Evaluation method and analyzer

Abstract

To provide an evaluation method capable of evaluating the density of a sample.SOLUTION: An analysis method according to the present invention includes a step of acquiring a backscattered electron spectrum of a sample, a step of performing waveform separation on an elastic scattering peak of the backscattered electron spectrum to separate the elastic scattering peak into a plurality of peaks and acquiring information on a position of each peak, a width of each peak, and an intensity of each peak, a step of specifying each element constituting the sample from the position of each peak and the width of each peak, and a step of obtaining a density of each element constituting the sample from the intensity of each peak.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an evaluation method and an analysis device. [Background technology]

[0002] One material evaluation technique that uses backscattered electrons is backscattered electron imaging. A backscattered electron image is obtained by scanning a sample with an electron beam, detecting electrons reflected by the sample, and displaying the intensity distribution of the detected electrons. For example, Patent Document 1 discloses a scanning electron microscope equipped with a backscattered electron detector for acquiring backscattered electron images. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-123990 Summary of the Invention [Problem to be solved by the invention]

[0004] Backscattered electron imaging allows for easy evaluation of the composition of a sample using backscattered electrons. However, backscattered electron imaging does not allow for evaluation of the density of a sample, and a method for evaluating the density of a sample is desired. [Means for solving the problem]

[0005] One aspect of the evaluation method according to the present invention is to obtaining a backscattered electron spectrum of the sample; a step of separating the elastic scattering peak of the backscattered electron spectrum into a plurality of peaks by waveform separation, and acquiring information on the position, width, and intensity of each peak; identifying each element constituting the sample from the position and width of each peak; determining the density of each element constituting the sample from the intensity of each peak; Includes.

[0006] In this evaluation method, the density of the sample can be evaluated from the backscattered electron spectrum.

[0007] One aspect of the evaluation method according to the present invention is to obtaining a backscattered electron spectrum of the sample; a step of separating the elastic scattering peak of the backscattered electron spectrum into a plurality of peaks by waveform separation, and acquiring information on the position, width, and intensity of each peak; identifying each element constituting the sample from the position and width of each peak; Includes.

[0008] In such an evaluation method, each element constituting the sample can be identified from the backscattered electron spectrum.

[0009] One aspect of the analysis device according to the present invention is an electron optical system that irradiates an electron beam onto a sample; an electron spectroscopic analyzer that detects reflected electrons emitted from the sample by spectroscopy; a control unit that controls the electron optical system; Including, The control unit obtaining a backscattered electron spectrum of the sample; A process of separating the elastic scattering peak of the backscattered electron spectrum into a plurality of peaks by waveform separation, and acquiring information on the position, width, and intensity of each peak; a process of identifying each element constituting the sample from the position and width of each peak; A process of determining the density of each element constituting the sample from the intensity of each peak; Do the following.

[0010] Such an analyzer can evaluate the density of a sample from the backscattered electron spectrum.

[0011] One aspect of the analysis device according to the present invention is an electron optical system that irradiates an electron beam onto a sample; an electron spectroscopic analyzer that detects reflected electrons emitted from the sample by spectroscopy; a control unit that controls the electron optical system; Including, The control unit obtaining a backscattered electron spectrum of the sample; A process of separating the elastic scattering peak of the backscattered electron spectrum into a plurality of peaks by waveform separation, and acquiring information on the position, width, and intensity of each peak; a process of identifying each element constituting the sample from the position and width of each peak; Do the following.

[0012] Such an analyzer can identify each element that constitutes a sample from the backscattered electron spectrum. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing the configuration of an analysis device according to a first embodiment. [Figure 2] 10 is a flowchart showing an example of a method for evaluating the density of a sample. [Figure 3] Correlation diagram showing the relationship between atomic number and the position of the elastic scattering peak. [Figure 4] Correlation diagram showing the relationship between atomic number and the width of the elastic scattering peak. [Figure 5] Correlation diagram showing the relationship between atomic number and elastic scattering peak intensity. [Figure 6] A correlation diagram showing the relationship between atomic number and density. [Figure 7] 1 is a graph showing an example of an approximation curve showing the relationship between atomic number and the position of an elastic scattering peak. [Figure 8] 1 is a graph showing an example of an approximation curve showing the relationship between atomic number and the width of an elastic scattering peak. [Figure 9] 1 is a graph showing an example of the results of waveform separation of elastic scattering peaks of an analysis sample. [Figure 10] 10 is a flowchart showing an example of a density evaluation process by a control unit. [Figure 11]FIG. 1 is a diagram for explaining a spectral image. DETAILED DESCRIPTION OF THE INVENTION

[0014] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. Note that the embodiments described below do not unduly limit the content of the present invention as defined in the claims. Furthermore, not all of the configurations described below are necessarily essential components of the present invention.

[0015] 1. First embodiment 1.1. Analyzer First, an analysis device according to a first embodiment will be described with reference to the drawings. Fig. 1 is a diagram showing an example of the configuration of an analysis device 100 according to the first embodiment.

[0016] 1, the analytical device 100 includes an electron optical system 20, a sample stage 30, an electron spectroscopic analyzer 40, and a control unit 50. The analytical device 100 is, for example, a scanning electron microscope equipped with the electron spectroscopic analyzer 40.

[0017] The electron optical system 20 is an optical system for irradiating an electron beam onto a sample. The electron optical system 20 can irradiate an electron beam onto a single point on the sample. Furthermore, the electron optical system 20 can focus the electron beam to form an electron probe, and scan the sample S with the electron probe. The electron optical system 20 includes an electron source 21, a focusing lens 22, a deflector 24, and an objective lens 26.

[0018] The electron source 21 emits an electron beam. The electron source 21 is, for example, an electron gun that accelerates electrons emitted from a cathode by an acceleration voltage applied between the cathode and an anode, and emits an electron beam.

[0019] The focusing lens 22 and the objective lens 26 focus the electron beam emitted from the electron source 21 to form an electron probe. The deflector 24 two-dimensionally deflects the electron beam focused by the focusing lens 22 and the objective lens 26. By deflecting the electron beam with the deflector 24, the sample S can be scanned with the electron probe.

[0020] The sample stage 30 holds the sample S. The sample stage 30 is equipped with, for example, a horizontal movement mechanism that moves the sample S in the horizontal direction, a height movement mechanism that moves the sample S in the height direction, and a tilt mechanism that tilts the sample S. The sample stage 30 allows the sample S to be positioned.

[0021] The electron spectrometer analyzer 40 disperses and detects the energy of electrons emitted from the sample S when irradiated with an electron beam. The electron spectrometer analyzer 40 is, for example, an electrostatic hemispherical analyzer. The electrostatic hemispherical analyzer has an inner hemispherical electrode, an outer hemispherical electrode, and a detector, and by changing the voltage between the inner and outer hemispherical electrodes, electrons within an energy range corresponding to the applied voltage can be made to enter the detector. An energy spectrum can be obtained by counting the electrons detected by the electron spectrometer analyzer 40 for each energy.

[0022] The electron spectroscopic analyzer 40 is not limited to an electrostatic hemispherical analyzer as long as it can obtain an energy spectrum by dispersing the energy of electrons emitted from the sample S. For example, the electron spectroscopic analyzer 40 may be a cylindrical mirror analyzer (CMA) or a plane mirror analyzer (PMA).

[0023] The control unit 50 (computer) controls each part of the analytical device 100, such as the electron optical system 20, the sample stage 30, and the electron spectrometer 40. The control unit 50 includes a processor such as a CPU (Central Processing Unit) or a DSP (Digital Signal Processor), and a storage unit including a RAM (Random Access Memory) and a ROM (Read Only Memory). The control unit 50 performs various calculation processes and various control processes by having the processor execute programs stored in the storage unit.

[0024] Evaluation Method 1.2.1. Principle In the evaluation method according to the first embodiment, the backscattered electron spectrum is acquired using the analysis device 100, and the elements constituting the sample S can be qualitatively evaluated using the acquired backscattered electron spectrum. Furthermore, in the evaluation method according to the first embodiment, the density of the elements constituting the sample S can be relatively evaluated using the acquired backscattered electron spectrum.

[0025] Backscattered electrons are electrons that are incident on a sample and are reflected off the rear surface, escaping from the sample surface. The elastic scattering peak in a backscattered electron spectrum is a peak that represents the intensity of elastically scattered electrons. Elastic scattering is a phenomenon in which electrons incident on a sample collide with atoms and are scattered without losing their energy. The elastic scattering peak is a peak (zero-loss peak) that represents the intensity of electrons that are scattered without losing this energy.

[0026] Here, when the incident electrons collide with the sample atoms and the sample atoms are subjected to an impulse, the incident electrons lose energy, and the position (energy position) and width (energy width) of the elastic scattering peak change depending on the mass of the atoms constituting the sample. Utilizing this, the evaluation method in the first embodiment identifies the type of each element constituting the sample from the position and width of the elastic scattering peak.

[0027] Furthermore, the intensity of the elastic scattering peak is affected not only by the atomic number (or average atomic number) but also by the density of the elements that make up the sample. Taking advantage of this, the evaluation method in the first embodiment evaluates the density of each element that makes up the sample from the intensity of the elastic scattering peak.

[0028] 1.2.2. Evaluation method flow FIG. 2 is a flowchart showing an example of a method for evaluating the density of a sample in the first embodiment.

[0029] First, information on the relationship between the atomic number and the position of the elastic scattering peak is obtained (step S100).

[0030] Figure 3 is a correlation diagram showing the relationship between atomic number and the position of the elastic scattering peak. As mentioned above, the position of the elastic scattering peak in the backscattered electron spectrum (hereinafter simply referred to as "position") shifts depending on the mass of the atoms that make up the sample. A method for creating the correlation diagram shown in Figure 3 will be described below.

[0031] First, a backscattered electron spectrum is obtained from a sample with a known atomic number. The sample is irradiated with an electron beam by the electron optical system 20, and the backscattered electrons among the electrons emitted from the sample are separated by the electron spectroscopic analyzer 40 to obtain a backscattered electron spectrum.

[0032] Next, information on the position of the elastic scattering peak is obtained from the backscattered electron spectrum of a sample with a known atomic number. The position of the elastic scattering peak can be determined by fitting the elastic scattering peak using a Gaussian function or a Gauss-Lorentzian function.

[0033] The acquisition of the backscattered electron spectrum and the information on the position of the elastic scattering peak are repeated by changing the type of element that makes up the sample. This allows the creation of a correlation diagram showing the relationship between atomic number and position, as shown in Figure 3. In the correlation diagram shown in Figure 3, the position of the elastic scattering peak of gold (Au), which has atomic number 79, is used as the reference. In other words, the position of atomic number 79 is set to zero.

[0034] Next, information on the relationship between the atomic number and the width of the elastic scattering peak is obtained (step S102).

[0035] Figure 4 is a correlation diagram showing the relationship between atomic number and the width (full width at half maximum) of the elastic scattering peak. The width of the elastic scattering peak (hereinafter simply referred to as "width") varies depending on the mass of the atoms that make up the sample. Here, the width of the elastic scattering peak is expressed as the full width at half maximum.

[0036] The method for creating the correlation diagram shown in Figure 4 will be explained below. The differences from the example of creating a correlation diagram showing the relationship between numbers and positions will be explained, and explanation of similarities will be omitted.

[0037] First, a backscattered electron spectrum is obtained for a sample with a known atomic number. Next, information on the width of the elastic scattering peak is obtained from the backscattered electron spectrum for the sample with a known atomic number. The width of the elastic scattering peak can be determined by fitting the elastic scattering peak using a Gaussian function or Gauss-Lorentzian function. The process of obtaining a backscattered electron spectrum and information on the width of the elastic scattering peak is repeated for different elements that make up the sample. This allows the creation of a correlation diagram showing the relationship between atomic number and width, as shown in Figure 4. In the correlation diagram shown in Figure 4, the width of the elastic scattering peak of gold (Au), which has atomic number 79, is used as the reference. In other words, the width of the atomic number 79 is set to 1.

[0038] Note that the backscattered electron spectrum of a sample with a known atomic number may be the backscattered electron spectrum of a known sample used to obtain information on the relationship between atomic number and position in step S100.

[0039] Next, information on the relationship between the atomic number and the intensity of the elastic scattering peak is obtained (step S104).

[0040] FIG. 5 is a correlation diagram showing the relationship between atomic number and the intensity of the elastic scattering peak. The intensity of the elastic scattering peak (hereinafter simply referred to as "intensity") varies depending on the mass of the atoms constituting the sample. A method for creating the correlation diagram shown in FIG. 5 will be described below. Note that differences from the example of creating a correlation diagram showing the relationship between atomic number and position shown in FIG. 3 described above will be described, and similar points will not be described again.

[0041] First, a backscattered electron spectrum is obtained for a sample with a known atomic number. Next, information on the intensity of the elastic scattering peak is obtained from the backscattered electron spectrum of the sample with a known atomic number. The acquisition of the backscattered electron spectrum and the information on the intensity of the elastic scattering peak are repeated for different types of elements that make up the sample. This makes it possible to create a correlation diagram showing the relationship between atomic number and intensity, as shown in Figure 5.

[0042] Note that the backscattered electron spectrum of a sample with a known atomic number may be the backscattered electron spectrum of a known sample used to obtain information on the relationship between atomic number and position in step S100.

[0043] Next, information on the relationship between atomic number and element density (hereinafter simply referred to as "density") is obtained (step S105). Figure 6 is a correlation diagram showing the relationship between atomic number and density. The relationship between atomic number and density can be obtained from literature values.

[0044] Next, information on the relationship between strength and density is obtained (step S106).

[0045] The correlation diagram shown in FIG. 5 is expressed as a mathematical formula using linear approximation to obtain a function showing the relationship between atomic number and intensity. Similarly, the correlation diagram shown in FIG. 6 is expressed as a mathematical formula using linear approximation to obtain a function showing the relationship between atomic number and density. From these two functions, a relational equation between intensity and density can be obtained. Note that although linear approximation is used here, the method for obtaining these two functions is not particularly limited.

[0046] In the examples shown in FIGS. 5 and 6, the relation between density D and intensity I of the elastic scattering peak is expressed as the following equation (1).

[0047] D = 7.2 × 10 -5 I···(1)

[0048] Next, a reference spectrum is obtained (step S108).

[0049] The reference spectrum is the backscattered electron spectrum of a standard sample composed of elements with known atomic numbers. A heavy element with a relatively large atomic number is used as the standard sample. For example, a pure element with an atomic number greater than 10 is used as the standard sample. Here, gold (Au) is used as the standard sample.

[0050] Next, information on the position and width of the elastic scattering peak of the reference spectrum is obtained (step S110).

[0051] The position and width of the elastic scattering peak are determined by fitting the reference spectrum using a Gaussian function or Gauss-Lorentzian function. The width of the elastic scattering peak is expressed, for example, as the full width at half maximum. Note that there are no particular limitations on the fitting method, as long as it can provide information on the position and width of the elastic scattering peak.

[0052] Next, the relationship between the atomic number and the position is corrected using the position of the elastic scattering peak of the reference spectrum (step S112).

[0053] The relationship between atomic number and position shown in Figure 3 is corrected using information on the position of the elastic scattering peak of the reference spectrum acquired in step S110. Because the atomic number of the standard sample is known, the correlation diagram shown in Figure 3 can be corrected using the position of the elastic scattering peak of the standard sample. When gold (Au) is used as the standard sample, the correlation diagram shown in Figure 3 is corrected so that the position of the peak of gold (atomic number 79) in the correlation diagram shown in Figure 3 corresponds to the position of the peak acquired in step S110.

[0054] Here, the position of the elastic scattering peak fluctuates due to fluctuations in the characteristics of the electron source 21 caused by external factors such as the temperature during measurement. By correcting the correlation diagram shown in Fig. 3 using the position of the elastic scattering peak of the standard sample (gold), the influence of fluctuations in the characteristics of the electron source 21 caused by external factors can be reduced.

[0055] Next, the relationship between the atomic number and the width is corrected using the width of the elastic scattering peak of the reference spectrum (step S114).

[0056] The relationship between the atomic number and the width is corrected using information about the width of the elastic scattering peak of the reference spectrum acquired in step S110. Because the atomic number of the standard sample is known, the width of the elastic scattering peak of the standard sample can be used to correct the correlation diagram shown in FIG. 4. When gold (Au) is used as the standard sample, the correlation diagram shown in FIG. 4 is corrected so that the width of gold (atomic number 79) corresponds to the width of the peak acquired in step S110. This reduces the influence of fluctuations in the characteristics of the electron source 21 due to external factors.

[0057] Next, information on the relationship between the position of the elastic scattering peak and the width of the elastic scattering peak is obtained (step S116).

[0058] Here, a function showing the relationship between position and width is calculated as the information on the relationship between position and width. The function showing the relationship between position and width can be generated from information on the relationship between atomic number and position and information on the relationship between atomic number and width.

[0059] Fig. 7 is a graph showing an example of an approximation curve showing the relationship between atomic number and position. Fig. 8 is a graph showing an example of an approximation curve showing the relationship between atomic number and width. In Fig. 7 and Fig. 8, actual measurements are shown as dots, and the approximation curve is shown as a solid line.

[0060] As shown in Figure 7, an approximate curve is drawn on the correlation diagram corrected with the reference spectrum, and a function showing the relationship between atomic number and position is obtained. Similarly, as shown in Figure 8, an approximate curve is drawn on the correlation diagram corrected with the reference spectrum, and a function showing the relationship between atomic number and width is obtained. A function showing the relationship between position and width is calculated from the two functions obtained.

[0061] In the examples shown in FIGS. 7 and 8, a function inversely proportional to the square root of the atomic number is used as the function representing the approximation curve, but other functions may also be used.

[0062] Furthermore, although the case where a function showing the relationship between position and width is generated as the information on the relationship between position and width has been described, actual measured values ​​may also be used as the information on the relationship between position and width. For example, using the correlation diagrams shown in Figure 3 and Figure 4, the actual measured values ​​of the positions of elastic scattering peaks and the actual measured values ​​of the widths of elastic scattering peaks may be associated one-to-one to obtain the information on the relationship between position and width.

[0063] Next, a backscattered electron spectrum of the sample to be analyzed is obtained (step S118).

[0064] The backscattered electron spectrum of the sample to be analyzed is obtained, similarly to the reference spectrum, by irradiating the sample with an electron beam using the electron optical system 20 and then separating the backscattered electrons among the electrons emitted from the sample using the electron spectrometer 40.

[0065] Next, the elastic scattering peak of the backscattered electron spectrum of the sample to be analyzed is separated into a plurality of peaks by waveform separation, and information on the position, width, and intensity of each peak is obtained (step S120).

[0066] The elastic scattering peak is the sum of the elastic scattering peaks of the multiple elements that make up the sample to be analyzed. Therefore, waveform separation is performed on the elastic scattering peak to calculate the abundance ratio of each element, the peak position of each element, and the peak width (full width at half maximum) of each element. The waveform separation of the elastic scattering peak is performed using the relationship between position and width obtained in step S116 as a constraint. In other words, the elastic scattering peak is waveform separated so as to satisfy the relationship between position and width obtained in step S116. As the relationship between position and width, a function representing the relationship may be used, or an actual measured value may be used.

[0067] Figure 9 is a graph showing an example of the results of waveform separation of the elastic scattering peak of an analytical sample. In the example shown in Figure 9, the elastic scattering peak is a composite of two peaks, so it was separated into component 1 and component 2 by waveform separation. This makes it possible to obtain information on the peak position, peak width, and peak intensity for each of component 1 and component 2. In addition, information on the abundance ratio (proportion) of component 1 and component 2 can be obtained from the intensity ratio of component 1 to component 2.

[0068] By performing waveform separation of the elastic scattering peaks using the relationship between position and width obtained in step S116 as a constraint, the position and width of the peak of component 1 shown in Fig. 9 satisfy the relationship between position and width obtained in step S116. Similarly, the position and width of the peak of component 2 satisfy the relationship between position and width obtained in step S116.

[0069] Next, the elastic scattering peaks of the sample to be analyzed are subjected to waveform separation, and the elements constituting the sample to be analyzed are identified from the position and width of each peak (step S122).

[0070] Based on the relationship between atomic number and position, or the relationship between atomic number and width, each element constituting the sample to be analyzed is identified from the position and width of each peak. For example, the atomic number is obtained from the position of each peak using a scatter diagram (actual measured values) showing the relationship between atomic number and position shown in Figure 3, and the element is identified. Also, for example, the scatter diagram (actual measured values) showing the relationship between atomic number and width shown in Figure 4 can be used to determine the atomic number from the position of each peak. The atomic number may be determined from the width of each peak using a function representing the atomic number and position, and the element may be identified. Note that each element constituting the sample to be analyzed may be identified from a function representing the relationship between atomic number and position, or from a function representing the relationship between atomic number and width.

[0071] In the example shown in Figure 9, as a result of waveform separation of the elastic scattering peak, it can be estimated that the sample to be analyzed is composed of two elements, Si and C. Furthermore, as a result of waveform separation of the elastic scattering peak, it can be estimated that the abundance ratio of Si to C is 1:1.

[0072] Next, the density of each element constituting the sample is determined from the intensity of each peak obtained by waveform separation of the elastic scattering peak of the sample to be analyzed (step S124).

[0073] The density of each element is calculated from the intensity of each peak based on the information on the relationship between density and intensity obtained in step S106. For example, the density of each element can be calculated by substituting the intensity of each peak obtained in step S120 into the relationship between density and intensity shown in equation (1) obtained in step S106. By comparing the calculated density with the theoretical density of the element, the relative density of the element constituting the sample to the theoretical density can be determined.

[0074] Through the above steps, the density of each element that constitutes the sample to be analyzed can be evaluated.

[0075] Here, the elastic scattering peak is a peak resulting from the phenomenon in which incident electrons change direction (scatter) without losing energy when colliding with sample atoms. Therefore, it is preferable that the backscattered electron spectrum used in step S100, the backscattered electron spectrum used in step S102, the backscattered electron spectrum used in step S104, the backscattered electron spectrum (reference spectrum) used in step S106, and the backscattered electron spectrum of the analysis sample used in step S118 are measured at the same accelerating voltage and the same tilt angle.

[0076] The elastic scattering peak is a peak resulting from the phenomenon in which incident electrons change direction (scatter) without losing energy when colliding with sample atoms. Therefore, the ratio of the intensity of the elastic scattering peak to the intensity of the incident electrons (the backscattered electron coefficient) changes when the accelerating voltage and the tilt angle of the sample change. That is, when the accelerating voltage and the tilt angle of the sample change, the position, shape, and intensity of the elastic scattering peak change. Therefore, it is preferable that the backscattered electron spectra used in the above steps S100, S102, S104, S106, and S118 are measured at the same accelerating voltage and the same tilt angle. Note that correctable parameters, such as the irradiation current, which is the amount of electron beam current irradiated onto the sample, may be different in the measurements of the backscattered electron spectra used in the above steps.

[0077] Processing In the analytical device 100, the control unit 50 performs processing to evaluate the density of each element constituting the sample to be analyzed. The memory unit of the control unit 50 pre-stores information on the relationship between atomic number and position shown in Fig. 3, information on the relationship between atomic number and width shown in Fig. 4, and information on the relationship between intensity and density.

[0078] 10 is a flowchart showing an example of the density evaluation process of the control unit 50. Note that a description of the same points as in the example of the evaluation method shown in FIG.

[0079] When the control unit 50 receives an instruction from the user to start the density evaluation process, it measures the standard sample and obtains a reference spectrum (step S200). The control unit 50 controls the electron optical system 20 so that the standard sample is irradiated with an electron beam. As a result, a backscattered electron spectrum is generated in the electron spectrometer analyzer 40. The backscattered electron spectrum generated in the electron spectrometer analyzer 40 is sent to the control unit 50. As a result, the control unit 50 obtains the reference spectrum. You can obtain the rule.

[0080] The control unit 50 performs fitting using a Gaussian function or the like on the acquired reference spectrum to determine the position and width of the elastic scattering peak, and acquires information on the position and width of the elastic scattering peak (step S202).

[0081] Next, the control unit 50 corrects the relationship between the atomic number and the position stored in the storage unit with the position of the elastic scattering peak of the reference spectrum (step S204). Next, the control unit 50 corrects the relationship between the atomic number and the width stored in the storage unit with the width of the elastic scattering peak of the reference spectrum (step S206).

[0082] The control unit 50 obtains the relationship between the position and width of the elastic scattering peak from the relationship between the corrected atomic number and the position and the relationship between the corrected atomic number and the width (step S208).

[0083] Next, the control unit 50 acquires the backscattered electron spectrum of the sample to be analyzed (step S210). The backscattered electron spectrum of the sample to be analyzed can be acquired by a process similar to that of acquiring the reference spectrum in step S200. The control unit 50 sets the conditions of the acceleration voltage and the tilt angle of the sample in measuring the backscattered electron spectrum of the sample to the same conditions as those in measuring the backscattered electron spectrum of the standard sample in step S200.

[0084] As shown in Fig. 9, the control unit 50 performs waveform separation on the elastic scattering peaks of the backscattered electron spectrum of the sample to be analyzed to separate them into multiple peaks, and acquires information on the position, width, and intensity of each peak (step S212). The control unit 50 performs waveform separation on the elastic scattering peaks of the sample to be analyzed, using the relationship between width and position as a constraint. The control unit 50 calculates the peak position, peak width, and peak intensity for each of the multiple separated peaks.

[0085] The control unit 50 identifies each element constituting the sample to be analyzed from the position and width of each peak obtained by waveform separation (step S214). The control unit 50 determines the atomic number from the position of each peak using, for example, a scatter diagram showing the relationship between atomic number and position as shown in FIG. 3, and identifies the element. The control unit 50 may also determine the atomic number from the width of each peak using a scatter diagram showing the relationship between atomic number and width as shown in FIG. 4, and identify the element. Furthermore, the control unit 50 determines the abundance ratio of each element from the results of waveform separation.

[0086] The control unit 50 determines the density of each element constituting the sample to be analyzed from the intensity of each peak obtained by waveform separation (step S216). The control unit 50 determines the density of each element from the intensity of each peak using information on the relationship between atomic number and element density stored in the memory unit. For example, the control unit 50 determines the density of each element by substituting the intensity of each peak into the relationship between density and intensity shown in the above-mentioned equation (1), which is stored in the memory unit.

[0087] After performing the process S216 for determining the density, the control unit 50 ends the density evaluation process.

[0088] Effects The evaluation method of the first embodiment includes the steps of acquiring a backscattered electron spectrum of a sample, separating elastic scattering peaks of the backscattered electron spectrum into multiple peaks by waveform separation, and acquiring information on the position, width, and intensity of each peak, identifying each element constituting the sample from the position and width of each peak, and determining the density of each element constituting the sample from the intensity of each peak. Therefore, the evaluation method of the first embodiment can identify each element constituting the sample from the backscattered electron spectrum. Furthermore, the evaluation method of the first embodiment can evaluate the density of the sample.

[0089] For example, the composition of a sample can also be evaluated using a backscattered electron image. A backscattered electron image is an image that shows the distribution of backscattered electron intensity, which is obtained by scanning the sample with an electron beam and detecting backscattered electrons emitted from the sample. However, the intensity of backscattered electrons is affected by the average atomic number, crystal orientation, and density, making it difficult to accurately evaluate the composition of the sample.

[0090] Furthermore, for example, in energy loss spectroscopy (REELS) using backscattered electrons, inelastically scattered electrons that lose a portion of their energy through interaction with a sample are dispersed to obtain an energy loss spectrum, and the composition of the sample is evaluated from the loss peaks in the spectrum. However, the loss peaks in the energy loss spectrum have only a small intensity. In contrast, the elastic scattering peak (zero loss peak) of the backscattered electron spectrum obtained by dispersing elastically scattered electrons has a larger intensity than the loss peak. Therefore, the evaluation method according to the first embodiment can more accurately evaluate the composition and density of the sample.

[0091] The evaluation method of the first embodiment includes a step of acquiring information on the relationship between the position and width of the elastic scattering peak, and the relationship between the position and width of the elastic scattering peak is used as a constraint in the waveform separation step. Therefore, the evaluation method of the first embodiment can accurately separate the elastic scattering peak of the sample, accurately identify each element constituting the sample to be analyzed, and accurately evaluate the density of the sample.

[0092] The evaluation method of the first embodiment includes the steps of acquiring a reference spectrum, which is a backscattered electron spectrum of a sample with a known atomic number; determining the position and width of the elastic scattering peak of the reference spectrum; correcting the relationship between the atomic number and the position of the elastic scattering peak using the position of the elastic scattering peak of the reference spectrum; and correcting the relationship between the atomic number and the width of the elastic scattering peak using the width of the elastic scattering peak of the reference spectrum. Furthermore, in the step of acquiring information on the relationship between the position and width of the elastic scattering peak, the relationship between the position and width of the elastic scattering peak is determined from the relationship between the corrected atomic number and the position of the elastic scattering peak and the relationship between the corrected atomic number and the width of the elastic scattering peak. Therefore, the evaluation method of the first embodiment can reduce the influence of the characteristics of the electron source 21 on the position and width of the elastic scattering peak, accurately identify each element constituting the sample, and more accurately evaluate the density of the sample.

[0093] The analytical instrument 100 includes an electron optical system 20 that irradiates an electron beam onto a sample, an electron spectrometer 40 that detects backscattered electrons emitted from the sample by spectroscopy, and a control unit 50 that controls the electron optical system 20. The control unit 50 also performs the following operations: acquiring a backscattered electron spectrum of the sample; waveform-separating the elastic scattering peaks of the backscattered electron spectrum into multiple peaks and acquiring information on the position, width, and intensity of each peak; identifying each element constituting the sample from the position and width of each peak; and determining the density of each element constituting the sample from the intensity of each peak. Therefore, the analytical instrument 100 can identify each element constituting the sample from the backscattered electron spectrum. Furthermore, the analytical instrument 100 can evaluate the density of the sample.

[0094] 1.5. Variations 1.5.1. First variant In the above-described embodiment, the relationship between atomic number and position and the relationship between atomic number and width are corrected using the reference spectrum, but the relationship between atomic number and position and the relationship between atomic number and width do not have to be corrected. That is, it is not necessary to perform step S108 of acquiring the reference spectrum shown in FIG. 2, step S110 of acquiring information on the position and width of the elastic scattering peak of the reference spectrum, step S112 of correcting the relationship between atomic number and position, and step S114 of correcting the relationship between atomic number and width. Similarly, the control unit 50 may perform step S20 of acquiring the reference spectrum shown in FIG. 10. 0, it is not necessary to perform the process S202 for acquiring information on the position and width of the elastic scattering peak of the reference spectrum, the process S204 for correcting the relationship between the atomic number and the position, and the process S206 for correcting the relationship between the atomic number and the width.

[0095] 1.5.2. Second Variant In the above-described embodiment, the steps of the evaluation method are performed in the order shown in the flowchart of Fig. 2, but the order in which the steps are performed can be changed as appropriate. Similarly, the order of the processes shown in Fig. 10 can be changed as appropriate.

[0096] 1.5.3. Third Variant In the above-described embodiment, in step S124 for determining density, the density of each element is calculated by substituting the intensity of each peak obtained in step S120 into the relational expression between the density and the intensity of the elastic scattering peak obtained in step S106. Alternatively, for example, the density may be determined by comparing the intensity of the elastic scattering peak estimated from the element identified in step S122 with the intensity of the elastic scattering peak of the analysis target sample obtained in step S120. For example, the density may be determined based on the difference between the intensity of the elastic scattering peak estimated from the element identified in step S122 and the intensity of the elastic scattering peak of the analysis target sample obtained in step S120. Information on the intensity of the elastic scattering peak estimated from the element identified in step S122 may be obtained from the measured values ​​of the scatter diagram shown in FIG. 5.

[0097] 2. Second embodiment 2.1. Analyzer Next, an analysis device according to a second embodiment will be described. The configuration of the analysis device according to the second embodiment is similar to the configuration of the analysis device 100 according to the first embodiment shown in Fig. 1, and therefore a description thereof will be omitted.

[0098] Evaluation Method In the second embodiment, a sample to be analyzed is scanned two-dimensionally with an electron beam, a backscattered electron spectrum is collected at each measurement point to obtain a spectral image (spectral map), and density is evaluated at each measurement point of the spectral image, thereby visualizing the density distribution of the sample to be analyzed.

[0099] FIG. 11 is a diagram for explaining a spectral image. A spectral image is data that associates the position of a measurement point on a sample with a spectrum. A spectral image has multiple pixels P, and the coordinates (X, Y) of the pixel P correspond to the position of the measurement point on the sample. The pixel P stores the backscattered electron spectrum collected at the measurement point on the sample that corresponds to the coordinates (X, Y) of the pixel P.

[0100] The backscattered electron spectrum stored in each pixel P of the spectral image is subjected to the evaluation method shown in FIG. 2, and each element constituting the sample is identified for each measurement point, i.e., for each pixel P, and the density of each element is calculated.

[0101] 2, in step S118 of acquiring a backscattered electron spectrum of the sample to be analyzed, the sample to be analyzed is scanned two-dimensionally with an electron beam, and a backscattered electron spectrum is acquired for each measurement point. This makes it possible to acquire a spectral image in which the positions of the measurement points on the sample are associated with the backscattered electron spectrum. In the spectral image, the backscattered electron spectrum is stored in the pixel P corresponding to the position of the measurement point.

[0102] In the step S120 of waveform separation of the backscattered electron spectrum of the sample to be analyzed, the elastic scattering peak of the backscattered electron spectrum is waveform separated for each measurement point, i.e., for each pixel P. As a result, information on the position, width, and intensity of each peak can be obtained for each pixel P.

[0103] In step S122 of identifying each element constituting the analysis sample, each element constituting the analysis sample is identified from the position and width of each peak for each measurement point, i.e., for each pixel P. This makes it possible to identify each element constituting the analysis sample for each pixel P.

[0104] In step S124 of determining the density of each element constituting the analysis sample, the density of each element constituting the analysis sample is determined for each measurement point, ie, for each pixel P, from the intensity of the elastic scattering peak of the backscattered electron spectrum.

[0105] In this way, by determining the density for each pixel P of the spectral image, the in-plane density distribution of the sample to be analyzed can be visualized.

[0106] Processing In the second embodiment, the control unit 50 performs the density evaluation process shown in Fig. 10 on the backscattered electron spectrum stored in each pixel of the spectral image, identifies each element constituting the sample for each pixel P, i.e., for each measurement point, and calculates the density of each element. This visualizes the in-plane density distribution of the sample to be analyzed.

[0107] Specifically, in step S210 for acquiring the backscattered electron spectrum of the sample to be analyzed, the control unit 50 controls the electron optical system 20 to two-dimensionally scan the sample to be analyzed with an electron beam, and acquires the backscattered electron spectrum for each measurement point from the electron spectrometer analyzer 40. This allows the control unit 50 to acquire a spectral image.

[0108] In step S212 of performing waveform separation on the backscattered electron spectrum of the analysis sample, the control unit 50 performs waveform separation on the elastic scattering peaks of the backscattered electron spectrum for each measurement point, i.e., for each pixel P. As a result, the control unit 50 obtains information on the position, width, and intensity of each peak for each pixel P.

[0109] In step S214 of identifying each element constituting the sample to be analyzed, the control unit 50 identifies each element constituting the sample to be analyzed for each measurement point, i.e., for each pixel P, from the position and width of each peak.

[0110] In step S216 of determining the density of each element constituting the sample to be analyzed, the control unit 50 determines the density of each element constituting the sample to be analyzed for each measurement point, i.e., for each pixel P, from the intensity of the elastic scattering peak of the backscattered electron spectrum.

[0111] Through the above processing, the control unit 50 generates an image showing the in-plane distribution of density of the sample to be analyzed.

[0112] Effects In the evaluation method of the second embodiment, in the step of acquiring a backscattered electron spectrum, a spectral image in which the positions of measurement points on the sample and the backscattered electron spectrum are associated is acquired, in the step of waveform separation, elastic scattering peaks of the backscattered electron spectrum are waveform separated for each measurement point, in the step of identifying each element constituting the sample, each element is identified for each measurement point, and in the step of determining the density of each element constituting the sample, the density of each element is determined for each measurement point. Therefore, the evaluation method of the second embodiment can generate an image showing the in-plane distribution of density of the sample.

[0113] Therefore, with the evaluation method of the second embodiment, for example, the hydrogen distribution of a sample can be evaluated indirectly from an image showing the in-plane distribution of the density of the sample. Portions of a sample that contain hydrogen atoms have a lower density than portions that do not contain hydrogen atoms. Therefore, the hydrogen distribution can be evaluated indirectly from an image showing the in-plane distribution of the density of the sample. For example, in a hydrogen storage alloy, the density of portions that have absorbed hydrogen is lower. Therefore, by generating an image showing the in-plane distribution of density using the evaluation method of the second embodiment, it is possible to visualize portions of the hydrogen storage alloy that have absorbed a large amount of hydrogen and portions that have absorbed a small amount of hydrogen.

[0114] The above-described embodiment and modifications are merely examples, and the present invention is not limited to these. For example, the embodiments and modifications can be combined as appropriate.

[0115] The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the present invention includes configurations that are substantially identical to the configurations described in the embodiments. A substantially identical configuration means, for example, a configuration with the same function, method, and result, or a configuration with the same purpose and effect. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that achieve the same effects or purposes as the configurations described in the embodiments. The present invention also includes configurations in which publicly known technology is added to the configurations described in the embodiments. [Explanation of symbols]

[0116] 20...electron optical system, 21...electron source, 22...focusing lens, 24...deflector, 25...scanning deflector, 26...objective lens, 30...sample stage, 40...electron spectroscopic analyzer, 50...controller, 100...analytical device

Claims

1. obtaining a backscattered electron spectrum of the sample; a step of separating the elastic scattering peak of the backscattered electron spectrum into a plurality of peaks by waveform separation, and acquiring information on the position, width, and intensity of each peak; identifying each element constituting the sample from the position and width of each peak; determining the density of each element constituting the sample from the intensity of each peak; Evaluation methods, including:

2. In claim 1, In the step of acquiring the backscattered electron spectrum, a spectral image is acquired in which the position of the measurement point on the sample and the backscattered electron spectrum are associated with each other; In the waveform separation step, an elastic scattering peak of the backscattered electron spectrum is subjected to waveform separation for each of the measurement points; In the step of identifying each element constituting the sample, each element is identified for each of the measurement points, In the step of determining the density of each element constituting the sample, the density of each element is determined for each of the measurement points.

3. In claim 1, acquiring information on the relationship between the position of the elastic scattering peak and the width of the elastic scattering peak; An evaluation method, wherein the waveform separation step sets a constraint on the relationship between the position of the elastic scattering peak and the width of the elastic scattering peak.

4. In claim 3, acquiring a reference spectrum, which is a backscattered electron spectrum of a sample having a known atomic number; determining the position and width of the elastic scattering peak of the reference spectrum; correcting the relationship between the atomic number and the position of the elastic scattering peak with the position of the elastic scattering peak of the reference spectrum; correcting the relationship between the atomic number and the width of the elastic scattering peak with the width of the elastic scattering peak of the reference spectrum; Including, In the step of acquiring information on the relationship between the position of the elastic scattering peak and the width of the elastic scattering peak, the relationship between the position of the elastic scattering peak and the width of the elastic scattering peak is determined from the relationship between the corrected atomic number and the position of the elastic scattering peak and the relationship between the corrected atomic number and the width of the elastic scattering peak.

5. obtaining a backscattered electron spectrum of the sample; a step of separating the elastic scattering peak of the backscattered electron spectrum into a plurality of peaks by waveform separation, and acquiring information on the position, width, and intensity of each peak; identifying each element constituting the sample from the position and width of each peak; Evaluation methods, including:

6. an electron optical system that irradiates an electron beam onto a sample; an electron spectroscopic analyzer that detects reflected electrons emitted from the sample by spectroscopy; a control unit that controls the electron optical system; Including, The control unit obtaining a backscattered electron spectrum of the sample; A process of separating the elastic scattering peak of the backscattered electron spectrum into a plurality of peaks by waveform separation, and acquiring information on the position, width, and intensity of each peak; a process of identifying each element constituting the sample from the position and width of each peak; A process of determining the density of each element constituting the sample from the intensity of each peak; An analytical device that performs the above.

7. In claim 6, The control unit In the process of acquiring the backscattered electron spectrum, a spectral image is acquired in which the position of the measurement point on the sample and the backscattered electron spectrum are associated with each other; In the waveform separation process, an elastic scattering peak of the backscattered electron spectrum is waveform separated for each of the measurement points; In the process of identifying each element constituting the sample, each element is identified for each of the measurement points; An analytical apparatus for determining the density of each element constituting the sample, wherein the density of each element is determined for each of the measurement points.

8. an electron optical system that irradiates an electron beam onto a sample; an electron spectroscopic analyzer that detects reflected electrons emitted from the sample by spectroscopy; a control unit that controls the electron optical system; Including, The control unit obtaining a backscattered electron spectrum of the sample; A process of separating the elastic scattering peak of the backscattered electron spectrum into a plurality of peaks by waveform separation, and acquiring information on the position, width, and intensity of each peak; a process of identifying each element constituting the sample from the position and width of each peak; An analytical device that performs the above.

Images