JP6915374B2 - X-ray analysis method and X-ray analyzer - Google Patents

Description

The present invention relates to an X-ray analysis method and an X-ray analyzer.

As a method for analyzing the internal structure of a sample or the like, there are an X-ray CT (X-ray Computed Tomography) method and an X-ray laminography method.

The X-ray CT method irradiates a sample to be analyzed with X-rays, acquires projected images from various directions of the sample while rotating the in-plane rotation angle Φ of the sample, and analyzes the projected images. This is an analysis method for acquiring a tomographic image of a sample (for example, Non-Patent Document 1). Various improved devices and methods have been proposed for the X-ray CT method (for example, Patent Document 1), and they are often used for medical purposes. This is because the X-ray CT method is good at cylindrical or spherical samples in which the transmission and absorption of X-rays are uniform with respect to the rotation of the sample, and the medical use often has the above-mentioned shape like the human body. Can be mentioned. On the other hand, in the electrical and electronic industries, many of the samples to be analyzed are flat-shaped samples such as printed circuit boards, which are not good at the X-ray CT method, so their use is not as advanced as for medical use. ..

Therefore, an X-ray laminography method has been proposed as a tomographic image acquisition method for a flat plate-shaped sample, which the X-ray CT method is not good at (for example, Non-Patent Document 2). In both the X-ray CT method and the X-ray laminography method, the sample is irradiated with X-rays, and the in-plane rotation angle Φ of the sample is rotated to obtain projected images from various directions of the sample. The point that the tomographic image of the sample is obtained by analyzing the projected image is the same. The difference between the X-ray CT method and the X-ray laminography method is that in the X-ray laminography method, the sample to be analyzed is tilted in the direction of the X-ray source (sample tilt angle ψ direction). , It is a point that is not tilted by the X-ray CT method (ψ = 0 °).

Japanese Unexamined Patent Publication No. 3-209119 Special Table 2009-505083 Special Table 2016-533481

G. N. Hounsfield,'Computerized transverse axial scanning (tomography). 1. 1. Description of system. ’British Journal of Radiology 46, 1016 (1973). S. Gondrom et al. ’X-ray computed tomography: an approach of computed tomography for applications with limited access’ 190, 141 (1999). L. Helfen et al. ’On the implementation of computed laminography using synchrotron radiation’ 82, 063702 (2011).

As described above, in the X-ray laminography method, the sample is rotated and analyzed in a state of being tilted at the set sample tilt angle ψ. In the analysis by the actual X-ray laminography method, the sample inclination angle ψ is the most among the sample tomographic images obtained by selecting, for example, three levels based on past experience and measuring under the conditions of these three levels. The good one was used as the sample tomographic image of the sample. Specifically, the sample tilt angle ψ is _{selected from three levels of ψ N} -10 °, ψ _N , and ψ _N + 10 °, sample tomographic images are obtained for each sample tilt angle ψ, and the best one is obtained. Was used as the sample tomographic image of the sample. The level selected for the sample inclination angle ψ may be 5 levels or higher.

More specifically, when obtaining a sample tomographic image by the X-ray laminography method, first, the sample position is adjusted. Specifically, while checking the sample projection image, the translational X-axis and the translational Y-axis are adjusted so that the sample is irradiated with X-rays, and further tilted so that the outer shape of the sample and the inclination of the irradiated X-rays are eliminated. Adjust the Rx axis and the tilt Ry axis. Next, at the selected sample inclination angle ψ, the sample rotation angle Φ is rotated from 0 ° to 360 °, and for example, 3600 sample projection images are acquired every 0.1 °. Next, the sample tomographic image can be obtained by analyzing the sample projection image by the filtered back projection (FBP) method in consideration of the inclination.

When the sample inclination angle ψ is set to three levels as described above, each sample tomographic image is acquired by performing the above steps at each sample inclination angle ψ. After that, the best one is selected as the sample tomographic image of the sample from the obtained three sample tomographic images.

By the way, in the X-ray laminography method, the sample tilt angle ψ has a very large effect on the image quality of the sample tomographic image. It takes a lot of time. In particular, if the measurer is not skilled, the number of levels of the sample inclination angle ψ increases, so that further time is required. In addition, since the best sample tomographic image is selected from the sample tomographic images obtained by the set multiple sample inclination angles ψ, the obtained sample tomographic image is not the best sample tomographic image of the sample, but more. A good sample tomographic image may be obtained.

Therefore, there has been a demand for an X-ray analysis method capable of obtaining a better sample tomographic image in a short time.

According to one aspect of the present embodiment, a sample is placed in a sample setting portion, the sample is irradiated with X-rays from an X-ray source, and a two-dimensional image of X-rays transmitted through the sample is transmitted by an X-ray detector. In the X-ray analysis method for detection, the relationship between the in-plane rotation angle Φ of the sample and the X-ray transmission rate transmitted through the sample is determined by measuring the transmission rate of the X-ray transmitted through the sample while rotating the sample. Based on the relationship between the obtaining step and the obtained in-plane rotation angle Φ of the sample and the X-ray transmission rate, the _{step of obtaining the in-plane rotation angle Φ N} of the sample having the minimum X-ray transmission rate and the in-plane rotation of the sample. A step of obtaining a relationship between the sample inclination angle ψ and the X-ray transmission rate transmitted through the sample by measuring the transmission rate of X-rays transmitted through the sample while tilting the sample in a state of an angle Φ _N. obtained based on the relationship between the specimen rotation angle [psi and X-ray transmittance, the step of selecting a specimen rotation angle [psi _N such that a predetermined X-ray transmittance T _S, the specimen rotation angle the sample [psi A step of acquiring a two-dimensional sample projection image of the sample by detecting X-rays transmitted through the sample while rotating the sample in a state of being tilted at _{N, and the acquired sample projection image.} Based on this, it is characterized by having a step of obtaining a tomographic image of the sample.

According to the disclosed X-ray analysis method, a good sample tomographic image can be obtained in a short time.

Structural diagram of the X-ray analyzer according to the first embodiment Flow chart of the X-ray analysis method in the first embodiment Correlation diagram of the in-plane rotation angle Φ of the sample 100A and the X-ray transmittance T Correlation diagram of sample inclination angle ψ and X-ray transmittance T in sample 100A Correlation diagram of the in-plane rotation angle Φ of the sample and the X-ray transmittance T when the sample inclination angle ψ is changed. Correlation diagram between the sample inclination angle ψ and the X-ray transmittance T when the in-plane rotation angle Φ of the sample is changed. Explanatory drawing of data loss rate (1) Explanatory drawing of data loss rate (2) Explanatory drawing of data loss rate (3) Correlation diagram of sample inclination angle ψ and data loss rate L in sample 100A Flow chart of the X-ray analysis method in the second embodiment Correlation diagram of the in-plane rotation angle Φ of the sample 100B and the X-ray transmittance T Correlation diagram of sample inclination angle ψ and X-ray transmittance T in sample 100B Correlation diagram of sample inclination angle ψ and data loss rate L in sample 100B Correlation diagram of the in-plane rotation angle Φ of the sample 100C and the X-ray transmittance T Correlation diagram of sample inclination angle ψ and X-ray transmittance T in sample 100C Correlation diagram between sample inclination angle ψ and data loss rate L in sample 100C

A mode for carrying out the invention will be described below. The same members and the like are designated by the same reference numerals and the description thereof will be omitted.

[First Embodiment]
(X-ray analyzer)
The X-ray analyzer according to the first embodiment will be described. As shown in FIG. 1, the X-ray analyzer according to the present embodiment includes an X-ray source 10, an X-ray detector 20, a sample installation unit 30 on which a sample is installed, a control unit 50, and the like.

The X-rays generated at the X-ray source 10 irradiate the sample 100 to be analyzed installed on the sample table 31 in the sample setting unit 30. The X-rays generated at the X-ray source 10 may be white X-rays, monochromatic X-rays separated by a monochromatic device, parallel X-rays, or divergent X-rays.

The X-ray detector 20 is a two-dimensional detector that detects a two-dimensional image of X-rays that have passed through the sample 100, and obtains a sample projection image based on the X-rays detected by the X-ray detector 20. Obtainable. The sample setting unit 30 includes a translation X-axis adjustment stage 32, a translation Y-axis adjustment stage 33, an inclination Rx-axis adjustment stage 34, an inclination Ry-axis adjustment stage 35, a sample in-plane rotation angle Φ stage 36, and a sample inclination angle ψ adjustment stage 37. Etc.

The position and inclination of the sample to be analyzed installed on the sample table 31 are adjusted by the translation X-axis adjustment stage 32, the translation Y-axis adjustment stage 33, the inclination Rx-axis adjustment stage 34, and the inclination Ry-axis adjustment stage 35. be able to.

The sample in-plane rotation angle Φ stage 36 rotates the sample to be analyzed installed on the sample table 31, and by rotating the sample in-plane rotation angle Φ stage 36, various orientations of the sample are obtained. A sample projection image from can be obtained. The sample tilt angle ψ adjustment stage 37 is for obtaining a higher quality sample tomographic image, and the sample tilt angle ψ adjustment stage 37 is set to a desired sample tilt angle ψ for measurement.

The control unit 50 controls the X-ray analyzer according to the present embodiment, and the control unit 50 includes an analysis unit 51 that performs analysis and calculations related to the X-ray analysis method according to the present embodiment. It is provided.

(X-ray analysis method)
Next, the X-ray analysis method in the present embodiment will be described. The X-ray analysis method in the present embodiment can obtain a good sample tomographic image in a short time in the X-ray laminography method. Specifically, a good sample tomographic image can be obtained in a short time by selecting a sample inclination angle ψ that can obtain an optimum sample tomographic image and obtaining a sample tomographic image from the sample incline angle ψ. It is a thing.

The X-ray analysis method in the present embodiment will be described with reference to the flowchart shown in FIG. The control and the like in the X-ray analysis method in the present embodiment are performed by the control unit 50. Further, the X-rays generated by the X-ray source 10 are monochromatic and parallel X-rays of 30 keV. In the present embodiment, the case where the sample 100 to be analyzed is a sample 100A which is a Si chip having a size of 5 mm × 10 mm and a thickness of 0.5 mm will be described.

First, in step 102 (S102), the position of the sample 100A to be analyzed installed on the sample table 31 is adjusted. Specifically, the translation target sample 100A installed on the sample table 31 by the translation X-axis adjustment stage 32, the translation Y-axis adjustment stage 33, the tilt Rx-axis adjustment stage 34, and the tilt Ry-axis adjustment stage 35. The translation X-axis, translation Y-axis, tilt Rx-axis, and tilt Ry-axis are adjusted. In this adjustment, the translation X-axis, translation Y-axis, tilt Rx-axis, and tilt Ry-axis of the sample 100A are adjusted so that the center line of the sample 100A to be analyzed coincides with the rotation axis of the in-plane rotation angle Φ of the sample. I do.

Next, in step 104 (S104), measurement is performed to obtain the relationship between the sample in-plane rotation angle Φ and the X-ray transmittance T. Specifically, the X-ray transmittance T of the sample 100A is measured by rotating the sample in-plane rotation angle Φ stage 36 in the range of −90 ° ≦ Φ <90 °. The X-ray transmission T can be measured by using the X-ray detector 20, and an X-ray detector for measuring the X-ray transmission T is provided separately from the X-ray detector 20. The measurement may be performed by an X-ray detector. The relationship between the in-plane rotation angle Φ of the sample thus obtained and the X-ray transmittance T is shown in FIG. This relationship is symmetrical about 0 ° as shown in FIG.

Next, in step 106 (S106), the in-plane rotation angle Φ _A of the sample that minimizes the X-ray transmittance T is selected. Based on the relationship between the sample in-plane rotation angle Φ and the X-ray transmittance T shown in FIG. 3, the sample in-plane rotation angles Φ that minimize the X-ray transmittance T are about −26 ° and about 26 °. Since it is symmetric with respect to 0 °, the minimum in-plane rotation angle Φ _{A is set} to 26 °.

Next, in step 108 (S108), measurement is performed to obtain the relationship between the sample inclination angle ψ and the X-ray transmittance T when the in- _{plane rotation angle Φ A of the sample is 26 °.} Specifically, the sample tilt angle ψ is changed by the sample tilt angle ψ adjustment stage 37 while the sample in-plane rotation angle is set to Φ _{A, that is, 26 ° by the sample in-plane rotation angle Φ stage 36.} The X-ray transmittance T is measured. The relationship between the sample inclination angle ψ obtained in this way and the X-ray transmittance T is shown in FIG. The sample inclination angle ψ changed by the sample inclination angle ψ adjustment stage 37 may be changed depending on the sample 100A to be analyzed, may be 0 ° or more and 45 ° or less, or may be 0 ° or more and 30 ° or less. It may be 0 ° or more and 10 ° or less. FIG. 4 shows a case where the sample inclination angle ψ changed by the sample inclination angle ψ adjustment stage 37 is 0 ° or more and 10 ° or less.

Then, At step 110 (S110), selects a specimen rotation angle [psi _A as the X-ray transmittance _{T S} that has been predetermined. In the present embodiment, X-rays transmittance T _S is assumed to be 10%. Specifically, in the relationship between the specimen rotation angle ψ and the X-ray transmittance T, the specimen rotation angle X-ray transmittance T _S becomes 10% is about 4 °. Therefore, the sample inclination angle ψ _{A is set} to 4 °. Incidentally, in the relationship between the specimen rotation angle ψ and the X-ray transmittance T, X-ray transmittance T _S or more, i.e., be of 10% or more, the specimen rotation angle ψ closest to the X-ray transmittance T _S The sample inclination angle ψ _A may be set. The X-ray transmittance T _S, upon deriving a sample tomographic image from the sample projected image is a value serving as a reference for usability determination, for example, a value in the range of from 5% to 20%.

Next, in step 112 (S112), at the sample inclination angle ψ _A selected, the sample in-plane rotation angle Φ is rotated by the sample in-plane rotation angle Φ stage 36, and the sample in-plane rotation angle Φ is rotated by the X-ray detector 20. Obtain multiple sample projection images with a sample in-plane rotation angle of Φ. Specifically, the sample in-plane rotation angle Φ stage 36 rotates the sample in-plane rotation angle Φ in the range of 0 ° ≦ Φ <360 ° to obtain 3600 sample projection images every 0.1 °. ..

Next, in step 114 (S114), a desired sample tomographic image is obtained by analyzing the sample projection image obtained in step 112 by the FBP method or the like in consideration of the inclination.

Through the above steps, the X-ray analysis method according to the present embodiment can be performed.

Next, it will be described that a good sample tomographic image can be obtained in a short time by the X-ray analysis method in the present embodiment. FIG. 5 shows the relationship between the in-plane rotation angle Φ of the sample and the X-ray transmittance T. In addition to the case where the sample inclination angle ψ = 0 ° in FIG. 3, the sample inclination angle ψ = 3 °, 4 ° The result of the case of is added. Further, FIG. 6 shows the relationship between the sample inclination angle ψ and the X-ray transmittance T. In addition to the case where the sample in-plane rotation angle Φ = 26 ° in FIG. 4, the sample in-plane rotation angle Φ = 0. The results obtained by adding the results for °, 10 °, 20 °, 30 °, 40 °, 50 °, 60 °, 70 °, 80 °, and 90 ° are shown.

By the way, it is known that data loss occurs in X-ray analysis by an X-ray laminography method or the like. The data loss rate is related to the X-ray transmittance T when the in-plane rotation angle Φ of the sample is changed at the sample inclination angle ψ, and when the sample inclination angle ψ is changed at the in-plane rotation angle Φ of the sample. A more accurate data loss rate can be derived when the relationship with the X-ray transmittance T is as large as possible. However, when measuring such a relationship, the analysis time increases as the measurement data increases.

In the present embodiment, as shown in FIGS. 3 and 4, the dependence of the sample in-plane rotation angle Φ at one sample inclination angle ψ is measured, and the dependence of the sample inclination angle ψ at one sample in-plane rotation angle Φ. I am measuring sex. This is because the data loss rate L can be derived with a slight error that does not affect the selection of the sample inclination angle ψ _A.

For example, in FIG. 5, when the dependence data of the angle of rotation Φ in the sample plane at the sample inclination angle ψ = 4 ° is required, first, based on FIG. 4, the X-ray transmittance T at the sample inclination angle ψ = 4 °. Confirm that is about 11%. Next, based on FIG. 3, the intersections (Φ, T) = (about 44 °, 11%) and (about −44 °, 11%) of the Φ-dependent data at T = 11% and the sample inclination angle ψ = 0 °. To get. In the region of −44 ° ≦ Φ ≦ 44 °, T = 11%, and in the region of Φ> 44 ° or Φ <−44 °, by using the Φ-dependent data at ψ = 0 °, the desired value at ψ = 4 ° Dependent data of the angle of rotation Φ in the sample plane can be obtained. The validity can be confirmed by looking at the actual results shown in FIG.

Similarly, in FIG. 6, when the dependent data of the sample inclination angle ψ at the sample in-plane rotation angle Φ = 60 ° is required, first, based on FIG. 3, X-rays at the sample in-plane rotation angle Φ = 60 ° are required. Confirm that the transmittance T is about 18%. Next, based on FIG. 4, the intersection (ψ, T) = (about 5 °, 18%) of the ψ-dependent data at T = 18% and the in-plane rotation angle Φ = 26 ° of the sample is obtained. In the region of ψ ≦ 5 °, T = 18%, and in the region of ψ> 5 °, the desired in-plane rotation angle Φ = 60 by using the ψ-dependent data at the sample in-plane rotation angle Φ = 26 °. Dependent data of the sample tilt angle ψ at ° can be obtained. The validity can be confirmed by looking at the actual results shown in FIG. By the method described above, it is possible to clearly distinguish the measurement conditions in which the X-ray transmittance T is less than 10% and 10% or more.

Next, the derivation of the data loss rate L will be described in more detail. FIG. 7 shows the polar coordinate display Radon space (x, Φ) in the case where there is no data loss (complete data) measured by the X-ray CT method, and this region is represented by ^{π x 2 z.} That is, when the entire region is filled with the sample projection image, the data loss rate L becomes 0.

FIG. 8 shows a data-deficient region in which the data of the sample projection image cannot be used in _{the angle range Φ W} of a certain in-plane rotation angle due to the absorption of X-rays by the sample. It is represented by π x ² _{zΦ W / 180 °.} In the range of −90 ° ≦ Φ ≦ 90 ° shown in FIG. 3, the data missing region is −40 ° ≦ Φ ≦ 40 ° at which the X-ray transmittance T is less than 10%. Therefore, the angle range Φ _W = 80 ° of the in-plane rotation angle of the sample is the data loss region. Therefore, data loss rate _{L 0} in the specimen rotation angle [psi = 0 ° is a 44.4% than 80 ° / 180 °.

FIG. 9 shows a data loss region in the case of the sample inclination angle ψ, and this region is represented by π z ³ tan ² ψ / 12. In the X-ray laminography method, since the projection surface is inclined, the sample projection image cannot fill all of the polar coordinate display Radon space. That is, as the sample inclination angle ψ increases, the data loss region increases regardless of the shape of the sample. The data loss rate L _ψ is represented by ^{z 2} tan ² ψ / 12x ^2. As the values of x and z, the size of the X-ray detector 20 (horizontal size: 10 mm, vertical size: 10 mm) can be used. By substituting x = horizontal size / 2 = 5 mm and z = vertical size = 10 mm, _{the value of the data loss rate L ψ at} the sample inclination angle ψ = 4 ° becomes 0.2%.

Regarding the values of x and z, when the size of the sample to be analyzed is sufficiently smaller than the size of the X-ray detector 20, the actual image used when deriving the sample tomographic image from the sample projection image. You may use the size. In such a sample, when ψ = 0 °, only the effect of X-ray sample absorption shown in FIG. 8 needs to be considered, and when ψ ≧ 4 °, the sample shown in FIG. 9 needs to be considered. Only the effect of tilt needs to be considered. However, in the region of 0 ° <ψ <4 °, it is necessary to consider the influences of both, and in particular, it is necessary to pay attention to the region where the influences of both overlap. When ψ <4 °, the region that overlaps with the X-ray sample absorption among the data missing regions due to the sample inclination ^{can be derived by π z 3} tan ² ψ / 12 × (Φ / 180 °). The result derived as described above is shown in FIG.

As shown in FIG. 10, the data loss rate L is the lowest when the sample inclination angle ψ is 4 °, and a good sample tomographic image is obtained by performing the measurement when the sample inclination angle ψ is 4 °. Can be obtained in a short time. According to the X-ray analysis method in the present embodiment, as described above, the time can be shortened to about 1/3 to 1/5 when the measurement of the 3rd level to the 5th level is performed.

The X-ray analyzer shown in FIG. 1 includes a translation X-axis adjustment stage 32, a translation Y-axis adjustment stage 33, an inclination Rx-axis adjustment stage 34, an inclination Ry-axis adjustment stage 35, and a sample in-plane rotation angle Φ stage 36. It has a sample inclination angle ψ adjustment stage 37 and the like. However, the X-ray analysis method in the present embodiment can also be performed using an X-ray analyzer that does not have the sample tilt angle ψ adjustment stage 37 for adjusting the sample tilt angle ψ.

Generally, in an X-ray analyzer having a tilt Rx axis, a tilt Ry axis, and a rotation axis having a rotation angle Φ in the sample plane, a desired sample tilt angle ψ can be obtained by combining the tilt Rx axis and the tilt Ry axis. It is possible to adjust as such. For example, assuming that the inclination Rx and the sample inclination angle ψ move in the same direction at Φ = 0 °, when ψ = 5 °, Rx = 5 ° and Ry = 0 ° may be set. When ψ = 5 ° in Φ = 90 °, Rx = 0 ° and Ry = 5 ° may be set. Similarly, when ψ = 5 ° in Φ = 45 °, Rx = 3.45 ° and Ry = 3.45 ° may be set. Generalizing these, Rx = arctan (cosΦtanψ) and Ry = arctan (sinΦtanψ).

Therefore, even in an X-ray analyzer that does not have the sample inclination angle ψ adjustment stage 37, it becomes desirable by adjusting the inclination Rx and the inclination Ry by the inclination Rx axis adjustment stage 34 and the inclination Ry axis adjustment stage 35. It is possible to adjust the sample inclination angle ψ. In this case, the operation for adjusting the sample inclination angle ψ becomes complicated, and the adjustment takes time.

Further, although the case where the X-ray source 10 is a monochromatic X-ray of 30 keV has been described, lower energy X-rays or higher energy X-rays may be used depending on the shape of the sample to be analyzed, and further. , White X-rays may be used. Moreover, although the case where the X-ray emitted from the X-ray source 10 is a parallel X-ray has been described, it may be a divergent X-ray. In the case of divergent X-rays, if the Φ rotation is 180 °, the entire polar coordinate display Radon space cannot be satisfied even with the X-ray CT method, and a data loss area occurs. , It is possible to prevent the occurrence of a data loss area.

Further, in the X-ray analyzer according to the present embodiment, in addition to one two-dimensional detector which is the X-ray detector 20, another 0-dimensional detector (scintillation detector, PIN photodiode detector, ion chamber) ( Ionization chamber) etc.) may be used. By performing step 104 and step 108 using such another 0-dimensional detector, the X-ray analysis method in the present embodiment can be performed in a shorter time.

In the present embodiment, the case of the sample in-plane rotation angle Φ _A and the sample inclination angle ψ _{A in} the case of the sample 100A has been described, but when generalized, the sample in-plane rotation angle Φ _N and the sample inclination angle ψ You may think of it as _N.

[Second Embodiment]
Next, the X-ray analysis method in the second embodiment will be described. In the X-ray analysis method of the present embodiment, it is determined whether the sample is suitable for analysis by the X-ray CT method or the analysis by the X-ray laminography method, and the analysis is performed by the method suitable for the analysis. Therefore, a good sample tomographic image can be obtained. The analysis by the X-ray laminography method is the same as that of the first embodiment.

The X-ray analysis method in the present embodiment will be described with reference to the flowchart shown in FIG.

First, in step 202 (S202), the position of the sample to be analyzed installed on the sample table 31 is adjusted. Specifically, the translation of the sample to be analyzed installed on the sample table 31 by the translation X-axis adjustment stage 32, the translation Y-axis adjustment stage 33, the inclination Rx-axis adjustment stage 34, and the inclination Ry-axis adjustment stage 35. The X-axis, translational Y-axis, tilt Rx-axis, and tilt Ry-axis are adjusted. In this adjustment, the translational X-axis, translational Y-axis, tilt Rx-axis, and tilt Ry-axis of the sample are adjusted so that the center line of the sample to be analyzed coincides with the rotation axis of the in-plane rotation angle Φ of the sample. ..

Next, in step 204 (S204), measurement is performed to obtain the relationship between the in-plane rotation angle Φ of the sample and the X-ray transmittance T. Specifically, the X-ray transmittance T of the sample is measured by rotating the sample in-plane rotation angle Φ stage 36 in the range of −90 ° ≦ Φ <90 °. The X-ray transmission T can be measured by using the X-ray detector 20, and an X-ray detector for measuring the X-ray transmission T is provided separately from the X-ray detector 20. The measurement may be performed by an X-ray detector.

Next, in step 206 (S206), the in-plane rotation angle Φ _N of the sample that minimizes the X-ray transmittance T is selected.

Next, in step 208 (S208), measurement is performed to obtain the relationship between the sample inclination angle ψ and the X-ray transmittance T in the case of _{the sample in-plane rotation angle Φ N.} Specifically, the X-ray transmittance T is changed by changing the sample tilt angle ψ by the sample tilt angle ψ adjustment stage 37 in a state where the sample in-plane rotation angle Φ stage 36 sets the sample in-plane rotation angle to Φ _N. To measure.

Then, At step 210 (S210), selects a specimen rotation angle [psi _N as the X-ray transmittance _{T S} that has been predetermined.

Next, in step 212 (S212), based on the results obtained in steps 204 and 208, the data loss rate L _{0 at} the sample tilt angle ψ = 0 ° and the data loss rate at the sample tilt angle ψ = ψ _N L _N is derived. Derivation of these data loss rates is carried out in either the polar coordinate display radon space in which the sample projection image is displayed in polar coordinates or the frequency space that can be obtained by the Fourier transform of this radon space.

Next, in step 214 (S214), it is determined whether or not _{L N} <L _0. When L _N <L _0, the process proceeds to step 216, and when L _N ≥ L ₀ , the process proceeds to step 220.

In step 216 (S216), at the selected sample inclination angle ψ _N , the sample in-plane rotation angle Φ is rotated by the stage 36, and the sample in-plane rotation angle Φ is rotated by the X-ray detector 20 in the predetermined sample in-plane. Obtain multiple sample projection images with a rotation angle of Φ. Specifically, the sample in-plane rotation angle Φ stage 36 rotates the sample in-plane rotation angle Φ in the range of 0 ° ≦ Φ <360 ° to obtain 3600 sample projection images every 0.1 °. ..

Next, in step 218 (S218), a desired sample tomographic image is obtained by analyzing the sample projection image obtained in step 216 by the FBP method or the like in consideration of the inclination.

In step 220 (S220), at the sample inclination angle ψ = 0 °, the sample in-plane rotation angle Φ is rotated by the stage 36, and the sample in-plane rotation is rotated by the X-ray detector 20. Obtain multiple sample projection images with an angle of Φ. Specifically, the in-plane rotation angle Φ stage 36 rotates the in-plane rotation angle Φ in the range of 0 ° ≤ Φ <180 ° to obtain 1800 sample projection images every 0.1 °. .. In the X-ray CT method, the angle of rotation Φ in the sample plane is the same in the range of 0 ° to 180 ° and the range of 180 ° to 360 °. Measurement may be performed at a sample in-plane rotation angle Φ in the half range of the case of the minography method.

Next, in step 222 (S222), a desired sample tomographic image is obtained by analyzing the sample projection image obtained in step 216 by the FBP method or the like.

From the above, the X-ray analysis method in the present embodiment can be performed. The in-plane rotation angle Φ _{N of} the sample and the inclination angle ψ _N of the sample are generalized sample values.

Next, the case where the samples are the sample 100A, the sample 100B, and the sample 100C will be specifically described.

(Sample 100A)
Next, a case where the sample 100A is analyzed by the X-ray analysis method in the present embodiment will be described. Specifically, the X-rays generated by the X-ray source 10 are monochromatic and parallel X-rays of 30 keV, and the sample 100A to be analyzed is Si having a size of 5 mm × 10 mm and a thickness of 0.5 mm. It is a chip.

A case where the sample 100A is analyzed based on the flowchart shown in FIG. 11 will be described.

First, after performing step 202, as shown in FIG. 3, the relationship between the in-plane rotation angle Φ of the sample and the X-ray transmittance T is obtained by step 204, and in step 206, the sample is obtained based on FIG. _{The angle of rotation Φ A} in the sample plane that minimizes the X-ray transmittance T of 100 A is selected to be 26 °.

Next, step 208 is performed, and as shown in FIG. 4, the relationship between the sample inclination angle ψ and the X-ray transmittance T when the in- _{plane rotation angle Φ A of the sample is 26 ° is obtained, and in step 210,} selecting a specimen rotation angle [psi _a as a predetermined keep the X-ray transmittance T _S based on FIG. 4 to 4 °.

Next, in step 212, based on the result obtained in step 204 and step 208, the data loss ratio _{L 0} in the specimen rotation angle [psi = 0 °, and, the data loss rate _{L A} in the sample tilt angle [psi = [psi _A Derived. FIG. 10 shows the relationship between the sample inclination angle ψ derived from FIGS. 3 and 4 and the data loss rate L. If according to FIG. 10, a data loss rate _L 0 = 44.4% in the specimen rotation angle [psi = 0 °, a data loss rate _L A = 0.2% in the specimen rotation angle ψ = ψ _A.

Next, in step _214, L A <is a determination of whether an _{L 0,} L A _<L since it is _0, a given sample plane rotation angle in the specimen rotation angle [psi _A at step 216 [Phi Obtain multiple sample projection images of. After that, a desired sample tomographic image of sample 100A is obtained by analysis by the FBP method or the like in consideration of the inclination in step 218.

(Sample 100B)
Next, a case where the sample 100B is analyzed by the X-ray analysis method in the present embodiment will be described. Specifically, the X-rays generated by the X-ray source 10 are monochromatic and parallel X-rays of 30 keV, and the sample 100B to be analyzed is a Si chip having a size of 6 mm × 6 mm and a thickness of 2 mm. be.

A case where the sample 100B is analyzed based on the flowchart shown in FIG. 11 will be described.

First, after performing step 202, as shown in FIG. 12, the relationship between the in-plane rotation angle Φ of the sample and the X-ray transmittance T is obtained by step 204, and in step 206, the sample is obtained based on FIG. X-ray transmittance T 100B is selected smallest sample plane rotation angle [Phi _B to 45 °.

Next, step 208 is performed, and as shown in FIG. 13, the relationship between the sample inclination angle ψ and the X-ray transmittance T when the in- _{plane rotation angle Φ B of the sample is 45 ° is obtained, and in step 210,} the specimen rotation angle [psi _B as the X-ray transmittance T _S which has been predetermined on the basis of FIG. 13 selects the 16 °.

Next, in step 212, based on the result obtained in step 204 and step 208, the data loss ratio _{L 0} in the specimen rotation angle [psi = 0 °, and, the data loss rate _{L B} in the specimen rotation angle [psi = [psi _B Derived. FIG. 14 shows the relationship between the sample inclination angle ψ derived from FIGS. 12 and 13 and the data loss rate L. If according to FIG. 14, a data loss rate _L 0 = 11.1% in the specimen rotation angle [psi = 0 °, which is a data loss ratio _L B = 2.7% in the specimen rotation angle ψ = ψ _B.

Next, in step _214, although the determination of whether an _{L B <L 0, L B} < because it is _{L 0,} a given sample plane rotation angle in the specimen rotation angle [psi _B at step 216 [Phi Obtain multiple sample projections of. After that, a desired sample tomographic image of sample 100B is obtained by analysis by the FBP method or the like in consideration of the inclination in step 218.

(Sample 100C)
Next, a case where the sample 100C is analyzed by the X-ray analysis method in the present embodiment will be described. Specifically, the X-rays generated by the X-ray source 10 are monochromatic and parallel X-rays of 30 keV, and the sample 100C to be analyzed has a size of 5.5 mm × 5.5 mm and a thickness of 4 mm. Si chip.

A case where the sample 100C is analyzed based on the flowchart shown in FIG. 11 will be described.

First, after performing step 202, as shown in FIG. 15, the relationship between the in-plane rotation angle Φ of the sample and the X-ray transmittance T is obtained by step 204, and in step 206, the sample is obtained based on FIG. X-ray transmittance T of 100C is selected smallest sample plane rotation angle [Phi _C to 45 °.

Next, the step 208, as shown in FIG. 16, the sample plane rotation angle [Phi _C is obtained the relationship between the specimen rotation angle ψ and the X-ray transmittance T in the case of 45 °, in step 210, the specimen rotation angle [psi _C as a predetermined keep the X-ray transmittance T _S based on FIG. 13 selects the 32 °.

Next, in step 212, based on the results obtained in steps 204 and 208, the data loss rate L ₀ at the sample tilt angle ψ = 0 ° and the data loss rate L _C at the sample tilt angle ψ = ψ _{C are obtained.} Derived. FIG. 17 shows the relationship between the sample inclination angle ψ derived from FIGS. 15 and 16 and the data loss rate L. If according to FIG. 17, a data loss rate _L 0 = 2.2% in the specimen rotation angle [psi = 0 °, which is a data loss ratio _L C = 13.0% in the specimen rotation angle ψ = ψ _C.

Next, in step _214, although the determination of whether a _{L C <L 0, L C} < since it is not a _{L 0,} a given sample plane rotation in the specimen rotation angle [psi = 0 ° in step 220 Obtain multiple sample projection images with an angle of Φ. After that, a desired sample tomographic image of sample 100C is obtained by analysis by the FBP method or the like in step 222.

The contents other than the above are the same as those in the first embodiment.

Although the embodiments have been described in detail above, the embodiments are not limited to the specific embodiments, and various modifications and changes can be made within the scope of the claims.

Regarding the above explanation, the following additional notes will be further disclosed.
(Appendix 1)
In an X-ray analysis method in which a sample is placed in a sample setting portion, the sample is irradiated with X-rays from an X-ray source, and a two-dimensional image of X-rays transmitted through the sample is detected by an X-ray detector.
A step of obtaining a relationship between the in-plane rotation angle of the sample Φ and the X-ray transmittance transmitted through the sample by measuring the transmittance of X-rays transmitted through the sample while rotating the sample.
Based on the relationship between the obtained sample in-plane angle of rotation Φ and the X-ray transmittance, a step of obtaining a _{sample in-plane angle of rotation Φ N that minimizes the X-ray transmittance, and}
The relationship between the sample tilt angle ψ and the X-ray transmittance transmitted through the sample by measuring the transmittance of the X-ray transmitted through the sample while tilting the sample in the state of the in-plane rotation angle Φ _{N of the sample.} And the process of obtaining
Obtained based on the relationship between the specimen rotation angle [psi and X-ray transmittance, the step of selecting a specimen rotation angle [psi _N such that a predetermined X-ray transmittance T _S,
A step of acquiring a two-dimensional sample projection image of the sample by detecting X-rays transmitted through the sample while rotating the sample in a state where the sample is tilted at the sample inclination angle ψ _N.
A process of obtaining a tomographic image of the sample based on the acquired projected image of the sample, and
An X-ray analysis method characterized by having.
(Appendix 2)
After the step of selecting the sample inclination angle ψ _N,
Wherein the data loss ratio in the specimen rotation angle [psi _N L _{N and,} a step of the specimen rotation angle is derived the data loss rate L ₀ in the case of 0 °,
It has a step of comparing the data loss rate L _N and the data loss rate L _{0, and when L N} <L ₀ , the sample is tilted at the sample inclination angle ψ _{N, and the sample is 2} The X-ray analysis method according to Appendix 1, wherein a step of obtaining a three-dimensional sample projection image and a step of obtaining a tomographic image of the sample are performed.
(Appendix 3)
In the step of comparing the data loss rate L _N and the data loss rate L ₀ , when L _N ≧ L ₀ , a two-dimensional sample projection image of the sample with the sample inclination angle of 0 °. And the process of getting
A process of obtaining a tomographic image of the sample based on the acquired projected image of the sample, and
The X-ray analysis method according to Appendix 2, wherein the X-ray analysis method is characterized by having.
(Appendix 4)
An X-ray source that emits X-rays that irradiate the sample,
The sample installation section where the sample is installed and
An X-ray detector that detects a two-dimensional image of X-rays that have passed through the sample,
Control unit and
Have,
The control unit measures the transmittance of X-rays transmitted through the sample while rotating the sample to obtain a relationship between the in-plane rotation angle Φ of the sample and the X-ray transmittance transmitted through the sample.
Based on the relationship between the obtained in-plane rotation angle Φ of the sample and the X-ray transmittance, an in-plane rotation angle Φ _N of the sample having the minimum X-ray transmittance was obtained.
The relationship between the sample tilt angle ψ and the X-ray transmittance transmitted through the sample by measuring the transmittance of the X-ray transmitted through the sample while tilting the sample in the state of the in-plane rotation angle Φ _{N of the sample.} Get,
Obtained based on said relationship between the specimen rotation angle [psi and the X-ray transmittance, selects a specimen rotation angle [psi _N such that a predetermined X-ray transmittance T _S,
A two-dimensional sample projection image of the sample is obtained by detecting X-rays transmitted through the sample while rotating the sample in a state where the sample is tilted at the sample inclination angle ψ _N.
An X-ray analyzer characterized in that control is performed to obtain a tomographic image of the sample based on the acquired projected image of the sample.
(Appendix 5)
The control unit
Wherein the data loss ratio in the specimen rotation angle [psi _N L _N, and the specimen rotation angle is derived the data loss rate L ₀ in the case of 0 °,
Comparing the data loss rate L _N and the data loss rate L ₀ , when L _N <L ₀ , the two-dimensional sample of the sample is in a state where the sample is tilted at the sample inclination angle ψ _N. The X-ray analyzer according to Appendix 4, wherein a projected image is acquired and control is performed to obtain a tomographic image of the sample.
(Appendix 6)
The control unit
When L _N ≥ L ₀ , a two-dimensional sample projection image of the sample is acquired with the sample inclination angle of 0 °.
The X-ray analyzer according to Appendix 5, wherein a tomographic image of the sample is obtained based on the acquired projected image of the sample.

10 X-ray source 20 X-ray detector 30 Sample setting 31 Sample stand 32 Translation X-axis adjustment stage 33 Translation Y-axis adjustment stage 34 Tilt Rx-axis adjustment stage 35 Tilt Ry-axis adjustment stage 36 Sample in-plane rotation angle Φ stage 37 Sample Tilt angle ψ adjustment stage 50 Control unit 51 Analysis unit 100 Sample

Claims (6)

A two-dimensional sample projection image of the sample is obtained by placing the sample in the sample setting section, irradiating the sample with X-rays from an X-ray source , and detecting the X-rays transmitted through the sample with an X-ray detector. Then, in the X-ray analysis method for acquiring the tomographic image of the sample,
By measuring the transmittance of X-rays transmitted through the sample while rotating the sample around the axis of in-plane rotation of the sample, the in-plane rotation angle Φ of the sample and the X-ray transmittance transmitted through the sample are obtained. And the process of obtaining the relationship
Based on the relationship between the obtained sample in-plane angle of rotation Φ and the X-ray transmittance, a step of obtaining a _{sample in-plane angle of rotation Φ N that minimizes the X-ray transmittance, and}
The sample tilt angle ψ by measuring the transmittance of X-rays transmitted through the sample while tilting the sample with respect to the plane orthogonal to the axis of the in-plane rotation in the state of the sample in-plane rotation angle Φ _N. And the step of obtaining the relationship between the X-ray transmittance transmitted through the sample and
Obtained based on the relationship between the specimen rotation angle [psi and X-ray transmittance, the step of selecting a specimen rotation angle [psi _N such that a predetermined X-ray transmittance T _S,
By detecting X-rays transmitted through the sample while rotating the sample around the axis of in-plane rotation in a state where the sample is tilted at the sample inclination angle ψ _{N, the sample is two-dimensional.} The process of acquiring a sample projection image and
A process of acquiring a tomographic image of the sample based on the acquired projected image of the sample, and
An X-ray analysis method characterized by having. After the step of selecting the sample inclination angle ψ _N,
Wherein the data loss ratio in the specimen rotation angle [psi _N L _{N and,} a step of the specimen rotation angle is derived the data loss rate L ₀ in the case of 0 °,
It has a step of comparing the data loss rate L _N and the data loss rate L _{0, and when L N} <L ₀ , the sample is tilted at the sample inclination angle ψ _{N, and the sample is 2} The X-ray analysis method according to claim 1, wherein a step of obtaining a three-dimensional sample projection image and a step of obtaining a tomographic image of the sample are performed. In the step of comparing the data loss rate L _N and the data loss rate L ₀ , when L _N ≧ L ₀ , a two-dimensional sample projection image of the sample with the sample inclination angle of 0 °. And the process of getting
A process of obtaining a tomographic image of the sample based on the acquired projected image of the sample, and
The X-ray analysis method according to claim 2, wherein the X-ray analysis method is characterized by having. An X-ray source that emits X-rays that irradiate the sample,
The sample installation section where the sample is installed and
An X-ray detector that detects a two-dimensional image of X-rays that have passed through the sample,
Control unit and
Have,
The control unit
A sample is measured by measuring the transmittance of X-rays emitted from the X-ray source and transmitted through the sample while rotating the sample installed in the sample setting portion around the axis of in-plane rotation of the sample. Obtaining the relationship between the in-plane rotation angle Φ and the X-ray transmittance that has passed through the sample,
Based on the relationship between the obtained in-plane rotation angle Φ of the sample and the X-ray transmittance, an in-plane rotation angle Φ _N of the sample having the minimum X-ray transmittance was obtained.
With the sample in-plane rotation angle Φ _N , the sample placed in the sample setting portion is tilted with respect to a plane orthogonal to the in-plane rotation axis, and is emitted from the X-ray source and transmitted through the sample. By measuring the transmittance of the X-rays, the relationship between the sample inclination angle ψ and the transmittance of the X-rays transmitted through the sample was obtained.
Obtained based on said relationship between the specimen rotation angle [psi and the X-ray transmittance, selects a specimen rotation angle [psi _N such that a predetermined X-ray transmittance T _S,
In a state where the sample installed in the sample setting portion is tilted at the sample inclination angle ψ _N , the sample is emitted from the X-ray source and transmitted through the sample while rotating around the axis of the in-plane rotation. By detecting the X-rays generated by the X-ray detector, a two-dimensional sample projection image of the sample is obtained.
An X-ray analyzer characterized in that control is performed to obtain a tomographic image of the sample based on the acquired projected image of the sample. The control unit
Wherein the data loss ratio in the specimen rotation angle [psi _N L _N, and the specimen rotation angle is derived the data loss rate L ₀ in the case of 0 °,
Comparing the data loss rate L _N and the data loss rate L ₀ , when L _N <L ₀ , the two-dimensional sample of the sample is in a state where the sample is tilted at the sample inclination angle ψ _N. The X-ray analyzer according to claim 4, wherein a projected image is acquired and control is performed to obtain a tomographic image of the sample. The control unit
When L _N ≥ L ₀ , a two-dimensional sample projection image of the sample is acquired with the sample inclination angle of 0 °.
The X-ray analyzer according to claim 5, wherein a tomographic image of the sample is obtained based on the acquired projected image of the sample.

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