JP6805945B2 - Analytical method and analyzer - Google Patents

Description

The present invention relates to an analytical method and an analyzer.

Stress is one of the important factors that influence the characteristics of electronic devices.
With the miniaturization of electronic devices, it is extremely important to measure how stress is applied, for example, in the vicinity of the gate of a transistor.
In recent years, not only in electronic devices but also in various functional materials, local stresses that cannot be predicted at the design stage are applied to actual samples due to high integration and high-density lamination, and their values can be measured. It is needed.

Japanese Unexamined Patent Publication No. 2004-093263 Japanese Unexamined Patent Publication No. 2005-121552 Japanese Unexamined Patent Publication No. 2006-153894

However, since it is difficult to directly measure the stress in a fine region, it is an indirect measurement that measures the deformation of the sample due to the stress and analyzes how much stress is applied to the stress source. The method is taken. The deformation of the sample is measured as the amount of strain (curvature).
Here, there are roughly two measurement methods using the microscopic technique.
First, there is a measurement method using an atomic force microscope in which a minute needle is brought into contact with the sample surface and unevenness is detected by a change in the interatomic force.

Although this method has high sensitivity for detecting unevenness, it has poor spatial resolution, and it is extremely difficult to measure a region of several nm, for example.
Next, as a measurement method with high spatial resolution, there is a measurement method using the convergent electron diffraction method, which is a technique of an electron microscope.
This method is a method of measuring the amount of strain (curvature) by matching with theoretical analysis by utilizing the change in the pattern of the electron diffraction image that occurs when an electron passes through a sample having strain or curvature.

This method is a measurement method with high spatial resolution because the incident region of the electron beam can be limited to several nm, for example.
However, measurement is difficult unless a clear pattern is obtained in the electron diffraction image, and in order to obtain a clear electron diffraction image, for example, it is necessary to have high crystallinity and limit the incident direction. Become. Therefore, for example, it is difficult to apply it to a sample having many defects or a sample having a complicated crystal structure.

An object of the present invention is to enable the amount of strain to be measured (calculated) with high spatial resolution and with high accuracy without being limited by, for example, crystallinity or incident direction or restricted by a sample.

In one embodiment, the analysis method is a step of reading an atomic resolution image acquired while changing the amount of defocus by a spherical aberration-corrected scanning transmission electron microscope and calculating the contrast value of each of a plurality of regions of the atomic resolution image. And the step of associating the position where the contrast value of each of the plurality of regions is maximized with the amount of defocus and calculating the amount of distortion occurring in each region of the analysis target corresponding to each of the plurality of regions.

In one embodiment, the analyzer reads the atomic resolution image acquired by the spherical aberration-corrected scanning transmission electron microscope while changing the defocus amount, and calculates the contrast value of each of the plurality of regions of the atomic resolution image. The amount of distortion that calculates the amount of distortion occurring in each area of the analysis target corresponding to each of the plurality of areas by associating the value calculation unit with the position where the contrast value of each of the plurality of areas is maximized and the amount of defocus. It has a calculation unit.

As one aspect, it has an effect that the amount of strain can be measured (calculated) with high spatial resolution and with high accuracy without being limited by, for example, crystallinity, incident direction, etc. or restricted by a sample.

It is a figure which shows the structure of the analyzer which concerns on this embodiment. It is a flowchart for demonstrating the process (analysis method) in the analyzer which concerns on this embodiment. It is a flowchart for demonstrating the process (analysis method) in the analyzer which concerns on this embodiment. It is a figure which shows the electron microscope image which displayed the distorted part of a sample as an contour map. It is a figure which conceptually showed the acquisition method of the unevenness image by a scanning probe microscope. It is a figure which conceptually showed the measurement method of the strain amount (curvature amount) using convergent electron diffraction. (A) to (D) are diagrams showing the characteristics of the electron probe obtained before and after the correction of spherical aberration. It is a figure for demonstrating the principle of this invention. It is a figure for demonstrating the principle of this invention. It is a figure which shows the STEM image acquired using the sample which is actually distorted (curved). It is a figure which showed the strain amount distribution (curvature distribution) in the actually acquired STEM image. It is a figure which shows the hardware configuration of the analyzer which concerns on this embodiment.

Hereinafter, the analysis method and the analysis apparatus according to the embodiment of the present invention will be described with reference to FIGS. 1 to 12.
Due to the high integration and high density stacking of materials, local stresses that cannot be predicted at the design stage are applied to the actual sample, and it is necessary to measure the value.
However, since it is difficult to directly evaluate the stress in the local region, how much pressure must be applied to the stress source in order to measure the strain (curvature) of the sample and reproduce the strain (curvature). An indirect measurement method such as whether or not there is is used.

Here, as an example, FIG. 4 shows a region where distortion (curvature) of an electron microscope image is visualized by a transmission electron microscope of a strain distribution (curvature distribution) occurring in a sample such as an electronic device with a contour map. It is shown.
The amount of distortion (amount of curvature) can be obtained as the intensity of the image, but the spatial resolution is limited to about several tens of nm, and the amount of distortion (amount of curvature) should be standardized only from the intensity information of the image. Therefore, it is necessary to separately relate the image intensity and the amount of distortion (amount of curvature) by using another method.

Scanning probe microscopy is one of the most common methods for quantitatively measuring the amount of strain (curvature) as shown in FIG.
In this scanning probe microscopy, as shown in FIG. 5, the minute short hand provided on the cantilever is scanned while measuring the atomic force so as to trace the sample surface. In addition, the measured atomic force is fed back to the needle so that it becomes constant, and the vertical movement of the needle is recorded. Further, since the needle moves up and down in response to the unevenness of the sample in order to keep the interatomic force constant, the unevenness of the sample can be measured by recording the vertical movement of the needle. By using this method, it is possible to obtain an uneven image of the sample and directly measure the amount of strain (curvature). In FIG. 5, P indicates stress and t indicates thickness.

However, since the spatial resolution is limited to several tens of nm or more, it is not sufficient for the measurement of current highly integrated devices, for example.
As a method of measuring the amount of strain (curvature amount) with higher spatial resolution, there is a method using convergent electron diffraction, which is a method of transmission electron microscopy.
In this method, as shown in FIG. 6, an electron diffraction image obtained by injecting an electron probe converged to several nm or less into a sample is used. It is known that the pattern of an electron diffraction image is complicatedly changed not only by the structure and thickness of the sample but also by the strain (curvature) of the sample. Therefore, by comparing the experimentally acquired convergent electron diffraction image (experimental image) with the diffraction image (calculated image) calculated using the strain amount (curvature amount) as a parameter, the calculation conditions that can explain the experimental image most. Is output. Since the thickness and strain amount (curvature amount) of the sample are included in this calculation condition, as a result, the strain amount (curvature amount) can be quantitatively obtained. For example, it is possible to reproduce the change in the diffraction image caused by the curvature (distortion) by theoretical analysis with the strain amount (curvature amount) as a variable, and indirectly measure the strain amount (curvature amount). In FIG. 6, P indicates stress, t indicates thickness, and Δθ indicates the amount of curvature.

Since this method has extremely high measurement accuracy and the spatial resolution is also defined by the radius of convergence of the electron beam, it is possible to obtain a strain amount (curvature amount) with a high spatial resolution of several nm.
However, it is not possible to observe any sample because a diffraction image suitable for analysis (analysis) may not be obtained depending on the shape and structure of the sample, the incident direction, and the like.
Therefore, by constructing a system for acquiring information on strain (curvature) from an image having a spatial resolution high enough to obtain an atomic resolution image, which is an advantage of transmission electron microscopy, for example, the shape of a sample, We want to be able to easily measure the strain distribution (curvature distribution) with high spatial resolution without being restricted by the structure, incident direction, etc.

In this case, in order to acquire an atomic resolution image, a spherical aberration-corrected scanning transmission electron microscope (Spherical aberration-corrected STEM), which is one of scanning transmission electron microscopy (STEM), may be used.
In the spherical aberration correction STEM, the spherical aberration can be made as close to zero as possible compared to other STEMs, and it is possible to use an electromagnetic lens having a large aperture.

Therefore, it is possible to form an electron probe having a high current density and to construct an electromagnetic lens having an extremely shallow depth of focus. As a result, it becomes possible to focus the electron probe near the sample surface.
Here, FIGS. 7 (A) to 7 (D) are diagrams showing the characteristics of the electron probe obtained before and after the correction of spherical aberration.

7 (A) and 7 (B) show probe functions (device functions) obtained before and after spherical aberration correction, respectively.
As shown in FIGS. 7 (A) and 7 (B), it can be seen that a probe having a high current density can be constructed by correcting the spherical aberration.
7 (C) and 7 (D) show how the electrons are localized in the crystal before and after the spherical aberration correction, respectively.

As shown in FIGS. 7 (C) and 7 (D), when the spherical aberration is finite (before the correction of the spherical aberration), the depth of focus becomes deep, and as a result, the position where the image is focused is inside the image. On the other hand, when spherical aberration is corrected (after correction of spherical aberration), electrons can be localized in an extremely small region near the sample surface, and as a result, the image is focused near the sample surface. It becomes.
By utilizing the characteristics of the electron probe after such correction of spherical aberration, the amount of strain (curvature) can be quantified.

Here, as shown in FIG. 8, first, the vertical position of the electron probe is set so as to be the positive focal position in a part of the sample.
Then, the position of the sample (or the electron probe) is scanned in the horizontal direction of the paper surface of FIG. 8 without changing the probe position and the height position of the sample [reference numerals (A), (B), (C) in FIG. )reference]. Here, the case of scanning in the horizontal direction is shown.

In this case, since the focal point is focused inside at the position where the sample is curved, the focal position is relatively deviated.
Here, FIG. 9 shows an experimental image (Exp.) (upper row in the figure) and a calculated image (Sim.) (Lower row in the figure) acquired at various focal positions (defocus amounts). There is. The sample is SrTiO3 (100).

As shown in FIG. 9, when the focal position is aligned, that is, when the defocus amount is 0, the contrast (contrast value) of the image is maximized, but when the focal position is deviated, that is, defocused. It can be seen that as the amount increases, the coton trust (contrast value) of the image decreases.
In the case of the sample as shown in FIG. 8 above, since the electron probe remains in focus at the positions of the symbols (A) and (B) in FIG. 8, the image having the maximum contrast value (for example, the center of FIG. 9). An image as in the case where the defocus amount of is 0) is obtained. On the other hand, when the electron probe comes to the position of the symbol (C) in FIG. 8, the focal position is relatively deviated, so that the contrast value is reduced and the contrast is blurred (for example, the image on the left side of FIG. 9). An image as in the case of a focus amount of -40) is acquired.

By utilizing such a feature, the strain amount (curvature amount) can be obtained from the defocus amount (defocus amount), and the strain distribution (curvature distribution) can be visualized.
Here, FIG. 10 shows the result of acquiring an image using a sample that is actually curved (a sample in which distortion occurs).
Sample is a sample prepared by laminating a BaSnO _3, SrSnO _3, SrTiO ₃ on SrTiO ₃ substrate. In addition, since the lattice constants of each layer of this sample are different, stress is generated when the samples are laminated, strain is generated, and the sample is curved.

Further, as a STEM image, an electron probe is actually scanned to obtain a single image. In addition, in order to measure the deterioration of the image due to the change in focus (change in the amount of defocus), a one-frame through focal image is used to acquire the image by continuously changing the focus (amount of defocus) when acquiring the image. The one-frame through focal STEM image is acquired.
Further, the electron probe scans one pixel in the horizontal direction, then moves one pixel in the vertical direction, and scans in the horizontal direction. Therefore, if the focus (defocus amount) is continuously changed, an image in which the focus (defocus amount) changes in the vertical direction can be obtained.

By calculating the contrast value of each region corresponding to each layer of the image acquired in this way, identifying the position where the contrast value is maximized, and associating this with the defocus amount, each layer corresponding to each region. The amount of distortion (amount of curvature) can be obtained. The amount of strain is the amount of displacement in the in-plane direction of each region of the sample and the amount of displacement of each region of the sample. Further, here, since the resolution is high, the amount of strain and the amount of curvature are almost synonymous.

Here, the continuously changed defocus amount can be recorded in the order of the distance, and can be associated with the vertical distance of the acquired image, so that the position where the contrast value is maximized. Can be associated with the defocus amount to obtain the strain amount (curvature amount) of each layer.
Further, as shown in FIG. 11, a region having the maximum contrast value (a region surrounded by a square in FIG. 11; a minute area; a positive focus position) is displayed on the image acquired in this manner, and the region is displayed. By plotting the center position of (solid line X in FIG. 11), it can be displayed as a strain amount distribution (curvature distribution).

Here, the continuously changed defocus amount can be recorded in the order of the distance, and can be associated with the vertical distance of the acquired image, so that the horizontal direction of the acquired image can be associated with the distance. By plotting the position of and the positive focus position (solid line X in FIG. 11), it is possible to display as a strain amount distribution (curvature distribution).
Moreover, since it is possible to measure in principle if an atomic resolution image can be obtained, the spatial resolution is on the order of sub-nanometer meters. Further, since the crystal zone axis incident is not required as in the case of acquiring a convergent electron diffraction image, there are almost no restrictions on the sample.

Hereinafter, the configuration of the analyzer and the processing (analysis method) in the analyzer according to the present embodiment will be described with reference to FIGS. 1 to 3.
First, the analyzer of the present embodiment is an apparatus that analyzes an atomic resolution image acquired by a spherical aberration-corrected scanning transmission electron microscope (hereinafter, also simply referred to as an electron microscope).
The analyzer is also referred to as a measuring device. Further, here, since the analyzer is an apparatus for measuring (quantitative measurement) the strain amount distribution (curvature distribution), this is also referred to as a strain amount distribution measuring apparatus (curvature distribution measuring apparatus).

For example, an electron microscope is connected to the analyzer to form an analysis system, and an atomic resolution image acquired by the electron microscope is input to the analyzer. The present invention is not limited to this, and for example, the atomic resolution image acquired by the electron microscope may be input to the analyzer via the network.
Here, FIG. 1 is a functional block diagram of the analyzer.

As shown in FIG. 1, the present analyzer 1 includes a focus adjustment unit 2, a contrast value calculation unit 3, a strain amount calculation unit 4, and a display control unit 5.
Here, the focus adjustment unit 2 changes the focus position positively and negatively to acquire an atomic resolution image, and changes the focus position (focus change amount; focus adjustment amount) to the electron microscope 6 (here, the electron microscope 6). Instruct the provided focus changing unit 7).

Further, the focus adjusting unit 2 determines the amount of change in the focal position (amount of focus change; amount of focus adjustment; amount of defocus) when acquiring an atomic resolution image while changing the amount of defocus (amount of defocus). (Here, the focus changing unit 7 provided in the electron microscope 6) is instructed.
Further, the focus adjusting unit 2 includes a defocus range setting unit 8.
The defocus range setting unit 8 sets a range in which the defocus amount is changed based on the peak intensity of the atomic resolution image obtained by changing the focal position positively or negatively.

That is, the defocus range setting unit 8 reads the atomic resolution image acquired by changing the focal position positively and negatively by the electron microscope 6, and changes the defocus amount based on the peak intensity of the atomic resolution image (acquired image). Set the range to be made.
The range for changing the defocus amount set by the defocus range setting unit 8 is used when acquiring an atomic resolution image while changing the defocus amount with the electron microscope 6.

The details of the method of setting the range for changing the defocus amount will be described later.
The contrast value calculation unit 3 reads the atomic resolution image acquired by the electron microscope 6 while changing the defocus amount, and calculates the contrast value of each of a plurality of regions of the atomic resolution image (acquired image).
The strain amount calculation unit 4 associates the position where the contrast value of each of the plurality of regions is maximum with the defocus amount, and calculates the strain amount generated in each region of the analysis target corresponding to each of the plurality of regions. ..

For example, the strain amount calculation unit 4 calculates the difference in the defocus amount corresponding to the position where the contrast value of each region is maximized, that is, the positive focus position, and thereby the strain amount generated in each region to be analyzed. Is calculated.
At this time, the strain amount calculation unit 4 obtains the maximum value of the contrast value of each region calculated by the contrast value calculation unit 3, and specifies the position where the contrast value of each region is maximum. The position where the contrast value of each region is maximized is the positive focus position. Therefore, the strain amount calculation unit 4 has identified the positive focal position.

The display control unit 5 plots the position where the contrast value of each of the plurality of regions is maximized and displays it as a distortion amount distribution (curvature distribution) (see, for example, FIG. 11).
That is, the display control unit 5 plots the position where the contrast value of each of the plurality of regions is maximized (positive focus position) as a function of each region to be analyzed, and plots the distortion amount distribution (curvature distribution) as the image output unit ( Display device) Controls the display on the screen of 9.

The strain amount distribution is also referred to as a strain amount profile or a strain distribution. The curvature distribution is also referred to as a curvature profile or a curvature distribution.
As described above, in the present embodiment, the strain amount (curvature) of the sample is measured by using the atomic resolution image acquired by the spherical aberration-corrected scanning transmission electron microscope 6.
Since the atomic resolution image is used, the spatial resolution is extremely high, and the spatial resolution is higher than that of the existing method using the convergent electron diffraction image.

In addition, by using spherical aberration correction, it becomes possible to form a large-diameter incident electron probe using a large-diameter lens, the depth of focus becomes shallow, and the positive focus position is set near the surface of the sample. This characteristic makes it possible to measure the amount of strain (curvature).
That is, when the focus is on a position where there is no curvature (distortion), a clear atomic resolution image can be obtained because the focus is on the sample surface. Then, when the electron probe is moved to a curved region (a region where distortion occurs) while keeping the height constant, the sample does not hit the positive focal position (near the sample surface) due to the curvature (distortion), and the image is displayed. It becomes unclear.

Utilizing this characteristic, a one-frame through focal STEM image that continuously changes the defocus amount (out-of-focus amount) when the image is acquired is acquired. Then, when there is curvature (distortion), the atomic resolution image becomes unclear due to deviation from the position aligned with the positive focus.
Since the out-of-focus amount can be measured on the order of nanometers, the amount of curvature (distortion amount) can be measured with high accuracy by monitoring the amount of focus change (defocus amount) corresponding to the out-of-focus position. Is possible.

Further, in the present embodiment, the electron microscope 6 acquires an atomic resolution image (one experimental image) while continuously changing the defocus amount based on the instruction from the focus adjusting unit 2, and the atomic resolution thereof. By calculating the contrast value of each region of the image and specifying the position where the contrast value of each region is maximized (positive focus position), the position where the image of each region of the atomic resolution image becomes clear is specified, and the position is specified. The amount of distortion (amount of curvature) is calculated by associating the position with the amount of defocus.

In this way, by monitoring the change in the positive focus position in each region of the sample in which the strain (curvature) occurs and associating it with the amount of defocus, the strain (curvature) occurring in the sample can be resolved with high spatial resolution. It is possible to measure with high accuracy. Further, it is sufficient that an atomic resolution image can be obtained, and the image may be an image in only one direction such as a lattice fringe, and is not restricted by the crystal orientation or the like.

Further, in the present embodiment, the electron microscope 6 acquires an atomic resolution image by gradually changing the focal position positively or negatively based on the instruction from the focus adjusting unit 2, and is based on the peak intensity of the atomic resolution image. The range in which the defocus amount is changed is set, which makes it possible to improve the accuracy when calculating the strain amount (curvature amount) as described above.
Next, the processing (analysis method) in the analyzer of the present embodiment will be described.

The analysis method of the present embodiment is a step of reading the atomic resolution image acquired while changing the defocus amount by the electron microscope 6 and calculating the contrast value of each of the plurality of regions of the atomic resolution image (step S4 in FIG. 2). (See) and the process of calculating the amount of distortion occurring in each region of the analysis target corresponding to each of the plurality of regions by associating the position where the contrast value of each of the plurality of regions is maximized with the amount of defocus (Fig.). 2) and is included.

In particular, in the present embodiment, a step of setting a range in which the defocus amount is changed based on the peak intensity of the atomic resolution image obtained by changing the focal position positively or negatively (see steps S1, S2, and 3 in FIG. 2). ) Is further included.
Further, the present embodiment further includes a step of plotting the position where the contrast value of each of the plurality of regions is maximized and displaying it as a strain amount distribution (see step S5 in FIG. 2).

Here, FIG. 2 is a flowchart showing a processing flow in the analysis method in the present embodiment.
First, in steps S1 and S2, the analyzer 1 sets a range in which the defocus amount is changed by the defocus range setting unit 8 included in the focus adjustment unit 2.
Here, the range for changing the defocus amount is a range set so that the focal position deviates positively or negatively in all regions (observation regions) of the sample (analysis target), that is, an atomic resolution image, as will be described later. It is a range set so that the peak intensity is included in all of the plurality of regions, and is used when acquiring an atomic resolution image while changing the defocus amount by the electron microscope 6.

Here, first, the analyzer 1 sets a condition (focus position) in which the defocus range setting unit 8 included in the focus adjustment unit 2 can focus on any region of the analysis target and acquire an atomic resolution image. (Step S1).
Next, the analyzer 1 changes the defocus amount based on the peak intensity of the atomic resolution image obtained by changing the focus position positively or negatively by the defocus range setting unit 8 included in the focus adjustment unit 2. Is set (step S2).

That is, the analyzer 1 instructs the electron microscope 6 to acquire an atomic resolution image by changing the focal position positively and negatively by the defocus range setting unit 8 included in the focus adjusting unit 2.
At this time, the analyzer 1 provides the electron microscope 6 (here, the electron microscope 6) with the amount of change in the focus position (focus change amount; focus adjustment amount) by the defocus range setting unit 8 included in the focus adjustment unit 2. Instruct the focus changing unit 7).

Then, the analyzer 1 reads the atomic resolution image acquired by changing the focal position to positive or negative by the electron microscope 6 by the defocus range setting unit 8 included in the focus adjustment unit 2, and the atomic resolution image (acquired image). ) Set the range to change the defocus amount based on the peak intensity.
Here, the atomic resolution image acquired by the electron microscope 6 is read into the analyzer 1 from the electron microscope 6 connected to the electron microscope 1, but the present invention is not limited to this, for example. , The atomic resolution image acquired by the electron microscope 6 may be read into the analyzer 1 via a network.

Specifically, by performing the processing as shown in the flowchart of FIG. 3, the analyzer 1 sets the range in which the defocus amount is changed by the defocus range setting unit 8 included in the focus adjustment unit 2.
First, the analyzer 1 can acquire an atomic resolution image by focusing on any region (analysis target region) of the analysis target by the defocus range setting unit 8 included in the focus adjustment unit 2 (focus position). Is set (step A1).

Next, the analyzer 1 sets the focal position as Df ₀ , Df ₊ , and Df ₋ as initial conditions by the defocus range setting unit 8 included in the focus adjustment unit 2 (step A2).
Next, the analyzer 1 instructs the electron microscope 6 to shift the focus (focus position) positively by the defocus range setting unit 8 included in the focus adjustment unit 2 (step A3). Here, the analyzer 1 instructs the electron microscope 6 of the amount of focus displacement such that the focus shifts in the positive direction by the defocus range setting unit 8 included in the focus adjustment unit 2.

Next, the analyzer 1 reads the atomic resolution image acquired by positively changing the focal position by the electron microscope 6 by the defocus range setting unit 8 included in the focus adjustment unit 2, and the peak of the atomic resolution image. It is determined whether or not the strength has decreased (step A4).
As a result of this determination, if it is determined that the peak intensity of the atomic resolution image has not decreased, the process proceeds to the NO route, returns to step A3, and the same process is repeated.

Then, if it is determined in step A4 that the peak intensity of the atomic resolution image has decreased, the process proceeds to the YES route, and the focal displacement amount at that time is recorded as Df ₊ '(step A5).
Next, the analyzer 1 instructs the electron microscope 6 to return the focus (focus position) to Df ₀ by the defocus range setting unit 8 included in the focus adjustment unit 2 (step A6).
Next, the analyzer 1 instructs the electron microscope 6 to shift the focus (focus position) negatively by the defocus range setting unit 8 included in the focus adjustment unit 2 (step A7). Here, the analyzer 1 instructs the electron microscope 6 of the amount of focus displacement such that the focus shifts in the negative direction by the defocus range setting unit 8 included in the focus adjustment unit 2.

Next, the analyzer 1 reads the atomic resolution image acquired by changing the focal position negatively by the electron microscope 6 by the defocus range setting unit 8 included in the focus adjustment unit 2, and the peak of the atomic resolution image. It is determined whether or not the strength has decreased (step A8).
As a result of this determination, if it is determined that the peak intensity of the atomic resolution image has not decreased, the process proceeds to the NO route, returns to step A7, and the same process is repeated.

Then, if it is determined in step A8 that the peak intensity of the atomic resolution image has decreased, the process proceeds to the YES route, and the amount of focal displacement at that time is recorded as Df ₋ ′ (step A9).
Next, in the analyzer 1, whether or not Df ₊ ′ recorded in step A5 is larger than Df ₊ set as the initial condition by the defocus range setting unit 8 included in the focus adjustment unit 2 (Df ₊ <Df). _{If +} ') is determined (step A10) and Df ₊ 'is determined to be larger than Df ₊ (YES route), the process proceeds to step A11, and Df ₊ set as the initial condition is rewritten to Df ₊ '(step A10). Df ₊ = Df ₊ ´), and the process proceeds to step A12.

On the other hand, when it is determined that Df ₊ 'is not larger than Df ₊ (NO route), the process proceeds to step A12.
Next, in step A12, the analyzer 1 determines whether or not the Df ₋ ′ recorded in step A9 is smaller than the Df ₋ set as the initial condition by the defocus range setting unit 8 included in the focus adjustment unit 2. If Df ₋ > Df ₊ ′) is determined and it is determined that Df ₋ ′ is smaller than Df ₋ (YES route), the process proceeds to step A13, and Df ₋ set as the initial condition is rewritten to Df ₋ ′ (Df ₋ ′). Df ₋ = Df ₋ ´), and the process proceeds to step A14.

On the other hand, when it is determined that Df ₋ ′ is not smaller than Df ₋ (NO route), the process proceeds to step A14.
Next, in step A14, the analyzer 1 determines whether there is another target area (analysis target area) by the defocus range setting unit 8 included in the focus adjustment unit 2, and when there is another target area. Instructs the electron microscope 6 to proceed to the YES route and move the electron probe to another target region (step A15).

Next, the analyzer 1 sets a focal position capable of acquiring an atomic resolution image by focusing on another target region by the defocus range setting unit 8 included in the focus adjusting unit 2 (step A16).
Next, the analyzer 1 sets the focus position to Df ₀ (step A17) by the defocus range setting unit 8 included in the focus adjustment unit 2, returns to step A3, and performs the same with respect to the other target area. The process (steps A3 to A13) is repeated.

Then, in step A14, the same processing (steps A15 to A17, A3 to A13) is repeated for the other target areas until it is determined that there is no other target area.
After that, if it is determined in step A14 that there is no other target area, the process proceeds to the NO route, and the analyzer 1 sets Df ₊ to Df ₋ by the defocus range setting unit 8 included in the focus adjustment unit 2. It is set as a range in which the defocus amount is changed (step A18).

After the range for changing the defocus amount is set in this way, in step S3 of FIG. 2, the analyzer 1 continuously applies the defocus amount to the electron microscope 6 within the range for changing the defocus amount. Instruct to acquire an atomic resolution image while changing.
Next, the analyzer 1 reads the atomic resolution image acquired by the contrast value calculation unit 3 while continuously changing the defocus amount within the range in which the defocus amount is changed by the electron microscope 6, and reads the atomic resolution image. The contrast value of each of the plurality of regions of is calculated (step S4).

Then, the analyzer 1 is generated in each region of the analysis target corresponding to each of the plurality of regions by associating the position where the contrast value of each of the plurality of regions is maximized with the defocus amount by the strain amount calculation unit 4. The amount of strain is calculated (step S4).
For example, the analyzer 1 uses the strain amount calculation unit 4 to calculate the position where the contrast value of each region is maximized, that is, the difference in the defocus amount corresponding to the positive focus position, so that each region to be analyzed can be analyzed. Calculate the amount of distortion that is occurring.

At this time, the analyzer 1 obtains the maximum value of the contrast value of each region calculated by the contrast value calculation unit 3 by the strain amount calculation unit 4, and specifies the position where the contrast value of each region is maximum. The position where the contrast value of each region is maximized is the positive focus position. Therefore, the strain amount calculation unit 4 identifies the positive focal position.
Next, the analyzer 1 plots the position (positive focus position) at which the contrast value of each of the plurality of regions of the atomic resolution image is maximized by the display control unit 5, and the strain amount distribution (curvature distribution; for example, FIG. 11). It is displayed as (see step S5).

That is, the analyzer 1 plots the position (positive focus position) at which the contrast value of each of the plurality of regions of the atomic resolution image is maximized as a function of each region to be analyzed by the display control unit 5, and the strain amount distribution. Control is performed to display the image output unit (display device) 9 on the screen as (curvature distribution).
Therefore, the analysis method and the analyzer according to the present embodiment measure (calculate) the strain amount (curvature amount) with high spatial resolution and high accuracy without being limited by, for example, crystallinity, incident direction, etc. or by the sample. ) Has the effect of being able to do it.

For example, in the atomic force microscopy, the spatial resolution was insufficient, but in the present embodiment, the measurement can be performed with the atomic resolution. Further, for example, even if the method using the convergent electron diffraction method has no defects and measurement is difficult unless a clear pattern can be obtained in the convergent electron diffraction image, the sample can obtain an atomic resolution image. For example, it is possible to measure strain (curvature) with high spatial resolution and high accuracy.

The present invention is not limited to the configuration described in the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, each function of the analyzer 1 and each process of the analysis method of the above-described embodiment shall be realized by hardware, firmware on a DSP (Digital Signal Processor) board or a CPU (Central Processing Unit) board, or software. Can be done.

For example, each function of the analyzer 1 and each process of the analysis method of the above-described embodiment can be realized by executing a program by a computer (including a processor such as a CPU, an information processing device, and various terminals). In this case, each function of the analyzer 1 and each process of the analysis method of the above-described embodiment may be realized by executing one program or a plurality of programs. In this way, when the computer executes the program to realize each function of the analyzer 1 and each process of the analysis method of the above-described embodiment, the program (one or more programs) is used for the analysis. Because it is a thing, it is called an analysis program.

Further, when each function of the analysis device 1 of the above-described embodiment and each process of the analysis method are realized by executing a program by a computer, the analysis device 1 of the above-described embodiment is as shown in FIG. 12, for example. This can be achieved by a computer with a hardware configuration. That is, the analysis device 1 of the above-described embodiment includes the CPU 102, the memory 101, the communication control unit 109, the input device 106, the display control unit 103, the display device 104, the storage device 105, and the drive device 107 of the portable recording medium 108. , These can be realized by a computer configured to be interconnected by a bus 110. The hardware configuration of the computer as the analyzer 1 of the above-described embodiment is not limited to this.

Here, the CPU 102 controls the entire computer, reads the program into the memory 101, executes the program, and performs the processing required for the analyzer 1 of the above-described embodiment.
The memory 101 is, for example, a main storage device such as a RAM, and temporarily stores a program or data when executing a program, rewriting data, or the like.

The communication control unit 109 (communication interface) is used for communicating with other devices via a network such as a LAN or the Internet. The communication control unit 109 may be built into the computer from the beginning, or may be a NIC (Network Interface Card) attached to the computer later.
The input device 106 is, for example, a touch panel, a pointing device such as a mouse, a keyboard, or the like.

The display device 104 is a display device such as a liquid crystal display.
The display control unit 103 controls the display device 104 to display, for example, an atomic resolution image or a strain amount distribution.
The storage device 105 is an auxiliary storage device such as a hard disk drive (HDD) or SSD, and stores various programs and various data. Here, the storage device 105 stores the analysis program. The memory 101 may be provided with, for example, a ROM (Read Only Memory), in which various programs and various data may be stored.

The drive device 107 is for accessing the storage contents of a semiconductor memory such as a flash memory, a portable recording medium 108 such as an optical disk and a magneto-optical disk, and the like.
In a computer having such a hardware configuration, the CPU 102 reads, for example, an analysis program stored in the storage device 105 into the memory 101 and executes it, thereby performing each function and the analysis method of the analysis device 1 of the above-described embodiment. Each process of is realized.

Further, here, the analyzer 1 of the above-described embodiment is configured as having an analysis program installed on a computer, but an analysis program for realizing each function of the analyzer 1 of the above-described embodiment on the computer. Alternatively, the analysis program for causing the computer to execute each process of the analysis method of the above-described embodiment may be provided in a state of being stored in a computer-readable recording medium.

Here, the recording medium includes, for example, a memory such as a semiconductor memory, a magnetic disk, an optical disk [for example, a CD (Compact Disc) -ROM, a DVD (Digital Versatile Disk), a Blu-ray disc, etc.], a magneto-optical disk (MO: Magneto optical Disc). ) Etc. can be recorded. A magnetic disk, an optical disk, a magneto-optical disk, etc. are also referred to as a portable recording medium.

In this case, the analysis program is read from the portable recording medium 108 via the drive device 107, and the read analysis program is installed in the storage device 105. As a result, the analysis device 1 and the analysis method of the above-described embodiment are realized, and the analysis program installed in the storage device 105 is read and executed by the CPU 102 on the main memory 101 as in the above case. Each function of the analyzer 1 of the above-described embodiment and each process of the analysis method will be realized. The computer can also read the program directly from the portable recording medium 108 and execute the process according to the program.

Further, the analysis program for realizing each function of the analyzer 1 of the above-described embodiment or the analysis program for causing the computer to execute each process of the analysis method of the above-described embodiment is, for example, a network as a transmission medium (for example,). It may be provided via the Internet, communication lines such as public lines and dedicated lines).
For example, an analysis program provided by the program provider on another computer such as a server may be installed in the storage device 105 via a network and communication interface such as the Internet or LAN. As a result, the analysis device 1 and the analysis method of the above-described embodiment are realized, and the analysis program installed in the storage device 105 is read and executed by the CPU 102 on the main memory 101 as in the above case. Each function of the analyzer 1 of the above-described embodiment and each process of the analysis method will be realized. Note that the computer can also sequentially execute processing according to the received program each time the program is transferred from another computer such as a server.

Further, here, a single unit having a hardware configuration such as a CPU 102, a memory 101, a communication control unit 109, an input device 106, a display control unit 103, a display device 104, a storage device 105, and a drive device 107 of a portable recording medium 108. The case where the present analyzer 1 is realized as an apparatus has been described as an example, but the present invention is not limited to this. For example, as long as each function of the analyzer 1 and each process of the analysis method of the above-described embodiment are realized, it does not have to be a single device, and even a system composed of a plurality of devices or an integrated device may be used. It may be a system in which processing is performed via a network such as LAN or WAN. For example, a server such as a cloud server is configured to realize each function of the analyzer 1 of the above-described embodiment and each process of the analysis method, and can be used via a computer network such as the Internet or an intranet. Is also good.

Further, here, a case where each function of the analyzer 1 and each process of the analysis method of the above-described embodiment is realized by executing the program read by the CPU 102 on the memory 101 in the computer will be described as an example. However, the present invention is not limited to this, and the OS or the like running on the computer performs a part or all of the actual processing based on the instruction of the program, and each of the analyzers 1 of the above-described embodiment is performed. Each process of the function and the analysis method may be realized. Further, the program (data) read from the portable recording medium 108 and the program (data) provided by the program (data) provider are stored in the function expansion board inserted in the computer or the function expansion unit connected to the computer. After being written to, the CPU provided in the function expansion board or the function expansion unit performs a part or all of the actual processing based on the instruction of the program, and each function of the analyzer 1 of the above-described embodiment and Each process of the analysis method may be realized.

Hereinafter, additional notes will be disclosed with respect to the above-described embodiments and modifications.
(Appendix 1)
Spherical aberration correction A step of reading an atomic resolution image acquired while changing the amount of defocus by a scanning transmission electron microscope and calculating the contrast value of each of a plurality of regions of the atomic resolution image.
This includes a step of associating the position where the contrast value of each of the plurality of regions is maximized with the defocus amount and calculating the amount of distortion occurring in each region of the analysis target corresponding to each of the plurality of regions. An analysis method characterized by that.

(Appendix 2)
The analysis method according to Appendix 1, further comprising a step of setting a range in which the defocus amount is changed based on the peak intensity of an atomic resolution image obtained by changing the focal position positively or negatively.
(Appendix 3)
The analysis method according to Appendix 1 or 2, wherein the step of plotting the position where the contrast value of each of the plurality of regions is maximized and displaying it as a strain amount distribution is included.

(Appendix 4)
A contrast value calculation unit that reads an atomic resolution image acquired while changing the amount of defocus by a spherical aberration correction scanning transmission electron microscope and calculates the contrast value of each of a plurality of regions of the atomic resolution image.
A strain amount calculation unit that calculates the amount of strain generated in each region of the analysis target corresponding to each of the plurality of regions by associating the position where the contrast value of each of the plurality of regions is maximized with the amount of defocus. An analyzer characterized by being provided with.

(Appendix 5)
The analysis according to Appendix 4, further comprising a defocus range setting unit that sets a range in which the defocus amount is changed based on the peak intensity of the atomic resolution image obtained by changing the focal position positively or negatively. apparatus.
(Appendix 6)
The analyzer according to Appendix 4 or 5, further comprising a display control unit that plots a position where the contrast value of each of the plurality of regions is maximized and displays it as a distortion amount distribution.

1 Analyzer 2 Focus adjustment unit 3 Contrast value calculation unit 4 Distortion amount calculation unit 5 Display control unit 6 Electron microscope (Spherical aberration correction scanning transmission electron microscope)
7 Focus change unit 8 Defocus range setting unit 9 Image output unit 101 Memory 102 CPU
103 Display control unit 104 Display device 105 Storage device 106 Input device 107 Drive device 108 Portable recording medium 109 Communication control unit 110 Bus

Claims (4)

Spherical aberration correction A step of reading an atomic resolution image acquired while changing the amount of defocus by a scanning transmission electron microscope and calculating the contrast value of each of a plurality of regions of the atomic resolution image.
This includes a step of associating the position where the contrast value of each of the plurality of regions is maximized with the defocus amount and calculating the amount of distortion occurring in each region of the analysis target corresponding to each of the plurality of regions. An analysis method characterized by that. The analysis method according to claim 1, further comprising a step of setting a range in which the defocus amount is changed based on the peak intensity of the atomic resolution image obtained by changing the focal position positively or negatively. The analysis method according to claim 1 or 2, wherein the step of plotting the position where the contrast value of each of the plurality of regions is maximized and displaying it as a strain amount distribution is included. A contrast value calculation unit that reads the atomic resolution image acquired by changing the defocus amount by a spherical aberration correction scanning transmission electron microscope and calculates the contrast value of each of a plurality of regions of the atomic resolution image.
A strain amount calculation unit that calculates the amount of strain generated in each region of the analysis target corresponding to each of the plurality of regions by associating the position where the contrast value of each of the plurality of regions is maximized with the amount of defocus. An analyzer characterized by being provided with.