostatic field to at least partially direct and / or focus the charged particle beam 122 to the focus position 124.

[0044] In various examples, the objective lens 150 is also configured to generate a lens magnetic field to at least partially direct and / or focus the charged particle beam 122 to a focusing position 124. In particular, the present disclosure generally relates to examples of performing focusing using an appropriate combination of independently controlled electrostatic and magnetic fields. Such a configuration may be preferred, for example, because magnetic focusing can provide enhanced optical properties (e.g., smaller aberrations) for focusing the charged particle beam 122 relative to pure electrostatic focusing. Thus, while the present disclosure describes a lens electrostatic field in the context of focusing the charged particle beam 122, such a description does not exclude the presence and / or use of an additional lens magnetic field generated by the objective lens 150 operative to focus the charged particle beam 122. Thus, in the present disclosure, the objective lens 150 may additionally or alternatively be referred to as a compound lens 150, a compound objective lens 150, a compound electrostatic and magnetic lens 150, and / or a compound electrostatic and magnetic objective lens 150. However, this is not required, and the objective lens 150 may be a pure electrostatic lens and is also within the scope of the present disclosure.

[0045] The focusing position 124 may include, may be, and / or correspond to any location (e.g., a point, a region, a line, a plane, a volume, etc.) where the charged particle beam is sufficiently focused on the sample 112 and / or another component of the CPM system 100 described herein. For example, the focusing position 124 may include and / or may be a focal point and / or a focal plane associated with the objective lens 150. Thus, as used herein, the focusing position 124 may additionally or alternatively be referred to as a focal point 124 and / or a focal plane 124. In examples where the focusing position 124 includes at least a portion of a focal plane, it should be understood that such a focal plane is not necessarily a perfect plane. For example, the focal plane may be affected by field curvature associated with the objective lens 150. In some examples, the focusing position 124 may additionally or alternatively correspond to a position (e.g., a position along the optical axis 102) where the charged particle beam 122 exhibits a minimum diameter and / or a minimum degree of optical aberration.

[0046] As Figure 1 shown, the objective lens 150 may include a lens body 152 that circumferentially extends around a lens central axis 151 of the objective lens 150. The pole piece 152 may form at least a portion of the outer surface of the objective lens 150. In some examples, the lens body 152 may include and / or may be a pole piece configured to shape and / or direct a magnetic field generated by the objective lens 150 to at least partially focus the charged particle beam 122 to the focusing position 124. In such examples, the lens body 152 may also be referred to as the pole piece 152. In some such examples, and as Figure 1 shown, the pole piece 152 is a first pole piece 152, and the objective lens 150 and / or the lens body additionally includes a second pole piece 156 that is radially positioned inside the first pole piece 152, which in turn may be associated with a second magnetic field generated by the objective lens 150.

[0047] The CPM system 100 may include one or more electron detectors configured to detect electrons emitted from the sample 112. For example, as Figure 1 shown, the CPM system 100 may include a backscattered electron detector 126 configured to detect backscattered electrons and / or a secondary electron detector 128 configured to detect secondary electrons emitted from the sample 112.

[0048] As Figure 1 shown, each of the backscattered electron detector 126 and the secondary electron detector 128 may be positioned within and / or supported by the objective lens 150, such as adjacent to and / or supported by the booster tube 138. In particular, an electrostatic field generated by applying a positive booster tube voltage to the booster tube 138 may operate to accelerate free electrons toward and / or to the backscattered electron detector 126 and / or the secondary electron detector 128.

[0049] Although Figure 1 each electron detector is shown as being positioned within the objective lens 150, this is not required, and it should be understood that the CPM system 100 may additionally or alternatively include any other suitable charged particle detector and / or electron detector. For example, the CPM system 100 may include one or more electron detectors positioned outside the objective lens 150.

[0050] Measurements characterizing the electrons incident on the backscattered electron detector 126 and / or the secondary electron detector 128 (e.g., characterizing the intensity and / or energy of such detected electrons) may provide an indication of various physical properties of the sample 112, such as the geometric structure of the sample 112 and / or the chemical composition of the sample 112 at the location where the electron beam 122 is incident on the sample 112 (e.g., at the focus position 124). Such measurements can thus be used to form an image (e.g., a graphical representation) of the sample at the focus position. Thus, the CPM system 100 may characterize the spatial resolution of the sample 112 based at least in part on the minimum size (e.g., minimum diameter) of the electron beam 122 in the plane corresponding to the location where the sample 112 is located.

[0051] Accordingly, scanning the electron beam 122 across the surface of the sample 112 can generate an image and / or other representation of the sample 112 in the scanned region. Such scanning can be accomplished in any suitable manner. For example, the scanning coil 136 can be operated to deflect the electron beam 122 to scan the charged particle beam 122 across the sample 112 and / or move the focus position 124 relative to the sample 112. Additionally or alternatively, the sample holder 110 can be configured to rotate and / or translate the sample 112 in one or more dimensions to move the sample 112 relative to the focus position 124. This translation of the sample 112 and / or scanning of the electron beam 122 can thus allow a selected portion of the sample 112 to be irradiated / imaged / examined by the electron beam 122 traveling along the optical axis 102.

[0052] As Figure 1 shown, the booster tube 138 can extend at least partially within the objective lens 150. As described above, applying a booster tube voltage to the booster tube 138 can generate an electrostatic field that can project from the objective lens 150 and into the test region 111 downstream of the objective lens 150. The electrostatic field generated by the booster tube 138 can represent at least a portion of the lens electrostatic field.

[0053] In various examples, it may be desirable to limit the magnitude of the lens electrostatic field downstream of the objective lens 150 and / or within the test region 111. For example, and as Figure 1 shown, the CPM system 100 can also include one or more sample probes 114 that are configured to be positioned adjacent corresponding sample test locations 113 of the sample 112. The sample probes 114 and / or the sample test locations 113 can be at least partially positioned within the test region 111. As used herein, the sample probes 114 can additionally or alternatively be referred to as nano-probes 114.

[0054] As Figure 1 shown, each sample probe 114 can include a probe tip 116 and a probe beam 115, the probe tip being configured to be positioned adjacent a corresponding sample test location 113 of the sample 112, the probe beam extending away from the probe tip 116. In Figure 1 an example, each probe tip 116 is configured to directly contact the corresponding sample test location 113, such as to establish electrical contact with the sample test location 113. In other examples, each sample probe 114 and / or its probe tip 116 can be configured as a non-contact probe (e.g., an optical probe configured to optically couple to the sample test location 113) that is configured to approach the corresponding sample test location 113 without directly contacting the sample test location 113.

[0055] Each sample probe 114 can be moved relative to the sample 112 in any suitable manner (e.g., translation and / or rotation). For example, as Figure 1 shown, the probe beam 115 of each sample probe 114 can be supported by a corresponding probe manipulator 117 that is configured to move the sample probe 114 relative to the sample 112 to position the sample probe 114 adjacent to the sample test location 113. Additionally or alternatively, the sample holder 110 can include and / or can be a motion platform that is configured to move the sample 112 relative to the sample probe 114 (e.g., translation and / or rotation).

[0056] In the absence of such sample probes 114, the lens electrostatic field extending within the test region 111 can remain sufficiently symmetric about the optical axis to allow the lens electrostatic field to focus the charged particle beam 122 in a controlled and precise manner. However, in an example where a sample probe 114 extends within the test region 111, the sample probe 114 can interact with the lens electrostatic field in a manner that creates an asymmetry in the lens electrostatic field and / or otherwise perturbs the lens electrostatic field. Such perturbations can adversely affect the focusing characteristics of the lens electrostatic field within the test region 111, which can in turn result in an undesired spot size of the charged particle beam 122 at the focusing position 124. Thus, in such examples, it may be desirable to limit the magnitude of the lens electrostatic field within the test region 111 to maintain and / or enhance the focusing characteristics of the lens electrostatic field.

[0057] Thus, and as Figure 1 shown, the objective lens 150 includes a shield electrode 160 that is configured to at least partially shield the test region 111 from the lens electrostatic field generated within the objective lens 150 (e.g., by the booster tube 138). In particular, the shield electrode 160 can be configured to at least partially shield the sample probe 114 from the lens electrostatic field. The shield electrode 160 can be disposed within the downstream end region 108 of the objective lens 150 and / or the lens body 152. In particular, and as Figure 1 shown, the shield electrode can be positioned at or near the downstream end of the objective lens 150.

[0058] The shield electrode 160 can operate to limit the protrusion of the lens electrostatic field downstream of the objective lens 150 in any of a variety of ways. For example, the shield electrode 160 can be configured to be held at electrical ground to at least partially limit the protrusion of the lens electrostatic field into the test region 111. In such examples, grounding the shield electrode 160 can increase the magnitude of the lens electrostatic field at or near the shield electrode 160, thereby creating a strong focusing effect that operates to limit the available operating working distance of the objective lens 150.

[0059] As Figure 1As shown, the objective lens 150 additionally includes a steering electrode 166 positioned upstream of the shielding electrode 160. As discussed in more detail below, the steering electrode 166 can be operated to increase the focusing working distance of the objective lens 150 to at least partially counteract the effect of the shielding electrode 160 on the available operating working distance. In particular, the objective lens 150 can be configured such that applying a steering electrode voltage to the steering electrode 166 and / or varying the steering electrode voltage applied to the steering electrode 166 operates to control and / or vary the focusing working distance.

[0060] As Figure 1 shown, the CPM system 100 can also include a controller 180 that is programmed and / or otherwise configured to at least partially control the operation of the CPM system 100. For example, the controller 180 can at least partially control the operation of the charged particle source 120 to generate a charged particle beam 122 and / or can at least partially control the operation of at least a portion of the beam guidance system 130. Additionally or alternatively, the controller 180 can receive signals representative of electrons emitted from the surface of the sample 112 from the backscattered electron detector 126 and / or from the secondary electron detector 128, and the signals can be used to generate an image and / or other representation of the sample 112.

[0061] In some examples, the controller 180 can also at least partially control the operation of the objective lens 150, such as by selectively and dynamically controlling and / or varying the booster voltage and / or the steering electrode voltage. This can be accomplished by adjusting one or more electrical signals (e.g., voltages) delivered to the objective lens 150. For example, and as Figure 1 shown, the controller 180 can include a first voltage source 182 that is configured to apply a booster voltage to the booster 138. In particular, the first voltage source 182 can be configured to transmit a first electrical signal 184 to the booster 138 that applies the booster voltage to the booster 138.

[0062] Additionally or alternatively, the controller 180 can include a second voltage source 186 that is configured to apply a steering electrode voltage to the steering electrode 166. In particular, the second voltage source 186 can be configured to transmit a second electrical signal 188 to the steering electrode 166 that applies the steering electrode voltage to the steering electrode 166.

[0063] In some examples, the controller 180 may be further configured to control and / or regulate the shielding electrode voltage applied to and / or maintained at the shielding electrode 160. For example, the controller 180 may include a third voltage source 190 configured to transmit a third electrical signal 192 to the shielding electrode 160. In some examples, the third voltage source 190 and / or the third electrical signal 192 may include electrical ground and / or be electrical ground. However, this is not required in all examples, and the third voltage source 190 may hold the shielding electrode 160 at any suitable voltage, which is also within the scope of the present disclosure.

[0064] As described herein, the controller 180 may be programmed and / or configured to control and / or vary the first electrical signal 184, the second electrical signal 188, and / or the third electrical signal 192 to at least partially control the operation of the objective lens 150, such as adjusting the focusing working distance and / or other focusing characteristics of the objective lens 150.

[0065] As Figure 1 shown, the controller 180 may include a user interface 194 for receiving input from a human user and / or for recording and / or displaying information. In particular, the user interface 194 may include one or more input devices 196 and / or one or more output devices 198. The one or more input devices 196 may include and / or may be any suitable device for receiving input from a human user to at least partially direct the operation of the CPM system 100, such as a keyboard, a mouse, a display, a touch screen, etc. The one or more output devices 198 may include and / or may be any suitable device for conveying information to a human user, such as a display, a touch screen, a physical storage drive, etc.

[0066] The controller 180 may include any one of various modules (e.g., hardware and / or software) for performing these and other functions. In some examples, the controller 180 is a single device including each of the components described herein. In other examples, the controller 180 may refer to and / or encompass a collection of components that may be at least partially spatially separated. The controller 180 may be connected to any other suitable components of the 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 may be physical signal conduits, such as wires, electrical buses, optical fibers, etc.

[0067] Figure 2 Aspects of the objective lens 250 positioned adjacent to the sample 212 and the plurality of sample probes 214 are shown. Figure 2 of the objective lens 250 are substantially similar to Figure 1 of the objective lens 150 and may be described as representing Figure 1An example of the objective lens 150. Thus, in Figures 1 to 2 the same reference numerals are used to label the same components. Specifically, unless otherwise stated, Figure 2 all of the illustrated components, whether labeled or unlabeled, may share any suitable features, characteristics, properties, etc. with the Figure 1 corresponding components. For Figure 2 those components labeled in Figure 1 , the components labeled with reference numerals of the form "2XX" are intended to correspond to the Figure 2 components labeled with reference numerals of the form "1XX" in Figure 1 . For example,

[0068] as Figure 2 shown, the shield electrode 260 and the steering electrode 266 are disposed within the downstream end region 208 of the lens body 252, where the steering electrode 266 is positioned upstream of the shield electrode 260. The booster tube 238 extends around the lens central axis 251 upstream of each of the shield electrode 260 and the steering electrode 266. In this way, each of the shield electrode 260 and the steering electrode 266 is operable to modulate the portion of the lens electrostatic field generated by the booster tube 238 and extending toward and / or into the test region 211.

[0069] As described above, the shield electrode 260 can be described as operating to at least partially shield the test region 211 and / or the sample probe 214 from the lens electrostatic field generated by the booster tube 238 and / or a portion thereof. Referring to Figure 2 , the operation of the steering electrode 266 can be characterized relative to the focusing working distance 218 of the objective lens 250 and / or the focal length 244 of the objective lens 250. In particular, as Figure 2 shown, when the objective lens 250 operates to focus the charged particle beam to the focusing position 224, the focusing working distance 218 can be described as representing the distance between the most downstream portion of the objective lens 250 (e.g., the shield electrode 260) and the focusing position 224.

[0070] As Figure 2 shown, the operation of the objective lens 250 can additionally or alternatively be characterized with reference to the sample working distance 219. In particular, the sample working distance 219 can be described as representing the distance between the most downstream portion of the objective lens 250 (e.g., the shield electrode 260) and the portion (e.g., the surface) of the sample 212 to which the objective lens 250 directs the charged particle beam. In Figure 2In an example, the surface of sample 212 is positioned at the focusing position 224 such that the focusing working distance 218 is equal to the sample working distance 219. However, this is not required for all examples, and the focusing working distance 218 can be different from the sample working distance 219 (such as when the sample 212 is not positioned at the focusing position 224) and is also within the scope of the present disclosure. The focusing working distance 218, the sample working distance 219, and / or the focal length 244 can be measured along a direction parallel to the optical axis 202 and / or the lens central axis 251.

[0071] The focusing working distance 218 characterizing the operation of the objective lens 250 can be related to the focal length 244 of the objective lens 250, and the focal length of the objective lens in turn corresponds to the distance between the focusing position 224 and the principal object plane 242 of the objective lens 250. As Figure 2 shown, the principal object plane 242 can be described as a plane extending perpendicular to the optical axis 202 and intersecting the optical axis 202. As described herein, the position where the principal object plane 242 intersects the optical axis 202 can vary based on the operating characteristics of the objective lens 250.

[0072] In various examples, the steering electrode 266 operates to adjust the position of the principal object plane 242 relative to the objective lens 250. For example, applying a steering electrode voltage that becomes increasingly positive to the steering electrode 266 can operate to adjust and / or shift the principal object plane 242 in the downstream direction 206. This can be performed while maintaining the focal length 244 at a constant value or at least a substantially constant value. Thus, shifting the principal object plane 242 in the downstream direction can also operate to shift the focusing position 224 in the downstream direction, thereby increasing the focusing working distance 218.

[0073] In some examples, the steering electrode 266 additionally or alternatively can operate to limit the impact energy of the charged particle beam at the sample 212. In particular, similar to applying a positive booster voltage to the booster tube 238, applying a positive steering electrode voltage to the steering electrode 266 can generate an electrostatic field that operates to decelerate the electrons propagating downstream of the steering electrode 266.

[0074] The shielding electrode 260 and the steering electrode 266 can each have any suitable form and / or structure. For example, and as Figure 2 shown, the shielding electrode 260 can include a shielding electrode aperture 262 through which the lens central axis 251 and / or the optical axis 202 extends. Similarly, the steering electrode 266 can include a steering electrode aperture 268 through which the lens central axis 251 and / or the optical axis 202 extends.

[0075] Either or both of the shielding electrode 260 and / or the steering electrode 266 may extend circumferentially about the lens central axis 251 (e.g., extend completely circumferentially about the lens central axis 251) and / or may be circumferentially symmetric about the lens central axis 251. In particular, configuring the shielding electrode 260 and / or the steering electrode 266 to be circumferentially symmetric about the lens central axis 251 may facilitate generating a lens electrostatic field that is similarly at least substantially circumferentially symmetric about the lens central axis 251.

[0076] In various examples, the shielding electrode 260 is shaped to correspond to the shape and / or configuration of the sample probe 214. For example, and as Figure 2 shown, the probe tip 216 of each sample probe 214 may be angled relative to the probe beam 215 toward the sample holder 210 and / or the sample 212. Thus, while the presence of the probe beam 215 may limit the objective lens 250 from being positioned arbitrarily close to the sample 212, the deflection of the probe tip 216 toward the sample 212 may create a region where the central portion of the objective lens 250 may be positioned closer to the sample 212.

[0077] Accordingly, the central portion of the shielding electrode 260 may project in the downstream direction 206 to position the shielding electrode 260 closer to the sample 212 in the region adjacent to the probe tip 216. As a more specific example, and as Figure 2 shown, the shielding electrode 260 may include: a shielding electrode central region 261 that includes and / or defines a shielding electrode aperture 262; and a shielding electrode peripheral region 263 that is radially external to the shielding electrode central region 261. The shielding electrode central region 261 may extend away from the shielding electrode peripheral region 263 along the downstream direction 206. In particular, in this example, the shielding electrode central region 261 extends along the downstream direction 206 such that the shielding electrode central region 261 is at least partially frustoconical in shape. Additionally, in this example, the shielding electrode central region 261 extends in the downstream direction 206 beyond the lens body 252. In this way, the shielding electrode central region 261 may extend closer to the sample 212 than the shielding electrode peripheral region 263, thereby reducing the focusing working distance 218 relative to a configuration where the shielding electrode 260 is flat and / or planar.

[0078] In various examples, the shielding electrode central region 261 may be angled relative to the shielding electrode peripheral region 263 by a degree similar to the degree by which each probe tip 216 is angled relative to the corresponding probe beam 215. As Figure 2 shown, such a configuration may allow the shielding electrode central region 261 to be spaced from the probe tip 216 by a distance that is substantially similar to the distance by which the shielding electrode peripheral region 263 is spaced from the probe beam 215.

[0079] The manipulation electrode 266 may be similar in shape and / or form to the shielding electrode 260. For example, and as Figure 2 shown, the manipulation electrode 266 may include: a manipulation electrode central region 267 that includes and / or defines a manipulation electrode orifice 268; and a manipulation electrode peripheral region 269 that is radially external to the manipulation electrode central region 267. The manipulation electrode central region 267 may extend away from the manipulation electrode peripheral region 269 along the downstream direction 206. In particular, in Figure 2 the example, the manipulation electrode central region 267 extends along the downstream direction 206 such that the manipulation electrode central region 267 is at least partially frustoconical in shape. In this example, the manipulation electrode central region 267 extends in the downstream direction 206 such that a portion of the manipulation electrode central region 267 is received within the shielding electrode central region 261.

[0080] The shielding electrode 260 and the manipulation electrode 266 may be supported by the objective lens 250 in any of a variety of ways. For example, and as Figure 2 shown, the shielding electrode 260 may be directly coupled to and / or supported by the lens body 252. In particular, in this example, the shielding electrode 260 is coupled to the lens body 252 at the shielding electrode peripheral region 263. In some examples, the shielding electrode 260 may be electrically coupled to the lens body 252.

[0081] In Figure 2 the example, the manipulation electrode 266 is coupled to the shielding electrode 260 via the manipulation electrode peripheral region 269. In particular, in this example, the objective lens 250 includes an electrode support 272 that couples the shielding electrode 260 and the manipulation electrode 266 to each other, such as by supporting the manipulation electrode 266 relative to the shielding electrode 260. In this example, the electrode support 272 is an annular structure that extends between the shielding electrode peripheral region 263 and the manipulation electrode peripheral region 269. In other examples, the electrode support 272 may include a plurality of spaced-apart members that are circumferentially spaced about the lens central axis 251.

[0082] In this way, in Figure 2 the example, the manipulation electrode 266 may be described as being at least partially supported by the shielding electrode 260. However, this is not required in all examples, and it is also within the scope of the present disclosure for the manipulation electrode 266 to be supported by any other part of the objective lens 250. For example, the manipulation electrode 266 may be at least partially and / or exclusively supported by the lens body 252.

[0083] The manipulation electrode 266 can be electrically isolated from the shield electrode 260 and / or the lens body 252. In this way, the manipulation electrode 266 can be maintained at a manipulation electrode voltage different from the voltage (e.g., electrical ground) maintained by the shield electrode 260. In particular, in some examples, the electrode support 272 can include an electrically insulating material that electrically isolates the manipulation electrode 266 from the shield electrode 260.

[0084] As described above, using the manipulation electrode 266 in combination with the shield electrode 260 can allow adjustment of the maximum achievable operating working distance (e.g., by controlling and / or adjusting the focusing working distance 218), while limiting the protrusion of the lens electrostatic field downstream of the shield electrode 260. One or more dimensions of the shield electrode 260 and / or the manipulation electrode 266 can be selected and / or configured at least in part based on such functionality. For example, and as Figure 2 shown, the shield electrode aperture 262 can be characterized by a shield electrode aperture diameter 264. Generally speaking, configuring the shield electrode 260 to have an increasingly smaller shield electrode aperture diameter can more effectively limit the protrusion of the lens electrostatic field downstream of the shield electrode 260, but can also correspondingly increase the lens effect that tends to limit the achievable operating working distance. Therefore, the shield electrode aperture diameter 264 can be selected and / or configured to balance the consideration of limiting the protrusion of the lens electrostatic field while maintaining the achievable value of the focusing working distance 218 at a sufficiently high value.

[0085] As Figure 2 shown, the manipulation electrode aperture 268 can similarly be characterized by a manipulation electrode aperture diameter 270. In Figure 2 the example, the manipulation electrode aperture diameter 270 is greater than the shield electrode aperture diameter 264. In this way, the shield electrode 260 can also operate to shield the test area 211 from the electrostatic field generated by the manipulation electrode 266. In contrast, in examples where the manipulation electrode aperture diameter 270 is equal to or less than the shield electrode aperture diameter 264, a portion of the electrostatic field generated by the manipulation electrode 266 may undesirably protrude into the test area 211. However, not all examples require Figure 2 the configuration shown, and it is also within the scope of the present disclosure that the manipulation electrode aperture diameter 270 can be equal to or less than the shield electrode aperture diameter 264.

[0086] Figure 3 is a cross-sectional view of another example of the objective lens 350. The objective lens 350 can be described as Figure 1 an example of the objective lens 150 and / or Figure 1 a component of the CPM system 100. Therefore, the same reference numerals are used to label the same components in Figure 3 and Figures 1 to 2 Specifically, unless otherwise indicated,Figure 3 All of the shown components, whether labeled or unlabeled, may share any suitable features, characteristics, properties, etc. with the corresponding components of any one of Figures 1 to 2 . For Figure 3 the components labeled in Figure 1 , the components labeled with reference numerals of the form "3XX" are intended to correspond to the components labeled with reference numerals of the form "1XX" in Figure 2 and / or the components labeled with reference numerals of the form "2XX" in

[0087] Similar to Figure 2 the objective lens 250 of Figure 3 , the objective lens 350 of Figure 3 includes a shield electrode 360 coupled to a lens body 352, wherein a shield electrode center region 361 extends away from the lens body 352 in a downstream direction 306. The objective lens 350 additionally includes a steering electrode 366, which is supported relative to the shield electrode 360 by an annular electrode support 372. The downstream end portion of the booster tube 338 is shown in

[0088] Figures 4A to 4D It shows the influence of the shield electrode and the steering electrode pair on the focusing characteristics of the objective lens according to the present disclosure. In particular, Figures 4A to 4D shows that in the presence of multiple sample probes (e.g., Figure 1 the sample probe 114 of Figure 2 or Figure 1 the objective lens 150 of Figure 2 the objective lens 250 of Figure 3 the objective lens 350 of Figures 4A to 4D ), the modeled beam profiles of the charged particle beams 422a to 422d at the focusing position downstream of the objective lens (e.g., Figure 1 the focusing position 124 of Figure 2 and / or Figures 4A to 4D can be described as representing the characteristics of the charged particle beam 122 of the CPM system 100 of Figure 1 under various operating conditions. Figures 4A to 4D Each of Figure 1 the booster tube 138 of Figure 2 the booster tube 238 of Figure 3 the booster tube 338 of

[0089] Figures 4A to 4B corresponds to an example where the booster tube voltage applied to the booster tube (e.g., Figures 4C to 4DRepresents a modeled beam profile with a manipulation electrode voltage applied to the manipulation electrode. Additionally, Figure 4A and Figure 4C represent configurations in which the charged particle beams 422a / 422c are incident on the focal plane with an impact energy of 200 eV, while Figure 4B and Figure 4D represent configurations in which the charged particle beams 422b / 422d are incident on the focal plane with an impact energy of 80 eV.

[0090] As a representative measurement of the focusing characteristics of the objective lens configuration corresponding to each of Figures 4A to 4D , Figures 4A to 4D also shown are the characteristic beam diameters 423a to 423d associated with the modeled charged particle beams 422a to 422d. In particular, each of the characteristic beam diameters 423a to 423d corresponds to the diameter of a circle or ring oriented perpendicular to the lens central axis and / or perpendicular to the optical axis, the circle or ring containing 50% of the charged particles of the charged particle beams 422a to 422b at the focal position.

[0091] In the Figure 4A example, the characteristic beam diameter 423a corresponding to an impact energy of 200 eV is 61 nm, while in the Figure 4B example, the characteristic beam diameter 423b corresponding to an impact energy of 80 eV is 114 nm. Thus, comparing Figures 4A to 4B , it can be seen that in the absence of a manipulation electrode voltage, reducing the impact energy from 200 eV to 80 eV (e.g., by reducing the energy of the electrons emitted by an electron emitter such as Figure 1 charged particle source 120) corresponds to an increase in the characteristic beam diameter 423b. This increase in the characteristic beam diameter 423b can be caused by an increase in the protrusion into the test area due to the increased energy boost tube voltage in the lens electrostatic field. This increase in the characteristic beam diameter 423b can result in a corresponding reduction in the image quality of the sample image produced by the associated CPM system.

[0092] In contrast, in the Figure 4C example, the characteristic beam diameter 423b corresponding to an impact energy of 200 eV with a manipulation voltage applied to the manipulation electrode is 12 nm, while in the Figure 4D example, the characteristic beam diameter 423d corresponding to an impact energy of 80 eV with a manipulation voltage applied to the manipulation electrode is 38 nm. In particular, Figures 4C to 4D the example can be described as corresponding to a manipulation voltage in the range of 1000 V to 2000 V. Comparing Figure 4A and Figure 4C , and comparing Figure 4B and Figure 4D, it can be seen that for a given impact energy value, applying a manipulation electrode voltage to the manipulation electrode results in a significantly smaller characteristic beam diameter, which in turn can produce a clearer image of the sample when the charged particle beam 422c / 422d is used to image the sample. In particular, Figure 4D The modeling results show that the use of the manipulation electrode enables focusing the charged particle beam 422d with an acceptably small characteristic beam diameter 423d and at a desired low impact energy that would otherwise be associated with an undesired large characteristic beam diameter.

[0093] Figures 5A to 5F Represents additional examples of modeling parameters associated with the objective lens according to the present disclosure. Similar to Figures 4A to 4D , Figures 5A to 5F each of which can be described as representing the characteristics of a charged particle beam associated with (e.g., generated and / or focused by) any one of the CPM systems and / or objective lenses in Figures 1 to 3 .

[0094] Figures 5A to 5F each of which represents the characteristic beam diameters 523a to 523f (in nm) associated with the charged particle beam focused by the objective lens according to the present disclosure. Specifically, Figures 5A to 5F each of which represents the relationship between the impact energy (LE) of the charged particle beam at the focus position and the characteristic beam diameter associated with each impact energy in a given operating configuration of the CPM system. In this way, Figures 5A to 5F shows the trade-off between the prominent electrostatic field (represented as the axial electric field strength E z ) at the sample position, the achievable minimum impact energy, and the characteristic beam diameter that can be obtained. For example, Figures 5A to 5F each of which can represent the manner in which the characteristic beam diameters 523a to 523f vary as the impact energy changes at a constant value of the booster tube voltage and a constant focusing working distance. Specifically, in Figures 5A to 5F each of which, the characteristic beam diameters 523a to 523f correspond to the charged particle beam at the focus position characterized by a focusing working distance of 2.5 mm. In Figures 5A to 5F each of which, the change in the impact energy can be achieved via a corresponding change in the energy of the electrons emitted by an electron emitter (e.g., Figure 1 the charged particle source 120).

[0095] In Figures 5A to 5F each of which is also represented is the axial electric field strength E of the lens electrostatic field associated with the operating configuration represented in the figure z. In these examples, the axial electric field strength represents the magnitude of the electrostatic lens field measured at the focusing position and in a direction parallel to the optical axis. In this way, the axial electric field strength can be understood as a measure representing the extent to which the electrostatic lens field protrudes into the test region and / or the focusing position.

[0096] Figures 5A to 5C Each of which corresponds to a configuration without using the steering electrode, while Figures 5D to 5F Each of which corresponds to a configuration in which the steering electrode voltage is applied to the steering electrode.

[0097] Figures 5A to 5C Each of which can be described as representing the dependence of the characteristic beam diameters 523a to 523c on the impact energy and / or beam current at a common accelerating tube voltage and at different respective aperture diameters D A . For example, Figures 5A to 5C Each of which can represent Figure 2 The corresponding values of the shield electrode aperture 264 of (without using and / or in the absence of the steering electrode 266), where Figure 5A represents D A = 5 mm shield electrode aperture diameter, Figure 5B represents D A = 4.5 mm shield electrode aperture diameter, and Figure 5C represents D A = 4 mm shield electrode aperture diameter.

[0098] Comparing Figures 5A to 5C , it can be seen that reducing the shield electrode aperture (e.g., from 5 mm to 4 mm) has the effect of desirably reducing the axial electric field strength at the focusing position. However, this reduction in the shield electrode aperture also undesirably results in an increase in the characteristic beam diameters 523a to 523f associated with a given impact energy value. Although the shield electrode aperture diameter and / or beam current can be adjusted to balance the axial electric field strength and the characteristic beam diameter, it may not be possible to achieve both a desirably small axial electric field strength and a desirably small characteristic beam diameter at a desired small impact energy value. For example, comparing Figures 5A to 5C , it can be seen that the combination of these operating parameters does not produce a characteristic beam diameter of less than about 5 nm at an impact energy of less than 100 eV and an axial electric field strength of less than 175 eV, which is desirable for high-resolution imaging during EFA.

[0099] In contrast, Figures 5D to 5F represents the correspondence between the characteristic beam diameters 523d to 523f at a common accelerating tube voltage and a common value of the shield electrode voltage diameter, but with different respective values of the steering electrode voltage applied to the steering electrode. Specifically, Figure 5D represents the configuration with a steering electrode voltage of 2000 V,Figure 5E represents a configuration with a manipulation electrode voltage of 1500 V, Figure 5F represents a configuration with a manipulation electrode voltage of 1000 V. Figures 5D to 5F Each of Figures 5D to 5F represents a configuration with an intensifying tube voltage of 8000 V.

[0100] Similar to Figures 5A to 5C the effect of reducing the shield electrode orifice in Figures 5A to 5C , it can be seen in Figures 5D to 5F that reducing the manipulation electrode voltage (e.g., from 2000 V to 1000 V) has the effect of desirably reducing the axial electric field strength at the focusing position. Although such a reduction in the manipulation electrode voltage results in an increase in the characteristic beam diameter 523d to 523f associated with a given impact energy value, the use of the manipulation electrode enables the system to achieve a desired combination of these parameters. Figures 5D to 5F For example, different from the example of Figures 5A to 5C , it can be seen (e.g., in Figure 5E ) that an impact energy of less than 100 eV can be achieved using a characteristic beam diameter 523e of less than 6 nm and using an axial electric field strength at the focusing position significantly less than that in the example of Figures 5A to 5C . Additionally, comparing Figure 5E with Figure 5D , it can be seen that by increasing the manipulation electrode voltage, a lower impact energy can be achieved at a given characteristic beam diameter (or a smaller characteristic beam diameter can be achieved at a given impact energy), at the cost of an increased axial electric field strength. Alternatively, comparing Figure 5E and Figure 5F , it can be seen that by reducing the manipulation electrode voltage, a smaller axial electric field strength can be achieved, at the cost of an increased characteristic beam diameter at a given impact energy (or an increased impact energy at a given characteristic beam diameter).

[0101] For example, Figures 5A to 5C different from the example of Figures 5A to 5C , it can be seen (e.g., in Figure 5E ) that an impact energy of less than 100 eV can be achieved using a characteristic beam diameter 523e of less than 6 nm and using an axial electric field strength at the focusing position significantly less than that in the example of Figures 5A to 5C . Additionally, comparing Figure 5E with Figure 5D , it can be seen that by increasing the manipulation electrode voltage, a lower impact energy can be achieved at a given characteristic beam diameter (or a smaller characteristic beam diameter can be achieved at a given impact energy), at the cost of an increased axial electric field strength. Alternatively, comparing Figure 5E and Figure 5F , it can be seen that by reducing the manipulation electrode voltage, a smaller axial electric field strength can be achieved, at the cost of an increased characteristic beam diameter at a given impact energy (or an increased impact energy at a given characteristic beam diameter). Figure 5E Figure 5E Figures 5A to 5C Figures 5A to 5C Figure 5E with Figure 5D Figure 5D Figure 5E and Figure 5F Figure 5F

[0102] In practice, an optimal balance among the axial electric field strength, the characteristic beam diameter, and the impact energy can be achieved via appropriate variations in the manipulation electrode voltage and appropriate selections of the intensifying tube voltage, the beam current, and the shield electrode orifice. Comparing Figures 5D to 5F with Figures 5A to 5C , it can be seen that even at a constant value of the shield electrode orifice, variations in the manipulation electrode voltage can achieve a favorable combination of such parameters. Figures 5D to 5F with Figures 5A to 5C Figures 5A to 5C

[0103] Each of the operating parameters discussed herein can vary within any suitable value range. In practice, the specific value of any one of the operating parameters discussed herein can be selected and / or adjusted based on the requirements and / or constraints of a given operating configuration (e.g., to a value within any of the ranges disclosed herein).

[0104] As an example, the intensifier tube voltage applied to any intensifier tube disclosed herein (e.g., Figure 1 intensifier tube 138, Figure 2 intensifier tube 238, or Figure 3 intensifier tube 238) can be at least 5 kilovolts (kV), at least 7 kV, at least 10 kV, at most 12 kV, at most 8 kV, at most 6 kV, 5 kV to 8 kV, 7 kV to 12 kV, and / or 5 kV to 12 kV.

[0105] Additionally or alternatively, the manipulation electrode voltage applied to any manipulation electrode disclosed herein (e.g., Figure 1 manipulation electrode 166, Figure 2 manipulation electrode 266, or Figure 3 manipulation electrode 366) can be at least 500 V, at least 1000 V, at least 1500 V, at least 2000 V, at most 2500 V, at most 1700 V, at most 1200 V, at most 700 V, 500 V to 1200 V, 1000 V to 1700 V, 1500 V to 2500 V, 500 V to 1700 V, 1000 V to 2500 V, and / or 500 V to 2500 V.

[0106] Additionally or alternatively, any objective lens disclosed herein (e.g., Figure 1 objective lens 150, Figure 2 objective lens 250, or Figure 3 objective lens 350) can be configured to operate at a focusing working distance on the order of millimeters (e.g., Figure 2 working focal length 218). As a more specific example, the focusing working distance can be at least 1 millimeter (mm), at least 2 mm, at least 5 mm, at least 10 mm, at most 15 mm, at most 7 mm, at most 3 mm, at most 1.5 mm, 1 mm to 3 mm, 2 mm to 7 mm, 5 mm to 15 mm, 1 mm to 7 mm, 3 mm to 15 mm, and / or 1 mm to 15 mm.

[0107] Additionally or alternatively, any objective lens disclosed herein (e.g., Figure 1 objective lens 150, Figure 2 objective lens 250, or Figure 3 objective lens 350) can be configured to operate such that a charged particle beam (e.g., Figure 1 charged particle beam 122) is at a focusing position associated with the objective lens (e.g., Figure 2The impact energy at the focusing position 224) is at least 5 eV, at least 10 eV, at least 20 eV, at least 30 eV, at least 50 eV, at least 70 eV, at least 90 eV, at least 120 eV, at most 200 eV, at most 150 eV, at most 100 eV, at most 80 eV, at most 60 eV, at most 40 eV, at most 25 eV, at most 15 eV, at most 7 eV, 5 eV to 15 eV, 10 eV to 25 eV, 20 eV to 40 eV, 30 eV to 60 eV, 50 eV to 80 eV, 70 eV to 100 eV, 90 eV to 150 eV, 120 eV to 200 eV, 5 eV to 25 eV, 10 eV to 40 eV, 20 eV to 60 eV, 30 eV to 80 eV, 50 eV to 100 eV, 70 eV to 150 eV, 90 eV to 200 eV, 5 eV to 40 eV, 10 eV to 60 eV, 20 eV to 80 eV, 30 eV to 100 eV, 50 eV to 150 eV, 70 eV to 200 eV, 5 eV to 60 eV, 10 eV to 80 eV, 20 eV to 100 eV, 30 eV to 150 eV, 50 eV to 200 eV, 5 eV to 80 eV, 10 eV to 100 eV, 20 eV to 150 eV, 30 eV to 200 eV, 5 eV to 100 eV, 10 eV to 150 eV, 20 eV to 200 eV, 5 eV to 150 eV, 10 eV to 200 eV, and / or 5 eV to 200 eV.

[0108] Additionally or alternatively, any objective lens disclosed herein (e.g., Figure 1 objective lens 150, Figure 2 objective lens 250, or Figure 3 objective lens 350) may be configured to operate such that the axial electric field strength of the lens electrostatic field generated by the objective lens is at least 70 volts per millimeter (V / mm), at least 90 V / mm, at least 120 V / mm, at least 140 V / mm, at least 160 V / mm, at most 175 V / mm, at most 150 V / mm, at most 130 V / mm, at most 100 V / mm, at most 80 V / mm, 70 V / mm to 100 V / mm, 90 V / mm to 130 V / mm, 120 V / mm to 150 V / mm, 140 V / mm to 175 V / mm, 70 V / mm to 130 V / mm, 90 V / mm to 150 V / mm, 120 V / mm to 175 V / mm, 70 V / mm to 150 V / mm, 90 V / mm to 175 V / mm, and / or 70 V / mm to 175 V / mm.

[0109] Additionally or alternatively, any objective lens disclosed herein (e.g., Figure 1 objective lens 150, Figure 2 objective lens 250, orFigure 3 The objective lens (e.g., the objective lens 350) can be configured to operate such that a charged particle beam (e.g., Figure 1 the charged particle beam 122) has a characteristic beam diameter at a focusing position associated with the objective lens (e.g., Figure 2 the focusing position 224) of at least 1 nm, at least 3 nm, at least 5 nm, at least 10 nm, at least 15 nm, at least 20 nm, at least 30 nm, at most 40 nm, at most 25 nm, at most 17 nm, at most 12 nm, at most 7 nm, at most 2 nm, from 1 nm to 7 nm, from 3 nm to 12 nm, from 5 nm to 17 nm, from 10 nm to 25 nm, from 15 nm to 40 nm, from 1 nm to 12 nm, from 3 nm to 17 nm, from 5 nm to 25 nm, from 10 nm to 40 nm, from 1 nm to 17 nm, from 3 nm to 25 nm, from 5 nm to 40 nm, from 1 nm to 25 nm, from 3 nm to 40 nm, and / or from 1 nm to 40 nm.

[0110] Figure 6 is a flowchart depicting an example of a method 600 of operating an objective lens (e.g., Figure 1 the objective lens 150, Figure 2 the objective lens 250, and / or Figure 3 the objective lens 350) and / or a CPM system including such an objective lens (e.g., Figure 1 the CPM system 100). In the following discussion, various components are described in the context of method 600 using terms corresponding to Figures 1 to 3 the components shown and discussed above. Thus, such components described herein with reference to method 600 can be understood to correspond to and / or represent similarly named components referenced above with respect to Figures 1 to 3 As described in more detail below, any suitable portion of method 600 can be performed by a controller of the CPM system, such as Figure 1 the controller 180.

[0111] As Figure 6 shown, method 600 includes positioning a sample relative to the objective lens at 620 and operating the objective lens at 640, such as focusing a charged particle beam to a focusing position. Positioning the sample at 620 can include positioning such that at least a portion of the sample is positioned at the focusing position (e.g., within and / or adjacent to the focusing position).

[0112] Positioning the sample at 620 may include positioning the sample at any one of a variety of focusing working distances and / or sample working distances measured between the objective lens and the sample and / or between the objective lens and the focusing position. As an example, positioning the sample at 620 may include positioning such that the focusing working distance and / or the sample working distance is at least 1 mm, at least 2 mm, at least 5 mm, at least 10 mm, at most 15 mm, at most 7 mm, at most 3 mm, at most 1.5 mm, 1 mm to 3 mm, 2 mm to 7 mm, 5 mm to 15 mm, 1 mm to 7 mm, 3 mm to 15 mm, and / or 1 mm to 15 mm.

[0113] Method 600 may include operating the CPM system to direct a charged particle beam having various beam characteristics to a focusing position and / or to any one of a variety of samples. As an example, operating the objective lens at 640 may include operating such that the impact energy of the charged particle beam measured at the focusing position is at least 5 eV, at least 10 eV, at least 20 eV, at least 30 eV, at least 50 eV, at least 70 eV, at least 90 eV, at least 120 eV, at most 200 eV, at most 150 eV, at most 100 eV, at most 80 eV, at most 60 eV, at most 40 eV, at most 25 eV, at most 15 eV, at most 7 eV, 5 eV to 15 eV, 10 eV to 25 eV, 20 eV to 40 eV, 30 eV to 60 eV, 50 eV to 80 eV, 70 eV to 100 eV, 90 eV to 150 eV, 120 eV to 200 eV, 5 eV to 25 eV, 10 eV to 40 eV, 20 eV to 60 eV, 30 eV to 80 eV, 50 eV to 100 eV, 70 eV to 150 eV, 90 eV to 200 eV, 5 eV to 40 eV, 10 eV to 60 eV, 20 eV to 80 eV, 30 eV to 100 eV, 50 eV to 150 eV, 70 eV to 200 eV, 5 eV to 60 eV, 10 eV to 80 eV, 20 eV to 100 eV, 30 eV to 150 eV, 50 eV to 200 eV, 5 eV to 80 eV, 10 eV to 100 eV, 20 eV to 150 eV, 30 eV to 200 eV, 5 eV to 100 eV, 10 eV to 150 eV, 20 eV to 200 eV, 5 eV to 150 eV, 10 eV to 200 eV, and / or 5 eV to 200 eV.

[0114] Additionally or alternatively, method 600 may include operating a CPM system such that a characteristic beam diameter of a charged particle beam at a focus position is at least 1 nm, at least 3 nm, at least 5 nm, at least 10 nm, at least 15 nm, at least 20 nm, at least 30 nm, at most 40 nm, at most 25 nm, at most 17 nm, at most 12 nm, at most 7 nm, at most 2 nm, from 1 nm to 7 nm, from 3 nm to 12 nm, from 5 nm to 17 nm, from 10 nm to 25 nm, from 15 nm to 40 nm, from 1 nm to 12 nm, from 3 nm to 17 nm, from 5 nm to 25 nm, from 10 nm to 40 nm, from 1 nm to 17 nm, from 3 nm to 25 nm, from 5 nm to 40 nm, from 1 nm to 25 nm, from 3 nm to 40 nm, and / or from 1 nm to 40 nm.

[0115] Additionally or alternatively, operating the objective lens at 640 may include operating to cause an electrostatic lens field generated by the objective lens to have an axial electric field strength of at least 70 V / mm, at least 90 V / mm, at least 120 V / mm, at least 140 V / mm, at least 160 V / mm, at most 175 V / mm, at most 150 V / mm, at most 130 V / mm, at most 100 V / mm, at most 80 V / mm, from 70 V / mm to 100 V / mm, from 90 V / mm to 130 V / mm, from 120 V / mm to 150 V / mm, from 140 V / mm to 175 V / mm, from 70 V / mm to 130 V / mm, from 90 V / mm to 150 V / mm, from 120 V / mm to 175 V / mm, from 70 V / mm to 150 V / mm, from 90 V / mm to 175 V / mm, and / or from 70 V / mm to 175 V / mm.

[0116] As Figure 6 shown, operating the objective lens at 640 may include generating an electrostatic lens field at 642. Generating the electrostatic lens field at 642 may be performed in any suitable manner. For example, generating the electrostatic lens field at 642 may include applying a manipulation electrode voltage to a manipulation electrode at 644. As a more specific example, applying the manipulation electrode voltage at 644 may include applying a manipulation electrode voltage of at least 500 V, at least 1000 V, at least 1500 V, at least 2000 V, at most 2500 V, at most 1700 V, at most 1200 V, at most 700 V, from 500 V to 1200 V, from 1000 V to 1700 V, from 1500 V to 2500 V, from 500 V to 1700 V, from 1000 V to 2500 V, and / or from 500 V to 2500 V.

[0117] In some examples, applying the manipulation electrode voltage at 644 utilizes at least in part a controller of the CPM system (such as Figure 1is executed by the controller 180). For example, applying the manipulation electrode voltage at 644 may include supplying the manipulation electrode voltage to the manipulation electrode using a first voltage source of the controller.

[0118] In some examples, applying the manipulation electrode voltage at 644 includes adjusting the manipulation electrode voltage at 648, such as using the controller. For example, adjusting the manipulation electrode voltage at 648 may include selectively and / or dynamically regulating and / or changing the manipulation electrode voltage using the controller. In this way, applying the manipulation electrode voltage at 644 and / or adjusting the manipulation electrode voltage at 648 may include bringing the manipulation electrode voltage to a target voltage, changing the manipulation electrode voltage to a different target voltage, regulating the manipulation electrode voltage to maintain it at the target voltage, etc.

[0119] In some examples, and as Figure 6 shown, method 600 may include applying an intensifier tube voltage to the intensifier tube at 632. As an example, applying the intensifier tube voltage at 632 may include applying an intensifier tube voltage of 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 kV to 8 kV, 7 kV to 12 kV, and / or 5 kV to 12 kV.

[0120] In various examples, and as described herein, the intensifier tube generates at least a portion of the lens electrostatic field. Thus, in some examples, generating the lens electrostatic field at 642 can be described as including applying an intensifier tube voltage to the intensifier tube at 632.

[0121] In some examples, applying the intensifier tube voltage at 632 is performed at least in part using a controller of the CPM system (such as Figure 1 the controller 180). For example, applying the intensifier tube voltage at 632 may include supplying the intensifier tube voltage to the intensifier tube using a second voltage source of the controller.

[0122] In some examples, applying the intensifier tube voltage at 632 includes adjusting the intensifier tube voltage at 634, such as using the controller. For example, adjusting the intensifier tube voltage at 634 may include selectively and / or dynamically regulating and / or changing the intensifier tube voltage using the controller.

[0123] In some examples, and as Figure 6As shown, operating the objective lens at 640 may include controlling the focusing working distance between the objective lens and the focusing position at 646. In particular, controlling the focusing working distance at 646 may include controlling and / or adjusting one or more operating parameters of the objective lens to adjust and / or change (e.g., increase) the focusing working distance of the objective lens. For example, and as described above, the focusing working distance of the objective lens may be related to the focal length measured with respect to the principal object plane of the objective lens, which in turn may be adjusted by adjusting the manipulation electrode voltage. Thus, in some examples, controlling the focusing working distance at 646 may include applying a manipulation electrode voltage at 644 and / or adjusting the manipulation electrode voltage at 648, and / or may be the result of the above operations. As a more specific example, controlling the focusing working distance at 646 may include applying a manipulation electrode voltage at 644 to bring the manipulation electrode to a target voltage, may include adjusting the manipulation electrode voltage at 648 to change the manipulation electrode voltage to a different voltage, may include (e.g., via a feedback circuit) maintaining the manipulation electrode voltage at the target voltage, etc.

[0124] In various examples, operating the objective lens at 640 includes focusing a charged particle beam to a focusing position. As described herein, such focusing may include focusing with any suitable combination of an electrostatic field and / or a magnetic field (such as may include the lens electrostatic field described herein). As discussed, the lens electrostatic field may include contributions from and / or be modified by an energy booster tube, a manipulation electrode, and / or a shielding electrode. Thus, in some cases, applying an energy booster tube voltage at 632 and / or applying a manipulation electrode voltage at 644 may be described as contributing to focusing the charged particle beam to the focusing position. However, it should be understood that in many examples, such focusing is primarily performed by adjusting the electrostatic field and / or the magnetic field rather than via controlling the energy booster tube voltage and / or the manipulation electrode voltage.

[0125] In some examples, and as Figure 6 shown, method 600 may include adjusting the impact energy of the charged particle beam at the focusing position at 630. For example, and as described above, the impact energy of the charged particle beam may be at least partially based on the source energy of the charged particle source that emits the charged particle beam. Thus, in some examples, adjusting the impact energy at 630 may include adjusting the source energy of the charged particle source.

[0126] In some examples, and as Figure 6 shown, method 600 may include assembling a CPM system including an objective lens at 610. For example, assembling the CPM system at 610 may include positioning the objective lens such that the optical axis of the CPM system extends through each of the shielding electrode and the manipulation electrode.

[0127] In some examples, and as Figure 6As shown, method 600 may include evacuating an experimental chamber at 622, the experimental chamber surrounding at least a portion of a sample, an objective lens, and / or a CPM system. In some examples, evacuating the experimental chamber at 622 may be performed prior to operating the objective lens at 640. In this manner, operating the objective lens at 640 (and / or any other suitable portion of method 600) may be performed while the sample is maintained under vacuum.

[0128] In some examples, and as Figure 6 shown, method 600 may include positioning a sample probe relative to a sample test location of the sample at 650 and / or imaging the sample probe and / or the sample test location at 652 using a CPM system that includes an objective lens in accordance with the present disclosure. In particular, positioning the sample probe at 650 may include the imaging at 652 and / or may be performed in conjunction with the imaging. Positioning the sample probe at 650 may be performed in any suitable manner, such as by moving the sample probe relative to the sample (e.g., using a probe manipulator) and / or by moving the sample relative to the sample probe (e.g., using a sample holder and / or a motion platform).

[0129] Figure 7 The following discussion is intended to provide a brief general description of an exemplary computing environment in which the disclosed technology may be implemented. For example, Figure 7 one or more aspects of the computing system may represent and / or correspond to Figure 1 controller 180 of

[0130] In particular, some or all portions of this computing environment may be used in conjunction with the methods and apparatuses described above to, for example, position a sample probe relative to a sample test location, control a charged particle microscope system to image a sample probe relative to a sample test location, control an objective lens of a CPM system, and / or perform any portion of the methods described above.

[0131] Reference Figure 7 , an exemplary system for implementing the disclosed technology includes a general-purpose computing device in the form of an exemplary PC 700, which includes one or more processing units 702, a system memory 704, and a system bus 706 that couples various system components including the system memory 704 to the one or more processing units 702. The system bus 706 can be any one of several types of bus structures, including a memory bus or memory controller, a peripheral bus, and a local bus using any one of the various bus structures. Exemplary system memory 704 includes read-only memory (ROM) 708 and random access memory (RAM) 710. A basic input / output system (BIOS) 712 is stored in the ROM 708, and the basic input / output system (BIOS) contains basic routines that help transfer information between elements within the PC 700. The PC 700 may represent and / or correspond to Figure 1 controller 180.

[0132] Exemplary PC 700 also includes one or more storage devices 730, such as a hard disk drive for reading from and writing to a hard disk, a disk drive for reading from or writing to a removable disk, and an optical disk drive for reading from or writing to a removable optical disk (such as a CD-ROM or other optical medium). Such storage devices can be connected to the system bus 706 through a hard disk drive interface, a disk drive interface, and an optical disk 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 700. Other types of computer-readable media capable of storing data accessible by the PC can also be used in the exemplary operating environment, such as magnetic tape cartridges, flash memory cards, solid-state drives, digital video discs, CDs, DVDs, RAMs, ROMs, etc. Multiple program modules can be stored in the storage device 730, including: an operating system, multiple operating systems, virtual operating systems, one or more application programs, other program modules, and / or program data.

[0133] Exemplary PC 700 may include various devices configured for a user interface. For example, a user may enter commands and information into PC 700 via one or more input devices 740 such as a keyboard and / or a pointing device such as a mouse. For example, a user may enter commands to initiate image acquisition and / or initiate one or more of the methods disclosed herein. Other input devices may include digital cameras, microphones, joysticks, gamepads, buttons, dials, dish antennas, scanners, etc. These and other input devices are often connected to one or more processing units 702 via a serial port interface coupled to the system bus 706, but may be connected via other interfaces such as a parallel port, game port, universal serial bus (USB), or a wired or wireless network connection. A monitor 746 or other type of display device is also connected to the system bus 706 via an interface such as a video adapter and may display one or more images of a sample or specimen before, after, and / or during the execution of one or more of the methods disclosed herein. The monitor 746 may also be used to select segments or specific image alignments and alignment procedures for processing, such as correlation, feature identification, and preview area selection or other image selection. Other peripheral output devices may be included, such as speakers and printers (not shown).

[0134] PC 700 may operate in a networked environment using a logical connection to one or more remote computers, such as remote computer 760. In some examples, one or more network or communication connections 750 are included. Remote computer 760 may be another PC, server, router, network PC, and / or peer device or other common network node and typically includes many or all of the elements described above with respect to PC 700, although only the memory storage device 762 is illustrated in Figure 7 . A personal computer 700 and / or a remote computer 760 may be connected to a local area network (LAN) and / or a wide area network (WAN). Such networked environments are common in offices, enterprise-wide computer networks, intranets, and the Internet.

[0135] As Figure 7 shown, the memory 790 (or a portion of this memory or other memory) may store processor-executable instructions for adjusting the voltage of an intensifier tube, for adjusting the voltage of a steering electrode, and / or for any other process described herein. For example, such processor-executable instructions may, when executed by a processor system, cause PC 700 and / or another component (e.g., Figure 1 any suitable component of the CPM system 100 of Figure 2 the objective lens 250 of Figure 3The objective lens 350) performs any of the methods disclosed herein. Additionally, the memory 790 may include processor-executable instructions for setting cross-correlation, image alignment such as image rotation and translation, selection of reference images and regions of interest, and / or recording platform coordinates for alignment. In some examples, the processor-executable instructions may generate the displayed images that exhibit segment identification, processing of preview images, and / or acquisition of additional images.

[0136] General considerations

[0137] As used in this application and the claims, the singular forms "a", "an", and "the" include the plural forms unless the context clearly indicates otherwise. Additionally, the term "comprising" means "including". Further, the term "coupled" does not exclude the presence of intermediate elements between the coupled items.

[0138] Unless otherwise specified, as used herein, the term "substantially" refers to 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" refers to the listed values and / or properties and any values and / or properties that differ from the listed values and / or properties by at most 25%. For example, "substantially equal" means exactly equal amounts, as well as amounts that differ from each other by at most 25%.

[0139] The systems, devices, and methods described herein should not be construed as being limited in any way. Instead, the present disclosure relates to all novel and non-obvious features and aspects of the various disclosed examples, either individually or in various combinations and sub-combinations formed with each other. The disclosed systems, methods, and devices are not limited to any particular aspect or feature or combination thereof, and the disclosed systems, methods, and devices do not require the presence of any one or more particular advantages or problem solutions. Any theory of operation is for the purpose of facilitating explanation, but the disclosed systems, methods, and devices are not limited to such a theory of operation.

[0140] Although, for convenience of presentation, the operations of some of the methods disclosed herein are described in a particular order of sequence, it should be understood that such description includes rearrangement unless the specific language described below requires a particular order. For example, the operations described in sequence may in some cases be rearranged or performed simultaneously. Additionally, for simplicity, the drawings may not show the various ways in which the disclosed systems, methods, and devices may be used in combination with other systems, methods, and devices. Further, this description sometimes uses terms such as "generate" and "provide" 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 particular implementation and can be readily discerned by those skilled in the art.

[0141] In some examples, values, procedures, etc. may be characterized by qualifying terms such as "lowest", "optimal", "minimum", "extremely", etc. It should be understood that such descriptions are intended to indicate that a choice can be made among many alternative functions in use, and such a choice does not need to be better, smaller, or otherwise more preferable compared to other choices.

[0142] Innovations may be described in the general context of computer-executable instructions, such as those included in program modules and executed in a computing system on a target 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 functions of program modules may be combined or split among program modules as needed in various examples. The computer-executable instructions for program modules may be executed within a local or distributed computing system. Generally speaking, a computing system or computing device may be local or distributed and may include any combination of dedicated hardware and / or general-purpose hardware and software that implements the functions described herein. Examples of such a computing system or computing device include personal computers, handheld devices, tablet computers, multiprocessor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, virtual machines, containerized applications, etc.

[0143] In various examples described herein, a module (e.g., a component or an engine) may be "programmed" and / or "coded" to perform certain operations or provide certain functions, thereby indicating that the computer-executable instructions for the module can be executed to perform such operations, cause such operations to be performed, or otherwise provide such functions. Although the functions described with respect to software components, modules, or engines may be executed as discrete software units (e.g., programs, functions, class methods), it does not need to be implemented as a discrete unit. That is, the function may be incorporated into a larger or more general program, such as one or more lines of code in a larger or general program.

[0144] The algorithms described above can be embodied, for example, as software or firmware instructions executed by a digital computer. For example, any of the disclosed methods can be executed by one or more of a computer or other computing hardware that is part of a microscopy tool. The computer can be a computer system that includes one or more processors (processing devices) and a tangible, non-transitory computer-readable medium (e.g., one or more optical media disks, 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 can execute computer-executable instructions stored on one or more tangible, non-transitory computer-readable media and thereby perform any of the disclosed techniques. For example, the software for executing any of the disclosed examples can be stored as computer-executable instructions on the one or more volatile non-transitory computer-readable media, which when executed by the one or more processors cause the one or more processors to perform any of the disclosed techniques or subsets of techniques.

[0145] Additional embodiments of the disclosed technology

[0146] The principles of the disclosed techniques have been described and illustrated with reference to exemplary examples, and it should be recognized that the exemplary examples can be modified in arrangement and detail without departing from such principles. For example, example elements executed in software can be implemented in hardware and vice versa. In addition, the techniques from any example can be combined with the techniques described in any one or more of the other examples. It should be understood that processes and functions such as those described with reference to the illustrated examples can be implemented in a single hardware or software module, or separate modules can be provided. The specific arrangements provided above are for convenience of illustration, and other arrangements can be used.

[0147] Example 1. A device, the device comprising: an objective lens, the objective lens comprising: a lens body that circumferentially extends around a lens central axis of the objective lens; a shielding electrode disposed within a downstream end region of the lens body and configured to at least partially shield a test region downstream of the objective lens from a lens electrostatic field generated within the objective lens; and a manipulation electrode disposed within the downstream end region of the lens body and upstream of the shielding electrode, wherein the objective lens is configured such that changing a manipulation electrode voltage applied to the manipulation electrode adjusts a position of a principal object plane of the objective lens in a downstream direction to increase a focusing working distance of the objective lens.

[0148] Example 2. The device according to any of the embodiments herein, particularly embodiment 1, further includes an intensifying tube that extends around the lens central axis upstream of each of the shielding electrode and the manipulation electrode, wherein the intensifying tube is configured to be maintained at an intensifying tube voltage to energize a charged particle beam traveling through the intensifying tube, and wherein the shielding electrode is configured to at least partially shield the test area from the electrostatic field generated by the intensifying tube.

[0149] Example 3. The device according to any of the embodiments herein, particularly embodiment 2, wherein the intensifying tube voltage is one or more of at least 5 kilovolts (kV), at least 7 kV, at least 10 kV, at most 12 kV, at most 8 kV, at most 6 kV, 5 kV to 8 kV, 7 kV to 12 kV, or 5 kV to 12 kV.

[0150] Example 4. The apparatus according to any of the embodiments herein, in particular any one of embodiments 1 to 3, wherein the objective lens is configured to focus a charged particle beam to a focal position corresponding to a sample such that one or more of the following conditions are satisfied: (i) the focal working distance of the objective lens measured along a direction parallel to the central axis of the lens between the objective lens and the focal position is at least 1 millimeter (mm), at least 2 mm, at least 5 mm, at least 10 mm, at most 15 mm, at most 7 mm, at most 3 mm, at most 1.5 mm, one or more of 1 mm to 3 mm, 2 mm to 7 mm, 5 mm to 15 mm, 1 mm to 7 mm, 3 mm to 15 mm, or 1 mm to 15 mm; (ii) the charged particle beam has an impact energy of at least 10 electron volts (eV), at least 20 eV, at least 30 eV, at least 50 eV, at least 70 eV, at least 90 eV, at least 120 eV, at most 150 eV, at most 100 eV, at most 80 eV, at most 60 eV, at most 40 eV, at most 25 eV, at most 15 eV, one or more of 10 eV to 25 eV, 20 eV to 40 eV, 30 eV to 60 eV, 50 eV to 80 eV, 70 eV to 100 eV, 90 eV to 150 eV, 10 eV to 40 eV, 20 eV to 60 eV, 30 eV to 80 eV, 50 eV to 100 eV, 70 eV to 150 eV, 10 eV to 60 eV, 20 eV to 80 eV, 30 eV to 100 eV, 50 eV to 150 eV, 10 eV to 80 eV, 20 eV to 100 eV, 30 eV to 150 eV, 10 eV to 100 eV, 20 eV to 150 eV, or 10 eV to 150 eV measured at the focal position; (iii) the electrostatic field of the lens has an axial electric field strength of at least 70 volts per millimeter (V / mm), at least 90 V / mm, at least 120 V / mm, at least 140 V / mm, at least 160 V / mm, at most 175 V / mm, at most 150 V / mm, at most 130 V / mm, at most 100 V / mm, at most 80 V / mm, one or more of 70 V / mm to 100 V / mm, 90 V / mm to 130 V / mm, 120 V / mm to 150 V / mm, 140 V / mm to 175 V / mm, 70 V / mm to 130 V / mm, 90 V / mm to 150 V / mm, 120 V / mm to 175 V / mm, 70 V / mm to 150 V / mm, 90 V / mm to 175 V / mm, and / or 70 V / mm to 175 V / mm measured at the focal position in a direction parallel to the central axis of the lens;Or (iv) the charged particle beam has a characteristic beam diameter corresponding to the diameter of a circle perpendicular to the lens central axis at the focusing position, the circle containing 50% of the charged particles of the charged particle beam at the focusing position, the characteristic beam diameter being at least 1 nanometer (nm), at least 3 nm, at least 5 nm, at least 10 nm, at least 15 nm, at least 20 nm, at least 30 nm, at most 40 nm, at most 25 nm, at most 17 nm, at most 12 nm, at most 7 nm, at most 2 nm, from 1 nm to 7 nm, from 3 nm to 12 nm, from 5 nm to 17 nm, from 10 nm to 25 nm, from 15 nm to 40 nm, from 1 nm to 12 nm, from 3 nm to 17 nm, from 5 nm to 25 nm, from 10 nm to 40 nm, from 1 nm to 17 nm, from 3 nm to 25 nm, from 5 nm to 40 nm, from 1 nm to 25 nm, from 3 nm to 40 nm, or from 1 nm to 40 nm, or any combination thereof.

[0151] Example 5. The apparatus according to any of the embodiments herein, particularly any one of embodiments 1 to 4, wherein the shielding electrode is configured to be maintained at electrical ground.

[0152] Example 6. The apparatus according to any of the embodiments herein, particularly any one of embodiments 1 to 5, wherein the shielding electrode is directly coupled to the lens body.

[0153] Example 7. The apparatus according to any of the embodiments herein, particularly any one of embodiments 1 to 6, wherein the shielding electrode is electrically coupled to the lens body.

[0154] Example 8. The apparatus according to any of the embodiments herein, particularly any one of embodiments 1 to 7, wherein the shielding electrode extends circumferentially around the lens central axis.

[0155] Example 9. The apparatus according to any of the embodiments herein, particularly any one of embodiments 1 to 8, wherein the shielding electrode is circumferentially symmetric about the lens central axis.

[0156] Example 10. The apparatus according to any of the embodiments herein, particularly any one of embodiments 1 to 9, wherein the shielding electrode includes a shielding electrode aperture through which the lens central axis extends.

[0157] Example 11. The device according to any of the examples herein, particularly Example 10, wherein the shielding electrode includes a shielding electrode central region and a shielding electrode peripheral region, the shielding electrode central region includes the shielding electrode orifice, the shielding electrode peripheral region is radially outside the shielding electrode central region, and wherein the shielding electrode central region extends away from the shielding electrode peripheral region in the downstream direction.

[0158] Example 12. The device according to any of the examples herein, particularly Example 11, wherein the shielding electrode central region is frustoconical.

[0159] Example 13. The device according to any of the examples herein, particularly any one of Examples 11 to 12, wherein the shielding electrode is coupled to the lens body at the shielding electrode peripheral region.

[0160] Example 14. The device according to any of the examples herein, particularly any one of Examples 11 to 13, wherein the manipulation electrode central region extends beyond the lens body in the downstream direction.

[0161] Example 15. The device according to any of the examples herein, particularly any one of Examples 1 to 14, wherein the manipulation electrode voltage is at least 500V, at least 1000V, at least 1500V, at least 2000V, at most 2500V, at most 1700V, at most 1200V, at most 700V, 500V to 1200V, 1000V to 1700V, 1500V to 2500V, 500V to 1700V, 1000V to 2500V, or 500V to 2500V, one or more of these values.

[0162] Example 16. The device according to any of the examples herein, particularly any one of Examples 1 to 15, wherein the manipulation electrode is electrically isolated from the lens body.

[0163] Example 17. The device according to any of the examples herein, particularly any one of Examples 1 to 16, wherein the manipulation electrode is electrically isolated from the shielding electrode.

[0164] Example 18. The device according to any of the examples herein, particularly any one of Examples 1 to 17, wherein the manipulation electrode extends circumferentially around the lens central axis.

[0165] Example 19. The device according to any of the examples herein, particularly any one of Examples 1 to 18, wherein the manipulation electrode is circumferentially symmetric about the lens central axis.

[0166] Example 20. The device according to any of the examples herein, in particular any one of Examples 1 to 19, wherein the manipulation electrode includes a manipulation electrode aperture through which the lens central axis extends.

[0167] Example 21. The device according to any of the examples herein, in particular Example 20, wherein the manipulation electrode includes a manipulation electrode central region and a manipulation electrode peripheral region, the manipulation electrode central region includes the manipulation electrode aperture, the manipulation electrode peripheral region is radially outside the manipulation electrode central region, and wherein the manipulation electrode central region extends away from the manipulation electrode peripheral region in the downstream direction.

[0168] Example 22. The device according to any of the examples herein, in particular Example 21, wherein the manipulation electrode central region is frustoconical.

[0169] Example 23. The device according to any of the examples herein, in particular any one of Examples 21 to 22, wherein the manipulation electrode is coupled to the shielding electrode via the manipulation electrode peripheral region.

[0170] Example 24. The device according to any of the examples herein, in particular any one of Examples 20 to 23, wherein the shielding electrode includes a shielding electrode central region and a shielding electrode peripheral region, the shielding electrode central region includes a shielding electrode aperture, the shielding electrode peripheral region is radially outside the shielding electrode central region, and wherein at least a portion of the manipulation electrode central region is received within the shielding electrode central region.

[0171] Example 25. The device according to any of the examples herein, in particular any one of Examples 1 to 24, the device further includes an electrode bracket that couples the shielding electrode and the manipulation electrode to each other.

[0172] Example 26. The device according to any of the examples herein, in particular Example 25, wherein the electrode bracket supports the manipulation electrode relative to the shielding electrode.

[0173] Example 27. The device according to any of the examples herein, in particular any one of Examples 25 to 26, wherein the electrode bracket comprises an electrically insulating material.

[0174] Example 28. An objective lens, the objective lens comprising: a shielding electrode; and a steering electrode, wherein the objective lens is configured to generate a lens electrostatic field to direct a charged particle beam along an optical axis at least partially to a focusing position, the charged particle beam having an impact energy of at most 100 eV measured at the focusing position, wherein the shielding electrode is configured to at least partially shield a test area downstream of the objective lens such that the lens electrostatic field has an axial electric field strength of at most 150 volts per millimeter (V / mm) measured at the focusing position in a direction parallel to the optical axis, and wherein the steering electrode is configured to generate at least a part of the lens electrostatic field such that the objective lens operates at a focusing working distance of 1 millimeter (mm) to 3 millimeters (mm) measured in a direction parallel to a lens central axis of the objective lens between the objective lens and the focusing position.

[0175] Example 29. The objective lens according to any of the embodiments herein, particularly embodiment 28, wherein the steering electrode is at least partially supported by the shielding electrode.

[0176] Example 30. The objective lens according to any of the embodiments herein, particularly any one of embodiments 28 to 29, the apparatus further comprising an electrode holder directly coupled to each of the shielding electrode and the steering electrode.

[0177] Example 31. The objective lens according to any of the embodiments herein, particularly any one of embodiments 28 to 30, wherein the steering electrode is at least partially received within the shielding electrode.

[0178] Example 32. A charged particle microscope (CPM) system, the charged particle microscope (CPM) system comprising: a charged particle source that emits a charged particle beam along an optical axis and towards a sample; and an objective lens configured to focus the charged particle beam to a focusing position corresponding to a position of the sample, wherein the objective lens comprises the objective lens according to any of the embodiments herein, particularly any one of embodiments 1 to 31.

[0179] Example 33. The CPM system according to any of the embodiments herein, particularly embodiment 32, the CPM system further comprising an energy booster tube extending around the lens central axis upstream of each of the shielding electrode and the steering electrode, wherein the energy booster tube is configured to be held at an energy booster tube voltage to energize the charged particle beam.

[0180] Example 34. The CPM system according to any of the embodiments herein, particularly embodiment 33, wherein when the energy booster tube voltage is applied to the energy booster tube, the energy booster tube generates at least a part of the lens electrostatic field.

[0181] Example 35. A CPM system according to any embodiment herein, particularly any one of embodiments 33 to 34, wherein the CPM system is configured such that the charged particle beam decelerates as it exits the beam booster tube.

[0182] Example 36. A CPM system according to any embodiment herein, particularly any one of embodiments 32 to 35, the CPM system further comprising a sample probe configured to be positioned adjacent a sample test location of the sample, and wherein the shielding electrode is configured to electrostatically shield the sample probe from the lens electrostatic field.

[0183] Example 37. A CPM system according to any embodiment herein, particularly embodiment 36, wherein the sample probe includes a probe tip and a probe beam, the probe tip being configured to be positioned adjacent the sample test location and the probe beam extending away from the probe tip.

[0184] Example 38. A CPM system according to any embodiment herein, particularly embodiment 37, the CPM system further comprising a probe manipulator configured to move the sample probe relative to the sample to position the sample probe adjacent the sample test location, wherein the probe beam extends between the probe tip and the probe manipulator.

[0185] Example 39. A CPM system according to any embodiment herein, particularly any one of embodiments 37 to 38, wherein the probe tip is angled relative to the probe beam towards a sample holder configured to support the sample.

[0186] Example 40. A CPM system according to any embodiment herein, particularly any one of embodiments 36 to 39, wherein the sample probe is configured to directly contact the sample test location.

[0187] Example 41. A CPM system according to any embodiment herein, particularly any one of embodiments 36 to 40, wherein the sample probe is configured to be electrically coupled to the sample test location.

[0188] Example 42. A CPM system according to any embodiment herein, particularly any one of embodiments 36 to 39, wherein the sample probe is configured to be spaced apart from the sample test location during the operational use of the sample probe.

[0189] Example 43. A CPM system according to any embodiment herein, particularly any one of embodiments 36 to 42, wherein the sample probe is configured to be optically coupled to the sample test location.

[0190] Example 44. A CPM system according to any embodiment herein, particularly any one of embodiments 32 to 43, wherein the charged particle beam comprises an electron beam, and wherein the CPM system is configured to operate as a scanning electron microscope (SEM).

[0191] Example 45. A CPM system according to any embodiment herein, particularly any one of embodiments 32 to 44, the CPM system further comprising one or more electron detectors configured to detect electrons emitted from the sample.

[0192] Example 46. A CPM system according to any embodiment herein, particularly embodiment 45, wherein the one or more electron detectors comprise a backscattered electron (BSE) detector configured to detect backscattered electrons generated via an interaction between the charged particle beam and the sample.

[0193] Example 47. A CPM system according to any embodiment herein, particularly embodiment 46, wherein the BSE detector is at least partially positioned within the objective lens.

[0194] Example 48. A CPM system according to any embodiment herein, particularly any one of embodiments 46 to 47, the CPM system further comprising an intensifier tube extending around the lens central axis upstream of each of the shield electrode and the steering electrode, wherein the intensifier tube is configured to be held at an intensifier tube voltage to energize the charged particle beam, and wherein the intensifier tube attracts electrons towards the BSE detector.

[0195] Example 49. A CPM system according to any embodiment herein, particularly any one of embodiments 45 to 48, wherein the one or more electron detectors comprise a secondary electron (SE) detector configured to detect secondary electrons generated via an interaction between the charged particle beam and the sample.

[0196] Example 50. A CPM system according to any embodiment herein, particularly any one of embodiments 32 to 49, the CPM system further comprising one or more scanning coils configured to deflect the charged particle beam to scan the charged particle beam across the sample.

[0197] Example 51. A CPM system according to any of the embodiments herein, particularly any one of embodiments 32 to 50, the CPM system further comprising a condenser lens configured to condense the charged particle beam towards the sample.

[0198] Example 52. A CPM system according to any of the embodiments herein, particularly any one of embodiments 32 to 51, the CPM system further comprising a controller configured to at least partially control the operation of the CPM system.

[0199] Example 53. A CPM system according to any of the embodiments herein, particularly embodiment 52, wherein the controller is configured to at least partially control the operation of the objective lens.

[0200] Example 54. A CPM system according to any of the embodiments herein, particularly any one of embodiments 52 to 53, the CPM system further comprising an intensifier tube extending around the lens central axis upstream of each of the shield electrode and the manipulation electrode, wherein the intensifier tube is configured to be held at an intensifier tube voltage to excite the charged particle beam, and optionally wherein the controller is configured to selectively change the intensifier tube voltage.

[0201] Example 55. A CPM system according to any of the embodiments herein, particularly embodiment 54, wherein the controller comprises a first voltage source configured to apply the intensifier tube voltage to the intensifier tube.

[0202] Example 56. A CPM system according to any of the embodiments herein, particularly any one of embodiments 52 to 55, wherein the controller is configured to selectively change the manipulation electrode voltage applied to the manipulation electrode.

[0203] Example 57. A CPM system according to any of the embodiments herein, particularly any one of embodiments 52 to 56, wherein the controller comprises a second voltage source configured to apply the manipulation electrode voltage to the manipulation electrode.

[0204] Example 58. A CPM system according to any of the embodiments herein, particularly any one of embodiments 52 to 57, wherein the controller is configured to regulate the shield electrode voltage applied to the shield electrode.

[0205] Example 59. A CPM system according to any of the embodiments herein, particularly any one of embodiments 52 to 58, wherein the controller comprises a third voltage source configured to apply the shield electrode voltage to the shield electrode.

[0206] Example 60. A CPM system according to any embodiment herein, particularly embodiment 59, wherein the third voltage source includes an electrical ground.

[0207] Example 61. A CPM system according to any embodiment herein, particularly any one of embodiments 52 to 60, wherein the controller includes one or more input devices for receiving input from a human user to at least partially direct the operation of the CPM system.

[0208] Example 62. A CPM system according to any embodiment herein, particularly any one of embodiments 52 to 61, wherein the controller includes one or more output devices for communicating information to a human user.

[0209] Example 63. A method, the method comprising: positioning a sample relative to an objective lens configured to focus a charged particle beam to a focus position; and operating the objective lens, optionally wherein the objective lens is an objective lens according to any embodiment herein, particularly any one of embodiments 1 to 62.

[0210] Example 64. The method according to any embodiment herein, particularly embodiment 63, wherein positioning the sample includes positioning such that at least a portion of the sample is positioned at the focus position.

[0211] Example 65. The method according to any embodiment herein, particularly any one of embodiments 63 to 64, wherein positioning the sample includes positioning such that the focus working distance measured along a direction parallel to the lens central axis between the objective lens and the focus position is at least 1 millimeter (mm), at least 2 mm, at least 5 mm, at least 10 mm, at most 15 mm, at most 7 mm, at most 3 mm, at most 1.5 mm, 1 mm to 3 mm, 2 mm to 7 mm, 5 mm to 15 mm, 1 mm to 7 mm, 3 mm to 15 mm, or 1 mm to 15 mm.

[0212] Example 66. A method according to any of the examples herein, in particular any one of Examples 63 to 65, wherein the objective lens is included in a CPM system configured to direct the charged particle beam along an optical axis and towards the sample, and wherein the method comprises operating the CPM system such that the impact energy of the charged particle beam measured at the focus position is at least 5 eV, at least 10 eV, at least 20 eV, at least 30 eV, at least 50 eV, at least 70 eV, at least 90 eV, at least 120 eV, at most 200 eV, at most 150 eV, at most 100 eV, at most 80 eV, at most 60 eV, at most 40 eV, at most 25 eV, at most 15 eV, at most 7 eV, 5 eV to 15 eV, 10 eV to 25 eV, 20 eV to 40 eV, 30 eV to 60 eV, 50 eV to 80 eV, 70 eV to 100 eV, 90 eV to 150 eV, 120 eV to 200 eV, 5 eV to 25 eV, 10 eV to 40 eV, 20 eV to 60 eV, 30 eV to 80 eV, 50 eV to 100 eV, 70 eV to 150 eV, 90 eV to 200 eV, 5 eV to 40 eV, 10 eV to 60 eV, 20 eV to 80 eV, 30 eV to 100 eV, 50 eV to 150 eV, 70 eV to 200 eV, 5 eV to 60 eV, 10 eV to 80 eV, 20 eV to 100 eV, 30 eV to 150 eV, 50 eV to 200 eV, 5 eV to 80 eV, 10 eV to 100 eV, 20 eV to 150 eV, 30 eV to 200 eV, 5 eV to 100 eV, 10 eV to 150 eV, 20 eV to 200 eV, 5 eV to 150 eV, 10 eV to 200 eV or one or more of 5 eV to 200 eV.

[0213] Example 67. A method according to any embodiment herein, in particular any one of embodiments 63 to 66, wherein the objective lens is included in a CPM system configured to direct the charged particle beam along an optical axis and towards the sample, and wherein the method comprises operating the CPM system such that the charged particle beam has a characteristic beam diameter corresponding to the diameter of a circle perpendicular to the lens central axis at the focusing position, the circle containing 50% of the charged particles of the charged particle beam at the focusing position, the characteristic beam diameter being at least 1 nm, at least 3 nm, at least 5 nm, at least 10 nm, at least 15 nm, at least 20 nm, at least 30 nm, at most 40 nm, at most 25 nm, at most 17 nm, at most 12 nm, at most 7 nm, at most 2 nm, from 1 nm to 7 nm, from 3 nm to 12 nm, from 5 nm to 17 nm, from 10 nm to 25 nm, from 15 nm to 40 nm, from 1 nm to 12 nm, from 3 nm to 17 nm, from 5 nm to 25 nm, from 10 nm to 40 nm, from 1 nm to 17 nm, from 3 nm to 25 nm, from 5 nm to 40 nm, from 1 nm to 25 nm, from 3 nm to 40 nm, or from 1 nm to 40 nm, or one or more of these ranges.

[0214] Example 68. A method according to any embodiment herein, in particular any one of embodiments 66 to 67, wherein the CPM system is a CPM system according to any embodiment herein, in particular any one of embodiments 32 to 62.

[0215] Example 69. A method according to any embodiment herein, in particular any one of embodiments 63 to 68, wherein operating the objective lens comprises operating to cause the electrostatic lens field to have an axial electric field strength measured at the focusing position in a direction parallel to the lens central axis, the axial electric field strength being at least 70 volts per millimeter (V / mm), at least 90 V / mm, at least 120 V / mm, at least 140 V / mm, at least 160 V / mm, at most 175 V / mm, at most 150 V / mm, at most 130 V / mm, at most 100 V / mm, at most 80 V / mm, from 70 V / mm to 100 V / mm, from 90 V / mm to 130 V / mm, from 120 V / mm to 150 V / mm, from 140 V / mm to 175 V / mm, from 70 V / mm to 130 V / mm, from 90 V / mm to 150 V / mm, from 120 V / mm to 175 V / mm, from 70 V / mm to 150 V / mm, from 90 V / mm to 175 V / mm, and / or from 70 V / mm to 175 V / mm, or one or more of these ranges.

[0216] Example 70. The method according to any of the embodiments herein, particularly any one of embodiments 63 to 69, wherein operating the objective lens includes generating the electrostatic lens field.

[0217] Example 71. The method according to any of the embodiments herein, particularly Example 70, wherein generating the electrostatic lens field includes applying the manipulation electrode voltage to the manipulation electrode.

[0218] Example 72. The method according to any of the embodiments herein, particularly any one of embodiments 70 to 71, wherein the manipulation electrode voltage is at least 500 V, at least 1000 V, at least 1500 V, at least 2000 V, at most 2500 V, at most 1700 V, at most 1200 V, at most 700 V, one or more of 500 V to 1200 V, 1000 V to 1700 V, 1500 V to 2500 V, 500 V to 1700 V, 1000 V to 2500 V, or 500 V to 2500 V.

[0219] Example 73. The method according to any of the embodiments herein, particularly any one of embodiments 70 to 72, the method further includes applying an intensifier tube voltage to an intensifier tube that extends around the lens central axis upstream of each of the shield electrode and the manipulation electrode.

[0220] Example 74. The method according to any of the embodiments herein, particularly Example 73, wherein the intensifier tube voltage is at least 5 kilovolts (kV), at least 7 kV, at least 10 kV, at most 12 kV, at most 8 kV, at most 6 kV, one or more of 5 kV to 8 kV, 7 kV to 12 kV, or 5 kV to 12 kV.

[0221] Example 75. The method according to any of the embodiments herein, particularly any one of embodiments 63 to 74, the method further includes assembling a CPM system including the objective lens before operating the objective lens.

[0222] Example 76. The method according to any of the embodiments herein, particularly Example 75, wherein the CPM system includes a charged particle source configured to emit the charged particle beam along an optical axis, and wherein assembling the CPM system includes positioning the objective lens such that the optical axis extends through each of the shield electrode and the manipulation electrode.

[0223] Example 77. A method according to any of the embodiments herein, particularly any one of embodiments 63 to 76, wherein operating the objective lens includes controlling a focusing working distance between the objective lens and a focusing position of a charged particle beam focused by the objective lens, and optionally wherein controlling the focusing working distance includes applying the manipulation electrode voltage to the manipulation electrode.

[0224] Example 78. A method according to any of the embodiments herein, particularly Example 77, wherein operating the objective lens includes generating the lens electrostatic field, wherein generating the lens electrostatic field includes applying the manipulation electrode voltage to the manipulation electrode, and wherein controlling the focusing working distance includes adjusting the manipulation electrode voltage.

[0225] Example 79. A method according to any of the embodiments herein, particularly any one of embodiments 63 to 78, the method further comprising adjusting an impact energy of the charged particle beam at the focusing position.

[0226] Example 80. A method according to any of the embodiments herein, particularly Example 79, wherein adjusting the impact energy includes adjusting a source energy of a charged particle source of a CPM system including the objective lens.

[0227] Example 81. A method according to any of the embodiments herein, particularly any one of embodiments 63 to 80, the method further comprising: positioning a sample probe adjacent a sample test position of the sample.

[0228] Example 82. A method according to any of the embodiments herein, particularly Example 81, wherein positioning the sample probe adjacent the sample test position includes imaging one or both of the sample probe and the sample test position using a charged particle microscope system including the objective lens.

[0229] Example 83. A method according to any of the embodiments herein, particularly any one of embodiments 81 to 82, wherein positioning the sample probe includes moving the sample probe relative to the sample using a probe manipulator that supports the sample probe relative to the sample.

[0230] Example 84. A method according to any of the embodiments herein, particularly any one of embodiments 81 to 83, wherein positioning the sample probe includes moving the sample relative to the sample probe.

[0231] Example 85. A method according to any of the embodiments herein, particularly any one of embodiments 63 to 84, wherein the objective lens is included in a CPM system including a controller, and wherein the controller executes at least a portion of the method.

[0232] Example 86. The method according to any of the embodiments herein, particularly the method according to embodiment 85, wherein the CPM system is a CPM system according to any of the embodiments herein, particularly any one of embodiments 32 to 62.

[0233] Example 87. The method according to any of the embodiments herein, particularly any one of embodiments 85 to 86, the method further comprising applying an intensifying tube voltage to an intensifying tube extending around the lens central axis upstream of each of the shielding electrode and the steering electrode, and wherein applying the intensifying tube voltage is performed at least in part by the controller.

[0234] Example 88. The method according to any of the embodiments herein, particularly the method according to embodiment 87, wherein applying the intensifying tube voltage includes applying the intensifying tube voltage to the intensifying tube using a first voltage source of the controller.

[0235] Example 89. The method according to any of the embodiments herein, particularly any one of embodiments 87 to 88, wherein applying the intensifying tube voltage includes selectively and / or dynamically adjusting the intensifying tube voltage using the controller.

[0236] Example 90. The method according to any of the embodiments herein, particularly any one of embodiments 85 to 89, wherein operating the objective lens includes generating the lens electrostatic field, wherein generating the lens electrostatic field includes applying the steering electrode voltage to the steering electrode, and wherein applying the steering electrode voltage is performed at least in part by the controller.

[0237] Example 91. The method according to any of the embodiments herein, particularly the method according to embodiment 90, wherein applying the steering electrode voltage includes applying the steering electrode voltage using a second voltage source of the controller.

[0238] Example 92. The method according to any of the embodiments herein, particularly any one of embodiments 90 to 91, wherein applying the steering electrode voltage includes selectively and / or dynamically adjusting the steering electrode voltage using the controller.

[0239] Given the many possible embodiments in which the principles of the disclosed technology can be applied, it should be recognized that the illustrated embodiments are only preferred embodiments and should not be considered as limiting the scope of the disclosed technology. In fact, the scope is defined by the appended claims. Accordingly, we claim all that falls within the scope of these claims.

Claims

1. A device, comprising: An objective lens, comprising: a lens body extending circumferentially around a lens center axis of the objective lens; a shielding electrode disposed within a downstream end region of the lens body and configured to at least partially shield a test region downstream of the objective lens from a lens electrostatic field generated within the objective lens; and a steering electrode arranged in the downstream end region of the lens body and upstream of the shielding electrode, The objective lens is configured such that changing the steering electrode voltage applied to the steering electrode adjusts the position of the main object plane of the objective lens in a downstream direction to increase the focusing working distance of the objective lens.

2. The apparatus of claim 1 , further comprising an energizer tube extending around the lens central axis upstream of each of the shielding electrode and the steering electrode, wherein the energizer tube is configured to be maintained at a booster tube voltage to excite a charged particle beam traveling through the energizer tube, and wherein the shielding electrode is configured to at least partially shield the test region from an electrostatic field generated by the booster tube.

3. The apparatus according to claim 1, wherein the objective lens is configured to focus the charged particle beam to a focus position corresponding to the sample such that: (i) the focus working distance of the objective lens measured between the objective lens and the focus position along a direction parallel to the central axis of the lens is 1 mm to 7 mm; (ii) the charged particle beam has an impact energy of 20 electron volts (eV) to 100 electron volts (eV) measured at the focus position; (iii) the lens electrostatic field has an axial electric field strength of 70 volts per millimeter (V / mm) to 150 volts per millimeter (V / mm) measured at the focus position in a direction parallel to the central axis of the lens; and (iv) the charged particle beam has a characteristic beam diameter corresponding to the diameter of a circle perpendicular to the central axis of the lens at the focusing position, the circle containing 50% of the charged particles of the charged particle beam at the focusing position, and the characteristic beam diameter is at least 1 nanometer (nm) to 7 nanometers (nm).

4. The apparatus of claim 1 , wherein the shield electrode comprises a shield electrode aperture through which the lens central axis extends, wherein the shield electrode comprises a shield electrode central region and a shield electrode peripheral region, the shield electrode central region comprising the shield electrode aperture, the shield electrode peripheral region being radially outward of the shield electrode central region, and wherein the shield electrode central region extends away from the shield electrode peripheral region in the downstream direction.

5. The apparatus of claim 1, wherein the steering electrode is electrically isolated from the shield electrode.

6. An apparatus according to claim 1, wherein the steering electrode comprises a steering electrode orifice through which the central axis of the lens extends, wherein the steering electrode comprises a steering electrode central region and a steering electrode peripheral region, the steering electrode central region comprises the steering electrode orifice, the steering electrode peripheral region is radially outside the steering electrode central region, and wherein the steering electrode central region extends away from the steering electrode peripheral region along the downstream direction. 7 . The apparatus of claim 6 , wherein the steering electrode is coupled to the shielding electrode via the steering electrode peripheral region.

8. The apparatus of claim 6, wherein the shield electrode comprises a shield electrode central region and a shield electrode peripheral region, the shield electrode central region comprising a shield electrode aperture, the shield electrode peripheral region being radially outside the shield electrode central region, and wherein at least a portion of the steering electrode central region is received within the shield electrode central region.

9. The device according to claim 1, further comprising: a charged particle source configured to emit a charged particle beam along an optical axis and toward the sample; The objective lens is configured to focus the charged particle beam to a focusing position corresponding to the position of the sample.

10. The apparatus of claim 9, further comprising a booster tube extending around the central axis of the lens upstream of each of the shield electrode and the steering electrode, wherein the booster tube is configured to be maintained at a booster tube voltage to excite the charged particle beam, and wherein when the booster tube voltage is applied to the booster tube, the booster tube generates at least a portion of the lens electrostatic field.

11. The apparatus of claim 9, further comprising a sample probe configured to be positioned adjacent a sample testing location of the sample, and wherein the shield electrode is configured to shield the sample probe from the lens electrostatic field.

12. The apparatus of claim 9, wherein the charged particle beam comprises an electron beam, and wherein the apparatus is configured to operate as a scanning electron microscope (SEM).

13. An objective lens, comprising: Shielding electrode; and Control electrodes, wherein the objective lens is configured to generate a lens electrostatic field to direct the charged particle beam at least partially along the optical axis to a focus position, the charged particle beam having an impact energy of at most 100 eV measured at the focus position, wherein the shielding electrode is configured to at least partially shield a test area downstream of the objective lens so that the lens electrostatic field has an axial electric field strength of at most 150 volts per millimeter (V / mm) measured in a direction parallel to the optical axis at the focus position, and The steering electrode is configured to generate at least a portion of the lens electrostatic field so that the objective lens operates at a focus working distance of 1 millimeter (mm) to 3 millimeters (mm) measured between the objective lens and the focus position along a direction parallel to a lens center axis of the objective lens.

14. Objective according to claim 13, wherein the steering electrode is at least partially supported by the shielding electrode.

15. Objective according to claim 13, wherein the steering electrode is at least partially received within the shielding electrode.

16. A method comprising: positioning the sample relative to an objective lens configured to focus the charged particle beam to a focus position; as well as operating the objective lens, The objective lens comprises: a lens body extending circumferentially around a lens center axis of the objective lens; a shielding electrode disposed within a downstream end region of the lens body and configured to at least partially shield a test region downstream of the objective lens from a lens electrostatic field generated within the objective lens; and a steering electrode disposed in the downstream end region of the lens body and upstream of the shielding electrode, and Wherein operating the objective lens comprises controlling a focus working distance between the objective lens and the focus position by applying a steering electrode voltage to the steering electrode.

17. The method of claim 16, wherein positioning the sample comprises positioning it so that the focus working distance is 1 mm to 7 mm, and wherein operating the objective lens comprises operating it so that the lens electrostatic field has an axial electric field strength of at most 150 V / mm measured at the focus position in a direction parallel to a central axis of the lens.

18. The method of claim 16, wherein the objective is included in a charged particle microscopy system configured to direct the charged particle beam along an optical axis and toward the sample, and wherein operating the objective comprises operating such that: (i) the impact energy of the charged particle beam measured at the focus position is 5 eV to 200 eV; and (ii) the charged particle beam has a characteristic beam diameter corresponding to the diameter of a circle perpendicular to the central axis of the lens at the focusing position, the circle containing 50% of the charged particles of the charged particle beam at the focusing position, and the characteristic beam diameter is 1 nm to 7 nm.

19. The method of claim 16, further comprising generating the lens electrostatic field, wherein generating the lens electrostatic field comprises applying the steering electrode voltage to the steering electrode, and wherein controlling the focusing working distance comprises adjusting the steering electrode voltage.

20. The method of claim 16, wherein generating the lens electrostatic field comprises applying a booster tube voltage to a booster tube extending around the lens central axis upstream of each of the shield electrode and the steering electrode, and wherein the booster tube voltage is 5 kilovolts (kV) to 12 kilovolts (kV).

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