JP2013148431A - Total reflection x-ray analysis method and total reflection x-ray analysis device - Google Patents

Total reflection x-ray analysis method and total reflection x-ray analysis device Download PDF

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JP2013148431A
JP2013148431A JP2012008497A JP2012008497A JP2013148431A JP 2013148431 A JP2013148431 A JP 2013148431A JP 2012008497 A JP2012008497 A JP 2012008497A JP 2012008497 A JP2012008497 A JP 2012008497A JP 2013148431 A JP2013148431 A JP 2013148431A
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Naoki Awaji
直樹 淡路
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Fujitsu Ltd
富士通株式会社
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Abstract

A depth distribution of XAFS is quickly measured.
[Solution]
A step of forming a divergent X-ray beam 3 consisting of X-rays of a single wavelength emanating from a linear or point-like focal point 4, and a divergent X-ray beam 3 so that a part of the X-rays are incident at a total reflection critical angle Irradiating the surface of the sample 1 with each other, calculating the viewing angle of the X-rays incident on each of a plurality of regions defined on the surface of the sample 1, and the intensity of the secondary radiation 5 emitted from each region. A fourth step of measuring using the position sensitive detector 31, a fifth step of calculating an intrusion X-ray intensity distribution for each region based on the viewing angle, and changing the X-ray wavelength to another wavelength, A sixth step of repeating the fourth to fifth steps, a step of calculating a depth distribution of XAFS based on the secondary radiation 5 intensity measured in the sixth step and the calculated X-ray intensity distribution; Have
[Selection] Figure 1

Description

  The present invention relates to a total reflection X-ray analysis method and a total reflection X-ray analysis apparatus.
  In devices used in electronic equipment, such as semiconductor devices or magnetic heads, it is known that the structure of a very shallow region near the surface has a great influence on device characteristics. For example, the impurity distribution and chemical bonding state of the shallow impurity layer formed in the semiconductor layer, or the oxidation state of the semiconductor layer surface greatly affects the characteristics of the semiconductor device. In addition, the interface structure between the ferromagnetic thin film and the tunnel barrier film greatly affects the characteristics of the magnetic head using the tunneling magnetoresistance (TMR) effect.
  The XAFS method for observing an X-ray absorption fine structure (XAFS) can detect the atomic concentration and chemical bond state in a sample based on the absorption fine structure near the X-ray absorption edge. In particular, the total reflection XAFS method using the total reflection X-ray analysis method in which X-rays are incident on the sample surface at a viewing angle near the total reflection critical angle can change the penetration depth of the X-rays according to the viewing angle. Therefore, it is possible to know the atomic distribution in the depth direction near the sample surface and the change in the chemical bonding state in the depth direction. For this reason, the total reflection X-ray analysis method is widely used for XAFS observation as an excellent device analysis method.
  In a conventional total reflection X-ray analysis method, white X-rays emitted from a light source are dispersed to form a parallel X-ray beam composed of monochromatic X-rays having a wavelength λ, and this parallel X-ray beam is applied to the sample surface at the critical point of total reflection. Incident with a viewing angle near the corner. Then, the intensity of fluorescent X-rays emitted from the sample surface, photoelectrons, or reflected X-rays reflected from the sample surface is measured, and the X-ray absorption amount of the X-ray having the wavelength λ is calculated.
  Next, the sample is tilted to change the viewing angle, and the above-described measurement of the intensity of fluorescent X-rays and the calculation of the X-ray absorption amount are performed. When the viewing angle changes, the penetration depth of X-rays changes. For example, when the penetration depth is deep, X-ray absorption due to absorption of atoms at a deeper position is added. For this reason, it is possible to know the change in the X-ray absorption amount corresponding to the change in the depth direction distribution of the atoms to be measured or the chemical bond in the depth direction.
  Furthermore, the wavelength λ of the parallel X-ray beam is changed, and X-ray absorption amounts at a plurality of viewing angles at a plurality of wavelengths are calculated. As a result, the wavelength λ dependency of the X-ray absorption amount, that is, XAFS data is acquired. And the change of the depth direction of XAFS can be detected from the viewing angle dependency.
  As described above, in the conventional total reflection X-ray analysis method, a parallel X-ray beam having a wavelength λ is irradiated on a sample, the intensity of fluorescent X-rays or the like when the viewing angle and the wavelength λ are changed, and the XAFS Changes in the depth direction are detected.
Japanese Patent Laid-Open No. 04-106463 JP 2002-116159 A JP 2001-124711 A
  As described above, in the conventional total reflection X-ray analysis method, a sample is irradiated with a parallel X-ray beam of monochromatic X-rays, and fluorescent X-rays, photoelectrons or reflected X-rays (hereinafter referred to as “secondary radiation”) emitted from the sample. And the X-ray absorption amount is calculated therefrom. Then, the intensity of the secondary radiation is measured while changing the viewing angle and the wavelength of the parallel X-ray beam, and the X-ray absorption amount is calculated as a function of the viewing angle and the wavelength. Based on the X-ray absorption amount calculated as a function of the viewing angle and the wavelength, a change in the depth direction of the XAFS is detected.
  In this method, in order to know the dependency of the X-ray absorption amount on the viewing angle and the wavelength, the intensity of the secondary radiation must be measured for a number of different viewing angles and a number of different wavelengths. The viewing angle must be precisely set with an error of a few seconds. The setting of the viewing angle is performed by mechanically tilting the sample. In order to keep the inclination of the sample within the allowable error, it takes time to set the inclination. The wavelength is changed by mechanically rotating and translating the single crystal constituting the monochromator. This rotation and translation must be performed precisely so that the traveling direction of the parallel X-ray beam does not change and a desired wavelength is selected, and setting takes time. For this reason, in order to perform measurement under conditions in which the viewing angle and the wavelength are changed, there is a problem that a long time is required for setting and the measurement time becomes long.
  The present invention provides a total reflection X-ray analysis method capable of detecting changes in the depth direction of XAFS in a short time by measuring the secondary radiation intensity at a plurality of viewing angles while keeping the inclination of the sample constant. Another object of the present invention is to provide a total reflection X-ray analyzer.
  According to one aspect of the present invention for solving the above problem, a divergent X-ray beam comprising a single wavelength selected from a plurality of wavelengths and consisting of X-rays diverging from a linear or point-like focal point. Irradiating the sample surface with the divergent X-ray beam so that a part of the X-rays constituting the divergent X-ray beam are incident on the sample surface at a critical angle of total reflection. Step 2, a third step of calculating, for each of the regions, a viewing angle of the X-ray incident on each of the plurality of regions defined on the sample surface, and emission from each of the regions A fourth step of measuring the intensity of the fluorescent X-rays, the intensity of the photoelectrons or the intensity of the reflected X-rays reflected from each of the regions using a position sensitive detector, and the sample from the calculated viewing angle The X-ray intensity distribution in the depth direction of the X-rays penetrating into A fifth step of calculating for each, and changing the wavelength of the X-ray to another single wavelength selected from the plurality of wavelengths, repeating the fourth to fifth steps, for each region A sixth step of measuring the intensity of the fluorescent X-rays, the photoelectrons or the reflected X-rays for the plurality of wavelengths, and calculating the X-ray intensity distribution for the plurality of wavelengths for each region; Based on the intensity of the fluorescent X-ray, the photoelectron or the reflected X-ray measured in the sixth step, and the X-ray intensity distribution calculated in the sixth step, an X-ray absorption fine structure (XAFS) And a step of calculating a depth direction distribution of the sample. The method of total reflection X-ray analysis is provided.
  According to the present invention, the secondary radiation intensity at a plurality of viewing angles is measured in a state where the inclination of the sample is kept constant. For this reason, since it is not necessary to change the inclination of the sample in order to change the viewing angle, a change in the depth direction of the XAFS can be detected in a short time.
1 is a configuration diagram of a total reflection X-ray analyzer according to a first embodiment of the present invention. The partial expanded sectional view of the total reflection X-ray analyzer of 1st Embodiment of this invention Functional configuration diagram of a computer according to the first embodiment of this invention Measurement process diagram of the first embodiment of the present invention (No. 1) Measurement process diagram of the first embodiment of the present invention (part 2) Measurement process diagram of the first embodiment of the present invention (part 3) A diagram showing the relationship between reflection intensity and viewing angle Diagram explaining the energy decomposition function of the detector The figure showing the viewing angle dependence of the penetration depth of 1st Embodiment of this invention The figure showing the intensity distribution of the intrusion X-ray calculated in the first embodiment Sectional view of the total reflection X-ray fluorescence spectrometer of the comparative example Sectional drawing of the total reflection X-ray analyzer of 2nd Embodiment of this invention The block diagram of the total reflection X-ray analyzer of 3rd Embodiment of this invention The block diagram of the divergent X-ray beam forming apparatus of 4th Embodiment of this invention The block diagram of the divergent X-ray beam forming apparatus of 5th Embodiment of this invention
  The first embodiment of the present invention relates to a total reflection X-ray analysis method for measuring the intensity of fluorescent X-rays emitted from a sample surface using a position sensitive detector.
  FIG. 1 is a configuration diagram of the total reflection X-ray analysis apparatus according to the first embodiment of the present invention, and shows the main configuration of the total reflection X-ray analysis apparatus used in the first embodiment.
  Referring to FIG. 1, a total reflection X-ray analysis apparatus 101 used in the first embodiment includes a divergent X-ray beam former 10, a position sensitive detector 31, a position sensitive detector 31, and a sample 1. A chamber 60 is provided. The divergent X-ray beam former 10 forms a divergent X-ray beam 3 composed of monochromatic X-rays using radiation (SOR light) as incident X-rays 2. The position sensitive detector 31 measures the intensity of the fluorescent X-ray 5 emitted from the surface of the sample 1 irradiated with the divergent X-ray beam 3.
  The divergent X-ray beam former 10 includes a monochromator 11 in which two crystals are arranged in parallel, and a reflecting mirror 12 having a linear or dotted focal point 4.
  The monochromator 11 includes a first crystal 11a and a second crystal 11b arranged in parallel. The first and second crystals 11a and 11b are placed on a turntable that rotates within the plane of FIG. 1 (rotation direction 11r), and the surface of the second crystal 11b is rotated on a rotation axis (perpendicular to the plane of FIG. 1). It can be rotated as a rotation axis. Further, the first crystal 11a and the second crystal 11b are provided with a moving mechanism for moving the first crystal 11a in the direction perpendicular to the surface of the second crystal 11b (moving direction 11s), while maintaining parallel with the second crystal 11b. The interval between and can be changed.
  In the first embodiment, radiated light is used as the incident X-ray beam 2. The emitted light has a continuous wavelength within the wavelength range required for XAFS analysis and can be considered as a substantially parallel X-ray beam. The incident X-ray beam 2 is incident on the first crystal 11a, and only the X-ray having a wavelength at which the angle between the traveling direction 2d of the incident X-ray beam 2 and the lattice plane of the first crystal 11a satisfies the Bragg condition is the first. And it reflects by the 2nd crystals 11a and 11b, and is output from the monochromator 11 as a monochromatic parallel X-ray beam 2-1. At this time, the wavelength of the parallel X-ray beam 2-1 output from the monochromator 11 can be changed by rotating the first and second crystals in the rotation direction 11r. Furthermore, by moving the first crystal in the movement direction 11s, the position and traveling direction of the parallel X-ray beam 2-1 after the wavelength change can be kept the same as before the wavelength change.
  The reflecting mirror 12 condenses the incident parallel X-ray beam 2-1 at the focal point 4. When, for example, a cylindrical mirror is used as the reflecting mirror 12, the parallel X-ray beam 2-1 is focused on a linear focal point 4 (a line perpendicular to the paper surface of FIG. 1). Further, the reflecting mirror 12 can be focused on the spot-like focal point 4 using a toroidal mirror or two cylindrical mirrors.
  The parallel X-ray beam 2-1 collected on the focal point 4 by the reflecting mirror 12 forms a divergent X-ray beam 3 composed of monochromatic X-rays that diverge around the focal point 4 after passing through the focal point 4. It is preferable to provide a slit 10a having an aperture at the position of the focal point 4 and a slit 10b for limiting the divergence angle of the divergent X beam, thereby shielding stray light and avoiding unnecessary noise.
  As an incident X-ray beam 2, radiation light having a rectangular cross section having a width of 5 mm (width in the xy plane) and a height of 0.2 mm (width in the y direction) is applied to a cylindrical reflector 12 having a curvature radius of 40 m at a viewing angle of 0. When incident at .15 degrees, a divergent X-ray beam 3 diverging with a divergence angle of 0.12 degrees was formed.
  As a sample 1, a silicon substrate having a diameter of 100 mm and having an As ion implantation layer formed on the upper surface thereof was used. The sample 1 is placed on the holding table 20 installed in the chamber 60.
  The holding table 20 includes a base 20b that can be translated in the xyz-axis direction and a goniometer 20a disposed on the base 20b. The goniometer 20a can rotate in a rotation direction 20r about a rotation axis perpendicular to the paper surface of FIG. 1 and a rotation direction orthogonal to the rotation direction 20r. The sample 1 is placed on the upper surface of the goniometer 20a, and is held in a predetermined posture, that is, a predetermined position and a predetermined inclination by the parallel movement of the base 20b and the rotation of the goniometer 20a.
  In this specification, for simplicity of explanation, the surface of the sample 1 is held parallel to the xy plane (a plane perpendicular to the paper surface of FIG. 1), and the divergent X-ray beam 3 and the reflected X-ray beam 7 are in the xz plane (see FIG. The description will be made on the assumption that the image travels in a plane parallel to the sheet of FIG.
  X-ray transmission windows 61 and 62 that transmit X-rays are provided on the left and right side walls of the chamber 60. The divergent X-ray beam 3 emitted from the divergent X-ray beam former 10 passes through the X-ray transmission window 61 and travels into the chamber 60 to irradiate the surface of the sample 1. At this time, as will be described later, the inclination of the sample 1 is set so that the viewing angle with respect to the surface of the sample 1 is in the vicinity of the total reflection critical angle.
  Various radiations such as fluorescent X-rays 5 and photoelectrons are emitted from the surface of the sample 1 irradiated with the divergent X-ray beam 3. Further, the divergent X-ray beam 3 irradiated on the surface of the sample 1 is reflected on the surface of the sample 1 to become reflected X-rays 7, passes through the X-ray transmission window 62, and is emitted outside the chamber 60.
  The chamber 60 is provided with a gas inlet 60a and a gas outlet 60b, and the inside of the chamber 60 is filled with He gas introduced from the gas inlet 60a. The He gas is discharged from the gas discharge port 60b. Thereby, attenuation of the divergent X-ray beam 3 and the fluorescent X-ray 5 is prevented. The chamber 60 may be evacuated. Further, in the first embodiment for measuring fluorescent X-rays, the inside of the chamber can be made the atmosphere. Further, it is preferable that the path from the incident X-ray 2 to the chamber 60 where the divergent X-ray beam 3 is formed and the path of the reflected X-ray 7 are made into a vacuum or He atmosphere to suppress X-ray attenuation and unnecessary scattering. .
  A position sensitive detector 31 is disposed in the chamber 60 so as to face the surface of the sample 1. The position-sensitive detector 31 includes a detector 31a in which X-ray detection elements are arranged one-dimensionally or two-dimensionally, and a field of view from the X-ray detection element (the incident angle of an X-ray that can enter the X-ray detection element). A collimator 31b for limiting the range. Furthermore, the detector 31a preferably has an energy decomposition function. By having the energy decomposing function, only X-rays having desired energy can be selected and detected from the X-rays incident on the respective X-ray detection elements, so that noise can be reduced.
  As an example of the detector 31a of the position sensitive detector 31, an X-ray detector in which semiconductor elements are two-dimensionally arranged (for example, a product name PILATUS100K manufactured by DECTRIS Ltd.), or a proportional counter is made one-dimensional. An arrayed X-ray detector (for example, trade name PSPC system manufactured by Rigaku Corporation) can be used.
  FIG. 2 is a partially enlarged cross-sectional view of the total reflection X-ray analyzer according to the first embodiment of the present invention, and shows the positional relationship between the surface of the sample 1 and the position sensitive detector 31 in FIG.
  1 and 2, the collimator 31b has a plurality of (for example, M) flat plate-shaped shielding plates 31c arranged in parallel to each other. The collimator 31b is installed on the lower surface (detection surface) of the detector 31a so that the shielding plate 31c is perpendicular to the paper surface of FIG. That is, the shielding plate 31c is arranged perpendicular to the x axis.
  The collimator 31b limits the surface of the sample 1 that can be viewed from each X-ray detection element of the detector 31a to strip-shaped regions S1 to SM defined by the shielding plate 31c. The longitudinal direction of the strip-shaped regions S1 to SM is perpendicular to the traveling direction of the divergent X-ray beam 3 (perpendicular to the paper surface of FIG. 1). Therefore, the surface of the sample 1 is made up of M strip-shaped regions Sm (lined in the direction of the diverging X-ray beam 3 from the point 1C to the point 1A in FIG. 1; the x-axis direction) by the collimator 31b. m = 1, 2,..., M).
  The collimator 31b separates the fluorescent X-rays 5 emitted from the surface of the sample 1 into fluorescent X-rays 5-m emitted from the strip-shaped regions Sm, and enters the detector 31a. Accordingly, the intensity of the fluorescent X-ray 5 emitted from the surface of the sample 1 is measured for each fluorescent X-ray 5-m emitted from one region Sm defined on the surface of the sample 1. That is, the intensities of the fluorescent X-rays 5-1 to 5-M emitted from the plurality of regions S1 to SM are measured for each region Sm.
  The reflected X-rays 7 reflected from the surface of the sample 1 pass through the X-ray transmission window 62 and are detected by the position sensitive detector 63 disposed outside the champ 60. Of course, the position sensitive detector 63 may be disposed in the chamber 60. The position sensitive detector 63 preferably includes a one-dimensional or two-dimensional detector 63a and a collimator 63b. Thereby, the intensity | strength of the reflected X-ray 3 corresponding to the reflective position (area | region Sm) of the sample 1 surface can be known. It should be noted that an X-ray detector made of a single element may be used in place of the position sensitive detector 63a except when the X-ray absorption amount is measured from the reflectance described later.
  The position sensitive detector 63 detects the reflected X-ray 7 and is arranged so that a part of the position-sensitive detector 63 is on the path of the divergent X-ray beam 3. Thereby, the intensity | strength of the divergent X-ray beam 3 which was not shielded by the sample 1 can be measured. The divergent angle of the divergent X-ray beam 3 is as small as 1 degree or less, and the distance between the divergent X-ray beam 3 and the reflected X-ray 7 is compared with the detection range (the size of the detection surface) of the position sensitive detector 63. And small. For this reason, it is possible to detect both the diverging X-ray beam 3 and the reflected X-ray 7 with one position sensitive detector 63. When the distance between the divergent X-ray beam 3 and the reflected X-ray is large, two position sensitive detectors 63 may be provided or arranged to be movable.
  The output signal of the position sensitive detector 31 is input to the wave height analyzer 31h, and the intensity is integrated for each pixel of the detector 31a and for each energy of the fluorescent X-ray 5. The output signal of the position sensitive detector 63 is input to the counter 63c, and the intensity of the reflected X-ray 7 is integrated for each pixel of the detector 63a.
  In the first embodiment, the transmission X-ray detector 35 that measures the intensity of the divergent X-ray beam 3 is disposed between the divergent X-ray beam former 10 and the sample 1. As a result, even if the intensity variation of the divergent X-ray beam 3 occurs, the X-ray absorption amount calculated from the intensity of the fluorescent X-ray 7 and thus the XAFS data can be obtained accurately.
  The computer 50 is configured by, for example, a commonly used personal computer system. The computer 50 collects data of the position sensitive detectors 31 and 63 and the transmission X-ray detector 35 described above, and executes calculations necessary for calculating changes in the depth direction of the XAFS, and at the same time, the monochromator 11. And it functions as a controller for controlling the holding table 20.
  FIG. 3 is a functional configuration diagram of the computer according to the present invention, and represents main functional units included in the computer. These functions are stored as programs in the memory and storage device of the computer and executed by the CPU of the computer.
  Referring to FIG. 3, the computer 50 includes a divergent X-ray beam control unit 51, a sample posture control unit 52, an intensity measurement control unit 53, an intrusion X-ray intensity distribution calculation unit 55, and an XAFS detection unit 56.
  The divergent X-ray beam control unit 51 controls the divergent X-ray beam former 10. That is, by controlling the rotation angle (rotation direction 11r) of the turntable of the monochromator 11, the wavelength λ of the parallel X-ray beam 2-1 output from the monochromator 11 is set to a plurality of preset wavelengths λk (k = 1, 2,..., N) is controlled so as to be a predetermined wavelength λi. At this time, the positional deviation of the parallel X-ray beam 2-1 caused by the rotation of the turntable is corrected by moving the first crystal 11a in the moving direction 11s. As a result, it is possible to change only the wavelength λ without changing the traveling direction and position of the parallel X-ray beam 2-1.
  The sample posture control unit 52 controls the holding table 20 for the sample 1. That is, the sample attitude control unit 52 controls the rotation angle of the goniometer 20a (the rotation direction 20r and the rotation direction orthogonal thereto) and the height of the base 20b, thereby allowing the position of the surface of the sample 1 relative to the diverging X-ray beam 3 and Control the tilt.
The intensity measurement control unit 53 collects the outputs of the position sensitive detectors 31 and 63 (representing the intensity of the observed X-ray) via the wave height analyzer 31h and the counter 63c, respectively. Further, the output of the transmission X-ray detector 35 (representing the intensity of the measured divergent X-ray beam 3) is collected. Based on the measured intensity of the divergent X-ray beam 3, the intensity I L m of the fluorescent X-ray 5 emitted from the area Sm defined on the surface of the sample 1 is calibrated for all the areas S1 to SM. If necessary, similarly, the intensity I R m of the reflected X-ray 7 reflected from the region Sm is calibrated, and the reflectance Rm of the region Sm is obtained. Accordingly, the intensity I L m and the reflectance Rm of the fluorescent X-ray 5 emitted by irradiation with the divergent X-ray beam 3 having the wavelength λi are functions of the position xm of the region Sm, I L m = I L (xm), Rm = R (xm).
  The penetration X-ray intensity distribution calculation unit 55 includes a visual angle calculation unit 54, and calculates the intensity distribution and penetration depth of the X-rays that enter the sample 1 in the depth direction.
  Based on the posture of the surface of the sample 1 set by the sample posture control unit 52, the visual angle calculation unit 54 is a divergent X-ray beam that is incident on each region Sm of the regions S1 to SM that are set (defined) on the surface of the sample 1. 3 is calculated (see FIG. 2).
Referring to FIG. 2, when the divergent X-ray beam 3 irradiates the surface of the sample 1, the angle formed by the X-rays constituting the divergent X-ray beam 3 with the surface of the sample 1, that is, the viewing angle θ is It differs depending on the incident position (position x in the x-axis direction). For example, of the X-rays constituting the diverging X-ray beam 3, the viewing angle of the X-ray 3m incident on the region Sm is defined as a viewing angle θm. The X-ray viewing angle θm−1 incident on the region Sm−1 adjacent to the left is larger, and θm−1> θm. Further, the X-ray viewing angle θm + 1 incident on the region Sm + 1 adjacent to the right is smaller, and θm> θm + 1. Therefore,
θ1>θ2>...>θm> θm + 1>...> θM (1 formula)
It becomes. In FIG. 2, the X-ray 3m reflected from the region Sm is shown as a reflected X-ray 7m.
The viewing angle θ of X-rays incident on the surface of the sample 1, for example, the viewing angles θ1 to θM in the formula 1, is the center line of the divergent X-ray beam 3 (the focal point 4 and the center point 1B of the surface of the sample 1 in FIG. 1). The line segment indicated by a two-dot chain line connecting the two points depends on the angle θb formed with the surface of the sample 1. For example, if θm = θb (when the center of the divergent X-ray beam 3 is incident on the region Sm)
θm ± 1 = θb ± δθm ± 1 (1 'equation)
As a result, the visual angle θm of all the areas Sm is determined. Where δθm ± 1 is
δθm ± 1 = θm ± 1-θm
And is calculated as the angle at which the region Sm ± 1 is viewed from the focal point 4.
  As will be described later, this angle θb is set to a predetermined angle before measurement, for example, the total reflection critical angle θc, and is maintained at the predetermined angle during measurement. For this reason, the viewing angle θ of X-rays incident on the surface of the sample 1 is determined as a function of the position x and is displayed as θ = θ (x). Therefore, using the x-coordinate position xm of the region Sm, the viewing angle θm of X-rays incident on the region Sm can be displayed as θm = θ (xm).
The intrusion X-ray intensity distribution calculating unit 55 calculates the viewing angle θ (x) calculated by the viewing angle calculating unit 54 and the wavelength λ of the diverging X-ray beam 3 set by the diverging X-ray beam control unit 51. And using the X-ray intensity (intensity distribution) Ip (z) at the depth z from the surface of the sample 1,
Ip = Io × exp (−z / Λ) (Expression 2)
Calculate as Here, Io is the intensity of the incident X-ray (divergent X-ray beam 3), and Λ is the penetration depth. The penetration depth Λ is determined by using the viewing angle θ and the X-ray wavelength λ,
Λ (θ, λ) = (λ / 4π) ×
× √ [2 / {√ ((θ 2 −2δ) + 4β 2 ) − (θ 2 −2δ)}] (Expression 3)
Is calculated as Here, δ and β represent the refractive index n of the sample 1,
n = 1−δ−jβ
And the real part δ and the imaginary part β of the difference when expressed as the difference in refractive index from the vacuum. J is an imaginary unit.
  The viewing angle θ in Equation 3 is given as M viewing angles θm corresponding to the region Sm (m = 1, 2,..., M). As will be described later, N wavelengths λi (i = 1, 2,..., N) are given as the wavelength λi. Therefore, M × N penetration depths Λ (θ, λ) and intensity distribution Ip (z) are calculated.
  The XAFS detection unit 56 calculates the X-ray absorption amount Xab (xm) in the region Sm based on the intensity of the fluorescent X-ray 5 collected and calibrated by the intensity measurement control unit 53 with respect to one wavelength λi. Calculate for S1 to SM. On the other hand, the penetration depth and the intensity distribution of the penetration X-ray in the region Sm are the penetration depth Λ (xm) calculated by the penetration X-ray intensity calculation unit and the penetration X-ray intensity distribution Ip ( xm, z), where z is the depth z from the sample surface. The XAFS detector 56 calculates the X-ray absorption depth direction at the wavelength λi based on the intrusion X-ray intensity distribution Ip (xm, z) and the X-ray absorption amount Xab (xm) calculated for one wavelength λi. The distribution φ (z) is calculated. This is performed for all wavelengths λ1 to λN.
  In the present invention, the distribution φ (z) in the depth direction of X-ray absorption is assumed to be uniform within the surface of the sample 1. The sample 1 is manufactured by forming a uniform layer structure on the entire surface of the sample 1, for example, a laminated structure composed of an ion implantation layer or a ferromagnetic thin film / tunnel barrier film.
In Sample 1, the X-ray absorption amount Xab (xm) is
Xab (xm) = ∫ {Ip (xm, z) × φ (z)} dz (Formula 4)
Represented as: Here, the integration range starts at z = 0 and reaches a depth at which X-ray absorption can be ignored.
  The XAFS detection unit 56 obtains an unknown function φ (z) using the measured Xab (xm) and the calculated Ip (xm, z) as known functions. For example, an approximate solution of the function φ (z) is obtained by the inverse calculation of the four formulas or by trial and error.
As an example, Ip (xm, z) and φ (z) are approximated by a linear expression of a function sequence tn (n = 1, 2,...) Forming a completely orthogonal system, and substituted into Expression 4,
Xab (xm) = Σn (Ip, m, n × φn) (4 ′ equation)
Get. Here, Ip, m, n and φn are n-th order coefficients when Ip (xm, z) and φ (z) are expanded by the function sequence tn, respectively. Φn can be obtained from the equation 4 ′ using the method of least squares. That is,
Σm {Xab (xm) −Σn (Ip, m, n × φn)} 2
Φn that minimizes is calculated. As a result, the approximate expression of the unknown function φ (z) is
φ (z) = Σn (φn × tn (z)).
As another example, the X-ray absorption amount Xab (xm) is expressed by using the penetration depth Λ (xm).
Xab (xm) = Xab (xm-1) +
+ Ip (xm, z = Λm) × φ (z = Λm)) × ΔΛm (Formula 5)
It expresses. Here, Λm is the penetration depth Λ (xm) in the region Sm, and ΔΛm is ΔΛm = Λ (xm) −Λ (xm−1). Therefore, based on Equation 5, the X-ray absorption amount of the layer (thickness ΔΛm) located at a depth near Λm can be obtained as the difference between the X-ray absorption amounts of the adjacent regions Sm−1 and Sm. From this, the distribution φ (z) in the depth direction of X-ray absorption is calculated.
  Of course, the X-ray absorption distribution φ (z) in the depth direction is obtained from the measured X-ray absorption amount Xab and the calculated penetration X-ray intensity distribution Ip (xm, z) using a method other than this. Also good.
  Further, the XAFS detection unit 56 calculates a distribution φ (z) in the depth direction of X-ray absorption for all wavelengths λ1 to λN. Thereby, the wavelength λ dependency of the X-ray absorption amount, that is, XAFS data is calculated. At this time, the distribution in the depth direction of the XAFS data is acquired. In other words, the XAFS of the layer located at an arbitrary depth z is acquired.
  Next, the measurement process of the total reflection X-ray analysis method of 1st Embodiment of this invention is demonstrated.
  FIG. 4 is a measurement process diagram (No. 1) according to the first embodiment of the present invention, showing a process from formation of a divergent X-ray beam to measurement of fluorescent X-ray intensity to detection of a change in XAFS. .
  Referring to FIG. 4, in step S0, divergent X-ray beam control unit 51 sets a numerical value i = 0 indicating initial setting in a register. In step S1, a divergent X-ray beam 3 having a wavelength λ0 set in advance as the i = 0th wavelength is formed in accordance with the register value i = 0. In step S1, an X-ray tube can be used as the light source instead of the emitted light. At this time, an initial wavelength λ0 is selected from X-rays having a continuous wavelength distribution generated by bremsstrahlung. As the wavelength λ0, for example, a wavelength near the CuKα line may be selected. In addition, when performing step S2 mentioned later using synchrotron radiation, the wavelength used for XAFS analysis, for example, the wavelength which has an energy of 11.9 KeV, is selected.
  FIG. 5 is a measurement process diagram (part 2) according to the first embodiment of the present invention, and shows the detailed process of step S1.
  Referring to FIGS. 5 and 1, divergent X-ray beam control unit 51 (see FIG. 3) has rotating table (first and second crystals 11 a and 11 b) of monochromator 11 placed in step S <b> 11. ) Is rotated so that the X-ray of wavelength λ0 satisfies the Bragg angle. As a result, a monochromatic parallel X-ray beam 2-1 having a wavelength λ0 is output from the monochromator 11.
  Next, in step S12, the divergent X-ray beam control unit 51 moves the second crystal 11b in the moving direction 11s (vertical direction of the first crystal) so that the center of the parallel X-ray beam 2-1 becomes a predetermined position. Adjust to.
  Next, referring to FIG. 4, step S2 is executed to set the position and orientation of the sample.
  FIG. 6 is a measurement process diagram (part 3) according to the first embodiment of the present invention, and shows the detailed process of step S2.
  Referring to FIG. 6, in step S2, first, in step S21, the surface of sample 1 is aligned with the center of the divergent X-ray beam.
  Specifically, referring to FIG. 1, first, a part of the position sensitive detector 63 causes the center line of the diverging X-ray beam 3 (in FIG. 1, the focal point 4 and the center point of the sample 1 surface). It is arranged so as to extend over the extension of a straight line (dotted line connecting B). Thereby, the intensity of the entire divergent X-ray beam 3 is measured by the position sensitive detector 63. The sample 1 is placed on the holding table 20 and held horizontally. That is, the surface of the sample 1 is held parallel to the xy plane.
  In step S21, the sample posture control unit 52 raises the base 20b in the z direction, and the position where the sample 1 blocks the divergent X-ray beam 3 to half, that is, the divergent X-ray beam observed by the position sensitive detector 63. The sample 1 is moved to a height at which the X-ray intensity of 3 becomes 1/2. Next, in step S22, the sample posture control unit 52 rotates the goniometer 20a in the xz plane (rotation direction 20r) and sets the rotation position at which the X-ray intensity of the divergent X-ray beam 3 is maximized. Next, in step S23, when the sample posture control unit 52 determines that the surface of the sample 1 is located on the center line of the divergent X-ray beam, it executes step S24. Repeat S23. Note that the determination that the surface of the sample 1 is located on the center line is made when the rotational position at the end of step S22 is at the minimum position of the X-ray intensity. As described above, the surface of the sample 1 is set in a plane including the center line of the divergent X-ray beam 3 by alternately repeating the raising of the base 20b and the rotation of the goniometer 20a.
  Next, steps S24 and S25 are executed. In steps S24 and S25, the viewing angle of the divergent X-ray beam 3 incident on the sample 1 is set. That is, the inclination of the sample 1 is set so that X-rays traveling along the center line of the divergent X-ray beam 3 are incident at a viewing angle near the total reflection critical angle θc.
  First, in step S24, with reference to FIG. 1, the sample attitude control unit 52 rotates the goniometer 20a in the rotation direction 20r, and the angle (hereinafter referred to as “sight-lighting”) that the center line of the diverging X-ray beam 3 makes with the surface of the sample 1. (The angle θb ”) is scanned (the viewing angle θb is equal to the rotation angle of the goniometer 20a from step S1). Then, the intensity of the reflected X-ray 7 reflected from the surface of the sample 1 is observed using the position sensitive detector 63. Next, in step S25, the intensity of the reflected X-ray 7 at the center of the surface of the sample 1 (the area in the vicinity of the point 1B in FIG. 1) is ½ of the intensity of the divergent X-ray 3, that is, the reflectance is The viewing angle θb is set to be 0.5.
  The center part of the surface of the sample 1 can be obtained as the center of both ends (upper and lower ends in FIG. 1) of the reflected X-ray 7 with reference to FIG. This is because both ends of the reflected X-ray 7 correspond to reflection from both ends (points 1A and 1C shown in FIG. 1) of the divergent X-ray beam 3 irradiated on the surface of the sample 1. In this specification, the point 1B where the center line of the divergent X-ray beam 3 and the surface of the sample 1 intersect is described as the center of the sample 1 surface.
  In the steps S21 to S25 described above, a predetermined wavelength λ0 can be set from X-rays having a continuous wavelength generated using an X-ray tube. In this case, in step S1, the predetermined wavelength λ0 is selected as described above. Further, the emitted light may be set as the incident X-ray beam 2.
  FIG. 7 is a diagram showing the relationship between the reflection intensity and the viewing angle, and shows the change in X-ray reflectivity when the viewing angle θ is scanned. FIG. 7 shows calculated values for CuKα rays.
  Referring to the curve R in FIG. 7, when the visual angle θ is scanned from 0 degree to 0.5 degree, the reflectance R is approximately 1 when the visual angle θ is in the range of 0 degree to 0.2 degree. 0, indicating total reflection. In the range of the viewing angle θ = 0.2 degrees to 0.25 degrees, the reflectance decreases rapidly, and at 0.25 degrees or more, the reflectance gradually decreases to 0.1 or less, and total reflection does not occur. When the viewing angle θ is equal to the total reflection critical angle θc, the reflectance R becomes 0.5.
  The viewing angle θb formed by the center line of the diverging X-ray beam 3 and the surface of the sample 1 is equal to the rotation angle of the goniometer 20a. Therefore, by setting the goniometer 20a at the rotational position where the intensity of the reflected X-ray 7 becomes half the intensity of the divergent X-ray 3, the viewing angle θb of the divergent X-ray beam 3 incident on the center of the surface of the sample 1 is set. Can be set to the total reflection critical angle θc.
  In FIG. 7, the observed apparent reflectance Rob, the calculated X-ray intensity T of the sample 1 surface, and the calculated X-ray penetration depth Λ are displayed together. The apparent reflectance Rob calculated from the observed intensity of the reflected X-ray 7 decreases at a viewing angle θ that is equal to or smaller than θcut. This is because the divergent X-ray beam 3 protrudes from the sample 1. In this case, since the divergent X-ray beam 3 irradiates the end surface of the sample 1, noise increases. For this reason, it is preferable that the viewing angle θb is equal to or greater than θcut. The X-ray intensity T on the surface of the sample 1 has a peak near the total reflection critical angle θc. This peak is caused by interference between the divergent X-ray beam 3 and the reflected X-ray 7. The X-ray intensity distribution of the X-rays that enter the sample 1 is calculated in consideration of this interference.
  The penetration depth Λ of X-rays is calculated as a function of the viewing angle θ according to Equation 3, and changes rapidly in the vicinity of the total reflection critical angle θc with reference to the curve Λ in FIG. In step S2, the visual angle θb at the point 1B is set in the vicinity of the total reflection critical angle θc. For this reason, in the region Sm near the point 1B, a slight difference in the viewing angle causes a large change in the penetration depth Λ. As a result, the penetration depth Λ changes sharply according to the variation of the visual angle θ, that is, according to the position of the region Sm. Further, the X-ray intensity T on the surface of the sample 1 also changes suddenly near the total reflection critical angle θc. Therefore, the intrusion X-ray intensity distribution Ip also varies abruptly at the viewing angle near the total reflection critical angle. Thus, when the visual angle θb is set in the vicinity of the total reflection critical angle θc, the penetration depth and the penetration X-ray intensity distribution change suddenly with respect to the change in the visual angle θ, and thus the depth distribution of the X-ray absorption amount. It is possible to accurately detect the difference in the depth distribution of the X-ray absorption amount.
  For X-rays with different wavelengths, the horizontal axis of FIG. 7 is represented as a normalization angle θ by the total reflection critical angle θc. Therefore, other wavelengths are also explained in the same manner as in FIG. 7 using normalized diagrams.
  When the steps S21 to S25 described above are set by the divergent X-ray beam 3 having a wavelength different from that of the XAFS measurement, the divergent X-ray beam having a wavelength suitable for the XAFS measurement, for example, a wavelength having an energy of 11.9 keV is used again. Run. Thereby, in the XAFS measurement, it is possible to adjust the visual angle θm to the region Sm located substantially in the center of the sample 1 to the total reflection critical angle θc. Of course, when the steps S21 to S25 are performed with a wavelength suitable for XAFS measurement from the beginning, such adjustment is unnecessary.
  After adjustment with synchrotron radiation, the viewing angle θb that the center line of the divergent X-ray beam 3 makes with the surface of the sample 1 is the total reflection critical angle θc = 0.151 degrees of the sample (Si) at a wavelength having an energy of 11.9 keV. Has been adjusted. On the other hand, the divergence angle of the divergent X-ray beam 3 is 0.122 degrees, and the divergent X-ray beam 3 is an area having a length of 82 mm in the x-axis direction on the surface of the sample 1 (between points 1C to 1A in FIG. 1). Area).
  Referring again to FIG. 4, after step S <b> 2 ends, in step S <b> 3, the visual angle calculation unit 54 calculates the visual angle θm of the divergent X-ray beam 3 incident on each region Sm.
  Referring to FIGS. 1 and 2, at the end of step S2, the viewing angle θm of the divergent X-ray beam 3 incident on the region Sm near the center of the surface of the sample 1 (near point 1B in FIG. 1) is, for example, The total reflection critical angle θc for X-rays having an energy of 11.9 keV is set. The viewing angle calculation unit 54 sets the viewing angle θm of the region Sm as θm = θc, and uses this as a reference, according to the formula 1 ′, the region Sm−1 on the left side (the side on which the diverging X-ray beam 3 is incident). ,..., S1 are incident angles θm−1,..., Θ1 and right-side regions Sm + 1,. Since the region Sm that gives the total reflection critical angle θc can be accurately determined as the region Sm having the reflectance R = 0.5, the visual angle θm of all the other regions Sm can be accurately calculated. it can.
  After the end of step S3, the wavelength of the divergent X-ray beam 3 is changed and measurement of the secondary radiation emitted from the surface of the sample 1, in this case, the intensity of fluorescent X-ray 5 is started. First, in step S0-1, the register value is set to i = 1.
  Next, in step S4, the divergent X-ray beam control unit 51 controls the rotation of the turntable of the monochromator 11 similarly to step S11, and the X-ray having the wavelength λi (initially i = 1) has the Bragg angle. Rotate to fill. As a result, the monochromatic parallel X-ray beam 2-1 having the wavelength λi is output from the monochromator 11. Radiant light is used as the incident X-ray beam 2. The wavelength λi is selected in the vicinity of the absorption edge wavelength of the element to be measured. Here, in order to measure the X-AFS near the K-absorption edge wavelength of As and 11.867 keV, N wavelengths are set in advance within the energy range of 11.8 keV to 12.2 keV, and one of them is selected. Selected. By this step S4, the wavelength of the divergent X-ray beam 3 is changed. However, the position and traveling direction of the divergent X-ray beam 3 do not change.
  Next, referring to FIG. 4, in step S5, the intensity of the secondary radiation emitted from the surface of the sample 1, in this case, the fluorescent X-ray 5 is measured. Referring to FIGS. 1 and 2, intensity measurement controller 53 uses position sensitive detector 31 to measure the intensity of fluorescent X-rays 5 emitted from regions S <b> 1 to SM defined on the surface of sample 1. The intensity of the fluorescent X-ray 5 is measured as the intensity emitted from each of the M areas S1 to SM defined on the surface of the sample 1 by the collimator 31b. That is, the fluorescent X-rays 5-m (m = 1, 2,..., M) emitted from the region Sm are measured for all the regions S1 to SM.
  FIG. 8 is a diagram for explaining the energy decomposition function of the detector, and represents the X-ray signal intensity measured by the position sensitive detector 31 and its energy. The signal intensity represents the intensity of X-rays radiated from one region Sm, and the energy of the X-rays was displayed by the channel of the pulse height analyzer 31h.
  Referring to FIG. 8, two peaks corresponding to two energy ranges 71 and 72 were observed in the signal intensity of X-rays emitted from the surface of sample 1. The peak in the energy range 71 is the fluorescent X-ray 5 of As, which is radiation from As in the sample 1 that is the observation target of the first embodiment. The peak in the energy range 72 is the elastic scattered X-ray of the diverging X-ray beam 3. The intensity measurement control unit 53 measures only the signal measured by the channel within the energy range 71, and selects and measures the intensity of the fluorescent X-ray 5 of As that is the observation target. Thus, by providing the position sensitive detector 31 with energy resolution, it is possible to reduce noise caused by scattered X-rays or fluorescent X-rays of elements not observed.
  Referring to FIG. 4, in step S4, the visual angle calculation unit 54 calculates the visual angle θm for each region Sm.
  Next, the intrusion X-ray intensity calculation unit 55 calculates the viewing angle θm calculated by the viewing angle calculation unit 54 and the wavelength λi of the diverging X-ray beam 3 selected by the diverging X-ray beam control unit 51 using two formulas and 3 Substituting into θ and λ in the equation, the X-ray intensity Ip (z) at the penetration depth Λ and the depth z is calculated. The penetration depth Λ and the X-ray intensity Ip (z) are calculated for each of the M regions S1 to SM for one wavelength λi. Accordingly, Λ (xm) and Ip (xm, z) can be displayed using the x coordinate xm of the region Sm.
  FIG. 9 is a diagram showing the viewing angle dependency of the penetration depth according to the first embodiment of the present invention. The penetration X-ray intensity calculation unit 55 calculates X-rays having energy of 11.9 keV. It represents the penetration depth. Note that θ1A, θ1B, and θ1C in FIG. 9 are the viewing angles θ toward the regions S1, Sm, and SM including the points 1A, 1B, and 1C in FIG.
  Referring to FIG. 9, penetration depth Λ gradually increases with increase in viewing angle when viewing angle θ is equal to or smaller than θ1A. When the visual angle θ is in the vicinity of the total reflection critical angle θc, it deepens rapidly. At a viewing angle of θ1C or more, it gradually becomes deep as the viewing angle θ increases.
  The viewing angle θ1B of the central region Sm of the sample 1 is equal to the total reflection critical angle θc, and the penetration depth Λ (xm) in this region Sm was calculated to be 20 nm. On the other hand, the viewing angle θ1A of the region S1 located at one end of the divergent X-ray beam 3 was 0.105 degrees, and the penetration depth of this region S1 was calculated to be less than 4 nm. The viewing angle θ1C of the region SM located at the other end of the divergent X-ray beam 3 was 0.227 degrees, and the penetration depth of this region S1 was calculated to be approximately 200 nm. The distance between the regions S1 to SM irradiated with the divergent X-ray beam 3 on the surface of the sample 1 (distance between points 1A to 1C in FIG. 1) was 82 mm.
  FIG. 10 is a diagram showing the intensity distribution of the intrusion X-ray calculated in the first embodiment, and the depth direction of the X-ray (intrusion X-ray) intensity in the sample 1 calculated by the intrusion X-ray intensity calculation unit 55. Represents the distribution of.
  Referring to FIG. 10, the intrusion X-ray intensity Ip decreases with an exponential function of depth z in the depth z direction according to the two equations. The decrease rate dIp / dz of the X-ray intensity Ip with respect to the depth near the surface (near z = 0) depends on the size of the penetration depth Λ. With reference to the curve IA, in the region S1 where the penetration depth Λ is small, it rapidly decreases. On the other hand, referring to the curve IC, in the region SM where the penetration depth Λ is large, it gradually decreases compared to the curve IA. Note that the X-ray intensity Ip on the surface changes due to the interference between the divergent X-ray beam 3 and the reflected X-ray beam 7, and takes different intensity for each viewing angle θm, that is, for each region Sm.
  Next, referring to FIG. 4, in step S 7, the register content i of the divergent X-ray beam control unit 51 is examined, and when i is less than the number N of wavelengths to be selected as the divergent X-ray beam 3, It is determined that the wavelength is not selected, and after setting i = i + 1 in step S0-2, steps S1 to S6 are repeated again.
  When the register content i matches the given number N, it is determined that all wavelengths have been measured, and the next step S8 is executed. Before the execution of step S8, the penetration depth Λ and the penetration X-ray intensity distribution Ip (z) are set to N wavelengths for each of the M regions Sm (m = 1,..., M). It is calculated for λi (i = 1,..., N). That is, the functions Λ (λi, xm, z) and Ip (λi, xm, z) with the wavelength λi and the x coordinate xm of the region Sm as parameters are calculated.
  In step S8, the XAFS detection unit 56 calculates the X-ray absorption amount Xab (xm) absorbed in the region Sm based on the intensity of the fluorescent X-ray 5 emitted from the region Sm measured by the intensity measurement unit in step S5. calculate. The X-ray absorption amount Xab (xm) is calculated for each region where m is 1 to M and for each wavelength where i = 1 to N. Accordingly, the X-ray absorption amount Xab (xm) is expressed as a function Xab (xm, λi) of the region position xm and the wavelength λi.
  Further, the XAFS detection unit 56 calculates the calculated X-ray absorption amount Xab (xm, λi) and the intrusion X-ray intensity distribution Ip (λi, xm, z) calculated by the intrusion X-ray intensity measurement unit 55 in step S5. Are substituted into equations (4) to (4 ′) to obtain the X-ray absorption amount φ (z) of the layer having the depth z for each wavelength λi (i = 1,..., N). In other words, the wavelength dependence of the X-ray absorption amount φ (z) of the layer having the depth z, that is, the XAFS of the layer having the depth z is required. Therefore, it is possible to know the state of an atom to be observed at an arbitrary depth z, for example, the state of As, such as the coordination, density, and chemical bonding state. Thus, in step S8, a change in XAFS in the depth direction is detected and calculated.
  In the first embodiment of the present invention described above, the posture (height and tilt) of the sample 1 is set once as an initial setting in step S2, and the tilt of the sample 1 is not changed thereafter. Then, the X-ray absorption amount is measured for a plurality of wavelengths of the diverging X-ray beam 3, and the wavelength dependency of the X-ray absorption amount of the layer at an arbitrary depth z, that is, XAFS data is acquired.
Therefore, the time t required to acquire XAFS data is
t = tθo + N × (tλset + tob) (Expression 6)
It becomes. Here, tθo is a time spent for setting (initial setting) the inclination of the sample 1 once, tλset is a time spent for changing the wavelength of the divergent X-ray beam 3 once, and tob is an intensity of the fluorescent X-ray 5 Measurement time. N is the number of wavelengths selected by the divergent X-ray beam 3.
  On the other hand, in the conventional total reflection X-ray analysis method shown as a comparative example, the inclination of the sample 1 is executed a plurality of times for one wavelength.
  FIG. 11 is a cross-sectional view of the total reflection X-ray analysis apparatus of the comparative example, and shows the main mechanism near the sample 1 of the total reflection X-ray analysis apparatus 200 used in the total reflection X-ray analysis method of the comparative example.
  Referring to FIG. 11, in the total reflection X-ray analysis apparatus 200 of the comparative example, the X-ray beam 201 is a parallel beam, the detectors 202 and 203 are composed of a single detection element, and are not position sensitive. Except for this, it is the same as the total reflection X-ray analyzer 101 of the first embodiment. In order to form the parallel X-ray beam 201, a plane mirror is used instead of the reflecting mirror 12 of FIG. Alternatively, the reflecting mirror 12 is not used.
  In the total reflection X-ray analysis method of the comparative example, the surface of the sample 1 is irradiated with a parallel X-ray beam 201 having a wavelength λi, and the fluorescent X-ray 5 emitted from the surface of the sample 1 is detected by the detector 202. Next, the goniometer 2b is adjusted to incline the sample 1, sequentially changing the viewing angle θ of the X-ray beam 201, and the fluorescent X-rays 5 at the respective viewing angles θk (k = 1,..., M). Measure strength. Furthermore, the wavelength λi is changed N times, and the measurement of the intensity of the fluorescent X-ray is repeated while changing the viewing angle θ for each wavelength. Thereby, XAFS data of layers having different viewing angles, in other words, different depths z are acquired.
In the total reflection X-ray analysis method of this comparative example, it is necessary to change the inclination of the sample 1 M times and measure the M fluorescent X-ray intensity for one wavelength. The time required for measurement at one inclination is the sum of the time tθset required for setting the inclination and the measurement time t′ob of the fluorescent X-ray intensity, tθset + t′ob. Therefore, the time t ′ required to acquire the XAFS data is
t ′ = tθo + N × (tλset + M × (tθset + t′ob))
= Tθo + N × (tλset + M × (tθset + tob / M)) (Expression 7)
It is expressed. Here, the measurement time t′ob of the fluorescent X-ray intensity of the comparative example was set to t′ob = tob / M, which is the time obtained by dividing the measurement time tob of the first embodiment by the number M of the regions Sm. If it does in this way, the measurement number of a fluorescent X-ray will become substantially the same with a prior art example and this 1st Embodiment, and equivalent intensity | strength measurement precision will be obtained.
Subtract 6 from 7 and
t′−t = N × M × tθset (Equation 8)
Get. Equation 8 means that the XAFS measurement time of the first embodiment is shortened by N × M × tθset compared to the total reflection X-ray analysis method of the comparative example.
  For example, if the number of wavelengths N = 100, the number of regions M = 20, and the time required for the inclination of the sample 1 tθset = 6 seconds, t′−t = 12000 seconds = 3.3 hours. Therefore, according to the first embodiment, the analysis time can be shortened by 3 hours or more compared to the total reflection X-ray analysis method of the comparative example.
  The second embodiment of the present invention relates to a total reflection X-ray analysis method for measuring the intensity of photoelectrons emitted from a sample surface, for example, Auger electrons, using a position sensitive detector.
  FIG. 12 is a cross-sectional view of the total reflection X-ray analyzer according to the second embodiment of the present invention, showing the configuration of the position sensitive detector 32 for detecting photoelectrons.
  Referring to FIG. 12, in the total reflection X-ray analysis apparatus 102 used in the second embodiment, a position sensitive detector that detects fluorescent X-rays used in the total reflection X-ray analysis apparatus 101 of the first embodiment. Instead of 31, a position sensitive detector 32 that detects the photoelectrons 6 is used. The other configurations of both apparatuses 102 and 101 are the same.
  The position sensitive detector 32 used in the total reflection X-ray analyzer 102 includes a one-dimensional or two-dimensional detector 32a and a collimator 32b provided on the lower surface (detection surface) of the detector 32a.
  The collimator 32b includes shielding plates 32c parallel to each other and arranged perpendicular to the x-axis, that is, perpendicular to the surface of the sample 1. The collimator 32b is arranged similarly to the collimator 31b of the first embodiment, and divides and defines the surface of the sample 1 into M areas Sm. That is, the secondary radiation (photoelectron 6 in the second embodiment) emitted from the surface of the sample 1 is separated for each secondary radiation emitted from each region Sm by the shielding plate 32c and detected by the detector 32a.
  The detector 31a is provided with electrodes 32d arranged one-dimensionally or two-dimensionally on the detection surface (lower surface in FIG. 12). These electrodes 32d are arranged so as to be positioned between the shielding plates 32c, and a negative voltage is applied via the galvanometer 31e.
  The steps of the total reflection X-ray analysis method of the second embodiment are the same as those of the first embodiment except for the step of measuring the secondary radiation intensity in step S5 with reference to FIG. For the sake of simplicity, the difference in step S5 will be mainly described below.
  Referring to FIG. 12, in the second embodiment, the intensity of photoelectrons 6 emitted from the surface of sample 1 irradiated with divergent X-ray beam 3 is measured. Photoelectrons 6 emitted from the surface of the sample 1 enter the collimator 32b from below. At this time, the photoelectrons 6 jump into the space immediately above the emission position in the space sandwiched between the shielding plates 32c, and ionize the He atoms 64 in the atmosphere. The ionized He atoms 64 are attracted to the electrode 32d to which a negative potential is applied and are discharged. The electric discharge is detected by the galvanometer 31e, and further, referring to FIG. 1, the energy and intensity are measured by the wave height analyzer 31h.
  Hereinafter, by using the photoelectron intensity instead of the fluorescent X-ray intensity, it is possible to detect a change in the distribution in the depth direction of the XAFS by the same process as in the first embodiment.
  The third embodiment of the present invention relates to a total reflection X-ray analysis method for measuring a reflected X-ray intensity using a position sensitive detector.
  FIG. 13 is a cross-sectional view of a total internal reflection X-ray analyzer according to a third embodiment of the present invention, showing the main configuration.
  Referring to FIG. 13, the total reflection X-ray analyzer 103 used in the third embodiment is secondary radiation emitted from the surface of the sample 1 as compared with the total reflection X-ray analyzer 101 of the first embodiment. This is different in that it does not include the position sensitive detector 31 for detecting the wave height and the wave height analyzer 31h. Further, a position sensitive detector 63 for detecting the reflected X-ray 7 and its wave height analyzer 63h are provided. The rest is the same as the total reflection X-ray analysis apparatus 101 of the first embodiment.
  The process of the total reflection X-ray analysis method of the third embodiment refers to FIG. 4 and uses the reflected X-ray intensity instead of measuring the fluorescent X-ray intensity in the secondary radiation intensity measurement process of step S5. Except for measuring and calculating the X-ray absorption amount based on the reflected X-ray intensity instead of the fluorescent X-ray intensity in step S8, the same as in the first embodiment. For the sake of simplicity, the difference between step S5 and step S8 will be mainly described below.
  In step S5 of the third embodiment, with reference to FIG. 13, the intensity of the reflected X-ray 7 reflected from the surface of the sample 1 by using the position sensitive detector 63 is measured with reference to FIG. . Similar to the position sensitive detector 63 of the first embodiment, the position sensitive detector 63 of the second embodiment includes a collimator 63b and a one-dimensional or two-dimensional detector 63a. Unlike the first embodiment, a single detection element is not used in the third embodiment.
  The collimator 63b selects the reflected X-rays 7 reflected from the surface of the sample 1 for each region Sm defined on the surface of the sample 1, and enters the detector 63a. Accordingly, the intensity of the reflected X-ray 7 for each region Sm is measured. The region Sm is a surface defined on the sample surface by the collimator 63b as a region where the reflected X-rays 7 from the region Sm can enter the detection element of the detector 63a. Therefore, the position sensitive detector 63 measures the reflected X-ray 7 intensity reflected from each region Sm.
  In step S8 in the third embodiment, the X-ray absorption amount is calculated from the reflected X-ray intensity 7 using the Kramers-Kronig relational expression instead of the fluorescent X-ray intensity. Otherwise, the XAFS depth distribution is calculated in the same manner as in step S8 of the first embodiment.
  The fourth embodiment of the present invention relates to a total reflection X-ray analysis method for forming a divergent X-ray beam 3 using a point or linear X-ray source and a curved monochromator.
  FIG. 14 is a configuration diagram of a divergent X-ray beam former according to the fourth embodiment of the present invention, and represents a main configuration of a divergent X-ray beam former 10A of the total reflection X-ray analyzer used in the fourth embodiment. ing.
  Referring to FIG. 14, a divergent X-ray beam former 10A according to the fourth embodiment receives X-rays emitted from an X-ray source 9 in a point or line shape (a line shape perpendicular to the paper surface of FIG. 14). Used as a line beam 2. The X-ray source 9 is realized by, for example, an X-ray tube that generates X-rays by irradiating the surface of a metal target with an electron beam. In addition, when using a linear X-ray source, the solar slit 13 which restrict | limits the divergence direction of the incident X-ray beam 2 to the surface parallel to the paper surface of FIG. 14 is used.
  The incident X-ray beam 2 radiated from the X-ray source 9 enters the curved monochromator 16 and is collected on the focal point 4. This focal point 4 position varies depending on the wavelength. Accordingly, by disposing the slit plate 10a having an opening at the focal point 4 position where the X-rays with a specific wavelength are condensed, only X-rays with a predetermined wavelength can be selectively transmitted. The condensed incident X-ray beam 2 having a predetermined wavelength is further emitted as a diverging X-ray beam 3 that diverges from the focal point 4. The curved monochromator 16 may be a single crystal plate, for example, a graphite single crystal plate that is curved so that the radius of curvature can be adjusted.
  The total reflection X-ray analysis apparatus used in the fourth embodiment described above is the same as the total reflection X-ray analysis apparatus of the first to third embodiments except that the divergent X-ray beam former 10A is different. Also, the total reflection X-ray analysis method of the fourth embodiment is performed in the same process as the first to third embodiments except for the process of forming the divergent X-ray beam 3. According to the fourth embodiment, since no radiant light is used, X-ray analysis using a simple apparatus in the laboratory is realized.
  The fifth embodiment of the present invention relates to a total reflection X-ray analysis method for forming a divergent X-ray beam 3 using a point or line light source and a flat monochromator.
  FIG. 15 is a configuration diagram of a divergent X-ray beam former according to the fifth embodiment of the present invention, and shows a main configuration of a divergent X-ray beam former 10B of the total reflection X-ray analyzer used in the fifth embodiment. ing.
  Referring to FIG. 15, the divergent X-ray beam former 10B of the fifth embodiment is similar to that of the fourth embodiment from a point or linear (linear shape perpendicular to the paper surface of FIG. 14) X-ray source 9. The emitted X-ray is used as the incident X-ray beam 2.
  The incident X-ray beam 2 radiated from the X-ray source 9 passes through the solar slit 13 and enters the flat monochromator 16, and X-rays having a wavelength satisfying the Bragg condition are reflected as diffracted X-rays 18. The diffracted X-ray 18 constitutes a divergent X-ray beam 3 that diverges with the mirror image 9 ′ of the X-ray source 9 formed with the reflecting surface of the flat monochromator 17 as a mirror surface as a focal point 4. Accordingly, a divergent X-ray beam 3 similar to that in the fourth embodiment is formed. Furthermore, in order to reduce noise by limiting the divergence angle in the xz plane of the divergent X-ray beam 3 spreading in a fan shape with the mirror image 9 ′ of the X-ray source 9 as a focal point, a solar slit 14 for limiting the divergence angle in the xz plane. Is preferably provided.
  The divergent X-ray beam 3 formed by the flat monochromator 17 has a different wavelength of diffraction depending on the reflection position of the flat monochromator 17. Accordingly, a wavelength distribution is generated in the direction crossing the divergent X-ray beam 3. Usually, since the divergence angle of the divergent X-ray beam 3 is as small as 0.2 degrees or less, this wavelength distribution can be ignored in the XAFS analysis. Of course, with reference to FIG. 1, the wavelength dependence of the X-ray absorption amount can also be precisely measured by calculating the wavelength of X-rays incident on the region Sm on the surface of the sample 1.
  The fifth embodiment described above is the same as the fourth embodiment and the apparatus and process, except that the divergent X-ray beam former 10B is different. The fourth embodiment also realizes X-ray analysis with a simple apparatus in the laboratory.
  By applying the present invention to XAFS analysis of a sample surface having a distribution in the depth direction, rapid analysis can be realized.
DESCRIPTION OF SYMBOLS 1 Sample 2 Incident X-ray beam 2d Advancing direction 3 Divergent X-ray beam 4 Focus 5, 5-1-5-M Fluorescence X-ray 6 Photoelectron 7 Reflected X-ray 9 X-ray source 9 'Mirror image 10, 10A, 10B Divergent X-ray Beamformer 10a, 10b Slit 11, 16, 17 Monochromator 11a First crystal 11b Second crystal 11r, 20r Rotating direction 11s Moving direction 12 Reflector 13, 14 Solar slit 16 Curved monochromator 17 Flat plate monochromator 20 Holding stand 20a Goniometer 20b Base 31, 32, 63 Position sensitive type detector 31a, 32a, 63a Detector 31b, 32b, 63b Collimator 31c, 32c Shield plate
31h, 63h Wave height analyzer 32d Electrode 32e Galvanometer 35 Transmission X-ray detector 50 Computer 51 Divergent X-ray beam control unit 52 Sample attitude control unit 53 Intensity measurement control unit 54 Visual angle calculation unit 55 Intrusion X-ray intensity calculation Part 56 XAFS detection part 60 Chamber 60a Gas inlet 60b Gas outlet 61, 62 X-ray transmission window 63c Counter 64 He atoms 101, 102, 103, 200 Total reflection X-ray analyzer S1, S2,..., Sm , ..., SM area

Claims (6)

  1. Forming a divergent X-ray beam having a single wavelength selected from a plurality of wavelengths and consisting of X-rays emanating from a linear or point-like focal point;
    A second step of irradiating the sample surface with the divergent X-ray beam such that a part of the X-rays constituting the divergent X-ray beam are incident on the sample surface at a total reflection critical angle;
    A third step of calculating, for each of the regions, a viewing angle of the X-ray incident on each of the plurality of regions defined on the sample surface;
    A fourth step of measuring the intensity of fluorescent X-rays emitted from each region, the intensity of photoelectrons or the intensity of reflected X-rays reflected from each region using a position sensitive detector;
    A fifth step of calculating, for each of the regions, an X-ray intensity distribution in the depth direction of the X-rays that enter the sample from the calculated viewing angle;
    The wavelength of the X-ray is changed to another single wavelength selected from the plurality of wavelengths, the fourth to fifth steps are repeated, and the fluorescent X-rays for the plurality of wavelengths for each region, A sixth step of measuring the intensity of the photoelectrons or the reflected X-rays and calculating the X-ray intensity distribution for the plurality of wavelengths for each region;
    Based on the intensity of the fluorescent X-rays, the photoelectrons or the reflected X-rays measured in the sixth step, and the X-ray intensity distribution calculated in the sixth step, an X-ray absorption fine structure (XAFS) ) Calculating the depth direction distribution of the sample,
    A total reflection X-ray analysis method comprising:
  2. The position sensitive detector has an energy decomposition function,
    The total reflection X-ray analysis method according to claim 1, wherein the third step measures the intensity of fluorescent X-rays, photoelectrons or reflected X-rays in a given energy range.
  3. The first step includes
    Incident X-rays of a parallel beam having a continuous wavelength are incident on a parallel plate monochromator and spectrally separate the X-rays of the single wavelength;
    Entering the spectroscopic X-rays into a reflecting mirror and condensing them into a linear or point-like focal point;
    The total reflection X-ray analysis method according to claim 1, wherein:
  4. The first step includes
    Incident X-rays having a continuous wavelength are incident on a curved monochromator and condensing the X-rays having the single wavelength on a linear or point-like focal point;
    Disposing a slit plate having an opening at the focal point, and passing only the X-ray having the single wavelength through the opening;
    The total reflection X-ray analysis method according to claim 1, wherein:
  5. The first step includes
    An incident X-ray beam emitted from a point or line light source and having a continuous wavelength is reflected and diffracted by a flat monochromator, and the single wavelength of the single wavelength with the mirror image of the light source having the flat monochromator as a mirror surface is the center of divergence. The total reflection X-ray analysis method according to claim 1, wherein the divergent X-ray beam composed of X-rays is formed.
  6. A predetermined single-wavelength X-ray is dispersed from an incident X-ray beam having a continuous wavelength and condensed to a linear or point-like focal point to form a divergent X-ray beam composed of the X-rays diverging from the focal point. A divergent X-ray beamformer,
    The sample holding the position and the viewing angle of the sample with respect to the diverging X-ray beam so that the part of the X-ray constituting the diverging X-ray beam is incident on the sample surface at a critical angle of total reflection. A holding stand,
    A position sensitive detector that measures the intensity of fluorescent X-rays or photoelectrons emitted from each of a plurality of areas set on the sample surface, or the intensity of reflected X-rays reflected from each of the areas;
    A viewing angle of the X-rays incident on each region is calculated for each region, and an intensity distribution in the depth direction of the X-rays entering the sample from the calculated viewing angle is calculated for each of the regions. An intrusion X-ray intensity calculation unit that calculates for each region;
    The X-ray absorption fine structure (XAFS) sample depth direction based on the intensity distribution calculated for each region and the intensity measured for each region for a plurality of the single wavelengths A total reflection X-ray analysis apparatus comprising: an XAFS detection unit that calculates a distribution.
JP2012008497A 2012-01-18 2012-01-18 Total reflection x-ray analysis method and total reflection x-ray analysis device Pending JP2013148431A (en)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04106463A (en) * 1990-08-27 1992-04-08 Rigaku Denki Kogyo Kk Total reflection fluorescence x-ray analysis
JPH05196583A (en) * 1992-01-23 1993-08-06 Hitachi Ltd Total reflection x-ray analyzer
JPH08184572A (en) * 1995-01-04 1996-07-16 Hitachi Ltd Total-reflection x-ray analytical apparatus
JP2004093521A (en) * 2002-09-04 2004-03-25 Fujitsu Ltd Apparatus and method for x-ray reflectance measuring
JP2004333131A (en) * 2003-04-30 2004-11-25 Rigaku Corp Total reflection fluorescence xafs measuring apparatus
JP2010038627A (en) * 2008-08-01 2010-02-18 Hitachi Ltd X-ray imaging device and x-ray imaging method

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04106463A (en) * 1990-08-27 1992-04-08 Rigaku Denki Kogyo Kk Total reflection fluorescence x-ray analysis
JPH05196583A (en) * 1992-01-23 1993-08-06 Hitachi Ltd Total reflection x-ray analyzer
JPH08184572A (en) * 1995-01-04 1996-07-16 Hitachi Ltd Total-reflection x-ray analytical apparatus
JP2004093521A (en) * 2002-09-04 2004-03-25 Fujitsu Ltd Apparatus and method for x-ray reflectance measuring
JP2004333131A (en) * 2003-04-30 2004-11-25 Rigaku Corp Total reflection fluorescence xafs measuring apparatus
JP2010038627A (en) * 2008-08-01 2010-02-18 Hitachi Ltd X-ray imaging device and x-ray imaging method

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