Method of operating charged particle microscope system including beam deflector and associated system

Abstract

The disclosure relates to a method of operating a charged particle microscope system including a beam deflector and an associated system. In one example, a method includes adjusting one or more optical elements such that a deflector plane of a beam deflector is conjugated to a diffraction plane, and recording a diffracted beam pattern at the diffraction plane. In another example, a method includes directing a charged particle beam to a sample, transitioning a beam blanker between a blanked state and an unblanked state, and recording a beam pattern by a detector. The beam pattern includes one or more beam pattern features that are substantially stationary in the detector plane when the beam blanker transitions between an unblanked state and a blanked state. In another example, a CPM system includes a charged particle source, a beam deflector at a deflector plane, and a detector. The CPM system is configured such that the charged particle beam exhibits a beam intersection at the deflector plane, and such that the deflector plane is imaged onto the detector.

Description

Technical Field

[0001] This disclosure relates generally to methods of operating a charged particle microscope including a beam deflector, and more specifically to methods of configuring a transmission electron microscope for use in conjunction with a beam deflector in electron diffraction experiments. Background Technology

[0002] Charged particle microscopy is a well-known and increasingly important technique for imaging microscopic objects, particularly in the form of electron microscopy. Basic types of electron microscopes are practically used in various instrument types such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), and scanning transmission electron microscopy (STEM), as well as various subtypes.

[0003] In SEM, irradiation of the sample by a scanning electron beam promotes the emission of "auxiliary" radiation from the sample, such as secondary electrons, backscattered electrons, X-rays, and cathodoluminescence (infrared, visible, and / or ultraviolet photons). One or more components of this emitted radiation are then detected and used for image accumulation purposes.

[0004] As an alternative to using electrons as the illumination beam, charged particle microscopy can also be performed using other types of charged particles. In this regard, the phrase "charged particles" can be understood to encompass, for example, electrons, positive ions (e.g., Ga or He ions), negative ions, protons, and positrons. In addition to imaging and performing (local) surface modifications (e.g., milling, etching, deposition, etc.), charged particle microscopy can also have other functionalities, such as performing spectroscopy, examining diffraction patterns, etc.

[0005] In all cases, charged particle microscopy (CPM) will typically include at least a radiation source (e.g., an electron source or ion gun), a beam guiding system, a sample holder, and a detector.

[0006] Depending on the radiation being detected, detectors can take many different forms. Examples include photodiodes, CMOS detectors, CCD detectors, photovoltaic cells, and X-ray detectors (such as silicon drift detectors and Si(Li) detectors). Generally, a CPM can include several different types of detectors, the selection of which can be invoked in different situations. It is generally desirable for the detector to exhibit a sufficiently wide dynamic range to represent a wide range of incident charged particle signal magnitudes.

[0007] While this disclosure relates in its entirety to the specific context of charged particle microscopy, and more specifically to transmission electron microscopy, such description is not intended to be limiting, and the apparatus and methods disclosed herein can be applied to any suitable context within the scope of this disclosure. Summary of the Invention

[0008] This article discloses methods for operating charged particle microscopy (CPM) systems that include beam deflectors and related systems.

[0009] In a representative example, a method of operating a CPM system includes adjusting one or more optical elements of the CPM system such that a beam deflector is positioned in a deflector plane conjugate to a diffraction plane, at which a beam of charged particles guided to a sample generates a diffraction beam pattern. The method further includes recording the diffraction beam pattern using a detector positioned at the diffraction plane.

[0010] In another representative example, a method of operating a CPM system includes guiding a charged particle beam to a sample, which modulates the charged particle beam to create a beam pattern downstream of the sample. The method further includes transitioning a beam blanker of the CPM system between an unblanked state and a blanked state. The beam blanker is positioned at a deflector plane. When the beam blanker is in the unblanked state, the charged particle beam reaches the sample. When the beam blanker is in the blanked state, the charged particle beam is guided away from the sample. The method further includes recording the beam pattern using a detector positioned at a detector plane conjugate to the deflector plane. The beam pattern includes one or more beam pattern features focused in the detector plane. When the beam blanker transitions between the unblanked state and the blanked state, the one or more beam pattern features are substantially stationary in the detector plane.

[0011] In another representative example, the CPM system includes a charged particle source, a first optical component positioned downstream of the charged particle source, and a beam deflector positioned at a deflector plane downstream of the first optical component. The charged particle source is configured to emit charged particles along an optical axis toward a sample. The beam deflector is configured to selectively deflect the charged particle beam away from the sample. The CPM system further includes a second optical component positioned downstream of the deflector plane; and a detector positioned at a detector plane downstream of the second optical component. The CPM system is configured such that the charged particle beam exhibits beam crossing at the deflector plane, and that the deflector plane is imaged onto the detector.

[0012] The foregoing and other objects, features and advantages of the disclosed technology will become more apparent from the following detailed description with reference to the accompanying drawings. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of a charged particle microscope (CPM) system based on an example.

[0014] Figure 2 It is a schematic representation of the path of a charged particle beam through an example CPM system.

[0015] Figure 3A It is a schematic representation of the path of a charged particle beam and a partially deflected beam through a CPM system in its initial configuration, based on an example.

[0016] Figure 3B It is a schematic representation of the path of a charged particle beam and a partially deflected particle beam through an example CPM system in an intermediate configuration.

[0017] Figure 3C It is a schematic representation of the path of a charged particle beam and a partially deflected particle beam through a CPM system in a conjugate blanking configuration, based on an example.

[0018] Figure 4 This is an example of stripes formed by an electron beam moving across a detector.

[0019] Figure 5A This is an example of a diffraction pattern recorded by a CPM system in its initial configuration.

[0020] Figure 5B This was recorded after the CPM system entered the conjugate blanking configuration. Figure 5A Examples of diffraction patterns.

[0021] Figure 6A This is an example of a diffraction pattern recorded by a CPM system in its initial configuration, based on another example.

[0022] Figure 6B This was recorded after the CPM system entered the conjugate blanking configuration. Figure 6A Examples of diffraction patterns.

[0023] Figure 7 It is a flowchart depicting the method of operating a CPM system according to an example.

[0024] Figure 8 This is a flowchart depicting a method for operating a CPM system based on another example.

[0025] Figure 9 It is a schematic representation of a computing system that can be used to perform one or more methods of this disclosure, based on an example. Detailed Implementation

[0026] This disclosure relates in its entirety to methods for configuring and / or operating a CPM system (such as a TEM) in a manner that reduces and / or eliminates undesired variations in the diffraction pattern when operating a beam deflector to either blank or not blank a beam of charged particles. As described in more detail below, such beam deflectors can be operated by selectively directing a beam of charged particles to intercept blanking structures (such as apertures) before reaching the sample.

[0027] CPM systems can employ beam deflectors for any of a variety of purposes. As an example, when the CPM system is not actively imaging the sample, a beam deflector can selectively redirect the charged particle beam away from the sample to shield sensitive samples from the effects of the charged particle beam. As another example, switching between blanking and unblanking states allows such beam deflectors to transmit the charged particle beam to the sample in the form of controlled-duration pulses. For example, when using sufficiently fast beam deflectors, charged particle beam pulses can be generated on microsecond, nanosecond, or even sub-nanosecond timescales. Recording the signal created by the charged particle pulses passing through the sample (e.g., in the form of a diffraction pattern) can be used for damage mitigation studies and / or time-resolved studies of sample behavior in pump-probe settings.

[0028] Beam deflectors are typically characterized by the transition time used to switch between a fully blanked state and a fully unblanked state. In many examples, blanking or not blanking a charged particle beam causes the diffracted charged particle beam to move within the diffraction plane in which the diffraction pattern is recorded, thereby causing visible fringes of the diffraction pattern during such a time period. In applications where the charged particle beam pulse length is relatively short relative to the characteristic transition time of the beam deflector, such fringes may become increasingly apparent during exposure to capture the recorded diffraction pattern, thus introducing limitations on the accuracy at which the desired diffraction pattern can be recorded.

[0029] Therefore, this disclosure relates to a method for configuring a CPM system such that the features of the diffraction pattern are at least substantially stationary in the diffraction plane in which the diffraction pattern is recorded. As described in more detail below, this can be achieved by positioning the beam deflector in a plane conjugate to the diffraction plane. Examples of methods for implementing such a configuration are described below.

[0030] Exemplary System Figure 1 An example of a CPM system 100 that can be used to perform various aspects of the methods disclosed herein is described. Specifically, Figure 1 An example of a CPM system in the form of a transmission electron microscope (TEM) is shown.

[0031] like Figure 1As shown, the CPM system 100 includes a vacuum housing 102 and an electron source 104 (e.g., a Schottky emitter) positioned within the vacuum housing 102. The electron source 104 generates an electron beam 106 that passes through an illuminator 110, which guides and / or focuses the electron beam 106 onto a portion of the sample 140. The illuminator 110 has an optical axis 108 and may include any of various electrostatic / magnetic lenses, deflectors 112, correctors (such as astigmatism correction devices), etc. The illuminator 110 may also include and / or may be a condenser system.

[0032] exist Figure 1 In the example, sample 140 is held on sample holder 114. As shown, a portion of sample holder 114 extends within housing 102 and is mounted in bracket 116, which can be positioned / moved in multiple degrees of freedom by positioning device (stage) A. For example, bracket 116 can be... Figure 1 The sample 140 may be displaced in the X, Y, and Z directions and / or rotated about a longitudinal axis parallel to the X direction. This movement allows different portions of the sample 140 to be irradiated / imaged / inspected by an electron beam 106 traveling along the optical axis 108. Additionally or alternatively, this movement may allow selected portions of the sample 140 to be machined, for example, by a focused ion beam (not depicted). Additionally or alternatively, in some examples, the electron beam 106 may be scanned relative to the sample 140 by one or more deflectors 112.

[0033] A (focused) electron beam 106 traveling along optical axis 108 can interact with sample 140 in such a way that various types of "stimulated" radiation are emitted from sample 140, including (e.g.) secondary electrons, backscattered electrons, X-rays, and optical radiation (catholuminescence). One or more of these radiation types can be detected by means of sensor 122, which may be, for example, a combined scintillator / photomultiplier tube or EDX (energy-dispersive X-ray spectroscopy) module. In such examples, images can be constructed using essentially the same principles as in SEM. Additionally or alternatively, electrons that pass through sample 140, are emitted from it, and continue to propagate along optical axis 108 (essentially, although generally with some deflection / scattering) can be studied. This transmitted electron flux enters an imaging system (e.g., a combined mirror / projection lens) 124, which may include various electrostatic / magnetic lenses, deflectors, correctors (such as astigmatism correction devices), etc.

[0034] In normal (non-scanning) TEM mode, this imaging system 124 focuses the transmitted electron flux onto a fluorescent screen 126, which can be retracted / retracted relative to the optical axis 108 as needed (as schematically indicated by arrow 126'). The imaging system 124 will form an image (e.g., a diffraction pattern) of at least a portion of the sample 140 on the screen 126, and this can be viewed through an observation port 128 located in a suitable portion of the wall of the housing 102. The retraction mechanism of the screen 126 can be, for example, inherently mechanical and / or electrically powered.

[0035] Additional or alternative land, and as such Figure 1 As shown, the CPM system 100 may include a TEM camera 130. At the TEM camera 130, the electron flux can form a still image (or diffraction pattern), which can be processed by the controller 150 and displayed on a display device (e.g., a flat panel display). When not needed, the TEM camera 130 can be retracted / withdrawn relative to the optical axis 108 (as schematically indicated by arrow 130').

[0036] Additional or alternative land, and as such Figure 1 As shown, the CPM system 100 may include a STEM detector 132. The output from the STEM detector 132 can be recorded as a function of the (X,Y) scan position of the electron beam 106 on the sample 140, and an image can be constructed that is a “mapping” of the output from the STEM detector 132 as a function of (X,Y). In existing tools, the STEM detector 132 may include a single pixel with a diameter of, for example, 20 mm, in contrast to the pixel matrix characteristically present in the TEM camera 130. Again, when not needed, the STEM detector 132 may be retracted / withdrawn relative to the optical axis 108 (as schematically indicated by arrow 232').

[0037] Additional or alternative land, and as such Figure 1 As shown, the CPM system 100 may include a beam splitter device 134, which may include, for example, an EELS module and / or may be an EELS module.

[0038] It should be noted that the order / position of items 130, 132, and 134 is not strict and many possible variations are conceivable. For example, the beam splitter device 134 may also be integrated into the imaging system 124.

[0039] The controller / computer processor 150 is connected to various illustrated components via control lines (buses) 152. This controller 150 provides a variety of functions, such as synchronizing actions, providing setpoints, processing signals, performing calculations, and displaying data on a display device. Figure 1(Not depicted in the image) The controller 150 may be located at least partially inside or outside the housing 102 and may have an integral or composite structure as needed. Those skilled in the art will understand that the interior of the housing 102 need not be maintained under a perfect vacuum. For example, in a so-called “ambient (S)TEM,” a background atmosphere of a given gas is intentionally introduced / maintained within the housing 102. Those skilled in the art will also understand that, in practice, it may be advantageous to limit the volume of the housing 102 so that it extends substantially minimally away from the optical axis 108 where possible, in the form of a small tube (e.g., about 1 cm in diameter) through which the employed electron beam passes, but widen to accommodate structures such as the source 104, sample holder 114, screen 126, camera 130, detector 132, beam splitter device 134, etc.

[0040] In some examples, illuminator 110 may include beam-forming elements such as lenses and / or aperture plates / stops to suitably shape (focus) beam 106 into a relatively narrow "pencil" of charged particles, such that it illuminates only a relatively small area (coverage area) of sample 140 at any given time. Relative movement between sample 140 and the coverage area of ​​beam 106 to move the coverage area onto another area of ​​the sample can be generated in any of a variety of ways, such as by using positioning device 118 to move sample 106 relative to beam 140 and / or by using deflector 112 to deflect beam 106 relative to sample 140; moving source 104 and / or the aforementioned beam-forming elements to displace beam 106 relative to sample 140.

[0041] In some examples, for each such selected position of electron beam 106 relative to sample 140, a TEM camera 130 can be used to capture a diffraction pattern. Specifically, a controller 150 (or another processor device) may be programmed and / or configured to acquire a set of overlay imaging measurements by recording, for example, the output of the TEM camera 130 for each of a series of different positions of beam 106 on sample 140 (e.g., by sending a setpoint of an appropriate series to positioning device 118, deflector 112, etc.). Additionally or alternatively, the controller 150 may be programmed and / or configured to process the recorded outputs of the camera 130 and use them as inputs to perform a mathematical reconstruction algorithm. Additionally or alternatively, the controller 150 may be programmed and / or configured to display the results of the reconstruction algorithm, for example, in the form of an image on a display device (not shown).

[0042] Conjugate hidden-suppression configuration Figure 2 An example is illustrated of various aspects of an electron beam 202 passing through elements of a TEM 200 configured according to this disclosure. The TEM 200 can be described as representing... Figure 1An example of a CPM system 100, and compatible with... Figure 1 The CPM system can share any component, attribute, etc.

[0043] While this disclosure relates in general to examples where the CPM system under consideration is a TEM (e.g., TEM 200) and the charged particle beam is an electron beam (e.g., electron beam 202), this is not required for all examples. For instance, the methods and concepts disclosed herein are applicable to any suitable CPM system and / or other optical systems (such as STEM, SEM, and / or optical microscope systems) are also within the scope of this disclosure.

[0044] like Figure 2 As shown, TEM 200 includes a source module 210 with an electron source 212 (such as a field emission gun) that emits an electron beam 202 along an optical axis 204 toward a sample plane 252 where the sample is located. The electron beam 202 is focused by a gun lens 214 such that the electron beam 202 exhibits beam crossing at a crossing plane 206. The source module 210 may additionally or alternatively be referred to as a source optics assembly 210.

[0045] Source module 210 further includes source module aperture 218, which is configured to block part of electron beam 202 for any of a variety of purposes. For example, in some examples, source module 210 may include a monochromator ( Figure 2 (Not depicted in the text), the monochromator disperses the electron beam 202 to varying degrees based on electron energy, and the source module aperture can be configured to block all but a portion of the electron beam 202 corresponding to the desired energy range. Additionally or alternatively, the source module aperture 218 may include a beam deflector 216 and / or operate in conjunction with the beam deflector, as described in more detail below.

[0046] TEM 200 further includes a condenser module 230 downstream of source module 210, which shapes and / or otherwise configures the electron beam 202 before it reaches sample plane 252. Condenser module 230 includes a first condenser lens 232, a second condenser lens 234, a third condenser lens 238, and a fourth condenser lens 242, as well as a first condenser aperture 236 and a second condenser aperture 240. Condenser module 230 may additionally or alternatively be referred to as condenser optics assembly 230.

[0047] The first condenser lens 232, the second condenser lens 234, the third condenser lens 238, and / or the fourth condenser lens 242 can be used in conjunction with the first condenser aperture 236 and / or the second condenser aperture 240 to control various properties of the electron beam 202 guided to the sample (such as the diameter, collimation, and / or energy flux of the electron beam 202). For example, the relative intensity of the first condenser lens 232 and the second condenser lens 234 can determine the diameter and / or beam flux of the electron beam 202 in the plane of the first condenser aperture 236. The second condenser lens 234 and the third condenser lens 238 can be adjusted together to change the diameter and / or collimation of the electron beam 202 in the sample plane 252. The fourth condenser lens 242 can be used to change the magnification of the condenser module 230. The second condenser aperture 240 can be used to limit the illumination area in the sample plane 252.

[0048] TEM 200 also includes an objective lens module 250 downstream of the condenser module 230. For example... Figure 2 As shown, the objective lens module 250 includes a first objective lens 254 located upstream of the sample plane 252, a second objective lens 256 located downstream of the sample plane 252, and an intermediate lens 258 located downstream of the second objective lens 256. The objective lens module 250 may additionally or alternatively be referred to as the objective lens optics assembly 250.

[0049] The first objective lens 254 collimates the electron beam 202, while the second objective lens 256 focuses the electron beam 202 onto the back focal plane 260. The objective module 250 also includes an objective aperture 262 located at the back focal plane 260. The intermediate lens 258 images the back focal plane 260 onto a diffraction plane 270, at which the diffraction pattern 272 formed by the electron beam 202 can be recorded.

[0050] TEM 200 further includes a detector 280 positioned at detector plane 282 for recording diffraction patterns. Figure 2 In the example, detector plane 282 is coplanar with diffraction plane 270.

[0051] like Figure 2 As shown, when electron beam 202 encounters a sample in sample plane 252, the electron beam is modified by the sample to generate a modulated electron beam 202' downstream of sample plane 252. Specifically, modulated electron beam 202' may include a portion of electron beam 202 modified via interaction with the sample (such as via scattering interaction), such that modulated electron beam 202' contains information about the structure of the sample. Modulated electron beam 202' may also include a portion of electron beam 202 that passes through the sample substantially unchanged. Figure 2In the diagram, dashed lines illustrate the portions of electron beam 202 and / or modulated electron beam 202' that are modulated through interaction with the sample, while solid lines illustrate the portions of electron beam 202 and / or modulated electron beam 202' that are unaffected by the sample.

[0052] In any plane downstream of the sample plane 252, the modulated electron beam 202' can be described as having a modulated beam pattern. For example, in Figure 2 In the example, the rays of the modulated electron beam 202' are focused at the diffraction plane 270, such that the modulated beam pattern in the diffraction plane 270 includes and / or the diffraction pattern 272, which in Figure 2 In the example, the modulated beam pattern can take the form of spaced-out beam spots. In other planes, the modulated beam pattern can exhibit other shapes and / or forms, such as rings, disks, etc. In this way, the modulated beam pattern can be described as a cross-section representing the modulated electron beam 202' in the plane of interest.

[0053] In this disclosure, the term "diffraction plane" is intended to refer to a plane in which a portion of an electron beam 202 passing through the sample is focused by one or more optical elements downstream of the sample plane 252. Generally, the TEM 200 may include multiple such planes conjugate to each other. Reference Figure 2 For example, when the diffraction plane 270 is positioned downstream of the back focal plane 260, the electron beam 202 and the modulated electron beam 202' are also focused within the back focal plane 260. Therefore, the back focal plane 260 can also be described as another diffraction plane representing TEM 200. Generally, positioning the detector 280 at any such diffraction plane can be used to record the diffraction pattern generated by the sample. However, in practice, it may be advantageous to position the detector 280 at a diffraction plane (such as diffraction plane 270) where the diffraction pattern is magnified relative to the diffraction pattern in the back focal plane 260.

[0054] As described above, TEM 200 includes a beam deflector 216 that can be used to selectively redirect the electron beam 202 away from the sample. Figure 2 As shown, beam deflector 216 is positioned at deflector plane 208, which is located within source module 210. However, this is not required, and within the scope of this disclosure, deflector plane 208 may be located at different locations (such as locations away from source module 210 (e.g., downstream therefrom)), and deflector plane 208 does not need to be the same as or close to cross plane 206.

[0055] In some examples, beam deflector 216 can be used to guide the electron beam 202 away from the sample until an image (e.g., a diffraction pattern) is to be recorded, in order to protect the sample from damage by the electron beam 202. In this way, beam deflector 216 can be considered as a shutter mechanism that can be used to at least partially define the exposure time during which the electron beam 202 is guided to the sample.

[0056] Additionally or alternatively, beam deflector 216 can be configured to guide electron beam 202 to the sample in the form of short pulses, such that the sample is continuously and precisely excited by electron beam 202 for a controlled time interval. In this way, beam deflector 216 enables time-resolved analysis of the sample, where the duration of the electron beam pulses can be varied to study the effects of different degrees of sample excitation. As a more specific example, TEM 200 can be used to perform pump-probe microscopy studies, which utilize nonlinear optical imaging techniques for sample characterization and analysis. Additionally or alternatively, the use of beam deflector 216 allows the user to adjust the balance between temporal resolution (typically corresponding to shorter beam pulses) and signal strength (typically corresponding to longer beam pulses).

[0057] like Figure 2 As shown, beam deflector 216 can typically be configured to redirect electron beam 202 to generate a deflected beam 203 downstream of beam deflector 216, which can then be blocked by a blanking structure. Figure 2 In the example, the blanking structure is source module aperture 218. However, this is not required in all examples, and the beam deflector 216 may selectively guide the deflected beam 203 toward any other suitable structure, such as the first condenser aperture 236 or the second condenser aperture 240, which is also within the scope of this disclosure.

[0058] The beam deflector 216 can take any of a variety of forms. For example, the beam deflector 216 may include and / or may be an electrostatic beam deflector, wherein a voltage is selectively applied to opposing electrodes to selectively steer the electron beam 202 toward the blanking structure. As a more specific example, the electrostatic beam deflector may include rod-shaped electrodes located on either side of the optical axis 204, wherein one rod-shaped electrode is maintained at a ground potential and the other rod-shaped electrode is selectively reached at a deflection potential. When a significant potential difference is introduced between the electrodes, the resulting electric field can steer the trajectory of the electron beam 202 toward and / or toward the blanking structure.

[0059] Additionally or alternatively, the beam deflector 216 may include and / or may be a magnetic beam deflector, wherein a magnetic field (e.g., via an electric current) is selectively generated to deflect the electron beam 202.

[0060] Compared to magnetic beam deflectors, electrostatic beam deflectors enable faster switching between blanking and unblanked states. This can be particularly advantageous in the context of time-resolved studies with exposure durations on the order of nanoseconds. For example, in the case of magnetic beam deflectors, beam deflection can be achieved by generating a transverse magnetic field using magnetic materials. However, the slow settling time of magnetic domains in the magnetic material limits the speed at which the magnetic beam deflector can switch between blanking and unblanked states. Furthermore, such magnetic materials may be susceptible to hysteresis, which introduces a variable residual magnetic field for each blanking-unblanked cycle. In contrast, electrostatic beam deflectors can operate at high speeds between blanking and unblanked states relative to magnetic beam deflectors and are less susceptible to hysteresis.

[0061] Beam deflector 216 can be incorporated into TEM 200 in any suitable manner. For example, one or more components of beam deflector 216 may be coupled to and / or supported by a structure present in a conventional TEM system, such as a variable aperture mechanism. In other examples, TEM 200 may include a dedicated structure for maintaining beam deflector 216 in place relative to optical axis 204.

[0062] In this disclosure, when each point in one such plane is imaged onto a corresponding point in another such plane, two or more planes within and / or associated with the CPM system (such as TEM 200) can be described as conjugate to each other. For example, refer to Figure 2 Any one of the deflector plane 208, the back focal plane 260, and the diffraction plane 270 can be described as conjugate to each other.

[0063] As described in more detail below, configuring TEM 200 such that deflector plane 208 is conjugate with diffraction plane 270 and / or with detector plane 282 can benefit the performance of beam deflector 216. Specifically, in such a configuration, beam deflector 216 can cause the electron beam 202 to tilt in a pivot plane conjugate with detector plane 282. Thus, in such a configuration, beam deflector 216 is presented as stationary in detector plane 282 about the rest point of its deflecting electron beam 202, and beam deflector 216 transitions between a blanked state and an unblanked state. In this disclosure, such a configuration may generally be referred to as a conjugate blanking configuration.

[0064] Figures 3A to 3C This is a schematic representation of the path of the electron beam 302 passing through TEM 300, which can be connected to... Figure 2 TEM 200 and / or Figure 1 The CPM system 100% shares any suitable components, attributes, etc., as described in more detail below. Figures 3A to 3CAn example of an operation sequence according to this disclosure is illustrated, through which the TEM 300 can be put into a conjugate blanking configuration. As described in more detail below, Figure 3A This can be described as representing the initial configuration of TEM 300. Figure 3B It can be described as representing an intermediate configuration of TEM 300, and Figure 3C This can be described as representing the conjugate blanking configuration of TEM 300. However, it should be understood that... Figures 3A to 3C The illustrated configuration represents a non-exclusive example of an operational sequence according to this disclosure. For example, and as discussed in more detail below, another operational sequence according to this disclosure may be used with... Figure 3A The initial configurations described are different from the initial configurations.

[0065] like Figures 3A to 3C As shown, TEM 300 includes an electron source 310 that emits an electron beam 302 along an optical axis 301, a first optical element 312 (e.g., a lens), and a beam deflector 314 located at a deflector plane 332 downstream of the first optical element 312. TEM 300 further includes a second optical element 316 (e.g., a lens) downstream of the deflector plane 332 and a third optical element 318 (e.g., a lens) downstream of the second optical element 316. The electron beam 302 is incident on a sample positioned at a sample plane 338, and a detector 322 is positioned at a detector plane 324 to record a modulated beam pattern (e.g., a diffraction pattern) formed by the electron beam 302 downstream of the sample plane 338. A fourth optical element 320 (e.g., a lens) is positioned between the sample plane 338 and the detector plane 324, such as to focus the electron beam 302 to form a diffraction pattern in a diffraction plane 340.

[0066] For simplicity, Figures 3A to 3C The trajectory of the electron beam 302, shaped and / or guided by the optical elements of the TEM 300, is illustrated, but diffraction effects that may be introduced when the sample is positioned at the sample plane 338 are not depicted. However, it should be understood that references to this text are not intended to obscure the diffraction effects. Figures 3A to 3C The described characteristics and properties may also relate to examples in which the electron beam 302 is diffracted by a sample positioned at the sample plane 338. Therefore, refer to... Figures 3A to 3C The description of the methods and / or procedures presented may refer to examples in which the sample is positioned at the sample plane 338 and examples in which the sample is removed from the sample plane 338.

[0067] Similarly, while the diffraction plane 340 corresponds to the plane in which the electron beam 302 forms a diffraction pattern when diffracted by a sample, this plane may be referred to as the diffraction plane 340 even in examples where the electron beam 302 is not diffracted by a sample. For example, and as discussed in more detail below, the diffraction plane 340 may refer to the plane in which the diffracted or non-diffracted electron beam exhibits beam crossing and / or focusing. In other words, the diffraction plane 340 refers to the plane in which a diffraction pattern is formed or will be formed when the electron beam 302 is diffracted by a sample, regardless of the presence of a sample. Therefore, reference to the diffraction plane 340 herein is not intended to imply that the corresponding electron beam is diffracted by a sample upstream of the diffraction plane 340.

[0068] The first optical element 312, the second optical element 316, the third optical element 318, and / or the fourth optical element 320 may each include and / or may be any suitable optical element, such as those referenced above. Figures 1 to 2 The optical elements described. For example, the first optical element 312 may represent, include, and / or be one or more lenses of the source module, such as... Figure 2 Gun lens 214.

[0069] Additionally or alternatively, the second optical element 316 may represent, include, and / or be one or more lenses of a condenser module, such as Figure 2 The first condenser lens 232, the second condenser lens 234, the third condenser lens 238 and / or the fourth condenser lens 242.

[0070] Additionally or alternatively, the third optical element 318 and the fourth optical element 320 may each represent, include, and / or be one or more lenses of an objective lens module, such as Figure 2 The first objective lens 254, the second objective lens 256, and / or the intermediate lens 258. As a more specific example, the third optical element 318 may include and / or may be an objective lens element, such as... Figure 2 The first objective lens 254, and the fourth optical element 320 may include and / or may be another objective lens element, such as Figure 2 The second objective lens 256. In some examples, the diffraction plane 340 may be the back focal plane associated with the fourth optical element 320 or may be a plane conjugate to such a back focal plane.

[0071] Figures 3A to 3C Additionally, the path of a partially deflected beam 304 is illustrated by dashed lines. This partially deflected beam represents the portion of the electron beam 302 that is partially redirected away from the optical axis 301 and / or the sample by the beam deflector 314. Specifically, although the beam is fully deflected by the beam deflector 314 in a blanking state (e.g., Figure 2The deflected beam 203 does not reach the sample plane 338 or the diffraction plane 340, but the beam deflector 314 cannot instantaneously generate such a fully deflected beam. Instead, as the beam deflector 314 transitions towards the blanking state, it generates a series of continuous partially deflected beams that travel along the same path as the sample plane 338 or the diffraction plane 340. Figures 3A to 3C The trajectory shown in the dashed line in the middle reaches the sample plane 338 and / or the diffraction plane 340.

[0072] Figures 3A to 3C The partial deflection beam 304 of any of these can be understood as representing any such beam trajectory associated with an intermediate state of the beam deflector 314, defined between an unblanked state and a fully blanked state. As used herein, the intermediate state of the beam deflector 314 may additionally or alternatively be referred to as a partially blanked state and / or a partially deflected state. In this way, the beam deflector 314 can be described as transitioning between multiple (e.g., consecutive multiple) intermediate states and / or partially deflected states as the beam deflector 314 transitions between an unblanked state and a fully blanked state. Generally, each partially blanked state can produce a corresponding trajectory of the electron beam 304 downstream of the beam deflector 314 and / or a corresponding beam pattern at the detector plane 324. Figures 3A to 3C The electron beam 302 shown in solid line in the middle can also be referred to as the unblanked electron beam 302 and / or the undeflected electron beam 302.

[0073] In this way, terms used herein to characterize the state and / or configuration of electron beam 302 and / or beam deflector 314 (such as “partial deflection” and / or “partial blanking”) do not necessarily refer to states and / or configurations in which the elements of TEM 300 are intentionally put into and / or maintained. Rather, such terms are generally understood to refer to any of a variety of intermediate states and / or configurations that are typically only temporarily realized during the operation of the TEM, but can still be illustrative in describing the operation of beam deflector 314 between blanked and unblanked states.

[0074] Figure 3A The configuration of TEM 300 is illustrated, in which the operating beam deflector 314 can cause the electron beam 302 to move laterally in the diffraction plane 340. Figure 3A This can be described as an example representing the initial configuration of TEM 300; for example, before TEM is put into a conjugate blanking configuration. Specifically, in Figure 3AIn the example, the diffraction plane 340 is coplanar with the detector plane 324, such that the diffraction pattern formed by the electron beam 302 is focused onto the detector 322. However, as can be seen by comparing the trajectories of the undeflected electron beam 302 and the partially deflected beam 304 at the detector plane 324, operating the beam deflector 314 between the blanking and unblanking states causes the focused spot of the electron beam to move within the detector plane 324. Therefore, when the beam deflector 314 transitions from the unblanking state to the blanking state, visible fringes may appear in the diffraction pattern recorded by the detector 322 before the electron beam 302 is completely blanked.

[0075] Figure 4 An example of fringe 410 is illustrated, which may be formed in a diffraction plane (e.g., diffraction plane 340) and / or recorded by a detector (e.g., detector 322) when a beam deflector (e.g., beam deflector 314) transitions from an un-blinded state to a fully-blinded state. Specifically, Figure 4 An example is illustrated by unseen spot 402 and partially seen spot 404 connected by stripes 410 having a stripe length of 412. Unseen spot 402 and partially seen spot 404 can be described as corresponding to, respectively, a stripe 410 connected by stripes 410 of length 412. Figure 3A The spots formed by the undeflected electron beam 302 and the partially deflected beam 304 are recorded by the detector 322. The stripe 410 connecting the undeflected beam spot 402 and the partially deflected beam spot 404 can be described as representing the path traced by the focused electron beam in the detector plane as the beam deflector transitions toward a fully blanked state.

[0076] Although Figure 4 Examples of fringes that can be associated with focused beam spots in a diffraction pattern are illustrated, but it should be understood that such descriptions similarly apply to features of diffraction patterns and / or focused and / or unfocused electron beams, such as rings, disks, etc. In such cases, the fringes may additionally or alternatively appear as blurring and / or elongation of such features.

[0077] As discussed above, the presence of such fringes 410 in the recorded diffraction pattern can be particularly undesirable in applications such as nanosecond-level time-resolved pump-probe studies, where the time interval required for the beam deflector to transition between un-blinded and fully-blinded states is a significant proportion of the total exposure time. In contrast, the conjugate blanking configuration of the TEM described herein produces a diffraction beam spot that is substantially stationary in the detector plane as the beam deflector transitions between un-blinded and fully-blinded states. Therefore, the form and / or details of the diffraction pattern remain substantially unmodified by the blanking or un-blinding electron beam process.

[0078] As used herein, the term "substantially stationary" for describing and / or characterizing a beam spot or pattern in a given plane (e.g., in a diffraction plane and / or a detector plane) can refer to a beam spot or pattern that remains fixed in position relative to the plane and / or a beam spot or pattern that moves only slightly relative to the plane. For example, a beam spot or pattern can be described as being "substantially stationary" during processes in which the orientation and / or shape of the beam spot or pattern shifts, such as by changes in size and / or rotational orientation about a point held within the beam spot or pattern. Additionally or alternatively, a beam spot or pattern can be described as being "substantially stationary" during processes in which the center point (e.g., centroid) of the beam spot or pattern is offset by a certain proportion (less than 50%, 40%, 30%, 20%, and / or 10% of the maximum linear dimension of the beam spot or pattern).

[0079] Return to Figure 3A The lateral shift of the focused spots of the undeflected electron beam 302 and the partially deflected beam 304 can be described as being caused by the axial separation of the deflector plane 332 from the intersecting plane 330 in which the electron beam 302 (e.g., via the first optical element 312) is focused. The intersecting plane 330 can be described as representing a first intersecting plane 330, in which the undeflected electron beam 302 and the partially deflected beam 304 are further focused into a second intersecting plane 334.

[0080] In this disclosure, the term "intersecting plane" can refer to any plane in which various rays characterizing a given beam (e.g., electron beam 304) are focused to a single point and thus "intersect" with each other. Therefore, reference... Figure 3A The diffraction plane 340 can also be described as a third intersecting plane 340. A given beam (e.g., an electron beam) does not need to be precisely focused to a point in the intersecting plane, and the intersecting plane may additionally or alternatively refer to the plane in which the beam diameter reaches a non-zero local minimum (e.g., due to optical aberrations) also within the scope of this disclosure.

[0081] exist Figure 3A In the example, the third intersection plane 340 is coplanar with the detector plane 324. Therefore, Figure 3A This can be described as an example depicting an initial configuration in which the electron beam 302 is focused onto the detector 322. However, this is not necessary for all examples. For example, additionally within the scope of this disclosure, the TEM 300 may be derived from... Figure 3A Initial configurations other than those shown (such as initial configurations where the third cross plane 340 is located upstream or downstream of detector plane 324) enter Figure 3C The conjugate hidden-suppression configuration.

[0082] Figures 3A to 3C The configuration shown can also be described with reference to a series of planes conjugate to deflector plane 332. For example, as Figure 3A As shown, the illustrated configuration exhibits a first conjugate deflector plane 336 and a second conjugate deflector plane 342, each conjugate with the deflector plane 332.

[0083] Figure 3C An example is TEM 300 in a conjugate blanking configuration, while Figure 3B An example is shown when TEM 300 is entered. Figure 3C The example of the conjugate hidden-suppression configuration method is an intermediate configuration of TEM 300 that can be achieved during the process. Specifically, relative to Figure 3A Configuration, Figure 3B An example is illustrated in which the fourth optical element 320 has been adjusted to move the second conjugate deflector plane 342 to an axial alignment with the detector plane 324. For example, the fourth optical element 320 may include and / or may be an objective lens element (e.g., Figure 2 The second objective lens 256), and the TEM 300 from Figure 3A The configuration has been changed to Figure 3B The configuration can correspond to adjusting the objective lens elements to shorten their focal length.

[0084] like Figure 3B As shown, moving the second conjugate deflector plane 342 to axially align with the detector plane 324 can have the effect of displacing the diffraction plane 340 away from the detector plane 324, such as displacing it to an axial position upstream of the detector plane 324. Therefore, in this example, it allows the TEM 300 to enter... Figure 3B The intermediate configuration can be described as having the effect of moving the focal plane of the electron beam 302 away from the detector plane 324, thereby defocusing the electron beam 302 in the detector plane 324. However, this is not necessary in all examples, and bringing the TEM 300 into the intermediate configuration may include bringing the diffraction plane 340 closer to the detector plane 324, which is also within the scope of this disclosure.

[0085] As used herein, the term “axial alignment” for describing and / or characterizing two or more entities (e.g., parts, points, planes, etc.) refers to a configuration in which the entities are located in a common axial position (e.g., relative to and / or along the optical axis 301).

[0086] like Figure 3BAs shown, the intermediate configuration of TEM 300 corresponds to a configuration in which the undeflected electron beam 302 and the partially deflected beam 304 form overlapping spots in the detector plane 324. In this configuration, the detector plane 324 is conjugate with the deflector plane 332. Because the detector plane 324 is axially separated from the diffraction plane 340, the spots corresponding to the undeflected electron beam 302 and the partially deflected beam 304 can be described as unfocused spots. Because the spots corresponding to the undeflected electron beam 302 and the partially deflected beam 304 overlap in the detector plane 324, the position of this beam spot remains substantially stationary when the beam deflector 314 transitions between an unblinded state and a fully blinded state.

[0087] Transform TEM 300 from Figure 3B The intermediate configuration was transformed to Figure 3C The conjugate blanking configuration corresponds to focusing the undeflected electron beam 302 and the partially deflected beam 304 onto the detector plane 324, while maintaining these focused spots in an overlapping configuration. Specifically, the transformation of the TEM 300 can be performed by adjusting the first optical element 312 to axially align the first cross plane 330 with the deflector plane 332. Figure 3C The configuration. As a more specific example, the first optical element 312 may include and / or may be Figure 2 The gun lens 214, and can perform the conversion of TEM 300 into a focal length by increasing the focal length of the first optical element 312. Figure 3C The configuration of the electron beam 302 is such that, because the setup of the gun lens (e.g., excitation and / or focal length) at least partially determines the axial position of the first cross plane 330, the TEM 300 can be constrained to be used in such a gun lens setup during subsequent sample analysis. However, it should be understood that various other aspects of the electron beam 302 can be adjusted when the TEM 300 is in a conjugate blanking configuration. For example, with the TEM 300 in a conjugate blanking configuration, the width of the electron beam at the sample plane 338 can be adjusted, such as to change the area of ​​the sample illuminated at the sample plane 338. Such adjustments can be performed, for example, by adjusting optical elements downstream of the deflector plane 332 and upstream of the sample plane 338 (such as a second optical element 316 and / or a third optical element 318). As another example, with the TEM 300 in a conjugate blanking configuration, the magnification of the diffraction pattern formed by the electron beam 302 at the detector plane 324 can be adjusted, for example, by adjusting optical elements downstream of the sample plane 338 (e.g., a fourth optical element 320).

[0088] exist Figure 3CIn this configuration, the deflector plane 332 is conjugate with each of the diffraction plane 340 and the detector plane 324, as well as with the second cross plane 334. Therefore, as the beam deflector 314 transitions from an unblanked state to a fully blanked state, the electron beam 302 remains focused on one or more positions (e.g., the diffraction pattern) that remain substantially stationary in the detector plane 324. When the beam deflector 314 reaches the fully blanked state, the electron beam 302 stops reaching the detector plane 324, and the diffraction pattern substantially darkens and / or disappears without exhibiting blurring and / or fringing.

[0089] Figures 3A to 3C An operational sequence is illustrated, through which the electron beam 302 of the TEM 300 is focused onto the detector plane 324. Figure 3A The initial state of ) enters the conjugate hidden-elimination configuration ( Figure 3C In other examples, a similar sequence of operations can be used to bring TEM 300 into focus when electron beam 302 is not initially focused at detector plane 324. Figure 3C The conjugate hidden-suppression configuration.

[0090] For example, the electron beam 302 may initially be underfocused, such that the third cross plane 340 is initially positioned downstream of the detector plane 324. In such an example, converting the TEM 300 to a conjugate blanking configuration may include first converting the TEM 300 by axially aligning the second conjugate deflector plane 342 with the detector plane 324. Figure 3B The intermediate configuration. Similar to... Figures 3A to 3B For example, this can be achieved by shortening the focal length of the fourth optical element 320 to move the second conjugate deflector plane 342 in the upstream direction. In some examples, this can have the effect of moving the third intersecting plane 340 upstream through and past the axial position of the detector plane 324, such that as the TEM 300 changes to an intermediate configuration, the electron beam 302 sequentially increases and decreases in focus at the detector plane 324.

[0091] As another example, the electron beam 302 may initially be overfocused, such that the third cross plane 340 is initially positioned upstream of the detector plane 324. In such examples, reverting the TEM 300 to a conjugate blanking configuration may involve first aligning the second conjugate deflector plane 342 axially with the detector plane 324 to convert the TEM 300 to a conjugate blanking configuration. Figure 3B The intermediate configuration. In this example, this can be achieved by increasing the focal length of the fourth optical element 320 to move the second conjugate deflector plane 342 in the downstream direction.

[0092] However, the configuration in which the electron beam 302 is initially overfocused can correspond to a configuration in which the second conjugate deflector plane 342 is initially located upstream or downstream of the detector plane 324. Therefore, axially aligning the second conjugate deflector plane 342 with the detector plane 324 can result in increasing and / or decreasing the degree of focus of the electron beam 302 at the detector plane 324 when the TEM 300 is switched to an intermediate configuration.

[0093] Generally, when the TEM 300 is initially configured such that the electron beam 302 is not focused at the detector plane 324, it may be unknown whether the electron beam 302 is underfocused or overfocused relative to the detector plane 324. Therefore, it may be unknown whether the second conjugate deflector plane 342 needs to be moved in the upstream or downstream direction to axially align the second conjugate deflector plane 342 with the detector plane 324.

[0094] Therefore, transforming TEM 300 from any initial configuration to an intermediate configuration may include iteratively shifting the second conjugate deflector plane 342 above the upstream or downstream direction and measuring the effect of such shift. For example, since the intermediate configuration corresponds to a configuration in which the undeflected electron beam 302 and the partially deflected beam 304 overlap in the detector plane 324, the intermediate configuration can be achieved by iteratively shortening and / or minimizing the stripe length between the undeflected electron beam 302 and the partially deflected beam 304 during operation of the beam deflector 314.

[0095] Figures 3A to 3C An operational sequence is described in which the TEM 300 is brought into a conjugate blanking configuration by first axially aligning the second conjugate deflector plane 342 with the detector plane 324 and then axially aligning the first cross plane 330 with the deflector plane 332. Performing such adjustments in this sequence ensures that the detector plane 324 remains conjugate with the deflector plane 332, while the electron beam 302 is focused onto the detector plane 324 via the first optical assembly 312.

[0096] However, this sequence is not required in all examples. For example, the TEM 300 can also be brought into a conjugate blanking configuration by iteratively adjusting an upstream optics element (e.g., first optics element 312) located upstream of the deflector plane 332 to a selected setting, focusing the electron beam 302 onto the detector plane 324 by a downstream optics element (e.g., fourth optics element 320) located downstream of the deflector plane 332, and measuring the fringe length between the undeflected electron beam 302 and the partially deflected beam 304. In some examples, bringing the upstream optics to a selected setting may include adjusting the focal length of the upstream optics to adjust the defocus of the electron beam 302 at the deflector plane 324. Therefore, repeating these steps with different selected settings (e.g., focal lengths) of the upstream optics allows for comparisons between fringe lengths corresponding to such settings. The differences (e.g., sign and magnitude) between the successively measured fringe lengths can then be used to iteratively select subsequent settings for the upstream optics until the measured fringe lengths are minimized when the electron beam 302 is focused at the detector plane 324, at which point the TEM 300 can be understood as being in a conjugate blanking configuration. Such an iterative process can be performed manually and / or at least partially automatically.

[0097] Figures 5A to 5B This indicates that before putting the TEM into the conjugate blanking configuration ( Figure 5A ) and afterwards ( Figure 5B An example of the diffraction pattern of a gold sample recorded. That is, Figure 5A This can be described as indicating that TEM is in relation to Figure 3A An example of a diffraction pattern 500 recorded in diffraction plane 502, with a similar initial configuration. Figure 5B This can be described as representing the state of the same TEM as... Figure 3C An example of the corresponding diffraction pattern 500' recorded under the conjugate blanking configuration shown.

[0098] exist Figures 5A to 5B In each of these, a diffraction pattern is recorded by a detector (e.g., detector 322) during exposure terminated by switching the beam deflector (e.g., beam deflector 314) to a fully blanked state. Figures 5A to 5B As shown, compared to the corresponding diffraction pattern 500' obtained when the TEM is in a conjugate blanking configuration, the diffraction pattern 500 obtained when the TEM is not in a conjugate blanking configuration exhibits significantly more blurry and poorly resolved features. Specifically, the comparison... Figures 5A to 5B It can be seen that the diffraction pattern 500 is blurred along the blur direction 504, which makes the radius of each feature of the diffraction pattern 500 more difficult to measure accurately than in the example of diffraction pattern 500'.

[0099] Figures 6A to 6BThis indicates that before putting the TEM into the conjugate blanking configuration ( Figure 6A ) and afterwards ( Figure 6B Additional examples of diffraction patterns of single-crystal gallium nitride recorded. That is, Figure 6A This can be described as indicating that TEM is in relation to Figure 3A An example of a diffraction pattern 600 recorded in diffraction plane 602, with a similar initial configuration. Figure 6B This can be described as representing the state of the same TEM as... Figure 3C An example of the corresponding diffraction pattern 600' recorded under the conjugate blanking configuration shown. Figures 5A to 5B An example of a diffraction pattern comprising a series of diffraction rings is shown, while Figures 6A to 6B Examples of diffraction patterns including spaced and localized diffraction spots are shown.

[0100] exist Figures 6A to 6B In each of these, a diffraction pattern is recorded by a detector (e.g., detector 322) during exposure terminated by switching the beam deflector (e.g., beam deflector 314) to a fully blanked state. Figures 6A to 6B As shown, compared to the corresponding diffraction pattern 600' obtained when the TEM is in a conjugate blanking configuration, the diffraction pattern 600 obtained when the TEM is not in a conjugate blanking configuration exhibits significantly more blurry and poorly resolved features. Specifically, the comparison... Figures 6A to 6B It can be seen that the diffraction pattern 600 is blurred along the blur direction 604, which makes the position of each feature of the diffraction pattern 600 more difficult to measure accurately than in the example of diffraction pattern 600'.

[0101] Exemplary methods Figure 7 This is a flowchart illustrating an example of a method 700 for operating a CPM system, which includes a beam deflector positioned at a deflector plane and configured to guide a beam of charged particles toward a sample to generate a diffraction beam pattern at a diffraction plane. Method 700 can be performed in conjunction with any suitable CPM system. For example, the CPM system may include and / or may be Figure 1 CPM system 100 Figure 2 TEM 200 and / or Figures 3A to 3C The TEM 300 and / or any suitable portions thereof. The CPM system may additionally or alternatively include any suitable features and / or characteristics not specifically described herein.

[0102] Any system component discussed and / or described in reference method 700 herein may be understood to represent and / or refer to similarly named components and / or functional equivalents of CPM system 100, TEM 200, and / or TEM 300. For example, the beam deflector described in reference method 700 herein may represent Figure 1 Deflector 112, Figure 2 Beam deflector 216 and / or Figures 3A to 3C The beam deflector 314. In this way, method 700 can be understood in the context of the above description of CPM system 100, TEM 200 and / or TEM 300, and vice versa. However, this is not necessary, and method 700 can be performed with any suitable components, which is also within the scope of this disclosure.

[0103] like Figure 7 As shown, method 700 includes adjusting one or more optical elements of the CPM system at 710 such that the deflector plane is conjugate with the diffraction plane. Method 700 further includes recording the diffraction beam pattern at 730 using a detector positioned at the diffraction plane.

[0104] As described herein, adjusting the optical elements at 710 may include adjusting the position (e.g., axial position) of the diffraction plane at 712 to align the diffraction plane with the detector axis. For example, a CPM system may include a first optical assembly located upstream of the deflector plane and a second optical assembly located downstream of the deflector plane, and adjusting the position of the diffraction plane at 712 may include adjusting one or more optical elements of the second optical assembly at 714. Specifically, adjusting the position of the diffraction plane at 712 may include adjusting the optical elements of the second optical assembly at 714 to position the diffraction plane in the axial direction (e.g., along the detector axis). Figures 3A to 3C The optical axis (301) is shifted. (Reference) Figure 2 For example, in TEM 200, the first optical assembly may include one or more components of the source module 210 upstream of the beam deflector 216, and / or the second optical assembly may include one or more components of the condenser module 230 and / or the objective lens module 250. Therefore, as a more specific example, adjusting the optical elements of the second optical assembly at 714 may include adjusting the second objective lens 256 and / or the intermediate lens 258 to shift the axial position of the diffraction plane, as discussed above.

[0105] As an additional (or alternative) example, and for reference Figures 3A to 3CIn the CPM system 300, the first optical assembly may include and / or may be a first optical element 312, and the second optical assembly may include and / or may be any of a second optical element 316, a third optical element 318, and / or a fourth optical element 320. Therefore, as a more specific example, adjusting the optical element of the second optical assembly at 714 may include adjusting the fourth optical element 320 to shift the axial position of the diffraction plane, as discussed above.

[0106] As discussed above, a diffraction plane can refer to the plane in which a diffraction pattern is formed when a beam of charged particles passes through a sample, and the plane can still be called a diffraction plane even when the sample and / or diffraction pattern is not present.

[0107] In some examples, and such as Figure 7 As shown, adjusting the optical element of the second optical assembly at 714 may include adjusting the focal length of an element of the second optical assembly at 716. For example, the second optical assembly may include an objective lens, such as... Figure 2 The second objective lens 256 and / or intermediate lens 258, and adjusting the position of the diffraction plane at 712 may include adjusting the focal length of the objective lens to align the diffraction plane with the detector axis.

[0108] like Figure 7 As shown, adjusting the optical element at 710 may further include adjusting one or more optical elements of the first optical assembly at 720 to align the crossing plane of the charged particle beam with the detector axis. Specifically, in some examples, and as... Figure 9 As shown, adjusting the optical element of the first optical component at 720 includes adjusting the focal length associated with the first optical component at 722.

[0109] As a more specific example, and refer to Figure 2 The TEM 200, at 720, may include adjusting the optical elements of the first optical assembly, such as to change the focal length of the gun lens 214. Additionally or alternatively, and referring to... Figures 3A to 3C The CPM system 300, at 720, may adjust the optical elements of the first optical component, such as by adjusting its focal length.

[0110] In some examples, the focal length of the first optical component adjusted during the adjustment at 722 may be referred to as the first focal length, and the focal length of the second optical component adjusted during the adjustment at 716 may be referred to as the second focal length.

[0111] Adjusting the first focal length at 722 and / or adjusting the second focal length at 716 can each be performed in any suitable manner. For example, the optical element adjusted during adjusting the optical element of the first optical assembly at 720 and / or adjusting the optical element of the second optical assembly at 714 may include and / or may be an electro-optic lens element, and adjusting the focal length at 716 and / or at 722 may include adjusting the excitation voltage applied to such a lens element. In some examples, this may be at least partially controlled by a controller (such as...) Figure 1 The controller 150 is used to execute this.

[0112] Adjusting the optical elements of the first optical assembly at 720 and / or adjusting the first focal length at 722 may include adjusting such that the crossing plane of the charged particle beam (e.g., Figures 3A to 3C The first intersecting plane 330) is axially aligned with the deflector plane. Additionally or alternatively, adjusting the optical elements of the second optical assembly at 714 and / or adjusting the second focal length at 716 may include adjustments such that the conjugate deflector plane (e.g., Figures 3A to 3C The second conjugate deflector plane 342 is axially aligned with the detector plane, as described herein.

[0113] In some examples, after adjusting the optical elements of the second optical assembly at 714, adjusting the optical elements of the first optical assembly at 720 is performed. In some such examples, when the CPM system is in an initial configuration in which the charged particle beam is focused at the detector plane, adjusting the optical elements of the second optical assembly at 714 may include adjustments such that the charged particle beam becomes unfocused (and / or increasingly unfocused) at the detector. However, this is not necessary in all examples. For example, adjusting the optical elements of the second optical assembly at 714 may also be performed when the CPM system is in an initial configuration in which the charged particle beam is underfocused or overfocused relative to the detector plane.

[0114] Generally, and as discussed above, it may not be known initially whether the charged particle beam is underfocused or overfocused in the initial configuration of the CPM system. Therefore, adjusting the optical elements of the second optical assembly at 714 may include iteratively adjusting the optical elements, measuring the effect of each adjustment, and performing subsequent adjustments based on the measured effects.

[0115] For example, in any given configuration of the second optical component, method 700 may include operating a beam deflector between an unblinded state and a blanked state (e.g., a partially blanked state or a fully blanked state), and recording the initial fringe length formed by the charged particle beam in the detector plane when operating the beam deflector between the unblinded state and the blanked state. Recording the fringe length may be performed in any suitable manner, such as as referenced herein. Figure 4 The way it is described.

[0116] Then, adjusting the optical elements of the second optical assembly at 714 may include adjusting the focal length of the second optical assembly in the first direction, such as moving the conjugate deflector plane in the upstream direction, and recording an updated fringe length when operating the beam deflector between the un-blanked and blanked states. If the updated fringe length is less than the initial fringe length, adjusting the optical elements of the second optical assembly at 714 to further move the conjugate deflector plane in the first direction and measuring a new updated fringe length may be performed. If the updated fringe length is greater than the initial fringe length, adjusting the optical elements of the second optical assembly at 714 to move the conjugate deflector plane in a second direction opposite to the first direction and measuring a new updated fringe length may be performed. Such operations may be performed iteratively until the measured fringe length is minimized, which may indicate that the conjugate deflector plane is axially aligned with the detector plane.

[0117] In a configuration in which the conjugate deflector plane is axially aligned with the detector plane, the charged particle beam can form a beam pattern that is defocused at the deflector plane. Method 700 may then include performing an optical element adjustment at 720 of the first optical assembly such that the beam pattern is refocused at the detector and / or enhanced in terms of focus.

[0118] The beam pattern at the detector can refer to any suitable form and / or pattern of the charged particle beam in the detector plane, regardless of whether the charged particle beam is modulated by the sample at the sample plane. For example, the beam pattern at the detector can include and / or be a modulated beam pattern, which in turn can refer to any suitable portion and / or feature of the charged particle beam downstream of the sample that is deflected (e.g., diffracted) and / or otherwise altered by interaction with the sample, such as Figure 2 The modulated electron beam 202'. Additionally or alternatively, the beam pattern at the detector may include and / or may be any suitable portion and / or feature of the charged particle beam that is substantially unmodified by interaction with the sample.

[0119] In this disclosure, the degree of focus of a beam pattern and / or its features in a given plane can be characterized by the feature (e.g., maximum) diameter of the beam pattern in the given plane. Specifically, when such feature diameter decreases, the degree of focus can be described as an increase and / or improvement.

[0120] Recording the diffraction beam pattern at 730 can be performed in any suitable manner. For example, the diffraction beam pattern recorded by the detector can include and / or can be any suitable pattern, such as a diffraction pattern (e.g., a diffraction map) including diffraction spots, rings, disks, etc. The detector can include and / or can be any suitable detector, such as Figure 1 TEM camera 130 Figure 2 Detector 280 and / or Figures 3A to 3C The detector 322. Recording the diffraction beam pattern at 730 can be performed by a sample positioned in the sample plane, such that the sample modulates the charged particle beam to produce the diffraction beam pattern. However, as discussed above, other aspects of method 700 can be performed when the sample is positioned in the sample plane or when the sample is removed from the sample plane.

[0121] Figure 8 This is a flowchart illustrating an additional example of a method 800 for operating a CPM system according to this disclosure. Method 800 can be performed in conjunction with any suitable CPM system. For example, the CPM system may include and / or may be... Figure 1 CPM system 100 Figure 2 TEM 200 and / or Figures 3A to 3C The TEM 300 and / or any suitable portions thereof. The CPM system may additionally or alternatively include any suitable features and / or characteristics not specifically described herein.

[0122] Any system component discussed and / or described in reference method 800 herein may be understood to represent and / or refer to similarly named components and / or functional equivalents of CPM system 100, TEM 200, and / or TEM 300. For example, the beam deflector described in reference method 800 herein may represent Figure 1 Deflector 112, Figure 2 Beam deflector 216 and / or Figures 3A to 3C The beam deflector 314. In this way, method 800 can be understood in the context of the above description of CPM system 100, TEM 200 and / or TEM 300, and vice versa. However, this is not necessary, and method 800 can be performed with any suitable components, which is also within the scope of this disclosure.

[0123] In addition, this article references Figure 8 Any method disclosed may also be described as including and / or representing references herein. Figure 7 Any disclosed method steps, and vice versa. For example, methods 700 and 800 may include steps performed in a substantially similar manner and / or producing similar effects.

[0124] like Figure 8As shown, method 800 includes guiding a charged particle beam 810 to a sample, which modulates the charged particle beam to create a beam pattern downstream of the sample. Method 800 further includes switching a beam blanker of a CPM system between an unblanked state and a blanked state at 840, and recording the beam pattern by a detector at 850. When the beam blanker is in the unblanked state, the charged particle beam can reach the sample and create a beam pattern downstream of the sample. When the beam blanker is in the blanked state, the beam blanker guides the charged particle beam away from the sample, as described above. Figure 2 The methods discussed.

[0125] A beam blanking device can also be called a beam deflector. Examples of beam blanking devices that can be used in conjunction with method 800 include... Figure 1 Deflector 112, Figure 2 Beam deflector 216 and / or Figures 3A to 3C The beam deflector 314. During the recording of the beam pattern at least at 850, the beam blanker is positioned at the deflector plane, and the detector is positioned at the detector plane conjugate to the deflector plane.

[0126] During the recording of the beam pattern at least 850 locations, the beam pattern may include one or more beam pattern features focused in the detector plane. Such beam pattern features may include and / or may be spots, rings, disks, etc. (Reference) Figure 2 For example, the beam pattern feature may include and / or may be a diffraction pattern 272 formed by the electron beam 202 and the modulated electron beam 202' in the detector plane 282.

[0127] The executable method 800 is such that when the beam blanker transitions between an unblanked state and a blanked state, the beam pattern features are substantially stationary in the detector plane. In this way, and as discussed above, the transition of the beam blanker between the unblanked and blanked states allows the beam pattern to be exposed to the detector without introducing the aforementioned... Figure 4 Stripes and / or discussed in the context Figure 5A The features shown are blurred. As discussed above, this can be particularly advantageous in examples where a beam blanker is used to perform ultrafast time-resolved studies of samples (such as by exposing the sample to an electron beam for durations on the order of nanoseconds). As a more specific example, method 800 can be performed by an electrostatic beam blanker and / or the beam blanker at 840 can be switched over a time period of less than 10 nanoseconds (ns).

[0128] like Figure 8As shown, method 800 may include configuring the CPM system at 820 in a conjugate blanking configuration, which results in the beam pattern features remaining substantially static, as discussed above. When the CPM system is in the conjugate blanking configuration, the deflector plane is conjugate to the detector plane, and the intersection of the charged particle beams (e.g., its focal plane) is located at the deflector plane (e.g., aligned with its axis).

[0129] In some examples, configuring the CPM system at 820 may be performed at least partially after the charged particle beam is directed to the sample at 810. In some such examples, aspects of configuring the CPM system at 820 may include observing, measuring, and / or recording the portion of the charged particle beam in the deflector plane that is modulated (e.g., diffracted) by the sample. Additionally or alternatively, configuring the CPM system at 820 may be performed at least partially before the charged particle beam is directed to the sample at 810. In some such examples, aspects of configuring the CPM system at 820 may include observing, measuring, and / or recording the portion of the charged particle beam in the deflector plane that is not modified by the sample and / or does not interact with the sample. As a more specific example, such aspects of configuring the CPM system at 820 may be performed when the sample is removed from the beam path of the charged particle beam.

[0130] Configuring the CPM system at point 820 can be done in any of several ways. For example, and as... Figure 8 As shown, configuring the CPM system at 820 may include entering an intermediate configuration of the CPM system at 822, wherein the detector plane is conjugate to the deflector plane. Configuring the CPM system at 820 may also include entering the intermediate configuration of the CPM system at 822, and then entering a conjugate blanking configuration of the CPM system at 832. (See reference) Figures 3A to 3C , Figure 3B This can be described as an example demonstrating an intermediate configuration, while Figure 3C This can be described as an example of a conjugate hidden-cancellation configuration.

[0131] In some examples, and such as Figure 8 As shown, putting the CPM system into an intermediate configuration at 822 includes setting the conjugate deflector plane (e.g., at 824) to the intermediate configuration. Figures 3A to 3C The second conjugate deflector plane 342) is shifted to be axially aligned with the detector plane. In some examples, merging the CPM system into an intermediate configuration at 822 and / or shifting the conjugate deflector plane at 824 may include adjusting the focal length of one or more optical elements downstream of the deflector plane in any suitable manner as discussed above.

[0132] Entering the CPM system into an intermediate configuration at point 822 can be performed in any suitable manner to confirm that the detector plane is conjugate to the deflector plane. For example, and as mentioned above... Figure 3BAs discussed in the context, an intermediate configuration can refer to a configuration in which the beam spot (e.g., a beam spot that does not diffract a beam of charged particles and / or a beam spot characteristic of a diffracted beam pattern) at the detector plane is unfocused but substantially stationary when the beam blanker transitions between an unblanked state and a blanked state. Therefore, bringing the CPM system into an intermediate configuration at 822 may include defocusing the beam spot (or modulating the focus of the beam spot) until the CPM system reaches a configuration in which the beam spot is substantially stationary during operation of the beam blanker.

[0133] As a more specific example, and refer to Figure 8 Entering an intermediate configuration for the CPM system at 822 may include modulating the beam blanker between an unblanked and blanked state at 828 to move test beam pattern features in the detector plane. For example, modulating the beam blanker at 828 may include altering the deflection of the charged particle beam caused by the beam blanker, such as by changing and / or modulating the voltage applied to the electrostatic beam blanker. Test beam pattern features may include and / or may be any suitable features and / or combinations of features (e.g., spots, loops, disks, etc.) of the beam spot and / or pattern.

[0134] The beam blanking modulator at 828 may be repeatedly (e.g., periodically) executed and may include modulation to cause the beam blanking modulator to reach an unblanked state and / or a (fully) blanked state. Additionally or alternatively, the beam blanking modulator at 828 may be executed to cause the beam blanking modulator to transition between multiple states (but not including unblanked and / or fully blanked states).

[0135] Entering the intermediate configuration of the CPM system at 822 may also include adjusting one or more optical elements downstream of the deflector plane at 830 to fix the test beam pattern features to a position that is substantially stationary in the deflector plane during the modulation beam blanking at 828.

[0136] The beam blanking at 828 and the adjustment of the optics at 830 can be performed at least partially sequentially and / or at least partially simultaneously. For example, bringing the CPM system into an intermediate configuration at 822 may include modulating the beam blanking between an unblanked state and a blanked state to determine the degree to which the test beam pattern features are shifted in the detector plane during such modulation (e.g., by observing the test beam pattern features with the detector). This degree of shift can be characterized qualitatively and / or quantitatively, such as by manual observation and / or by measuring the fringe length associated with the fringe (e.g., Figure 4 The stripe length is 412). Then, bringing the CPM system into an intermediate configuration at 822 may include incrementally adjusting one or more optical elements to adjust the conjugate deflector plane (e.g., Figures 3A to 3CThe second conjugate deflector plane (342) is axially shifted, and the modulation beam blanking is repeated at 828 to determine whether the CPM system has reached an intermediate configuration. Specifically, the CPM system can be understood to be in an intermediate configuration when the test beam pattern features are observed to be substantially stationary in the detector plane during the modulation beam blanking at 828.

[0137] With the CPM system in an intermediate configuration, bringing the CPM system into a conjugate blanking configuration at 832 may include focusing the beam pattern onto the detector plane at 834, as described in the reference above. Figure 3C The manner described. For example, focusing the beam pattern at 834 may include adjusting one or more optical elements upstream of the deflector plane at 836 to bring the crossing plane of the charged particle beam to the detector plane. As a more specific example, adjusting the optical elements at 836 may include adjusting the focal length of source module optical elements (such as a gun lens) such that the diffraction plane of the charged particle beam is axially aligned with the detector plane. For example, when the focal length of the gun lens makes the focal plane of the charged particle beam (e.g., Figures 3A to 3C This configuration can be achieved when the first cross plane (330) is axially aligned with the deflector plane. Because the detector plane is conjugate to the deflector plane in the intermediate configuration, creating a beam cross in the deflector plane results in a corresponding cross in the detector plane. This cross plane at the detector plane can then correspond to the diffraction plane of the charged particle beam downstream of the sample, such that in the conjugate blanking configuration, the diffraction pattern is focused at the detector plane.

[0138] Any aspect of method 700 and / or method 800 may be performed at least partially automatically, such as via the controller of the CPM system (e.g., Figure 1 (Controller 150). For example, such a controller may be programmed and / or configured to receive images and / or corresponding signals from a detector, such as determining whether a detector plane is conjugate to a deflector plane and / or axially aligned with a cross plane, as described herein. Additionally or alternatively, the controller may be programmed and / or configured to control one or more optical elements of the CPM system, such as thereby changing the focal length of one or more electro-optic lenses and / or selectively deflecting a charged particle beam via a beam deflector. Additionally or alternatively, the controller may be programmed and / or configured to perform various methodological steps that are iteratively repeated to achieve a desired configuration, such as modulating a beam blanker at 828 and / or adjusting optical elements at 830.

[0139] Figure 9The following discussion is intended to provide a brief overview of an exemplary computing environment in which the disclosed techniques can be implemented. Specifically, some or all portions of this computing environment may be used with the methods and apparatus described above to, for example, configure a CPM system in a conjugate blanking configuration, focus a charged particle beam onto a sample, record diffraction patterns, and / or perform any portion of the methods disclosed above.

[0140] Although not required, the disclosed techniques are described in the general context of computer-executable instructions executed by a personal computer (PC), such as program modules. Typically, program modules include routines, programs, objects, components, data structures, etc., that perform specific tasks or implement specific abstract data types. Furthermore, the techniques disclosed herein can be implemented using other computer system configurations including: handheld devices, tablets, multiprocessor systems, microprocessor-based or programmable consumer electronics, network PCs, microcomputers, mainframes, virtual machines, containerized applications, Kubernetes clusters, etc. The disclosed techniques can also be practiced in distributed computing environments where tasks are performed on remote processing devices linked via a communication network. In a distributed computing environment, program modules can reside on both local and remote memory storage devices. In some cases, such processing is provided in a CPM system. The disclosed system can be used to control image acquisition and provides a user interface as well as act as an image processor.

[0141] refer to Figure 9 An exemplary system for implementing the disclosed technology includes a general-purpose computing device in the form of an exemplary conventional PC 900, the general-purpose computing device including one or more processing units 902, system memory 904, and a system bus 906 coupling various system components including the system memory 904 to the one or more processing units 902. The system bus 906 can be any of several types of bus structures, including a memory bus or memory controller, a peripheral device bus, and a local bus using any of the various bus structures. The exemplary system memory 904 includes read-only memory (ROM) 908 and random access memory (RAM) 910. A basic input / output system (BIOS) 912 is stored in the ROM 908, the BIOS containing basic routines that help transfer information between components within the PC 900.

[0142] The exemplary PC 900 also includes one or more storage devices 930, such as a hard disk drive for reading from and writing to a hard disk, a disk drive for reading from or writing to a removable disk, and an optical disc drive for reading from or writing to a removable optical disc (such as a CD-ROM or other optical media). Such storage devices may be connected to the system bus 906 via a hard disk drive interface, a disk drive interface, and an optical disc drive interface, respectively. The drives and their associated computer-readable media provide the PC 900 with non-volatile storage of computer-readable instructions, data structures, program modules, and other data. Other types of computer-readable media capable of storing data accessible by the PC, such as magnetic tape cartridges, flash memory cards, solid-state drives, digital video optical discs, CDs, DVDs, RAM, ROM, etc., may also be used in the exemplary operating environment.

[0143] Multiple program modules may be stored in storage device 930, including: an operating system, multiple operating systems, a virtual operating system, one or more applications, other program modules, and / or program data. In some examples, one or more aspects of the methods disclosed herein may be transferred to program modules via programming, implementation, coding, training, and / or otherwise, through machine learning, neural networks, artificial intelligence, etc.

[0144] The exemplary PC 900 may include various devices configured for a user interface. For example, a user may enter commands and information into the PC 900 via one or more input devices 940, such as a keyboard and / or pointing devices such as a mouse. For example, a user may enter commands to initiate image acquisition and / or initiate one or more methods disclosed herein. Other input devices may include digital cameras, microphones, joysticks, gamepads, buttons, dial pads, disc satellite antennas, scanners, etc. In some examples, several such input devices may be integrated into a single user interface device, such as those typically used in conjunction with a CPM system. These and other input devices are often connected to one or more processing units 902 via a serial port interface coupled to system bus 906, but may also be connected via other interfaces such as parallel ports, game ports, universal serial bus (USB), or wired or wireless network connections. Monitor 946 or other types of display devices are also connected to system bus 906 via an interface such as a video adapter and may display one or more images of a sample or specimen before, after, and / or during the execution of one or more methods disclosed herein. The monitor 946 can also be used to select the segment or specific image alignment and alignment procedure for processing, such as correlation, feature identification and preview area selection, or other image selection. Other peripheral output devices, such as speakers and printers (not shown), may be included.

[0145] PC 900 can operate in a networked environment using a logical connection to one or more remote computers (such as remote computer 960). In some examples, this includes one or more network or communication connections 950. Remote computer 960 can be another PC, server, router, network PC and / or peer device, or other common network node, and typically includes many or all of the elements described above regarding PC 900, although... Figure 9 Only storage device 862 is shown as an example. Personal computer 900 and / or remote computer 960 can be connected to a local area network (LAN) and / or wide area network (WAN). Such networking environments are common in offices, corporate computer networks, intranets, and the Internet.

[0146] like Figure 9 As shown, memory 990 (or a portion of such memory or other memory) may store processor-executable instructions for beam focusing control, beam deflector control, pattern recognition and analysis (e.g., to detect and / or characterize motion of beam features in the detector plane), etc. For example, such processor-executable instructions, when executed by a processor system, can cause PC900 and / or another component (e.g., Figure 1 CPM system 100 Figure 2 TEM 200 and / or Figures 3A to 3C (Any suitable component of the TEM 300) performs any of the methods disclosed herein. In some examples, processor-executable instructions may produce (e.g., processing of a recorded diffraction pattern) a display image, a preview image, and / or the acquisition of additional images.

[0147] General considerations As used in this application and claims, the singular forms “a,” “an,” and “the” include the plural forms unless the context clearly indicates otherwise. Additionally, the term “comprising” means “including.” Furthermore, the term “coupled” does not exclude the existence of intermediate elements between coupled items.

[0148] Unless otherwise stated, the term "substantially" as used herein means the listed values ​​and / or properties and any value and / or property that is at least 75% of the listed values ​​and / or properties. Equivalently, the term "substantially" means the listed values ​​and / or properties and any value and / or property that differs from the listed values ​​and / or properties by at most 25%. For example, "substantially equal" means quantities that are exactly equal and quantities that differ from each other by at most 25%.

[0149] The systems, apparatuses, and methods described herein should not be construed as limiting in any way. Rather, this disclosure relates to all novel and non-obvious features and aspects of the various disclosed examples, whether individually or in various combinations and sub-combinations formed with each other. The disclosed systems, methods, and apparatuses are not limited to any particular aspect or feature or combination thereof, nor are they required to possess any one or more particular advantages or problems solved. Any operational theory is provided for ease of interpretation, but the disclosed systems, methods, and apparatuses are not limited to such operational theories.

[0150] Although some of the methods disclosed are described in a specific order for ease of presentation, it should be understood that this descriptive approach includes rearrangement unless the specific language described below requires a particular order. For example, operations described sequentially may be rearranged or performed concurrently in some cases. Furthermore, for simplicity, the accompanying drawings may not show various ways in which the disclosed systems, methods, and apparatus can be combined with other systems, methods, and apparatuses. Additionally, this description sometimes uses terms such as “produce” and “provide” to describe the disclosed methods. These terms are high-level abstractions of the actual operations performed. The actual operations corresponding to these terms will vary depending on the specific implementation and can be readily identified by one of ordinary skill in the art.

[0151] In some examples, values, procedures, etc., may be characterized by qualifying terms such as “lowest,” “best,” “minimum,” “extreme,” etc. It should be understood that such descriptions are intended to indicate that a choice can be made among many alternative functionalities used, and that such a choice is not necessarily better, smaller, or otherwise more desirable than the other options.

[0152] Innovations can be described within the general context of computer-executable instructions, such as those instructions included in a program module and executed on a computing system targeting a real or virtual processor. Generally, a program module or component includes routines, programs, libraries, objects, classes, parts, data structures, etc., that perform a specific task or implement a specific abstract data type. The functionality of a program module can be combined or split among program modules as needed in various examples. The computer-executable instructions used in a program module can execute within a local or distributed computing system. Generally, a computing system or computing device can be local or distributed and can include any combination of dedicated hardware and / or general-purpose hardware with software that implements the functionality described herein. Examples of such computing systems or devices include personal computers, handheld devices, tablet computers, multiprocessor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, virtual machines, containerized applications, Kubernetes clusters, etc.

[0153] In the various examples described herein, modules (e.g., components or engines) may be "programmed" and / or "coded" to perform certain operations or provide certain functions, thereby instructing computer-executable instructions for the module to be executed to perform such operations, cause such operations to be performed, or otherwise provide such functions. While the functionality described with respect to a software component, module, or engine may be executed as a discrete software unit (e.g., a program, function, class method), it does not need to be implemented as a discrete unit. That is, the functionality may be incorporated into a larger or more general program, such as one or more lines of code within a larger or more general program.

[0154] The algorithms described may, for example, be embodied as software or firmware instructions executed by a digital computer. For instance, any of the disclosed methods may be executed by one or more of a computer or other computing hardware that is part of a microscopic examination tool. The computer may be a computer system comprising one or more processors (processing devices) and tangible, non-transitory computer-readable media (e.g., one or more optical discs, volatile memory devices such as DRAM or SRAM), or non-volatile memory or storage devices such as hard disk drives, NVRAM, and solid-state drives (e.g., flash drives)). The one or more processors may execute computer-executable instructions stored on one or more tangible, non-transitory computer-readable media, thereby performing any of the techniques disclosed. For example, software for performing any of the disclosed examples may be stored as computer-executable instructions on the one or more volatile, non-transitory computer-readable media, which, when executed by the one or more processors, cause the one or more processors to perform any of the disclosed techniques or subsets of techniques.

[0155] The principles of the disclosed techniques have been described and illustrated with reference to the illustrative examples. It should be recognized that the illustrated examples can be modified in arrangement and detail without departing from such principles. For example, an example element that performs in software may be implemented in hardware, and vice versa. Furthermore, techniques from any example can be combined with techniques described in any one or more other examples. It should be understood that programs and functions such as those described with reference to the illustrated examples can be implemented in a single hardware or software module, or separate modules may be provided. The specific arrangement described above is provided for ease of illustration, and other arrangements may be used.

[0156] Additional embodiments of the disclosed technology In view of the above specific implementations of the disclosed subject matter, this application discloses further embodiments listed below. It should be noted that a feature of a single example or a combination thereof, or one or more features of an example optionally used in combination with one or more features of one or more other examples, are also further examples of the disclosure of this application.

[0157] Example 1. A method of operating a charged particle microscopy (CPM) system including a beam deflector positioned at a deflector plane, the CPM system being configured to guide a beam of charged particles to a sample to produce a diffraction beam pattern at a diffraction plane, the method comprising: adjusting one or more optical elements of the CPM system such that the deflector plane is conjugate to the diffraction plane; and recording the diffraction beam pattern by means of a detector positioned at the diffraction plane.

[0158] Example 2. The method according to Example 1, wherein adjusting the one or more optical elements includes adjusting the position of the diffraction plane to align the diffraction plane with the detector axis.

[0159] Example 3. According to the method of Example 2, the CPM system includes a first optical component positioned upstream of the deflector plane and a second optical component positioned downstream of the deflector plane, wherein adjusting the position of the diffraction plane includes adjusting one or more optical elements of the second optical component.

[0160] Example 4. The method according to Example 3, wherein the method further includes adjusting one or more optical elements of the first optical assembly to align the cross plane of the charged particle beam with the detector axis.

[0161] Example 5. The method according to any one of Examples 3 to 4, wherein adjusting the one or more optical elements of the first optical component is performed after adjusting the one or more optical elements of the second optical component.

[0162] Example 6. The method according to any one of Examples 3 to 5, wherein the adjustment of the one or more optical elements of the first optical component is performed before the adjustment of the one or more optical elements of the second optical component.

[0163] Example 7. The method according to any one of Examples 3 to 6, wherein the CPM system is configured to generate a modulation beam pattern at the detector, and wherein adjusting the one or more optical elements of the second optical assembly includes adjusting such that the modulation beam pattern becomes increasingly unfocused at the detector.

[0164] Example 8. The method according to any one of Examples 3 to 7, wherein adjusting the one or more optical elements of the first optical assembly includes adjusting the first focal length associated with the first optical assembly.

[0165] Example 9. The method according to Example 8, wherein adjusting the one or more optical elements of the second optical component includes adjusting the second focal length associated with the second optical component.

[0166] Example 10. The method according to any one of Examples 7 to 9, wherein adjusting one or both of the first focal length and adjusting the second focal length includes adjusting the excitation voltage applied to the electro-optic lens.

[0167] Example 11. The method according to any one of Examples 3 to 10, wherein the CPM system includes a source optics assembly configured to accelerate the charged particle beam toward the sample, and wherein the first optical assembly includes at least a portion of the source optics assembly.

[0168] Example 12. The method according to any one of Examples 3 to 11, wherein the second optical component comprises at least a portion of the concentrator optics component of the CPM system.

[0169] Example 13. The method according to any one of Examples 3 to 12, wherein the second optical component comprises at least a portion of the objective lens optical component.

[0170] Example 14. The method according to any one of Examples 3 to 13, wherein adjusting the one or more optical elements of the second optical assembly includes adjusting one or more optical elements positioned downstream of the sample.

[0171] Example 15. The method according to any one of Examples 3 to 14, wherein the second optical component comprises one or more objective lens elements.

[0172] Example 16. The method according to any one of Examples 3 to 15, wherein adjusting the position of the diffraction plane includes shifting the position of the diffraction plane in the axial direction.

[0173] Example 17. The method according to any one of Examples 1 to 16, wherein the diffraction beam pattern comprises a diffraction pattern.

[0174] Example 18. The method according to any one of Examples 1 to 17, the method further comprising operating the beam deflector to guide the charged particle beam to the sample in the form of a beam pulse having a variable beam pulse duration, and changing the beam pulse duration to perform a time-resolved diffraction study of the sample.

[0175] Example 19. The method according to any one of Examples 1 to 18, wherein the CPM system is configured such that when the beam deflector is in an unblanked state, the charged particle beam is at least substantially not deflected by the beam deflector, wherein the beam deflector is configured to selectively deflect the charged particle beam away from the sample when the beam deflector is in a fully blanked state, wherein the beam deflector is configured to guide the charged particle beam along a trajectory that generates a partially blanked beam pattern at the diffraction plane when the beam deflector is in any of a plurality of partially blanked states defined between the unblanked state and the fully blanked state, and wherein the method includes operating the CPM system such that when the beam deflector transitions from the unblanked state to the fully blanked state, the partially blanked beam pattern is substantially stationary in the deflector plane.

[0176] Example 20. The method according to any one of Examples 1 to 19, wherein when the sample is positioned in the beam path of the charged particle beam, the adjustment of one or more optical elements of the CPM system is performed at least in part.

[0177] Example 21. The method according to any one of Examples 1 to 20, wherein when the sample is removed from the beam path of the charged particle beam, the adjustment of one or more optical elements of the CPM system is performed at least in part.

[0178] Example 22. A method of operating a charged particle microscopy (CPM) system, the method comprising: guiding a charged particle beam to a sample, the sample modulating the charged particle beam to create a beam pattern downstream of the sample; switching a beam blanking device of the CPM system positioned at a deflector plane between an un-blinded state and a blanked state, in the un-blinded state the charged particle beam reaches the sample, and in the blanked state the charged particle beam is guided away from the sample; and recording the beam pattern by a detector positioned at a detector plane conjugate to the deflector plane, wherein the beam pattern includes one or more beam pattern features focused in the detector plane, and wherein the one or more beam pattern features are substantially stationary in the detector plane as the beam blanking device switches between the un-blinded state and the blanked state.

[0179] Example 23. The method according to Example 22, wherein the beam blanking device includes an electrostatic beam blanking device.

[0180] Example 24. The method according to any one of Examples 22 to 23, wherein the beam blanker is switched between the unblanked state and the blanked state within a time period of less than 10 nanoseconds (ns).

[0181] Example 25. The method according to any one of Examples 22 to 24, the method further comprising configuring the CPM system in a conjugate blanking configuration, wherein the deflector plane is conjugate to the detector plane, and wherein the cross-position of the charged particle beam is located at the deflector plane, and wherein configuring the CPM system comprises: bringing the CPM system into an intermediate configuration, wherein the detector plane is conjugate to the deflector plane; and after bringing the CPM system into the intermediate configuration, bringing the CPM system into the conjugate blanking configuration.

[0182] Example 26. The method according to Example 25, wherein configuring the CPM system to the conjugate blanking configuration is performed at least in part before directing the charged particle beam to the sample.

[0183] Example 27. The method according to any one of Examples 25 to 26, wherein configuring the CPM system to the conjugate blanking configuration is performed at least in part after the charged particle beam is directed to the sample.

[0184] Example 28. The method according to any one of Examples 25 to 27, wherein bringing the CPM system into the intermediate configuration includes shifting the conjugate deflector plane to axial alignment with the detector plane.

[0185] Example 29. The method according to any one of Examples 25 to 28, wherein bringing the CPM system into the intermediate configuration includes adjusting the focal length of one or more optical elements downstream of the deflector plane.

[0186] Example 30. The method according to any one of Examples 25 to 29, wherein bringing the CPM system into the intermediate configuration comprises: modulating the beam blanker between the unblanked state and the blanked state to move a test beam pattern feature among the one or more beam pattern features in the detector plane; and adjusting one or more optical elements downstream of the deflector plane to fix the test beam pattern feature to a substantially stationary position in the deflector plane during modulation of the beam blanker between the unblanked state and the blanked state.

[0187] Example 31. The method according to Example 30, wherein modulating the beam blanker and adjusting the one or more optical elements downstream of the deflector plane are performed at least partially simultaneously.

[0188] Example 32. The method according to any one of Examples 25 to 31, wherein bringing the CPM system into the conjugate blanking configuration includes focusing the beam pattern onto the detector plane when the CPM system is in the intermediate configuration.

[0189] Example 33. The method according to Example 32, wherein focusing the beam pattern includes adjusting one or more optical elements upstream of the deflector plane to bring the crossing plane of the charged particle beam to the detector plane.

[0190] Example 34. The method according to any one of Examples 32 to 33, wherein focusing the beam pattern onto the detector plane includes adjusting the focal length of one or more optical elements upstream of the deflector plane.

[0191] Example 35. The method according to any one of Examples 18 to 34, the method further comprising operating the beam blanker to guide the charged particle beam to the sample in the form of a beam pulse having a variable beam pulse duration, and changing the beam pulse duration to perform a time-resolved diffraction study of the sample.

[0192] Example 36. A charged particle microscopy (CPM) system comprising: a charged particle source configured to emit charged particles toward a sample along an optical axis; a first optical assembly positioned downstream of the charged particle source and configured to change the axial position of the focal plane of the charged particle beam upstream of the sample; a beam deflector positioned at a deflector plane downstream of the first optical assembly and configured to selectively deflect the charged particle beam away from the sample; a second optical assembly positioned downstream of the deflector plane; and a detector positioned at a detector plane downstream of the second optical assembly, wherein the CPM system is configured such that the charged particle beam exhibits beam crossing at the deflector plane and such that the deflector plane is imaged onto the detector.

[0193] Example 37. The CPM system according to Example 36, wherein the first optical component includes a gun lens configured to adjust the axial position of the beam crossover, and wherein the CPM system is configured such that the gun lens remains in a fixed excitation during operation of the CPM system.

[0194] Example 38. The CPM system according to any one of Examples 36 to 37, wherein the second optical component includes one or both of a condenser optics assembly and an objective lens optics assembly.

[0195] Example 39. The CPM system according to any one of Examples 36 to 38, wherein one or more components of the second optical component are positioned downstream of the sample.

[0196] Example 40. The CPM system according to any one of Examples 36 to 39, the CPM system further comprising a blanking aperture, wherein the beam deflector is configured to selectively guide the charged particle beam so as to be blocked by the blanking aperture.

[0197] Example 41. The CPM system according to Example 40, wherein the second optical component includes the blanking aperture.

[0198] Example 42. A CPM system according to any one of Examples 36 to 41, wherein the beam deflector is configured to guide the charged particle beam to the sample in the form of a beam pulse having a variable beam pulse duration to perform a time-resolved diffraction study of the sample.

[0199] Unless otherwise stated, features described herein with respect to any embodiment may be combined with other features described in any one or more other embodiments. For example, any one or more steps and / or features of a method may be combined with any one or more steps and / or features of another method.

[0200] Given that the principles of this disclosure can be applied in many possible ways, it should be recognized that the illustrated configurations depict examples of the disclosed technology and should not be considered as limiting the scope of this disclosure or the claims. Rather, the scope of the claimed subject matter is defined by the following claims and their equivalents.

Claims

1. A method of operating a charged particle microscope (CPM) system comprising a beam deflector positioned at a deflector plane, the CPM system configured to direct a charged particle beam to a sample to produce a diffraction beam pattern at a diffraction plane, the method comprising: adjusting one or more optical elements of the CPM system to cause the deflector plane to be conjugate with the diffraction plane; and recording the diffraction beam pattern by a detector positioned at the diffraction plane.

2. The method of claim 1, wherein adjusting the one or more optical elements comprises adjusting a position of the diffraction plane to cause the diffraction plane to be axially aligned with the detector.

3. The method of claim 2, wherein the CPM system comprises a first optical assembly positioned upstream of the deflector plane and a second optical assembly positioned downstream of the deflector plane, wherein adjusting the position of the diffraction plane comprises adjusting one or more optical elements of the second optical assembly, and wherein the method further comprises adjusting one or more optical elements of the first optical assembly to cause a cross-plane of the charged particle beam to be axially aligned with the detector.

4. The method of claim 3, wherein adjusting the one or more optical elements of the first optical assembly is performed after adjusting the one or more optical elements of the second optical assembly.

5. The method of claim 3, wherein adjusting the one or more optical elements of the first optical assembly comprises adjusting a first focal length associated with the first optical assembly, and wherein adjusting the one or more optical elements of the second optical assembly comprises adjusting a second focal length associated with the second optical assembly.

6. The method of claim 3, wherein the CPM system comprises a source optics assembly configured to accelerate the charged particle beam toward the sample, and wherein the first optical assembly comprises at least a portion of the source optics assembly.

7. The method of claim 3, wherein the second optical assembly comprises at least a portion of a condenser optics assembly of the CPM system.

8. The method of claim 3, wherein the second optical assembly comprises at least a portion of an objective optics assembly.

9. The method of claim 3, wherein adjusting the position of the diffraction plane comprises shifting the position of the diffraction plane in an axial direction. ​ 10. The method of claim 1, wherein the CPM system is configured such that when the beam deflector is in an unblanked state, the charged particle beam is at least substantially not deflected by the beam deflector, wherein the beam deflector is configured to selectively deflect the charged particle beam away from the sample when the beam deflector is in a fully blanked state, wherein the beam deflector is configured to direct the charged particle beam along a trajectory that produces a partially blanked beam pattern at the diffraction plane when the beam deflector is in any of a plurality of partially blanked states defined between the unblanked state and the fully blanked state, and wherein the method comprises operating the CPM system such that when the beam deflector transitions from the unblanked state to the fully blanked state, the partially blanked beam pattern is substantially stationary in the deflector plane.

11. A method of operating a charged particle microscope (CPM) system, the method comprising: directing a charged particle beam to a sample, the sample modulating the charged particle beam to create a beam pattern downstream of the sample; transitioning a beam blanker of the CPM system positioned at a deflector plane between an unblanked state in which the charged particle beam reaches the sample and a blanked state in which the charged particle beam is directed away from the sample; and recording the beam pattern by a detector positioned at a detector plane that is conjugate to the deflector plane, wherein the beam pattern comprises one or more beam pattern features that are focused in the detector plane, and wherein the one or more beam pattern features are substantially stationary in the detector plane when the beam blanker transitions between the unblanked state and the blanked state.

12. The method of claim 11, wherein transitioning the beam blanker between the unblanked state and the blanked state is performed in a time period of less than 10 nanoseconds (ns).

13. The method of claim 11, further comprising configuring the CPM system into a conjugate blanking configuration, wherein the deflector plane is conjugate to the detector plane, and wherein a cross-over of the charged particle beam is positioned at the deflector plane, and wherein configuring the CPM system comprises: entering the CPM system into an intermediate configuration in which the detector plane is conjugate to the deflector plane; and entering the CPM system into the conjugate blanking configuration after entering the CPM system into the intermediate configuration.

14. The method of claim 13, wherein entering the CPM system into the intermediate configuration comprises adjusting a focal length of one or more optical elements downstream of the deflector plane.

15. The method of claim 13, wherein entering the CPM system into the intermediate configuration comprises: modulating the beam blanker between the unblanked state and the blanked state to move a test beam pattern feature of the one or more beam pattern features in the detector plane; and adjusting one or more optical elements downstream of the deflector plane to fix the test beam pattern features to a position that is substantially stationary in the deflector plane during modulation of the beam blanker between the unblanked state and the blanked state.

16. The method of claim 13, wherein entering the CPM system into the conjugate blanking configuration comprises focusing the beam pattern to the detector plane with the CPM system in the intermediate configuration.

17. The method of claim 16, wherein focusing the beam pattern to the detector plane comprises adjusting a focal length of one or more optical elements upstream of the deflector plane.

18. A charged particle microscope (CPM) system, comprising: a charged particle source configured to emit a charged particle beam along an optical axis toward a sample; a first optical assembly positioned downstream of the charged particle source and configured to change an axial position of a focal plane of the charged particle beam upstream of the sample; a beam deflector positioned at a deflector plane downstream of the first optical assembly and configured to selectively divert the charged particle beam away from the sample; a second optical assembly positioned downstream of the deflector plane and configured to change an axial position of a focal plane of the charged particle beam downstream of the sample; and a detector positioned at a detector plane downstream of the second optical assembly, wherein the CPM system is configured such that the charged particle beam exhibits a beam crossover at the deflector plane, and such that the deflector plane is imaged onto the detector.

19. The CPM system of claim 18, wherein the first optical assembly comprises a gun lens configured to adjust an axial position of the beam crossover, and wherein the CPM system is configured such that the gun lens remains at a fixed excitation during operational use of the CPM system.

20. The CPM system of claim 18, wherein the second optical assembly comprises one or both of a condenser optics assembly and an objective optics assembly.

21. The CPM system of claim 18, wherein one or more components of the second optical assembly are positioned downstream of the sample.

22. The CPM system of claim 18, further comprising a blanking aperture, wherein the beam deflector is configured to selectively direct the charged particle beam so as to be blocked by the blanking aperture.

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