JP7018365B2 - Charged particle beam device and analysis method - Google Patents

Description

The present invention relates to a charged particle beam device and an analysis method.

It is widely known that electrons have particle and wave properties. In the transmission electron microscope, a method of using this to interfere with electrons in a sample to acquire a diffraction pattern and examine the crystal structure of the sample has been used for a long time.

A method for analyzing the crystal orientation of a sample using the wave nature of electrons has also been established in a scanning electron microscope.

As such a method, for example, an EBSD (Electron Back Scatter Diffraction Patterns) method and an ECP (electron channeling pattern) method are known. First, the EBSD method will be described. When an electron beam is incident on the sample surface from about 70 °, the electrons are diffracted and emitted from the sample as backscattered electrons. The diffraction pattern appearing at this time is projected onto the EBSD detector, and the crystal orientation is analyzed from the obtained diffraction pattern (see, for example, Patent Document 1).

Next, the ECP method will be described. A signal from the sample is acquired while changing the incident angle of the electron beam, and an image is created with the electron beam incident angle and the signal amount to obtain interference fringes. The interference fringes reflect the crystal lattice of the sample, and by analyzing the interference fringes, information on the crystal orientation of the sample can be obtained.

Japanese Unexamined Patent Publication No. 2014-178154

Here, the EBSD method requires a dedicated detector for acquiring a diffraction pattern. In addition, the spatial resolution was poor because the electrons were accelerated by a high acceleration voltage and incident on the sample.

Further, in the ECP method, since the incident angle is changed while irradiating an electron beam to one point, a special optical system is required for the irradiation system.

A backscattered electron image is used when simply evaluating the crystallinity of a sample, such as evaluating the size of crystal grains of a sample. The backscattered electron image is obtained by detecting the backscattered electron using a detector such as a semiconductor detector that acquires electrons having a relatively high energy of several keV or more. In the backscattered electron image, the strength of the contrast (channeling contrast) changes depending on the crystal orientation, so the size of the crystal grains can be determined.

For example, in iron ore materials, it is important to evaluate the size of crystal grains because the size of crystal grains affects the strength and performance. However, it is not always necessary to accurately determine the crystal orientation using the EBSD method and evaluate the crystal grains, and in many cases it is sufficient if the size of the crystal grains can be determined.

Therefore, the size of the crystal grains may be evaluated by acquiring the channeling contrast of the backscattered electron image, but in the backscattered electron image, the crystal grains in different directions may have the same brightness, so they are larger than the actual crystal grains. May be visible.

Further, although the crystal orientation is important in a semiconductor, for example, it is often sufficient to distinguish between 100 planes and other planes so that it can be determined whether or not the 100 planes are oriented in an appropriate direction. Using the EBSD method or the ECP method in these applications is excessive in terms of performance, and it takes time and effort to measure. Therefore, a simple and easy analysis method is required.

An object of the present invention is to provide a charged particle beam device and an analysis method capable of easily obtaining information on the crystallinity of a sample.

One aspect of the charged particle beam apparatus according to the present invention is
A plurality of detectors that detect charged particles diffracted by the sample by irradiating the sample with a charged particle beam, and
An intensity pattern information generation unit that generates intensity pattern information representing the intensities of the plurality of detection signals as a graphic based on the intensities of the plurality of detection signals output from the plurality of detection units.
A scanning deflector for scanning the sample with the charged particle beam,
A pattern analysis unit that analyzes the intensity pattern information associated with the incident position of the charged particle beam with respect to the sample, and a pattern analysis unit.
An image generation unit that generates a pattern analysis image showing the distribution of the crystal orientation of the sample based on the analysis result of the pattern analysis unit.
Including
The plurality of detectors are composed of a split detector in which the first to nth detection regions are formed by dividing the annular detection surface centered on the optical axis in the circumferential direction.
The first to nth detection signals are output from the first to nth detection regions, respectively.
The figure is a figure created by plotting the intensities of the first to nth detection signals on the intensity axes of the first to nth detection signals, respectively .

In such a charged particle beam device, it is possible to generate intensity pattern information capable of obtaining information on the crystallinity of the sample based on the intensities of a plurality of detection signals output from the plurality of detection units. Therefore, information on the crystallinity of the sample can be easily obtained.

One aspect of the analysis method according to the present invention is
A step of scanning a sample with a charged particle beam and detecting charged particles diffracted by the sample by irradiating the sample with the charged particle beam by a plurality of detection units.
A step of generating intensity pattern information representing the intensities of the plurality of detection signals as a graphic based on the intensities of the plurality of detection signals output from the plurality of detection units .
A step of analyzing the intensity pattern information associated with the incident position of the charged particle beam with respect to the sample, and
A step of generating a pattern analysis image showing the distribution of the crystal orientation of the sample based on the analysis result in the step of analyzing the intensity pattern information, and a step of generating the pattern analysis image.
Including
The plurality of detectors are composed of a split detector in which the first to nth detection regions are formed by dividing the annular detection surface centered on the optical axis in the circumferential direction.
The first to nth detection signals are output from the first to nth detection regions, respectively.
The figure is a figure created by plotting the intensities of the first to nth detection signals on the intensity axes of the first to nth detection signals, respectively .

In such an analysis method, it is possible to generate intensity pattern information capable of obtaining information on the crystallinity of the sample based on the intensities of a plurality of detection signals output from the plurality of detection units. Therefore, information on the crystallinity of the sample can be easily obtained.

The figure which shows the structure of the electron microscope which concerns on 1st Embodiment. The plan view which shows the electron detector schematically. The figure which shows the result of the simulation. The figure which shows the result of the simulation. The figure which shows the distribution of the signal strength in a split type detector. The graph which shows the intensity of the 1st to nth detection signals. The figure which shows the intensity pattern generated based on the intensity of the 1st to nth detection signals. The figure which shows the position which acquired the intensity pattern. The figure which compared the strength pattern a and the strength pattern b. The figure which compared the strength pattern a and the strength pattern c. A pattern analysis image when the intensity pattern in the pixel at the center of the field of view is used as the reference intensity pattern. A pattern analysis image when the intensity pattern in the pixel indicated by the arrow is used as the reference intensity pattern. A pattern analysis image generated using three reference intensity patterns. Reflected electron image of the sample. Grain boundary image of the sample. The flowchart which shows an example of the processing flow of the processing part of the electron microscope which concerns on 1st Embodiment. The figure which shows the structure of the electron microscope which concerns on 2nd Embodiment. The figure which compared the reference strength pattern and the analysis strength pattern when the crystal orientation is the same and the rotation angle of the crystal orientation is different. The figure which rotated the reference strength pattern by 112.5 ° and compared it with the analysis strength pattern. The figure which shows the signal strength of a detection area. The figure which shows the signal strength of a detection area. The flowchart which shows an example of the processing flow of the processing part of the electron microscope which concerns on 2nd Embodiment. The figure which shows the structure of the electron microscope which concerns on 3rd Embodiment. The flowchart which shows an example of the processing flow of the processing part of the electron microscope which concerns on 3rd Embodiment. The figure which shows the structure of the electron microscope which concerns on 4th Embodiment. The figure which shows the structure of the electron microscope which concerns on 5th Embodiment. The plan view which shows the electron detector schematically. The figure which shows the relationship between a diffraction pattern and an electron detector. The figure which shows an example of the intensity line profile. The figure for demonstrating the method of finding a reference line profile. The figure for demonstrating the method of finding a reference line profile. The flowchart which shows an example of the processing flow of the processing part of the electron microscope which concerns on 5th Embodiment. The figure for demonstrating the modification of the electron detector. The figure for demonstrating the modification of the electron detector. The figure for demonstrating the modification of the electron detector. The figure which shows the structure of the electron microscope which concerns on 6th Embodiment. The figure which shows the structure of the electron microscope which concerns on 7th Embodiment. The plan view which shows the two electron detectors schematically. The figure which shows the crystal grain boundary image schematically. The figure which shows the state which the inscribed circle was drawn on the grain boundary image schematically. The flowchart which shows an example of the processing flow of the processing part of the electron microscope which concerns on 7th Embodiment. The graph which shows the elastic scattering cross section of an electron with respect to an iron atom. A graph showing the depth at which the electrons emitted from the sample are scattered.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unreasonably limit the content of the present invention described in the claims. Moreover, not all of the configurations described below are essential constituent requirements of the present invention.

Further, in the following, as the charged particle beam apparatus according to the present invention, a scanning electron microscope that irradiates an electron beam to observe and analyze a sample will be described as an example, but the charged particle beam apparatus according to the present invention will be described. It may be a device for observing or analyzing a sample by irradiating a charged particle beam (ion or the like) other than an electron beam.

1. 1. First Embodiment 1.1. Electron Microscope First, the electron microscope according to the first embodiment will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of an electron microscope 100 according to a first embodiment.

As shown in FIG. 1, the electron microscope 100 includes an electron source (an example of a charged particle beam source) 2, a focusing lens 3, an objective lens 4, a scanning deflector 5, a sample stage 6, and an electron detector 8. The scanning signal generator 10, the amplifier 12, the signal regulator 14, the signal acquisition unit 16, the signal converter 18, the operation unit 20, the display unit 22, the storage unit 24, and the processing unit 30. ,including.

The electron source 2 generates electrons. The electron source 2 is, for example, an electron gun that accelerates electrons emitted from a cathode by an anode and emits an electron beam (an example of a charged particle beam).

The focusing lens 3, together with the objective lens 4, converges the electron beam emitted from the electron source 2 to form an electron probe (an example of a charged particle probe). The convergent lens 3 can control the diameter of the electron probe and the probe current (irradiation current amount).

The objective lens 4 is a lens for forming an electron probe arranged immediately before the sample S. The objective lens 4 includes, for example, a coil and a yoke. In the objective lens 4, the magnetic force lines made of the coil are confined in a yoke made of a material having high magnetic permeability such as iron, and a notch is made in a part of the yoke to make the magnetic force lines distributed in high density the optical axis. Leak on OA.

The scanning deflector 5 deflects an electron probe (converged electron beam) formed by the converging lens 3 and the objective lens 4. The scanning deflector 5 is an electron probe used for scanning on the sample S. The scanning deflector 5 is driven based on the scanning signal generated by the scanning signal generator 10 to deflect the electron beam. As a result, the sample S can be scanned with the electron probe.

The sample S is placed on the sample stage 6. The sample stage 6 supports the sample S. The sample stage 6 has a drive mechanism for moving the sample S.

The electron detector 8 detects electrons scattered and diffracted by the sample S when the sample S is irradiated with an electron beam. When an electron is incident on the crystalline sample S, the electron is scattered and then diffracted on the lattice plane of the crystal to emit the diffracted electron (reflected electron). In the electron microscope 100, the back electron including the diffracted electron is detected by the electron detector 8.

FIG. 2 is a plan view schematically showing the electron detector 8. As shown in FIG. 2, the electron detector 8 is a split type detector having n detection regions 9 (an example of a detection unit). However, n is an integer of 2 or more, preferably an integer of 5 or more. In the illustrated example, n = 16. The n detection regions 9 can independently detect electrons. That is, each of the n detection regions 9 outputs a detection signal according to the amount of detected electrons. Specifically, the first detection signal is output from the first detection area 9, the second detection signal is output from the second detection area 9, and the nth detection signal is output from the nth detection area 9. It is output. In the example shown in FIG. 2, the electron detector 8 has 16 detection regions 9 formed by dividing the annular detection surface in the circumferential direction. The electron detector 8 is arranged on the optical axis OA. In the electron detector 8, the optical axis OA is arranged so as to pass through the center of the annular detection surface.

The shape of the detector (detection surface) and the number of divisions are not limited to the example shown in FIG. Further, as the electron detector 8, instead of the split type detector, a plurality of electron detectors having one detection area may be arranged. In this case, one electron detector constitutes one detection unit.

Further, in the example shown in FIG. 1, the electron detector 8 is arranged directly under the objective lens 4, but the position of the electron detector 8 is particularly high if it can detect the reflected electrons diffracted by the sample S. Not limited.

For example, although not shown, in the electron microscope 100, as the objective lens 4, a lens (snorkel lens) whose resolution at a low acceleration voltage is improved by positively generating a magnetic field of the lens up to the vicinity of the sample S is used. In this case, the electron detector 8 may be arranged in the objective lens 4. In this case, the electrons emitted from the sample S easily pass through the center hole of the objective lens 4 and easily reach the inside of the objective lens 4.

In the electron microscope 100, the electron beam emitted from the electron source 2 is converged by the focusing lens 3 and the objective lens 4 to form an electron probe, and the electron beam is deflected by the scanning deflector 5, so that the sample S is used by the electron probe. Scan above. As a result, the electrons incident on the sample S are scattered in the sample S and then diffracted by the lattice plane of the crystal. The diffracted electrons (reflected electrons) are emitted from the sample S, and a diffraction pattern (Kikuchi pattern) is formed on the detection surface of the electron detector 8. The reflected electrons emitted from the sample S are detected by the electron detector 8.

The detection signal output from the detection area 9 of the electron detector 8 is amplified by the amplifier 12. The amplification factor, offset amount, and the like of the detected signal in the amplifier 12 are adjusted by the signal regulator 14.

The signal acquisition unit 16 acquires the amplified detection signal. The signal acquisition unit 16 simultaneously acquires, for example, the first to nth detection signals output from the n detection regions 9. The signal acquisition unit 16 receives the scanning signal from the scanning signal generator 10 and acquires information on the incident position of the electron beam in the sample S. In the signal acquisition unit 16, the detection signal is associated with the information on the incident position of the electron beam. The signal acquisition unit 16 can be realized by, for example, a dedicated circuit.

The detection signal associated with the incident position of the electron beam output from the signal acquisition unit 16 is converted into a signal readable by the processing unit 30 in the signal converter 18.

The operation unit 20 acquires an operation signal corresponding to the operation by the user and performs a process of sending the operation signal to the processing unit 30. The operation unit 20 is, for example, a button, a key, a touch panel type display, a microphone, or the like.

The display unit 22 displays the image generated by the processing unit 30. The display unit 22 can be realized by a display such as an LCD (Liquid Crystal Display).

The storage unit 24 stores programs, data, and the like for the processing unit 30 to perform various calculation processes and control processes. Further, the storage unit 24 is used as a work area of the processing unit 30, and is also used to temporarily store the calculation results and the like executed by the processing unit 30 according to various programs. The storage unit 24 can be realized by, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), and a hard disk.

The processing unit 30 performs various control processing and calculation processing according to the program stored in the storage unit 24. The function of the processing unit 30 can be realized by executing a program on various processors (CPU (Central Processing Unit) or the like). The processing unit 30 includes an intensity pattern information generation unit 32, a pattern analysis unit 33, and an image generation unit 34.

The intensity pattern information generation unit 32 generates intensity pattern information based on the intensities of the first to nth detection signals output from the n detection regions 9. The intensity pattern information represents the intensity of the first to nth detection signals as a figure as described later. It should be noted that the intensity pattern information includes not only the information of the figure itself, but also the information of the matrix when the figure is represented as a matrix, the information of the formula when the figure is represented as a formula, and the like.

The pattern analysis unit 33 compares the intensity patterns generated by the intensity pattern information generation unit 32 with each other to generate pattern analysis information.

The image generation unit 34 generates an image based on the pattern analysis information associated with the incident position of the electron beam with respect to the sample S. The image generated by the image generation unit 34 based on the pattern analysis information includes a crystal orientation image showing the distribution of the crystal orientation of the sample S, which will be described later, and a crystal grain boundary image obtained by extracting the grain boundaries of the crystal grains.

The processing of the intensity pattern information generation unit 32, the processing of the pattern analysis unit 33, and the processing of the image generation unit 34 will be described later.

1.2. Principle First, the principle of analysis in the electron microscope 100 will be described.

When an electron is incident on a crystalline sample, the electron is scattered and diffracted, and the diffracted electron (reflected electron) is emitted from the sample. When the backscattered electrons subjected to this diffraction are detected by a scanning electron microscope and a scanned electron image is acquired, a channeling contrast whose brightness changes depending on the crystal orientation can be obtained. Even if the electron irradiation conditions are the same, if the position of the detector is changed, electrons that receive diffraction differently will be detected, and the channeling contrast will also change. Therefore, the backscattered electrons can be detected by using a plurality of backscattered electron detectors, and the crystal orientation of the sample can be analyzed from the intensity of the detection signal of each backscattered electron detector.

1.2.1. Simulation Simulation confirmed that there is a difference in signal strength due to diffraction depending on the position of the detector.

The contents of the simulation are as follows.

As a detector of the scanning electron microscope, as shown in FIG. 2, an annular backscattered electron detector divided into 16 equal parts in the circumferential direction was used and placed above the sample (see FIG. 1). Assuming that a diffraction pattern is formed in the backscattered electron detector, the intensities of the backscattered electrons detected at a predetermined time are integrated in each detection region to obtain the signal strength in each detection region.

3 and 4 are diagrams showing the results of the simulation. FIG. 3 shows the signal intensity of each detection region when the sample is a crystal in a certain direction. FIG. 4 shows the signal intensity of each detection region when the orientation of the crystal is changed in the same sample. In FIGS. 3 and 4, the bright region has a large amount of signal, and the dark region has a small amount of signal. As a result of the simulation, it was found that the signal intensity in each detection region differs depending on the crystal orientation of the sample.

1.2.2. Example Next, as shown in FIG. 2, an annular backscattered electron detector divided into 16 equal parts in the circumferential direction is prepared and mounted on a scanning electron microscope, and each of the divided detectors is mounted according to the crystal orientation of the sample. It was investigated whether the signal strength in the detection area was different.

FIG. 5 is a diagram showing the distribution of signal strength in the split detector. The fan-shaped area indicates the detection area, and the fan-shaped brightness indicates the signal strength. Specifically, the bright detection area indicates that the signal amount is large, and the dark detection area indicates that the signal amount is small.

Looking at the distribution of signal intensities in the split detector, the distribution of signal intensities is similar within the same crystal grain, and the distribution of signal intensities is significantly different in crystal grains with different crystal orientations. Further, even if the crystal grains are separated from each other, the distribution of the signal intensity is similar in the crystal grains having the same crystal orientation.

From this, it was found that it is possible to analyze the crystal orientation of the crystal grains from the distribution of the signal intensity in the split detector.

1.3. Processing Next, the processing of the processing unit 30 of the electron microscope 100 will be described.

1.3.1. Acquisition of Detection Signal First, the process of acquiring the detection signal in the processing unit 30 will be described.

In the processing unit 30, the first to nth detection signals output from the n detection regions 9 acquired by the signal acquisition unit 16 are sent together with information on the incident position of the electron beam with respect to the sample S specified by the scanning signal. Entered.

The incident position of the electron beam with respect to the sample S is x, y, the number of detection regions 9 of the electron detector 8 is n, the detection regions z = 1, 2, ..., N, and the detection signals in x, y, z Let the signal strength be a three-dimensional array s (x, y, z). Hereinafter, this array s (x, y, z) is referred to as a signal strength array. The signal strength array s (x, y, z) is stored in the storage unit 24.

An image (scanned image) can be generated based on the signal intensity array s (x, y, z) acquired in this way.

For example, if an image is created using the sum of the incident position of the electron beam and the intensity of the detection signal of each detection region 9 at the incident position, the scanned image obtained by detecting the backscattered electron, that is, the backscattered electron image A similar image is obtained. This image can be expressed by the following equation, where i (x, y) is the array of images.

Further, as shown by the following equation, an image may be generated using the intensity of the detection signal of a single detection region 9.

Further, the detection signals in the plurality of detection areas 9 may be subjected to signal processing such as addition or subtraction to generate an image. The process of generating these images is performed by the image generation unit 34.

1.3.2. Method of generating strength pattern Next, a method of generating a strength pattern will be described. The strength pattern is generated by the strength pattern information generation unit 32.

The intensities of the first to nth detection signals (hereinafter, also simply referred to as “signal intensities”) have the same signal intensities in the same crystal orientation. Therefore, by comparing the signal strength of an arbitrary position on the sample S (hereinafter, also referred to as “reference position”) with the signal strength of another position on the sample S (hereinafter, also referred to as “analysis position”), the signal strength can be compared. It can be determined whether or not the crystal orientation at the reference position and the crystal orientation at the analysis position are the same.

Crystallinity is evaluated by generating an intensity pattern from the signal intensity at the reference position and the signal intensity at the analysis position, and comparing these two patterns. The method will be described below.

First, an example of a method of converting signal strength into an intensity pattern will be described.

Assuming that the number of detection regions 9 is n, the intensities of the first to nth detection signals at a certain incident position x, y are expressed by using the signal intensity array s, d ₁ = s (x, y, 1). , D ₂ = s (x, y, 2), ..., d _n = s (x, y, n).

FIG. 6 is a graph showing the intensities of the first to nth detection signals. In FIG. 6, n = 16.

When the smallest value among d ₁ , d ₂ , ..., D _n is d _min , the intensity pattern a can be obtained by the following equation.

a = (d ₁ / d _min , d ₂ / d _min , ..., d _n / d _min )

In this way, the strength of the first to nth detection signals is standardized by the strength of the detection signal having the smallest value. Thereby, the strength of the first to nth detection signals can be obtained. From this signal strength, the strength pattern a (an example of strength pattern information) represented by the above matrix can be obtained.

FIG. 7 is a diagram showing an intensity pattern generated based on the intensity of the first to nth detection signals shown in FIG. 6 on a radar chart.

In FIG. 7, the origins of the intensity axes of the first to nth detection signals are grouped into one and radially formed, and the intensity of the first to nth detection signals standardized on the intensity axes of the first to nth detection signals is shown in FIG. Is plotted and the points next to each other are connected by a straight line to form a figure.

The generated intensity pattern is stored in the storage unit 24 for each pixel of the scanned image associated with the incident position of the electron beam.

Next, a modified example of the method of generating the strength pattern will be described.

In the above, the first to nth detection signals are standardized with the minimum value d _min to generate the intensity pattern, but the method of generating the intensity pattern is not limited to this.

For example, when the smallest value is d _min and the largest value is d _max from d ₁ , d ₂ , ..., D _n , the intensity pattern a may be obtained by the following equation. ..

a = ((d ₁ − d _min ) / (d _max − d _min ), (d ₂ − d _min ) / (d _max − d _min ), ···, (d _n − d _min ) / (d _max ) -D _min )))

Here, under the condition that the current amount of the electron beam is small, the SN ratio (Signal to Noise Ratio) of the detection signal becomes poor, and the accuracy of the pattern analysis (also referred to as pattern recognition) described later is lowered. Therefore, a matrix obtained by averaging the intensity patterns around the analysis position may be used as the intensity pattern. As a result, the accuracy of pattern analysis can be improved. As described above, when the intensity pattern is generated, a process for improving the accuracy of the pattern analysis may be performed.

For example, in the above example, the number n of the detectors and the size of the row example representing the intensity pattern a are the same, but as shown in the following equation, the number n of the detectors and the matrix representing the intensity pattern a are used. The sizes of are not necessarily the same.

For example, the average of the intensities of the first to nth detection signals may be added as an element of the intensity pattern. In this case, since the average of the intensities of the first to nth detection signals is added to the pattern generated by using the intensities of the first to nth detection signals for the number n of the detectors, the element of the obtained intensity pattern. The number is n + 1.

Here, for example, as shown in FIG. 2, in a split type detector having an annular detection surface, when the sample surface is not parallel to the detection surface, the signal intensity is affected by the inclination of the sample surface. , Affects pattern analysis. Therefore, when the intensity pattern is generated by taking the difference in the intensity of the detection signals of the adjacent detection regions 9, for example, as shown in the following equation, the signal due to the crystal orientation due to diffraction is compared with the difference in the signal intensity due to the inclination of the sample surface. Since the difference in intensity is emphasized, the accuracy of pattern analysis is improved.

a = ((d ₁ − d _n ) / d _min , (d ₂ − d ₁ ) / d _min , ···, (d _n − d _n-1 ) / d _min )

Further, for example, if the dose amount of the electron beam is small, noise may be added to the intensity pattern due to a statistical error and the pattern may not be analyzed correctly. Therefore, the intensity pattern may be generated by averaging the signal intensities around the incident position of the electron beam. As a result, the statistic can be increased and the noise can be reduced, so that the accuracy of the pattern analysis can be improved.

1.3.3. Comparison of Intensity Patterns Next, a method of comparing the generated intensity pattern with a reference intensity pattern to evaluate the similarity of the patterns will be described. This process is performed by the pattern analysis unit 33.

FIG. 8 is a diagram showing a position where the strength pattern is acquired. FIG. 9 is a diagram comparing the intensity pattern a obtained at the point p1 of FIG. 8 and the intensity pattern b obtained at the point p2 of FIG. In FIG. 9, the strength pattern a is shown by a solid line, and the strength pattern b is shown by a broken line. FIG. 10 is a diagram comparing the intensity pattern a obtained at the point p1 of FIG. 8 and the intensity pattern c obtained at the point p3 of FIG. In FIG. 10, the strength pattern a is shown by a solid line, and the strength pattern c is shown by a broken line.

Since the intensity pattern a and the intensity pattern b are similar in FIG. 9, it can be said that the crystal orientation at the point p1 and the crystal orientation at the point p2 are the same. On the other hand, in FIG. 10, since the intensity pattern a and the intensity pattern c are not similar, it can be said that the crystal orientation at the point p1 and the crystal orientation at the point p3 are different.

As shown in FIGS. 9 and 10, if the two intensity patterns are overlapped and visually confirmed, the similarity of the patterns can be easily understood. However, it is difficult to visually confirm all the intensity patterns generated for the evaluation of crystallinity. Therefore, the pattern analysis unit 33 mathematically compares the patterns.

Here, a case where the Euclidean distance is used as a method of pattern analysis will be described. The method of pattern analysis is not limited to this, and other known method of pattern analysis (for example, a method using a nearest neighbor rule) can also be applied.

First, a reference strength pattern (hereinafter, also referred to as “reference strength pattern”) is determined. The reference strength pattern is, for example, a strength pattern selected from the generated strength patterns. That is, as the reference intensity pattern, one intensity pattern among the plurality of intensity patterns generated corresponding to the plurality of pixels constituting the scanned image is used.

For example, the reference intensity pattern may be an intensity pattern in a pixel located at the center of the scanned image. Further, the reference intensity pattern may be an intensity pattern in any pixel of the scanned image.

When the intensity pattern of the pixel to be analyzed (hereinafter, also referred to as “analysis intensity pattern”) is a and the reference intensity pattern is b, the Euclidean distance D between the reference intensity pattern b and the analysis intensity pattern a is obtained. It is possible to judge the similarity of patterns.

The Euclidean distance D is calculated by the following equation (1).

Here, a _i is an element of the analysis intensity pattern a, and _bi is an element of the reference intensity pattern b. n is the number of elements of the intensity pattern. Here, n is the same as the number of detection regions 9, but it is not always the same. It can be said that the smaller the Euclidean distance D, the more similar the analysis intensity pattern a and the reference intensity pattern b are. If the Euclidean distance D from the reference intensity pattern b is equal to or less than a predetermined value in the pixel to be analyzed in consideration of the variation in the pattern due to noise or the like, the pixel to be analyzed has the same crystal orientation as the reference intensity pattern. Judge that.

1.3.4. Image generation Next, an image generation method will be described. The process of generating an image is performed by the image generation unit 34.

(1) Generation of pattern analysis image First, a method of generating an image reflecting the result of pattern analysis (hereinafter, also referred to as “pattern analysis image”) will be described.

In the following, any pixel of the scanned image is defined as (x, y), the intensity pattern in the pixel is defined as ax _{, y} , and the analysis result obtained by the pattern analysis unit 33 is defined as the Euclidean distance D _{x, y} . Here, the Euclidean distances of the reference intensity pattern and the analysis intensity pattern ax _{, y} are Dx _{, y} .

When there are regions of crystal orientation cd1 and crystal orientation cd2 in the observation field, the intensity pattern of crystal orientation cd1 is set as the reference intensity pattern b, and the reference intensity pattern b is used in a plurality of pixels included in the region of crystal orientation cd2. Euclidean distance D _{x, y} of. Since these pixels are included in the region of the same crystal orientation cd2, the Euclidean distances Dx _{and y} are close to each other. For example, when a plurality of pixels are (x1, y1) and (x2, y2), the intensity patterns in the respective pixels are a _{x1, y1} and a _{x2, y2} . Since (x1, y1) and (x2, y2) are points within the same crystal orientation, the intensity patterns of a _{x1, y1} and a _{x2, y2} are similar. Therefore, the Euclidean distances D _{x1 and y1} and the Euclidean distances D _{x2 and y2} of the respective intensity patterns and the reference intensity patterns b are also close to each other.

Therefore, the intensity pattern of an arbitrary point (for example, the center of the visual field) in the observation field of view is set as the reference intensity pattern b, and the Euclidean distances _{Dx and y} with the reference intensity pattern b are obtained in each pixel constituting the scanned image. Then, when an image is generated in which the size of the Euclidean distance D _{x, y} in each pixel corresponds to the brightness, an image (pattern analysis image) in which crystal grains having different crystal orientations are displayed with different brightness is obtained.

FIG. 11 is a pattern analysis image when the intensity pattern in the pixel at the center of the visual field is set as the reference intensity pattern b. FIG. 12 is a pattern analysis image when the intensity pattern in the pixel indicated by the arrow is set as the reference intensity pattern b.

As shown in FIGS. 11 and 12, if the reference intensity pattern b is different, the obtained pattern analysis image is different. In the illustrated example, when the reference intensity pattern b and the analysis intensity pattern a are similar (that is, when the Euclidean distance D _{x, y} is small), the pixel is dark, and when the reference intensity pattern b and the analysis intensity pattern a are not similar (that is, when the analysis intensity pattern a is small). (When the Euclidean distance D _{x, y} is large) The pixel becomes bright. However, in this method, bright pixels do not always have similar intensity patterns.

Therefore, more accurate pattern analysis can be performed by preparing a plurality of reference intensity patterns and obtaining the Euclidean distances D _{x, y} for each of the plurality of reference intensity patterns.

For example, first, the intensity pattern in any pixel is set as the reference intensity pattern b1, and the Euclidean distance D1 _{x, y} with the reference intensity pattern b1 is obtained in each pixel constituting the scanning image.

Next, the pixel having the maximum Euclidean distance D1 _{x, y} is selected from the plurality of pixels constituting the scanned image, and the intensity pattern in the pixel is set as a new reference intensity pattern b2. Then, in each pixel constituting the scanned image, the Euclidean distance D2 _{x, y} with the reference intensity pattern b2 is obtained.

Next, the pixel having the maximum sum of the Euclidean distance D1 _{x, y} and the Euclidean distance D2 _{x, y} is selected from the plurality of pixels constituting the scanned image, and the intensity pattern in the pixel is used as a new reference intensity pattern. Let it be b3. Then, in each pixel constituting the scanned image, the Euclidean distance D3 _{x, y} with the reference intensity pattern b3 is obtained.

Next, the brightness of each pixel constituting the scanning image is made to correspond to the magnitude of the Euclidean distances D1 _{x, y} to form the first scanning image. At this time, red is assigned to the first scanned image. Similarly, the brightness of each pixel constituting the scanning image is made to correspond to the magnitude of the Euclidean distances D2 _{x, y} to form the second scanning image. At this time, green is assigned to the second scanned image. Similarly, the brightness of each pixel constituting the scanning image is made to correspond to the magnitude of the Euclidean distances D3 _{x, y} to form the third scanning image. At this time, blue is assigned to the third scanning image.

Next, the first scan image, the second scan image, and the third scan image are superposed to form one image. As a result, a pattern analysis image of the sample S generated by using the three reference intensity patterns b1, b2, and b3 can be obtained.

FIG. 13 is a pattern analysis image of the sample S generated by using three reference intensity patterns.

As shown in FIG. 13, in the pattern analysis image generated by using three reference intensity patterns, the pixels having high pattern similarity have similar colors. That is, the pixels represented by the same color in FIG. 13 show that they have the same crystal orientation. In FIG. 13, since three reference intensity patterns are used, the difference in crystal orientation can be reflected more accurately in the image as compared with the case where one reference intensity pattern is used, for example.

FIG. 14 is a backscattered electron image of the sample S. The pattern analysis image shown in FIG. 13 and the reflected electron image shown in FIG. 14 have the same field of view.

As shown in FIG. 14, even in the backscattered electron image, the crystal grains can be discriminated by the channeling contrast, but the boundary is difficult to understand when the crystal grains having similar contrasts are adjacent to each other. On the other hand, in the pattern analysis image shown in FIG. 13, the boundaries of the crystal grains are clearer than those of the backscattered electron image.

Although the case of generating a pattern analysis image using three reference intensity patterns has been described here, the number of reference intensity patterns used to generate the pattern analysis image is not particularly limited. Further, the method of selecting the reference strength pattern is not limited to the above example.

(2) Generation of crystal grain boundary image Next, a method of generating an image from which the crystal grain boundary is extracted (hereinafter, also referred to as “crystal grain boundary image”) will be described.

The intensity pattern in any pixel (x, y) is used as a reference intensity pattern, and the Euclidean distance from the reference intensity pattern is obtained in the pixels around the reference intensity pattern and the total is calculated. If the pixels around the pixel (x, y) have different crystal orientations, the total Euclidean distance will be large. Therefore, the presence or absence of grain boundaries can be determined from the total Euclidean distance. Hereinafter, a method for generating a grain boundary image will be described more specifically.

In the scanned image, the reference pixel is defined as a reference pixel (x, y), and the intensity pattern in the reference pixel is defined as a reference intensity pattern. Then, the Euclidean distance is obtained for the pixels (x, y-1), (x-1, y), (x + 1, y), and (x, y + 1) around the reference pixel (x, y).

Here, the range of x is 0 to xmax, and the range of y is 0 to ymax. In the case of the reference pixel (0,0), the surrounding pixels are (0, -1), (-1,0), (1,0), (0,1), which is outside the above range. , The reference pixel is set so that the surrounding pixels are within the above range.

First, the Euclidean distance is calculated for each of the surrounding pixels (1,0), (0,1), (2,1), and (1,2) as the reference pixel (1,1), and these The total Db ₁ , 1 is calculated.

Specifically, first, the Euclidean distance between the intensity pattern in the reference pixel (1,1) and the intensity pattern in the pixel (1,0) is calculated. Similarly, the Euclidean distance between the intensity pattern in the reference pixel (1,1) and the intensity pattern in the pixel (0,1), and the Euclidean distance between the intensity pattern in the reference pixel (1,1) and the intensity pattern in the pixel (2,1). , The Euclidean distance of the intensity pattern in the reference pixel (1,1) and the intensity pattern in the pixel (1,2) is calculated. Then, the total Db ₁ , 1 of the calculated four Euclidean distances is obtained.

Similarly, the Euclidean distance is calculated for each of the surrounding pixels (2,0), (1,1), (3,1), and (2,2) with the reference pixel (2,1) as the reference pixel, and the sum of these is calculated. Find Db _2,1 . This process is performed on all pixels of the scanned image in which the Euclidean distance to the surrounding pixels can be calculated.

In this way, for all the pixels of the scanned image in which the Euclidean distance to the surrounding pixels can be calculated, the Euclidean distance is calculated for each of the surrounding pixels while changing the pixel as the reference pixel, and the total is calculated. I do. As a result, the total Db ₁ , 1, the total Db ₂ , 1, ..., The total Db _xmax-1 , _ymax-1 can be obtained.

Next, an image is generated using the total Db ₁ , 1, the total Db ₂ , 1, ..., The total Db _xmax-1 , _ymax-1 . For example, the maximum value and the minimum value are obtained from the total Db ₁ , 1, total Db ₂ , 1, ..., Total Db _xmax-1 , _ymax-1 , and the maximum value is white and the minimum value is black. The brightness of the image is represented by a gray scale as an image. As a result, a grain boundary image in which the grain boundaries are emphasized can be obtained.

FIG. 15 is a grain boundary image of sample S. As shown in FIG. 15, in the crystal grain boundary image, the crystal grain boundaries are highlighted in white and displayed.

The method for generating the grain boundary image is not limited to the above method. For example, for total Db ₁ , 1, total Db ₂ , 1, ..., Total Db _xmax-1 , _ymax-1 , if the value is equal to or more than a predetermined value, it is regarded as white, and if it is less than a predetermined value, it is regarded as black. By generating an image, a grain boundary image may be generated.

Further, in the above description, the case where the Euclidean distance is calculated for the upper, lower, left, and right pixels of the reference pixel (x, y) has been described, but the range of the surrounding pixels for which the Euclidean distance is calculated may be further expanded. .. For example, when the grain boundary is large, the surrounding pixels for which the Euclidean distance is calculated may be pixels far from the reference pixel.

Further, when the noise of the detection signal is large, the Euclidean distance may be increased due to the influence of the noise, and it may be erroneously recognized as a grain boundary. Therefore, the average of the intensity pattern in the reference pixel and the intensity pattern in the surrounding pixels may be used as the reference intensity pattern. As a result, the influence of noise can be reduced.

Further, when it is desired to observe the crystal grain boundary image in real time, the signal intensity array s (x, y, z) is acquired while scanning the electron probe. Then, the pixel corresponding to the incident position of the electron beam is defined as a reference pixel (x, y), and the pixels (x, y-1) and (x-1, y) corresponding to the region through which the electron beam has already passed are referred to. The Euclidean distance may be calculated and the sum thereof may be calculated to generate a grain boundary image. As described above, the method of taking the surrounding pixels is not particularly limited.

(3) Measurement of crystal grain size The crystal grain size can be measured by using the intensity pattern stored for each pixel constituting the scanned image. The process of measuring the size of the crystal grains is performed by the image generation unit 34.

For example, when the user wants to know the size of the crystal grain, if an arbitrary pixel containing the crystal grain is specified as the reference pixel in the scanned image, the intensity pattern in the reference pixel in the other pixels constituting the scanned image ( By obtaining the Euclidean distance from the reference strength pattern), the size of the crystal grains can be measured. The method will be described below.

The Euclidean distance D _{x, y} is obtained for all the pixels of the scanned image, using the intensity pattern in the pixel specified by the user as the reference intensity pattern. Pixels (x, y) in which the Euclidean distance D _{x, y} is equal to or less than a predetermined value have the same orientation, but may be different as crystal grains. Therefore, a region including pixels (x, y) and having an Euclidean distance D _{x, y} of a predetermined value or less is extracted. The number of pixels in the extracted area is obtained, and the area per pixel is calculated from the scan width. Then, the area of the designated crystal grain is obtained from the product of the number of pixels and the area per pixel.

1.4. Process flow Next, the process flow of the processing unit 30 of the electron microscope 100 according to the first embodiment will be described. FIG. 16 is a flowchart showing an example of the processing flow of the processing unit 30 of the electron microscope 100 according to the first embodiment.

In the electron microscope 100, the sample S is scanned by the electron probe, the reflected electrons from the incident position of the electron beam are detected in the plurality of detection regions 9, and each incident position (that is, each pixel constituting the scanned image). , The first to nth detection signals output from the n detection regions 9 are acquired.

The first to nth detection signals acquired by the signal acquisition unit 16 are input to the processing unit 30 together with information on the incident position of the electron beam with respect to the sample S specified by the scanning signal.

The intensity pattern information generation unit 32 generates an intensity pattern based on the intensity of the first to nth detection signals (S100).

Specifically, the intensity pattern information generation unit 32 acquires the intensities d ₁ , d ₂ , ..., D _n of the first to nth detection signals, and the intensities d ₁ , of the first to nth detection signals. By standardizing d ₂ , ..., d _n , the intensity pattern a = (d ₁ / d _min , d ₂ / d _min , ..., d _n / d) based on the intensity of the first to nth detection signals. _min ) is generated.

The intensity pattern information generation unit 32 performs the above processing for each incident position of the electron beam (that is, for each pixel constituting the scanning image) to generate an intensity pattern. The intensity pattern information generation unit 32 stores the generated intensity pattern in the storage unit 24 in association with the incident position of the electron beam. That is, the intensity pattern a is stored in the storage unit 24 corresponding to each of the plurality of pixels constituting the scanned image.

Next, the pattern analysis unit 33 generates pattern analysis information for each incident position of the electron beam based on the intensity pattern a stored in the storage unit 24 (S102).

For example, when generating a pattern analysis image, the pattern analysis unit 33 obtains the Euclidean distance from the reference reference intensity pattern for each pixel constituting the scanned image. This Euclidean distance is used as pattern analysis information.

Further, for example, when generating a crystal grain boundary image, the pattern analysis unit 33 changes the pixels as reference pixels for all the pixels of the scanned image in which the Euclidean distance to the surrounding pixels can be calculated, and the surroundings thereof. The Euclidean distance is calculated for each of the pixels of, and the total is calculated. This total is used as pattern analysis information.

Next, the image generation unit 34 generates an image based on the pattern analysis information generated by the pattern analysis unit 33 (S104).

For example, when generating a pattern analysis image, the image generation unit 34 sets the brightness of the pixels according to the Euclidean distance and generates the pattern analysis image.

Further, for example, when generating a crystal grain boundary image, the image generation unit 34 sets the brightness of the pixels according to the total value of the Euclidean distances obtained by the analysis in the pattern analysis unit 33, and sets the crystal grain boundary image. To generate.

The image generation unit 34 controls to display the generated image on the display unit 22 (S106).

1.5. Features The electron microscope 100 has the following features, for example.

The electron microscope 100 includes an electron detector 8 having a plurality of detection regions 9 for detecting electrons diffracted by the sample S by irradiating the sample S with an electron beam, and a first output from the plurality of detection regions 9. It includes an intensity pattern information generation unit 32 that generates an intensity pattern based on the intensity of the 1st to nth detection signals. Since the electron microscope 100 can generate an intensity pattern based on the intensity of the first to nth detection signals, for example, a dedicated detector for measuring by the EBSD method or a measurement by the ECP method is performed. No special irradiation system is required for this purpose, and information on the crystallinity of the sample S can be easily obtained.

Further, in the electron microscope 100, since the measurement can be performed by detecting the backscattered electrons by the electron detector 8 provided with the plurality of detection regions 9, the measurement can be performed in a shorter time than the measurement by the EBSD method or the ECP method, for example. Is possible.

For example, when the size of a crystal grain is evaluated by acquiring a backscattered electron image, the size of the crystal grain cannot be accurately evaluated because different crystal grains may be displayed with the same brightness. On the other hand, in the electron microscope 100, since the image is generated from the intensity pattern, such a problem does not occur. Therefore, in the electron microscope 100, it is possible to obtain an image (pattern analysis image, grain boundary image) in which the size of the crystal grain can be evaluated more accurately than the reflected electron image.

In the electron microscope 100, the scanning deflector 5 for scanning on the sample S with the electron probe, the pattern analysis unit 33 for analyzing the intensity pattern associated with the incident position of the electron beam with respect to the sample S, and the pattern analysis unit 33 are used. The image generation unit 34, which generates an image based on the analysis result of the intensity pattern of the above, is included. Therefore, the electron microscope 100 can obtain a pattern analysis image reflecting the crystal orientation of the sample S and a crystal grain boundary image from which the crystal grain boundaries are extracted. Therefore, in the electron microscope 100, the crystallinity information of the sample S can be easily obtained in a short time.

In the electron microscope 100, the pattern analysis unit 33 acquires reference intensity pattern information based on the intensity pattern associated with the incident position of the electron beam with respect to the sample S. Therefore, in the electron microscope 100, for example, by generating a pattern analysis image using the intensity pattern of the crystal grain of interest as a reference intensity pattern, it is possible to visualize the difference in crystal orientation between the crystal grain of interest and another crystal grain. can.

In the electron microscope 100, the pattern analysis unit 33 compares the reference intensity pattern as a reference with the generated intensity pattern, and the image generation unit 34 generates a crystal grain boundary image from which the grain boundaries of the sample S are extracted. Therefore, with the electron microscope 100, the crystal grain boundary image of the sample S can be easily obtained in a short time.

In the electron microscope 100, the electrons diffracted by the sample S are detected by a split detector (electron detector 8) having a plurality of detection regions 9. Therefore, the electron microscope 100 can measure in a short time as compared with the measurement by, for example, the EBSD method or the ECP method.

In the electron microscope 100, the intensity pattern information generation unit 32 normalizes the intensities of the plurality of detection signals output from the plurality of detection regions 9 to generate an intensity pattern. Therefore, the electron microscope 100 can easily obtain crystallinity information.

2. 2. Second Embodiment 2.1. Electron Microscope Next, the electron microscope according to the second embodiment will be described with reference to the drawings. FIG. 17 is a diagram showing the configuration of the electron microscope 200 according to the second embodiment. Hereinafter, in the electron microscope 200 according to the second embodiment, the members having the same functions as the constituent members of the electron microscope 100 according to the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

In the electron microscope 200, as shown in FIG. 17, the storage unit 24 stores a database 26 in which a reference intensity pattern is registered for each crystal orientation.

As described above, if the crystal orientation is the same, the intensity pattern is also the same. Therefore, by using the intensity pattern of the sample whose crystal orientation is known as the reference intensity pattern and comparing the analysis intensity pattern of the analysis position with the reference intensity pattern, the crystal orientation of the analysis position is the same as the crystal orientation of the reference intensity pattern. It is possible to judge whether or not it is.

Therefore, a database 26 in which a reference intensity pattern is registered is prepared for each composition of the sample and the crystal orientation of the sample, and is stored in the storage unit 24 in advance. The reference intensity pattern registered in the database 26 can be obtained by acquiring the intensity pattern using a sample whose crystal orientation has been measured in advance by the EBSD method, the ECP method, or the like.

The measurement conditions when the intensity pattern is measured are also registered in the database 26. This is because the intensity distribution of diffracted electrons may change depending on the measurement conditions even in the same crystal orientation of the same sample. Therefore, when acquiring the intensity pattern of the sample S to be analyzed, it is preferable to perform the measurement under the same measurement conditions as those registered in the database 26.

The measurement conditions registered in the database 26 are conditions such as an acceleration voltage, an operating distance, and an incident angle of an electron beam, which affect the formation of an intensity pattern. If necessary, a plurality of measurement conditions and intensity patterns under the measurement conditions may be registered in the database 26.

Further, the intensity pattern of a desired crystal orientation may be obtained by simulation and registered in the database 26 as a reference intensity pattern.

Further, the database 26 may not be stored in the storage unit 24 before the measurement of the sample S to be analyzed. Intensity patterns of various crystal orientations may be obtained by simulation calculation from the measurement conditions of the sample S, and the intensity pattern may be used as a reference intensity pattern.

In this embodiment, the intensity patterns may be similar (that is, the Euclidean distance is small) even if the crystal orientations are different, depending on the number of detection regions, measurement conditions, crystallinity of the sample, and the like. Therefore, when it is determined that the analysis intensity pattern is similar to a plurality of reference intensity patterns, a process may be performed to notify the user that there are a plurality of crystal orientation candidates for the pixel.

In the above, the description of the electron detector 8 and the rotation of the crystal orientation is omitted, but in the actual analysis, the crystal orientation observed from the normal direction of the sample S is the same between the analysis position and the reference position. However, if the crystal orientation is rotated on the sample plane, the analysis intensity pattern and the reference intensity pattern do not match.

FIG. 18 is a diagram comparing the reference intensity pattern b and the analysis intensity pattern a when the crystal orientations are the same and the rotation angles of the crystal orientations are different. FIG. 19 is a diagram in which the reference intensity pattern b shown in FIG. 18 is rotated by 112.5 ° and compared with the analysis intensity pattern a. In FIGS. 18 and 19, the reference strength pattern b is shown by a broken line, and the analysis strength pattern a is shown by a solid line.

In FIG. 18, the reference intensity pattern b and the analysis intensity pattern a appear to be different. However, as shown in FIG. 19, when the reference intensity pattern b is rotated, the reference intensity pattern b and the analysis intensity pattern a match. Therefore, when specifying the crystal orientation, it is necessary to consider the rotation of the crystal orientation. Hereinafter, an analysis method considering the rotation of the crystal orientation will be described.

In considering the rotation of the crystal orientation, it is necessary to be able to obtain the same intensity pattern even if the sample S rotates, so that the plurality of detection regions 9 are arranged rotationally symmetrically about the optical axis OA. Since the electron beam travels along the optical axis OA, as shown in FIG. 2, the electron detector 8 has a circular shape with a through hole in the center of the detection surface. In addition, for example, the detection surface of the electron detector 8 may have a shape in which a polygon is equally divided in the circumferential direction. Further, as the electron detector 8 having a plurality of detection regions 9, a plurality of detectors having a single detection region may be prepared and arranged so as to be rotationally symmetric.

Further, when amplifying the detection signal, the respective amplification factors are matched. Similarly, if the zero points are deviated between the detection signals, the zero points are matched.

Here, the rotationally symmetric detection surface is rotated, and the minimum angle that matches the original detection surface is φd, and the difference in angle between the reference intensity pattern _b and the analysis intensity pattern a is _φp . When m = φ _p / φ _d and m is an integer or a value close to an integer (for example, φ _d ≈ φ _p , etc.), the reference intensity pattern and the analysis intensity pattern are rotated, so when analyzing the pattern. Consider the rotation of the pattern.

For example, considering the rotation of the intensity pattern, the Euclidean distance D can be obtained by the following equation (2).

When r = i + j ≦ n, r = i + j when r = i + j and i + j> n, and when j is changed from 1 to n, the intensity pattern rotates, so that pattern analysis can be performed in consideration of rotation. .. Here, the analysis intensity pattern is rotated, but the reference intensity pattern may be rotated. For example, the pattern analysis unit 33 first takes j = 1, calculates the Euclidean distance D, and if the value of D exceeds a predetermined value, increases j by 1 and calculates the Euclidean distance D again. This calculation is continued until j = 16. The pattern analysis unit 33 changes j between 1 and 16, and if the value of the Euclidean distance D is equal to or less than a predetermined value, the calculation is completed, and the pixel to be analyzed is the crystal orientation of the reference intensity pattern. If it is judged to be the same as the above and the value is not less than the predetermined value, the similarity of the patterns is evaluated using the minimum value of the Euclidean distance D in the range of 1 ≦ j ≦ 16.

When m is a decimal number, for example, if φ _d > φ _p , even if the analysis intensity pattern is rotated, it may not match the reference intensity pattern. This can occur especially when the number of detection areas 9 is small. For example, an electron beam is vertically incident on the sample S having a crystal orientation of 100, and the intensity distribution in the rotation direction of the diffracted electrons incident on the electron detector 8 above the sample S is symmetric four times. If this intensity distribution is acquired by an electron detector 8 having 16 detection regions 9, the result shown in FIG. 20 can be obtained in a certain direction. In the electron detector 8 having 16 detection regions 9, φ _d is 22.5 °. Therefore, when the intensity distribution of diffracted electrons when rotated by 11.25 ° is obtained, the result as shown in FIG. 21 is obtained. Will be.

Since this is a form in which the detection signal is integrated in the rotation direction, the signal amount varies greatly depending on the range of the intensity distribution to be detected when the angular width of the detection region 9 is larger than the amplitude of the intensity distribution in the rotation direction of the diffracted electrons. This is because it ends up.

In such a case, the intensity patterns of a plurality of rotation angles of the sample S may be registered in the database 26 as the reference intensity pattern.

For example, when the reference intensity pattern is acquired by the electronic detector 8 having 16 detection regions, the intensity pattern when the rotation angle of the sample S is 0 ° is the reference intensity pattern A, and the rotation angle of the sample S is the reference intensity pattern A. The intensity pattern at 11.25 ° is the reference intensity pattern B, the intensity pattern when the rotation angle of the sample S is 5.625 ° is the reference intensity pattern C, and the intensity when the rotation angle of the sample S is 16.875 °. The pattern is registered in the database 26 as the reference intensity pattern D. If the intensity pattern of the analysis position matches any of the reference intensity patterns A, B, C, and D, the crystal orientation of the analysis position matches the crystal orientation of the reference intensity patterns A, B, C, and D.

As described above, by registering a plurality of reference intensity patterns having different rotation angles for the same crystal orientation in the database 26, it is possible to specify the crystal orientation even when the rotation angles of the crystal orientations are different.

Further, in the above, the crystal orientation was analyzed by generating an intensity pattern while scanning the sample S with the electron probe, but it is not necessary to perform the scanning with the electron probe, and an electron beam is placed at one point on the sample S. It may be incident to generate an intensity pattern and analyze the crystal orientation.

2.2. Processing Next, the processing of the processing unit 30 of the electron microscope 200 will be described.

In the processing of the processing unit 30 of the electron microscope 100 described above, the intensity pattern in any pixel of the scanned image was used as the reference intensity pattern, but in the processing of the processing unit 30 of the electron microscope 200, the intensity pattern was stored in the database 26 as the reference intensity pattern. The difference is that the standard intensity pattern registered for each crystal orientation is used. Other points are the same as the processing of the processing unit 30 of the electron microscope 100 described above, and the description thereof will be omitted.

In the electron microscope 200, since the intensity pattern obtained in the known crystal orientation of the sample registered in the database 26 is used as the reference intensity pattern, it is determined in each pixel whether or not the intensity pattern is the same as the crystal orientation of the reference intensity pattern. be able to. Further, various crystal orientations can be specified by using a plurality of reference intensity patterns registered in the database 26 having different crystal orientations from each other.

In the electron microscope 200, the crystal orientation thus specified may be displayed on the crystal orientation image.

2.3. Process flow Next, the process flow of the processing unit 30 of the electron microscope 200 according to the second embodiment will be described. FIG. 22 is a flowchart showing an example of the processing flow of the processing unit 30 of the electron microscope 200 according to the second embodiment. Hereinafter, the points different from the processing of the processing unit 30 of the electron microscope 100 shown in FIG. 16 described above will be described, and detailed description of the same points will be omitted.

The intensity pattern information generation unit 32 generates an intensity pattern based on the intensity of the first to nth detection signals (S200).

This process S200 is performed in the same manner as the above-mentioned process S100.

Next, the pattern analysis unit 33 generates an arbitrary pixel of the scanned image as (x, y), the intensity pattern in the pixel as ax _{, y} , and ax, _y as a reference intensity pattern registered in the database 26. The crystal orientations are specified by comparing the strength patterns obtained (S202).

Specifically, the Euclidean distance from the reference intensity pattern b registered in the database 26 is calculated, and when the Euclidean distance is smaller than a predetermined value, the crystal orientation in the pixel is the same as the crystal orientation of the reference intensity pattern. Judge.

The pattern analysis unit 33 may perform a process of specifying the crystal orientation by using a plurality of reference intensity patterns having different crystal orientations. Specifically, the m reference strength patterns registered in the database 26 are b1, b2, ..., Bm, and the strength patterns ax _{, y} and the reference strength patterns b1, b2, ..., Bm. Let the Euclidean distance be D1, D2, ..., Dm.

First, the pattern analysis unit 33 calculates the Euclidean distance D1 of the intensity patterns ax _{and y} and the reference intensity pattern b1. Similarly, the Euclidean distances D2, ..., Dm with the registered reference strength patterns b2, ..., Bm are calculated, and the Euclidean distances D1, ..., Dm obtained are larger than the predetermined values. A small Euclidean distance is extracted, it is determined that the crystal orientation at that position is the same as the crystal orientation of the reference intensity pattern, and the orientation information associated with the reference intensity pattern is output. Further, the pattern analysis unit 33 may perform a process of specifying the crystal orientation by using a plurality of reference intensity patterns having different rotation angles.

Next, the image generation unit 34 generates a crystal orientation image based on the orientation information generated by the pattern analysis unit 33 (S204). The image generation unit 34 determines pixel information such as color and brightness corresponding to the crystal orientation based on the orientation information generated by the pattern analysis unit 33, and generates an image.

The image generation unit 34 controls to display the generated image on the display unit 22 (S206). At this time, the image generation unit 34 may display, for example, information on the crystal orientation specified on the generated image.

2.4. Features The electron microscope 200 has the following features, for example.

In the electron microscope 200, the pattern analysis unit 33 acquires the reference intensity pattern information from the database 26 in which the reference intensity pattern is registered for each crystal orientation. Therefore, in the electron microscope 200, the crystal orientation can be easily specified.

In the electron microscope 200, the pattern analysis unit 33 compares the reference intensity pattern registered in the database 26 with the generated intensity pattern to specify the crystal orientation, and the image generation unit 34 crystallizes based on the specified crystal orientation. Generate an orientation image. Therefore, in the electron microscope 200, the crystal orientation of the crystal grains can be easily specified.

2.5. Modification Example Next, a modification of the electron microscope 200 according to the second embodiment will be described.

In the above-described embodiment, the crystal orientation is specified by using the reference intensity pattern of the known crystal orientation registered in the database 26, but the method for specifying the crystal orientation is not limited to this.

For example, in 100 cubic orientations, the intensity distribution of diffracted electrons is 4-fold symmetric, and in other crystal orientations, the intensity distribution of diffracted electrons is not 4-fold symmetric. Therefore, if the intensity pattern has four-fold symmetry, it can be determined that the orientation is 100. Hereinafter, a specific description will be given.

The image generation unit 34 analyzes the periodicity of the analysis intensity pattern by performing an FFT (fast Fourier transform) on the acquired analysis intensity pattern. For example, if it can be determined that the crystal orientation has four-fold symmetry as a result of analysis, it can be specified that the crystal orientation is 100 orientations.

In the electron microscope 200, for example, while scanning the sample S with an electron probe, the crystal orientation is specified from the analysis intensity pattern generated by the intensity pattern information generation unit 32. At this time, the image generation unit 34 performs a process of emphasizing and displaying the pixels whose crystal orientation can be specified. Analysis The identification of the crystal orientation by the periodicity of the intensity pattern can only analyze the orientation characteristic of the intensity pattern. However, this method can analyze the crystal orientation quickly and easily, and it is not necessary to prepare a database or the like in advance.

In the above, the intensity pattern was acquired and the crystal orientation was specified while scanning the sample S with the electron probe. However, the electron beam was irradiated to one point on the sample S to acquire the intensity pattern and the crystal orientation was specified. May be good.

In this modification, the pattern analysis unit 33 specifies the crystal orientation of the sample S based on the symmetry of the intensity pattern. Therefore, the crystal orientation of the sample S can be easily specified.

3. 3. Third Embodiment 3.1. Electron Microscope Next, the electron microscope according to the third embodiment will be described with reference to the drawings. FIG. 23 is a diagram showing the configuration of the electron microscope 300 according to the third embodiment. Hereinafter, in the electron microscope 300 according to the third embodiment, the members having the same functions as the constituent members of the electron microscope 100 according to the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

In the second embodiment described above, the crystal orientation is specified using the reference intensity pattern of the known crystal orientation registered in the database 26.

On the other hand, in the third embodiment, the crystal orientation is specified by measuring the crystal orientation by the EBSD method.

The electron microscope 300 includes an EBSD detector 302 as shown in FIG. Further, in the electron microscope 300, the processing unit 30 includes the control unit 36.

In the electron microscope 300, an electron beam is incident on the surface of the sample S from a direction of about 70 °. The electrons incident on the sample S are diffracted and emitted from the sample S as reflected electrons. The diffraction pattern (EBSD pattern) that appears at this time is projected on the EBSD detector 302, and this diffraction pattern is acquired by the EBSD detector 302. The acquired diffraction pattern information is sent to the processing unit 30.

As described above, when the diffraction pattern is acquired by the EBSD detector 302, the sample S is greatly tilted with respect to the optical axis OA. On the other hand, when the electron detector 8 detects the reflected electrons, the sample S is placed horizontally and the measurement is performed in the same state as in the first embodiment (see FIG. 1).

The measurement may be performed by the electron detector 8 in a state where the sample S is greatly tilted with respect to the optical axis OA. In this case, it may be difficult for the electrons emitted from the sample S to reach directly under the objective lens 4. Therefore, the electron detector 8 may be arranged at a position where the electrons emitted from the sample S can easily reach.

Further, in this configuration, the EBSD detector 302 may be substituted as the electronic detector 8. Specifically, a two-dimensional array type detector is usually used as the EBSD detector, and a signal is captured as an image. The captured image is divided into a plurality of areas, the brightness in the areas is integrated to obtain a signal amount, and an intensity pattern is generated using the signal amount for each area.

The control unit 36 performs a process of controlling the optical system of the electron microscope 300 and the like. For example, the measurement by the EBSD method is automatically performed by the processing of the control unit 36.

3.2. Processing Next, the processing of the processing unit 30 of the electron microscope 300 will be described. In the electron microscope 300, the crystal orientation in the pixels constituting the pattern analysis image is specified based on the diffraction pattern acquired by the EBSD detector 302. At this time, the pattern analysis unit 33 compares and groups the intensity pattern and the reference intensity pattern in each pixel constituting the pattern analysis image, acquires a diffraction pattern for each group, and crystallizes the crystal corresponding to the group. Identify the orientation. Hereinafter, this process will be specifically described. Hereinafter, the points different from the processing of the electron microscope 100 described above will be described, and the same points will be omitted.

In the electron microscope 300, the emitted backscattered electrons are detected by the electron detector 8 while scanning on the sample S with the electron probe as in the first embodiment described above, and the signal intensity sequence s (x, y, z) is detected. ) Is obtained. Then, the intensity pattern information generation unit 32 generates an intensity pattern for each pixel constituting the scanned image. The storage unit 24 stores the intensity pattern corresponding to each of the plurality of pixels constituting the scanned image.

For example, the pattern analysis unit 33 uses an intensity pattern in any pixel as a reference intensity pattern, and obtains the Euclidean distance between the intensity pattern of the pixel and the reference intensity pattern in all the pixels constituting the scanning image. Then, the pixels whose Euclidean distance is equal to or less than a predetermined value are set as the set G1, and the set G = G1.

Next, an arbitrary pixel other than the set G is selected, and the Euclidean distance is obtained in the pixels other than the set G, using the intensity pattern in the selected pixel as the reference intensity pattern. Then, the pixels whose Euclidean distance is equal to or less than a predetermined value are set as the set G2, and the set G = G∪G2.

Further, an arbitrary pixel other than the set G is selected, and the Euclidean distance is obtained by using the intensity pattern in the selected pixel as a reference intensity pattern. Then, the pixels whose Euclidean distance is equal to or less than a predetermined value are set as the set G3, and G = G∪G3.

In this way, if a set of pixels with similar intensity patterns is added to the set G, and finally all the pixels belong to G, and there are m sets of the obtained sets, then G1, G2, ..., A set of Gm is created.

In the above, the intensity pattern in the pixels other than the set G is used as the reference intensity pattern, and the process of finding the Euclidean distance and grouping the pixels other than the set G is repeated. On the other hand, the process of finding the Euclidean distance and grouping all the pixels constituting the scanned image may be repeated by using the intensity pattern in the pixels other than the set G as the reference intensity pattern.

Here, depending on the accuracy of the pattern analysis and the variation in the intensity distribution of the diffracted electrons, pixels belonging to a plurality of sets may be formed. In this case, any one of the pixels belonging to a plurality of sets
Belong to one set and not to multiple sets. That is, 0 = G1∩G2∩ ... ∩Gm. For example, when there is a pixel belonging to a plurality of sets, the set of the pixels may be determined from the set to which the pixels around the pixel belong. For example, the pixel may belong to the set to which the surrounding pixels belong most, or may belong to the set having the smallest Euclidean distance.

The pattern analysis unit 33 acquires a diffraction pattern for each of the obtained sets G1, G2, ..., Gm and specifies the crystal orientation. Specifically, the pattern analysis unit 33 first identifies a region on the sample S corresponding to the pixels belonging to the set G1 and determines a measurement position within the region. It should be noted that the measurement position may be one point or a plurality of points for one set.

Then, the control unit 36 controls the optical system of the electron microscope 100 so that the diffraction pattern at the position can be obtained based on the information of the measurement position. As a result, the diffraction pattern at the measurement position can be acquired by the EBSD detector 302. Then, the pattern analysis unit 33 specifies the crystal orientation of the set G1 from the obtained diffraction pattern. The same processing is performed for the other sets G2, ..., Gm. As a result, the crystal orientation can be specified for all the pixels constituting the pattern analysis image.

The image generation unit 34 generates a crystal orientation image in which each pixel is set to the color and brightness corresponding to the orientation based on the obtained crystal orientation information.

In this embodiment, the pattern analysis process is the same as that of the first embodiment described above, and the description thereof will be omitted.

Here, in the EBSD method, an electron beam is incident on the sample surface from an oblique direction with an electron beam having a high acceleration voltage to obtain a diffraction pattern, so that the electron scattering region in the sample S becomes large. Therefore, the resolution is about several tens of nm, and it is difficult to analyze crystal grains having a particle size smaller than this.

On the other hand, in the electron microscope 300, since electrons having a low acceleration voltage are incident on the sample surface from the direction perpendicular to the sample surface, the electron scattering region is smaller than that measured by the EBSD method. Therefore, the resolution is about several nm. Therefore, with the electron microscope 300, it is possible to analyze the crystal orientation of crystal grains having a particle size of about several nm, which is lower than the resolution of the EBSD method.

Specifically, the image generation unit 34 generates a pattern analysis image, and the crystal orientation map is acquired by the EBSD method. Then, the crystal orientation map acquired by the EBSD method is associated with the pattern analysis image to specify the crystal orientation of the pattern analysis image. At this time, among the crystal grains included in the pattern analysis image, the crystal orientation cannot be specified for the crystal grains having a resolution lower than the resolution of the EBSD method.

Therefore, among the crystal grains included in the pattern analysis image, the crystal grains whose crystal orientation cannot be specified by the EBSD method or lower than the resolution of the EBSD method are based on the strength pattern of the crystal grains whose crystal orientation is specified by the EBSD method. To specify the crystal orientation of the crystal grains.

Specifically, a database in which the crystal orientation specified by the EBSD method and the intensity pattern are associated with each other is created from the pattern analysis image and the crystal orientation map by the EBSD method. Then, for the intensity pattern of the crystal grains whose crystal orientation could not be specified by the EBSD method, the euclidean distance from the intensity pattern registered in the database is calculated, and the crystal orientation corresponding to the intensity pattern having the smallest euclidean distance is determined by the crystal. The crystal orientation of the grain.

As a result, the orientation of the crystal grains in the pattern analysis image is specified, and the image generation unit 34 generates a crystal orientation image based on the analysis result.

3.3. Process flow Next, the process flow of the processing unit 30 of the electron microscope 300 according to the third embodiment will be described. FIG. 24 is a flowchart showing an example of the processing flow of the processing unit 30 of the electron microscope 300 according to the third embodiment. Hereinafter, the points different from the processing of the processing unit 30 of the electron microscope 100 shown in FIG. 16 described above will be described, and detailed description of the same points will be omitted.

The intensity pattern information generation unit 32 generates an intensity pattern based on the intensity of the first to nth detection signals (S300).

This process S300 is performed in the same manner as the above-mentioned process S100.

Next, the pattern analysis unit 33 performs pattern analysis based on the intensity pattern stored in the storage unit 24 to generate pattern analysis information (S302), and the image generation unit 34 performs pattern analysis based on the pattern analysis information. Generate an image (S304).

Next, the pattern analysis unit 33 identifies the crystal orientation of the crystal grains contained in the pattern analysis image based on the analysis result of the crystal orientation by the EBSD method (S306).

At this time, for example, in each pixel constituting the crystal orientation image, the pattern analysis unit 33 compares and groups the intensity pattern and the reference intensity pattern in the pixel, and acquires the diffraction pattern by the EBSD method for each group (set). Then, the crystal orientation corresponding to the group may be specified.

Further, the pattern analysis unit 33 may specify the crystal orientation of the crystal grains included in the pattern analysis image, for example, based on the analysis result of the crystal orientation by the crystal orientation map by the EBSD method. Then, among the crystal grains in the pattern analysis image, the crystal orientation of the crystal grain whose crystal orientation could not be specified by the crystal orientation map is specified based on the strength pattern of the crystal grain whose crystal orientation is specified by the crystal orientation map. May be good.

Next, the image generation unit 34 generates a crystal orientation image in which each pixel is represented by the corresponding brightness and color based on the specified crystal orientation (S308).

Next, the image generation unit 34 controls the display unit 22 to display the generated crystal orientation image and the specified crystal orientation information (S310).

3.4. Features The electron microscope 300 has the following features, for example.

The electron microscope 300 includes an EBSD detector 302 that acquires a diffraction pattern (EBSD pattern) obtained by irradiating the sample S with an electron beam, and the pattern analysis unit 33 captures a pattern analysis image based on the diffraction pattern. Specify the crystal orientation in the constituent pixels. Therefore, in the electron microscope 300, the crystal orientation in the pixels constituting the pattern analysis image can be specified.

In the electron microscope 300, the pattern analysis unit 33 compares and groups the intensity pattern of the pixel and the reference intensity pattern in the pixels constituting the pattern analysis image, acquires the diffraction pattern by the EBSD method for each group, and sets the group. Identify the crystal orientation. Therefore, in the electron microscope 300, the number of points of analysis by the EBSD method can be reduced as compared with the case where the crystal orientation map is acquired by the EBSD method, for example.

In the electron microscope 300, the pattern analysis unit 33 identifies the crystal orientation of the crystal grains included in the pattern analysis image based on the diffraction pattern (for example, the crystal orientation map by the EBSD method), and diffracts among the crystal grains of the pattern analysis image. The crystal orientation of the crystal grain whose crystal orientation could not be specified based on the pattern is specified based on the intensity pattern of the crystal grain whose crystal orientation is specified based on the diffraction pattern. Therefore, in the electron microscope 300, for example, it is possible to specify the crystal orientation of the crystal grains below the resolution of the EBSD method.

In the above, the case of specifying the crystal orientation of the crystal grains contained in the pattern analysis image from the analysis result based on the diffraction pattern by the EBSD method has been described, but the method of specifying the crystal orientation is not particularly limited, and the ECP method is used. The crystal orientation of the crystal grains contained in the pattern analysis image may be specified from the analysis result based on the diffraction pattern by.

4. Fourth Embodiment 4.1. Electron Microscope Next, the electron microscope according to the fourth embodiment will be described with reference to the drawings. FIG. 25 is a diagram showing the configuration of the electron microscope 400 according to the fourth embodiment. Hereinafter, in the electron microscope 400 according to the fourth embodiment, the members having the same functions as the constituent members of the electron microscope 100 according to the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 25, the electron microscope 400 is provided with a sample loading unit 402 capable of applying a load to the sample S.

The sample load applying unit 402 has, for example, a mechanism for applying a force to the sample S to deform it. Further, the sample load applying unit 402 has, for example, a mechanism for applying heat to the sample S.

Since the electron microscope 400 includes the sample loading unit 402, it is possible to acquire an image while applying a force to the sample S to deform it, or to acquire an image while applying heat to the sample S.

4.2. Processing Next, the processing of the processing unit 30 of the electron microscope 400 will be described. In the first embodiment described above, an intensity pattern in a plurality of pixels constituting a scanned image was obtained by scanning one electron probe. Then, in each pixel, the intensity pattern of the pixel and the reference intensity pattern were compared, the brightness of each pixel was calculated from the similarity, and a pattern analysis image was generated.

Here, the electron microscope is also used, for example, to observe the shape and growth of the crystal grains of the sample S while applying a force to deform the sample S or applying heat. In this case, while applying a load such as heat or stress to the sample S, scanning with an electron probe is repeated to acquire a plurality of continuous scanning images. As a result, it is possible to observe how the shape of the crystal grains changes depending on the load applied to the sample S.

If the above-mentioned method for generating a crystal orientation image is applied to this observation method, changes in the shape of crystal grains and crystal orientation can be observed more easily and easily.

At this time, in the electron microscope 400, when scanning with the electron probe is repeated, the reference intensity pattern is common, that is, the same intensity pattern is used. For example, when scanning with an electronic probe is repeated and the reference intensity pattern is not common, the same intensity pattern is used in the crystal orientation image obtained in the first scan and the crystal orientation image obtained in the second scan. Even if there is a pixel for which is obtained, the brightness of the pixel will be different.

For example, when the reference intensity pattern is an intensity pattern in an arbitrary pixel (for example, a pixel located in the center of the field of view) of the scanning image obtained by one scanning, the crystal grains corresponding to the pixel are obtained by repeating the scanning. Is distorted or the crystal orientation changes, and the reference intensity pattern changes. Therefore, in the electron microscope 400, the reference intensity pattern is common when scanning with the electron probe is repeated. Hereinafter, this method will be specifically described. Further, in the following, points different from the above-mentioned processing of the electron microscope 100 will be described, and description of the same points will be omitted.

There are two possible timings for setting the reference intensity pattern: before the load is applied to the sample S (before the load test) and after the load is applied to the sample S (after the load test).

First, a case where a reference strength pattern is set before the load test will be described. By setting the reference intensity pattern before applying the load to the sample S, it is possible to confirm the change in the state of the sample S in real time while applying the load to the sample S. For example, it is effective when the sample S whose crystal orientation is known in advance by the EBSD method or the like is to pay attention to a certain orientation and to see the change when a load is applied.

Before the load test, the data for one scan is acquired. That is, the intensity pattern in all the pixels constituting the scan image for one scan is acquired. The reference strength pattern is acquired from the acquired strength pattern data. As the reference intensity pattern, the intensity pattern in any pixel (for example, the pixel in the center of the field of view) may be automatically selected, or a scan image is generated from the acquired intensity pattern data and scanned by the user. It may be possible to select a pixel to acquire a reference intensity pattern from the image.

Further, when it is desired to pay attention to the change in a specific crystal orientation and the intensity pattern in the crystal orientation is known in advance, the intensity pattern may be used as a reference intensity pattern.

Further, the intensity pattern in an arbitrary pixel is acquired and used as a temporary reference intensity pattern, and a temporary pattern analysis image is generated using the temporary reference intensity pattern to make it easier to observe the crystal grains, and then the provisional reference intensity pattern is obtained. Pixels that obtain a reference intensity pattern from the pattern analysis image may be specified.

The set reference intensity pattern is stored in the storage unit 24. A plurality of reference strength patterns may be set.

Next, a load is applied to the sample S, and while scanning on the sample S with an electron probe, electrons are detected in a plurality of detection regions 9. Then, the pattern analysis unit 33 compares the determined reference intensity pattern with the intensity pattern based on the intensity of the first to nth detection signals in each pixel constituting the scanned image, and the image generation unit 34 is the pattern analysis unit. A pattern analysis image is generated based on the analysis result in 33. The image generation unit 34 associates the pattern analysis image generated in the first scan after the load is applied to the sample S, the pattern analysis image generated in the second scan, ..., With the information of the number of scans, respectively. The process of storing the image in the storage unit 24 is performed.

As a result, from the obtained plurality of pattern analysis images, it is possible to observe how the shape and crystal orientation of the crystal grains of interest change depending on the load applied to the sample S.

Further, by performing these processes while performing a load test and displaying the latest pattern analysis image obtained on the display unit 22, the state of the crystal grains of the sample can be observed, and the strength of the load is changed accordingly. You can also use it like this.

Next, a case where the reference strength pattern is determined after the load test will be described.

The load test is started while scanning on the sample S with an electron probe, and electrons are detected in a plurality of detection regions 9. Then, the data of the signal amount of the first and second detection signals associated with the incident position of the electron beam (hereinafter, also referred to as "scan data") obtained in the first scan, was obtained in the second scan. The scan data, ... Is stored in the storage unit 24 in association with the information on the number of scans. At this time, the display unit 22 may display a scanned image based on the total intensity of the first to nth detection signals.

As the number of scans increases, the amount of data increases, so the scan data may be compressed and converted.

After the load test, the pattern analysis unit 33 can read scan data from the storage unit 24 for analysis, and the image generation unit 34 can sequentially generate a pattern analysis image and display it on the display unit 22.

In this way, a pattern analysis image can be generated and displayed for each scan with the electronic probe based on the scan data stored in the storage unit 24. At this time, if there is a crystal grain that the user is interested in, by designating the crystal grain, the strength pattern of the crystal grain at that time becomes the reference strength pattern. This makes it possible to observe changes in crystal grains specified by the user.

By combining these two methods, a reference intensity pattern is set before the load test, scan data is recorded while generating a pattern analysis image in real time, and a reference intensity pattern is set again after the load test for pattern analysis. An image can be generated and displayed on the display unit 22.

Further, the intensity pattern associated with the crystal orientation may be used as the reference intensity pattern, the crystal orientation may be specified from the analysis result obtained by the pattern analysis unit 33, and the crystal orientation image may be generated by the image generation unit 34.

4.3. Features The electron microscope 400 has the following features, for example.

In the electron microscope 400, the image generation unit 34 generates a plurality of pattern analysis images in response to a plurality of scans of the sample S by the electron probe, and the reference intensity pattern is common to the plurality of pattern analysis images. Therefore, with the electron microscope 400, as described above, the change in the crystallinity of the sample S can be observed.

For example, in the electron microscope 400, the state of the phase transition of the sample S can be observed by repeatedly scanning with the electron probe while applying heat to the sample S to acquire a plurality of pattern analysis images. Further, by monitoring the temperature of the sample S, the temperature of the phase transition can be specified.

5. Fifth Embodiment 5.1. Electron Microscope Next, the electron microscope according to the fifth embodiment will be described with reference to the drawings. FIG. 26 is a diagram showing the configuration of the electron microscope 500 according to the fifth embodiment. FIG. 27 is a plan view schematically showing the electron detector 508.

Hereinafter, in the electron microscope 500 according to the fifth embodiment, the members having the same functions as the constituent members of the electron microscope 100 according to the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

In the electron microscope 500, as shown in FIG. 27, the electron detector 508 has a configuration in which n'detection regions 509 (an example of a detection unit) are arranged in a line. However, n'is an integer of 2 or more.

The intensity pattern information generation unit 32 shown in FIG. 26 generates an intensity line profile as intensity pattern information based on the intensity of n'detection signals output from the n'intensity detection regions 509. The processing unit 30 includes a line profile analysis unit 38 that specifies the crystal orientation based on the intensity line profile generated by the intensity pattern information generation unit 32.

As shown in FIG. 27, the electron detector 508 is a split detector having n'detection regions 509. The n'detection regions 509 are arranged along a circle in the illustrated example. The detection region 509 can independently detect electrons as in the detection region 9 shown in FIG. 2 described above. The detection regions 509 are arranged in the number in which the line profile of the diffraction pattern described later can be obtained.

In the electron microscope 500, the area of one detection region 509 is smaller than the area of the detection region 9 of the electron detector 8 shown in FIG. The area of one detection area 9 shown in FIG. 2 is larger than the width of the Kikuchi line formed on the surface on which the electron detector 508 is arranged, for example, but the area of one detection area 509 shown in FIG. 27 is large. It is smaller than the width of the Kikuchi line. The area of one detection area 509 is preferably sufficiently smaller than the width of the Kikuchi line so that the Kikuchi line can be identified.

The electron detector 508 is configured to include, for example, n'photodiodes arranged along a circle. The n'photodiodes correspond to the n'detection regions 509. The electron detector 508 may be one in which optical fibers coated with a fluorescent paint at the tip are arranged along a circle and a photodetector is connected to the rear end. As the photodetector, a photodiode, a photomultiplier tube, or the like can be used.

FIG. 28 is a diagram showing the relationship between the diffraction pattern formed on the surface on which the electron detector 508 (detection region 509) is arranged and the electron detector 508. In FIG. 28, for convenience, n'detection regions 509 are represented by lines. The line formed by n'detection areas 509 is also referred to as a detection line.

As shown in FIG. 28, the electrons incident on the sample S are scattered in the sample S and then diffracted by the lattice plane of the crystal. The diffracted electrons (reflected electrons) are emitted from the sample S, and a diffraction pattern is formed on the surface on which the electron detector 8 is arranged. Here, the Kikuchi pattern is generated by causing Bragg reflection (elastic scattering) after the electrons incident on the sample S are inelastically scattered by the thermal vibration of atoms in the crystalline sample. Since the traveling direction of the electron subjected to inelastic scattering is distributed over a wide angle, a pair of bright and dark lines due to the reflection of the front surface and the back surface of a certain crystal plane is generated at the Bragg reflection position. This pair of bright and dark lines is called the Kikuchi line.

As shown in FIG. 28, the n'detection regions 509 are line-shaped and are configured to cross a plurality of Kikuchi lines. Therefore, it is possible to acquire a line profile (hereinafter, also referred to as “intensity line profile”) along the line in which the n ′ detection regions 509 are arranged by the n ′ detection regions 509. The intensity line profile represents the luminance on the detection line (intensity of the Kikuchi line).

5.2. Processing Next, the processing of the processing unit 30 of the electron microscope 500 will be described. In the electron microscope 500, the intensity pattern information generation unit 32 generates an intensity line profile as intensity pattern information based on the intensity of n'detection signals output from the n'intensity detection regions 509. The line profile analysis unit 38 specifies the crystal orientation based on the intensity line profile. Hereinafter, the points different from the processing of the electron microscope 100 described above will be described, and the same points will be omitted.

5.2.1. Generation of line profile The intensity pattern information generation unit 32 generates an intensity line profile as intensity pattern information based on the intensities of n'detection signals output from n'investment regions 509.

The intensity line profile to be analyzed is emitted from the sample S by irradiating the point where the crystal orientation on the sample S is analyzed (hereinafter, also referred to as “analysis point”) with an electron beam, and being scattered and diffracted by the sample S. It can be acquired by detecting the generated electrons with the electron detector 508.

FIG. 29 is a diagram showing an example of an intensity line profile.

In the intensity line profile, the horizontal axis represents the position on the diffraction pattern, and the vertical axis represents the intensity (that is, the brightness) of the diffraction pattern. In the illustrated example, since the n'detection regions 509 are arranged along the circle, the intensity line profile is the intensity profile along the circle on the diffraction pattern. The area of one detection area 509 is sufficiently small with respect to the width of the Kikuchi line. Therefore, in the intensity line profile, the peak corresponding to the bright line of the Kikuchi line and the bottom corresponding to the dark line can be seen.

5.2.2. Generation of reference line profile The line profile analysis unit 38 obtains the diffraction pattern of the sample S by calculation (simulation), and generates a line profile (hereinafter, also referred to as “reference line profile”) from the obtained diffraction pattern. In the fifth embodiment, the crystal orientation is obtained by comparing the intensity line profile obtained by using n'detection regions 509 with the line profile (reference line profile) generated from the diffraction pattern obtained by the simulation. To identify.

The diffraction pattern can be obtained by simulation. Specifically, the diffraction pattern can be calculated by using a known method from, for example, the elements constituting the crystal, the crystal structure thereof, and the energy of the electrons incident on the sample S.

In order to generate a reference line profile from the diffraction pattern obtained by the simulation, for example, the shape and position of the detection line may be known.

The shape and position of the detection line can be known from the shape and position of the n'detection regions 509 and the distance between the surface on which the n'detection regions 509 are arranged and the sample S. This information can be obtained from the design information of the device. Therefore, in the electron microscope 500, these information are stored in the storage unit 24 in advance.

30 and 31 are diagrams for explaining a method for obtaining a reference line profile.

For example, as shown in FIG. 30, when the electron detector 508 having the radius e is arranged under the objective lens 4 and the distance between the objective lens 4 and the electron detector 508 is at the position f, the working distance. Is g, the distance between the sample S and the electron detector 508 is the distance g−f. Therefore, the electron detector 508 has acquired the signal on the angle θ = tan ^-1 (e / (g−f)) line on the diffraction pattern. Therefore, a reference line profile can be generated by acquiring a profile on a line satisfying this angle θ from the diffraction pattern obtained by the simulation.

Diffraction patterns are calculated at various crystal orientations and a reference line profile is generated for each. The crystal orientation and the reference line profile are associated and stored in the storage unit 24. In this way, a database of crystal orientations and reference line profiles of the sample to be analyzed can be generated.

Since the diffraction pattern changes depending on the measurement conditions, the diffraction pattern may be calculated in advance under various measurement conditions to create a database, and the database according to the measurement conditions may be read out and used.

5.2.2. The analysis line profile analysis unit 38 compares the intensity line profile generated by the intensity pattern information generation unit 32 with the reference line profile to specify the crystal orientation.

The intensity line profile generated by the intensity pattern information generation unit 32 is compared with the reference line profile of the database, and the crystal orientation associated with the reference line profile having the closest profile shape is the crystal orientation of the analysis point.

The comparison between the intensity line profile at the analysis point and the reference line profile of the database can be performed, for example, by calculation using the Euclidean distance. The Euclidean distance between the intensity line profile and the reference line profile can be obtained by the same calculation (see equation (1) or equation (2)) as in the case of obtaining the Euclidean distance D of the intensity pattern described above.

The comparison between the intensity line profile and the reference line profile is not limited to the method using the Euclidean distance. For example, the position and width of the Kikuchi line in the diffraction pattern obtained by the simulation may be registered in the database, the position and width of the Kikuchi line may be estimated from the intensity line profile, and the comparison may be performed by searching the database. .. According to this method, it is not necessary to obtain the intensity of the diffraction pattern by simulation, so that the database can be created more easily.

The analysis result of the crystal orientation at the analysis point obtained in this way is displayed on the display unit 22.

5.3. Process flow Next, the process flow of the processing unit 30 of the electron microscope 500 according to the fifth embodiment will be described. FIG. 32 is a flowchart showing an example of the processing flow of the processing unit 30 of the electron microscope 500 according to the fifth embodiment. Hereinafter, the points different from the processing of the processing unit 30 of the electron microscope 100 shown in FIG. 16 described above will be described, and detailed description of the same points will be omitted.

First, the line profile analysis unit 38 generates a database of crystal orientations and reference line profiles of the sample to be analyzed (S400). When the user inputs the composition of the sample to be analyzed and its crystal structure via the operation unit 20, the line profile analysis unit 38 generates and generates reference line profiles of various crystal orientations in the sample to be analyzed. The reference line profile created is registered in the database in association with the crystal orientation. The database is stored in the storage unit 24.

Next, the intensity pattern information generation unit 32 generates an intensity line profile at the analysis point based on the intensity of the n'detection signals output from the n'detection regions 509 (S402).

Next, the line profile analysis unit 38 compares the intensity line profile at the analysis point with the reference line profile to specify the crystal orientation (S404).

The image generation unit 34 controls the display unit 22 to display the specified crystal orientation information (S406).

5.4. Features The electron microscope 500 has, for example, the following features.

In the electron microscope 500, the intensity pattern information generation unit 32 generates an intensity line profile based on the intensities of a plurality of detection signals output from the plurality of detection regions 509. Therefore, in the electron microscope 500, the crystallinity information of the sample S can be easily obtained as in the electron microscope 100 described above.

Further, in the electron microscope 500, since the measurement can be performed by detecting the backscattered electrons by the electron detector 508 provided with the plurality of detection regions 509, the measurement can be performed in a shorter time than the measurement by the EBSD method or the ECP method, for example. Is possible.

In the electron microscope 500, the line profile analysis unit 38 identifies the crystal orientation based on the intensity line profile. Therefore, information on the crystallinity of the sample S can be easily obtained.

In the electron microscope 500, the line profile analysis unit 38 obtains a diffraction pattern obtained by irradiating the sample S with an electron beam by calculation, generates a reference line profile as a reference from the obtained diffraction pattern, and sets the intensity line profile. , Identify the crystal orientation by comparing with the reference line profile. Therefore, information on the crystallinity of the sample S can be easily obtained.

5.5. Modification Example Next, a modification of the electron microscope 500 according to the fifth embodiment will be described.

5.5.1. First Modification Example FIGS. 33 and 34 are diagrams for explaining a modification of the electron detector 508. 33 and 34 correspond to FIG. 28.

For example, in the above-mentioned electron detector 508, as shown in FIGS. 27 and 28, the case where n'detection regions 509 are arranged along a circle and the detection line is a circle has been described. As shown in FIG. 33, n'detection regions 509 may be arranged along a polygon (triangle in the illustrated example), and the detection line may be a polygon. Further, as shown in FIG. 34, the detection lines by the n'detection regions 509 do not have to be a closed curve. In the electron detector 508 shown in FIG. 34, n'detection regions 509 are arranged along two parallel lines and a line connecting the ends of the two lines, and the detection lines are these lines. It is the shape to be formed.

When the detection line shown in FIG. 28 is a circle, the Euclidean distance can be obtained by using the equation (2) even when the intensity line profile is rotated. However, in the detection lines shown in FIGS. 33 and 34, the Euclidean distance cannot be obtained using the equation (2). Therefore, line profiles with various rotation angles are registered in the database in advance.

5.5.2. 2nd Modification Example FIG. 35 is a diagram for explaining a modification of the electron detector 508.

For example, the electron detector 508 shown in FIG. 27 described above includes n'detection regions 509, but the electron detector 508 shown in FIG. 35 has one detection region 509 and a detection region 509. It is configured to include a moving mechanism 510 for moving the moving mechanism 510.

The moving mechanism 510 moves the detection region 509 along a circle in the illustrated example. By detecting the reflected electrons in the detection region 509 while changing the position of the detection region 509 by the moving mechanism 510, the same intensity line profile as the electron detector 508 shown in FIG. 27 can be obtained. The intensity pattern information generation unit 32 generates an intensity line profile based on, for example, the position of the detection region 509 and the intensity of the detection signal at that position.

The moving mechanism 510 may move the detection region 509 along the detection line shown in FIG. 33 and the detection line shown in FIG. 34.

5.5.3. Third Modification Example In the fifth embodiment described above, the case of analyzing the crystal orientation at the analysis point has been described, but by moving the analysis point, the sample is similar to the electron microscope 100 according to the first embodiment described above. It is also possible to generate a crystal orientation image showing the distribution of the crystal orientation of S. In this case, since the information and measurement conditions of the sample S are the same, the crystal orientation can be analyzed using the same database at all the analysis points.

6. Sixth Embodiment 6.1. Electron Microscope Next, the electron microscope according to the sixth embodiment will be described with reference to the drawings. FIG. 36 is a diagram showing the configuration of the electron microscope 600 according to the sixth embodiment. Hereinafter, in the electron microscope 600 according to the sixth embodiment, the members having the same functions as the constituent members of the electron microscope 500 according to the fifth embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 36, the electron microscope 600 includes an X-ray detector 602 and a signal processing unit 604. Further, in the electron microscope 600, the processing unit 30 includes an elemental analysis unit 39.

In the electron microscope 500 shown in FIG. 26 described above, the user inputs the composition information of the sample S, but in the electron microscope 600, the composition information of the sample S to be analyzed is acquired from the result of the elemental analysis by the X-ray detector 602. do.

The X-ray detector 602 is, for example, an energy dispersion X-ray detector, a wavelength dispersion X-ray detector, or the like. The signal output from the X-ray detector 602 is sent to the signal processing unit 604. The signal processing unit 604 generates spectral data based on the signal from the X-ray detector 602 and sends it to the processing unit 30. The elemental analysis unit 39 performs elemental analysis based on the spectrum data (EDS spectrum data, WDS spectrum data) from the signal processing unit 604.

6.2. In the processing electron microscope 600, the line profile analysis unit 38 calculates the diffraction pattern based on the result of elemental analysis using the X-ray detector 602.

First, the X-rays generated by irradiating the analysis points with electron beams are detected by the X-ray detector 602, the elemental analysis unit 39 performs elemental analysis of the analysis points, and the composition information as a result of the elemental analysis is acquired. Based on this composition information, the line profile analysis unit 38 generates a reference line profile and registers it in the database, as in the case of the electron microscope 500. Other processing is the same as that of the electron microscope 500, and the description thereof will be omitted.

The detection of X-rays by the X-ray detector 602 at the analysis point and the detection of the diffraction pattern by the electron detector 508 at the analysis point may be performed at the same time. Further, first, X-rays are detected by the X-ray detector 602 at the analysis point, the measurement conditions (incident energy, etc.) for detecting the diffraction pattern from the result of the elemental analysis are determined, and the diffraction by the electron detector 508 is performed. Pattern detection may be performed.

6.3. Features The electron microscope 600 has the following features, for example.

The electron microscope 600 includes an X-ray detector 602 that detects X-rays generated by irradiating the sample S with an electron beam, and the line profile analysis unit 38 uses the X-ray detector 602 as a result of element analysis. Based on this, the diffraction pattern is calculated. Therefore, in the electron microscope 600, the information of the sample can be accurately acquired, and the reference line profile can be generated accurately.

For example, in the electron microscope 500, the user had to know the composition information of the sample, but in the electron microscope 600, it is not necessary. Therefore, the electron microscope 600 can easily analyze the crystal orientation.

Further, in the electron microscope 600, since the crystal orientation can be analyzed by using the electron detector 508, the crystal orientation can be analyzed in a horizontal state without tilting the sample S. Therefore, it is easy to match the result of the elemental analysis obtained by the X-ray detector 602.

For example, when the crystal orientation of the sample S is specified by the EBSD method, the sample S must be tilted greatly. However, the X-ray detector 602 cannot be used in such a state where the sample S is greatly tilted. Therefore, the analysis result of the crystal orientation by the EBSD method obtained in the state where the sample S is greatly tilted and the result of the elemental analysis using the X-ray detector 602 obtained in the state where the sample S is horizontal are matched. It's difficult. On the other hand, since the electron detector 508 can be used under the same conditions as the X-ray detector 602, such a problem does not occur.

The first to third modifications of the electron microscope 500 described above can also be applied to the electron microscope 600.

7. Seventh Embodiment 7.1. Electron Microscope Next, the electron microscope according to the seventh embodiment will be described with reference to the drawings. FIG. 37 is a diagram showing the configuration of the electron microscope 700 according to the seventh embodiment.

Hereinafter, in the electron microscope 700 according to the seventh embodiment, the same reference numerals are given to the members having the same functions as the constituent members of the electron microscope 100 according to the first embodiment and the electron microscope 500 according to the fifth embodiment. , The detailed description thereof will be omitted.

The electron microscope 700 includes both the electron detector 8 and the electron detector 508, as shown in FIG. 37.

FIG. 38 is a plan view schematically showing the electron detector 8 and the electron detector 508 mounted on the electron microscope 700.

As shown in FIG. 38, n'detection regions 509 are arranged so as to surround n detection regions 9 formed by dividing the annular detection surface in the circumferential direction. The electron detector 8 and the electron detector 508 are integrally configured and can operate at the same time.

The electron detector 8 and the electron detector 508 may be separate bodies. Further, although not shown, the electron microscope 700 may be configured to include a moving mechanism for moving the electron detector 8 and a moving mechanism for moving the electron detector 508. In this case, when the electronic detector 8 is used, the electronic detector 8 is moved onto the optical axis OA and the electronic detector 508 is retracted from the optical axis OA, and when the electronic detector 508 is used. , The electron detector 508 is moved onto the optical axis OA, and the electronic detector 8 is retracted from the optical axis OA.

7.2. Since the processing electron detector 508 has a small area of one detection area 509, the amount of signals that can be acquired per unit time is small. Therefore, in the electron detector 508, the time for irradiating the analysis point with the electron beam must be longer than that in the electron detector 8.

However, if the time for irradiating the electron beam is lengthened, problems such as contamination of the sample, deformation of the sample due to heat, and charging of the sample occur. Therefore, in the electron microscope 700, by including both the electron detector 8 and the electron detector 508, the scanning speed of the electron beam can be increased by using the electron detector 8 and the shape of the crystal grains can be confirmed (for example,). A crystal orientation image can be obtained by acquiring a pattern analysis image, a grain boundary image, etc.) and analyzing the crystal orientation with at least one point in the crystal grain as an analysis point using an electron detector 508. Hereinafter, this process will be specifically described.

As described in the first embodiment described above, it is possible to acquire a crystal grain boundary image in which the shape of the crystal grain can be confirmed by using the electron detector 8.

FIG. 39 is a diagram schematically showing the grain boundary image I2. FIG. 40 is a diagram schematically showing a state in which an inscribed circle is drawn on the crystal grain boundary image I2.

In the crystal grain boundary image I2, an analysis point is set for each crystal grain. For example, as shown in FIG. 40, an inscribed circle is drawn on a crystal grain in a grain boundary image, the center of the inscribed circle is obtained, and this center is used as an analysis point. This process is performed on all the crystal grains in the grain boundary image. Thereby, one analysis point can be set for one crystal grain.

With respect to the analysis points set for each crystal grain in this way, the crystal orientation is specified by the process described in the fifth embodiment described above. As a result, the crystal orientation of the crystal grains in the crystal grain boundary image I2 can be specified, and the crystal orientation image can be generated.

7.3. Process flow Next, the process flow of the processing unit 30 of the electron microscope 700 according to the seventh embodiment will be described. FIG. 41 is a flowchart showing an example of the processing flow of the processing unit 30 of the electron microscope 700 according to the seventh embodiment.

First, the intensity pattern information generation unit 32, the pattern analysis unit 33, and the image generation unit 34 generate the intensity pattern shown in FIG. 16 (S100), the pattern analysis information generation process (S102), and the image generation. The process (S104) is performed to acquire a grain boundary image (S500).

Next, the intensity pattern information generation unit 32 sets an analysis point for each crystal grain in the crystal grain boundary image (S502). The intensity pattern information generation unit 32 draws an inscribed circle on the crystal grains in the crystal grain boundary image, obtains the center of the inscribed circle, and performs a process of using this center as an analysis point for all of the crystal grain boundary images. Perform on crystal grains.

Next, the intensity pattern information generation unit 32 and the line profile analysis unit 38 analyze the process of generating the reference line profile shown in FIG. 32 (S400), the process of acquiring the intensity line profile (S402), and the crystal orientation. The process (S404) is performed for all the set analysis points (S504). Thereby, the crystal orientation of all the crystal grains in the crystal grain boundary image can be specified.

The image generation unit 34 generates an image based on the crystal grain boundary image and the specific result (crystal orientation information) of the crystal orientation of the crystal grain (S506). The image generation unit 34 sets the crystal grains to the color and brightness corresponding to the crystal orientation based on the obtained crystal orientation information, and generates a crystal orientation image.

Next, the image generation unit 34 controls to display the generated crystal orientation image on the display unit 22 (S508). At this time, the image generation unit 34 may display the information of the crystal orientation specified on the generated crystal orientation image.

7.4. Features The electron microscope 700 has the following features, for example.

The electron microscope 700 includes both an electron detector 8 and an electron detector 508. Therefore, the crystal orientation image can be easily obtained.

The process of calculating the diffraction pattern based on the result of the elemental analysis using the X-ray detector 602 in the electron microscope 600 according to the sixth embodiment described above can also be applied to the seventh embodiment.

7.5. Modification Example A modification of the electron microscope 700 according to the seventh embodiment will be described.

In the seventh embodiment described above, the crystal orientation was analyzed at one point in the crystal grain. However, if one point of the sample is irradiated with an electron beam for a long time, local sample contamination will occur at this one point. If an SEM image is acquired at this location, sample contamination can be confirmed.

Therefore, in this modification, the electrons emitted from the sample S are detected by both the electron detector 8 and the electron detector 508 while scanning the electron beam. Then, a crystal grain boundary image is generated from the detection signal of the electron detector 8, crystal grains are specified, and the detection signals of the electron detector 508 acquired in one crystal grain are integrated to form one intensity line profile. Generate. As a result, the intensity line profile can be obtained without irradiating one point of the sample with an electron beam for a long time.

Further, in the above-mentioned seventh embodiment, the case where the crystal orientation is analyzed assuming that one crystal grain has the same crystal orientation has been described. However, the crystal orientation may differ even within the crystal grains. Even in such a case, since it can be seen that there is a change in the crystal orientation in the crystal grains in the crystal orientation image and the grain boundary image, the crystal orientation should be analyzed by increasing the number of analysis points for such crystal grains. You may go.

8. Others In the first to seventh embodiments described above, a low-energy electron beam is incident on the sample S whose surface is horizontal or close to horizontal (for example, the sample inclination angle is 10 ° or less). A clear diffraction pattern can be obtained. The reason will be described below.

When an electron beam is incident on a sample, it is scattered in the sample and electrons of various energies are emitted from the sample surface. The diffraction pattern used for the analysis of the crystal orientation by the EBSD method is an electron having a small energy loss with respect to the incident energy among the electrons emitted from the sample surface.

FIG. 42 is a graph showing the elastic scattering cross section of electrons with respect to iron atoms. The graph shown in FIG. 42 shows the amount of change in angle and its probability when a linearly moving electron approaches an atom and causes scattering due to the interaction between the electron and the atom.

First, consider the case where the energy of the electrons incident on the sample is high. As can be seen from the graph shown in FIG. 42, the high-energy electrons have a small angular change even if they are scattered in the sample. Further, the electrons incident on the sample do not scatter on the outermost surface of the sample, but penetrate to the depth of the mean free path and scatter, but the mean free path increases as the energy of the electrons increases. Therefore, when a high-energy electron beam is incident on the sample with the sample horizontal, that is, when a high-energy electron beam is incident on the sample perpendicularly to the sample surface, electron scattering occurs in a region relatively deep from the sample surface. Most of the electrons are scattered deep in the sample. Further, even if the electrons reach the surface of the sample and are emitted from the sample very rarely, such electrons are repeatedly scattered, so that the energy loss is large. Therefore, even if the sample is leveled and a high-energy electron beam is incident on the sample, very few electrons having a small energy loss forming a diffraction pattern are emitted from the sample surface.

Therefore, in the EBSD method, the sample is tilted greatly and the electron beam is incident on the sample surface from an oblique direction. As a result, the scattering region of electrons in the sample and the surface of the sample are close to each other, so that electrons with a small number of scatterings, that is, a small energy loss, can easily reach the surface of the sample. As a result, a large amount of electrons having a small energy loss forming the diffraction pattern are emitted from the sample surface, and it is easy to obtain the diffraction pattern.

Next, consider the case where the energy of the electrons incident on the sample is low. As shown in FIG. 42, low-energy electrons have a higher probability of being scattered in the 180 ° direction than high-energy electrons. Therefore, when a low-energy electron beam is incident on the sample, the amount of scattering in the direction opposite to the incident direction of the electron beam increases. Further, low-energy electrons have a shorter mean free path in the sample than high-energy electrons, so that scattering is likely to occur near the sample surface. Therefore, when a low-energy electron beam is incident on a sample, many electrons with little energy loss are emitted even if the sample surface is horizontal.

Therefore, a clear diffraction pattern can be obtained by injecting a low-energy electron beam into the sample S in which the sample surface is horizontal or close to horizontal (for example, the sample inclination angle is 10 ° or less). For example, the acceleration voltage is 10 kV or less, more preferably the acceleration voltage is 5.
It shall be kV or less. As a result, low-energy electrons can be incident on the sample S, and a clear diffraction pattern can be obtained even when the sample surface is horizontal or close to horizontal.

FIG. 43 is a graph showing the depth at which the electrons (reflected electrons) emitted from the sample are scattered. The horizontal axis shows the depth at which scattering occurred, and the vertical axis shows the percentage of electrons that caused scattering at that depth. In FIG. 43, the sample is gold.

The conditions of the acceleration voltage of 15 kV and the sample inclination angle of 70 deg are generally used for acquiring the Kikuchi line by the EBSD method. The sample tilt angle is the tilt angle of the sample surface with respect to the horizontal direction. In other words, the sample tilt angle is the tilt of the sample surface with respect to the horizontal plane, that is, 0 °. The electron beam is assumed to be incident on the sample from the vertical direction with respect to the horizontal plane.

When the acceleration voltage is 15 kV and the sample inclination angle is 70 deg, the ratio of the scattered electrons having a depth of 40 nm or less is 80% or more among the electrons emitted from the sample. In this way, by increasing the sample tilt angle, the depth at which electron scattering occurs can be made shallow, and the proportion of electrons with little energy loss among the electrons emitted from the sample can be increased. This makes it possible to obtain a clear diffraction pattern.

When the acceleration voltage is 15 kV and the sample inclination angle is 0 deg (that is, the sample surface is horizontal), scattering also occurs in a region deeper than 100 nm. Therefore, under this condition, the contrast of the diffraction pattern is very weak, and a clear diffraction pattern cannot be obtained.

On the other hand, when the acceleration voltage is 5 kV and the sample inclination angle is 0 deg, the scattering is concentrated in a shallow place. As shown in FIG. 43, when the acceleration voltage is 5 kV and the sample inclination angle is 0 deg, the depth at which the electrons are scattered is concentrated at 40 nm or less. Specifically, when the acceleration voltage is 5 kV and the sample inclination angle is 0 deg, the proportion of electrons with a scattering depth of 40 nm or less among the electrons emitted from the sample is 90% or more. By lowering the acceleration voltage in this way, even if the sample surface is horizontal or close to horizontal, the depth at which electrons scatter can be made shallow, and energy loss occurs in the electrons emitted from the sample. It is possible to increase the proportion of electrons with few electrons.

As described above, when the sample is held so that the surface of the sample is horizontal or close to horizontal (for example, the sample inclination angle is 10 ° or less), low energy electron beams are incident on the sample to generate electrons. Scattering occurs in the shallow region of the sample, and electrons with little energy loss are emitted from the sample. As a result, a clear diffraction pattern is projected on the surface on which the electron detector 8 and the electron detector 508 are arranged.

By incidenting a low-energy electron beam on the sample, the electron scattering region becomes smaller than in the case where a high-energy electron beam is incident on the sample. As a result, the region where reflected electrons are generated becomes smaller, which enables directional analysis with high spatial resolution.

The above-described embodiments and modifications are merely examples, and the present invention is not limited thereto. For example, each embodiment and each modification can be combined as appropriate.

The present invention includes substantially the same configurations as those described in the embodiments (eg, configurations with the same function, method and result, or configurations with the same purpose and effect). The present invention also includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. Further, the present invention includes a configuration having the same action and effect as the configuration described in the embodiment or a configuration capable of achieving the same object. Further, the present invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

2 ... electron source, 3 ... convergent lens, 4 ... objective lens, 5 ... scanning deflector, 6 ... sample stage, 8 ... electron detector, 9 ... detection area, 10 ... scanning signal generator, 12 ... amplifier, 14 ... Signal regulator, 16 ... signal acquisition unit, 18 ... signal converter, 20 ... operation unit, 22 ... display unit, 24 ... storage unit, 26 ... database, 30 ... processing unit, 32 ... intensity pattern information generation unit, 33 ... Pattern analysis unit, 34 ... image generation unit, 36 ... control unit, 38 ... line profile analysis unit, 39 ... element analysis unit, 100 ... electron microscope, 200 ... electron microscope, 300 ... electron microscope, 302 ... EBSD detector, 400 ... Electron microscope, 402 ... Sample loading unit, 500 ... Electron microscope, 508 ... Electron detector, 509 ... Detection area, 510 ... Movement mechanism, 600 ... Electron microscope, 602 ... X-ray detector, 604 ... Signal processing unit, 700 ... Electron microscope

Claims (17)

A plurality of detectors that detect charged particles diffracted by the sample by irradiating the sample with a charged particle beam, and
An intensity pattern information generation unit that generates intensity pattern information representing the intensities of the plurality of detection signals as a graphic based on the intensities of the plurality of detection signals output from the plurality of detection units.
A scanning deflector for scanning the sample with the charged particle beam,
A pattern analysis unit that analyzes the intensity pattern information associated with the incident position of the charged particle beam with respect to the sample, and a pattern analysis unit.
An image generation unit that generates a pattern analysis image showing the distribution of the crystal orientation of the sample based on the analysis result of the pattern analysis unit.
Including
The plurality of detectors are composed of a split detector in which the first to nth detection regions are formed by dividing the annular detection surface centered on the optical axis in the circumferential direction.
The first to nth detection signals are output from the first to nth detection regions, respectively.
The figure is a charged particle beam device created by plotting the intensities of the first to nth detection signals on the intensity axes of the first to nth detection signals, respectively . In claim 1,
The intensity axis of the first to nth detection signals is a charged particle beam device in which the origin is at the same position and extends radially . In claim 1 or 2 ,
The first to nth detection regions are arranged in rotational symmetry.
The pattern analysis unit is a charged particle beam device that compares the reference intensity pattern information as a reference with the intensity pattern information. In claim 3,
The pattern analysis unit is a charged particle beam device that acquires the reference intensity pattern information based on the intensity pattern information associated with the incident position of the charged particle beam with respect to the sample. In claim 3 or 4,
The sample includes a detector that acquires a diffraction pattern obtained by irradiating the sample with the charged particle beam.
The image generation unit is a charged particle beam device that identifies crystal orientations in pixels constituting the pattern analysis image based on the diffraction pattern. In claim 5,
The pattern analysis unit
In each of the plurality of pixels constituting the pattern analysis image, the intensity pattern information in the pixel and the reference intensity pattern information are compared to group the pixels.
A charged particle beam device that acquires the diffraction pattern for each group and identifies the crystal orientation in the group. In claim 5 or 6,
The pattern analysis unit
Based on the diffraction pattern, the crystal orientation of the crystal grains is specified in the pattern analysis image.
Among the crystal grains included in the pattern analysis image, the crystal orientation of the crystal grain whose crystal orientation could not be specified based on the diffraction pattern is used as the intensity pattern information of the crystal grain whose crystal orientation is specified based on the diffraction pattern. A charged grain beam device to identify based on. In claim 3,
The pattern analysis unit is a charged particle beam device that acquires the reference intensity pattern information from a database in which the reference intensity pattern information is registered for each crystal orientation. In claim 8,
The pattern analysis unit is a charged particle beam device that specifies the crystal orientation by comparing the reference intensity pattern information registered in the database with the intensity pattern information. In any one of claims 3 to 9,
The image generation unit generates a plurality of the pattern analysis images in response to a plurality of scans of the charged particle beam.
A charged particle beam device that shares the reference intensity pattern information in a plurality of the pattern analysis images. In claim 2,
The pattern analysis unit is a charged particle beam device that specifies a crystal orientation based on the symmetry of an intensity pattern based on the intensity pattern information. In claim 2,
The pattern analysis unit is a charged particle beam device that compares the reference intensity pattern information as a reference with the intensity pattern information, and the image generation unit generates a grain boundary image from which the crystal grain boundaries of the sample are extracted. In any one of claims 1 to 12 ,
The intensity pattern information generation unit is a charged particle beam device that standardizes the intensities of a plurality of detection signals output from the plurality of detection units and generates the intensity pattern information. In claim 8 or 9,
A charged particle beam device in which a plurality of reference intensity pattern information having the same crystal orientation and different rotation angles of the crystal orientation are registered in the database. In claim 3,
The pattern analysis unit rotates the figure specified by the reference intensity pattern information relative to the figure specified by the intensity pattern information, and makes a comparison for each rotation. Device. In claim 3,
The pattern analysis unit is a charged particle beam device that obtains the Euclidean distance between the reference intensity pattern information and the intensity pattern information, and determines the similarity between the reference intensity pattern information and the intensity pattern information based on the Euclidean distance. A step of scanning a sample with a charged particle beam and detecting charged particles diffracted by the sample by irradiating the sample with the charged particle beam by a plurality of detection units.
A step of generating intensity pattern information representing the intensities of the plurality of detection signals as a graphic based on the intensities of the plurality of detection signals output from the plurality of detection units .
A step of analyzing the intensity pattern information associated with the incident position of the charged particle beam with respect to the sample, and
A step of generating a pattern analysis image showing the distribution of the crystal orientation of the sample based on the analysis result in the step of analyzing the intensity pattern information, and a step of generating the pattern analysis image.
Including
The plurality of detectors are composed of a split detector in which the first to nth detection regions are formed by dividing the annular detection surface centered on the optical axis in the circumferential direction.
The first to nth detection signals are output from the first to nth detection regions, respectively.
The figure is an analysis method, which is a figure created by plotting the intensities of the first to nth detection signals on the intensity axes of the first to nth detection signals, respectively .

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