JPH0332737B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron beam macro analyzer device, and more particularly, to an electron beam macro analyzer device that can analyze a sample with high measurement accuracy.

For example, in order to map the elements contained in steel sheets, etc., conventionally, a spectroscopic crystal is used to separate the fluorescent X-rays obtained by scanning the sample with an electron beam, and the X-rays separated by this spectroscopic crystal are detected. A macro analyzer device comprising an X-ray detector is used.

This type of conventional macro analyzer device has a first
As shown in the figure, an electron beam generator 3 is provided for scanning an analysis surface 2a of a sample 2 placed on a table 1 with an electron beam. The electron beam generator 3 is configured to focus electrons output from the electron gun 4 using an electron lens 5, and cause the focused electron beam 6 to perform vertical and horizontal scanning according to a current flowing through a deflection coil 7. has been done. When the analysis surface 2a is scanned by the electron beam 6, the fluorescent X-rays 8 emitted from the analysis surface 2a enter the spectroscopic crystal 10 through the solar slit 9, are reflected there, and are transmitted through another solar slit 11. The light enters the X-ray detector 12 and is converted into an electrical pulse signal. The pulse train signal PT from the X-ray detector 12 is then passed through the amplifier 13 to the pulse height analyzer 14.
The pulse height discrimination data D from the pulse height analyzer 14 is processed in the arithmetic circuit 15, thereby obtaining analytical data regarding the distribution of the target element in the sample.

By the way, in the electron beam macro analyzer device having such a configuration, the solar slit 9,
Due to imperfections in the manufacturing of the slit plates 11, that is, imperfections in the parallelism of the slit plates and uneven stacking, the amplitude of the electrical signal obtained from the X-ray detector 12 changes when the electron beam 6 is swung. The problem is that it cannot be avoided. In order to eliminate this problem, generally the X-ray detector 1
Using the property that the ratio between the primary component and the secondary component of the fluorescent X-ray of interest outputted from 2 after spectroscopy is not affected by the above-mentioned imperfection of the solar slit, the fluorescent X-ray is calculated using a method called the ratio method. Although we are conducting line analysis, we are using the gas flow type that has traditionally been used.
Some detectors using Ar proportional counters have low detection efficiency for high-energy X-ray components, so the detected value of the secondary component is significantly smaller than the detected value of the primary component, and the statistical accuracy of the ratio of the two is reduced. This has caused a problem in that the measurement accuracy has decreased significantly.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide an electron beam macro analyzer device which eliminates the above-mentioned drawbacks of the prior art and is capable of analyzing a sample with high precision.

A feature of the present invention for achieving the above object is that an electron beam macro analyzer device is configured to analyze fluorescent X-rays emitted from a sample using a spectroscopic crystal and then convert the fluorescent X-rays into electrical signals using an X-ray detector. A first detector for detecting the primary component of the X-rays and a second detector for detecting the secondary components are arranged in series along the incident direction of the spectroscopic X-rays, and the spectroscopic X-rays from the spectroscopic crystal are The primary component and the secondary component are detected separately and simultaneously by a first detector and a second detector, respectively, and the sample is analyzed based on the ratio of the sizes of the detected primary and secondary components. That's what I did.

A gas flow type Ar proportional counter tube can be used as the first detector, while an enclosed type Xe proportional counter tube can be used as the second detector, and the gas flow type Ar proportional counter tube can be inserted through a pair of mylar windows. By making the spectral X-rays that have passed through the gas flow type Ar proportional counter tube also enter the enclosed Xe proportional counter tube, information on the primary and secondary components of the spectral X-rays can be obtained from each proportional counter tube. can be taken out.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 2 shows an embodiment of an electron beam macro analyzer device according to the present invention. This electron beam macro analyzer device 20 scans an analysis surface 2a of a sample 2 placed on a table 1 with an electron beam 6 from an electron beam generator 3, thereby scanning the fluorescent light X emitted from the sample 2. The point that the line 8 is dispersed by the solar slits 9, 11 and the spectroscopic crystal plate 10 is the same as the conventional apparatus shown in FIG. Therefore, in FIG. 2, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and their explanations will be omitted.

The electron beam macro analyzer device 20 separately and simultaneously detects the primary component and the secondary component of the spectroscopic X-ray 21 obtained through the solar slit 11.
A ray detector 22 and a second X-ray detector 23 that detects secondary components of the spectral X-rays 21 are arranged in series along the traveling direction of the spectral X-rays 21.

FIG. 3 shows first and second X-ray detectors 22, 2.
3 in series are shown in detail. 1st X
The line detector 22 is a gas flow type Ar proportional counter tube, and the peripheral wall of its cylindrical casing 24 has a pair of windows 25 each made of mylar with a thickness of about 1 μm.
26 is formed. This pair of windows 25, 26
are formed on the peripheral wall of the casing 24 so as to face each other across the communication axis, and these windows 2
5 and 26 are arranged perpendicularly to the traveling direction of the spectroscopic X-rays 21. Therefore, spectroscopic X-ray 2
1 once enters the first X-ray detector 22 through the window 25, and then enters the first X-ray detector 2 through the window 26.
You can get out of 2. 1st X-ray detector 2
On the rear side of 2, a second X-ray detector 23 is arranged in series with the first X-ray detector 22 along the traveling direction of the spectroscopic X-rays 21, and the cylindrical casing of the second X-ray detector 23 A beryllium window 28 formed in the peripheral wall of the first X-ray detector 27 is provided so as to face the window 26 of the first X-ray detector 22 . Therefore, the spectral X-rays 21 that have passed through the first X-ray detector 22 as described above
can enter the second X-ray detector 23 through the beryllium window 28.

The characteristics of the gas flow type Ar proportional counter tube and the enclosed type Xe proportional counter tube are as shown in Figure 4. The former has high efficiency against low-energy X-rays, and the latter has high efficiency against high-energy X-rays. is getting higher.
Therefore, if we consider the case of analyzing the manganese element in a steel plate, for example, the distribution of X-ray intensity will be as shown in Figure 5. is the first
Each component can be detected with high efficiency by detecting the components with the first X-ray detector 22 and, on the other hand, detecting the relatively high-energy secondary components with the second X-ray detector 23, which is an enclosed Xe proportional counter tube. Can be done.

Therefore, the output from each X-ray detector 22, 23
D ₁ and D ₂ are as shown in FIGS. 6a and 6b. Here, we have explained the case where the element to be analyzed is Mn, but the case is exactly the same for other elements, and the wavelengths of the primary and secondary components of fluorescent X-rays are twice as different. , it is only necessary to select an X-ray detector that is effective for each component, depending on the element of interest.

Returning to FIG. 2, the signals D ₁ and D ₂ outputted from the respective x-ray detectors 22 and 23 in this manner are amplified by the correspondingly provided amplifiers 29 and 30, and then sent to the wave height discrimination circuit 31, 32, where the intensity of Mn-Kα (n=1) and the intensity of Mn-Kα (n=
2) and the intensities are respectively detected. This detection result
N ₁ and N ₂ are input to the calculation circuit 33, where the ratio of both inputs N ₁ and N ₂ is calculated in the same way as in the conventional case, and according to the calculation result, necessary operations such as mapping of the analysis surface 2a are performed. data processing.

According to such a configuration, a dedicated X-ray detector is provided for each order component of the spectroscopic X-rays, and the detection can be performed with high efficiency, so that N ₁ /
The value of N ₂ can be set to a suitable value, and it is possible to effectively prevent the value of N ₂ from becoming extremely small as in the conventional case. As a result, N ₁ /
The statistical error in the N ₂ value is reduced, the elemental analysis of the sample can be performed with high measurement accuracy, and highly reliable data can be provided.

In the above embodiment, the target X-rays can be detected with high efficiency over a wide range of wavelengths by combining the gas flow type Ar proportional statistics tube and the enclosed Xe proportional counter tube, but the present invention is not limited to this combination, for example, the first and second
Each of the two X-ray detectors may be used as an ionization chamber, and an appropriate combination can be determined depending on the purpose of analysis.

According to the present invention, as described above, desired spectroscopic X-rays can be reliably detected and a sample can be analyzed with high measurement accuracy.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a conventional electron beam macro analyzer device, Fig. 2 is a schematic diagram of an electron beam macro analyzer device according to the present invention, and Fig. 3 is an arrangement of the X-ray detector shown in Fig. 2. FIG. 4 is a graph showing the characteristics of the X-ray detector shown in FIG. 2; FIG. 5 is a graph showing the spectrum of fluorescent X-rays from manganese; FIG. 6a, FIG. b is a graph showing the outputs of the X-ray detectors shown in FIG. 2; 1... Table, 2... Sample, 6... Electron beam, 8... Fluorescent X-ray, 10... Spectroscopic crystal plate, 20
...Electron beam macro analyzer device, 21...
Spectroscopic X-ray, 22...1st X-ray detector, 23...1st
2X-ray detector, 31, 32... Wave height discrimination circuit, 3
3... Arithmetic circuit.

Claims (1)

[Claims] 1. An electron beam generator for irradiating a sample surface with an electron beam, a spectroscopic crystal for spectrally dispersing X-rays emitted from the sample surface by the electron beam irradiation, and detecting the X-rays spectrally separated by the spectroscopic crystal. In an electron beam macro analyzer device comprising an X-ray detector that converts into an electrical signal, the X-ray detector is configured to detect first X-rays arranged linearly along the X-ray emission direction separated by a spectroscopic crystal. The first X-ray detector has a pair of mylar windows and detects the primary component of the X-rays separated by the spectroscopic crystal and converts it into an electrical signal. 2The X-ray detector detects the secondary component of the X-rays separated by the spectroscopic crystal, converts it into an electrical signal, and calculates the ratio of the signals of the primary X-ray and the secondary X-ray that are converted to the electrical signal. An electron beam macro analyzer device characterized in that it analyzes a sample.