JPH0361841A - Attachment for measuring x-ray absorption spectrum - Google Patents

Abstract

PURPOSE:To prevent expansion of X-rays due to diffusion and to improve analyzing accuracy by utilizing the electron beam generating part and the sample stage in an electron beam projecting apparatus, using the parts for an X-ray source for generating X-rays by the excitation with an electron beam, and arranging the X ray source, a sample, an X-ray spectrum crystal and a detector in the same vacuum body. CONSTITUTION:An electron beam 8 generated from an electron gun 30 is nassrowed to the diameter of several mum or less with an electromagnetic lens which is not shown and projected on an X-ray generating target 9. When the electron beam 8 is projected on the target 9, the surface of the target 9 is observed with an image processing part 6 as a scanning electron microscope by observing the image of the secondary electrons. X-rays 10 which are generated from the target 9 are projected on a sample 7 through an electron-beam shielding filter 12. The filter 12 is the filter for preventing the input of the reflected electrons of higher energy into an X-ray detector 17. The X-rays 10 which are projected on the sample 7 undergo the specific absorption of the sample and then passes through the sample 7. The X-rays 10 are incident on an X-ray spectral crystal 14. The X-rays 10 undergo Bragg diffraction and are inputted into an X-ray measuring circuit 21.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention can be incorporated into an electron beam irradiation device such as a scanning electron microscope to perform
d Xray Absorption Fine 5t
structure), XANES (X-ra
y'Absorption Near Edge 5t
The present invention relates to an attachment for measuring X-ray absorption spectra, which analyzes X-ray absorption spectra.

[Prior Art] First, a conventional X-ray absorption spectrum measuring device will be explained.

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 the electronic state and structure in solids such as crystalline and amorphous metal alloys, insulators, and semiconductors. A conventional device for performing analyzes such as EXAFS and XANES is shown in FIG. 6th
The figure shows an outline of the configuration of a conventional X-ray absorption spectrum measurement device. In the figure, (7) is a thin film sample, (10> is an X-ray, (42> is an X-ray source, and (43) is an X-ray It is a spectroscopic detector.

As shown in Fig. 6, the conventional X-ray absorption spectrum measurement device collects X-rays (10) from an X-ray source (42) using an X-ray tube.
The sample (7) is irradiated with X-rays (10), and the X-rays (10) transmitted through the sample (7) are detected by an X-ray spectrometer (43).

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 (42).

In recent years, in order to secure a large amount of X-ray intensity, synchrotron radiation (high-speed electrons move in a circular motion in a magnetic field) has been developed by using a particle accelerator or by using a linear accelerator and an electron storage ring. (sometimes emitted light with a wide continuous spectrum ranging from visible light to X-rays)
Attempts have been made to utilize this as an X-ray source for an X-ray absorption spectrometer.

[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. Furthermore, due to the expansion of the X-ray irradiation area, the sample size must be increased, and the size of the spectroscopic crystal that spectrally spectra the X-rays transmitted through the sample must also be increased. Furthermore, it is difficult to keep the X-ray source stable for a long period of time, making it difficult to automatically operate the apparatus.

Furthermore, when synchrotron radiation is used as an X-ray source, a large amount of cost and installation space is required.

Further, the conventional apparatus has problems due to its configuration, such as having to be an independent apparatus with the sole function of measuring an X-ray absorption spectrum.

This invention was made to solve this problem, and by incorporating it into an electron beam irradiation device and utilizing a part of the functions of the electron beam irradiation device, the original functions of the electron beam irradiation device are impaired. To provide an attachment for measuring X-ray absorption spectra, which can easily measure the absorption spectrum of X-rays without any trouble, can make the device small and inexpensive, and can obtain highly accurate measurement data through automatic operation. It is an object.

[Means for Solving the Problems] The attachment for X-ray absorption spectrum measurement according to the present invention is incorporated into an electron beam irradiation device, utilizes the electron beam generation section and sample stage of the electron beam irradiation device, and performs electron beam excitation. As an X-ray generation source that generates X-rays, this
The radiation source, the sample, the X-ray spectroscopy crystal, and the detector are arranged in the same vacuum body.

[Function] In this invention, the Xl1 is incorporated into an electron beam irradiation device, and is used as an The configuration is such that the source, sample, X-ray spectrometer crystal, and detector are placed in the same vacuum body, so
It becomes possible to measure an X-ray absorption spectrum with high accuracy using an electron beam irradiation device without impairing the original function of the electron beam irradiation device.

[Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1st
The figure is a sectional view schematically showing the configuration of an attachment for measuring X-ray absorption spectra, which is an embodiment of the present invention.
It is composed of an X-ray spectroscopic detection unit (3) and a control unit (4). In the figure, (7> is a sample, (9) is a target for X-ray generation, (11) is a target installation stand, and (12) is a is an electron beam shielding filter, (13) is a sample stage, (14) is an X-ray spectroscopic crystal, (15) is a spectroscopic crystal drive unit, (16> is a slit, (17> is an X-ray detector, and (18) is The X-ray detector drive unit (19) is the spectroscopic crystal drive unit (
15), (20) is X
A control circuit 2 for controlling the ray detector drive unit (18), (21) is an X-ray measurement circuit, (22> is a processing device composed of a CPU and an interface, and (23) is a display section.

Figure 2 shows a scanning electron microscope, which is one of the electron beam irradiation devices to which the attachment shown in Figure 1 is installed.
(SEM) is a diagram schematically showing the configuration of an electron beam irradiation device, (6) is an image processing unit as a scanning electron microscope, (8) is an electron beam, and (30) is an electron beam irradiation device. Gun, (31) is surface observation sample, (32> is sample stage, (33)
) is the generated secondary electron, (34) is the secondary electron detector, (
35) is a scanning coil, (36) is a vacuum exhaust device, and (37) is a scanning coil.
> is CRT.

Figure 2 shows a scanning electron microscope as an example of an electron beam irradiation device, but an electron probe microanalyzer (E
The attachment according to the present invention can be similarly incorporated in any device having an electron beam irradiation device main body (5>), such as a transmission electron microscope (PMA), a transmission electron microscope (TEM), or a scanning transmission electron microscope (STEM).

FIG. 3 is a diagram for explaining a state in which the attachment according to the present invention shown in FIG. 1 is incorporated into the electron beam irradiation device (5) shown in FIG. indicates the same part.

As shown in FIG. 3, the attachment according to the present invention connects the surface observation sample (31) and sample stage (32) of the main body of the electron beam irradiation device (5) to the X-ray generation source (1). target (9) and target installation stand (11)
), and replace the sample section (2) and X-ray spectroscopic detection section (3).
Attach. For convenience of explanation, sample part (2) and
Although the line spectrometer detection section (3) is a separate device, these are normally configured as a separate device. Like this
The radiation source (1), sample section (2), and X-ray spectroscopic detection section (3) are assembled into the electron beam irradiation device (5), and the vacuum exhaust device (36
) to create a vacuum inside, and then remove the X-ray source (1), sample (7), X-ray spectrometer crystal (14), and X-ray detector (17).
and are in the same vacuum state, which is the operating state of this attachment.

Next, the operation will be explained. Electron beam (
8〉 and a few μm by an electromagnetic lens (not shown).
The beam is narrowed down and irradiated onto a target (9) for generating X-rays. When the target (9) is irradiated with the electron beam (8), the surface of the target (9) can be observed using a secondary electron image using the image processing section (6) as a scanning electron microscope.

Note that a backscattered electron detector (not shown) may be provided in place of the secondary electron detector (34), and the surface of the target (9) may be observed using a backscattered electron image.

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 (12) to the sample ( 7) is irradiated.

This electron beam shielding filter (12)
This is to prevent the generation of noise caused by high-energy electrons (backscattered electrons) reflected from the surface of the X-ray detector (17). A thin shielding film is used to shield the
A magnet for electron capture, an electrostatic deflection plate, etc. may be used, or between the sample (7>) and the X-ray spectroscopy crystal (14), or between the X-ray spectroscopy crystal (14) and the XI! detector (17). It may also be provided between the

The X-rays (10) irradiated onto the sample (7>) undergo absorption specific to the sample (7), transmit through the sample (7>), and enter the X-ray spectroscopy crystal (step 4).X-ray spectroscopy crystal In (14), Br
agg diffraction condition nλ = 2d-sinθ (n: reflection order, λ: wavelength of X-ray, d: interplanar spacing of spectroscopic crystal, θ:
After being diffracted at an angle of incidence of
The a detector (17) converts the signal into an electrical signal, and the X-ray measurement circuit (21) measures the X-ray intensity.

Note that the X-ray spectroscopy crystal (14) is a spectroscopy 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), each control circuit (19) and (20> are each 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&l measurement circuit (21) is C
Data processing can be performed using the PU, and the control unit (4) enables automatic operation of the entire device.

As described above, the present invention incorporates the electron beam irradiation device into an Since the source, the sample, the X-ray spectrometer crystal, and the detector are arranged in the same vacuum body, the electron beam irradiation device can be effectively utilized, and when using cyclotron synchrotron radiation or the X-ray tube, The X-ray source can be made smaller and more energy efficient than when using a sphere.

In addition, by providing the X-ray generation source (1), the sample section (2), and the X-ray spectroscopic detection section (3) in the same vacuum body, the X-ray generation source (
1) and the sample (7) can be placed within a short distance of 10 mm to 20 mm, preventing the X-rays (10) from spreading due to diffusion, and reducing the unit area irradiated to the sample (7). The sample to be measured (7
) can be made smaller, and it is also possible to measure minute parts.

Since the sample (7) can be made smaller, it becomes easier to hold the sample (7). Also, since the sample can be made smaller, it is easier to make the thickness of the thin film sample (7) uniform, which makes it easier to hold the sample (7). (7) It has the advantage of easily preventing the occurrence of pinholes that tend to occur.

FIG. 4 is a diagram showing a second embodiment of the present invention, in which the same reference numerals as in FIGS. 1 and 2 indicate the same or corresponding parts, (38) is a target driving device, (39) is a It is a target driving unit. In the embodiment shown in FIG. 4, a target driving device (38) is provided so that the target (9) can be driven in a vacuum. (39) while the target (9
) can be moved appropriately on the X-Y plane with the irradiation direction of the electron beam (8) as the Z axis,
It is possible to prevent the X-ray emission efficiency from decreasing due to the generation of contamination due to long-term irradiation of the electron beam (8) onto the surface of the target (9).

FIG. 5 is a diagram showing a third embodiment of the present invention, in which the same symbols as in FIGS. 1 and 2 indicate the same or corresponding parts, (40) is a sample stage, (41) is a sample It is a driving device. In this second embodiment, the CPU uses the sample drive device (
41〉 is controlled so that the sample (7〉) is taken in and out of the X-ray (10) alternately for each wavelength (energy) of the X-ray (10), and the electron beam (8) The intensity of the X-rays (10) irradiated to the sample (7) will vary due to fluctuations in This is designed to prevent the occurrence of

That is, sample (7) is exposed to X-rays (
10), and alternately measure the X-ray intensity (I) transmitted through the sample (7) and the X-ray intensity when there is no sample (7) Natural logarithm of intensity ratio μx
By taking =Jfl (Io/I), fluctuations in X-ray intensity are canceled. In addition, μ is the linear absorption coefficient of X-rays, and X is the thickness of the sample (7).

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 Figure 5, in order to avoid the influence of drift when driving the sample (7>) using the sample drive device (41). , After driving the sample (7), there is a predetermined waiting time until the start of measurement, and in order to improve analysis accuracy, the number of measurement points and the number of X-ray measurements are increased.
It goes without saying that this can be done automatically using the control unit (4).

[Effects of the Invention] As explained above, the present invention utilizes the electron beam generation section and sample stage of an electron beam irradiation device to create an X-ray source that generates xi due to electron beam excitation, and connects this X-ray source and the sample. X
Since the line spectrometer crystal and the detector are arranged in the same vacuum body, the electron beam irradiation device can be used effectively, and spreading due to X-ray diffusion is prevented, making it easier to connect the X-ray source and the sample. To make the device accessible, improve analytical accuracy, make the device small and inexpensive, and make it easy to control the X-ray source and sample, making the device suitable for automatic operation using a computer. It has the effect of being able to.

[Brief Description of the Drawings] Fig. 1 shows an embodiment of the present invention, Fig. 2 shows the configuration of an electron beam irradiation device incorporating the attachment of the invention, and Fig. 3 shows the operation of the invention. FIG. 4 shows a second embodiment of the invention, FIG. 5 shows a third embodiment of the invention, and FIG. 6 shows a conventional device. (1) is the X-ray source, (2) is the sample section, (3) is the X-ray spectroscopic detection section, (4) is the control section, (5) is the electron beam irradiation device body, and (6) is the scanning electron microscope. Image processing unit as (7
> is the sample, (8> is the electron beam, (9) is the target for X-ray generation, (10) is the X-ray, (11) is the target installation stand, (12) is the electron beam shielding filter, (13) is sample stand,
(14) is an X-ray spectroscopic crystal, (15) 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, (20) is a control circuit 2, (21) is an X-ray measurement circuit,
(22) is a processing device, (23) is a display unit, (30) is an electron gun, (31) is a surface observation sample, (32) is a sample stage, (
33> is the generated secondary electron, (34> is the secondary electron detector, (35) is the scanning coil, (36> is the evacuation device, (
37) is a CRT, (38> is a target drive device, (3
9) is a target drive unit, (4o) is a sample stage, and (41) is a sample drive device. Note that the same reference numerals in each figure indicate the same or corresponding parts. 3 also Fig. 40: Sample stage 41: Sample drive device drive device Fig.

Claims (2)

[Claims] (1) An X-ray generation source having an X-ray generation target that generates X-rays by electron beam excitation, and a sample section in which a sample is placed in the irradiation direction of the X-rays generated by this X-ray generation source;
Equipped with an X-ray spectroscopy detection section that has an X-ray spectroscopy crystal and a detector for spectrally detecting the X-rays that have passed through the sample, and a control section that controls the entire device, the electron beam generation of the electron beam irradiation device is The above X in the same vacuum body as
The X-ray generation source, the sample section, and the X-ray spectroscopy detection section are incorporated into the electron beam irradiation device so that the radiation source, the sample, the X-ray spectroscopy crystal, and the detector are arranged. Re,
An attachment for X-ray absorption spectrum measurement, characterized in that the X-ray generation source is excited by an electron beam generated in an electron beam generation section of the electron beam irradiation device to generate X-rays. (2) The attachment for X-ray absorption spectrum measurement according to claim 1, further comprising target driving means for driving the target for generating X-rays within the same vacuum body. (3) The above-mentioned X irradiated into the above-mentioned same vacuum body
A sample driving means is provided that continuously performs the operation of arranging and removing the sample at predetermined intervals in the irradiation direction of the rays, and the intensity of the X-rays transmitted through the sample is I, and the X-rays when the sample is removed are It is characterized by measuring the X-ray absorption spectrum using the natural logarithm μx=l_n(10/I) of the intensity ratio when the intensity is I_0 (μ: X-ray linear absorption coefficient, x: thickness of the sample) The attachment for X-ray absorption spectrum measurement according to claim 1 or 2.