Rapid mode switching of charged-particle-beam devices

Abstract

A method for rapidly switching between a first imaging or data acquisition mode and a second imaging or data acquisition mode within a charged particle beam (CPB) microscope comprises the steps of: activating a switchable electrostatic multipole element of the CPB microscope to cause or enable the CPB microscope to generate a first set of one or more images or data sets containing information about a sample according to the first imaging or data acquisition mode; and deactivating the switchable electrostatic multipole element to cause or enable the CPB microscope to generate a second set of one or more images or data sets containing information about the sample according to the second imaging or data acquisition mode.

Description

Technology Field

[0001] The present application generally relates to charged particle beam microscopes and charged particle beam microscopy, and more specifically to transmission electron microscopy (TEM) and microscopes for the same, as well as scanning transmission electron microscopy (STEM) and microscopes for the same.

[0002] Inclusion by reference

[0003] All patents, patent application publications, and other published documents mentioned herein are incorporated herein by reference in the same manner as the entirety thereof is fully described herein. Background Technology

[0004] Many biological, chemical, and chemical analysis techniques require the acquisition of spatially resolved data regarding the area or volume distribution of various structures, molecules, and / or elements within one or more samples. Electron microscopy, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM), is recognized as a set of highly versatile techniques for acquiring various useful measurements regarding extremely small samples. In many cases, a single electron microscope device can be configured to acquire complementary measurements of different characteristics of a sample by switching between different operating modes, each mode probing different characteristics of the sample. For example, a TEM device or an SEM can typically operate in both an imaging mode, where the arrangement of features of the sample (e.g., shape, grain boundaries, etc.) can be recorded, and a diffraction mode, where crystallinity, crystal structure, and molecular structure can be determined. Some specially configured SEM and TEM devices can additionally operate in one or more spectroscopic modes (e.g., Energy Dispersive Spectroscopy (commonly abbreviated as EDS), Electron Energy Loss Spectroscopy (abbreviated as EELS), Cathodoluminescence Spectroscopy (CL), etc.), in which the elemental composition or other physical properties of the sample can be determined. A relatively less common operating mode applicable to TEM devices is an alignment mode in which the laser beam is aligned with the electron beam for use with a laser phase plate to enhance image contrast.

[0005] FIG. 1a is a schematic illustration of a conventional axial ray path and field ray path passing through a substage assembly (15) (i.e., an image projection system) of a transmission electron beam microscope, which may be configured as either a sample-image generation mode or a diffraction pattern generation mode. The specific ray path illustrated in FIG. 1a is associated with diffraction pattern generation. An axial ray (4) is generated by electrons that are scattered or otherwise emitted from a sample (not illustrated in FIG. 1a but placed on the sample plane (1)) at an angle to the incident axis (10) of the electron beam (9). These axial ray (4) are focused as a real image on an intermediate image plane (7) by an objective lens system (2). A projection lens system (3), which may include one or more lenses, is placed on the side of the intermediate image plane (7) corresponding to the side opposite to where the electrons are focused into the image plane. Each of the objective lens system (2) and the projection lens system (3) may include a plurality of individual lenses, but for simplification, only one representative lens is shown in each case, and the same applies to other cases where lenses are mentioned in this specification. As shown in FIG. 1a, the projection lens system (3) is positioned and operated such that the focal length of the projection lens system is greater than the distance between the intermediate image plane (7) and the projection lens system (3).

[0006] Under the operation illustrated in FIG. 1a, the axial beam (4) is not focused at the detector plane (8), and thus no image of the sample is formed. Instead, the field beam (5) of the electron beam (9) is focused at the detector plane. The field beam (5) enters and passes through the objective lens (2) along a trajectory substantially parallel to the electron microscope column axis (10). The objective lens system (2) causes the field beam (5) to focus at the back focal plane (6) of the objective lens. If the field beam electron does not interact with the sample in any way that changes its trajectory, a single small spot, which is an image of the electron source (not shown in the drawing), will be created at the back focal plane (6) of the objective lens by the focusing action. However, the actual image appearing at the back focal plane (6) is very sensitive to some angular deviation of the beam that may occur as a result of the interaction between the electron and the sample. These interactions involve electron scattering, and in the case of crystalline samples, particularly electron diffraction, which is illustrated as a scattering beam cone (105) in FIG. 1b, which is an enlarged portion of FIG. 1a. Thus, in the case of a crystal, the actual image at the back focal plane (6) includes a plurality of focused spots, each spot being generated by an individual diffracted beam.

[0007] The arrangement and operation of the projection lens system (3) described above is such that the focused image of the back focal plane (6) is transmitted to or formed on the detector plane (8) so as to be acquired as a diffraction pattern. During the acquisition of the diffraction pattern, an adjustable aperture is positioned on the intermediate image plane (7) (also known as the “selected aperture” plane) to control the sample area where the diffracted electron beam is collected. Thus, the intermediate image plane is also commonly referred to as the “selected aperture” plane. Note that FIG. 1a is illustrated in a very schematic manner. In actual practice, the substage assembly (15) may include one or more additional lenses that magnify or correct the image projected onto the detector plane (8). In order to obtain an image of the sample rather than a diffraction pattern, the intensity of the transmission lens system (3) and any additional substage lenses can be typically adjusted by adjusting the lens current of the magnetic lens so that the actual image of the sample formed in the intermediate image plane (7) by the axial rays (4, 104) is preferably projected onto the detector plane in an enlarged form. This adjustment simultaneously causes the field of view rays (5) to be out of focus on the detector plane.

[0008] Conventional methods for switching between imaging modes and diffraction modes have been advantageously used in TEM research for many years for the purpose of studying the interatomic structures of various molecular and crystalline materials. However, it has recently been recognized that conventional mode switching methods are insufficient for research where both modes must be available simultaneously or where extremely rapid switching between the two modes is required. For example, U.S. Publication 2021 / 0302333-A1 describes a method for determining phase information in addition to intensity information from electrons observed on a diffraction plane by interfering a second reference electron beam and an electron beam generated simultaneously. To implement this method, the inventors of the said publication application utilized a TEM system comprising a "bifocal beamformer" device as described in U.S. Publication 2021 / 0305007-A1. Referring to the same bifocal beamformer device, U.S. Publication 2021 / 0305010-A1 teaches a method of simultaneously aiming two electron beams at a sample and performing both diffraction and imaging to identify movement of the sample during the process of progressively tilting the sample while collecting data for three-dimensional molecular or crystallographic reconstruction.

[0009] FIG. 2 illustrates a bifocal multibeam charged particle transmission microscope system (100) as described in U.S. Publication 2021 / 0305010-A1. The illustration in FIG. 2 is a schematic cross-sectional view of the microscope system taken parallel to the xz plane (by convention, the z-axis is assumed to be parallel to the principal axis (110) (typically oriented vertically) of the optical column not illustrated in the system (100)). Components housed within the optical column are provided to form two charged particle beams having different focusing characteristics. The optical column includes a charged particle source (106) and other optical components such as a bifocal beamformer (112), a focusing component (120), a focusing column (126), a multipolar element (124), and a mini-condenser optical system (128). In some examples, one or more lenses are placed between the charged particle source (106) and the bifocal beamformer, which allows the current in both beams to be adjusted. These lenses are preferably electrostatic lenses.

[0010] According to the teaching of U.S. Publication 2021 / 0305010-A1, a charged particle beam (111) generated by a charged particle source (106) is split into a first charged particle beam (101) and a second charged particle beam (102) by a bifocal beamformer positioned downstream of the charged particle source (106). The first charged particle beam (101) is an axial beam that travels along the principal axis (110) of an optical column. The principal axis (110) may be the emission axis of the charged particle source (106). The second charged particle beam (102) is a non-axial beam that travels along an axis (161) different from the principal axis (110). The bifocal beamformer (112) changes the focal characteristics of at least one of the first and second charged particle beams so that the first and second charged particle beams have different focal characteristics. The bifocal beamformer (112) changes the focal characteristic of at least one of the first and second charged particle beams so that the first and second charged particle beams have different focal characteristics.

[0011] According to the teachings of U.S. Publication 2021 / 0305010-A1, a bifocal beamformer may be a microelectromechanical system (MEMS) or an aperture lens array. To change the focusing characteristics of at least one charged particle beam, the bifocal beamformer may apply a quadrupole lens action to at least one charged particle beam to focus at least one beam, correct astigmatism, and / or otherwise modify it so that the corresponding focusing characteristics of the beams are different from each other. The quadrupole lens action may focus a second charged particle beam in the xz plane and expand a second charged particle beam in the yz plane. The bifocal beamformer may additionally be configured to generate at least a bipolar electromagnetic field that causes at least one beam to be deflected.

[0012] After exiting the bifocal beamformer (112), the first and second charged particle beams sequentially pass through a focusing component (120), a multipolar element (124), a focusing column (126), a condenser optical system (128), and a sample-front objective lens (130) before irradiating the sample (14). When the sample is not tilted, the sample (14) is positioned on the sample plane (154). The sample plane (154) is a plane orthogonal to the main axis (110). The focusing component (120), positioned downstream of the bifocal beamformer, accelerates / decels, focuses, and / or directs the first charged particle beam (101) and the second charged particle beam (102) toward the focusing column (126), positioned downstream of the focusing component (120). The focusing component (120) may include an accelerator (122) that focuses and accelerates a beam of charged particles.

[0013] A multipolar element (124) is positioned between a focusing component (120) and a focusing column (126) at the focal plane of the first charged particle beam to adjust the beam shape of the second charged particle beam. The multipolar element (124) does not affect the first charged particle beam. The multipolar element (124) may be a stigmatizer that applies a quadrupole lens action complementary to the quadrupole lens action of the bifocal beamformer to make the second charged particle beam profile cylindrically symmetric. The combined action of the bifocal beamformer (112) and the multipolar element (124) causes the first and second charged particle beams to have different focal planes near the sample plane (154).

[0014] As taught in U.S. Publication 2021 / 0305010-A1, a focusing column (126) and a condenser optical system (128) bring a deflected second charged particle beam close to the principal axis (110). The first charged particle beam and the second charged particle beam are focused in different planes (152, 151) upstream of the sample-front objective lens (130). After passing through the sample-front objective lens (130) positioned downstream of the condenser optical system (128), the first charged particle beam and the second charged particle beam illuminate the entire region of interest of the sample. The beam axes of the first and second charged particle beams may intersect each other at the sample plane (154). Either of the first and second charged particle beams may be in a convergent (e.g., focused) or non-convergent state at the sample plane. The second charged particle beam is incident on the sample (14) mounted on the sample holder (13) so as to have a non-zero tilt angle with respect to the first charged particle beam.

[0015] The detector (144) is positioned downstream of the projection optical system (132), and the diffraction pattern is focused to the detector through the sample-post objective lens (131) and the projection optical system (132). The sample-previous objective lens (130) and the sample-post objective lens (131) can be combined with a magnetic immersion lens. The non-scattered beam can be blocked by a beam stopper (17) positioned between the projection optical system (132) and the detector (144). Scattered charged particles (103) pass through the projection lens (132) and form a diffraction pattern in the first region of the detector (144). The collected scattered charged particles (e.g., scattered electrons) form a diffraction pattern such as a selected area electron diffraction (SAED) pattern. A second charged particle beam forms a sample image in the second region of the detector (144). The first region and the second region are spaced apart from each other. That is, the center positions of the first region and the second region are different. The overall magnification of the bifocal image, which can include both the sample image and the diffraction pattern, can be adjusted by a projection system. The sample image can represent the two-dimensional contour or shape of the crystal.

[0016] To use the aforementioned bifocal beamformer device within a transmission electron microscope, complex modifications to the existing microscope are required, incurring additional costs. Furthermore, known charged particle beam mode switching techniques are burdened by hysteresis effects that delay the start of reliable data acquisition following the switching event. Faster mode switching is required to examine certain samples that move, degrade, break down, react, or undergo other changes (intentionally or unintentionally) during microscopic observation. Therefore, there is a need in the field of charged particle beam microscopy technology for a more rapid method of switching between imaging and diffraction modes using simple components that do not require significant modifications to existing systems. The problem to be solved

[0017] The inventors have recognized that rapid switching of operating modes can be achieved by activating and deactivating a few additional capacitive multipole components (e.g., a single capacitive multipole component) and optionally, one or more stigmatizer components (i.e., magnetic multipoles) integrated into the charged particle beam path of an electron microscope, otherwise conventionally. In particular, the capacitive multipole components can be rapidly switched between an activated state and a deactivated state. For example, using such switchable capacitive multipole components, a switching time of less than 50 nanoseconds can be achieved at the time of writing this specification, thereby enabling a cycle time of less than 100 nanoseconds. Using such rapidly switchable optical systems, it is possible to generate pseudo-simultaneous superimposed charged particle beam images, wherein each image is acquired using a different operating mode. As used herein, the term “pseudo-simultaneous” means that two or more modes can be generated with a specific duty cycle (e.g., a 1:10 duty cycle using two overlapping modes determined by the user) within a typical camera frame time (e.g., 1 ms to 10 ms). For example, when using Scanning Transmission Electron Microscopy (STEM), it is attractive to generate a diffraction pattern during the beam flyback time. means of solving the problem

[0018] According to a first aspect of the present disclosure, a method for rapidly switching between a first imaging or data acquisition mode and a second imaging or data acquisition mode within a charged particle beam (CPB) microscope is described, the method comprising:

[0019] A step of activating a switchable multipole element of a CPB microscope configured to generate a quadruple theater when activated, thereby causing the CPB microscope to generate a first set of one or more images or data sets containing information about a sample according to a first imaging or data acquisition mode, or enabling the generation of said first set; and

[0020] A step of deactivating the switchable multipole element to cause the CPB microscope to generate a second set of one or more images or data sets containing information about the sample according to a second imaging or data acquisition mode, or to enable the generation of the second set.

[0021] The switchable multipole element may be a switchable capacitive multipole element. The switching time of the switchable capacitive multipole element may be 100 milliseconds or less, or alternatively 10 milliseconds or less, or alternatively 1 millisecond or less, or alternatively 500 microseconds or less, or alternatively 10 microseconds or less, or alternatively 1 microsecond or less, or alternatively 500 nanoseconds or less, or alternatively 50 nanoseconds or less. The switchable multipole element configured to generate a quadrupole field may be placed on or near a selected aperture plane of a substage assembly of a charged particle beam microscope system. Optionally, an additional multipole element (stigmatizer or capacitive multipole element) may be placed on or near the back focal plane of a focusing lens of the substage assembly. The additional multipole element may remain in an active state while the switchable multipole element on or near the selected aperture plane is switched from an active state to an inactive state or vice versa.

[0022] According to some embodiments, the switching time of the switchable multipole element is 100 milliseconds or less, or alternatively 10 milliseconds or less, or alternatively 1 millisecond or less, or alternatively 500 microseconds or less, or alternatively 10 microseconds or less, or alternatively 1 microsecond or less, or alternatively 500 nanoseconds or less, or alternatively 50 nanoseconds or less.

[0023] According to some embodiments, the switchable capacitive multipole element is repeatedly activated and deactivated within a single detector frame time according to a duty cycle, wherein each activation causes the CPB microscope to generate a compositional image according to a first imaging mode, each deactivation causes the CPB microscope to generate a compositional image according to a second imaging mode, and the superposition of the compositional images generates a multi-exposure composite image. According to some embodiments, the switchable capacitive multipole element is repeatedly activated and deactivated within a single detector frame time according to a duty cycle, wherein each activation causes the CPB microscope to generate a compositional image according to a first imaging mode, each deactivation causes the CPB microscope to generate a compositional image according to a second imaging mode, and the superposition of the compositional images generates a multi-exposure composite image.

[0024] Each activation and deactivation of the above-mentioned switchable electrostatic multipole element includes each activating and deactivating the electrostatic multipole element located on the selected aperture plane of the objective lens system of the image projection system.

[0025] Here, each activation corresponds to the generation of an image of the sample, and each deactivation corresponds to the generation of an electron diffraction pattern from the sample.

[0026] An alternative embodiment may include a pair of active stigmats positioned between the back focal plane and the projection lens instead of a single stigmat. The single stigmat or, alternatively, the pair of stigmats may be maintained in an active state while a switchable capacitive multipole is repeatedly activated and deactivated.

[0027] According to various other embodiments in which a switchable electrostatic multipole element is disposed within an image projection system of a CPB microscope, the image projection system may include a laser phase plate conjugated to a back focal plane and disposed on or near a diffraction plane where the laser beam is directed.

[0028] Here, each activation and deactivation includes activating and deactivating a switchable electrostatic multipole element disposed on or near the image plane conjugated to the sample plane, respectively.

[0029] Each activation causes the superimposed image of the sample and the laser interference pattern to be acquired by the detector.

[0030] According to various other embodiments of the first aspect of the present disclosure, the switchable electrostatic multipole element may be disposed within a CPB microscope column that directs a charged particle beam onto a sample. In such an embodiment, the switchable electrostatic multipole element may be disposed between the focal point of the beam focusing lens system of the CPB microscope column and the aberration correction system of the CPB microscope column, and

[0031] Activation of the above-mentioned switchable electrostatic multipole element enables the CPB microscope column to deliver a focused probe beam onto the sample, enabling a scanning transmission microscope (STEM) operating mode, and

[0032] Deactivation of the above-mentioned switchable electrostatic multipole element allows the CPB microscope column to deliver a parallel (or nearly parallel) beam onto the sample, enabling a transmission electron microscope (TEM) operating mode.

[0033] In some cases, the focused probe beam may be focused into a spherical probe beam of sub-Angstrom diameter that is delivered to a selected point on the sample. The aberration correction system may include a hexapole-type spherical aberration corrector comprising two active magnetic hexapole elements that generate negative spherical aberration correction.

[0034] According to a second aspect of the present disclosure, a charged particle beam (CPB) microscope is provided, said CPB microscope comprises:

[0035] Charged particle beam source;

[0036] A CPB column configured to transmit a charged particle beam from a charged particle beam source to a sample;

[0037] An optical assembly comprising a transfer optical system configured to transmit charged particles transmitted through a sample or scattered by the sample to a detector; and

[0038] As a switchable electrostatic multipole member of either the CPB column or the optical assembly, the switchable electrostatic multipole member is configured to generate a quadruplet when activated,

[0039] Activation of the above-mentioned switchable electrostatic multipole member enables the CPB microscope to generate a first set of one or more images or data sets containing information about a sample according to a first imaging or data acquisition mode, or enables this.

[0040] Deactivation of the above-mentioned switchable electrostatic multipole member causes the CPB microscope to generate a second set of one or more images or data sets containing information about the sample according to a second imaging mode, or enables this.

[0041] This first CPB microscope is provided as a transmission electron microscope (TEM) comprising the following:

[0042] An image projection system comprising the following configuration:

[0043] An objective lens system configured to receive electron beams from a sample and having a back focal plane;

[0044] A projection lens system positioned between the objective lens system and the detector; and

[0045] A switchable electrostatic multipole element located at or near the intermediate image plane (e.g., selected aperture plane) of the above objective lens system and configured to generate a quadruplet,

[0046] Here, activation of the switchable electrostatic multipole element causes an image of the sample to be projected onto the detector, and deactivation of the electrostatic multipole element causes a diffraction pattern from the sample to be projected onto the detector.

[0047] The image projection system of the above TEM may further include the following:

[0048] A stigmat or a second electrostatic multipole element located at or near the rear focal plane of the objective lens system and configured to generate a quadruplet when activated,

[0049] Here, the stigmatizer or the second electrostatic multipole element is maintained in an activated state during the activation and deactivation of the switchable electrostatic multipole element.

[0050] According to a third aspect of the present disclosure, a charged particle beam column of a transmission electron microscope (TEM) or scanning transmission microscope (STEM) system is provided, comprising:

[0051] It includes a switchable electrostatic multipole element configured to generate a quadruple theater and also configured to be alternately activated and deactivated, positioned near a first lens system of a probe beam delivery system, wherein the first lens system is configured to receive a diverging beam from a focusing lens system of an electron microscope.

[0052] Here, the activation of the switchable multipole element enables the focused charged particle probe beam to be delivered from the charged particle beam delivery system onto the sample, and the deactivation of the quadrupole enables the collimated charged particle beam to be delivered from the charged particle beam delivery system onto the sample.

[0053] The above charged particle beam column may further include the following:

[0054] A six-pole type spherical aberration corrector comprising two magnetic six-pole elements disposed between the switchable four-pole and the sample and generating negative spherical aberration correction.

[0055] According to a fourth aspect of the present disclosure, an improved substage assembly for a transmission electron microscope (TEM) is provided, comprising: an objective lens system; a first transfer lens system located downstream of the back focal plane of the objective lens system; a second transfer lens system positioned in or near the intermediate image plane formed by the objective lens system and the first transfer lens system; a laser phase plate positioned near the intermediate diffraction plane; and a laser that directs a laser beam onto the laser phase plate; wherein the improvements include:

[0056] A switchable multipole element configured to generate a quadruple theater when activated, positioned near the intermediate image plane, and configured to be repeatedly activated and deactivated.

[0057] According to any one of the above-described embodiments of the present disclosure, a switchable multipole element or member configured to generate a quadrupole theater when activated may comprise a simple quadrupole element or member. Likewise, according to any one of the above-described embodiments, a switchable capacitive multipole element or member configured to generate a quadrupole theater when activated may comprise a simple capacitive quadrupole element or member.

[0058] According to any one of the above-described embodiments of the present disclosure, a switchable electrostatic multipole element or member configured to generate a quadruple theater may have a switching time from an inactive state to an active state or from an active state to an inactive state of 100 milliseconds or less, or alternatively 10 milliseconds or less, or alternatively 1 millisecond or less, or alternatively 500 microseconds or less, or alternatively 10 microseconds or less, or alternatively 1 microsecond or less, or alternatively 500 nanoseconds or less, or alternatively 50 nanoseconds or less. Brief explanation of the drawing

[0059] The above-described embodiments and various other embodiments of the present invention will be apparent from the following description, which is merely illustrative and given with reference to the accompanying drawings, and the drawings are not necessarily drawn to actual scale: FIG. 1a is a schematic illustration of the axial ray path and the field ray path passing through the substage assembly of a transmission electron microscope (e.g., transmission electron microscope, TEM) configured in a conventional manner to display the diffraction pattern of a sample; FIG. 1b is an enlarged view of a portion of FIG. 1a; FIG. 2 is an example of a known bifocal multibeam charged particle system configured to simultaneously provide first and second charged particle beams capable of providing an image of a sample from a first charged particle beam and diffraction information regarding a sample from a second charged particle beam; FIG. 3a is a schematic illustration of an axial path passing through a version of the substage assembly of FIG. 1a modified by including two switchable electrostatic quadrupole optical components according to the present teaching, said components allowing an electron diffraction pattern to be acquired by a detector when activated and an image of a sample to be projected onto a detector when deactivated; FIG. 3b is a schematic illustration of the field ray path passing through the modified substage assembly of FIG. 3a when both electrostatic quadrupole optical components are activated; FIG. 4 is a schematic illustration of a field ray path passing through a second modified version of the substage assembly of FIG. 1a, modified according to the present teaching by including a stigmatizer on the back focal plane of the objective lens and including one electrostatic quadrupole optical component, wherein an electron diffraction pattern is acquired by a detector when the electrostatic quadrupole is not activated; FIG. 5a is an image of a sample generated by an electron microscope substage assembly in which the optical components are arranged as in FIG. 4, but there are two stigmatizers and the quadrupole element is deactivated; FIG. 5b is a diffraction pattern acquired using the same system and the same sample as imaged in FIG. 5a, but with the electrostatic quadrupole component activated; FIG. 6a is a part of a set of optical components within a portion of an electron beam illumination column configured and operated in a manner known to deliver a collimated electron beam onto a sample to enable a transmission electron microscope (TEM) operating mode; FIG. 6b is a modified version of the optical component of FIG. 6a modified by including an additional switchable electrostatic quadrupole component according to the present teaching, wherein the illustrated light beam is converted into a converging light beam at the sample and the beam is focused into a small spot size (sub-angstroms small), thereby enabling the detection of a high-magnification image of the sample in scanning transmission electron microscope (STEM) operating mode; FIG. 7a is a schematic illustration of a portion of a set of substage components of a transmission electron beam microscope provided in a known configuration including a laser phase plate for image contrast enhancement; FIG. 7b is a modified version of the substage component of FIG. 7a modified according to the present teaching by including a switchable capacitive quadrupole element on or near the first image plane following the objective lens, wherein activation of the quadrupole causes two field ray focal points to form on opposite sides of the laser phase plate, thereby allowing imaging of a laser fringe for the purpose of sample alignment; FIG. 8 is a collection of fringe patterns obtained using a TEM substage configuration that includes both a laser phase plate placed on the diffraction plane and a quadrupole mode switching device placed upstream of the laser phase plate; the horizontal and vertical panels show the effect of exciting the quadrupole into two distinct orientations; FIG. 9a is a composite image acquired during a readout of a STEM detector, where the capacitive quadrupole is activated to focus the field of view light for 50% of the time (as in FIG. 7b) and deactivated for the remaining 50% of the time (as in FIG. 7a); the result is obtained by applying an on / off square wave voltage profile with a 50-hertz period to the internal quadrupole; FIG. 9b is a composite TEM image including the diffraction image and ronchigram of the STEM probe used during image acquisition of FIG. 9a; FIG. 9c is a schematic illustration of the voltage waveform applied during the acquisition of the composite image of FIG. 9a; FIG. 10 is a set of block diagrams of a controller and a power supply for a microscope system according to a specific embodiment of the present disclosure; FIG. 11 illustrates a known Micro-Electrical Mechanical System (MEMS) bifocal beamforming device that can be modified for use as a MEMS electrostatic quadrupole within the present invention; FIG. 12 illustrates a top-down schematic diagram of another MEMS bifocal beamforming device; FIG. 13a illustrates a top-down schematic diagram of another known MEMS bifocal beamforming device comprising seven electrodes that can be modified for use as a MEMS electrostatic quadrupole within the present invention; FIG. 13b illustrates a modified form of the MEMS device of FIG. 13a that can be employed as an electrostatic quadrupole within the present invention. Specific details for implementing the invention

[0060] The following description is provided to enable those skilled in the art to manufacture and use the invention and is provided in the context of a specific patent application and its requirements. Various modifications to the described embodiments will be readily apparent to those skilled in the art, and the general principles of this specification may be applied to other embodiments. Accordingly, the invention is not intended to be limited to the illustrated embodiments and examples, and should be given the broadest possible scope based on the features and principles illustrated and described. To fully understand the features of the invention in more detail, please refer to FIGS. 1 through 13 together with the following description.

[0061] In the description of the invention in this specification, words appearing in the singular form include their plural counterparts, and words appearing in the plural form are understood to include their singular counterparts, unless implicitly or explicitly understood or stated otherwise. Furthermore, for any given component or embodiment described in this specification, any of the possible candidates or alternatives listed for said component may generally be used individually or in combination with one another, unless implicitly or explicitly understood or stated otherwise. Additionally, it should be understood that the drawings in this specification are not necessarily drawn to scale, and some elements may be drawn merely for clarity of the invention. Also, reference numbers may be repeated in multiple drawings to indicate corresponding or similar elements. The list of candidates or alternatives is merely illustrative and not restrictive, unless implicitly or explicitly understood or stated otherwise.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the meanings commonly understood by those skilled in the art to which the present invention pertains. In the event of a conflict, the present specification, including definitions, shall prevail. It will be understood that any quantitative term mentioned herein is preceded by an implied “about,” and that minor and non-substantial deviations are within the scope of this teaching. Whenever “substantially,” “about,” “about,” or similar language is explicitly used with a specific value, a variation of up to 10% of that value is intended unless otherwise specified. Furthermore, the use of “constitute,” “constitutes,” “constituting,” “containing,” “containing,” “containing,” “includes,” “includes,” and “includes” is not intended to be restrictive. As used herein, “one” may also refer to “at least one” or “one or more.” In addition, the use of "or" is inclusive, so the phrase "A or B" is true when "A" is true, "B" is true, or both "A" and "B" are true.

[0063] As used herein, the term “stigmator” is used to refer only to magnetic multipole optical components, and the terms “quadruple” and “multipole” are used to refer only to electrostatic multipole optical components, except that these terms are not intended to refer to dipole optical components. As used herein, the terms “activated” and “activated” used in relation to a component of a charged particle beam microscope located at a specific location within the charged particle beam microscope refer to applying one or more of a first set of voltages to the electrodes of the component to modify the trajectory of a charged particle passing through or over the component, compared to the trajectory that would have existed if the component were not located at that location, so that a first desired mode of operation is achieved. As used herein, the terms “deactivated” and “deactivated” as used in relation to such components at a given location refer to applying one or more of a second set of voltages (or no voltage) to the electrodes of said components such that the trajectory of a charged particle passing through or over said component is essentially identical to the trajectory when said component is not actually present at that location, thereby achieving a second desired mode of operation. In the foregoing, the phrase “making the trajectory of a charged particle … essentially identical to the trajectory when said component is not present at that location” means that the particle trajectory is sufficiently similar to the trajectory realized in the absence of the component, to the extent that the data collected in the second desired mode of operation is similar to the data collected when said component is not present, at a threshold of a similarity metric and / or a threshold of a data quality metric. Any suitable similarity metric or quality metric may be used.

[0064] In this specification, the use of optical-related terms such as “optical,” “optical,” “beam,” “beam path,” “ray,” “lens,” “focus,” “collimate,” etc., is not intended to imply that such optical systems, optical components, beams, rays, lenses, focus, collimation, etc., are related to or intended to manipulate photons (i.e., visible and invisible light). Furthermore, the use of these terms does not imply the use of photon-transmitting materials, such as silica or fluorite, for the purpose of manipulating various beams, rays, etc. Instead, as used in this specification, these terms relate to beams and rays of charged particles (generally electrons) and also relate to the control of the trajectories of such charged particles by other components including electromagnetic lenses, objective lenses, stigmats, and electrodes. As used in this specification, the term “quadruple” includes a multipole device (e.g., sextruple, octruple, etc.). It includes a multipole device configured primarily to generate a quadruple field. As used herein, a quadrupole device may include either an electrostatic quadrupole or a magnetic quadrupole. Additionally, the term “substage optical system” as used herein refers to an optical lens and / or other optical component used to divert a beam of charged particles and its ray path after passing through a sample, or to manipulate it otherwise, regardless of the relative position between the sample and said optical lens and / or other optical component (i.e., above, below, across, etc.).

[0065] FIGS. 3a and 3b are schematic illustrations of an axial ray path and a field ray path passing through a modified version (15a) of the substage assembly of FIG. 1a, modified according to the present teaching. Specifically, the substage assembly (15a) is modified from a conventional assembly (e.g., FIG. 1a) by including a first electrostatic quadrupole optical component (13a) positioned at the rear focal plane (6) of the objective lens system (2), and a second electrostatic quadrupole optical component (13b) positioned at the intermediate image plane (7) (i.e., a selected aperture plane of the objective lens system (2)). The first electrostatic quadrupole (13a) is optional and, if present, may remain active during a mode switching operation. Alternatively, the first quadrupole (13a) may be a magnetic quadrupole (i.e., a stigmat) that remains active throughout the operation. The second quadrupole (13b) is an electrostatic quadrupole and can be operated in either a "deactivated" state or an "activated" state for the purpose of switching modes.

[0066] FIGS. 3a and 3b illustrate the light paths of axial light electrons and field light electrons, respectively, when the electrostatic quadrupoles (13a, 13b) are simultaneously active. It should be noted that only a selected few of the light rays are depicted in these figures and other attached figures. Each point on the sample illuminated by the electron beam (9) will generate a number of light rays emitted from the sample in a conical configuration. The light rays depicted in FIGS. 3a and 3b, as well as in other attached figures, represent only a selected few of the light rays emitted from the same common point on the sample (on the sample surface (1)). As shown in FIG. 3a, the first electrostatic quadrupole (13a) is configured to separate and convert each axial light into a first sub-light (4a) in the XZ plane and a second sub-light (4b) in the YZ plane.

[0067] When activated, the second quadrupole causes the trajectory of each ray (4a) in the x, z plane to propagate at the same distance from the axis (10) as the corresponding ray (4b) in the y, z plane between the second quadrupole and the detector (8). Thus, this figure shows that the axial ray is circular when passing through the second electrostatic quadrupole (13b) and the projection lens (3) (note that the vertical axis in Figures 3a and 3b corresponds to both x and y dimensions). After passing through the second electrostatic quadrupole, the projection of the axial ray is superimposed and is represented as ray (4ab). The axial ray (4ab) is then focused as an image of the sample on the detector plane (8). Thus, when the two electrostatic quadrupoles (13a, 13b) are configured in an activated state as shown, the sample plane and the detector plane become conjugate with each other, and thus the image of the sample is projected onto the detector and recorded. The inventors have discovered that when the first electrostatic quadrupole (13a) is removed, deactivated, or otherwise absent, an astigmatism image of the sample can be projected onto the detector as a useful overview image. In this situation, the beam deflection intensity of the single quadrupole (13b), controlled by the voltage applied to the quadrupole electrode, will be different from the intensity used in the operation of the configuration shown in FIG. 3a.

[0068] According to the configuration exemplified in FIG. 3a, it should be noted that when the quadrupoles are subsequently deactivated, the detector plane is instead conjugated to the back focal plane (6) of the objective lens system (2), as indicated by the dotted extrapolated projection lines (11a, 11b). Thus, the detector can record the sample image or diffraction pattern, respectively, by simply activating and deactivating the electrostatic quadrupoles (13a, 13b) without any other optical adjustments. Advantageously, the image of the sample can be moved to the edge of the detector's field of view by a slight shift of the incident electron beam (9) without significant decay of the diffraction pattern. This allows the user to record a double-exposure composite image by acquiring multiple exposures with the quadrupoles activated and deactivated, if desired.

[0069] FIG. 3b illustrates the light path of a field light electron when the quadrupoles (13a, 13b) are simultaneously activated or when only the quadrupole (13b) is equally activated. Since the first quadrupole (13a) is located in the plane where the field light focuses, the activation of this quadrupole does not affect the trajectory of the field light (5) as it passes through this plane. Therefore, the path of the field light (5) remains the same as the corresponding path shown in FIG. 1a between the two quadrupoles. When the field light (5) meets the second quadrupole (13b), it splits into secondary light rays (5a, 5b) as shown. Since the various secondary light rays (5a, 5b) do not converge to a single focus on the detector plane (8), a diffraction pattern image is not recorded by the detector. Therefore, to summarize, FIG. 3a shows that a focused image of the sample is present on the detector surface, and FIG. 3b provides an indication of the magnification associated with the image. As mentioned above, when the two quadrupoles are deactivated, the light path returns to that shown in FIG. 1a, at which time a diffraction pattern image can be recorded.

[0070] Referring further to FIGS. 3a and 3b, it should be noted that when only the quadrupole (13a) is activated while the quadrupole (13b) remains inactive, the detector plane (8) is conjugated to the diffraction plane (6) because the quadrupole (13a) is positioned at the back focal plane (i.e., the "diffraction plane") (6) of the lens system (2) (see the light paths labeled 11a, 11b and 4ab in FIG. 3a). In this situation, the detector will record a focused diffraction pattern.

[0071] FIG. 4 is a schematic illustration of a field ray path passing through a second modified version of the substage assembly of FIG. 1a, modified compared to the modified version shown in FIG. 3a and 3b by replacing the first electrostatic quadrupole (i.e., quadrupole (13a)) with a stigmatizer (14a) (e.g., electromagnetic quadrupole), so that the stigmatizer (14a) is positioned at the back focal plane of the objective lens system (2) and remains always active. As shown in FIG. 4, the operation of the electrostatic quadrupole (13b) can be controlled so that the axial rays (4) are ultimately focused on the detector plane (8), thereby projecting an image of the sample onto the detector plane. Since the basic hardware configuration remains unchanged from that shown in FIGS. 3a and 3b except that the first quadrupole is replaced by a stigmatizer (14a), deactivation of the single capacitive quadrupole (13b), as indicated by the graphic projection lines (12a, 12b), causes the detector plane (8) to be conjugated once again with the back focal plane (6) of the objective lens system (2). Thus, the activation and deactivation of the single capacitive quadrupole (13b) can be used to switch between recording the diffraction pattern and recording the sample image, and vice versa.

[0072] FIG. 5a is an image of a sample that can be generated by an electron microscope substage assembly in which the optical components are arranged as in FIG. 4 and both the stigmatizer (14a) and the quadrupole component (13b) are activated. FIG. 5b is a diffraction pattern of a sample that can be obtained using the same system and the same sample as imaged in FIG. 5a, but with the quadrupole (13b) deactivated and the stigmatizer kept activated. Thus, using the configuration shown in FIG. 4, it is possible to rapidly switch between diffraction and sample imaging by activating and deactivating only one optical component, namely the quadrupole (13b) of the selected aperture plane (7). Multiple exposures in which the diffraction pattern and the sample image overlap can be obtained by switching between the two modes during a single camera exposure of the detector. In an alternative but less preferred embodiment, a single stigmat (14a) may be replaced with two stigmats located downstream of the back focal plane (6), wherein the combined action of the pair of stigmats performs the same role and has the same effect as the single stigmat (14a) of the back focal plane. However, this alternative configuration was found to cause some image distortion and was therefore less preferred.

[0073] FIG. 6a is a part of a set of optical components (40) within the beam delivery portion of an electron microscope column (not shown) of a transmission electron microscope (TEM) configured and operated in a manner known to deliver an electron beam collimated onto a sample. FIG. 6b is a schematic illustration of a modified version of the set of optical components (40) of FIG. 6a, the modification being in accordance with the present teaching. The Z-axis shown in FIG. 6a and 6b corresponds to the axis (110) shown in FIG. 2, as well as the column axis (10) shown in FIG. 1, 3a, 3b and 4. The sample surface (49) on which the sample is placed is shown to the right of FIG. 6a and 6b, respectively.

[0074] An electron source (not shown) and at least a focusing lens (not shown) and an intermediate lens (not shown) provide an electron stream containing multiple rays to the optical components of an illumination column. These are located on the left side of the left side of FIGS. 6a and 6b, respectively. After collimation, the rays are focused by one or more lenses not shown located on the left side of the leftmost part of FIGS. 6a and 6b, respectively. The leftmost part of each of these figures is the focal point (59) of the lens not shown. FIGS. 6a illustrates the path of a single ray (37). FIGS. 6b shows the path of the same ray (37), as well as the path of separate sub-rays (37a, 37b) to which the ray (37) can be split according to the present teaching.

[0075] A known set of optical components (40) includes a plurality of lenses, the positions of which are denoted as L1, L2, L3, …, L8 in both FIG. 6a and FIG. 6b. The lenses themselves are not specifically illustrated in either FIG. 6a or FIG. 6b. However, magnetic field strength plots (41, 42, 43, 44, 45, 46, 47, 48) graphically represent the magnetic field strength at the corresponding positions of each lens. Four of the lenses, specifically lenses (L3, L4, L5, L6), are contained within a known probe aberration corrector (51). The inset in FIG. 6a is an enlarged version of a circular area (54) near the sample surface (49), showing that through beam manipulation of the various optical components (40), not only the light ray (37) but also all other light rays and electrons passing through the focal point (52) are introduced onto the sample as a circular collimated beam parallel to the Z-axis. As shown in Fig. 6a, the optical components configured in this way serve the purpose of delivering a collimated beam to a sample for TEM research.

[0076] The known lens system (51) is a sextupole type probe Cs-corrector, where Cs is the spherical aberration coefficient. The main components of the probe aberration corrector (51) are magnetic sextupole elements (52, 53). The sextupole elements generate a strong sextupole field used to generate a negative Cs. For parasitic aberration correction (i.e., correction due to mechanical error), these sextupole elements (52, 53) also generate relatively weak bipolar and quadrupole fields, and these weak fields are placed in FIGS. 6a and 6b. In relation to the following discussion, these quadrupole fields do not need to be switched, that is, the excitation conditions are the same in both FIGS. 6a and 6b.

[0077] FIG. 6b is a schematic illustration of a modified version of the set of optical components illustrated in FIG. 6a. According to the present teaching, the set of optical components (40b) is modified for the set of components (40) by including an additional quadrupole element (55) in the beam path position adjacent to the L1 lens position and immediately downstream thereof. The quadrupole element (55) is configured to split the light beam (30) into secondary beams (30a, 30b) when operated, which reconverge into a finely focused, sub-angstrom-sized probe beam on the sample plane when actuated by the existing downstream lenses (L2, L3, L4, …, L8) and quadrupole (52, 53). Furthermore, the inventors have found that the light path modification illustrated in FIG. 6b does not interfere with the proper functioning of the aberration corrector (51). Accordingly, by activating a single quadrupole optical component (55), the operating mode of the electron microscope system can be rapidly switched to an atomic resolution STEM, STEM-EDS, or STEM-EELS mode. Deactivating the quadrupole (55) switches the operating mode back to the TEM mode. Additionally, the operation of the microscope can be rapidly switched between different operating modes as desired.

[0078] FIG. 7a is a schematic illustration of a portion of a set of substage components of a transmission electron beam microscope provided in a configuration including a laser phase plate for image contrast enhancement. FIG. 7a also shows the light paths of a representative field ray (79) and a representative axial ray (78). The substage components illustrated in FIG. 7a are positioned in the region between the sample plane (71) and the diffraction plane (72). The components of the substage assembly of FIG. 7a include an objective lens system (73), a first transfer lens system (74) positioned on or near the first intermediate image plane of the objective lens system, and a second transfer lens system (75) positioned on or near the intermediate diffraction plane where the field ray (79) converges. It should be noted that the drawings are highly schematic and that each component described as a “lens” may actually comprise a multi-component lens system or lens assembly.

[0079] In addition to the components mentioned above, the substage includes a laser phase plate (77) that is also positioned at or near the intermediate diffraction plane where the second transfer lens (75) is located. Generally, the laser phase plate is a photonic optical cavity positioned in the path of the electron beam. A laser beam emitted from a laser (not shown) is further amplified within the laser cavity and forms a precise focus that matches a selected specific electron beam path. A ponderomotive force applied to electrons by the energy of the photonic standing wave generated from the laser beam within the cavity induces a phase shift in some electrons. The interference between the phase-shifted electrons and the non-phase-shifted electrons is utilized to enhance contrast in the TEM image of the sample.

[0080] One of the main difficulties in using a phase plate is aligning the phase plate with the electron beam, which requires precise control over the position and orientation of the phase plate. The inventors have discovered that, as illustrated in FIG. 7b, by incorporating a switchable electrostatic quadrupole element (76) adjacent to the first transfer lens system (74) in the first intermediate image plane of the objective lens system, laser interference fringes can be visualized in the image plane. Thus, alignment adjustments for the laser beam can be performed, and at the same time, the pattern of the interference fringes can be detected and displayed.

[0081] Referring to both FIG. 7a and 7b, it can be observed that the axial ray (78) remains focused on the diffraction plane (72) regardless of whether the quadrupole (76) is present, and if the quadrupole is present, regardless of whether the quadrupole is active. The reason the axial ray path is not affected by the presence or active state of the quadrupole (76) is that the quadrupole is positioned by the objective lens system (73) in the plane where the axial ray (78) is focused. In contrast, when the quadrupole (76) is absent (Fig. 7a) or otherwise deactivated, the field ray (79) is focused on the plane of the laser phase plate (77) on the diffraction plane (75), and this configuration is referred to herein as the “planar” configuration. In the planar configuration, image contrast is optimized when one of the antinodes of the laser focus coincides with the focus of the field ray (79).

[0082] When the quadrupole (76) is present and activated, each field ray (79) is split into a first ray (79a) and a second ray (79b). Due to this splitting, the field ray (79b) (dotted line in FIG. 7b) is focused on the upper focal plane (82) by the first transfer lens system (74). At the same time, the field ray (79a) (dashed line) is focused on the lower focal plane (83) by both the first transfer lens system (74) and the second transfer lens system (75). This state is referred to herein as an "out-of-plane" configuration. In an out-of-plane configuration, if a switchable electrostatic quadrupole is configured such that the upper focal plane (82) and the lower focal plane (83) are substantially equidistant from the nominal focal plane (75), as shown in FIG. 7b, the image of the sample will be superimposed with the pattern from the laser as a set of bright and dark bands in the electron microscope image (e.g., see FIG. 8). Under these conditions, it is possible to observe the spatial effects of destructive and constructive laser standing wave interference within the optical cavity on the detector surface conjugated to the image surface. Note that since the electrostatic quadrupole (76) is located on or near the image surface (74), the activation and deactivation of the electrostatic quadrupole do not affect the image of the object but only affect the visibility of the laser fringe superimposed on the image.

[0083] The interference fringe pattern observed in the out-of-plane configuration provides information regarding the relative alignment between the laser beam and the electron beam. The out-of-plane fringe pattern that appears when moving from a well-aligned planar situation to an out-of-plane situation can be used as a reference image to maintain the electron beam in a well-aligned state with the laser beam. The transition between the planar imaging mode and the out-of-plane mode showing the interference fringe can be performed using a high-speed response switching device such as an electrostatic quadrupole (76). Through this procedure, the analyst can rapidly alternate between observing the fringe and observing the sample image to obtain optimal image contrast and correlate the image contrast with the fringe pattern in near real-time.

[0084] Likewise, the ability to rapidly switch between imaging mode and diffraction mode using a high-speed response switching device as described herein may be necessary when microscopically examining a sample that moves, degrades, decomposes, reacts, sublimates, or otherwise changes during the irradiation process (whether intentionally or unintentionally). In such cases, it may be advantageous or even necessary to switch modes at a repetition rate equal to or faster than the frame acquisition rate of the camera detector or the scan repetition rate of the scanning system. By making the switching time shorter than the camera frame time, double exposure or multiple exposures can be created. For example, FIG. 9a is a composite image acquired by scanning a sample using a STEM device, which is an image of a sample comprising a plurality of diffraction image bands (92) arranged alternately with a sample image band (91), wherein the switching between sample imaging and diffraction imaging is controlled by applying a 50 Hz voltage waveform to an electrostatic quadrupole switching device as shown in FIG. 9c. Each set of bands (91, 92) can be separately compared and / or correlated to monitor changes in the sample (if any) or changes in microscope performance (if any) throughout the data acquisition process. FIG. 9b is a composite image obtained by assembling the STEM image bands (91) into a single image (93) of the sample and assembling the diffraction image bands (92) into a launchgram (94). The shape, pattern, and symmetry observed in the launchgram indicate the presence and nature of lens aberrations, if any. By analyzing these patterns, it is possible to detect possible image distortions in the sample image (93) and, if necessary, adjust the microscope to correct the aberrations causing the distortion.

[0085] FIGS. 11, 12, and 13a depict an exemplary bifocal beamforming device described in U.S. Publication 2021 / 0302333-A1, which may be modified for use as an electrostatic multipole in a device according to the present teaching (e.g., FIG. 13b). FIG. 11 shows a cross-sectional view of an exemplary embodiment of an exemplary bifocal beamforming device (1100) that may be manufactured by the same method used to manufacture a general microelectromechanical system (MEMS). Specifically, FIG. 11 illustrates a cross-sectional view of a MEMS-like device (1100) configured to split a plurality of electron streams (1102) into a first electron beam (1104) and a second electron beam (1106) and to generate an electromagnetic field pattern that applies at least a quadrupole lens effect to at least the second electron beam (1106). At least the quadrupole lens effect causes the first electron beam (1104) and the second electron beam (1106) to have different focal characteristics. For example, the quadrupole lens effect can apply a positive lens effect to one meridian (e.g., the yz plane) and a negative lens effect to a perpendicular meridian (e.g., the xz plane), thereby causing different changes in focal characteristics in each of the two meridians. FIG. 11 illustrates a cross-section of a MEMS device (1100) comprising a surface layer (1108), an electrode layer (1110), and an optional shielding layer (1112). In FIG. 11, the surface layer (1108) is shown to comprise a thin material (e.g., a foil) upon which electrons (1102) are incident. In another embodiment, the surface layer (1108) does not correspond to a separate component layer, but instead may correspond to the upper surface of one or more components of the MEMS device (1100) upon which electrons (1102) are incident.

[0086] Referring again to FIG. 11, the surface layer (1108) defines a first inlet (1114) to a first opening (1116) and a second inlet (1118) to a second opening (1120). The first inlet (1114) allows a first portion of electrons (1102) (i.e., a first electron beam (1104)) to enter the first opening (1116) and pass through the MEMS device (1100). Likewise, the second inlet (1118) allows a second portion of electrons (1102) (i.e., a second electron beam (1106)) to enter the second opening (1120) and pass through the MEMS device (1100). The surface layer (1108) inhibits the ability of the remainder of the electrons (1102) to pass into and / or through the MEMS device (1100).

[0087] The electrode layer (1110) comprises a plurality of microelectrodes, which are shaped, positioned, or otherwise configured such that when a corresponding voltage is applied to one or more electrodes, one or more electrodes generate an electromagnetic field pattern that applies a lens effect to one or both of the first electron beam (1104) and the second electron beam (1106). The lens effect is to modify the focal characteristics of the two beams so that they have different corresponding focal characteristics. One or more of the magnitude of the voltage applied to the electrodes, the shape of the electrodes, and the thickness (L) of the electrodes may be modified to change the intensity of the generated electromagnetic field pattern. According to the present disclosure, the electrodes within the electrode layer (1110) are configured to generate at least a quadrupole electromagnetic field distribution that imparts at least a quadrupole lensing effect to the second electron beam (1106), wherein the lensing effect may be implemented, for example, by a double-lens, quadrupole, six-lens, eight-lens, etc. In some embodiments, the electromagnetic field pattern may also apply a dipole to one or both of the first electron beam (1104) and the second electron beam (1106). Such a dipole may cause at least one of the electron beams to be deflected in a direction not parallel to the emission axis z. FIG. 11 also illustrates a MEMS device (1100) comprising an optional shielding layer (1112) opposite the surface layer (1108), the shielding layer being configured to at least partially insulate the first electron beam (1104) from at least a quadrupole lens effect applied to the second electron beam (1106).

[0088] FIG. 12 shows a top-down schematic diagram of an example of a MEMS capacitive multipole embodiment (1200) comprising four electrodes. FIG. 12 and 13 illustrate the first inlet (1114) and the second inlet (1118), defined by the surface layer (1108), with solid lines. Additionally, FIG. 12 and 13 illustrate the components of the electrode layer (1110) with dashed lines. Those skilled in the art will recognize that the dashed lines do not necessarily represent the exact shape, but rather represent the general outline of the electrodes within the electrode layer (1110). FIG. 12 shows the radius R of the first inlet (1114). A1 The radius R of the first opening (1116) defined at least partially by this electrode (1202) E1 It shows that it is smaller. In an embodiment of an exemplary MEMS device (1200), the radius R A1 can be 10 μm or around it, and radius R E1 The radius may be 14 μm or greater. In FIG. 12, the radius R of the second inlet (1118) A2 Radius R of the second opening (1120) defined at least partially by the electrodes (1202, 1204, 1206, 1208) E2 It is shown that it is smaller. However, in other embodiments, the radius R E1 and radius R A1 , and / or radius R E2 and radius R A2 One or both of them may be the same. An exemplary embodiment (1200) has a radius R A1 and radius R A2 It is additionally depicted as being identical and / or approximately identical, but this is not required for all embodiments. The first entrance (1114) and the second entrance (1118) are separated by a distance D.

[0089] During use of the exemplary MEMS device (1200), a voltage may be applied to one or more of the electrodes (1202-1208) so that the electrodes generate an electromagnetic field that applies at least a quadrupole lens effect to the second electron beam. In some embodiments, one or more electrodes may be grounded. For example, the exemplary MEMS device (1200) may generate an electromagnetic field that applies at least a quadrupole lens effect to the second electron beam when a first voltage V1 is applied to electrode (1204), a second voltage V2 is applied to electrode (1208), and electrodes (1202, 1206) are grounded. In various embodiments, V1 and V2 may each be greater than -20V and less than +20V, but larger voltages may also be used.

[0090] FIG. 13a shows a top-down schematic diagram of an exemplary embodiment (1300) of a MEMS capacitive multipole device comprising seven electrodes. FIG. 13a shows the radius R of the first inlet (1114). A1 The radius R of the first opening, which is at least partially defined by this electrode (1302, 1304, 1306, 1308). E1 It shows that it is smaller than. FIG. 13a illustrates a first inlet (1114) as an axial opening through which a plurality of electron emission axes (1310) pass. Also in FIG. 13a, the radius R of a second inlet (1118) A2 The radius R of the second opening, which is at least partially defined by the electrodes (1306, 1312, 1314, 1316). E2 It is shown that it is smaller than. However, in another embodiment, the radius R E1 and radius R A1 , and / or radius R E2 and radius R A2 One or both of them may be the same.

[0091] During use of the exemplary MEMS device (1300), voltage may be applied to one or more of the electrodes (1302-1308, 1312-1316) so that the electrodes generate an electromagnetic field that applies at least a quadrupole lens effect to the second electron beam. In some embodiments, one or more electrodes may be grounded. For example, the exemplary MEMS device (1300) may generate an electromagnetic field that applies at least a quadrupole lens effect to the second electron beam when a first set of voltages with values ​​between -20V and +20V is applied to the electrodes (1304, 1308, 1312, 1316), a second set of voltages with values ​​between -5V and +5V is applied to the electrodes (1302, 1314), and the electrode (1306) is grounded.

[0092] The known bifocal beamforming systems (1100, 1200, 1300) mentioned above are designed to separate a single charged particle beam into separate charged particle beams and to focus and / or form the two separated beams independently. However, many charged particle beam systems described herein do not require such complex beam separation and beamforming operations. Nevertheless, the structure of a known bifocal beamforming system can be simplified for use as an electrostatic quadrupole device as previously described herein. For example, FIG. 13b illustrates an exemplary electrostatic quadrupole (1350) comprising a subset of the components of a bifocal beam system (1300). Specifically, since it may not be necessary to split the charged particle beam into two separate beams, the second inlet (1118) and the corresponding second opening can be removed from the structure. The removal of the second opening and the second inlet also eliminates the need for the electrodes (1312, 1314, 1316) exemplified as components of the bifocal beam forming device (1300) in FIG. 13a. The resulting simplified device (1350) (Fig. 13b) includes only the inlet (1114), and its circular shape is defined by the shape of the surrounding four electrodes (1302, 1304, 1306, 1308).

[0093] A person skilled in the art will understand that the dashed lines in FIG. 12, 13a and 13b represent exemplary configurations of electrodes, and that through experimentation, a number of electrode configurations (e.g., electrode size, electrode shape, number of electrodes, electrode arrangement, combination of voltages applied to the electrodes, etc.) may be provided. This causes the electrodes to generate an electromagnetic field that applies at least a quadrupole lens effect to a beam of charged particles. As just one example, a person skilled in the art will recognize that applying a first potential V1 to opposing electrodes (1302, 1306) of an electrostatic quadrupole device (1350) and simultaneously applying a second different potential V2 to electrodes (1304, 1308) may correspond to the "activation" of the device (1350) capable of generating a quadrupole lens effect on a beam of charged particles passing through an aperture. Additionally, according to this example, applying substantially the same potential to all four electrodes (1302, 1304, 1306, 1308) may constitute "deactivation" of the device (1350). It should be noted that, as used herein, "application" of potential to the electrode may include grounding the electrode and / or allowing the potential of the electrode to "float."

[0094] FIG. 10 illustrates a block diagram of a controller (1000) and a power supply (1600) for a microscope system according to a specific embodiment of the present disclosure. As illustrated, the controller (1000) includes a processor (1002) that is communicably coupled to memory (1504). The processor (1002) may include one processing unit or a number of processing units. Non-limiting examples of the processor (1002) include a Field-Programmable Gate Array (FPGA), an Application-Specific Integrated Circuit (ASIC), a microprocessor, or a combination thereof. The processor (1002) may execute instructions (1510) stored in memory (1504) to perform operations such as operating, processing, scanning, and operations related to the various methods described herein. In some examples, instructions (1510) may include processor-specific instructions generated by a compiler or interpreter from code written in a suitable computer programming language such as C, C++, C#, Python, or Java.

[0095] The memory (1504) may include one memory device or multiple memory devices. The memory (1504) may be non-volatile and may include any type of memory device that retains stored information when the power is turned off. Non-limiting examples of the memory (1504) include electrically eraseable and programmable read-only memory (EEPROM), flash memory, or any other type of non-volatile memory. At least a portion of the memory (1504) may include a non-transient computer-readable medium tangibly embodied so that the processor (1002) can read instructions (1510) via a bus (1006). The bus (1006) may be a communication and / or power bus that enables the processor (1002) to communicate with the memory (1504). The non-transient computer-readable medium may include an electronic, optical, magnetic, or other storage device capable of providing instructions (1510) or other program code to the processor (1502). Non-limiting examples of non-transient computer-readable media include magnetic disks, memory chips, RAM, ASICs, or any other media in which a computer processor can read instructions (1510).

[0096] The memory (1504) may further include information regarding parameters (1512) (e.g., calibration, tuning, stage position, beam intensity, etc.), a beam scan controller (1514) (e.g., scan coordinates, stored images, etc.), detector operation (e.g., detector control, sensitivity, etc.), and an image rendering device (1520). The controller (1000) may receive information regarding operating parameters from a charged particle microscope such as a STEM or TEM. At least some of the information regarding any of the controller components may be stored in advance. The parameters (1512) may include operating parameters related to the electron microscope system, such as the desired energy / primary energy of the electron beam, energy diffusion of the energy loss spectrum, lock-up mechanism, feedback loop, etc.

[0097] Any system described herein may include a controller system (1000) capable of automatically controlling one or more power supplies (1600) to regulate the voltage applied to one or more beam path switching devices discussed herein, such as one or more electrostatic quadrupole elements and / or one or more stigmats, for the purpose of switching the operating mode of a charged particle beam microscope device from a first operating mode to a second operating mode and / or from a second operating mode to a first operating mode. The controller system may be electronically connected to a computer-readable memory (1504) that provides program instructions (1510) to the controller system, and when executed by the controller system, the instructions cause the controller system to provide one or more beam path switching devices with a series of voltage configurations that cause one or more power supplies to repeatedly switch the operating mode of the charged particle beam microscope device between a first operating mode and a second operating mode.

[0098] The controller system may also electronically communicate with one or more other components of the charged particle beam microscope device, such as a sample stage on which a sample of interest is mounted and which can be moved by one or more actuators. In such cases, the controller system may be configured to cause one or more power supplies to transmit electronic and / or electrical signals to one or more actuators in cooperation with the repetitive switching of the aforementioned operating modes to move the sample stage. The controller system may be instructed to trigger such movement of the sample stage by the execution of program instructions received from computer-readable memory.

[0099] The controller system may also electronically communicate with one or more detector systems of the charged particle beam microscope device and may be operable to control the timing of data acquisition by one or more detector systems under the control of program instructions received from computer-readable memory. For example, when the program instructions (1510) are executed by the processor (1002) of the controller system (1000), the controller system may control one or more detector systems to acquire data at a specific time coordinated with the transition of the operating mode of the charged particle beam microscope device from a first operating mode to a second operating mode and / or from a second operating mode to a first operating mode, as described herein.

[0100] Although the present invention has been described according to the illustrated embodiments, those skilled in the art will readily recognize that variations may be made to the embodiments and that such variations are within the scope of the present invention. Accordingly, many modifications may be made by those skilled in the art without departing from the scope of the appended claims. For example, various embodiments of the present invention may be described by one or more of the following provisions:

[0101] Clause 1. Charged particle beam columns of a transmission electron microscope (TEM) or scanning transmission microscope (STEM) system including the following:

[0102] It includes a switchable multipole element configured to generate a quadrupole when activated and configured to alternately activate and deactivate, and positioned near a first lens system of a probe beam delivery system, wherein the first lens system is configured to receive a diverging beam from a focusing lens system of an electron microscope, and

[0103] Here, the activation of the switchable multipole element allows a focused charged particle probe beam to be delivered from the charged particle beam delivery system onto the sample, and the deactivation of the switchable multipole element allows a collimated charged particle beam to be delivered from the charged particle beam delivery system onto the sample.

[0104] Clause 2. A charged particle beam column as described in Clause 1, comprising the following:

[0105] A six-pole type spherical aberration corrector comprising two magnetic six-pole elements disposed between the switchable multipole element and the sample and generating negative spherical aberration correction, wherein, when the switchable multipole element is activated, a circular probe beam of sub-angstrom diameter is delivered to a selected point on the sample.

[0106] Clause 3. An improved substage optical system for a transmission electron microscope (TEM) or scanning transmission electron microscope (STEM) comprising: an objective lens system; a first transfer lens system positioned at the rear focal plane of the objective lens system; a second transfer lens system positioned at the intermediate diffraction plane formed by the objective lens system and the first transfer lens system; a laser phase plate positioned near the intermediate diffraction plane; and a laser that directs a laser beam onto the laser phase plate; wherein the improvements include:

[0107] A switchable multipole element configured to generate a quadruple theater when activated, positioned near the objective lens image plane, and configured to be repeatedly activated and deactivated.

[0108] Clause 4. An improved substage optical system of Clause 3, wherein the switchable multipole element is a switchable capacitive multipole element having a switching time of 100 milliseconds or less, or alternatively 10 milliseconds or less, or alternatively 1 millisecond or less, or alternatively 500 microseconds or less, or alternatively 10 microseconds or less, or alternatively 1 microsecond or less, or alternatively 500 nanoseconds or less, or alternatively 50 nanoseconds or less.

[0109] Clause 5. As an improved substage optical system of Clause 3,

[0110] An improved substage optical system in which the above-described switchable multipole element is configured to allow a detector to receive an image pattern that reflects the effect of laser phase plate operation on the spatial change of transmitted electron intensity when activated.

[0111] Clause 6. As a charged-particle beam (CPB) system, a charged-particle beam (CPB) microscope comprising the following:

[0112] Charged particle beam source; Charged particle beam source;

[0113] A CPB column configured to transmit a charged particle beam from a charged particle beam source to a sample;

[0114] A CPB projection assembly comprising a transfer optical system that transmits charged particles transmitted through the sample, emitted by the sample, or scattered by the sample to a detector; and

[0115] As a switchable multipole element that is switchable between an active state and an inactive state, configured to generate a quadruplet when activated, and placed within either a CPB column or a CPB projection assembly:

[0116] Activating the above-mentioned switchable multipole element enables the CPB microscope to generate or be able to generate one or more images according to a first imaging mode;

[0117] Deactivating the above-mentioned switchable multipole element enables the CPB microscope to generate one or more images according to the second imaging mode.

[0118] Clause 7. A CPB microscope as described in Clause 6, wherein the switchable multipole element is a switchable electrostatic multipole element having a switching time of 100 milliseconds or less, or alternatively 10 milliseconds or less, or alternatively 1 millisecond or less, or alternatively 500 microseconds or less, or alternatively 10 microseconds or less, or alternatively 1 microsecond or less, or alternatively 500 nanoseconds or less, or alternatively 50 nanoseconds or less.

Claims

Claim 1 A method for rapidly switching between a first imaging or data acquisition mode and a second imaging or data acquisition mode within a charged particle beam (CPB) microscope, comprising the step of activating a switchable multipole element of the CPB microscope, wherein the switchable multipole element is configured to generate a quadruplet field when activated, and the activation enables the CPB microscope to generate a first set of one or more images or data sets containing information about a sample according to the first imaging or data acquisition mode, or to generate said first set; and comprising the step of deactivating the switchable multipole element, wherein the deactivation enables the CPB microscope to generate a second set of one or more images or data sets containing information about the sample according to the second imaging or data acquisition mode, or to generate said second set. Claim 2 A method described in claim 1, wherein the switchable multipole element is a switchable electrostatic multipole element. Claim 3 A method described in claim 2, wherein the switching time of the switchable capacitive multipole element is 100 milliseconds or less, or alternatively 10 milliseconds or less, or alternatively 1 millisecond or less, or alternatively 500 microseconds or less, or alternatively 10 microseconds or less, or alternatively 1 microsecond or less, or alternatively 500 nanoseconds or less, or alternatively 50 nanoseconds or less. Claim 4 A method described in claim 1, wherein the switchable multipole element is repeatedly activated and deactivated within a single detector frame time according to a duty cycle, each activation causes the CPB microscope to generate a construction image according to a first imaging mode, each deactivation causes the CPB microscope to generate a construction image according to a second imaging mode, and a multi-exposure composite image is generated by the superposition of the construction images. Claim 5 A method described in claim 4, wherein the switchable multipole element is placed within an image projection system of the CPB microscope that projects a diffraction pattern onto a detector when the switchable multipole element is deactivated. Claim 6 A method described in any one of claims 1 to 5, wherein the image projection system further comprises an active stigmat disposed on the rear focal plane of an objective lens, and each activation and deactivation of a switchable multipole element comprises each activation and deactivation of a switchable multipole element located on a selected aperture plane of an objective lens system within the image projection system, wherein each activation corresponds to the generation of an image of the sample and each deactivation corresponds to the generation of a diffraction pattern from the sample. Claim 7 A method described in claim 6, wherein the switchable multipole element is a switchable capacitive multipole element, and the switching time of the switchable capacitive multipole element is 100 milliseconds or less, or alternatively 10 milliseconds or less, or alternatively 1 millisecond or less, or alternatively 500 microseconds or less, or alternatively 10 microseconds or less, or alternatively 1 microsecond or less, or alternatively 500 nanoseconds or less, or alternatively 50 nanoseconds or less. Claim 8 A method described in claim 5, wherein the image projection system further comprises a pair of active stigmats disposed between a back focal plane and a projection lens, wherein the pair of active stigmats have the same effect as a single stigmat disposed at the back focal plane of an objective lens with respect to a charged particle beam path in the image projection, and each activation and deactivation of the switchable multipole element comprises each activating and deactivating a switchable multipole element located at or near the intermediate image plane of the image projection system, wherein each activation corresponds to the generation of an image of a sample and each deactivation corresponds to the generation of an electron diffraction pattern from the sample. Claim 9 A method described in claim 5, wherein the image projection system comprises a laser phase plate disposed on a diffraction plane conjugated to the rear focal plane of an objective lens toward which a laser beam is directed, and each activation and deactivation comprises activating and deactivating a switchable multipole element located on or near the image plane of the objective lens of the image projection system, and each activation enables the superimposed image of the sample and the laser interference fringe to be acquired by a detector. Claim 10 A method described in claim 9, wherein the switchable multipole element is a switchable capacitive multipole element, and the switching time of the capacitive multipole element is 100 milliseconds or less, or alternatively 10 milliseconds or less, or alternatively 1 millisecond or less, or alternatively 500 microseconds or less, or alternatively 10 microseconds or less, or alternatively 1 microsecond or less, or alternatively 500 nanoseconds or less, or alternatively 50 nanoseconds or less. Claim 11 A method described in any one of claims 1 to 5, wherein the switchable multipole element is disposed within a CPB microscope column that directs a charged particle beam toward a sample. Claim 12 A method described in claim 11, wherein the switchable multipole element is positioned between the focal point of a beam condenser lens system of the CPB microscope column and an aberration correction system of the CPB microscope column, wherein activation of the switchable multipole element causes the CPB microscope column to operate so that a focused probe beam is delivered to a sample, enabling a scanning transmission microscope (STEM) operation mode, and deactivation of the switchable multipole element causes the CPB microscope column to operate so that a collimated beam is delivered to a sample, enabling a transmission electron microscope (TEM) operation mode. Claim 13 A method described in claim 12, wherein the aberration correction system comprises a six-pole type spherical aberration corrector comprising two active magnetic six-pole elements that generate negative spherical aberration correction, and when the switchable multipole elements are activated, a focused circular probe beam is delivered to a selected point on a sample. Claim 14 A method described in claim 13, wherein the probe beam is focused into a spot of sub-angstrom diameter. Claim 15 A method described in claim 1, wherein the CPB microscope is a scanning transmission electron microscope, the first imaging mode is a sample imaging mode, the second imaging mode is an electron diffraction mode, and the switchable multipole element is repeatedly activated and deactivated while scanning an electron beam across the surface of the sample. Claim 16 A charged particle beam (CPB) microscope system comprising: a charged particle beam source; a CPB column configured to deliver a charged particle beam from the charged particle beam source to a sample; an optical assembly comprising a delivery optical system configured to deliver charged particles transmitted through the sample or scattered by the sample to a detector; and a switchable multipole element member included in either the CPB column or the optical assembly, wherein the switchable multipole element is configured to form a quadrupole field when activated, and further comprises a CPB microscope system configured to satisfy the following: The activation of the switchable multipole element enables the CPB microscope to generate a first set consisting of one or more images or data sets containing information about a sample according to a first imaging or data acquisition mode, or makes this possible. Deactivation of the switchable multipole element enables the CPB microscope to generate a second set consisting of one or more images or data sets containing information about the sample according to a second imaging or data acquisition mode. Claim 17 A charged particle beam (CPB) microscope system described in claim 16, further comprising an image rendering device configured to render a multi-exposure composite image by superimposing one or more images of one or more of a first set of images or data sets and one or more images of one or more of a second set of images or data sets. Claim 18 A CPB microscope according to claim 16, wherein the switchable multipole element is a switchable electrostatic multipole element, and the switching time of the switchable electrostatic multipole element is 100 milliseconds or less, or alternatively 10 milliseconds or less, or alternatively 1 millisecond or less, or alternatively 500 microseconds or less, or alternatively 10 microseconds or less, or alternatively 1 microsecond or less, or alternatively 500 nanoseconds or less, or alternatively 50 nanoseconds or less. Claim 19 In a transmission electron microscope (TEM) system, an image projection system comprising the following configuration: the image projection system comprising, wherein the image projection system comprises: An objective lens system configured to receive electron beams from a sample and having a back focal plane; A projection lens system positioned between the objective lens system and the detector; and It includes a first switchable multipole element configured to generate a quadruple theater when activated, located on a selected aperture plane of the objective lens system, and configured to be alternately activated and deactivated, A TEM system in which the activation of the first switchable multipole element causes an image of the sample to be projected onto the detector, and the deactivation of the first switchable multipole element causes a diffraction pattern of the sample to be projected onto the detector. Claim 20 A TEM system described in claim 19, wherein the switchable multipole element is a switchable electrostatic multipole element, and the switching time of the first switchable electrostatic multipole element is 100 milliseconds or less, or alternatively 10 milliseconds or less, or alternatively 1 millisecond or less, or alternatively 500 microseconds or less, or alternatively 10 microseconds or less, or alternatively 1 microsecond or less, or alternatively 500 nanoseconds or less, or alternatively 50 nanoseconds or less. Claim 21 A TEM system described in claim 19, wherein the image projection system further comprises a second switchable multipole element configured to generate a quadruplet field when activated, located on or near the intermediate image plane of the objective lens system, and configured to be alternately activated and deactivated, wherein the simultaneous activation of the first and second switchable multipole elements causes an image of a focused sample to be projected onto a detector, and the simultaneous deactivation of the first and second switchable multipole elements causes a diffraction pattern of the sample to be projected onto a detector. Claim 22 A TEM system described in claim 21, wherein the second switchable multipole element is a switchable capacitive multipole element, and the switching time of the switchable capacitive multipole element is 100 milliseconds or less, or alternatively 10 milliseconds or less, or alternatively 1 millisecond or less, or alternatively 500 microseconds or less, or alternatively 10 microseconds or less, or alternatively 1 microsecond or less, or alternatively 500 nanoseconds or less, or alternatively 50 nanoseconds or less.

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