Patent Publication Number: US-2023135601-A1

Title: Phase Analyzer, Sample Analyzer, and Analysis Method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2021-179616, filed Nov. 2, 2021, the disclosure of which is hereby incorporated by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a phase analyzer, a sample analyzer, and an analysis method. 
     Description of Related Art 
     In a scanning electron microscope equipped with an X-ray detector such as an energy-dispersive X-ray spectrometer (EDS) or a wavelength-dispersive X-ray spectrometer (WDS), spectrum imaging data, in which a position on a sample and an X-ray spectrum are associated with each other, can be obtained. As a technique for determining a distribution of compounds by using spectrum imaging data, phase analysis is known. 
     For example, JP-A-2018-200270 discloses a phase analyzer in which a graph illustrating an X-ray intensity of each element and a concentration of each element by means of areas is displayed along with a phase map showing a distribution of compounds to facilitate understanding of characteristics of compositions of the compounds. 
     In the phase analysis, favorable phase analysis results cannot be obtained unless analysis conditions are appropriate. For that reason, it is required to change analysis conditions and repeat phase analysis to find appropriate conditions. However, when the analysis conditions are changed and the phase analysis is repeated, in order to confirm the phase analysis results obtained prior to the condition change, the phase analysis has to be performed again under the original conditions. 
     SUMMARY OF THE INVENTION 
     A phase analyzer according to a first aspect of the invention includes: 
     a data acquisition unit that acquires spectrum imaging data in which a position on a sample is associated with a spectrum of a signal from the sample; 
     a phase analysis unit that performs phase analysis based on the spectrum imaging data; 
     a display control unit that displays results of the phase analysis on a first screen; and 
     a condition reception unit that receives an operation for changing a condition for the phase analysis, 
     when the condition reception unit has received the operation for changing the condition, the phase analysis unit performing phase analysis under the changed condition, 
     the display control unit displaying on a second screen the results of the phase analysis performed under the changed condition, and 
     when a predetermined operation has been performed, the display control unit reflecting on the first screen the results of the phase analysis displayed on the second screen. 
     A sample analyzer according to a second aspect of the invention includes the above phase analyzer. 
     An analysis method according to a third aspect of the invention includes: 
     acquiring spectrum imaging data in which a position on a sample is associated with a spectrum of a signal from the sample; 
     performing phase analysis based on the spectrum imaging data; 
     displaying results of the phase analysis on a first screen; 
     when a condition for the phase analysis has been changed, performing phase analysis under the changed condition, and displaying on a second screen the results of the phase analysis performed under the changed condition; and 
     reflecting on the first screen the results of the phase analysis displayed on the second screen when a predetermined operation has been performed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a diagram illustrating a configuration of a sample analyzer including a phase analyzer according to an embodiment of the invention. 
         FIG.  2    is a diagram illustrating a configuration of a phase analyzer according to an embodiment of the invention. 
         FIG.  3    is a diagram for describing a hierarchical clustering method. 
         FIG.  4    is a diagram for describing a hierarchical clustering method. 
         FIG.  5    is a graph illustrating a relationship between the number of clusters and linkage criteria. 
         FIG.  6    is a graph illustrating a relationship between the number of clusters and curvatures. 
         FIG.  7    is a table for describing a first database. 
         FIG.  8    is a table for describing a second database. 
         FIG.  9    is a diagram for describing a process of grouping edge phases. 
         FIG.  10    is a diagram for describing a method for determining edge phases. 
         FIG.  11    is a diagram illustrating an example of an analysis screen. 
         FIG.  12    is a diagram illustrating an example of a preview screen. 
         FIG.  13    is a diagram illustrating an example of a preview screen. 
         FIG.  14    is a diagram for describing a process of determining candidates for the number of clusters. 
         FIG.  15    is a diagram illustrating an example of a candidate list screen. 
         FIG.  16    is a diagram schematically illustrating a state in which one phase map group is selected on a candidate list screen. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     A phase analyzer according to an embodiment of the invention includes: 
     a data acquisition unit that acquires spectrum imaging data in which a position on a sample is associated with a spectrum of a signal from the sample; 
     a phase analysis unit that performs phase analysis based on the spectrum imaging data; 
     a display control unit that displays results of the phase analysis on a first screen; and 
     a condition reception unit that receives an operation for changing a condition for the phase analysis, 
     when the condition reception unit has received the operation for changing the condition, the phase analysis unit performing phase analysis under the changed condition, 
     the display control unit displaying on a second screen the results of the phase analysis performed under the changed condition, and 
     when a predetermined operation has been performed, the display control unit reflecting on the first screen the results of the phase analysis displayed on the second screen. 
     In the phase analyzer, the phase analysis results before the change of the condition for phase analysis can be displayed on the first screen, and the phase analysis results after the change of the condition for the phase analysis can be displayed on the second screen. For that reason, in the phase analyzer, even if the condition is repeatedly changed, the phase analysis results before the change of the condition can be easily confirmed. 
     A sample analyzer according to an embodiment of the invention includes the above phase analyzer. 
     An analysis method according to an embodiment of the invention includes: 
     acquiring spectrum imaging data in which a position on a sample is associated with a spectrum of a signal from the sample; 
     performing phase analysis based on the spectrum imaging data; 
     displaying results of the phase analysis on a first screen; 
     when a condition for the phase analysis has been changed, performing phase analysis under the changed condition, and displaying on a second screen the results of the phase analysis performed under the changed condition; and 
     reflecting on the first screen the results of the phase analysis displayed on the second screen when a predetermined operation has been performed. 
     In the analysis method, the results of the phase analysis before the change of the condition for the phase analysis can be displayed on the first screen, and the results of the phase analysis after the change of the condition can be displayed on the second screen. For that reason, in the analysis method, even if the condition is repeatedly changed, the results of the phase analysis before the change of the condition can be easily confirmed. 
     Preferred embodiments of the invention will be described in detail below with reference to the figures. It is noted that the embodiments described below do not unduly limit the scope of the invention described in the claims. In addition, all of the components described below are not necessarily essential requirements of the invention. 
     1. Analyzer 
     First, a phase analyzer according to an embodiment of the invention will be described with reference to the figures.  FIG.  1    is a diagram illustrating a configuration of a sample analyzer  100  including a phase analyzer  80  according to an embodiment of the invention. 
     The sample analyzer  100  is a scanning electron microscope equipped with an X-ray detector  70 . In the sample analyzer  100 , by scanning a sample S with an electron probe EP, spectrum imaging data in which a position on the sample S is associated with an X-ray spectrum can be acquired. 
     As illustrated in  FIG.  1   , the sample analyzer  100  includes an electron gun  10 , a condenser lens  20 , a scanning coil  30 , an objective lens  40 , a sample stage  50 , a secondary electron detector  60 , the X-ray detector  70 , and the phase analyzer  80 . 
     The electron gun  10  emits an electron beam. The electron gun  10 , for example, accelerates electrons emitted from a cathode at an anode to emit the electron beam. 
     The condenser lens  20  and the objective lens  40  focus the electron beam emitted from the electron gun  10  to form the electron probe EP. A probe diameter and a probe current thereof can be controlled by the condenser lens  20 . 
     The scanning coil  30  two-dimensionally deflects the electron probe EP. By two-dimensionally deflecting the electron probe EP with the scanning coil  30 , the sample S can be scanned with the electron probe EP. 
     The sample stage  50  can hold the sample S. The sample stage  50  has a moving mechanism for moving the sample S. 
     The secondary electron detector  60  detects secondary electrons emitted from the sample S when the sample S is irradiated with the electron beam. The sample S is scanned by the electron probe EP, and the secondary electrons emitted from the sample S are detected by the secondary electron detector  60 , so that a secondary electron image can be obtained. Also, the sample analyzer  100  may include a backscattered electron detector that detects backscattered electrons emitted from the sample S when the sample S is irradiated with the electron beam. 
     The X-ray detector  70  detects characteristic X-rays emitted from the sample S when the sample S is irradiated with the electron beam. The X-ray detector  70  is, for example, an energy-dispersive X-ray detector. Also, the X-ray detector  70  may be a wavelength-dispersive X-ray spectroscope. Spectrum imaging data can be obtained by scanning the sample S with the electron probe EP and detecting characteristic X-rays emitted from the sample S with the X-ray detector  70 . 
     Spectrum imaging data is data in which positions (coordinates) on a sample and spectra based on signals from the sample are associated with each other. In the sample analyzer  100 , data in which positions on the sample S are associated with X-ray spectra can be obtained as the spectrum imaging data. In the sample analyzer  100 , while the sample S is scanned with the electron probe EP, the X-ray spectra are collected for each pixel, and the positions on the sample S (coordinates of pixels) and the X-ray spectra are associated with each other and stored. 
     The phase analyzer (information processing device)  80  performs phase analysis using the spectrum imaging data and displays phase analysis results. In addition, the phase analyzer  80  can analyze and edit the phase analysis results. 
       FIG.  2    is a diagram illustrating a configuration of the phase analyzer  80 . 
     As illustrated in  FIG.  2   , the phase analyzer  80  includes a processing unit  800 , an operation unit  810 , a display unit  820 , and a storage unit  830 . 
     The operation unit  810  is used by a user to input operation information and outputs input operation information to the processing unit  800 . Functions of the operation unit  810  can be implemented by input devices such as a keyboard, a mouse, buttons, a touch panel, and a touch pad. 
     The display unit  820  is for displaying images generated by the processing unit  800 , and its functions can be realized by a display such as a liquid crystal display (LCD) or a cathode ray tube (CRT). 
     The storage unit  830  stores programs and various data for causing a computer to function as each part of the processing unit  800 . In addition, the storage unit  830  also functions as a work area for processing unit  800 . Functions of the storage unit  830  can be realized by a hard disk, a random access memory (RAM), or the like. 
     The processing unit  800  executes the programs stored in the storage unit  830 , and thus functions as a data acquisition unit  802 , a condition reception unit  804 , a phase analysis unit  806 , and a display control unit  808 , which will be described below. Functions of the processing unit  800  can be realized by executing a program using hardware such as various processors (a CPU, a DSP, etc.) and ASIC (a gate array, etc.). The processing unit  800  includes the data acquisition unit  802 , the condition reception unit  804 , the phase analysis unit  806 , and the display control unit  808 . 
     The data acquisition unit  802  acquires the spectrum imaging data obtained by analyzing the sample S with the sample analyzer  100 . 
     The condition reception unit  804  receives an operation for changing conditions for phase analysis. 
     The phase analysis unit  806  performs the phase analysis by performing multivariate analysis on the spectrum imaging data. As the phase analysis results, a phase map, a phase spectrum, an area fraction, a phase name (a compound name and compositional information), and the like are obtained. The phase map is an image that shows a distribution of compounds. 
     The display control unit  808  causes the display unit  820  to display the phase analysis results. 
     2. Analysis Method 
     2.1. Acquisition of Spectrum Imaging Data 
     The data acquisition unit  802  acquires the spectrum imaging data obtained by analyzing the sample S with the sample analyzer  100 . In the sample analyzer  100 , the sample S is scanned with the electron probe EP to detect the X-rays emitted from the sample S with the X-ray detector  70 , and the X-ray spectrum data is acquired at each detected position. The detected positions (coordinates on the sample S) and the X-ray spectrum data are associated with each other and stored. Thus, the spectrum imaging data can be obtained. 
     2.2. Reception of Conditions for Phase Analysis 
     The condition reception unit  804  receives the conditions for phase analysis. The conditions for phase analysis are, for example, the number of phases. When the user performs an operation to specify the number of phases on the operation unit  810 , the condition reception unit  804  receives an operation for changing the conditions for phase analysis and acquires information on the number of phases specified by the user. 
     Also, the conditions for phase analysis are not limited to the number of phases. For example, as the conditions for phase analysis, conditions such as smoothing, pixel binning, normalization of spectrum intensity, and parameters (a size of a region D and a threshold) in a process of combining phases, which will be described later, can be exemplified. 
     Smoothing is a process of blurring an image. Pixel binning is a process of regarding a plurality of adjacent pixels as one pixel in spectrum imaging data acquired for each pixel. Normalization of spectrum intensity refers to increasing intensity of a peak of interest in a spectrum relative to other peaks. Thus, the peak of interest is treated as a feature of analysis target data in multivariate analysis, which will be described later. The parameters in the process of combining phases will be described later in a “&lt;process of combining edge phases&gt;.” Varying these conditions alters the phase analysis results that are obtained. 
     2.3. Phase Analysis 
     The phase analysis unit  806  performs phase analysis on spectrum imaging data. The phase analysis is performed using, for example, multivariate analysis. As the multivariate analysis, methods such as self-organizing maps (SOM), a hierarchical clustering method, a K-means method, principal component analysis, singular value decomposition, non-negative matrix decomposition, vertex component analysis, and the like can be exemplified. Also, these methods may be used in combination. 
     The phase analysis unit  806  performs the phase analysis in accordance with the conditions received by the condition reception unit  804 . For example, in a case in which the condition reception unit  804  receives an operation for specifying the condition for the number of phases, the phase analysis unit  806  performs the phase analysis such that the number of phase maps corresponding to the designated number of phases is created. 
     Also, in a case in which the number of phases is not specified, the phase analysis unit  806  may estimate the number of phases using multivariate analysis. The phase analysis unit  806 , for example, performs cluster analysis on the spectrum imaging data to estimate the number of phases. Cluster analysis is a type of multivariate analysis and is unsupervised learning of collecting similar data in data groups and classifying it. Here, as the cluster analysis, a case of estimating the number of phases by combining the self-organizing maps and a hierarchical clustering method will be described. 
     The phase analysis unit  806  first creates the self-organizing maps of the spectrum imaging data. The phase analysis unit  806  learns the self-organizing maps using spectrum data of each pixel constituting the spectrum imaging data as input vectors. This creates a map space that associates the input vectors with each other. In the map space, a degree of similarity of spectrum data is represented by a distance. The phase analysis unit  806  sorts the spectrum data into groups based on the distance on the map space and creates clusters. A cluster is a collection of similar input vectors (spectrum data). 
     The phase analysis unit  806  uses the clusters obtained using the self-organizing maps as minimum unit clusters and merges the minimum unit clusters using a hierarchical clustering method to create new clusters. 
       FIGS.  3  and  4    are diagrams for describing the hierarchical clustering method. 
     As illustrated in  FIGS.  3  and  4   , the phase analysis unit  806  merges the minimum unit clusters C 1 , C 2 , C 3 , C 4 , C 5 , C 6 , C 7 , C 8 , C 9 , and C 10  obtained from the self-organizing maps using the hierarchical clustering method to create new clusters. 
     Specifically, the phase analysis unit  806  obtains distances (dissimilarities) between the minimum unit clusters C 1 , C 2 , C 3 , C 4 , C 5 , C 6 , C 7 , C 8 , C 9 , and C 10  and merges combinations thereof in descending order of the distance. A process of merging can be represented by a dendrogram. A distance required to merge two clusters is referred to as a linkage criterion. 
     As illustrated in  FIG.  4   , new clusters can be created by cutting the dendrogram at a threshold T. In the hierarchical clustering method, by adjusting the threshold T, any number of clusters can be created. In the illustrated example, by cutting the dendrogram at the threshold T, four clusters are created. 
       FIG.  5    is a graph illustrating a relationship between the number of clusters and linkage criteria. 
     The phase analysis unit  806  obtains the linkage criteria between the minimum unit clusters C 1 , C 2 , C 3 , C 4 , C 5 , C 6 , C 7 , C 8 , C 9 , and C 10  and creates the graph (function) indicating the relationship between the number of clusters and the linkage criteria illustrated in  FIG.  5   . 
       FIG.  6    is a graph illustrating a relationship between the number of clusters and curvatures. 
     The phase analysis unit  806  creates the graph indicating the relationship between the number of clusters and the curvatures as illustrated in  FIG.  6    from the graph indicating the relationship between the number of clusters and the linkage criteria as illustrated in  FIG.  5   . Here, the curvature is a curvature at an arbitrary point of the function showing the relationship between the number of clusters and the linkage criteria. A curvature R at a point (a, f(a)) of y=f(x) can be obtained by the following formula. 
     
       
         
           
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     The phase analysis unit  806  obtains the curvatures for each number of clusters and determines priority based on the curvatures. The priority can be expressed, for example, as a ratio of the largest curvature among the curvatures obtained for each number of clusters as a reference. The greater the curvature, the higher the priority. 
     In the example illustrated in  FIG.  6   , since the curvature is the largest when the number of clusters is “4,” the number of clusters is determined to be “4.” That is, the phase analysis unit  806  estimates the number of phases to be four. 
     The phase analysis unit  806  performs the phase analysis in accordance with the conditions for phase analysis and creates the phase maps as a result of the phase analysis. In the example illustrated in  FIG.  6   , since the number of phases is estimated to be four, the phase analysis unit  806  creates a phase map group consisting of four phase maps. 
     The phase analysis unit  806  further creates a phase spectrum from each phase map. A phase spectrum is a spectrum obtained by averaging (or integrating) spectra of all pixels that constitute a phase map. Further, the phase analysis unit  806  can perform a process of naming a phase for each phase map (labeling process), a process of obtaining an area fraction of each phase, a process of grouping edge phases, and the like. Each process performed by the phase analysis unit  806  will be described in detail below. 
     Labeling Process 
     A phase name is determined using two databases (a first database and a second database). Here, a case in which a compound name is used as a phase name will be described. 
       FIG.  7    is a table for describing the first database, and  FIG.  8    is a table for describing the second database. 
     In the first database, as illustrated in  FIG.  7   , classification names (compound names), spectrum data, and quantitative results are registered. The first database may be created by registering acquired spectra by the user, or may be a publicly available or commercially available spectrum database. A classification name is a compound name assumed from a quantitative result. Spectrum data is data of a acquired X-ray spectrum. The quantitative result is a result of performing quantitative calculation on the acquired spectrum. For example, in the first database, as data No. 1, SiO 2  is registered as a classification name, SiO 2  spectrum data is registered as data of a spectral shape, and Si: 47.3269% and O: 52.6731% are registered as a quantitative result. 
     In the second database, as illustrated in  FIG.  8   , compound names and composition information are registered. Composition information is calculated from a compound name. For example, in the second database, as data No. 1, SiO 2  is registered as a compound name, and Si: 46.744559% and O: 53.255441% are registered as composition information. 
     The phase analysis unit  806  searches for, from the first database and the second database, data that has a high degree of matching with phase data (a phase spectrum and a quantitative result) serving as a naming target and a compound name of the data with a high degree of agreement is used as a phase name thereof. 
     Also, the phase analysis unit  806  may perform qualitative and quantitative analysis on phase spectra to obtain phase composition information and may name phases based on the composition information. 
     Area Fraction 
     The phase analysis unit  806  calculates an area fraction of each phase map. The area fraction can be expressed as a ratio of an area of each phase to an area of the entire map. 
     Process of Combining Edge Phases 
     In the phase map, there are cases where two phases cannot be separated at a boundary of the two phases and another phase seems to be present at the boundary between the two phases. Another phase present on the boundary between these two phases is referred to as an edge phase. This edge phase is not actually present, and thus in a case in which a plurality of edge phases are present, the plurality of edge phases are combined into one. 
       FIG.  9    is a diagram for describing a process of grouping edge phases.  FIG.  9    illustrates a phase map M 1  of a first phase, a phase map M 2  of a second phase, a phase map M 3  of a third phase, a phase map M 4  of a fourth phase, a phase map M 5  of a fifth phase, a phase map M 6  of a sixth phase, a phase map M 7  of a seventh phase, and a phase map M 8  of an eighth phase. 
     Here, the sixth phase and the seventh phase indicate edges of the first phase. Also, the eighth phase indicates edges of the fifth phase. For that reason, the phase map M 6  of the sixth phase, the phase map M 7  of the seventh phase, and the phase map M 8  of the eighth phase are combined to create a phase map Edge. Thus, a plurality of edge phases can be combined into one phase map. 
     The phase analysis unit  806  determines edge phases from a plurality of phase maps that constitute a phase map group. Here, a case in which determination is made by focusing on the characteristic that pixels of other phases are often present around pixels of edge phases will be described. 
       FIG.  10    is a diagram for describing a method for determining an edge phase. A phase A, a phase B, and a phase C are illustrated in  FIG.  10   . Here, a case of determining whether or not the phase C is an edge phase will be described. 
     Focusing on one pixel C 0  of pixels belonging to phase C, data of the region D around the pixel C 0  is cut out. In the illustrated example, the region D is a 5×5 region. A size of the cutout region D can be set, for example, on a preview screen, which will be described later. 
     Next, the number of pixels in each phase included in the region D is counted. In the example illustrated in  FIG.  10   , the phase A has 8 pixels, the phase B has 12 pixels, and the phase C has 5 pixels. 
     Next, it is determined whether a phase with the largest number of pixels matches a phase of the pixel C 0 . In a case in which they do not match each other, the pixel C 0  is determined to be an edge-like pixel. In a case in which they match each other, the pixel C 0  is not determined to be an edge-like pixel. Here, since the phase with the largest number of pixels does not match the phase of the pixel C 0 , the pixel C 0  is determined to be an edge-like pixel. 
     The process of cutting out the region D, the process of counting the number of pixels, and the process of determining whether or not the phase with the largest number of pixels matches the phase of the pixel of interest is performed for all pixels belonging to the phase C. Then, a proportion between the total number of pixels belonging to the phase C and the number of pixels determined to be edge-like pixels is calculated. As a result, in a case in which the proportion exceeds a threshold, the phase C is determined as an edge phase. On the other hand, in a case in which the proportion is equal to or less than the threshold, the phase C is not determined to be an edge phase. The threshold can be set on a preview screen, which will be described later. 
     Here, the case of determining whether or not the phase C is an edge phase has been described, but a process of determining whether or not all phases are edge phases is performed. As a result, the edge phases can be extracted from the phase map group. 
     Also, the method for determining the edge phase is not limited thereto. For example, it may be determined whether or not a phase is an edge phase from a phase shape, or whether or not it is an edge phase may be determined from a phase spectrum. 
     2.4. Display 
     2.4.1. Display of Analysis Screen 
     The display control unit  808  displays the phase analysis results performed by the phase analysis unit  806  on an analysis screen (an example of the first screen). The analysis screen is displayed on the display unit  820 . 
       FIG.  11    is a diagram illustrating an example of an analysis screen  2  (a GUI screen). 
     A plurality of phase maps and phase spectra are displayed on the analysis screen  2 . The analysis screen  2  also displays names of each phase, area fractions of each phase, and quantitative results thereof. Further, in a region  202  of the analysis screen  2 , an image obtained by synthesizing each phase map and SEM image is displayed. 
     On the analysis screen  2 , it is possible to analyze and edit the phase analysis results. For example, on the analysis screen  2 , qualitative and quantitative analysis of phase spectra, phase combining, phase color changes, phase name changes, and the like can be performed. 
     On the analysis screen  2 , qualitative and quantitative analysis of phase spectra can be performed under various conditions. By performing qualitative and quantitative analysis of phase spectra, phases can be renamed and compared to other phases. 
     On the analysis screen  2 , a plurality of phase maps can be combined to form one phase map. For example, phase maps with similar distributions can be combined into one phase map, or a plurality of phases with similar compositions can be combined into one phase. Also, a plurality of edge phases can be combined into one phase map. 
     On the analysis screen  2 , colors of phase maps selected by the user can be changed to desired colors. This makes it easier to see the phase maps. 
     Also, on the analysis screen  2 , phase names can be changed. For example, phase names may be changed based on results of the qualitative and quantitative analysis of phase spectra. 
     2.4.2. Display of Preview Screen 
     The display control unit  808  displays a preview screen (an example of the second screen) along with the analysis screen  2 . For example, in a case in which the user changes the phase analysis conditions after analyzing and editing the phase analysis results on the analysis screen  2 , the conditions can be changed on the preview screen. Also, on the preview screen, results of the phase analysis performed under the changed conditions are displayed. 
     On the preview screen  4 , change of the conditions and confirmation of the results of the phase analysis performed under the changed conditions are repeatedly performed, and in a case in which appropriate phase analysis results are obtained, the phase analysis results displayed on the preview screen  4  can be applied to the analysis screen  2 . 
       FIG.  12    is a diagram illustrating an example of the preview screen  4 . 
     On the preview screen  4 , a slider  402  for the user to set the number of clusters (number of phases), a button  404  for automatically setting the number of clusters, an information display region  406  in which information for setting the number of clusters is displayed, a slider  408  for setting an edge determination level (region D) in the process of determining the edge phases, an analysis result display region  410  in which phase maps as a result of the phase analysis are displayed, an apply button  412 , and a close button  414  are displayed. 
     The slider  402  is a GUI component for the user to set the number of clusters. Also, the GUI component for setting the number of clusters is not limited to the slider  402 . The button  404  is a GUI component for causing the phase analysis unit  806  to set the number of clusters. By pressing the button  404 , the number of clusters is set to the number of clusters estimated by the phase analysis unit  806 . 
     Information for estimating the number of phases (number of clusters) is displayed in the information display region  406 . In the illustrated example, a dendrogram showing a process of merging clusters using the hierarchical clustering method is displayed. By checking the dendrogram, the number of clusters can be estimated. For example, a line indicating the threshold T corresponding to the number of clusters set with the slider  402  may be displayed on the dendrogram. 
     Also, the information displayed in the information display region  406  is not limited to the dendrogram. For example, the information display region  406  may display a graph indicating the relationship between the linkage criteria and the number of clusters illustrated in  FIG.  5   . Also, the information display region  406  may display both of the dendrogram and the graph indicating the relationship between the linkage criteria and the number of clusters. 
     Also, the information display region  406  may not be displayed on the preview screen  4 . For example, the information display region  406  may be displayed on a screen other than the preview screen  4 . 
     The slider  408  is a GUI component for setting the edge determination level, that is, for setting the region D in the above-described process for determining the edge phases. Also, the GUI component for setting the edge determination level (region D) is not limited to the slider  408 . 
     On the preview screen  4 , as described above, the number of clusters can be set with the slider  402 , and the edge determination level can be set with the slider  408 . In this way, on the preview screen  4  illustrated in  FIG.  12   , the phase analysis conditions that affect the number of phases can be changed. 
     Although not shown, the preview screen  4  may display a GUI component for setting a threshold in the process of determining the edge phases. 
     The analysis result display region  410  is a region for displaying the phase analysis results. In the illustrated example, phase maps are displayed. Also, in addition to the phase maps, the analysis result display region  410  may display phase spectra, results of qualitative and quantitative analysis (composition information), phase name information (compound names), and the like. These pieces of information may be displayed near the phase maps, or displayed using tooltips on the phase maps. 
     On the preview screen  4 , the phase analysis conditions can be changed by using the slider  402  to change the number of clusters, and by using the slider  408  to change the edge determination level (region D). In this case, the display control unit  808  changes the phase analysis results displayed in the analysis result display region  410  of the preview screen  4  without changing the phase analysis results displayed on the analysis screen  2 . That is, the analysis screen  2  displays the phase analysis results from before the conditions are changed, and the preview screen  4  displays the phase analysis results from after the conditions are changed. 
     The apply button  412  is a GUI component for applying the phase analysis results displayed on the preview screen  4  to the analysis screen  2 . The user presses the apply button  412  via the operation unit  810 , and thus the phase analysis results displayed on the preview screen  4  are reflected on the analysis screen  2 . That is, the results of the phase analysis performed under the changed conditions displayed on the preview screen  4  are displayed on the analysis screen  2 . As a result, analysis and editing of the phase analysis results can be performed on the analysis screen  2 . 
     The operation of pressing the apply button  412  has been performed here as an operation for applying the phase analysis displayed on the preview screen  4  to the analysis screen  2 , the operation for applying the phase analysis displayed on the preview screen  4  to the analysis screen  2  is not particularly limited. 
     The close button  414  is a GUI component for closing the preview screen  4  (a window displaying the preview screen  4 ). By performing an operation of pressing the close button  414 , the preview screen  4  is closed and the phase analysis results are discarded. 
     3. Operations 
     In the phase analyzer  80 , the analysis screen  2  and the preview screen  4  can be used to analyze and edit the phase analysis. 
     When the sample analyzer  100  collects signals from the sample S, and generates the spectrum imaging data, the data acquisition unit  802  acquires the spectrum imaging data. 
     The phase analysis unit  806  performs the phase analysis by performing multivariate analysis on the spectrum imaging data. For example, the phase analysis unit  806  creates the self-organizing maps of the spectrum imaging data and creates the minimum unit clusters. Next, the phase analysis unit  806  creates new clusters by merging the minimum unit clusters using the hierarchical clustering method. In this case, the phase analysis unit  806  estimates the number of clusters (the number of phases) based on the curvatures of the function indicating the relationship between the number of clusters and the linkage criteria as illustrated in  FIG.  6   . 
     The phase analysis unit  806  creates the phase map group consisting of the number of phase maps corresponding to the estimated number of phases. The phase analysis unit  806  obtains the compound names (phase names), the area fractions, and the phase spectra in addition to the phase map group. Further, the phase analysis unit  806  performs the qualitative and quantitative analysis on the phase spectra. 
     As illustrated in  FIG.  11   , the display control unit  808  causes the display unit  820  to display the analysis screen  2  on which the phase analysis results are displayed. In the example illustrated in  FIG.  11   , the display control unit  808  causes the analysis screen  2  to display the phase maps, the phase spectra, the quantitative results, and the compound names (phase names) as the phase analysis results. 
     On the analysis screen  2 , it is possible to analyze and edit the phase analysis results. For example, on the analysis screen  2 , qualitative and quantitative analysis of phase spectra, phase combining, change of colors of phases, and change of phase names can be performed. 
     Here, in a case in which that the phase analysis results are determined to be inappropriate as a result of the user confirming the phase analysis results on the analysis screen  2 , or as a result of analyzing and editing the phase analysis results, it is required to change the phase analysis conditions and perform new phase analysis. For example, in the phase analysis, if the number of phases set is not appropriate, appropriate phase maps cannot be obtained. 
     In the case of changing the conditions for the number of phases, although not shown, when the user operates a GUI component for opening the preview screen  4  on the analysis screen  2  via the operation unit  810 , the display control unit  808  causes the display unit  820  to display the preview screen  4  illustrated in  FIG.  12   . In this case, the same phase analysis results as the phase analysis results displayed on the analysis screen  2  are displayed in the analysis result display region  410  of the preview screen  4 . 
     Also, in the above description, the display control unit  808  has caused the preview screen  4  to be displayed when the user performs the operation to open the preview screen  4 , but the display control unit  808  may display the preview screen  4  simultaneously with the analysis screen  2 . 
     The information for setting the number of phases (the number of clusters) is displayed in the information display region  406  of the preview screen  4 . In the example illustrated in  FIG.  12   , the information display region  406  displays the dendrogram showing the process of merging the clusters by the hierarchical clustering method. The user can check the dendrogram displayed in the information display region  406  and estimate the number of clusters. 
     When the user operates the slider  402  via the operation unit  810  to change the number of clusters, the condition reception unit  804  receives the operation for changing the number of clusters. 
     The phase analysis unit  806  performs the phase analysis based on the information on the number of clusters received by the condition reception unit  804  and generates the phase map group configured of the number of phase maps corresponding to the number of clusters. Also, the phase analysis unit  806  obtains the compound names, the area fractions, and the phase spectra and performs the qualitative and quantitative analysis on the phase spectra. 
     The display control unit  808  displays the results of the phase analysis performed under the changed conditions of the number of phases on the preview screen  4  and updates the preview screen  4 . For that reason, the analysis screen  2  displays the phase analysis results (results of a first phase analysis) before the conditions of the number of phases are changed, and the preview screen  4  displays the phase analysis results from after the conditions of the number of phases are changed (the results of a second phase analysis). 
     When the user again operates the slider  402  via the operation unit  810  to change the number of clusters, the condition reception unit  804 , the phase analysis unit  806 , and the display control unit  808  repeat the above processes, and the results of the phase analysis performed under the changed conditions for the number of phases are displayed on the preview screen  4 . For that reason, the analysis screen  2  displays the phase analysis results from before the conditions for the number of phases are changed (results of the first phase analysis), and the preview screen  4  displays the phase analysis results from after the conditions of the number of phases are changed (results of a third phase analysis). 
     In a case in which the user determines that the results of the third phase analysis are appropriate, the user presses the apply button  412  via the operation unit  810 . Thus, the display control unit  808  causes the analysis screen  2  to display the results of the third phase analysis and updates the analysis screen  2 . Since the analysis screen  2  displays the results of the third phase analysis, the results of the third phase analysis can be analyzed and edited. 
     In addition, in a case in which the user determines that the results of the first phase analysis are appropriate after the results of the third phase analysis are confirmed, the user performs the operation of pressing the close button  414  via the operation unit  810 . Since the results of the first phase analysis are displayed on the analysis screen  2 , it is possible to analyze and edit the results of the first phase analysis. 
     Also, although the case of changing the number of phases has been described above, the phase analyzer  80  operates in the same way when changing the edge determination level (region D). Further, the preview screen  4  may be provided with a GUI component for changing other phase analysis conditions (smoothing, pixel binning, normalization of spectral intensity, parameters in a process of combining phases, etc.). In this case, the phase analyzer  80  operates in the same way as for changing the number of phases described above. 
     4. Effects 
     The phase analyzer  80  includes the data acquisition unit  802  that acquires the spectrum imaging data, the phase analysis unit  806  that performs the phase analysis based on the spectrum imaging data, the display control unit  808  that displays the phase analysis results on the analysis screen  2 , and the condition reception unit  804  that receives the operation for changing the phase analysis conditions. In addition, in the phase analyzer  80 , the phase analysis unit  806  performs the phase analysis under the changed phase analysis conditions when the condition reception unit  804  receives the operation for changing the phase analysis conditions, the display control unit  808  causes the preview screen  4  to display the results of the phase analysis performed under the changed phase analysis conditions, and in a case in which a predetermined operation is performed, it reflects the phase analysis results displayed on the preview screen  4  on the analysis screen  2 . 
     For that reason, in the phase analyzer  80 , the phase analysis results from before the conditions are changed can be displayed on the analysis screen  2  and the phase analysis results from after the conditions are changed can be displayed on the preview screen  4 . Accordingly, in the phase analyzer  80 , even if the conditions are repeatedly changed, the phase analysis results from before the conditions are changed can be easily confirmed. As a result, for example, the original phase analysis results can be easily reproduced even if the conditions are repeatedly changed. 
     Here, in order to determine optimum conditions for the phase analysis (number of phases, etc.), it is required to repeat performing the phase analysis under different conditions, creating the phase analysis results, and determining whether or not the results are appropriate. In some cases, whether or not the created phase analysis results are appropriate can be easily determined by visually observing the phase analysis results, and in some cases, it may not be determined unless the phase analysis results are analyzed and edited. As the number of phases increases, an amount of work involved in analysis and editing increases, and phases with complex compositions require a lot of labor, such as confirming the results of qualitative and quantitative analysis. 
     For example, after the analysis and the editing are performed, the phase analysis may be performed under different conditions, but no reasonable results may be obtained, and it can be determined that the initial conditions were optimal. In such a case, conventionally, in order to confirm the initial conditions, it was required to perform the same operations as the initial ones (condition setting, analysis, and editing). 
     On the other hand, in the phase analyzer  80 , change of the conditions and the phase analysis results from after the conditions are changed are displayed on the preview screen  4 , and the phase analysis results from before the conditions are changed are displayed on the analysis screen  2 , and thus the phase analysis results from before the conditions are changed can be easily reproduced. 
     In the phase analyzer  80 , the phase analysis unit  806  performs the phase analysis using the cluster analysis, and the display control unit  808  displays the dendrogram obtained by the cluster analysis on the preview screen  4 . For that reason, the phase analyzer  80  allows the user to logically estimate the number of phases. 
     5. MODIFIED EXAMPLES 
     5.1. First Modified Example 
     In the above-described embodiment, the phase analysis unit  806  creates both the phase maps and the phase spectra when the phase analysis conditions are changed, but the phase spectra may not be created while the preview screen  4  is displaying the phase analysis results, and the phase spectra may be created after the apply button  412  is pressed. 
     In this case, the phase maps are displayed on the preview screen  4 , but the phase spectra are not displayed. The phase analysis unit  806  creates the phase spectra at a timing when the apply button  412  on the preview screen  4  is pressed, and the display control unit  808  displays the created phase spectra on the analysis screen  2  together with the phase maps. 
     5.2. Second Modified Example 
     In the above-described embodiment, the phase analysis unit  806  estimates the number of phases (number of clusters) using the cluster analysis, and the display control unit  808  causes the information display region  406  of the preview screen  4  to display the dendrogram obtained by the cluster analysis. 
     On the other hand, for example, the phase analysis unit  806  may estimate the number of phases using principal component analysis, and the display control unit  808  may cause the information display region  406  of the preview screen  4  to display a scree plot created in the process of performing the principal component analysis. 
       FIG.  13    is a diagram illustrating an example of the preview screen  4 . 
     A scree plot is one of methods used to estimate the appropriate number of phases (number of components) in the principal component analysis. The scree plot is a graph obtained by plotting calculated principal components and their eigenvalues (variances) by executing the principal component analysis. The user can estimate the appropriate number of phases from a relationship between the number of phases and the eigenvalues. 
     In the phase analyzer  80 , the phase analysis unit  806  performs the phase analysis using the principal component analysis, and a display control unit  808  displays the scree plot obtained by the principal component analysis on the preview screen  4 . For that reason, the phase analyzer  80  allows the user to logically estimate the number of phases. 
     Also, the phase analysis unit  806  may perform the phase analysis using singular value decomposition, non-negative matrix decomposition, or vertex component analysis, and the display control unit  808  may display the scree plot obtained by the principal component analysis. 
     5.3. Third Modified Example 
     In the above-described embodiment, the phase analysis unit  806  has determined the number of clusters (the number of phases) from the graph indicating the relationship between the number of clusters and the curvatures illustrated in  FIG.  6   , but the phase analysis unit  806  may determine cluster number candidates from the graph illustrated in  FIG.  6   . 
       FIG.  14    is a diagram for describing the process of determining candidates for the number of clusters.  FIG.  14    illustrates a graph indicating the relationship between the number of clusters and the curvatures. 
     For example, the phase analysis unit  806  obtains the curvature for each number of clusters and determines the priority based on the curvature. The priority is expressed, for example, as the ratio of the largest curvature among the curvatures obtained for each number of clusters. The greater the curvature, the higher the priority. 
     In the example illustrated in  FIG.  14   , since the curvature is the largest in a case in which the number of clusters is “4,” it has the highest priority and is selected as a candidate  1 . Also, since the curvature is the second largest in a case in which the number of clusters is “5,” it has the second highest priority and is selected as a candidate  2 . In addition, since the curvature is the third largest in a case in which the number of clusters is “3,” it has the third highest priority and is selected as a candidate  3 . 
     From these results, the phase analysis unit  806  determines the case in which the number of phases is 4, the case in which the number of phases is 5, and the case in which the number of phases is 3 as candidates. 
     Here, the phase analysis unit  806  determines only the number of clusters with higher priority than a preset reference value of priority as candidates. For that reason, the case in which the number of clusters is “7” has the fourth largest curvature, but the priority is lower than the preset reference value, and thus it is excluded from the candidates. 
     Also, the phase analysis unit  806  may list a preset number of candidates for the number of phases. That is, in a case in which the number of candidates is set to three in advance, the phase analysis unit  806  lists three candidates for the number of phases in descending order of priority. 
     The phase analysis unit  806  creates phase map groups consisting of the number of phase maps corresponding to the determined number of phases for each candidate of the determined number of phases. 
     The display control unit  808  displays the number of phases and the phase map groups on a candidate list screen (an example of a third screen) for each candidate for the number of phases. The display control unit  808  displays the phase map groups in descending order of priority. 
       FIG.  15    is a diagram illustrating an example of a candidate list screen  6  for displaying phase map group candidates. 
     The display control unit  808  displays the phase analysis results performed by the phase analysis unit  806  described above on the candidate list screen  6  illustrated in  FIG.  15   . 
     The candidate list screen  6  illustrated in  FIG.  15    displays a phase map group in which the number of phases is four, a phase map group in which the number of phases is five, and a phase map group in which the number of phases is three. These three phase map groups are arranged in descending order of priority. 
     In addition, the display control unit  808  displays the compound names (phase names) and each area fraction. As the compound names, compound names determined by the phase analysis unit  806  or compound names input by the user are displayed. Although not shown, the candidate list screen  6  may display information for the user to select phase map groups, such as phase spectra, a dendrogram, and the like, in addition to the above-described phase names and area fractions. 
       FIG.  16    is a diagram schematically illustrating a state in which one phase map group is selected on the candidate list screen  6 . 
     On the candidate list screen  6 , the user can select one phase map group from a plurality of phase map group candidates displayed. For example, in a case in which the display unit  820  includes a touch panel (an example of the operation unit  810 ), the user performs an operation of touching a desired phase map group with a fingertip FG, so that the user can select one phase map group from the plurality of phase map groups displayed on the candidate list screen  6 . Also, the phase map group may be selected by operating a mouse or keyboard. 
     When the phase map group is selected, the display control unit  808  causes the analysis screen  2  to display the selected phase map group (phase analysis results). 
     The operation after the display control unit  808  causes the analysis screen  2  to display the phase analysis results is the same as in the above-described embodiment, and the description thereof will be omitted. 
     As described above, the phase analysis unit  806  performs the multivariate analysis on the spectrum imaging data to determine candidates for the number of phases and creates phase map groups consisting of the number of phase maps corresponding to the number of phases for each candidate, and the display control unit  808  displays the phase map groups on the candidate list screen  6  for each candidate. For that reason, the phase analyzer  80  can determine the candidates for the number of phases and can cause the display unit  820  to display the phase map groups configured of the number of phase maps corresponding to the number of phases for each candidate for the number of phases. Accordingly, the user can easily obtain favorable phase map groups. 
     In addition, in the phase analyzer  80 , the phase analysis unit  806  obtains the priority of the number of phases based on the results of the multivariate analysis and determines the candidates for the number of phases based on the priority. For that reason, the phase analyzer  80  does not require the user to specify the number of phases. 
     5.4. Fourth Modified Example 
     In the above-described embodiments, the case in which the sample analyzer  100  is a scanning electron microscope equipped with the X-ray detector  70  has been described, but the analyzer according to the invention is not limited thereto. For example, the analyzer according to the invention may be any device that can obtain spectra based on signals (X-rays, electrons, ions, etc.) from the sample S. The analyzer according to the invention is a transmission electron microscope equipped with an energy-dispersive X-ray spectrometer or a wavelength-dispersive X-ray spectrometer, an electron probe microanalyzer, an Auger microprobe, a photoelectron spectrometer, a focused ion beam device, or the like. 
     Also, the above-described embodiments and modified examples are merely examples, and the invention is not limited thereto. For example, the embodiments and modified examples can be combined as appropriate. 
     The invention is not limited to the above-described embodiments, and various modifications are possible. For example, the invention includes configurations that are substantially the same as the configurations described in the embodiments. Substantially same configurations mean configurations having the same functions, methods and results, or configurations having the same objectives and effects as those of the configurations described in the embodiments, for example. The invention also includes configurations obtained by replacing non-essential elements of the configurations described in the embodiments with other elements. The invention also includes configurations having the same effects as those of the configurations described in the embodiments, or configurations capable of achieving the same objectives as those of the configurations described in the embodiments. The invention further includes configurations obtained by adding known art to the configurations described in the embodiments. 
     As described above, some embodiments of the invention have been described in detail, but a person skilled in the art will readily appreciate that various modifications can be made from the embodiments without materially departing from the novel teachings and effects of the invention. Accordingly, all such modifications are assumed to be included in the scope of the invention.