Method and system for collection of electron diffraction data from a particle region

Abstract

Provided herein is a method for obtaining electron diffraction, ED, data from a sample (100) using an electron microscope, EM, having an EM beam, the sample (100) containing a particle region (110) comprising one particle (112) or a cluster of multiple particles (112), the method comprising steps: receiving a two-dimensional intensity map, 2D intensity map (200), from the sample (100) using the EM, wherein the 2D intensity map (200) contains a region 2D intensity map (210) corresponding to the particle region (110); determining, from the region 2D intensity map (210), a region perimeter (310); determining from the region 2D intensity map (210) one or more beam target locations (420 a to d) corresponding to one or more locations (320 a to d), perimeter locations, only on the region perimeter (310); acquiring electron diffraction, ED, data from the particle region (110), using the EM; wherein during the acquiring of ED data from the particle region (110) the EM beam is activated only at the one or more beam target locations (420 a to d).

Description

[0001] METHOD AND SYSTEM FOR COLLECTION OF ELECTRON DIFFRACTION DATA FROM A PARTICLE REGION

[0002] Field of the invention

[0003] The present disclosure is in a field of collection of electron diffraction data using a charged particle (electron) microscope.

[0004] Background to the invention

[0005] Obtaining electron diffraction data with a charged particle microscope uses an incident charged particle beam (electron microscope, EM, beam) that passes through the sample. If the beam passes through the sample, the electrons interfere to generate an electron diffraction, ED, pattern captured by a detector array. During acquisition of data, the EM beam is scanned across the sample, for instance, in a raster scan. Large quantities of ED data are collected, typically one frame per location of the EM beam. Because of interaction between the electron beam and the sample, the sample suffers beam damage, and ED data collected towards the end of the acquisition no longer reflects the initial state of the sample; the sample is effectively contaminated due to growth of carbon on the beam- exposed sample, leading to distortion and less reliable data. It also means that the sample cannot be used anymore for subsequent analysis. Furthermore, a large amount of data is quickly generated, increasing requirements for hardware that can manage the speed of data transfer, that can process the data, and for data storage.

[0006] It is an aim of the present invention to reduce sample contamination during acquisition and reduce hardware and other resources needed to store and / or process the collected ED data.

[0007] Summary of the invention

[0008] Provided herein is a method for obtaining electron diffraction, ED, data from a sample (100) containing a particle region (110) comprising one particle (112) or a cluster of multiple particles (112), the method comprising:

[0009] - obtaining a two-dimensional intensity map, 2D intensity map (200), from the sample (100) using an electron microscope, EM, wherein the 2D intensity map (200) contains a region 2D intensity map (210) corresponding to the particle region (110); - determining, from the region 2D intensity map (210), a region perimeter (310);

[0010] - acquiring electron diffraction, ED, data from the particle region (110), using the EM wherein a beam of the EM is activated only at one or more beam target locations (420 a to d) on the particle region (110) corresponding to one or more locations (320 a to d), perimeter locations, only on the region perimeter (310).

[0011] Further provided is a (computer-implemented) method for obtaining electron diffraction, ED, data from a sample (100) using an electron microscope, EM, having an EM beam, the sample (100) containing a particle region (110) comprising one particle (112) or a cluster of multiple particles (112), the method comprising steps:

[0012] - receiving a two-dimensional intensity map, 2D intensity map (200), from the sample (100) using the EM, wherein the 2D intensity map (200) contains a region 2D intensity map (210) corresponding to the particle region (110);

[0013] - determining, from the region 2D intensity map (210), a region perimeter (310);

[0014] - determining from the region 2D intensity map (210) one or more beam target locations (420 a to d) corresponding to one or more locations (320 a to d), perimeter locations, only on the region perimeter (310),

[0015] - acquiring electron diffraction, ED, data from the particle region (110), using the EM.

[0016] During the acquiring of ED data from the particle region (110) the EM beam is activated only at the one or more beam target locations (420 a to d).

[0017] In particular, during the method, a beam of the EM beam for acquiring (the) ED data is activated only at the one or more beam target locations (420 a to d) on the particle region (110) corresponding to one or more locations (320 a to d), perimeter locations, only on the region perimeter (310).

[0018] In particular, during the method, the EM beam for acquiring (the) ED data is not activated at any location that is not a beam target location (420 a to d) on the particle region (110) corresponding to one or more locations (320 a to d), perimeter locations.

[0019] According a preferred aspect:

[0020] - the region perimeter (310) is represented in a 2D region perimeter map (300) by a first indicator disposed at locations of the map (300) corresponding to the region perimeter (310), - all other regions of 2D region perimeter map (300) are represented by a second indicator different from the first indicator, and

[0021] - during the acquiring of ED data from the particle region (110c), the beam of the electron microscope, EM beam, is activated only at one or more beam target locations (420 a to d) of the particle region (110c) corresponding to one or more perimeter locations (320 a to d) having the first indicator in the 2D region perimeter map (300).

[0022] According a preferred aspect:

[0023] - the region perimeter (310) is represented in a 2D region perimeter map (300) by a first indicator disposed at locations of the map (300) corresponding to the region perimeter (310),

[0024] - all other regions of 2D region perimeter map (300) are represented by a second indicator different from the first indicator,

[0025] - during the method, the EM beam for acquiring (the) ED data is activated only at one or more beam target locations (420 a to d) of the particle region (110c) corresponding to one or more perimeter locations (320 a to d) having the first indicator in the 2D region perimeter map (300).

[0026] According another preferred aspect the region perimeter (310) is determined from the region 2D intensity map (210) using image processing and edge detection, wherein the region perimeter (310) is determined from the detected edge.

[0027] According another preferred aspect a quantity of perimeter locations (320 a to d) is greater than 1 , and perimeter locations (320 a to d) are randomly selected, or selected according to a rule.

[0028] According another preferred aspect the activated beam has a beam dose at the beam target location (420 a to d) of 0.01 electron per angstrom2per second to 8 x 106electron per angstrom2per second.

[0029] According another preferred aspect, during obtaining ED data, the EM beam is deactivated during repositioning between two spatially distinct beam target locations (420 a to d). According another preferred aspect, during obtaining ED data, the EM beam is continuously activated during repositioning between two adjacently-located beam target locations (420 a to d).

[0030] According another preferred aspect, during the obtaining ED data, the EM beam is moved in a scan pattern, such as a raster scan, snake-pattern scanning, or random position scanning, and the EM beam is deactivated during repositioning between two spatially separated beam target locations (420 a to d).

[0031] According another preferred aspect, during the obtaining ED data, the EM beam is moved in a path corresponding to the region perimeter (310), and the EM beam is continuously activated during repositioning between beam target locations (420 a to d).

[0032] According another preferred aspect at least some or all of the beam target locations (420 a to d) is visited:

[0033] - only once by the EM beam during a data collection session, or

[0034] - at least twice by the EM beam during a data collection session.

[0035] Further provided is a (computer-implemented) (control) method of controlling an electron microscope, EM, to carry out a method as described herein.

[0036] According another preferred aspect the (control) method comprises

[0037] - sending instructions to the EM to obtain the two-dimensional intensity map, 2D intensity map (200), from the sample (100), wherein the 2D intensity map (200) contains the region 2D intensity map (210) corresponding to the particle region (110);

[0038] - sending instructions to the EM to acquire the electron diffraction, ED, data from the particle region (110), wherein a beam of the EM is instructed to be activated only at one or more beam target locations (420 a to d) of the particle region (110) corresponding to one or more locations (320 a to d) on only a region perimeter (310), wherein the region perimeter (310) is determined from the region 2D intensity map (210).

[0039] Further provided is a computing device or system configured for performing the (control) method as described herein. Further provided is a computer program or computer program product having instructions which when executed by a computing device or system cause the computing device or system to perform the (control) method as described herein.

[0040] Further provided is a computer readable medium having stored thereon a computer program (product) having instructions which when executed by a computing device or system cause the computing device or system to perform the (control) method as described herein.

[0041] Further provided is an electron microscope, EM, having an EM beam and a processor adapted to execute the steps of the method as described herein.

[0042] Further provided is a computer implemented method for obtaining electron diffraction, ED, data from a sample (100) using an electron microscope, EM, having an EM beam, the sample (100) containing a particle region (110) comprising one particle (112) or a cluster of multiple particles (112), the method comprising steps:

[0043] - outputting instructions for the EM for acquiring a two-dimensional intensity map, 2D intensity map (200), from the sample (100), wherein the 2D intensity map (200) contains a region 2D intensity map (210) corresponding to the particle region (110);

[0044] - receiving the two-dimensional intensity map, 2D intensity map (200) from the EM;

[0045] - determining from the region 2D intensity map (210), a region perimeter (310);

[0046] - determining from the region 2D intensity map (210) one or more beam target locations (420 a to d) corresponding to one or more locations (320 a to d), perimeter locations, only on the region perimeter (310),

[0047] - outputting instructions for the EM for acquiring the ED data from the particle region (110), wherein the instructions for acquiring (the) ED data indicate activation of the EM beam only at the one or more beam target locations (420 a to d).

[0048] Further provided is a computing device or system configured for performing the method as described herein.

[0049] Further provided is a computer program or computer program product having instructions which when executed by a computing device or system cause the computing device or system to perform the method as described herein. Further provided is a computer readable medium having stored thereon a computer program (product) having instructions which when executed by a computing device or system cause the computing device or system to perform the method as described herein.

[0050] Figure Legends

[0051] FIG. 1 is a schematic example of a particle region on a support.

[0052] FIG. 2 is a 2D intensity map of the sample of FIG. 1 , representing for example height (relief) of the particle region.

[0053] FIG. 3 is a schematic example of a particle perimeter determined from the intensity map of FIG. 2, and a plurality of perimeter locations.

[0054] FIG. 4 shows the particle region of FIG. 1 , and a plurality of beam target locations, each corresponding to a perimeter location of FIG. 3.

[0055] FIG. 5 shows an experimentally determined intensity map of a particle region of Lithium iron phosphate (LiFePO4).

[0056] FIG. 6 shows a particle perimeter determined from the intensity map of FIG. 5

[0057] FIG. 7 shows a particle perimeter of FIG. 6, and a plurality of perimeter locations.

[0058] FIG. 8 shows the intensity map of FIG. 5, and a plurality of beam target locations, each corresponding to a perimeter locations of FIG. 7, and additionally 2 negative control perimeter locations.

[0059] FIG. 9A to 9E show different ED patterns from each of beam target locations 420v, 420w, 420x, 422a and 422b of FIG. 8 respectively.

[0060] FIG. 10 is a schematic illustration of a principle of the present disclosure demonstrating a thinning of the particle region at the edges for a particle region made up from a cluster of multiple particles.

[0061] FIG. 11 is a schematic illustration of a principle of the present disclosure demonstrating a thinning of the particle region at the edges for a particle region made up from a single particle.

[0062] Detailed description of invention

[0063] Before the present system and method of the invention are described, it is to be understood that this invention is not limited to particular systems and methods or combinations described, since such systems and methods and combinations may, of course, vary. It is also to be understood that the terminology used herein is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims. As used herein, the singular forms "a", "an", and "the" include both singular and plural referents unless the context clearly dictates otherwise.

[0064] The terms "comprising", "comprises" and "comprised of" as used herein are synonymous with "including", "includes" or "containing", "contains", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. It will be appreciated that the terms "comprising", "comprises" and "comprised of" as used herein comprise the terms "consisting of', "consists" and "consists of".

[0065] The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within the respective ranges, as well as the recited endpoints.

[0066] The term "about" or “approximately” as used herein when referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of + / -10% or less, preferably + / -5% or less, more preferably + / -1 % or less, and still more preferably + / -0.1 % or less of and from the specified value, insofar such variations are appropriate to perform in the disclosed invention. It is to be understood that the value to which the modifier "about" or “approximately” refers is itself also specifically, and preferably, disclosed.

[0067] Whereas the terms “one or more” or “at least one”, such as one or more or at least one member(s) of a group of members, is clear per se, by means of further exemplification, the term encompasses inter alia a reference to any one of said members, or to any two or more of said members, such as, e.g., any >3, >4, >5, >6 or >7 etc. of said members, and up to all said members.

[0068] All references cited in the present specification are hereby incorporated by reference in their entirety. In particular, the teachings of all references herein specifically referred to are incorporated by reference.

[0069] Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention. In the following passages, different aspects of the invention are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

[0070] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the appended claims, any of the claimed embodiments can be used in any combination.

[0071] In the present description of the invention, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration only of specific embodiments in which the invention may be practiced. Parenthesized or emboldened reference numerals affixed to respective elements merely exemplify the elements by way of example, with which it is not intended to limit the respective elements. Unless otherwise indicated, all figures and drawings in this document are not to scale and are chosen for the purpose of illustrating different embodiments of the invention. In particular the dimensions of the various components are depicted in illustrative terms only, and no relationship between the dimensions of the various components should be inferred from the drawings, unless so indicated.

[0072] It is to be understood that other embodiments may be utilised and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims. Provided herein is a method for obtaining electron diffraction, ED, data from a sample (100) containing at least one particle region (110) comprising one or more particles (112). The method comprises obtaining or receiving (by a computer device, computer system or computer processor) a two-dimensional intensity map, 2D (two dimensional) intensity map (200), from the sample (100) using an electron microscope, EM. The 2D intensity map (200) contains a region 2D intensity map (210) corresponding to the particle region (110) or the part thereof. A particle perimeter (320) is determined from the region 2D intensity map (210). Electron diffraction, ED, data ( / .e. an ED pattern) is acquired from the particle region (110), wherein a beam of the electron microscope is activated only at one or more beam target locations (420 a to d) of the particle region (110) corresponding to one or more locations (320 a to d), perimeter locations, on the particle perimeter (310).

[0073] The primary effect of the present disclosure is a prediction of locations on the sample region at which meaningful ED data is most likely to be obtained, namely where electrons can transmit through the sample at a given electron beam accelerating voltage. The inventors have exploited a property of a particle region in that its outermost edge is typically thinner than its centre. They found that if the EM beam is restricted to one or more target locations on the particle perimeter where the sample is thinner the ED data obtained contains meaningful information, and compared with when the EM beam is scanned over the whole sample or scanned over a portion of the sample, beam damage is reduced, sample contamination is reduced, and the hardware and other resources required to process the collected data are reduced.

[0074] FIG. 10 illustrates a particle region (110) comprising a plurality of particles (112) in a particle region (110) on a support (120), and FIG. 11 illustrates a particle region (110) comprising only one particle (112) in a particle region (110) on a support (120). Different discrete locations of the EM beam (150 arrows) before the particle region (110). The particle region (110) thins in zones ZA and ZC. The EM beam (150) located in zones ZA and ZC interact with periphery portions of the sample region and pass through (155) to generate ED data. Those EM beams (150) located in zone ZB are more hindered in passing through because the energy of the EM beam is too low. Hence, with the present disclosures, target location dose can be sufficiently low to pass through the particle region (110) periphery to generate ED data representative of the whole sample region. The majority of the particle region (zone ZB) is not exposed to the EM beam, hence the combination of low target location dose and restriction of possible beam target locations of the particle region greatly reduce sample contamination, leading to improved data reliability. The effects are summarised below: reduced dose per beam target location (target location dose) because each beam target location is thinner; more thicker sample locations typically within the region perimeter, require a higher dose; reduced dose per particle region (region dose) because the EM beam only visits locations on the particle perimeter, which has fewer possible locations compared with visiting the whole particle area; the fewer locations and captured ED patterns means less data is generated over time, hence less hardware and / or other resources are needed to process and / or store the collected ED data; a majority of the particle region is not exposed to the EM beam, reducing contamination, so the particle region and / or sample can be used for subsequent analysis, beam kinetic energy may be reduced because only the thinner parts of the sample region are investigated. A lower EM accelerator voltage of e.g. 1 to 100 keV may be built for this purpose, which reduces the cost of instrument.

[0075] - with a reduced voltage instrument, there is less complexity for an operator, hence, it becomes cheaper to provide a service to more industries and institutions, acquisition is fast because the beam of the electron microscope during acquisition is positioned only at one or more perimeter locations within the particle perimeter, and is not raster-scanned across an entirety of the particle. The speed allows ED patterns from multiple particles contained within same sample to be rapidly acquired. data storage is minimized as no data is stored from areas that are not at one or more perimeter locations (320 a to d) on the region perimeter (320). The data that is stored provides similar information compared with when the ED beam is scanned across the whole sample region.

[0076] The sample (100) comprises one or more particle regions (110). A particle region (110) is a continuous region of the sample occupied by one or more particles under investigation.

[0077] A particle region (110) may be made up from a cluster or aggregate of multiple particles (112) (see, for instance, FIG. 10). In a cluster or aggregate, the particles are disposed adjacently and / or overlapping and / or stacked. Alternatively, a particle region (110) may be made up from only one particle (112) (see, for instance, FIG. 11).

[0078] The sample (100) may contain only one particle region, in which case the methods described herein are applied to the one particle region, and the ED data of the sample contains ED data of the one particle region. It is within the scope of the present disclosure that the sample contains multiple particle regions, in which case the methods described herein are applied one particle region at a time. The ED data of the sample may contain ED data of the one particle region or of multiple particle regions.

[0079] The one or more particle regions (110) are disposed on a support (120) suitable for acquisition of the 2D intensity map (200), region 2D intensity map, and of the ED data. The support typically has a flat or planar surface on which the one or more particle regions (110) is disposed. The support is typically rigid. Examples of suitable support substrates include silicon nitride, silicon dioxide, amorphous carbon films, cellulose-based films, graphene or other 2D materials. The support substrate may contain holes above which the sample particles can be partially suspended. The sample may be prepared according to standard techniques.

[0080] The 2D intensity map (200) is obtained of at least a part of, preferably a whole of the sample (100) by the EM. The 2D intensity map (200) is a representation of at least a part (or all) of the sample (100) comprising an indication of at least a part of an outer edge of each particle region (110) as a function of 2D space (x,y) occupied by the sample (100). The outer edge of a particle in the sample may be determined against the substrate background and / or within a vacuum. It is typically represented as a 2D colour or 2D greyscale image. It may alternatively or additionally be represented as a set of coordinates and intensities. The two-dimensional intensity map, 2D intensity map (200) is received by a computer device, computer system or computer processor.

[0081] The intensity of the 2D intensity map (200) is representative of a presence and absence of at least an outer edge of a particle region (110). It may additionally represent sample or particle region height, density or charge. Generally speaking, the 2D intensity map (200) provides a contrast between particle region and background.

[0082] The 2D intensity map (200) is representative of a collected signal (e.g. one or more of elastically scattered electrons (electrons from the primary incident electron beam that interacted elastically with the sample and / or the support), SE (SE: secondary electrons, electrons originating from inelastic scattering of the primary electrons within the sample), BSE (BSE: backscattered electrons, electrons originating from elastic scattering of the primary electrons within the sample), X-rays, Auger electrons, photons) as a function of x,y beam position), which the sample (100) causes (e.g. by emission, reflection, generation, absorption) due to its interaction with electron beam.

[0083] There is a plurality of known 2D intensity maps in the art comprising an indication of at least a part of an outer edge of a particle region (110) as a function of the 2D space (x,y) occupied by the sample (100). The 2D intensity map (200) may contain information on one or more of: height, density, thickness (z), or atomic weight / number (Z), crystal orientation, charge, strain local fields, amorphous content, or crystallinity as a function of the 2D space (x,y) occupied by the sample (100). Preferably, the 2D intensity map (200) contains information of sample height, density, or thickness (z). A charge map provides information about local electrostatic potential distribution and charge density along the sample. A strain local fields map refers to the deformation or distortion of the crystal lattice structure on a small, localized scale. Strain can arise due to various factors, including mechanical forces, temperature changes, or the presence of defects. Amorphous content map shows the regions where only short range order in arrangement of atoms or molecules is present. Crystallinity map shows the regions where long range order in arrangement of atoms and molecules is present.

[0084] There is a plurality of known detectors used to collect the signal. Some examples follow. A secondary electron (e.g. Everhart-Thornley) detector provides different contrasts depending on relief or changes in height and may be used to identify the edge of each particle region (110). An EDX (Energy Dispersive X-ray) detector provides information on Atomic weight / number (Z) may be used to identify different elements, and the outer edge of each particle region (110) is determined from a contrast between elements of the particle region (110) and support or vacuum. Intensity from HAADF (High Angular Annular Dark Field) or direct detection detector can give information on whether part of the sample is transmittable. A backscattered electron detector provides different contrast depending on atomic weight and crystal orientation and may be used to identify the edge of each particle region (110).. The signal may be collected from above the sample {e.g. for backscattered electrons, secondary electrons (electrons originating from inelastic scattering of the primary electrons within the sample), Auger electrons, X-rays, photons), and / or below the sample {e.g. scattered / diffracted electrons, unscattered electrons, X-rays, photons), and / or at / from the sample e.g. current).

[0085] The 2D intensity map (200) may, for example, be obtained from the electrons that are emitted (secondary electrons or Auger electrons) as a result of interaction of the electron beam and the sample, collected above the sample, containing information of the surface morphology of the sample.

[0086] The 2D intensity map (200) may, for example, be obtained from the electrons that are backscattered (backscattered electrons) as a result of interaction of the electron beam and the sample, collected above the sample, containing information of the atomic number (Z) distribution or crystal orientation variation in the sample.

[0087] The 2D intensity map (200) may, for example, be obtained from the photons / X-rays that are emitted as a result of interaction of the electron beam and the sample, collected above and / or below the sample, containing information on the sample composition.

[0088] The 2D intensity map (200) may, for example, be obtained from unscattered electrons passing through the sample substrate, holes in the substrate, and the sample, collected below the sample.

[0089] The 2D intensity map (200) may, for example, be obtained from scattered / diffracted electrons passing through the sample substrate, holes in the substrate, and the sample, collected below the sample.

[0090] The region 2D intensity map (210) is a contiguous subregion of the 2D intensity map (200) and corresponds to at least a portion, preferably a whole of the particle region (110) against a background (220).

[0091] A portion of a particle region (110) typically arises when a part of the particle is out of frame. The 2D intensity map (200) contains at least one region 2D intensity map (210). The 2D intensity map (200) may contain multiple region 2D intensity maps (210). The multiple region 2D intensity maps (210) correspond to multiple different particle regions (110) (and / or portions thereof) in the sample (100). In other words, each region 2D intensity map (210) of the multiple corresponds to at least a portion, preferably a whole of the corresponding particle region (110) against a background (220).

[0092] EM may be any device emitting a charged particle beam capable of producing both the two-dimensional, 2D, intensity map (image) and the ED data of a sample. An example of an EM is a scanning electron microscope (SEM), or scanning transmission electron microscope (STEM). Examples of EM providers include Zeiss, Tescan, JEOL, Hitachi, ThermoFisher. Standard methods for acquisition of a 2D intensity map and the ED data of a sample are known in the art, for instance, using standard protocols of the EM, and / or from text book teachings such as Williams D.B. and Carter C.B. “Transmission Electron Microscopy”, Springer New York NY, 2009.

[0093] Typically an EM comprises:

[0094] - a source of charged particles (electrons);

[0095] - a focusing unit configured for forming the charged particles into an EM beam;

[0096] - a deflector unit configured for adjusting the location of the EM beam on the sample or sample region;

[0097] - one or more detectors configured for detecting particles resulting from interaction of the EM beam with the sample or sample region. The detector(s) is positioned above the sample (for collecting the 2D intensity map) and / or after the sample (for collecting the 2D intensity map and / or ED data);

[0098] - a controller configured for controlling the EM;

[0099] - a memory configured for storing computer readable instructions for instructing the controller to operate the EM according to the present disclosure.

[0100] - a sample stage for adjusting the location of the sample or sample region with respect to the beam

[0101] - a vacuum chamber and attached vacuum pumps and vacuum sensors

[0102] The beam dose, related to a quantity of electrons received by the sample per point visited by the EM beam. It is typically adjustable in an EM. The beam dose may be adjusted by adjusting: i) a dwell time, which is a quantity of time spent by the EM beam at the visited location of the sample (before the EM beam is moved to a subsequent location), and / or ii) the beam kinetic energy, which is related to a strength of the EM beam. A higher beam kinetic energy penetrates to a greater depth compared to a lower beam kinetic energy. The beam kinetic energy is adjusted by changing an acceleration current and / or acceleration voltage of the EM accelerator. Depending on the instrument acceleration voltage may range between 1 to 300 keV. Depending on the instrument an acceleration current may range between 100 fA to 1 pA. iii) Beam footprint size or size of the beam footprint at the point where the EM beam contacts the sample. Depending on the instrument, probe size may be between 6 A and 1 pm in diameter.

[0103] In a typical EM, useful dose ranges between 1 electron / point to 1 x 109electrons / visited point with 1 x 106electrons / visited point being typically used for collection of ED data. In a typical EM, useful dose ranges from 0.01 electron per angstrom2per second to 8 x 106electrons per angstrom2per second.

[0104] The target location dose is the EM beam dose at a point that is the beam target location (420 a to d). The target location dose may be influenced by the number of times the EM beam visits the beam target location (420 a to d) during the data collection session.

[0105] The region dose is sum of the individual target location doses received by a particle region (110) during a data collection session.

[0106] The 2D intensity map is typically produced, for instance, by scanning the EM beam across the sample (100). Types of scanning pattern include Raster scanning, snake-pattern scanning, random position scanning. By raster scan, it is meant that the EM beam is controlled to move across the sample in an array of parallel sweeps.

[0107] The signal arsing from an interaction with the EM beam may be collected by one or more detectors positioned above the sample (e.g. for backscattered electrons, secondary electrons, Auger electrons, X-rays, photons), and / or one or more detectors positioned below the sample (e.g. scattered / diffracted electrons, unscattered electrons, X-rays, photons), and / or one or more by measurement of current at / from the sample. A known common technique for measurement of current is electron-beam induced current (EBIC). It is based on creation of electron-hole pairs in the semiconductor sample by the microscope's electron beam (https: / / en.wikipedia.org / wiki / Electron_beam- induced_current).

[0108] The 2D intensity map is typically produced at low beam dose. By low beam dose, it is meant that the beam dose is lower compared to acquisition of ED data. The difference in beam dose may be a factor of at least 1.5, 2, 10, 20 or 30. As an example, a beam dose for generation of a 2D intensity map may be generated using: an EM accelerator voltage of 1 to 300 keV, more preferably 1 to 100 keV and / or a dwell time of 1 ns to 1 ps,

[0109] Typically, the dwell time is shorter (e.g. 1 000 to 10 000 times shorter) for generating a 2D intensity map compared with acquisition of ED data. A meaningful intensity for a 2D intensity map may be obtained from at least 10 electrons received by the sample region per scanned point.

[0110] The region 2D intensity map (210) is generated from the 2D intensity map (200), and is a portion of the 2D intensity map containing the particle region (110).

[0111] A pattern of electrons, ED pattern, results from the EM beam after having interacted with the particle region (110) at the one or more beam target locations (420 a to d) and is detected using a suitable detector, and recorded. The ED data may be represented as an electron diffraction, ED, pattern containing information of detection events at x, y coordinates on the detector and optionally time of arrival.

[0112] In obtaining the ED data at multiple beam target locations, coils of the deflector unit controlling the direction of the EM beam may be set in a scanning pattern, and the EM beam energy is de-activated (zero energy) where the EM beam is not at a beam target location (420 a to d). In other words, coils controlling the direction of the EM beam may be set in a scanning pattern, and the EM beam energy is activated only where the EM beam is at a beam target location (420 a to d). Types of scanning pattern include Raster scanning, Snake-pattern scanning, Random position scanning. By raster scan, it is meant that the EM beam is controlled to move across the sample in an array of parallel sweeps. The ED data is typically produced at high beam dose. By high beam dose, it is meant that the beam dose is higher (for instance, longer exposure time and / or higher beam current at certain beam position) compared with acquisition of 2D intensity map. The difference in dose may be a factor of at least 1 .5, 2, 10, 20 or 30. The beam dose for generation of the ED data depends on the applied current, acceleration voltage, the dwell time and the illumination area.

[0113] The EM accelerator voltage can be varied from 1 to 300 keV, preferably 30 to 300 keV, and / or the dwell time can vary from 1 ns to 1 ps. Typically, the dwell time is longer (e.g. 1 000 to 10 000 times longer) for acquisition of ED data compared with generating a 2D intensity map. A meaningful ED pattern may be obtained from at least 100 to 1 x 106electrons received by the sample region per scanned point. Because the present invention collects ED data from the thinnest parts of the sample, the beam kinetic energy accelerator voltage may be 1 to 30 keV.

[0114] Maximum sample thickness that is possible to transmit with electron beam is determined by the electron beam acceleration voltage and material atomic number. In general, the thicker the sample the higher acceleration voltage that is needed to transmit such region. The sample thickness that can be transmitted may be determined comprising the equation: t = -A * ln(1 - T) where t is thickness;

[0115] A is mean free path of electron in material, and depends on electron beam energy / acceleration voltage and material atomic number;

[0116] T - transmission probability (usually taken as 0.37).

[0117] When EM beam is “activated” it means that the EM beam is of an energy to obtain ED data (typically 1 keV to 300 keV depending on sample thickness).

[0118] As mentioned elsewhere herein, the EM beam is only activated at one or more beam target locations (420 a to d). Parts of the particle region (110) not corresponding to one or more perimeter locations (320 a to d) on the region perimeter (320) do not receive activated EM beam energy. In particular, during the acquiring of ED data from the particle region (110) the EM beam is activated only at the one or more beam target locations (420 a to d).

[0119] In particular, during the method, the EM beam for acquiring (the) ED data is activated only at the one or more beam target locations (420 a to d).

[0120] During the method, the EM beam for acquiring (the) ED data is not activated at any location that is not a beam target location (420 a to d) on the particle region (110) corresponding to one or more locations (320 a to d), perimeter locations.

[0121] During obtaining ED data, the EM beam may be deactivated during repositioning between two spatially separated beam target locations (420 a to d). The EM beam may be sequentially and repeatedly activated and deactivated. For instance, when the beam target locations are not adjacent such as in the pseudo-scan pattern described elsewhere herein, the EM beam is deactivated while the beam moves between different beam target locations. The EM beam is preferably deactivated by blocking / blanking the EM beam by a beam-blanker. As understood in the art, there are two main types of beam-blankers. A magnetic beam-blanker inserts an aperture to physically block the beam. An electrostatic beam-blanker deflects the beam to the side so that it does not interact with the sample. For blanking in between repositioning the beam for electron diffraction, the electrostatic blanker is preferred.

[0122] During obtaining ED data, the EM beam may be continuously activated. For instance, when the perimeter region (310) is a closed loop and the beam target locations are adjacent, the continuously activated beam sweeps around the particle region (110) (e.g. in a clockwise or anti-clockwise direction).

[0123] The region perimeter (310) of a particle region (110) represents the outermost edge of the particle region (110) as determined from the region 2D intensity map (210). The region perimeter (310) may be: a continuous or closed loop (no gaps), or a discontinuous loop (one or more gaps), or a truncated loop (typically caused by the particle region (110) being partially out of frame, thereby causing the region 2D intensity map (210) to correspond to only a portion of the particle region (110)). For instance, the region perimeter (310) of a solid circular particle region (110) will be a closed circular loop or band. In practice, the region perimeter (310) is disposed at an interface between the region 2D intensity map (210) and the background (220), on the side of the region 2D intensity map (210) (and not on the background side of the interface). In other words, the region perimeter (310) is disposed on the outermost edge of the region 2D intensity map (210) where intensity is present compared with the background (e.g. there may be a noticeable (higher than signal-to-noise ratio) intensity value delta (difference) between particle and background).

[0124] The region perimeter (310) may have width that is a fraction of a distance between the outermost edge and a centre of gravity of the region 2D intensity map (210). The width of the region perimeter (310) may be constant along a path of the region perimeter (310). According to one aspect, the region perimeter (310) may have width related to an beam footprint size of the beam. The width may be equal to or greater than the beam footprint size. An increasing beam footprint size may be reflected by an increasing region perimeter (310) width. As a general guidance, a width may be 1 to 10 pixels, preferably 3 to 5 pixels.

[0125] According to one aspect, the region perimeter (310) may have a width related to pixel step size. Pixel step size is a separation distance between two electron beam positions on the sample (100). The width may be equal to or greater than the pixel step size. An increasing pixel step size may be reflected by an increasing region perimeter (310) width.

[0126] According to one aspect, the region perimeter (310) may have width related to the beam footprint and pixel step size. An increasing (beam footprint + pixel step size) may be reflected by an increasing region perimeter (310) width.

[0127] The region perimeter (310) may be represented as a set of co-ordinates and intensities or as an image in which the region perimeter (310) has an intensity against a blank (uniform) background. For example, the region perimeter (310) may be represented in a 2D region perimeter map (300), containing a spatial (x-y) indication of regions where the region perimeter (310) is present er absent. The 2D region perimeter map (300) is typically a pixel array, and visualized as an image.

[0128] According to one aspect:

[0129] - the region perimeter (310) is represented in a 2D region perimeter map (300) by a first indicator (e.g. value 1) disposed at positions of the map (300) corresponding to the particle perimeter (310), and - all other regions of 2D particle perimeter map (300) are represented by a second indicator different from the first indicator (e.g. value 0)

[0130] - during the acquiring of electron diffraction, ED, data ( / .e. an ED pattern) from the particle region (110c), the beam of the electron microscope is activated only at one or more beam target locations (420 a to d) of the particle region (110c) corresponding to one or more perimeter locations (320 a to d) of the first indicator in the region perimeter map (300).

[0131] One or more perimeter locations (320 a to d) on the region perimeter (320) are selected which correspond to one or more beam target locations (420 a to d) of the particle region (110). A perimeter location is a location having a centre only within region perimeter (310), and corresponds to the same location of the particle region (110) that is a beam target location (420 a to d) for exposure to the beam.

[0132] Where there is a plurality of perimeter locations (320 a to d), some perimeter locations (320 a to d) or each and every perimeter location (320 a to d) may be discrete, meaning that closest neighbour perimeter locations (320 a to d) are mutually spatially separated in a shortest route along the region perimeter (310) between closest neighbour perimeter locations (320 a to d) on the 2D intensity map (200). Discrete perimeter locations may be separated from the closest neighbour perimeter location (320 a to d) by at least 1 , preferably at least 5 pixels on the 2D intensity map (200).

[0133] The plurality of discrete perimeter locations (320 a to d) may be randomly selected, or selected according to a rule. Examples of rules include: even spacing of multiple perimeter locations (320 a to d) around the region perimeter (310), perimeter locations (320 a to d) located at the thinnest locations of the region perimeter (310). perimeter locations (320 a to d) located in a segment of the region perimeter (310). pattern spacing of multiple perimeter locations (320 a to d) around the region perimeter (310) other than even spacing.

[0134] Where there is a plurality of perimeter locations (320 a to d), some perimeter locations (320 a to d) or each and every perimeter location (320 a to d) may form a continuous path along and within the region perimeter (310). The perimeter locations (320 a to d) are adjacent to (not separated from) the closest neighbour perimeter location (320 a to d). A beam target location (420 a to d) is a location or point on the particle region (110) where the EM beam is activated in order to acquire a diffraction pattern. The EM beam at the beam target location (420 a to d) is static while the beam dose is delivered to the beam target location (420 a to d).

[0135] Examples of beam target locations (420 a to d) are shown in FIGs. 4 and 8, where the particle region is represented by the region 2D intensity map (210). Each beam target location (420 a to d) is determined from the corresponding perimeter location (320 a to d). The region perimeter (310) maps onto the perimeter of the particle region (310), and a perimeter location (e.g. 320 a) selected on the region perimeter (310) can be used to determine a direction and activation of the EM beam, such that the EM beam is activated at a location (beam target location (e.g. 420 a)) on the particle region corresponding to the perimeter location (e.g. 320 a).

[0136] The beam target locations (420 a to d) may be visited by the EM beam in a set sequence or in a random sequence.

[0137] Examples of set sequences include: movement progressing from a first beam target location (420 a to d) to a second beam target location (420 a to d) closest to the first beam location, a third beam target location (420 a to d) closest to the second beam location and so on, in a start to finish direction. For example, where the perimeter region is a closed loop, the EM beam may visit every beam target location (420 a to d) in order in a clockwise or anti-clockwise direction around the loop. In other words, the beam sweeps around the particle region (110) along a route corresponding to the region perimeter (310). movement progressing from beam target location (420 a to d) to beam target location (420 a to d) all disposed on the same row (first row), then from beam target location (420 a to d) to beam target location (420 a to d) all disposed on the same row adjacent to the first row (second row), and so on. This might be implemented in a pseudo-scanning pattern (e.g. Raster scanning, snake-pattern scanning, random position scanning), similar to a conventional scanning pattern wherein the EM is activated only at the locations (420 a to d) on the particle region (110) corresponding to the region perimeter (310). During obtaining ED data, the EM beam may be moved in a set sequence that is a scan pattern, such as a raster scan, snake-pattern scanning, or random position scanning, and the EM beam is deactivated during repositioning between two spatially separated beam target locations (420 a to d).

[0138] During obtaining ED data, the EM beam may be moved in a set sequence that is a path corresponding to region perimeter (310), and the EM beam is continuously activated during repositioning between beam target locations (420 a to d). The beam target locations (420 a to d) are preferably adjacent.

[0139] Each and every beam target location (420 a to d) may be different and visited only once by the EM beam.

[0140] Each and every perimeter location (320 a to d) may be different, and some or all visited at least twice by the EM beam. For example, where the perimeter region is a closed loop, the EM beam may visit every beam target location (420 a to d) in order in a clockwise or anticlockwise direction around the loop several times. Multiple visitations at a lower dose per visited point result in a reduction in beam damage and drift compared with only one beam visitation per point and higher dose per visited point.

[0141] The region perimeter (310) is most preferably determined by image processing of the 2D intensity map (200) or part thereof in order to detect an edge of the region 2D intensity map (210). The inventors have found that the edge detected by image processing yields a region perimeter (310) corresponding to a thin or thinnest part of the particle region (110) from which ED data can be reliably acquired at lower doses than conventionally used.

[0142] Protocols for edge detection are known in the art, for instance from https: / / en.wikipedia.org / wiki / Edge_detection or https: / / en.wiki pedia.org / wi ki / Watershed_(image_processing).

[0143] Examples of standard edge detection algorithms include:

[0144] Canny edge detection (e.g. Canny, J., A Computational Approach To Edge Detection, IEEE Transactions on Pattern Analysis and Machine Intelligence, 8(6):679-698, 1986). Canny edge detection as understood in the art is a multi-step process that involves smoothing the image with a Gaussian filter, finding intensity gradients, applying non-maximum suppression, and using double thresholding followed by edge tracking by hysteresis.

[0145] Sobel operator (e.g. htps: / / en.wikipedia.org / wiki / Sobel operator) and its derivatives; The Sobel operator may be used to find the gradient of the image intensity at each point, thus highlighting regions of high spatial frequency that often correspond to edges. Typically, it uses two 3x3 convolution kernels, one estimating the gradient in the x-direction (horizontal) and the other estimating the gradient in the y-direction (vertical). The gradients can be combined to find the absolute magnitude of the gradient at each point and the orientation. The edge is identified as the pixels with the maximum magnitude.

[0146] Scharr operator (e.g. htps: / / en.wikipedia.org / wiki / Sobel operator) and its derivatives; The Scharr operator as understood in the art is a slight modification of the Sobel operator, designed to give improved rotational symmetry. Like Sobel, Scharr uses convolution kernels to calculate the gradient of the image intensity at each point. The coefficients in the Scharr kernels are typically optimized by the operator to give a better approximation of the image gradient and are therefore considered to give more accurate results for edge orientation than the Sobel operator, especially for high-frequency detail in images.

[0147] Laplace operator (e.g. https: / / en.wikipedia.org / wiki / Laplace_operator) and its derivatives. The Laplace operator as understood in the art is a second-order derivative method used to find areas of rapid change (edges) in images. It is implemented as a convolution with a specific kernel that takes the second derivative in both the x and y directions. Since it is a second-order derivative, the Laplacian operator is sensitive to noise. Typically, the image is smoothed before applying the Laplacian filter to reduce sensitivity to noise.

[0148] Border following (contour detection) algorithm is preferably used to systematically trace an outline of corresponding to the party region within a binary image. After the edge detection step binary map is produced which may be converted to the list of xy coordinates of pixels to be visited with an electron beam. The steps of the border following algorithm include: o Starting at a certain point on the edge of an object. This starting point is often the first white pixel (edge pixel) encountered when scanning the image from top to bottom and left to right. o Once an edge pixel is found, the border following algorithm begins to trace the contour by examining the neighbouring pixels around the current pixel to determine which neighbouring pixel is also part of the edge. o The algorithm follows these rules to move from one edge pixel to the next, effectively "walking" along the border of the object. The rules are followed until a return to the starting pixel, having traced the entire contour. During the tracing, the algorithm keeps a list of the XY coordinates of the visited edge pixels, thereby creating a representation of the object's border.

[0149] Advantageously, edge detection reliably provides a perimeter of the particle region because the particle region is provided on a flat support substrate giving a uniform background for the region 2D intensity map. As particle extends from the support substrate, there is an increase in intensity and greater contrast with the support substrate, which facilitates reliable edge detection.

[0150] It is also appreciated that edges may be detected using a predictive model trained using a training dataset containing multiple instances of a region 2D intensity map tagged with its edge. Examples of suitable predictive models include DeepNets, N4-Fields, DeepEdge, CSCNN, DeepContour, HED. Examples of edge detection using neural networks include:

[0151] - htps: / / www.ncbi.nlm.nih.gov / pmc / articles / PMC7295132 /

[0152] - htps: / / github.com / i008 / deepedge

[0153] - htps: / / www.researchgate.net / publication / 308820325 DeepContour A Deep Co nvolutional Feature Learned by Positive-sharing Loss for Contour Detection https: / / cv-tricks.com / opencv-dnn / edge-detection-hed /

[0154] Prior to edge detection, a noise reduction protocol may be applied to the 2D intensity map (200) or part thereof for reduction or removal or noise. Protocols for noise reduction are known in the art, for instance from htps: / / en.wikipedia.org / wiki / Noise reduction#ln images. Examples of standard noise reduction algorithms include: Gaussian blur, Local Mean filter, Local Median Filter,

[0155] Convolution filter, Low-pass and High-pass filters.

[0156] It is also appreciated that noise may be reduced using a predictive model trained using a training dataset containing multiple instances of a native region 2D intensity map tagged with its corresponding noise-reduced region 2D intensity map. Examples of suitable predictive models include convoluted neural network (CNN), as described, for instance, in EP 3736769 A1 , WO 2023 / 111772 A1.

[0157] The noise reduced 2D intensity map (200) may be intensity rescaled to increase contrast between background (support) and sample region(s). Thresholding may be applied prior to edge detection to create a 2-level (0 and 1 values only) image. A general guidance, the following criteria may be applied: 0 if intensity value is < 0.1*max intensity, and 1 if intensity value was >0.1*max intensity.

[0158] After edge detection, the detected edges may be converted to a mask map, in which the detected edges are represented as a loop shape (continuous, closed, discontinuous, truncated), in particular wherein the loop shape is represented on a mask map by a first indicator (e.g. value 255, white) and a background of the loop shape is represented by on the mask map by a second indicator different from the first indicator (e.g. value 0, black). The loop shape corresponds to the region perimeter (310).

[0159] The width of the loop shape may be adjusted (e.g. made wider towards the inside of the loop or particle region, or made wider towards the inside and / or of the loop or particle region compensate for beam positioning error), which is equivalent to adjusting the width of the region perimeter (310). The width of the loop shape may be increased using a dilate operator, limited to increase width only towards a centre of gravity (or inward) of the particle region. Various methods may be employed to determine an inwards-direction dilation. For instance, a standard dilation may be performed on the detected-edge perimeter, which is masked using a particle silhouette, resulting in a perimeter region that only dilated in a region occupied by the particle and not outside of it. The particle silhouette may be generated by known methods such as described at:

[0160] - http: / / scipy-lectures.org / packages / scikit-imaqe / auto examples / plot labels.html, and https: / / www.mathworks.com / help / images / label-and-measure-objects-in-a-binary- image.html

[0161] The masking may be achieved by applying a logical AND operation between the silhouette and standard-dilated perimeter.

[0162] As an example, a width may be 1 to 10 pixels, preferably 3 to 5 pixels. The final result is the region perimeter (310).

[0163] One or more locations (320 a to d) on the region perimeter (310) are selected which correspond to one or more beam target locations (420 a to d) of the particle region (110).

[0164] The present method may be applied to a 2D intensity map (20) having one region 2D intensity map (210), or having multiple region 2D intensity maps (210).

[0165] The 2D intensity map (200) may contain a single (one) region 2D intensity map (210). In such case, the ED data may contain at least one ED pattern corresponding to the single (one) region 2D intensity map (210).

[0166] According to one aspect the 2D intensity map (200) contains a single (one) region 2D intensity map (210) and the ED data contains: only one ED pattern for the particle region (110) corresponding to the single region 2D intensity map (210). The single (only one) ED pattern may result from o a single (one) beam target location (420 a to d) on the region perimeter (310) determined from the single region 2D intensity map (210);

[0167] According to another one aspect the 2D intensity map (200) contains a single (one) region 2D intensity map (210) and ED data contains: at least two ED patterns for the particle region (110) corresponding to the single region 2D intensity map (210), each ED pattern of the particle region (110) corresponds to a different beam target location (420 a to d) on the region perimeter (310) determined from the single region 2D intensity map (210).

[0168] The present method may be applied to a 2D intensity map (20) having multiple region 2D intensity maps (210). In such case, the methods described herein may applied per region 2D intensity map (210) of the multiple.

[0169] The 2D intensity map (200) may contain a set (Smap) of multiple region 2D intensity maps (210) corresponding to a set (Sparticie) of multiple particle regions (110) in the sample (100). In such case, the ED data may contain at least one ED pattern for each and every particle region (110) of the set (Sparticie) . According to one aspect the 2D intensity map (200) contains the set (Smap) of multiple region 2D intensity maps (210) corresponding to a set (Sparticie) of multiple particle regions (110) in the sample (100), and the ED data contains only one ED pattern for each and every particle region (110) under investigation of the set (Sparticie) . The single (only one) ED pattern may result from a single (one) beam target location (420 a to d) on the region perimeter (310) determined from the region 2D intensity map (210) of the particle region (110) of the set (Sparticie) under investigation;

[0170] According to another aspect the 2D intensity map (200) contains the set (Smap) of multiple region 2D intensity maps (210) corresponding to a set (Sparticie) of multiple particle regions (110) in the sample (100), and the ED data contains at least two ED patterns for each and every particle region (110) under investigation of the set (Sparticie) ; each ED pattern of the particle region (110) under investigation being acquired at a different beam target location (420 a to d) on the region perimeter (310) determined from the region 2D intensity map (210) of the particle region (110) under investigation.

[0171] The 2D intensity map (200) (and region 2D intensity map (200)) and ED data are preferably collected during the same data collection session. In a data collection session, the sample remains in same position relative to a sample holder. In other words, the sample is not removed from the holder between acquisition of the 2D intensity map (200) (and region 2D intensity map (200)) and acquisition of the ED data. In other words, the 2D intensity map (200) (and region 2D intensity map (200)) and ED data are not acquired in different data collection sessions.

[0172] The collected ED data may be stored and later processed to reconstruct an image. Methods for processing ED data are known in the art, for instance, using methods from 4- dimentional scanning transmission electron miscoscopy (4D STEM), analytical ptychrography, Real Time Integration Centre of Mass (riCOM) Reconstruction, strain or grain orientation mapping, virtual bright- and dark-field image

[0173] Further provided is a method of controlling an electron microscope, EM, for obtaining electron diffraction, ED, data from a sample (100) containing a particle region (110) (for which ED data is desired) wherein the method comprises:

[0174] - sending instructions to the EM to obtain a two-dimensional intensity map, 2D intensity map (200), from the sample (100), wherein the 2D intensity map (200) contains a region 2D intensity map (210) corresponding to the particle region (110);

[0175] - sending instructions to the EM to acquire electron diffraction, ED, data from the particle region (110), where a beam of the EM is activated only at one or more beam target locations (420 a to d) of the particle region (110) corresponding to one or more locations (320 a to d) only on a region perimeter (310), wherein the region perimeter (310) is determined from the region 2D intensity map (210).

[0176] Further provided is a method for obtaining high-throughput electron diffraction patterns, ED patterns, of each particle region (110) in a (single) sample (100) containing a set (Sparticie) of multiple particle regions (110) using an electron microscope, EM, comprising:

[0177] - sending instructions to the electron microscope, EM, to obtain a two-dimensional intensity map, 2D intensity map (200), from the sample (100), wherein the 2D intensity map (200) contains multiple region 2D intensity maps (210), each region 2D intensity map (210) corresponding to (at least a part, preferably a whole of) a particle region (110) of the set (Sparticie) ;

[0178] - sending instructions to the EM to acquire an ED pattern from each and every particle region (110) of the set (Sparticie) , wherein

[0179] - a beam of the EM is activated only at one or more beam target locations (420 a to d) of each particle region (110) of the set (Sparticie) ,

[0180] - the one or more beam target locations (420 a to d) corresponds to one or more locations (320 a to d) on a region perimeter (310) of each particle region (110) of the Set (Sparticie) ,

[0181] - the region perimeter (310) is determined from the region 2D intensity map (210) of each particle region (110) of the set (Sparticie) .

[0182] Other features described herein may be applied to the method for obtaining high- throughput electron diffraction patterns, ED patterns, of each particle regions (110) in a (single) sample (100) containing a set (Sparticie) of multiple particle regions (110) using an electron microscope, EM.

[0183] Further provided herein is a method for obtaining electron diffraction, ED, data from a sample (100) containing a particle region (110) (for which ED data is desired) while reducing beam damage to the particle region (110) during using one or more of the methods described herein. Further provided herein is a method for obtaining tomographic electron diffraction, ED, data from a sample (100) containing a particle region (110) (for which ED data is desired) comprising collecting a set of multiple ED data acquisitions using the methods described herein, wherein each ED data acquisition is performed at a different rotational (tilt) angle of the sample (100).

[0184] Further provided herein is a method for obtaining tomographic electron diffraction, ED, data from a particle region (110) of a sample (100) comprising collecting a set of multiple ED data acquisitions using the methods described herein, wherein each ED data acquisition is performed at a different rotational (tilt) angle of the particle region (110). The rotation is typically around a single rotational axis of the particle region (110), in particular of the support (110).

[0185] Provided herein is an EM (and computer processor), configured to carry out the method described herein. The EM may be capable of providing a EM beam having a potential of 1 keV to 300 keV. Since the present disclosures allow ED data to be collected using a lower beam energy, the EM may be capable of providing a EM beam having a potential of 1 keV to 30 keV.

[0186] Provided herein is a electron microscope, EM, having an EM beam and a processor adapted to execute the steps of the method as described herein.

[0187] The method described herein is a computer-implemented method. It may be performed at least partly or fully by a computer.

[0188] Provided herein is a computer implemented method for obtaining electron diffraction, ED, data from a sample (100) using an electron microscope, EM, having an EM beam, the sample (100) containing a particle region (110) comprising one particle (112) or a cluster of multiple particles (112), the method comprising steps:

[0189] - outputting instructions for the EM for acquiring a two-dimensional intensity map, 2D intensity map (200), from the sample (100), wherein the 2D intensity map (200) contains a region 2D intensity map (210) corresponding to the particle region (110);

[0190] - receiving the two-dimensional intensity map, 2D intensity map (200) from the EM;

[0191] - determining from the region 2D intensity map (210), a region perimeter (310); - determining from the region 2D intensity map (210) one or more beam target locations (420 a to d) corresponding to one or more locations (320 a to d), perimeter locations, only on the region perimeter (310),

[0192] - outputting instructions for the EM for acquiring the ED data from the particle region (110). The instructions for acquiring (the) ED data indicate activation of the EM beam only at the one or more beam target locations (420 a to d). In particular, during the method, instructions for acquiring (the) ED data indicate activation of the EM beam only at the one or more beam target locations (420 a to d). In particular, during the method, the EM beam for acquiring (the) ED data is instructed to be activated only at the one or more beam target locations (420 a to d)).

[0193] Further provided is a computing device or system or processor configured for performing a method as described herein, or a part thereof. The image processing and edge detection may be performed using a computing device or system or processor.

[0194] Further provided is a computer program or computer program product having instructions which when executed by a computing device or system cause the computing device or system or processor to perform a method as described herein, or a part thereof.

[0195] Further provided is a computer readable medium having stored thereon a computer program (product) having instructions which when executed by a computing device or system or processor cause the computing device or system to perform (each of the steps of) the method as described herein, or a part thereof.

[0196] Further provided is a data stream which is representative of a computer program or computer program product having instructions which when executed by a computing device or system or processor cause the computing device or system to perform (each of the steps of) the method as described herein, or a part thereof.

[0197] The method may be performed using a standard computer system or processor such as an Intel Architecture IA-32 based computer system 2, and implemented as programming instructions of one or more software modules stored on non-volatile (e.g. hard disk or solid- state drive) storage associated with the corresponding computer system. However, it will be apparent that at least some of the steps of any of the described processes could alternatively be implemented, either in part or in its entirety, as one or more dedicated hardware components, such as gate configuration data for one or more field programmable gate arrays (FPGAs), or as application-specific integrated circuits (ASICs), for example. Example

[0198] A sample was prepared containing particles of Lithium iron phosphate (LiFePCL) disposed on a support substrate of amorphous continuous ultrathin (2-5 nm thick) carbon film. The sample was loaded into a Tescan Mira FEG SEM with modified sample stage and external scan engine. Microscope was additionally outfitted with Advacam AdvaPix direct electron detector for collection of ED data and custom-built ADF detector (htps: / / doi.Org / 10.1016 / j.ohx.2023.e00413) for STEM image (2D intensity map) collection. Using EM parameters: acceleration voltage 30 keV, beam current 100 pA, 1 microsecond dwell time, a 2D intensity map (220) of a part of the sample was obtained by high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), as shown in FIG. 5, wherein a particle (210) and the background (220) are indicated. A region perimeter (310) was generated from the 2D intensity map (220) as shown in FIG. 6 using image edge detection as described herein. In brief, the 2D intensity map (220) was denoised. The denoised image was intensity rescaled to increase contrast between background and sample regions. The image was thresholded 10% of maximum 2D map intensity to create 2-level (0 and 1 values only) image. 0 was assigned if intensity value was < 0.1*max intensity, and assigned 1 if value was >0.1*max intensity. Canny detection was performed on the thresholded image. Dilate operator was applied with kernel size of 4 to increase the width of perimeter to compensate for beam positioning error, then a particle silhouette was created, and afterwards a logical AND operation performed using the silhouette and dilated perimeter, resulting in a dilated perimeter that is within particle boundaries and not outside of it. Three perimeter locations (320v, 320w, 320x) were selected at different discrete locations of the region perimeter (310) as shown in FIG. 7. Using EM parameters acceleration voltage 30 keV, beam current 100 pA, dwell time 10 millisecond, ED data was collected at three target locations (420v, 420w, 420x) of the sample corresponding to the three perimeter locations (320v, 320w, 320x) as shown in FIG. 8 wherein the sample is represented by its 2D intensity map (220). As controls, ED data was collected at two non-target locations (422a, 420b) using the same EM parameters. The results are shown in FIGs. 9A to 9E, each depicting the ED data - an ED pattern - acquired from each of target locations 420v, 420w, 420z, 422a, 422b of FIG. 8. In FIG. 9A (target location 420v), FIG. 9B (target location 420w), FIG. 9C (target location 420x), each acquired ED pattern shows a pattern of electron diffraction spots, from the particle region. By contrast FIG. 9D (target location 422a) and FIG. 9E (target location 422b) contain no detectable ED pattern. The ED data collected at target locations 420v, 420w, 420z used a low beam dose, causing minimal damage to the particle region. The ED data collected at non-target locations 422a, 422b such as acquired in a raster scan would need a higher beam dose to obtain useful ED data thereby causing sample damage, and the damage would extend across the whole of the sample because the beam would typically remain turned on during the whole of the raster-scan.

Claims

Claims1. A method for obtaining electron diffraction, ED, data from a sample (100) using an electron microscope, EM, having an EM beam, the sample (100) containing a particle region (110) comprising one particle (112) or a cluster of multiple particles (112), the method comprising steps:- receiving a two-dimensional intensity map, 2D intensity map (200), from the sample (100) using the EM, wherein the 2D intensity map (200) contains a region 2D intensity map (210) corresponding to the particle region (110);- determining, from the region 2D intensity map (210), a region perimeter (310);- determining from the region 2D intensity map (210) one or more beam target locations (420 a to d) corresponding to one or more locations (320 a to d), perimeter locations, only on the region perimeter (310),- acquiring electron diffraction, ED, data from the particle region (110), using the EM; wherein during the acquiring of ED data from the particle region (110) the EM beam is activated only at the one or more beam target locations (420 a to d).

2. The method according to claim 1 , wherein:- the region perimeter (310) is represented in a 2D region perimeter map (300) by a first indicator disposed at locations of the map (300) corresponding to the region perimeter (310);- all other regions of 2D region perimeter map (300) are represented by a second indicator different from the first indicator; and- during the acquiring of ED data from the particle region (110c), the EM beam is activated only at one or more beam target locations (420 a to d) of the particle region (110c) corresponding to one or more perimeter locations (320 a to d) having the first indicator in the 2D region perimeter map (300).

3. The method according to claim 1 or 2, wherein the region perimeter (310) is determined from the region 2D intensity map (210) using image processing and edge detection, wherein the region perimeter (310) is determined from the detected edge.

4. The method according to any one of claims 1 to 3, wherein a quantity of perimeter locations (320 a to d) is greater than 1 , and perimeter locations (320 a to d) are randomly selected, or selected according to a rule.

5. The method according any one of claims 1 to 4, wherein:- the activated beam has a beam dose at the beam target location (420 a to d) of 0.01 electron per angstrom2per second to 8 x 106electron per angstrom2per second.

6. The method according to any one of claims 1 to 5, wherein during obtaining ED data, the EM beam is deactivated during repositioning between two spatially distinct beam target locations (420 a to d).

7. The method according to any one of claims 1 to 6, wherein during obtaining ED data, the EM beam is continuously activated during repositioning between two adjacently- located beam target locations (420 a to d).

8. The method according to any one of claims 1 to 7, wherein during the obtaining ED data, the EM beam is moved in a scan pattern, such as a raster scan, snake-pattern scanning, or random position scanning, and the EM beam is deactivated during repositioning between two spatially separated beam target locations (420 a to d).

9. The method according to any one of claims 1 to 7, wherein during the obtaining ED data, the EM beam is moved in a path corresponding to the region perimeter (310), and the EM beam is continuously activated during repositioning between beam target locations (420 a to d).

10. The method according to any one of claims 1 to 9, wherein at least some or all of the beam target locations (420 a to d) is visited:- only once by the EM beam during a data collection session, or- at least twice by the EM beam during a data collection session.

11. A method of controlling an electron microscope, EM, to carry out a method according to any one of claims 1 to 10.

12. A computing device or system configured for performing the method according to claim11.

13. A computer program or computer program product having instructions which when executed by a computing device or system cause the computing device or system to perform the (control) method according to claim 11 .

14. A computer readable medium having stored thereon a computer program (product) having instructions which when executed by a computing device or system cause the computing device or system to perform the (control) method according to claim 11 .

15. An electron microscope, EM, having an EM beam and a processor adapted to execute the steps of the method of any of claims 1 to 10.

16. A computer implemented method for obtaining electron diffraction, ED, data from a sample (100) using an electron microscope, EM, having an EM beam, the sample (100) containing a particle region (110) comprising one particle (112) or a cluster of multiple particles (112), the method comprising steps:- outputting instructions for the EM for acquiring a two-dimensional intensity map, 2D intensity map (200), from the sample (100), wherein the 2D intensity map (200) contains a region 2D intensity map (210) corresponding to the particle region (110);- receiving the two-dimensional intensity map, 2D intensity map (200) from the EM;- determining from the region 2D intensity map (210), a region perimeter (310);- determining from the region 2D intensity map (210) one or more beam target locations (420 a to d) corresponding to one or more locations (320 a to d), perimeter locations, only on the region perimeter (310),- outputting instructions for the EM for acquiring the ED data from the particle region (110), wherein the instructions for acquiring (the) ED data indicate activation of the EM beam only at the one or more beam target locations (420 a to d).

17. A computing device or system configured for performing the method according to claim 16.

18. A computer program or computer program product having instructions which when executed by a computing device or system cause the computing device or system to perform the method according to claim 16.

19. A computer readable medium having stored thereon a computer program (product) having instructions which when executed by a computing device or system cause the computing device or system to perform the method according to claim 16.

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