JP7030035B2 - Evaluation method of unevenness of element distribution and charged particle beam device - Google Patents

Description

The present invention relates to a method for evaluating unevenness in element distribution and a charged particle beam device.

Each sample is scanned with an electron beam in a charged particle beam device such as a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDS). A technique for obtaining an element map by imaging the difference in the amount of X-ray emission from a point is known (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2017-26478

In the element map, unevenness of the element distribution of the sample can be evaluated. Since the element map is image data, the user must look at the image and judge the unevenness. As described above, the element map could not quantitatively evaluate the unevenness of the element distribution.

One aspect of the method for evaluating unevenness in element distribution according to the present invention is
It is a method of evaluating the unevenness of the element distribution in the element map.
The process of acquiring the element map and
A step of extracting a first island portion in which pixels having a signal intensity equal to or higher than a threshold value are continuously extracted from the element map, and a step of extracting the first island portion.
From the plurality of first islands extracted from the element map, the area of the first island is S, the median area of the first island is Me, and the median absolute deviation of the first island. When is MAD,
S> Me + 2 × MAD
The process of extracting the second island that meets the requirements, and
A step of obtaining the degree of unevenness A of the element distribution from the extracted second island portion using the following equation, and a step of obtaining the degree A of unevenness of the element distribution.
including.

In such an element distribution unevenness evaluation method, the degree of element distribution unevenness can be quantified by obtaining the degree of unevenness A of the element map from the extracted second island portion using the above equation. .. Therefore, in such an element distribution unevenness evaluation method, the element distribution unevenness can be quantitatively evaluated.

One aspect of the method for evaluating unevenness in element distribution according to the present invention is
It is a method of evaluating the unevenness of the element distribution in the element map.
The process of acquiring the element map and
A step of extracting a first island portion in which pixels having a signal intensity equal to or higher than a threshold value are continuously extracted from the element map, and a step of extracting the first island portion.
From the plurality of first islands extracted from the element map, the area of the first island is S, the median area of the first island is Me, and the median absolute deviation of the first island. When is MAD,
S> Me + 2 × MAD
The process of extracting the second island that meets the requirements, and
When the sum of the signal intensities of the pixels constituting the second island portion is set to Int, the step of obtaining the degree of unevenness A of the element distribution from the extracted second island portion using the following equation.
including.

In such an element distribution unevenness evaluation method, the degree of unevenness of the element distribution is obtained in consideration of the signal strength by obtaining the degree of unevenness A of the element map from the extracted second island portion using the above equation. Can be quantified. Therefore, in such an element distribution unevenness evaluation method, the element distribution unevenness can be quantitatively evaluated.

One aspect of the charged particle beam apparatus according to the present invention is
Charged particle beam source and
A deflector that scans the charged particle beam emitted from the charged particle beam source and
A detector that detects a signal emitted from the sample when the sample is irradiated with the charged particle beam, and a detector.
An element map generator that generates an element map by reflecting the signal intensity obtained by detecting the signal from each point of the sample with the detector on the brightness of the pixel corresponding to each point of the sample. ,
Based on the element map, the evaluation unit that evaluates the unevenness of the element distribution and
Including
The evaluation unit
The process of acquiring the element map and
A process of extracting a continuous first island portion of pixels having a signal intensity equal to or higher than a threshold value from the element map.
From the plurality of first islands extracted from the element map, the area of the first island is S, the median area of the first island is Me, and the median absolute deviation of the first island. When is MAD,
S> Me + 2 × MAD
The process of extracting the second island that satisfies the conditions, and
From the extracted second island part, the process of obtaining the degree of unevenness A of the element distribution using the following equation, and
I do.

In such a charged particle beam device, the degree of unevenness in the element distribution can be quantified by obtaining the degree A of unevenness in the element map from the extracted second island portion using the above equation. Therefore, in such a charged particle beam device, the unevenness of the element distribution can be quantitatively evaluated.

One aspect of the charged particle beam apparatus according to the present invention is
Charged particle beam source and
A deflector that scans the charged particle beam emitted from the charged particle beam source and
A detector that detects a signal emitted from the sample when the sample is irradiated with the charged particle beam, and a detector.
An element map generator that generates an element map by reflecting the signal intensity obtained by detecting the signal from each point of the sample with the detector on the brightness of the pixel corresponding to each point of the sample. ,
Based on the element map, the evaluation unit that evaluates the unevenness of the element distribution and
Including
The evaluation unit
The process of acquiring the element map and
A process of extracting a continuous first island portion of pixels having a signal intensity equal to or higher than a threshold value from the element map.
From the plurality of first islands extracted from the element map, the area of the first island is S, the median area of the first island is Me, and the median absolute deviation of the first island. When is MAD,
S> Me + 2 × MAD
The process of extracting the second island that satisfies the conditions, and
When the sum of the signal intensities of the pixels constituting the second island portion is set to Int, the process of obtaining the degree of unevenness A of the element distribution from the extracted second island portion using the following equation is performed.
I do.

In such a charged particle beam device, the degree of unevenness of the element distribution is quantified in consideration of the signal strength by obtaining the degree of unevenness A of the element map from the extracted second island portion using the above equation. can do. Therefore, in such an element distribution unevenness evaluation method, the element distribution unevenness can be quantitatively evaluated.

The flowchart which shows an example of the evaluation method of the unevenness of the element distribution which concerns on 1st Embodiment. The figure which shows an example of the element map M2 schematically. The figure which shows typically the element map M4 obtained by performing the binning treatment. The figure which shows an example of the histogram of the signal strength. The figure for demonstrating the method of finding a threshold value. The figure which shows typically the binary image M6 obtained by binarizing the element map M4. The figure which shows typically the binary image M8 which shows the result of extracting an island part. The figure for demonstrating the process of obtaining the unevenness degree of an element map M2. The flowchart which shows an example of the evaluation method of the unevenness of element distribution which concerns on 2nd Embodiment. The figure which shows the structure of the scanning electron microscope which concerns on 3rd Embodiment.

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.

1. 1. First Embodiment First, the method of evaluating the unevenness of the element distribution according to the first embodiment will be described with reference to the drawings. FIG. 1 is a flowchart showing an example of an evaluation method of element distribution unevenness according to the first embodiment.

1.1. Acquisition of element map (S100)
FIG. 2 is a diagram schematically showing an example of the element map M2. In the element map M2, for example, in a scanning electron microscope (SEM), the sample is scanned with an electron beam to detect X-rays from each point of the sample, and the intensity of X-rays peculiar to the element is applied to each point of the sample. It is obtained by reflecting on the brightness of the corresponding pixel. The element map M2 is, for example, an element map obtained by detecting characteristic X-rays emitted from a sample with an energy dispersive X-ray detector (hereinafter, also referred to as “EDS detector”).

The element map M2 is composed of a plurality of pixels. The luminance value of the pixel corresponds to the intensity of X-rays peculiar to the element, that is, the signal intensity. The higher the signal strength of the pixels constituting the element map M2, the larger the luminance value. The signal strength is, for example, the number of X-rays detected by the X-ray detector, that is, the number of counts. The count number is expressed as, for example, the number of X-rays detected by the detector per second, that is, the count rate (unit: cps (counts per second)).

1.2. Binning process (S102)
Next, binning processing is performed on the element map M2. FIG. 3 is a diagram schematically showing an element map M4 obtained by performing a binning process on the element map M2.

For example, by adding the signal intensities of four adjacent images and performing 2 × 2 binning, the four adjacent pixels of the element map M2 can be treated as one pixel.

Although the case where four pixels are treated as one pixel has been described here, the unit for performing the binning process (the number of pixels regarded as one pixel) is not particularly limited. In this step, for example, a 4 × 4 binning process may be performed, or a binning process may be performed in units larger than that.

Further, for example, in the element map M2, when the signal strength is sufficiently obtained, the binning process may not be performed.

1.3. Extraction of islands (first island) (S104)
Next, the island I2 (see FIG. 6) is extracted from the element map M4. The island portion I2 is a portion of the element map M4 in which pixels having a signal intensity equal to or higher than a threshold value are continuous. The extraction of the island part I2 is performed, for example, by binarizing the element map M4.

FIG. 4 is a diagram showing an example of a histogram of the signal intensity of the element map M4. In the signal strength histogram shown in FIG. 4, the horizontal axis represents the signal strength of the pixels constituting the element map M4, and the vertical axis represents the number of pixels (frequency).

For example, when a sample is damaged by irradiation with an electron beam such as an organic substance, it may not be possible to take sufficient measurement time to acquire an elemental map. In such a case, the statistical error becomes large, and as shown in FIG. 4, the signal intensity histogram has a distribution with one peak. As described above, when the statistical error is large, it is often impossible to set an appropriate threshold value even if a discriminant analysis method or the like is used as a binarization method.

Here, where the island portion I2 is located, the signal strength becomes large. Therefore, in the first embodiment, the island portion I2 is extracted by dividing the pixels into pixels having an average signal intensity and pixels having a signal intensity higher than the average. Specifically, the sum of the average value of the signal intensities of the pixels constituting the element map M4 and the dispersion of the signal intensities of the pixels constituting the element map M4 is set as the threshold value. The variance of the signal strength is used as an allowable value.

FIG. 5 is a diagram for explaining a method for obtaining a threshold value.

When the average value of the signal strengths of the pixels constituting the element map M4 is Ave, the variance of the signal strengths of the pixels constituting the element map M4 is V, and the coefficient is K, the threshold value T is set.
T = Ave + K × V
Can be obtained at.

When K = 1, it means that the permissible value is 1σ (sigma). Similarly, when K = 2, the permissible value is 2σ, and when K = 3, the permissible value is 3σ.

By obtaining the threshold value T in this way, the threshold value T can be set to an appropriate value even when the histogram of the signal strength has one distribution of peaks, that is, even when the statistical error is large. ..

FIG. 6 is a diagram schematically showing a binary image M6 obtained by binarizing the element map M4.

A binary image M6 can be obtained by binarizing the element map M4 using the threshold value T. In the binary image M6, the pixels having the signal intensity of the threshold value T or more are represented by white, and the pixels having the signal intensity of less than the threshold value T are represented by black.

The island portion I2 (first island portion) can be extracted by extracting a region in which white pixels are continuous from the binary image M6. The island portion I2 is a portion where pixels having a signal intensity of equal to or higher than the threshold value T are continuous.

In the above binning process (S102) and the process of extracting the island portion I2 using the threshold value T (S104), the number of pixels regarded as one pixel in the binning process and the value of the coefficient K are changed. It may be performed multiple times to search for the optimum value.

1.4. Extraction of islands (second island) (S106)
Next, the island part I4 (second island part) is extracted from the extracted plurality of island parts I2.

The extraction of the island I4 is performed, for example, by discriminating the abnormal value using Sprent's non-parametric method, which finds an abnormal value based on the median of the area of the island I2. Will be done. The median, unlike the mean, is less dependent on outliers.

Specifically, from the extracted multiple islands I2,
S> Me + 2 × MAD ・ ・ ・ (1)
The island part I2 that satisfies the condition is extracted and used as the island part I4. However, S is the area of the island I2. Me is the median area of the island I2. MAD is the median absolute deviation of Shimabe I2. In this way, the area of the island I2 is discriminated from an abnormal value, and the island I4 is extracted.

In the example shown in FIG. 6, since there are five islands I2, first, the median Me of the areas of the five islands I2 and the median absolute deviation MAD of the areas of the five islands I2 are obtained. Next, it is examined whether or not the above equation (1) is satisfied for each of the five islands I2. In the binary image M6 shown in FIG. 6, the island portion I2 that does not satisfy the above formula (1) is removed, and the island portion I2 that satisfies the above formula (1) is left to extract the island portion I4.

FIG. 7 is a diagram schematically showing a binary image M8 showing the result of extracting the island portion I4.

In FIG. 7, the small island portion I2 seen in the binary image M6 shown in FIG. 6 is removed, and the large island portion I2 remains as the island portion I4. In this way, the island portion I4 constituting the unevenness of the element distribution is extracted.

1.5. Calculation of unevenness (S108)
Next, from the extracted island portion I4, the degree of unevenness A (hereinafter, also referred to as “unevenness degree A”) of the element distribution in the element map M2 is obtained by using the following equation.

For example, for any one island I4, the area S is divided by Me + 2 × MAD. This is done for all the extracted islands I4, and the sum of the obtained values is calculated.

FIG. 8 is a diagram for explaining a step (S108) for obtaining the unevenness degree A in the element map M2. FIG. 8 corresponds to the binary image M8 shown in FIG. In FIG. 8, the three islands I4 extracted in step S106 are represented as islands I4a, islands I4b, and islands I4c.

In step S108, first, the area S _I4a of the island portion I4a is divided by Me + 2 × MAD to obtain the unevenness degree A _I4a of the island portion I4a.

Similarly, the unevenness degree A I4b of the island part I4b and the unevenness degree A _I4c of the island part _I4c are obtained.

However, _SI4b is the area of the island portion I4b, and _SI4c is the area of the island portion I4c.

Next, the sum of the unevenness A _{I4a of the island I4a, the unevenness A I4b} of the island _I4b , and the unevenness A _I4c of the island I4c is obtained, and the unevenness A in the element map M2 is obtained.

By the above steps, the degree of unevenness A in the element map M2 can be obtained. In this way, in the first embodiment, the degree of unevenness of the element distribution in the element map M2 can be quantified.

The degree of unevenness A means that the larger the numerical value, the larger the unevenness of the element distribution. For example, in the element map M2, it is assumed that there is no unevenness when the unevenness degree A is 2 or less (A ≦ 2), and there is a little unevenness when the unevenness degree A is larger than 2 and smaller than 10 (2 <A ≦ 10). When the degree of unevenness A is larger than 10 (A> 10), it may be assumed that the unevenness is large and the unevenness of the element distribution may be evaluated.

1.6. Features The method for evaluating the unevenness of the element distribution according to the first embodiment has, for example, the following features.

In the method for evaluating the unevenness of the element distribution according to the first embodiment, the islands I4 satisfying the above formula (1) are extracted from the plurality of islands I2 extracted from the element map M2, and the above-mentioned islands I4 are extracted from the extracted islands I4. The degree of unevenness A in the element map M2 is obtained by using the formula (2). Therefore, in the method for evaluating the unevenness of the element distribution according to the first embodiment, the degree of the unevenness of the element distribution in the element map M2 can be quantified. Therefore, in the method for evaluating the unevenness of the element distribution according to the first embodiment, the unevenness of the element distribution can be quantitatively evaluated.

As a result, for example, it is possible to easily compare the unevenness of the element distribution between different samples. Further, by quantifying the degree of unevenness of the element distribution, even when the sample is an organic substance weak to an electron beam and the signal intensity cannot be sufficiently obtained, the comparison between the samples can be easily performed.

In the method for evaluating the unevenness of the element distribution according to the first embodiment, in the step of extracting the island portion I2, the average value of the signal intensities of the pixels constituting the element map M4 is set to Ave, and the signal of the pixels constituting the element map M4 is set. When the variance of the intensity is V and the coefficient is K, the threshold T is set to
T = Ave + K × V
And. Therefore, in the method for evaluating the unevenness of the element distribution according to the first embodiment, the threshold value T can be set to an appropriate value even when the statistical error is large. Therefore, for example, the island portion I2 can be extracted even when the sample is an organic substance weak to an electron beam and the signal strength cannot be sufficiently obtained.

2. 2. Second Embodiment Next, the method of evaluating the element distribution according to the second embodiment will be described.

In the method for evaluating the unevenness of the element distribution according to the first embodiment described above, the degree of unevenness A in the element map M2 was obtained by using the above formula (2). Here, the method for evaluating the unevenness of the element distribution according to the first embodiment is the evaluation based on the area S of the island portion I4 as shown in the above formula (2), and the signal strength is not taken into consideration.

Therefore, in the element distribution evaluation method according to the second embodiment, the unevenness of the element distribution is evaluated in consideration of the signal strength.

FIG. 9 is a flowchart showing an example of the method for evaluating the unevenness of the element distribution according to the second embodiment.

2.1. Acquisition of element map (S200)
First, the element map M2 shown in FIG. 2 is acquired. The step (S200) for acquiring the element map M2 is performed in the same manner as in step S100 shown in FIG.

2.2. Binning process (S202)
Next, binning processing is performed on the element map M2. As a result, the element map M4 shown in FIG. 3 can be obtained. The step of performing the binning process (S202) is performed in the same manner as in step S102 shown in FIG.

2.3. Extraction of islands (first island) (S204)
Next, the island portion I2 is extracted using the threshold value T = Ave + K × V. Specifically, the element map M4 is binarized using the threshold value T to extract the island portion I2. As a result, the binary image M6 shown in FIG. 6 is obtained. The step (S204) for extracting the island portion I2 is performed in the same manner as in step S104 shown in FIG.

2.4. Extraction of islands (second island) (S206)
Next, the island portion I4 satisfying the above formula (1) is extracted from the plurality of island portions I2 extracted from the binary image M6. The step (S206) for extracting the island portion I4 is performed in the same manner as in step S106 shown in FIG.

2.5. Calculation of unevenness (S208)
Next, the degree of unevenness A in the element map M2 is obtained from the extracted island portion I4.

Specifically, when the sum of the signal intensities of the pixels constituting the island portion I4 is set to Int, the degree of unevenness A in the element map M2 is obtained from the extracted island portion I4 by using the following equation.

The sum of signal intensities Int is a value normalized by the average value of the signal intensities of the pixels constituting all the extracted island portions I4.

In the step (S208) of obtaining the unevenness degree A, first, the average value of the signal intensities of the pixels constituting all the extracted island portions I4 is obtained.

In the example shown in FIG. 8, three islands I4 are extracted. The number of pixels of the island portion I4a is 13, the number of pixels of the island portion I4b is 4, and the number of pixels of the island portion I4c is 33. That is, the number of pixels constituting all the extracted islands I4 is 50. The average value of the signal intensities of these 50 pixels is obtained.

Next, the intensity of each pixel constituting the island portion I4 is standardized by the average value of the signal intensities of the obtained pixels. In the example shown in FIG. 8, the signal strength of each of the 50 pixels is divided by the obtained average value and normalized.

Next, for any one island portion I4, the sum of the signal strengths (normalized signal strengths) of the pixels constituting the island portion I4 is obtained. Thereby, the sum Int of the signal strength in the island part I4 can be obtained. Next, the area S of the island portion I4 is multiplied by the sum of Int of the obtained signal strengths and divided by Me + 2 × MAD. This process is performed on all the extracted islands I4, and the sum is calculated.

In the example shown in FIG. 8, first, the sum of the signal intensities (normalized signal intensities) of the 13 pixels constituting the island portion I4a is obtained, and the sum of the signal intensities in the island portion I4a, Int _I4a , is obtained. Next, the area S _I4a of the island portion I4a is multiplied by the sum of the obtained signal strengths Int _I4a and divided by Me + 2 × MAD to obtain the unevenness degree A _I4a of the island portion I4a.

Similarly, the unevenness degree A I4b of the island part I4b and the unevenness degree A _I4c of the island part _I4c are obtained.

However, Int _I4b is the sum of the signal strengths in the island portion I4a, and Int _I4c is the sum of the signal strengths in the island portion I4c.

Next, the sum of the unevenness degree A I4a of the island part I4a, the unevenness degree A _I4b of the island part I4b, and the unevenness degree A _I4c of the island part _I4c is calculated, and the unevenness degree A in the element map M2 is obtained.

By the above steps, the degree of unevenness A in the element map M2 can be obtained.

The degree of unevenness A means that the larger the numerical value, the more uneven the element distribution. For example, in the element map M2, it is assumed that there is no unevenness when the unevenness degree A is 10 or less (A ≦ 10), and there is a little unevenness when the unevenness degree A is larger than 10 and smaller than 20 (10 <A ≦ 20). When the degree of unevenness A is larger than 20, (A> 20), the unevenness may be considered to be large, and the unevenness of the element distribution may be evaluated.

2.6. Features The method for evaluating the unevenness of the element distribution according to the second embodiment has, for example, the following features.

In the method for evaluating the unevenness of the element distribution according to the second embodiment, the islands I4 satisfying the above formula (1) are extracted from the plurality of islands I2 extracted from the element map M2, and the above-mentioned islands I4 are extracted from the extracted islands I4. The degree of unevenness A in the element map M2 is obtained by using the formula (3). Therefore, in the method for evaluating the unevenness of the element distribution according to the second embodiment, the degree of the unevenness in the element distribution can be quantified in the same manner as the method for evaluating the unevenness of the element distribution according to the first embodiment.

Further, in the method for evaluating the unevenness of the element distribution according to the second embodiment, as shown in the above equation (3), the degree of the unevenness of the element distribution in the element map M2 can be quantified in consideration of the signal strength. can. Therefore, for example, even if the island portion I4 has the same area, the degree of unevenness A is higher when there is an island portion I4 having a high X-ray intensity than when there is an island portion I4 having a low X-ray intensity. growing. As described above, in the method for evaluating the unevenness of the element distribution according to the second embodiment, the degree of the unevenness of the element distribution can be quantified in consideration of the intensity of X-rays. Therefore, the degree of unevenness in the element distribution can be quantified more accurately.

In the method for evaluating the unevenness of the element distribution according to the second embodiment, the sum Int of the signal intensities is a value standardized by the average value of the signal intensities of the pixels constituting all the extracted islands I2. Therefore, for example, even when the measurement times of the two element maps M2 are significantly different and the signal intensities are different, it is possible to compare the unevenness of the element distribution between the two element maps M2.

3. 3. Third Embodiment 3.1. Scanning electron microscope Next, the scanning electron microscope according to the third embodiment will be described with reference to the drawings. FIG. 10 is a diagram showing the configuration of the scanning electron microscope 100 according to the third embodiment. Hereinafter, as the charged particle beam apparatus according to the present invention, a scanning electron microscope that scans a sample with an electron beam to acquire an element map will be described as an example, but the charged particle beam apparatus according to the present invention is other than an electron beam. It may be a device for acquiring an element map by scanning a sample with a charged particle beam (ion beam or the like) of.

As shown in FIG. 10, the scanning electron microscope 100 includes an electron source 10 (an example of a charged particle beam source), a condenser lens 12, an objective lens 14, a deflector 16, a sample stage 20, and secondary electron detection. It includes a device 30, an X-ray detector 40, a signal processing unit 50, a processing unit 60, an operation unit 70, a display unit 72, and a storage unit 74.

The electron source 10 generates electrons. The electron source 10 is, for example, an electron gun that accelerates electrons emitted from a cathode by an anode and emits an electron beam EB.

The condenser lens 12 focuses the electron beam EB emitted from the electron source 10. The diameter of the electron beam EB and the amount of current of the electron beam EB can be controlled by the condenser lens 12.

The objective lens 14 is arranged immediately before the sample 2. The objective lens 14 focuses the electron beam EB to form an electron probe. The objective lens 14 includes, for example, a coil and a yoke. In the objective lens 14, the magnetic axis lines made by the coil are confined in a yoke made of a material having high magnetic permeability such as iron, and a notch (lens gap) is made in a part of the yoke to distribute the magnetic force at high density. Leakage of magnetic field lines on the optical axis.

The deflector 16 deflects the electron beam EB two-dimensionally. By inputting a scanning signal to the deflector 16, the sample 2 can be scanned with an electron beam EB (electron probe).

The sample stage 20 can support the sample 2. The sample stage 20 is configured to include a moving mechanism for moving the sample 2. By moving the sample 2 on the sample stage 20, the position on the sample 2 where the electron beam EB is irradiated can be moved.

The secondary electron detector 30 detects the secondary electrons emitted from the sample 2. The output signal of the secondary electron detector 30 is associated with the information of the irradiation position of the electron beam EB specified by the scanning signal, and is stored in a storage device (not shown). As a result, a secondary electron image (SEM image) can be obtained.

The X-ray detector 40 detects characteristic X-rays generated from the sample 2 when the electron beam EB irradiates the sample 2. The X-ray detector 40 is, for example, a silicon drift detector (SDD).

The signal processing unit 50 includes, for example, a multi-channel analyzer. The signal processing unit 50 analyzes the energy value based on the pulse peak value of the electric signal output from the X-ray detector 40, performs processing for allocating the corresponding channel, and X-rays detected by the X-ray detector 40. Is counted for each energy. Thereby, the count number (counting rate) of X-rays peculiar to the element, that is, the signal strength can be obtained.

The operation unit 70 performs a process of converting an instruction from the user into a signal and sending it to the processing unit 60. The operation unit 70 can be realized by an input device such as a button, a key, a trackball, a touch panel type display, and a microphone.

The display unit 72 outputs the image generated by the processing unit 60. The display unit 72 can be realized by, for example, a display such as an LCD (liquid crystal display).

The storage unit 74 stores programs and data for the processing unit 60 to perform various calculation processes and control processes. The storage unit 74 is also used as a work area of the processing unit 60. The storage unit 74 can be realized by, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), a hard disk, or the like.

The processing unit 60 performs processing such as processing for generating an element map and processing for obtaining the degree of unevenness of the element distribution in the element map. The function of the processing unit 60 can be realized by executing a program on various processors (CPU (Central Processing Unit) or the like). The processing unit 60 includes an element map generation unit 62 and an evaluation unit 64.

The element map generation unit 62 performs a process of generating the element map M2 shown in FIG. The element map generation unit 62 reflects the signal intensity obtained by detecting the X-rays from each point of the sample 2 with the X-ray detector 40 in the brightness of the pixels corresponding to each point of the sample 2 to be an element. Generate map M2.

The evaluation unit 64 evaluates the degree of unevenness in the element distribution based on the element map M2. The evaluation unit 64 acquires the element map M2 generated by the element map generation unit 62, and obtains the degree of unevenness of the element distribution in the element map M2. The evaluation unit 64 obtains the degree of unevenness A by using the method for evaluating the unevenness of the element distribution according to the first embodiment described above. Specifically, the evaluation unit 64 performs a process of acquiring an elemental map, a process of performing a binning process on the elemental map, and an island portion I2 in which pixels having an X-ray intensity of the threshold T or more are continuous from the elemental map. The process of extracting, the process of extracting the islands I4 satisfying the above formula (1) from the plurality of islands I2 extracted from the element map, and the process of extracting the extracted islands I4 from the extracted islands I4 using the above formula (2). The process of obtaining the degree A and the process are performed.

As described above, in the scanning electron microscope 100, the evaluation unit 64 obtains the unevenness degree A by using the method for evaluating the unevenness of the element distribution according to the first embodiment described above. Therefore, in the scanning electron microscope 100, the degree of unevenness of the element distribution in the element map can be quantified.

3.2. Modification Example In the above, the case where the evaluation unit 64 obtains the unevenness degree A by using the method for evaluating the unevenness of the element distribution according to the first embodiment described above has been described, but the evaluation unit 64 has described the above-mentioned first. 2. The degree of unevenness A may be obtained by using the method for evaluating the unevenness of the element distribution according to the second embodiment. In this case, the evaluation unit 64 extracts from the element map a process of acquiring an element map, a process of performing a binning process on the element map, and an island portion I2 in which pixels having an X-ray intensity equal to or higher than a threshold value are continuous. The process, the process of extracting the islands I4 satisfying the above formula (1) from the plurality of islands I2 extracted from the element map, and the process of extracting the extracted islands I4 from the extracted islands I4 using the above formula (3) to achieve the degree of unevenness A. And the process of finding. In this case as well, the scanning electron microscope 100 can quantify the degree of unevenness of the element distribution in the element map, as in the above example.

Further, in the above, the case where the charged particle beam device according to the present invention is a scanning electron microscope has been described, but the charged particle beam device according to the present invention scans the sample 2 with the charged particle beam and acquires an element map. Any device that can be used will do. The charged particle beam apparatus according to the present invention may be, for example, a scanning transmission electron microscope or an electron probe microanalyzer.

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 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 ... sample, 10 ... electron source, 12 ... condenser lens, 14 ... objective lens, 16 ... deflector, 20 ... sample stage, 30 ... secondary electron detector, 40 ... X-ray detector, 50 ... signal processing unit, 60 ... Processing unit, 62 ... Element map generation unit, 64 ... Evaluation unit, 70 ... Operation unit, 72 ... Display unit,
74 ... Storage unit, 100 ... Scanning electron microscope

Claims (6)

It is a method of evaluating the unevenness of the element distribution in the element map.
The process of acquiring the element map and
A step of extracting a first island portion in which pixels having a signal intensity equal to or higher than a threshold value are continuously extracted from the element map, and a step of extracting the first island portion.
From the plurality of first islands extracted from the element map, the area of the first island is S, the median area of the first island is Me, and the median absolute deviation of the first island. When is MAD,
S> Me + 2 × MAD
The process of extracting the second island that meets the requirements, and
A step of obtaining the degree of unevenness A of the element distribution from the extracted second island portion using the following equation, and a step of obtaining the degree A of unevenness of the element distribution.
A method for evaluating unevenness in element distribution, including.

It is a method of evaluating the unevenness of the element distribution in the element map.
The process of acquiring the element map and
A step of extracting a first island portion in which pixels having a signal intensity equal to or higher than a threshold value are continuously extracted from the element map, and a step of extracting the first island portion.
From the plurality of first islands extracted from the element map, the area of the first island is S, the median area of the first island is Me, and the median absolute deviation of the first island. When is MAD,
S> Me + 2 × MAD
The process of extracting the second island that meets the requirements, and
When the sum of the signal intensities of the pixels constituting the second island portion is set to Int, the step of obtaining the degree of unevenness A of the element distribution from the extracted second island portion using the following equation.
A method for evaluating unevenness in element distribution, including.

In claim 2,
The sum Int of the signal intensities is a value standardized by the average value of the signal intensities of all the extracted pixels constituting the second island portion, and is a method for evaluating unevenness of element distribution. In any one of claims 1 to 3,
The step of extracting the first island portion is
When the average value of the signal strengths of the pixels constituting the element map is Ave, the dispersion of the signal strengths of the pixels constituting the element map is V, and the coefficient is K, the threshold value T is set.
T = Ave + K × V
How to evaluate the unevenness of the element distribution. Charged particle beam source and
A deflector that scans the charged particle beam emitted from the charged particle beam source and
A detector that detects a signal emitted from the sample when the sample is irradiated with the charged particle beam, and a detector.
An element map generator that generates an element map by reflecting the signal intensity obtained by detecting the signal from each point of the sample with the detector on the brightness of the pixel corresponding to each point of the sample. ,
Based on the element map, the evaluation unit that evaluates the unevenness of the element distribution and
Including
The evaluation unit
The process of acquiring the element map and
A process of extracting a continuous first island portion of pixels having a signal intensity equal to or higher than a threshold value from the element map.
From the plurality of first islands extracted from the element map, the area of the first island is S, the median area of the first island is Me, and the median absolute deviation of the first island. When is MAD,
S> Me + 2 × MAD
The process of extracting the second island that satisfies the conditions, and
From the extracted second island part, the process of obtaining the degree of unevenness A of the element distribution using the following equation, and
A charged particle beam device.

Charged particle beam source and
A deflector that scans the charged particle beam emitted from the charged particle beam source and
A detector that detects a signal emitted from the sample when the sample is irradiated with the charged particle beam, and a detector.
An element map generator that generates an element map by reflecting the signal intensity obtained by detecting the signal from each point of the sample with the detector on the brightness of the pixel corresponding to each point of the sample. ,
Based on the element map, the evaluation unit that evaluates the unevenness of the element distribution and
Including
The evaluation unit
The process of acquiring the element map and
A process of extracting a continuous first island portion of pixels having a signal intensity equal to or higher than a threshold value from the element map.
From the plurality of first islands extracted from the element map, the area of the first island is S, the median area of the first island is Me, and the median absolute deviation of the first island. When is MAD,
S> Me + 2 × MAD
The process of extracting the second island that satisfies the conditions, and
When the sum of the signal intensities of the pixels constituting the second island portion is set to Int, the process of obtaining the degree of unevenness A of the element distribution from the extracted second island portion using the following equation is performed.
A charged particle beam device.

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