JPH0361840A - Measuring apparatus for x-ray absorption spectrum - Google Patents

Abstract

PURPOSE:To prevent the expansion of X rays due to diffusion, to make it possible to bring an X-ray generator and a sample close together and to improve analyzing accuracy by utilizing an X-ray source formed by excitation with an electron beam, and arranging an electron-beam generating part, the X-ray source, the sample, an X-ray spectral crystal and a detector in the same vacuum body. CONSTITUTION:An electron beam 8 generated from an electron gun 7 is narrowed to a small diameter of several mum or less through an electromagnetic lens which is not shown. The electron beam is projected on an X-ray generating target 9. Thus, X-rays 10 are generated in the target 9 and projected on a sample 6 through an electron-beam shielding filter 12. The filter 12 is the filter which prevents the input of higher energy electrons reflected from the surface of the target 9 into an X-ray detector 17. The filter is provided between the sample 6 and an X-ray spectral crystal 14 and the like. The X-rays 10 projected on the sample 6 undergoes specific absorption of the sample 6. The X-rays 10 are transmitted through the sample 6 and inputted into the crystal 14. In the crystal 14, the X-rays are diffracted under the Bragg diffraction condition of nlambda=2d.sintheta and undergo spectroscopy. Then, the X rays are inputted into an X-ray detector 17 through a slit 16, and the intensity is measured with an X-ray measuring circuit 18.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention uses X-rays to
Tend-ed X-ray Absorption
Fine 5structure), XANE
S (X-ray Absorption Near
The present invention relates to an X-ray absorption spectrum measurement device for analyzing X-ray absorption spectroscopy (Edge 5 structure), etc., and particularly to a device using an X-ray source using electron beam excitation.

[Prior Art] X-ray diffraction has been widely used as a method for analyzing the structure of substances using X-rays. This X-ray diffraction method utilizes the diffraction phenomenon of X-rays according to atomic arrangement.
Therefore, there is a drawback that the measurement target is limited to crystalline substances.

In contrast, in recent years, a method of measuring X-ray absorption spectra has been used as a method for analyzing the structure of substances.

The method for measuring this X-ray absorption spectrum is as follows: (1) A Kossel structure that appears within a range of several tens of eV from the energy value of the X-ray absorption edge of the substance [hereinafter referred to as XA
NES (X-ray Absorption
NearEdge 5 structure) is used to analyze the state of matter mainly from subtle spectral differences at absorption edge positions.

■1000e on the higher energy side from the X-ray absorption edge of the substance
X-ray absorption continuous fine structure appearing within the range up to V [hereinafter referred to as
ExtendedX-r
ay Absorption Fine 5truct
A method for analyzing the state and structure of substances by investigating the

It is roughly divided into two types.

The X-ray absorption spectrum measurement method is based on the excitation phenomenon between the atoms of the substance and the X-rays, and is related to energy absorption of X-rays. Therefore, it is not limited to crystalline materials, but can be used to measure non-crystalline materials. In particular, EXAFS analysis has been proven to be able to analyze electronic states and structures in solids such as crystalline and non-crystalline metal alloys, insulators, and semiconductors.

As a conventional apparatus for performing analysis such as EXAFS and XANES as described above, there is one shown in FIG. 7th
The figure shows the outline of the configuration of a conventional X-ray absorption spectrometry device.
lO) C X-ray, (41) is an X-ray source, and (42) is an X-ray spectroscopic detector.

As shown in Fig. 7, the conventional X-ray absorption spectrum measuring device collects X-rays (10) from an X-ray source (41) using an X-ray tube.
The sample (6) is irradiated with X-rays (10), and the X-rays (10) transmitted through the sample (6) are detected by an X-ray spectrometer (42).

Since a large amount of X-ray intensity is required to measure the X-ray absorption spectrum, a high-output X-ray tube is used as the X-ray source (41).

In addition, in recent years, in order to secure a large amount of X-ray intensity, synchrotron radiation (when high-speed electrons make circular motion in a magnetic field) has been developed by using particle accelerators or by using linear accelerators and electron storage rings. Attempts have been made to utilize the light emitted by X-rays, which has a continuous spectrum over a wide range from visible light to X-rays, as an X-ray source for X-ray absorption spectrometers.

[Problems to be Solved by the Invention] Since the conventional X-ray absorption spectrum measuring device as described above is configured as described above, in a device that uses an X-ray tube as an X-ray source, Due to the spread of X-rays that are diffused over a wide range from the sphere and the difficulty of bringing the sample and the X-ray source close together, even if a large-capacity X-ray tube is used, the unit that irradiates the sample is difficult. It is difficult to ensure sufficient X-ray intensity per area, and it may take several days to several weeks to obtain accurate measurement data. X1 again! Due to the expansion of the irradiation area, the sample size has to be increased, and the size of the spectroscopic crystal that spectrally disperses the X-rays that have passed through the sample must also be increased, and the X-ray source must be kept stable for a longer period of time. However, it is difficult to automatically operate the equipment.

Further, when synchrotron radiation is used as an X-ray source, there are problems such as the huge cost and installation space required.

The present invention has been made to solve these problems, and an object of the present invention is to provide an X-ray absorption vector measuring device that is small, inexpensive, and capable of obtaining highly accurate measurement data through automatic operation.

[Means for Solving the Problems] An X-ray absorption spectrometer according to the present invention utilizes an X-ray source with electron beam excitation, and includes an electron beam generating section, an X-ray source, a sample, an X-ray spectrometer crystal, and a detector. and were arranged in the same vacuum body.

[Function] In this invention, an electron beam excitation X-ray source is used, and the electron beam generator, the X-ray source, the sample, the X-ray spectrometer crystal, and the detector are arranged in the same vacuum body. Therefore, it is possible to bring the X-ray source and sample close together, prevent the spread of X-rays due to diffusion, and make it easier to control the X-ray source and sample, making the device suitable for automatic operation. becomes.

[Examples] Examples of the present invention will be described below with reference to the drawings. 1st
The figure is a cross-sectional view showing the outline of the configuration of an X-ray absorption spectrum measuring device that is an embodiment of the present invention. The electron beam generated in (1) is irradiated onto the target to generate X-rays (2> X-ray generation section, and the X-ray spectroscopic detection in (3) that spectrally detects the X-rays that have passed through the sample Department and
It consists of a control section (4) that controls the entire apparatus, (5) a vacuum exhaust system, (6) a thin film sample, and (7) a vacuum exhaust system.
) is an electron gun, (8) is a finely focused electron beam, (9) is an X
The target for ray generation, (lO) is the generated X-ray, (1
1) is the target installation stage, (12) is the electron beam shielding filter, (13) is the sample stage, (14> is the X-ray spectrometer crystal, (1)
5) is a spectroscopic crystal drive unit, (16) is a slit, (
17> is an X-ray detector, (18) is an X-ray detector drive unit, (19> is a control circuit 1 for controlling the spectroscopic crystal drive unit (15), and (20) is an X-ray detector drive unit ( 18), control circuit 2 for controlling (21)
A line measurement circuit, (22) a processing device composed of a CPU and an interface, and (23) a display section.

As shown in FIG. 1, the X-ray absorption spectrum measuring device according to the present invention includes an electron beam generating section (1), an X-ray generating section (2), a sample (6), and an X-ray spectroscopic detecting section (3). It is arranged inside the body, and drives a vacuum evacuation device (5) to ensure the same vacuum state at the same time.

Next, the operation will be explained. The electron beam (8) generated by the electron gun (7) is
The beam is narrowed down and irradiated onto a target (9) for generating X-rays. By being irradiated with the electron beam (8), X-rays (10) are generated from the target (9) due to electron beam excitation, and the generated X-rays (10) pass through the electron beam shielding filter (1).
2) is irradiated onto the sample (6>).

This electron beam shielding filter (12) is connected to the target (9).
High-energy electrons reflected from the surface (backscattered electrons)
This is to prevent the generation of noise due to entering the X-ray detector (17), and in the example, a shielding thin film that easily transmits X-rays and shields electron beams is used, but it is not necessary to use a thin film for capturing electrons. A magnet or an electrostatic deflection plate may be used, and between the sample (6) and the X-ray spectroscopic crystal (14), or
It may be provided between the line spectrometer crystal (14) and the X-ray detector (17).

The X-rays <10> irradiated onto the sample (6) undergo absorption unique to the sample (6), transmit through the sample (6), and enter the X-ray spectroscopy crystal (14). In the X-ray spectroscopy crystal (14), Br
agg diffraction condition nλ = 2d-sinθ (n: reflection order, λ: wavelength of X-ray, d: interplanar spacing of spectroscopic crystal, θ:
The incident angle of the X-rays> is diffracted and spectrally separated, and then incident on the X-ray detector (17) through the slit (16), where the X-ray detector (17) converts it into an electrical signal and generates X-rays. X-ray intensity is measured by a measurement circuit (21).

Note that the X-ray spectrometer crystal (14) is the spectrometer crystal drive unit (
The X-ray detector (17) is driven by the X-ray detector drive unit (18), and its driving is controlled by the control circuit 1 (19).
(20), and each control circuit (19) and (20) is controlled by a processing device (22).
It is controlled by commands from the internal CPU, and various diffraction conditions can be automatically set. In addition, the intensity of the X-rays measured by the X-ray measurement circuit (21) is CP
Data processing can be performed using U, and automatic operation of the entire device is made possible by the control section (4).

As described above, in this invention, the target (9) is irradiated with the electron beam (8), and the excitation of the electron beam (8) generates X-rays (10).
, the X-ray source can be made smaller and more energy efficient than when using cyclotron synchrotron radiation or when using an X-ray tube.

In addition, the X-ray generation section (1), the sample (6), and the X-ray spectroscopic detection section (
3) can be installed in the same vacuum body, the distance between the X-ray source and the sample (6) can be kept close within 10 mm to 20 mm, and the spread due to diffusion of the X-ray (10) can be reduced. The X-ray intensity per unit area irradiated to the sample (6) can be increased, and the sample (6) to be measured can be
6> can be made small, and it is also possible to measure minute parts.

Since the sample (6) can be made smaller, it becomes easier to hold the sample (6). Also, being able to make the sample smaller makes it easier to make the thickness of the thin film sample (6) uniform, which makes it easier to hold the sample (6). <6> has the advantage of easily preventing the occurrence of raw pinholes.

FIG. 2 is a diagram showing a second embodiment of the present invention, in which the same reference numerals as in FIG. 1 indicate the same or corresponding parts, and (30
〉 indicates a secondary electron detector, and (31) indicates the generated secondary electrons. In the embodiment shown in Fig. 2, a secondary electron detector (30) is provided, and the surface observation of the target (9〉) is performed using secondary electrons. This was done with a statue.

Note that a backscattered electron detector (not shown) may be provided in place of the secondary electron detector (30), and the surface of the target (9) may be observed using a backscattered electron image.

Further, by providing a secondary electron detector (30) at a predetermined position and placing an observation sample on the target installation stand (11), the functions of a conventional scanning electron microscope (SEM) can be easily added.

Furthermore, place the observation sample on the target installation stand (11),
A function as an electron probe microanalyzer (EPMA) can be easily added by spectroscopy of characteristic X-rays generated from a minute portion by irradiation with an electron beam (8) using an X-ray spectroscopy detection section (4). I can do it.

Furthermore, it becomes possible to add the function of a scanning transmission electron microscope (STEM), and also to add the function of a transmission electron microscope (TEM) by using the electron beam generating section (1).

FIG. 3 is a diagram showing a third embodiment of the present invention, in which the same reference numerals as in FIG. 1 indicate the same or corresponding parts, and (32
〉 is a target driving device, and (33〉 is a target driving unit.) In the embodiment shown in Fig. 3, the target (
9) A target drive device (
32), and this target drive device (
32) can appropriately move the target (9) on the X-Y plane whose two axes are the irradiation direction of the electron beam (8) while being controlled by the target drive unit (33>) according to commands from the CPU. This makes it possible to prevent the X-ray generation efficiency from decreasing due to the generation of contamination due to long-term irradiation of the surface of the target (9) with the electron beam (8).

FIG. 4 and FIG. 5 are diagrams showing a fourth embodiment of this invention,
In each figure, the same reference numerals as in FIG.
X II (10
) The sample (6) is taken in and out of the X-ray (10) alternately for each wavelength (energy), and changes in the electron beam (8) and formation on the target (9) surface are avoided. Even if the intensity of the X-rays (10) irradiated to the sample (6) fluctuates due to contamination, and there are fluctuations in the setting conditions, measurement errors due to such fluctuations are prevented. .

That is, the sample (6) is exposed to X-rays (
10〉, and alternately measure the X-ray intensity (I〉) transmitted through the sample (6〉) and the X-ray intensity (Io) when there is no sample (6). natural logarithm μ of the ratio
x=4. By taking (IO/I), fluctuations in X-ray intensity are canceled out. In addition,
μ indicates the linear absorption coefficient of X-rays, and X indicates the thickness of the sample (6).

Furthermore, (a) to (d) shown in FIG. 5 are diagrams showing an example of the configuration of the sample stage 34) when loading and unloading the sample (6), and each sample (6) is It is bonded to the sample stage <34> using carbon paste or the like so as not to impede the transmission of the sample. Furthermore, by using a sample stage (34) on which two sets of samples (6) as shown in FIGS. 5(b) to (d) can be placed, 1. Same vacuum conditions can be achieved.

By measuring two sets of the same type of sample (6) under the same X-ray irradiation conditions and calculating the average value, it is possible to perform measurements without errors, and to set 17 vacuum conditions and X-ray irradiation conditions. Two sets of different types of samples (6) can be measured continuously without destroying the sample.

FIG. 6 is a diagram showing a fifth embodiment of the present invention, in which the same reference numerals as in FIG. 1 indicate the same or corresponding parts, and (37
) is sample cooling device, (38〉 is liquid nitrogen insertion tube, (39
〉 is a control valve that controls the amount of liquid nitrogen inserted, and (40) is a cylinder that stores liquid nitrogen.

In this example, excessive drift of the sample (6) itself,
In order to reduce the influence of lattice vibrations, a sample cooling means is provided that cools the sample (6) using liquid nitrogen.

The device according to the present invention has a control unit (4) with a built-in CPU.
), the operation of the entire apparatus is automatically operated, and as shown in Figures 4 and 5, the sample drive device (35
In order to avoid the influence of drift when driving the sample (6) using It goes without saying that operations such as increasing the number of measurement points and the number of X-ray measurements can also be performed automatically by the control section (4).

[Effects of the Invention] As explained above, the present invention utilizes an X-ray source by electron beam excitation, and arranges an electron beam generating section, an X-ray source, a sample, an X-ray spectrometer crystal, and a detector in the same vacuum body. This method prevents the spread of X-rays due to diffusion, brings the X-ray source and sample closer together, improves analysis accuracy, and makes the device smaller and cheaper. This has the effect of making it easier to control the X-ray source and sample, making the device suitable for automatic operation using a computer.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of this invention, FIG. 2 is a diagram showing a second embodiment of this invention, FIG. 3 is a diagram showing a third embodiment of this invention, FIG. FIG. 5 shows a fourth embodiment of the invention, FIG. 6 shows a fifth embodiment of the invention, and FIG. 7 shows a conventional device. (1) is the electron beam generation section, (2) is the X-ray generation section, (3) is the X-ray spectroscopic detection section, (4) is the control section, (5) is the evacuation device, (6> is the sample, ( 7> is an electron gun, (8) is an electron beam,
(9) is the target, (10) is the X-ray, (11) is the target installation stand, (12) is the electron beam shielding filter, (13)
) is the sample stage, (14) is the X-ray spectroscopic crystal, (15> is the spectroscopic crystal drive unit, (16) is the slit, and (17) is the
ray detector, (18) is an X-ray detector drive unit, (19)
) is control circuit 1, (20) is control circuit 2, (21) is X
A line measurement circuit, (22) a processing device, (23) a display unit,
(30) is a secondary electron detector, (32) is a target drive device, (33) is a target drive unit, (34> is a sample stage, (35> is a sample drive device, (36) is a shaft, (37>) (38) is a liquid nitrogen insertion tube, (39) is a control valve, and (40) is a cylinder. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (4)

[Claims] (1) In an X-ray absorption spectrum measurement device that transmits X-rays through a sample, detects the intensity of the transmitted X-rays, and measures the X-ray absorption spectrum of the sample, an electron beam generation unit that generates an electron beam; The electron beam generated in this electron beam generating section is
An X-ray generation section has an X-ray source that generates X-rays through electron beam excitation by irradiating a target for ray generation, and a sample is placed in the irradiation direction of the X-rays generated by this X-ray generation section. an X-ray spectroscopy detection section having an X-ray spectroscopy crystal and a detector for dispersing and detecting the X-rays transmitted through the electron beam, and a control section for controlling the entire device; An X-ray absorption spectrum measuring device characterized in that a source, the sample, the X-ray spectroscopy crystal, and the detector are arranged in the same vacuum body. (2) The X-ray absorption spectrum measuring device according to claim 1, further comprising target driving means for driving the target for generating X-rays within the same vacuum body. (3) A sample driving means is provided that continuously positions and removes the sample at predetermined intervals in the irradiation direction of the X-rays irradiated into the same vacuum body, and the intensity of the X-rays transmitted through the sample is I, the natural logarithm of the intensity ratio when the X-ray intensity when the sample is removed is I_0 μx = l_n (I_0/I) (μ: linear absorption coefficient of X-rays, x: thickness of the sample) X according to claim 1 or 2, characterized in that the X-ray absorption spectrum is measured by
Line absorption spectrum measuring device. (4) The sample placed in the same vacuum body is cooled using a sample cooling means,
The X-ray absorption spectrum measuring device according to item 2 or 3.