JP6303553B2 - X-ray analysis method and X-ray analysis apparatus - Google Patents

Description

  The present invention relates to an X-ray analysis method and an X-ray analysis apparatus using an electron yield XAFS (X-ray Absorption Fine Structure) method.

  Compound semiconductors are industrially used in electronic devices such as high-frequency devices and optical devices such as light-emitting diodes and laser diodes. High frequency devices include HEMT (High Electron Mobility Transistor), HBT (Heterojunction Bipolar Transistor), MMIC (Microwave Monolithic IC) for mobile phones, and the like. Examples of the light emitting diode include LED lighting, a remote controller, and a liquid crystal backlight. Laser diodes include optical communication devices and optical pickups (DVD, CD).

  In such a compound semiconductor device, a high-quality crystalline sample such as gallium arsenide (GaAs), gallium phosphide (GaP), indium phosphide (InP), gallium nitride (GaN), or the like is used. For example, in a HEMT device composed of a barrier layer / channel layer, a two-dimensional electron gas is generated at the interface of the compound semiconductor layer, and electrons move on the channel layer side of the interface. Therefore, a high quality epitaxial crystal is required for the channel layer. It has been.

  Here, the high-quality crystal means a state in which there is no atomic vacancy and the crystal arrangement is not disturbed. In such local structure analysis, the XAFS method is an effective analysis method. The XAFS method irradiates a sample with X-rays and analyzes the spectrum obtained by obtaining the X-ray energy dependency of the X-ray intensity before and after transmission through the sample. How to get. In the sample on the substrate, X-rays cannot pass through the sample. Therefore, in general, instead of measuring the transmitted light intensity, a fluorescent XAFS method, which is a method for measuring the intensity of fluorescent X-rays generated from a sample, and an electron yield XAFS method, which is a method for measuring the intensity of Auger electrons, are used. It is done. A compound semiconductor sample is composed of a large number of epitaxial films having a similar structure, and the film thickness is often 1 μm or more. In the XAFS analysis of such a film structure, it is known that when the fluorescent XAFS method is used, the self-absorption effect increases according to the penetration depth of the X-ray, and as a result, the spectrum is distorted. In contrast, in the electron yield XAFS method, the spectrum obtained is limited to about 100 nm, which is the escape depth of Auger electrons, regardless of the film thickness of the analysis sample. Therefore, there is almost no self-absorption effect, and this is a suitable method for XAFS analysis of compound semiconductor devices.

  As a conventional technique of the electron yield XAFS method, there is a technique of Patent Document 1. Patent Document 1 discloses an apparatus and method for keeping a background component due to scattered electrons and secondary electrons, which increase with an increase in the energy of irradiated X-rays, at a constant value, facilitating the removal thereof, and extracting only a signal component with high accuracy. Has been. As an embodiment of the electron yield XAFS method, there is a conversion electron yield XAFS method. The conversion electron yield XAFS method is a method of irradiating a sample with X-rays, and electrons ejected from the sample ionize the surrounding gas (He gas, etc.) and measure the energy dependence of the X-rays for the current flowing as a result. It is. This technique is often used because it does not require a vacuum around the sample. As a conventional technique of the conversion electron yield XAFS method, there is a technique of Patent Document 2. Patent Document 2 discloses an apparatus and method for reducing a background current by forming a peripheral wall of an analysis chamber with a conductor and grounding it, and lining it with an insulator made of only an element lighter than argon.

JP 2001-221756 A JP 2000-11503 A JP-A-4-315448

However, the XAFS analysis of a crystalline sample such as a compound semiconductor device has the following problems.
That is, when an X-ray energy dependent spectrum is obtained, as a result of scanning the X-ray energy, the Bragg condition may be satisfied in any X-ray energy during spectrum acquisition. In this case, there is a problem that a correct spectrum cannot be obtained due to the influence of interference diffraction lines generated by satisfying the Bragg condition. This problem cannot be solved even if the techniques of Patent Documents 1 and 2 are used.

  The present invention has been made to solve the above-mentioned problems, and for a crystalline sample such as a compound semiconductor device, a regular X-ray energy-dependent spectrum without the influence of disturbing diffraction lines can be easily and reliably obtained. It is an object of the present invention to provide an X-ray analysis method and an X-ray analysis apparatus that can be obtained automatically regardless of human hands and that can obtain highly reliable information with high reliability on a local structure.

One aspect of the X-ray analysis method is an X-ray analysis method using an electron yield XAFS method, in which a sample is irradiated with X-rays, and electrons emitted from the sample or the electrons ionize a surrounding gas. In obtaining the X-ray energy dependence of the flowing current, the orientation of the sample with respect to the irradiated X-ray is changed, and the X-ray energy dependence spectrum is obtained in at least three different crystal orientations. determining the spectrum becomes the same in the two said spectral among the spectrum of species as legitimate.
One aspect of the X-ray analysis method is an X-ray analysis method using an electron yield XAFS method, in which a sample is irradiated with X-rays, and electrons emitted from the sample or the electrons ionize a surrounding gas. When obtaining the X-ray energy dependence of the flowing current, the orientation of the sample with respect to the X-rays irradiated by rotating the sample around the central axis of the sample table on which the sample is placed is swung. The X-ray energy dependency is acquired while changing.

One aspect of the X-ray analyzer includes an X-ray source that generates X-rays, a sample stage on which a sample to be irradiated with X-rays is placed, and the sample stage on the center axis of the sample stage within the sample plane A drive mechanism that rotates around, an electrode that faces the sample stage and is capable of applying a predetermined voltage between the sample stage, and controls the voltage of the X-ray source, the drive mechanism, and the electrode; and a control unit for acquiring the X-ray energy dependence of current flowing by electrons jumped out from the sample, or the electrons ionize the surrounding gas, the drive mechanism, the sample to X-rays to be irradiated The rotation angle of the sample stage is changed so that there are at least three different crystal orientations .
One aspect of the X-ray analyzer includes an X-ray source that generates X-rays, a sample stage on which a sample to be irradiated with X-rays is placed, and the sample stage on the center axis of the sample stage within the sample plane A drive mechanism that rotates around, an electrode that faces the sample stage and is capable of applying a predetermined voltage between the sample stage, and controls the voltage of the X-ray source, the drive mechanism, and the electrode; A control unit that acquires the X-ray energy dependence of the electrons that have jumped out of the sample, or the current that flows when the electrons ionize the surrounding gas, and the drive mechanism moves the sample stage within the sample plane. Rotate and swing around the center axis of the sample stage.

  According to the above aspects, a normal X-ray energy-dependent spectrum that is free from the influence of interfering diffraction lines can be easily and reliably obtained automatically without relying on human hands for a crystalline sample such as a compound semiconductor device. It is possible to obtain highly reliable information with high reliability on the local structure.

It is a flowchart of the X-ray-analysis method using the electron yield XAFS method of the comparative example. It is a characteristic view which shows the X-ray analysis in a comparative example. It is a schematic diagram which shows schematic structure of the X-ray analyzer by 1st Embodiment. It is a flowchart which shows the X-ray-analysis method by 1st Embodiment in order of a step. It is a characteristic view which shows the X-ray analysis in 1st Embodiment. It is a characteristic view which shows the X-ray analysis in 1st Embodiment. It is a characteristic view which shows the X-ray analysis in 1st Embodiment. It is a flowchart which shows the X-ray-analysis method by 2nd Embodiment in order of a step. It is a schematic diagram which shows the result of having compared the footprint in the case of measuring by the free rotation of a sample, and the rotation rocking | fluctuation of the sample which limited the swing width. It is a schematic diagram which shows the result of having compared the footprint in the case of measuring by the free rotation of a sample, and the rotation rocking | fluctuation of the sample which limited the swing width. In a 2nd embodiment, it is a characteristic figure for explaining the optimal swing width in rotation swing. It is a characteristic view which shows the X-ray analysis in 2nd Embodiment.

  Hereinafter, embodiments of an X-ray analysis method and an X-ray analysis apparatus will be described in detail with reference to the drawings. As a sample for X-ray analysis, a compound semiconductor having a laminated structure of GaN (film thickness 2 μm) / AlN film thickness (30 nm) / SiC substrate from the upper layer was used as a sample for analysis.

Prior to describing the present embodiment, a conventional technique will be described as a comparative example of the present embodiment.
FIG. 1 is a flowchart of an X-ray analysis method using an electron yield XAFS method of a comparative example.
In the comparative example, first, data of the X-ray intensities I ₀ and I ₁ are acquired while changing the energy of the monochromatic X-ray (step S1). Here, the incident angle of monochromatic X-rays on the sample is 10 °.

Subsequently, I ₁ / I ₀ (E) is calculated from the acquired energy dependency data of I ₀ and I ₁ (step S2).
This energy dependence data corresponds to the measured spectrum shown in FIG.

Subsequently, the background is removed from the spectrum of I ₁ / I ₀ (E), and XAFS vibration is derived (step S3).
The background is removed by the following two-step method. In the first stage, the background is removed using a so-called Victoreen's empirical formula (Aλ ³ + Bλ ⁴ + C) or the like. Here, λ is the wavelength of monochromatic X-ray, and A, B, and C are constants. When the spectrum of I ₁ / I ₀ (E) is _expressed as μ _t (E) and the spectrum obtained by Victoreen's empirical formula is expressed as μ _v (E), in the first stage, μ (E) = μ _t (E) −μ _v (E) is obtained. In the second stage, χ (E) = (μ (E) −μ ₀ (E)) / μ ₀ (E) is obtained. Here, μ ₀ (E) is an absorption coefficient by an isolated atom having no EXAFS signal, and can be obtained by a so-called cubic spline method or the like. With respect to χ (E) thus determined, a spectrum derived by multiplying k ² by converting energy E into wave number k and further enhancing XAFS oscillation in the high-k region is shown in FIG. This corresponds to the XAFS vibration shown in FIG.

Subsequently, based on the XAFS vibration spectrum, the analyst determines the presence or absence of the interference diffraction line from the spectrum, and removes the interference diffraction line (step S4).
Subsequently, a radial distribution is obtained by Fourier transforming the spectrum of the XAFS vibration from which the interference diffraction lines are removed (step S5).
In the measurement by this comparative example, since data was acquired with energy near the K absorption edge of Ga, a local structure near the Ga atom can be obtained.

  In the spectrum of the XAFS vibration of FIG. 2B, what is clearly determined as an interference diffraction line is observed. Since this interference diffraction line is observed no matter how many times the same measurement is performed, it is different from electrical noise that changes from measurement to measurement. In FIG. 2 (b), in addition to what is clearly determined as an interference diffraction line, there are many cases where it is difficult to determine whether it is a normal (true) XAFS vibration or an interference diffraction line. . In the comparative example, there is an analyst's discretion in determining and removing the interference diffraction lines, and the reliability of the measurement results is impaired.

(First embodiment)
First, the first embodiment will be described. FIG. 3 is a schematic diagram showing a schematic configuration of the X-ray analyzer according to the first embodiment.

[Configuration of X-ray analyzer]
This X-ray analyzer includes an irradiation X-ray intensity monitor detector 2, high voltage power supplies 6 and 19, current amplifiers 7 and 22, V / F converters 8 and 23, scalers 9 and 24, control / analysis computer 10, electronic A detector 13 for yield measurement is provided.

  White X-rays (not shown) having a continuous energy distribution emitted from an X-ray source (not shown) are separated by a monochromator (not shown). For the monochromatic device, for example, germanium (Ge) crystal, silicon (Si) crystal or the like can be used.

  The irradiation X-ray intensity monitor detector 2 includes an irradiation X-ray intensity detector entrance window 3, an irradiation X-ray intensity detector exit window 4, and a pair of irradiation X-ray intensity detector electrodes 5a and 5b. Further, the irradiation X-ray intensity monitor detector 2 includes an irradiation X-ray intensity detector gas inlet 11 and an irradiation X-ray intensity detector gas outlet 12. As a gas introduced into the detector 2 for irradiation X-ray intensity monitor, a gas that transmits about 80% to about 90% of X-rays is selected. As the gas, for example, nitrogen (N), helium (He), argon (Ar), or a mixed gas thereof is used.

The high-voltage power supply 6 applies a voltage of, for example, about 1000 V between the irradiation X-ray intensity detector electrodes 5a and 5b.
The current amplifier 7 amplifies the current that flows when the monochromatic X-ray 1 passes through the irradiation X-ray intensity monitor detector 2 and converts it into a voltage.
The V / F converter 8 converts the above voltage into a pulse train.
The scaler 9 counts the above pulse train. The counting result is stored in the control / analysis computer 10 as I ₀ .

  The electron yield measuring detector 13 includes a conductive sample stage 16 on which the analysis analysis sample 17 having the layer structure described above is placed, and an electron yield detector electrode 18 facing the conductive sample stage 16. Further, the electron yield measuring detector 13 includes an irradiation X-ray intensity detector gas inlet 20 and an irradiation X-ray intensity detector gas outlet 21. For example, helium (He) gas is used as the gas introduced into the electron yield measuring detector 13.

For example, as shown by an arrow A, the conductive sample table 16 can freely change the rotation angle of the conductive sample table 16 or rotate and swing the conductive sample table 16 at a predetermined angle set at high speed. A rotation mechanism 15 is provided.
The high voltage power source 19 applies a voltage of about 1000 V between the conductive sample stage 16 and the electron yield detector electrode 18.

The current amplifier 22 amplifies the current that flows when the monochrome X-ray 1 irradiates the analysis sample 17 and converts it into a voltage.
The V / F converter 23 converts the above voltage into a pulse train.
The scaler 24 counts the above pulse train. The counting result is stored in the control / analysis computer 10 as I ₁ .

The control / analysis computer 10 irradiates white X-rays from an X-ray source, introduces and discharges gas to the irradiated X-ray intensity monitor detector 2 and electron yield measuring detector 13, and the voltages of the high-voltage power supplies 6 and 19. Driving and controlling the rotation of the rotation angle or rotation by the application and rotation mechanism 15 is controlled. Further, the control / analysis computer 10 stores I ₀ and I ₁ which are the counting results of the scalers 9 and 24 and calculates the spectrum of I ₁ / I ₀ (E), derivation of XAFS vibration, Fourier transform and the like, which will be described later. Perform various calculations and analysis.

This X-ray analyzer is used as follows.
The spectrally monochromatic X-ray 1 enters the irradiation X-ray intensity monitor detector 2 from the irradiation X-ray intensity detector incident window 3, and detects the irradiation X-ray intensity monitor detection from the irradiation X-ray intensity detector emission window 4. The light is emitted out of the vessel 2. The monochromatic X-ray 1 passes between the irradiation X-ray intensity detector electrodes 5 a and 5 b to which a voltage of about 1000 V is applied by the high-voltage power supply 6.

The current that flows when the monochromatic X-ray 1 passes through the irradiation X-ray intensity monitor detector 2 is amplified by the current amplifier 7 and converted into a voltage, then converted into a pulse train by the V / F converter 8 and counted by the scaler 9. Is done. The counting result is stored in the control / analysis computer 10 as I ₀ .

  The monochromatic X-ray 1 transmitted through the irradiation X-ray intensity monitor detector 2 enters the electron yield measuring detector 13 through the electron yield detector incident window 14 and is placed on the conductive sample stage 16. The sample 17 is irradiated. The conductive sample stage 16 is rotationally driven by the rotation mechanism 15 while the analysis sample 17 is fixed. A voltage of about 1000 V is applied between the conductive sample stage 16 and the electron yield detector electrode 18 by a high voltage power source 19.

When the inside of the electron yield measuring detector 13 is evacuated, the electrons that have jumped out of the analysis sample 17 due to the irradiation of the monochromatic X-ray 1 are attracted to the positive electrode side. When the inside of the electron yield measuring detector 13 is filled with gas, the emitted electrons ionize these gases. The gas is introduced through the electron yield detector gas inlet 20 and discharged from the electron yield detector gas outlet 21. When the introduced gas is, for example, He, ionized He ⁺ is attracted to the negative electrode side.

Thus, the current that flows when the analysis sample 17 is irradiated with the monochromatic X-ray 1 is amplified by the current amplifier 22 and converted into a voltage, and then converted into a pulse train by the V / F converter 23, and by the scaler 24. Counted. The counting result is stored in the control / analysis computer 10 as I ₁ .

[X-ray analysis method]
An X-ray analysis method using the X-ray analyzer configured as described above will be described.
FIG. 4 is a flowchart showing the X-ray analysis method according to the first embodiment in the order of steps.

First, the control / analysis computer 10 changes the energy of the monochromatic X-ray 1 while changing I _0.
And it acquires each data energy dependence of I ₁ (step S11).
The angle δ of the crystal orientation of the analysis sample 17 with respect to the monochromatic X-ray 1 is set to 0 ° in the initial state. The incident angle of the monochromatic X-ray 1 on the analysis sample 17 is set to 10 °, for example.

Subsequently, the control / analysis computer 10 calculates a spectrum of I ₁ / I ₀ (E) from the acquired energy dependency data of I ₀ and I ₁ (step S12).
The calculated spectrum of I ₁ / I ₀ (E) is shown in FIG. In FIG. 5A, at least one clear interference diffraction line (a portion surrounded by a broken-line circle) is observed. FIG. 5B shows a state in which the rectangle A in FIG. 5A, which is the vicinity of the interference diffraction line, is enlarged in the direction of the wave number k. The dependence of I ₀ and I ₁ on the rotation φ in the sample surface is obtained from the energy of the interference diffraction lines, and I ₁ / I ₀ (φ) is derived. The derived profile showed a peak, and the half width was about 0.05 ° (not shown). This measurement of the rotation φ dependency is for estimating the rotation angle of the analysis sample 17 described later, and in the case of a similar analysis sample, it is usually not necessary to execute it again.

Subsequently, the control / analysis computer 10 drives the rotation mechanism 15 to rotate (rotate) the analysis sample 17 on the conductive sample stage 16 to change the angle of the analysis sample 17 with respect to the monochromatic X-ray 1. (Step S13).
Here, the angle δ of the analysis sample 17 with respect to the monochromatic X-ray 1 is changed from 0 ° in the initial state to, for example, 0.1 °.

Subsequently, the control / analysis computer 10 sequentially executes Steps S14 and S15 similar to Steps S11 and S12 with the angle δ set to 0.1 °. That is, the control and analysis computer 10 acquires the data of the energy dependence of I ₀ and I ₁ (step S14), I ₀ and I ₁ of the energy dependence of I ₁ / I ₀ from the data of (E ) Is calculated (step S15).

Subsequently, the control / analysis computer 10 drives the rotation mechanism 15 to rotate (rotate) the analysis sample 17 on the conductive sample stage 16 to change the angle of the analysis sample 17 with respect to the monochromatic X-ray 1. (Step S16).
Here, the angle δ of the analysis sample 17 with respect to the monochromatic X-ray 1 is changed from 0.1 ° to, for example, −0.1 °.

Subsequently, the control / analysis computer 10 sequentially executes Steps S17 and S18 similar to Steps S11 and S12 in a state where the angle δ is set to −0.1 °. That is, the control and analysis computer 10 acquires the data of the energy dependence of I ₀ and I ₁ (step S17), I ₀ and I ₁ of the energy dependence of I ₁ / I ₀ from the data of (E ) Is calculated (step S18).

The spectra of the three types of I ₁ / I ₀ (E) obtained in steps S12, 15, and 18 are shown in FIG. Each spectrum is represented by a broken line, a one-dot chain line, and a two-dot chain line. In FIG. 6A, three types of spectra of I ₁ / I ₀ (E) having different angles δ are shown together. FIG. 6B shows a state in which the rectangle A in FIG. 6A is enlarged in the direction of the wave number k. Except for the three interfering diffraction lines a, b and c, the three I ₁ / I ₀ (E) spectra overlap.

This result means that in this embodiment, the peak observed in the region other than the three interference diffraction lines a, b, and c is not the interference diffraction line but a normal (true) XAFS oscillation. ing. The spectrum of regular I ₁ / I ₀ (E) is shown by a solid line in FIG. FIG. 7B shows a state in which the rectangle A in FIG. 7A is enlarged in the direction of wave number k.

In subsequent step S18 step S19, the control and analysis computer 10, based on the spectrum of the three _{I 1 / I 0 (E)} , selects the spectrum of normal _{I 1 / I 0 (E)} .

The reason why three different I ₁ / I ₀ (E) spectra are acquired will be described.
When it is easy to determine whether or not the interference diffraction lines are correct as in this embodiment, it is sufficient to acquire two types of I ₁ / I ₀ (E) spectra. However, when the XAFS vibration peak position and the interference diffraction line overlap, it may be difficult to determine which is the correct XAFS spectrum in the two types of spectrum measurement. Even in such a case, by performing three types of spectrum measurement, it is possible to determine that two of the three types of spectra are normal spectra and to eliminate the discretion of the analyst. It becomes possible.

Subsequently, the control / analysis computer 10 removes the background from the spectrum of the regular I ₁ / I ₀ (E) selected in step S19, as in step S3 of FIG. Derived (step S20).
Subsequently, the control / analysis computer 10 obtains a radial distribution by performing Fourier transform on the derived XAFS vibration spectrum (step S21).

  As described above, according to the present embodiment, for a crystalline sample such as a compound semiconductor device, a normal X-ray energy-dependent spectrum without the influence of disturbing diffraction lines is obtained as shown in step S4 of FIG. It is possible to easily and surely obtain it automatically without manual intervention, and to obtain highly reliable and highly accurate information about the local structure.

(Second Embodiment)
Next, a second embodiment will be described.
In the present embodiment, as in the first embodiment, an X-ray analysis method using the X-ray analyzer of FIG. 3 is disclosed. FIG. 8 is a flowchart showing the X-ray analysis method according to the second embodiment in the order of steps.

  First, the control / analysis computer 10 drives the rotation mechanism 15 to rotate and swing the analysis sample 17 on the conductive sample stage 16 (step S31).

The reason why the analysis sample 17 is not freely rotated but rotated in step S31 will be described.
FIG. 9 and FIG. 10 are schematic diagrams showing the results of comparing the footprints (regions where X-rays irradiate the sample) when measured by the free rotation of the sample and the rotational swing of the sample with a limited swing width. .

  9A shows a footprint when the X-ray beam size is 0.5 mm × 0.5 mm, the incident angle is 10 °, and there is no oscillation. (B) shows the footprint when the beam size is 0.5 mm × 0.5 mm, the incident angle is 10 °, and the rotational oscillation is ± 3 °. (C) shows a footprint in the case of a beam size of 0.5 mm × 0.5 mm, an incident angle of 10 °, and free rotation.

  10A shows a footprint when the beam size is 0.1 mm × 0.5 mm, the incident angle is 0.12 °, and there is no oscillation. (B) shows a footprint when the beam size is 0.1 mm × 0.5 mm, the incident angle is 0.12 °, and the rotation is ± 3 °. (C) shows a footprint in the case of a beam size of 0.1 mm × 0.5 mm, an incident angle of 0.12 °, and free rotation.

  In the case of free rotation, the footprint increases. In particular, when it is desired to perform measurement in the vicinity of the surface under the total reflection condition as shown in FIG. In the electron yield XAFS method, when the monochromatic X-ray 1 directly irradiates the conductive sample stage 16, noise is generated. Therefore, in order to prevent the generation of noise, it is necessary to increase the size of the analysis sample 17 beyond the footprint.

  In the case of the rotational swing as shown in FIG. 10B, the size of the analysis sample 17 may be about 50 mm × 5 mm. On the other hand, in the case of free rotation as shown in FIG. 10C, the size of the analysis sample 17 needs to be about 50 mm × 50 mm. Usually, the size of the conductive sample stage used in the electron yield XAFS method is about 50 mmφ. 10B, the size of the analysis sample 17 is sufficiently smaller than that of the conductive sample stage 16. On the other hand, in the case of free rotation in FIG. 10C, the sizes of the conductive sample stage 16 and the analysis sample 17 are substantially equal. In the electron yield XAFS method, it is necessary to make the size of the analysis sample 17 sufficiently smaller than that of the conductive sample stage 16, so the results shown in FIG. 9 and FIG. Shows that it will be difficult.

Next, the optimum swing width in the rotational swing will be described.
FIG. 11A shows the result of rocking with various swing widths. FIG. 11B shows a state in which the inside of the rectangle A in FIG. 11A is enlarged in the direction of the wave number k. It can be confirmed that the interference diffraction lines are removed by rotating and swinging with a swing width of ± 3 ° or more. As a result of examining a plurality of samples having different crystal states, it was confirmed that a swing width of about 100 times the half width of the spectrum of I ₁ / I ₀ (φ) was suitable. Similarly, when the speed of rotation was also investigated, it was generally good under the condition of 1 reciprocation to 10 reciprocations per measurement point, and particularly good under conditions of 5 reciprocation to 10 reciprocations per measurement point. It was confirmed that a result was obtained. In the case of less than one reciprocation per measurement point, the interference diffraction lines were often not removed. On the other hand, even when the number of reciprocations was 10 or more per measurement point, no further improvement in the interference diffraction line removal effect was observed. From the viewpoint of fixing the analysis sample 17 to the conductive sample stage 16 (displacement of the analysis sample), it is not necessary to make it 10 or more reciprocations. In the present embodiment, based on the above results, it has been found that it is preferable to rotate and swing the range of ± 3 ° at a speed of 10 reciprocations per measurement point.

Subsequently, the control / analysis computer 10 changes the energy of the monochromatic X-ray 1 while rotating and swinging the analysis sample 17 on the conductive sample stage 16 within a range of ± 3 °, and the energy of I ₀ and I ₁ . Each data of dependency is acquired (step S32).
The incident angle of the monochromatic X-ray 1 on the analysis sample 17 is set to 10 °, for example.

Subsequently, the control / analysis computer 10 calculates the spectrum of I ₁ / I ₀ (E) from the acquired energy dependency data of I ₀ and I ₁ (step S33).
Subsequently, the control / analysis computer 10 removes the background from the spectrum of I ₁ / I ₀ (E) acquired in step S33 and derives the XAFS vibration in the same manner as in step S3 of FIG. 1 of the comparative example. (Step S34).
Subsequently, the control / analysis computer 10 obtains a radial distribution by performing Fourier transform on the derived XAFS vibration spectrum (step S35).

The spectrum of more than I ₁ / I ₀ obtained as the (E), the result of comparison of the spectra of the first embodiment I obtained in Comparative Example described in Embodiment ₁ / I ₀ (E) As shown in FIG. In FIG. 12, the spectrum of I ₁ / I ₀ (E) obtained by the present embodiment is indicated by a broken line, and the spectrum of I ₁ / I ₀ (E) obtained by a comparative example is indicated by a one-dot chain line. It can be confirmed that the interference diffraction lines have been removed by measuring in the rotating and swinging state. This result shows that the discretion of the analyst can be eliminated by removing the interference diffraction lines, unlike the comparative example.

  As described above, according to the present embodiment, for a crystalline sample such as a compound semiconductor device, a normal X-ray energy-dependent spectrum without the influence of disturbing diffraction lines is obtained as shown in step S4 of FIG. It is possible to easily and surely obtain it automatically without manual intervention, and to obtain highly reliable and highly accurate information about the local structure.

(Other embodiments)
The functions of the control / analysis computer 10 of the X-ray analysis apparatus of FIG. 3 according to the above-described embodiments can be realized by operating a control program stored in an auxiliary storage device of a computer (CPU) or the like. Similarly, procedures such as steps S11 to S21 in FIG. 4 and steps S31 to S35 in FIG. 8 can be realized by operating a control program. This control program and a computer-readable storage medium storing the control program are included in this embodiment.

  Specifically, the control program is recorded on a recording medium such as a CD-ROM or provided to a computer via various transmission media. As a recording medium for recording the control program, a flexible disk, a hard disk, a magnetic tape, a magneto-optical disk, a nonvolatile memory card, or the like can be used in addition to the CD-ROM. On the other hand, as a transmission medium for the control program, a communication medium in a computer network system for propagating and supplying program information as a carrier wave can be used. Here, the computer network is a WAN such as a LAN or the Internet, a wireless communication network, or the like, and the communication medium is a wired line such as an optical fiber or a wireless line.

  Further, the control program included in the present embodiment is not limited to that in which the functions of the above-described embodiments are realized by the computer executing the supplied control program. For example, even when the control program is implemented in cooperation with an OS (operating system) running on a computer or other application software, the control program is implemented in this embodiment. include. In addition, even when all or part of the processing of the supplied control program is performed by the function expansion board or function expansion unit of the computer and the functions of the above-described embodiment are realized, the control program is implemented in this embodiment Included in the form.

  Hereinafter, various embodiments of the X-ray analysis method and the X-ray analysis apparatus will be collectively described as supplementary notes.

(Appendix 1) An X-ray analysis method using an electron yield XAFS method,
When obtaining the X-ray energy dependence of the electrons flowing out from the sample by irradiating the sample or the current flowing when the electrons ionize the surrounding gas, the direction of the sample is changed with respect to the irradiated X-ray. And obtaining the X-ray energy dependency.

  (Supplementary Note 2) The X-ray energy-dependent spectrum is acquired in at least three different crystal orientations, and the spectrum that is the same in two of the acquired three types of spectrum is determined as a normal one. The X-ray analysis method according to appendix 1, wherein:

  (Supplementary note 3) The X-ray analysis method according to supplementary note 1, wherein the X-ray energy dependency is acquired while rotating and swinging the sample.

  (Supplementary note 4) The X-ray analysis method according to supplementary note 3, wherein an angle of the rotational oscillation is greater than ± 1 ° and within ± 30 °.

(Supplementary Note 5) X-ray source for generating X-rays;
A sample stage on which a sample to be irradiated with X-rays is placed;
A drive mechanism for rotationally driving the sample stage;
An electrode facing the sample stage and capable of applying a predetermined voltage between the sample stage;
A control unit that controls the voltages of the X-ray source, the drive mechanism, and the electrode, and acquires the X-ray energy dependency of electrons that have jumped out of the sample or current that flows when the electrons ionize the surrounding gas. X-ray analyzer characterized by including.

  (Additional remark 6) The said drive mechanism changes the rotation angle of the said sample stand so that the said sample may become at least 3 different crystal orientation with respect to the X-ray irradiated, The additional remark 5 characterized by the above-mentioned. X-ray analyzer.

  (Supplementary note 7) The X-ray analyzer according to supplementary note 5, wherein the drive mechanism rotates and swings the sample stage.

  (Supplementary note 8) The X-ray analysis apparatus according to supplementary note 5, wherein an angle of the rotational oscillation is greater than ± 1 ° and within ± 30 °.

DESCRIPTION OF SYMBOLS 1 Monochromatic X-ray 2 Irradiation X-ray intensity monitor detector 3 Irradiation X-ray intensity detector entrance window 4 Irradiation X-ray intensity detector exit window 5a Irradiation X-ray intensity detector electrode 5b Irradiation X-ray intensity detector electrodes 6 and 19 High voltage power supply 7, 22 Current amplifier 8, 23 V / F converter 9, 24 Scaler 10 Control / analysis computer 11 Irradiation X-ray intensity detector gas inlet 12 Irradiation X-ray intensity detector gas outlet 13 Detection for electron yield measurement 14 Electron yield detector entrance window 15 Rotating mechanism 16 Conductive sample base 17 Analytical sample 18 Electron yield detector electrode 20 Electron yield detector gas inlet 21 Electron yield detector gas outlet

Claims (4)

An X-ray analysis method using an electron yield XAFS method,
When obtaining the X-ray energy dependence of the electrons flowing out from the sample by irradiating the sample or the current flowing when the electrons ionize the surrounding gas, the direction of the sample is changed with respect to the irradiated X-ray. Thus, the X-ray energy-dependent spectrum is acquired in at least three different crystal orientations, and the spectrum that is the same in two of the acquired three types of spectrum is determined as a normal one. An X-ray analysis method characterized by the above. An X-ray analysis method using an electron yield XAFS method,
When the sample is irradiated with X-rays to acquire the X-ray energy dependence of the electrons that have jumped out of the sample or the current that flows when the electrons ionize the surrounding gas, the sample is mounted within the sample plane. An X-ray analysis method characterized in that the X-ray energy dependency is acquired while changing the orientation of the sample with respect to X-rays to be irradiated while rotating around a central axis of a sample stage placed . An X-ray source generating X-rays;
A sample stage on which a sample to be irradiated with X-rays is placed;
A drive mechanism for rotating the sample stage around the central axis of the sample stage in the sample plane;
An electrode facing the sample stage and capable of applying a predetermined voltage between the sample stage;
A control unit that controls the voltages of the X-ray source, the drive mechanism, and the electrode, and acquires the X-ray energy dependence of the electrons that have jumped out of the sample or the current that flows when the electrons ionize the surrounding gas;
Including
The X-ray analysis apparatus characterized in that the drive mechanism changes the rotation angle of the sample stage so that the sample has at least three different crystal orientations with respect to the irradiated X-rays. An X-ray source generating X-rays;
A sample stage on which a sample to be irradiated with X-rays is placed;
A drive mechanism for rotating the sample stage around the central axis of the sample stage in the sample plane;
An electrode facing the sample stage and capable of applying a predetermined voltage between the sample stage;
A control unit that controls the voltages of the X-ray source, the drive mechanism, and the electrode, and acquires the X-ray energy dependence of the electrons that have jumped out of the sample or the current that flows when the electrons ionize the surrounding gas;
Including
The X-ray analysis apparatus characterized in that the drive mechanism rotates and swings the sample stage around the central axis of the sample stage within the sample plane .

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