Compositional mapping employing variable charged particle beam parameters for imaging and energy-dispersive x-ray spectroscopy

Abstract

To provide a method of mapping compositional variation within a specimen.SOLUTION: A method comprises: acquiring an electron backscatter image of the surface of the specimen using a first set of electron beam parameters; identifying, from the electron backscatter image, a plurality of locations of areas or points on the specimen to be analyzed by energy dispersive X-ray spectroscopy (EDS); acquiring an EDS spectrum from each of the identified locations or points using a second set of electron beam parameters that are different than the first set of electron beam parameters; and generating a map of compositional variation across the specimen from the plurality of EDS spectra.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] This application relates to charged particle beam microscopes and charged particle beam microscopy methods. In particular, this application relates to systems and methods for imaging and compositional mapping of specimens using variable beam parameters of an incident charged particle beam.

[0002] (Incorporation by reference) All patents, patent application publications, and other publications mentioned in this specification are hereby incorporated by reference in their entirety as if fully set forth herein.

Background Art

[0003] In many biochemical and chemical analysis techniques, it is necessary to obtain spatially resolved data regarding the area or volume distribution of various structures, molecules, and / or elements within one or more samples. To collect such data, chemical analyzers can be closely combined with imaging devices. For example, in medicine, the distribution of special coloring tags or fluorescent tags within tissue samples can be used to identify specific proteins, diseased tissue, gene expression regions, cell structures, and the like. In such studies of distributions, optical detectors such as cameras may be used that interface with an optical microscope or an electron microscope. In the semiconductor industry, an electron microscope may be used to collect the distribution of impurities or structural inhomogeneities within a wafer or a device-supporting layer. In the mining industry, when examining a sample under an electron microscope, the distribution of minerals, or the distribution of elements within various minerals, may be examined by detecting characteristic X-rays emitted from the surface of a rock sample. In some cases, the specimen may be a particulate sample composed of a number of separate particles of sand or silt that are not attached to each other. Generally, the specimen to be analyzed can be any flat surface of any material. For example, in some other examples, the specimen may include a layer of a semiconductor device or a polished plane of a rock sample. In many cases, either the separate particles or the rock sample can be embedded in an embedding agent such as epoxy.

[0004] Often, samples prepared for microscopic analysis are much larger than the field of view of the microscope used to image the sample. Thus, an important first step for data acquisition is to accurately understand the overall structure of the sample to be investigated, which includes finding and locating the various regions or structures of interest relative to the sample coordinates and recording those coordinates for future research and visualization after data acquisition. In addition to this first step, a software product known as Thermo Scientific™ Maps™ software is available from Thermo Fisher Scientific (Waltham, Massachusetts, USA) to facilitate subsequent data collection and data analysis steps. During data collection, the Maps™ software can automate the acquisition of a series of tile images to create a complete overall image of the sample. The Maps™ software can also automatically stitch together the acquired images to form a single overall image. After acquisition, the individual images and tile sets can also be overlaid on each other and configured into an editable multi-layer structure. For individual layers, selective hiding, showing, transparent overlay, and alignment with other images or layers are possible. The user can freely zoom and pan to examine the acquired data and add annotations. The area encompassed by the tile set can be the same size as the movement range of the sample stage. This software can be used to acquire and analyze data from any type of microscope, such as an optical microscope, a scanning electron microscope, a transmission electron microscope, a focused ion beam microscope, etc. Finally, this software can also combine and compare images of a single specimen obtained from different detectors or systems, for example, images of the specimen obtained from both backscattered electrons and secondary electron emission imaging or X-ray induced emission.

[0005] X-ray spectroscopy (Energy-dispersive X-ray spectroscopy, EDS, EDX, EDXS, or XEDS) is an analytical technique particularly useful for elemental mapping of samples within an electron microscope. In such an analysis, while applying an electron beam to the sample by the electron microscope column of a scanning electron microscope (SEM), a transmission electron microscope ( TEM), or a scanning transmission electron microscope ( STEM), the emission of characteristic X-rays from the specimen is detected. Under excitation by the electron beam, each of a plurality of elements within the sample emits a corresponding characteristic X-ray emission spectrum. The X-ray spectral signals from such each element may be separated from each other and recorded according to the position on the specimen (for example, as a set of images such as the above-mentioned tiled and / or stratified images).

[0006] One useful function of the Maps (trademark) software is that it can automatically perform a second instance of data collection across the surface of a specimen based on the analysis of the results of a first instance of data collection that precedes it. This function is useful for compositional mapping in that, during such mapping, it is possible to perform an analysis of the image data after a first episode of image data collection, and based on that analysis, plan and execute subsequent episodes of compositional data collection. This intervening analysis can include automatically partitioning an image (which may be an overall image constructed from the alignment of multiple acquired images) into individual particles and / or grains by the automatic identification of particle boundaries and / or grain boundaries. After the partitioning of the image, the software can control the specimen stage and / or the scanable incident beam to examine selected points within each identified specimen particle or grain. As an example, the first imaging may be performed by detecting backscattered electrons emitted from a sample within an electron microscope by a first detector, and subsequently, the compositional data collection may be performed by energy-dispersive X-ray spectroscopy using a second detector within the same microscope.

[0007] Unfortunately, currently available compositional mapping algorithms related to electron microscope-based EDS analysis do not accommodate changes in electron beam voltage during data acquisition. As a result, the same electron beam settings (e.g., beam energy controlled by beam acceleration voltage) must be shared throughout a data collection session that encompasses both detection of backscattered electrons for imaging and detection of emitted X-rays for chemical analysis. To obtain sufficient X-ray signal intensity at each sampling position on the specimen, a commonly high beam acceleration voltage must be utilized. However, the inventors have found that such conditions may not be optimal for imaging backscattered electrons from granular samples. This problem occurs because using a high beam voltage often results in a large “depth of field” for electron penetration into the sample, which in turn causes the resulting image to often appear as a “defocused” and blurred image at grain boundaries. This blurriness is an artifact of the larger electron interaction volume at high beam voltages, which causes surface features to be blurred by subsurface features.

[0008] FIG. 1 is a flow diagram of a known algorithm workflow for generating a compositional map of a specimen. In step 101, the first step, a backscattered electron (BSE) image of the specimen is acquired. The image may include only a single image frame (i.e., without movement of the stage holding the specimen during image acquisition), or may be a composite image generated by aligning, then overlaying and / or merging a plurality of image frames. If there is a background signal due to the specimen encapsulant (e.g., epoxy), in step 103, the next step, it is subtracted from the acquired backscattered electron signal that makes up the image. In step 105, the background-corrected image is automatically analyzed to identify spatially separated particles (if any) of the specimen and to determine the boundaries and stage coordinates of such particles. In step 107, the background-corrected image is further automatically analyzed to identify individual crystallites within the specimen and to determine the coordinates of the boundary positions of such crystallites with reference to either a sample-based and / or a laboratory-based reference coordinate system. Finally, in step 109, one or more sampling positions within each of the plurality of identified crystallites are selected, and an EDS compositional analysis at each position is obtained by measuring the energy spectrum of the X-rays emitted from each sampling position when the electron beam is applied to each sampling position.

[0009] Since known algorithm workflows (Figure 1) for generating compositional maps do not accommodate electron beam adjustment, the same electron beam parameters (e.g., beam current and beam energy, the latter being controlled by the beam acceleration voltage) must be used during acquisition of backscattered electron images (step 101) and during EDS compositional analysis (step 109). Unfortunately, the inventors have found that the beam parameters optimal for obtaining an acceptable backscattered electron image are not optimal for obtaining an X-ray spectrum, and vice versa. If the beam parameters are set from the start to values selected to generate an acceptable X-ray spectrum within a reasonable data acquisition time (e.g., a beam current of 5 nA and a beam acceleration voltage of 20 - 30 keV), the grain boundaries in the backscattered electron image become unclear due to the penetration of electrons beneath the surface of the grains. Inadequate imaging leads to uncertainty in selecting the most representative positions for subsequent compositional analysis. As an example, a “reasonable” X-ray spectrum analysis speed corresponds to collecting the entire X-ray spectrum at each analysis surface position (i.e., point) spaced within a Cartesian grid with a lattice spacing of 10 μm from a circular sample with a diameter of 30 mm within 2 hours. This corresponds to a spectrum collection speed of about 110 spectra per second or more. For each such X-ray spectrum to have acceptable signal-to-noise characteristics, each X-ray spectrum needs to correspond to the detection of about 1000 X-ray photons per millisecond. The collection area of the X-ray detector linearly affects the collection speed, and a detector with a collection area of about 100 mm 2 is preferred for this task.

[0010] Figure 2 is a backscattered electron image showing a typical example of problems that occur when the same beam voltage used for X-ray analysis is also used for BSE imaging of the same sample. Specifically, the edges of particles 201 and 202, and the grain boundaries between the grains 202a and 202b of particle 202 are not sufficiently distinct. On the other hand, when the electron beam is adjusted so that the edges of the particles and grains are distinct, extra analysis time is required to obtain a noise-free X-ray spectrum, thereby reducing the overall analysis efficiency. Therefore, in the art, imaging and compositional mapping techniques that maintain both accuracy and efficiency are needed.

SUMMARY OF THE INVENTION

[0011] According to a first aspect of the present disclosure, a method for mapping differences in composition within a specimen includes obtaining an electron microscope image of the surface of the specimen using a first set of electron beam parameters; identifying a plurality of positions or points in regions on the specimen to be analyzed by energy dispersive X-ray spectroscopy (EDS) from the electron backscattered image; obtaining an EDS spectrum from each of the identified positions or points using a second set of electron beam parameters different from the first set of electron beam parameters; and generating a map of differences in composition across the specimen from the plurality of EDS spectra. Generally, the electron microscope image is obtained by backscattered electron (BSE) imaging using a scanning electron microscope (SEM). However, if the specimen includes a thin plate having a thickness of less than about 200 nm, or less than about 100 nm depending on the type of sample (optionally thinned by ion beam milling), the electron microscope image may be obtained by transmission electron microscopy using a transmission electron microscope (TEM).

[0012] According to a second aspect of the present disclosure, an electron microscope system includes: (a) an electron source and an electron optical column; (b) a sample stage within a vacuum chamber for supporting a sample of the specimen; (c) a first detector for detecting electrons backscattered from the specimen upon collision of an electron beam with the specimen; (d) a second detector for detecting X-rays emitted from the specimen upon collision of the electron beam with the specimen; and (e) one or more computer processors including executable instructions that, when executed by the one or more computer processors, cause the one or more computer processors to: (i) use a first set of electron beam parameters to cause the first detector to acquire an electron microscope image of the surface of the specimen; (ii) cause the second detector to acquire an energy-dispersive spectroscopy (EDS) spectrum from each of a plurality of positions or points on the surface of the specimen identified from the electron microscope image, wherein acquiring the plurality of EDS spectra uses a second set of electron beam parameters different from the first set of electron beam parameters; and (iii) generate a map of compositional differences across the specimen from the plurality of EDS spectra. Generally, the electron microscope image is acquired by backscattered electron (BSE) imaging using a scanning electron microscope (SEM). However, if the specimen includes a thin plate having a thickness of less than about 200 nm, or in some sample types less than about 100 nm (optionally thinned by ion beam milling), the electron microscope image may be acquired by transmission electron microscopy (TEM) using a transmission electron microscope. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above and various other aspects of the present invention will become apparent from the following description with reference to the accompanying drawings, which are given by way of example only and are not necessarily drawn to scale.

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DETAILED DESCRIPTION OF THE INVENTION

[0014] The following description is presented to enable a person skilled in the art to make and use the invention and is provided in the context of a particular application and its requirements. Various modifications to the described embodiments will be readily apparent to those skilled in the art, and the general principles herein may be applied to other embodiments. Accordingly, the present invention is not intended to be limited to the embodiments and examples shown, but is to be accorded the widest possible scope consistent with the features and principles shown and described. To understand the features of the present invention in more detail and fully, please refer to FIGS. 1 to 4 in conjunction with the following description.

[0015] In the description of the present invention in this specification, unless otherwise understood or stated implicitly or explicitly, a word that appears in the singular encompasses its plural equivalents, and a word that appears in the plural encompasses its singular equivalents. Further, unless otherwise understood or stated implicitly or explicitly, for any given component or embodiment described in this specification, any of the possible candidates or alternatives listed for that component can generally be used individually or in combination with each other. Additionally, it should be understood that the figures shown in this specification are not necessarily drawn to scale, and some of the elements may be drawn merely for the purpose of clarifying the present invention. Also, reference numerals may be repeated in various figures to indicate corresponding or similar elements. Additionally, unless otherwise understood or stated implicitly or explicitly, any listing of candidates or alternatives is merely illustrative and not limiting.

[0016] Unless otherwise defined, all other technical and scientific terms used herein shall have the meanings commonly understood by one of ordinary skill in the art to which this disclosure belongs. In case of conflict, the present specification, including definitions, will control. It will be understood that implicit “about” is present before quantitative terms referred to in the present disclosure so that minor and slight deviations are within the scope of the present teachings. When “substantially,” “nearly,” “about,” or similar words are explicitly used in combination with a particular value, a variation of less than 10% of that value is always intended, unless otherwise specified. Similarly, the use of “comprise,” “comprises,” “comprising,” “contain,” “contains,” “containing,” “include,” “includes,” and “including” is not intended to be limiting. As used herein, “a” or “an” may refer to “at least one” or “one or more.” Also, the use of “or” is inclusive, such that the phrase “A or B” applies when A applies, when B applies, or when both A and B apply.

[0017] Figure 3 is a very schematic view of an embodiment of a charged particle beam microscope system that can be used in conjunction with the method of the present disclosure. More specifically, FIG. 1 shows an embodiment of a Scanning Electron Microscope (SEM) 1. The microscope 1 includes an electron optical column 3 that creates a beam 5 of charged particles (in this case, an electron beam) propagating along a particle optical axis 5'. The electron optical column 3 is mounted within a vacuum chamber 7 that includes a specimen carrier 9 for holding and / or positioning a specimen 13 and an associated stage / actuator 11. The vacuum chamber 7 is evacuated using a vacuum pump (not shown). Using a voltage source (not shown), the specimen carrier 9, or at least the specimen 13, can be biased (floating) to a predetermined potential with respect to ground, if necessary.

[0018] The particle-optical column 3 comprises an electron source 17 (such as a Schottky emitter), electrostatic and / or magnetic lenses 19, 21 (generally more complex in structure than shown in the schematic here) for focusing the electron beam 5 onto the specimen 13, and a deflection unit 23 (shown schematically) for performing beam deflection / scanning of the beam 5. When the beam 5 impinges on the specimen 13 or is scanned across the specimen, it causes the emission of various kinds of “induced” emissions such as the emission of backscattered electrons or secondary electrons, and / or the emission of X-rays and / or cathodoluminescence (infrared photons, visible photons, and / or ultraviolet photons). One or more of these various radiations can then be sensed / recorded using one or more detectors, which can typically form an image, spectrum, diffractogram, etc. by assembling a “map” (or “matrix”) of detector outputs as a function of the scanning position on the specimen. Two such detectors 25, 27 are shown in FIG. 1. According to various embodiments of the present disclosure, the detector 25 may be an X-ray detector (such as an SDD or Si(Li) sensor), and the detector 27 may be a detector for backscattered electrons emitted from the specimen 13 upon collision of the electron beam 5 onto the specimen. The detector 27 may be a segmented electron detector having a plurality of independent detection segments (e.g., quadrants) arranged around a central aperture 29 (which allows passage of the electron beam 5). These are merely examples, and those skilled in the art will understand that other detector types, numbers, and shapes / configurations are possible.

[0019] The electron microscope system 1 further includes a controller / computer processing unit 31 for controlling, among other things, lenses 19 and 21, deflection unit 23, and detectors 25, 27, and for displaying information collected from detectors 25, 27 on a display unit 33 (such as a flat panel display). Such control is performed via a control line (bus) 31'. A controller 31 (or another controller) can be further used to perform various mathematical processes such as combining, integrating, subtracting, false coloring, edge enhancement, and other processes known to those skilled in the art. Additionally, an automatic recognition process (such as used for particle analysis or grain analysis) may be included in such processes.

[0020] FIG. 1 also shows a vacuum port 7', which can be opened to insert an item (component, specimen) into the interior of the vacuum chamber 7 and / or to remove an item from the interior, or an auxiliary device / module (not shown) can be attached to the vacuum port 7'. The microscope system 1 may include a plurality of such ports 7' as needed.

[0021] FIG. 4 is a flowchart of an algorithm workflow method 400 according to the present teachings for generating a composition map of a specimen using an electron microscope. In step 401, which is the first step of method 400, the beam parameters of the electron beam incident on the specimen are set to values suitable for electron microscope imaging such as backscattered electron (BSE) imaging. These electron beam parameters include the electron beam acceleration voltage and, in some embodiments, may include the beam current, and can be automatically set to predetermined values in step 401. According to some embodiments, the beam parameters set in step 401 and then used for imaging may be input by the user based on previous experience with specimens including materials, origins, and / or preparation methods similar to the specimen being analyzed. Generally, the beam parameters are selected and set such that an image having distinct and clear image features such as features corresponding to particle boundaries and / or grain boundaries is obtained.

[0022] In step 403 of method 400, using the electron beam parameters set in step 401, an electron microscope image such as a backscattered electron image is acquired. The image may include only a single image frame (i.e., there is no movement of the stage holding the specimen during image acquisition). Alternatively, the image may be a composite image generated by aligning, subsequently superimposing and / or merging a plurality of image frames obtained from a series of individual image frames corresponding to each position across the surface of the specimen. According to the present invention, the electron beam parameters selected in step 401 and subsequently used during the execution of step 403 will generally include a beam acceleration voltage of about 2 keV or less.

[0023] The next three steps, namely steps 405, 407, and 409, are essentially identical to steps 103, 105, and 107, respectively, as outlined in FIG. 1. Thus, if there is a background signal due to the specimen embedding agent (e.g., epoxy), in step 405, it is subtracted from the acquired backscattered electron signals that make up the image. In step 407, the background-corrected image is analyzed to identify spatially separated particles (if any) in the specimen and to determine the boundaries and stage coordinates of such particles. In step 409, the background-corrected image may be further analyzed to identify and determine the boundaries of individual grains within the specimen and to determine the stage coordinates of such grains. If the specimen image is small or consists of a small number of particles or grains, the user may visually identify the observable particles / grains by using a pointing device (e.g., a computer mouse) to indicate them or by drawing a line around such particles / grains, or manually identify the boundaries, particles, and grains visually on the graphical user interface display of the BSE image. Subsequently, the software may automatically convert the user input into the actual stage coordinates of the identified features on the actual surface of the specimen. Alternatively, particularly if the specimen image is large and / or complex, well-known digital edge detection techniques based on discontinuities in image brightness may be used to automatically determine the boundaries of grains and / or particles.

[0024] The identification accuracy of the particle boundaries and / or grain boundaries identified in steps 407 and 409 depends on the sharpness of the one or more electron backscattered images generated in step 403. For example, FIG. 5 is an image of the same specimen area as shown in FIG. 2, but here the electron beam parameters are set to values that optimize the image sharpness of the surface features, as in step 401 of method 400. As described above, the beam parameters used during step 401 preferably include a beam acceleration voltage of about 2 keV or less. Compared to FIG. 2, in FIG. 5 the image sharpness and feature resolution are improved, thereby reducing the uncertainty of the boundaries of particles 201 and 202, providing further details regarding the exposure of grain 202b on the surface of the specimen, and enabling the identification of cracks on the surface of particle 201. Further, the enhancement of the contrast change of particle 201 reveals a band that may suggest local compositional zoning. Thus, the boundaries between such bands may be classified as additional grain boundaries for subsequent compositional analysis.

[0025] Step 409 further includes selecting positions on the specimen surface for later analysis by energy dispersive X-ray spectroscopy (EDS). The number of such EDS analyses and the specific positions on the specimen at which to perform the analyses may be selected for the purpose of achieving a representative compositional analysis while achieving the desired resolution of compositional differences with a minimum amount of time. Thus, the number and positions of the analyses depend on the size of the specimen as well as the structural complexity and possible compositional complexity of the specimen. The structural complexity of the specimen can be estimated based on the observed particle boundaries, grain boundaries and / or striation boundaries.

[0026] Returning to the description of method 400 outlined in FIG. 4, step 411 involves changing the electron beam parameter values (from the values previously set in step 403) to a second set of values, which is different from the first set of values and is suitable for EDS compositional analysis. Generally, the values of the beam parameters used for EDS analysis may be selected to achieve sufficient signal intensity at each analysis point necessary to achieve the desired compositional resolution across the specimen in the shortest time. When the specimen is susceptible to damage by the electron beam, a further consideration in the selection may be to obtain a low-noise result without damaging the specimen. Finally, in step 413, an EDS compositional analysis at each location is obtained by measuring the energy spectrum of the X-rays emitted from each sampling location when the electron beam is applied to each sampling location. The EDS compositional analysis may include one or more of scanning the electron beam across the surface of the specimen and / or translating the specimen stage one or more times to expose various regions of the specimen surface to the electron beam. Generally, the electron beam parameters selected in step 411 and then used during the execution of step 413 include a beam acceleration voltage higher than the beam acceleration voltage previously used during the execution of step 401 to induce X-ray signals from most of the elements of interest. Roughly speaking, during EDS analysis, the beam acceleration voltage needs to be approximately twice (i.e., 2x) the binding energy of the element in order to obtain a usable number of X-rays from the atoms of the target element. Most elements of general interest have X-ray emission lines in the range of 0-5 keV, regardless of whether the emission lines arise from filling of inner shell orbits (e.g., elements such as O, Na, and Mg) or from filling of outer shell orbits of elements with a large atomic number (e.g., Au, Pt, U). However, since there are many overlapping X-ray emission lines in the energy region of 0-5 keV, analysts generally use a higher voltage (e.g., 25 keV) to excite the emission of multiple X-ray emission lines from transition metal elements with a larger atomic number and resolve ambiguous peaks.As an example, both S and Pb exhibit X-ray emission lines at 2.3 kV, but Pb also exhibits another emission line near 10 kV. Therefore, the separation of Pb and S usually requires the presence of both emission lines to accurately distinguish them. Similar to the rough rule of the 2x voltage described above, the problem of distinguishing such elements means that, to obtain the best results, most EDS operations should be performed using an electron beam acceleration voltage of 20 keV or higher. Therefore, according to a preferred embodiment of the present invention, an acceleration voltage of 20 - 30 keV is utilized when performing step 413.

[0027] The present invention has been described according to the illustrated embodiments, but those skilled in the art will readily recognize that there may be modifications to those embodiments and that such modifications are within the scope of the present invention. Therefore, those skilled in the art can make many modifications without departing from the scope of the appended claims.

Claims

1. A method for mapping differences in composition within a specimen, comprising: acquiring an electron backscattered image of the surface of the specimen using a first set of electron beam parameters; identifying a plurality of positions or points in regions on the specimen to be analyzed by energy dispersive X-ray spectroscopy (EDS) from the electron backscattered image; acquiring an EDS spectrum from each of the identified positions or points using a second set of electron beam parameters different from the first set of electron beam parameters; generating a map of differences in composition across the specimen from the plurality of EDS spectra.

2. The first set of electron beam parameters is selected to optimize the sharpness and spatial resolution of the electron backscattered image, and the second set of electron beam parameters is selected to achieve a desired compositional resolution. The method according to claim 1.

3. The method according to claim 1 or 2, wherein identifying the plurality of positions or regions includes automatically identifying either particle boundaries or grain boundaries by digital image analysis.

4. The first set of electron beam parameters includes the use of an electron beam acceleration voltage of 2 keV or less, and the second set of electron beam parameters includes the use of an electron beam acceleration voltage in the range of 20 - 30 keV. The method according to claim 1 or 2.

5. An electron source and an electron optical column, a sample stage within a vacuum chamber for supporting a sample of the specimen, a first detector for detecting electrons backscattered from the specimen upon collision of an electron beam with the specimen, a second detector for detecting X-rays emitted from the specimen upon collision of the electron beam with the specimen, one or more computer processors including executable instructions which, when executed by the one or more computer processors, cause the one or more computer processors to acquire, using a first set of electron beam parameters, an electron backscattered image of the surface of the specimen at the first detector Causing the second detector to acquire an energy-dispersive X-ray spectroscopy (EDS) spectrum from each of a plurality of positions or points on the surface of the specimen identified from the electron backscattered image, wherein acquiring the plurality of EDS spectra uses a second set of electron beam parameters that is different from the first set of the electron beam parameters, and generating a map of differences in composition across the specimen from the plurality of EDS spectra, one or more computer processors configured to operate so as to perform the foregoing, an electron microscope system comprising the one or more computer processors and **Claim 6** When executed by the one or more computer processors, the executable instructions cause the one or more computer processors to set a first set of electron beam parameters in the electron source and the electron optical column to values that optimize the sharpness and spatial resolution of the electron backscattered image, and set a second set of electron beam parameters in the electron source and the electron optical column to values that achieve a desired compositional resolution, the electron microscope system according to claim 5, the executable instructions further causing the one or more computer processors to operate so as to perform the foregoing **Claim 7** When executed by the one or more computer processors, the executable instructions cause the one or more computer processors to further operate to identify either particle boundaries or grain boundaries within the specimen by digital image analysis of the electron backscattered image, the electron microscope system according to claim 5 or 6 **Claim 8** When executed by the one or more computer processors, the executable instructions cause the one or more computer processors to set the electron beam acceleration voltage of the first set of electron beam parameters to a value of 2 keV or less, and set the electron beam acceleration voltage of the second set of electron beam parameters to a value within the range of 20 to 30 keV, the electron microscope system according to claim 5 or 6, the executable instructions further causing the one or more computer processors to operate so as to perform the foregoing **Claim 9** One or more computer-readable storage media having executable instructions defined therein, wherein when executed by one or more computer processors, the executable instructions cause the one or more computer processors to acquire an electron backscattered image of the surface of a specimen using a first set of electron beam parameters at a first detector of an electron microscope system Identifying a plurality of positions or points in regions on the specimen that are later analyzed by the electron microscope system using energy-dispersive X-ray spectroscopy (EDS) from the electron backscattered image; Using a second set of electron beam parameters different from the first set of electron beam parameters to cause a second detector of the electron microscope system to acquire an EDS spectrum from each of the identified positions or points; Generating a map of compositional differences across the specimen from the plurality of EDS spectra, one or more computer-readable storage media operative to perform.

10. When the executable instructions are executed by the one or more computer processors, the one or more computer processors are Causing the electron source and electron optical column of the electron microscope to set a first set of the electron beam parameters to values that optimize the sharpness and spatial resolution of the electron backscattered image; Causing the electron source and the electron optical column to set a second set of the electron beam parameters to values that achieve a sufficient EDS signal intensity necessary to achieve a desired compositional resolution in a minimum amount of time from each identified position or point, the one or more computer-readable storage media according to claim 9, further operative to perform.

11. When the executable instructions are executed by the one or more computer processors, the one or more computer processors are Further causing the one or more computer processors to identify either particle boundaries or grain boundaries within the specimen by digital image analysis of the electron backscattered image, the one or more computer-readable storage media according to claim 9 or 10.

12. When the executable instructions are executed by the one or more computer processors, the one or more computer processors are Setting the electron beam acceleration voltage of the first set of the electron beam parameters to a value of 2 keV or less; Setting the electron beam acceleration voltage of the second set of the electron beam parameters to a value within the range of 20 - 30 keV, the one or more computer-readable storage media according to claim 9 or 10, further operative to perform.

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