JPH0247698B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for line analysis of a sample state or for drawing a two-dimensional state distribution image (state map) in EPMA (also referred to as electron beam microanalyzer or XMA). Regarding.

(Prior art) EPMA is originally a means of elemental analysis and does not directly reveal the existence of compounds. That is, for example, metal Fe can also be used as FeO, Fe ₃ O ₄ or Fe ₂ O ₃ .
Fe is usually treated the same way. However, the spectrum of characteristic X-rays detected by EPMA changes depending on the state of the analysis sample (mainly the chemical bond state). Therefore, state analysis is often performed based on changes in the spectrum of this characteristic X-ray, but since the changes in the spectrum are generally small, so-called point analysis is performed in which the details of the spectrum are actually measured and analyzed at each measurement point. The reality is that state analysis is performed in mode. Therefore, it is not generally practiced to obtain a two-dimensional distribution image of only a certain chemical bonding state. As a special example, in the case of sulfide and sulfide, the wavelength shift of the SL band spectrum is large, so by setting the spectrometer to the wavelength of the peak unique to each compound, A two-dimensional distribution image can be obtained. In addition, CuO has a unique peak that does not exist in Cu ₂ O, so by setting the spectrometer to the wavelength of that peak,
A two-dimensional distribution image of CuO can be obtained (for example, the 30th Annual Meeting of the Analytical Society of Japan (1981) Proceedings 374
(see page).

(Problem to be solved by the invention) However, the normal wavelength range of EPMA (1 to 100
It is rare for a phenomenon such as the SL band to appear in Å). Also, regarding CuC and Cu ₂ O, CuO
However, since there is no unique peak for Cu ₂ O, it is not possible to obtain a distribution image of Cu ₂ O. As described above, the method of obtaining a distribution image by finding a peak unique to a specific bonding state and setting the spectrometer at that unique peak wavelength cannot be generally applied.

Additionally, although it is not difficult to automate spectrum analysis in point analysis mode, when the number of measurement points is tens to tens of thousands, such as in line analysis or two-dimensional distribution images, the processing time and memory capacity become enormous. becomes virtually impossible.

The present invention aims to provide a method for obtaining a distribution image of only specific states for a collection of states such as chemical bond states whose characteristic X-ray spectra change to such an extent that they can be analyzed in point analysis mode. This is the purpose.

(Means for Solving the Problems) In the present invention, the detection wavelengths of the spectrometer of the EPMA apparatus are set in advance to two wavelengths, and the characteristic X-rays from each measurement point of the analysis sample are adjusted to the two wavelengths. A state map is obtained by detecting the wavelength and outputting only the measurement points where the detection intensity ratio at these two set wavelengths falls within a predetermined range.

In the first invention, the two wavelengths set in advance are one of characteristic X-rays indicating a specific bonding state of a specific element.
The peak wavelength of two peaks and the wavelength of the midpoint of the peak.

In the second invention, the two wavelengths set in advance are two wavelengths of characteristic X-rays indicating a specific bonding state of a specific element.
is the peak wavelength of each of the associated peaks.

In the third invention, the two preset wavelengths are one of characteristic X-rays indicating a specific bonding state of a specific element.
These are the wavelengths halfway between the long wavelength side and the short wavelength side of the peak wavelength of each peak.

(Operation) FIG. 1 shows the method of the present invention in the case where the peak wavelength of the characteristic X-ray spectrum shifts due to a change in the state of chemical bonding or the like.

Now, suppose that the spectrum of a certain element in its first state has a peak wavelength of λ ₁ and a wavelength shifted from it, for example, by about 1/2 of the half width, as shown by symbol 1, λ ₂ . 2 set at wavelengths λ ₁ and λ ₂ , respectively.
Assume that this spectrum is detected by two spectrometers, the detected intensities are I ₁ and I ₂ , and there is a relationship between them: I ₁ ≧αβ ₁ I ₂ (1).

Next, if the spectrum of this element in the second state has a shifted peak wavelength compared to the spectrum in the first state, as shown by symbol 2, then the wavelengths λ ₁ , λ If _the characteristic X-rays _of the element in the _second state _are detected using two spectrometers _{set at} Become.

Therefore, it is necessary to detect the characteristic X-rays of the element at preset wavelengths λ ₁ and λ ₂ , compare the detected intensities, and output only the measurement points whose detected intensity ratio satisfies equation (1). In this case, the line analysis or two-dimensional distribution image of the first state is displayed, and if only the measurement points whose detected intensity ratio satisfies equation (2) are output, the line analysis or two-dimensional distribution image of the second state can be displayed. Is displayed. Here, α is a spectrometer for measuring the intensity I ₁ at a specific wavelength λ ₁ and a spectrometer for measuring the intensity I 1 at a specific wavelength λ ₂
This is a factor introduced to match the performance of spectrometers for measuring intensity I ₂ at , and β ₁ is a factor indicating the amount of wavelength shift.

Figure 2 shows the method of the present invention when the intensity ratio of related peaks such as Lα and Lβ of Fe and K satellite α ₃ and α ₄ of Mg, Al, Si, etc. changes depending on the state of chemical bonding, etc. .

The detection wavelengths of the two spectrometers are set to the peak wavelengths λ ₃ and λ ₄ of the two related peaks 3 and 4. In the first state, the detected intensities I ₁ and I ₂ of the characteristic X-rays at the set wavelengths λ ₃ and λ ₄ satisfy the relationship I ₁ ≧αβ ₂ I ₂ ...(3), and in the second state, I ₁ <αβ ₂ I ₂ ……If the relationship of (4) is satisfied, the characteristic X of each measurement point
By determining whether the line spectrum belongs to equation (3) or (4), a state-specific line analysis or a two-dimensional distribution image can be obtained. Here, β ₂ is a factor indicating the intensity ratio of related peaks.

FIG. 3 shows the method of the present invention when the symmetry of the spectral waveform of characteristic X-rays changes due to changes in states such as chemical bond states.

In this case, the set wavelengths of the spectrometer are set to wavelengths λ ₅ and λ ₆ that are shifted by about 1/2 of the half width, for example, on the longer wavelength side and the shorter wavelength side with the peak wavelength in between. The relationship between the detected intensities I ₁ and I ₂ of characteristic X-rays at these set wavelengths is I ₁ > αβ ₃ I ₂ ...(5) I ₁ = αβ ₃ I ₂ ...(6) or I ₁ < By determining which of αβI ₂ (7) it belongs to, a line analysis or a two-dimensional distribution image for each state to which each spectrum waveform belongs can be obtained.

FIG. 4 shows the method of the present invention in the case where the half-width of the characteristic X-ray spectrum changes due to a change in the state of chemical bonding or the like.

For example, if the spectral waveform changes as shown by symbols 5 and 6 due to a change in the coupling state, the set wavelength of the spectrometer should be set to the peak wavelength λ ₁ as shown in FIG. It is sufficient to set the wavelength λ ₂ to be shifted by about 1/2 of the half width. If the half-width of the spectrum changes, the detection intensity ratio at each set wavelength also changes, so line analysis or two-dimensional distribution images for each state can be obtained in the same way as in the case of FIG. 1.

(Embodiment) FIG. 5 shows an embodiment of an apparatus for carrying out the present invention.

Reference numeral 10 denotes an analysis sample, and an electron beam 12 emitted from an electron gun 11 illuminates a measurement point on the analysis sample 10 through a converging lens 13 and an objective lens 14, and is scanned over the analysis sample 10 by a scanning coil 15.
The analysis sample 10 irradiated with the electron beam 12 emits characteristic X-rays 16, secondary electrons, and the like.

In this embodiment, in order to detect characteristic X-rays 16, a first wavelength-dispersive spectrometer has a spectroscopic crystal 17 and a detector 18, and a second wavelength-dispersive spectrometer has a spectroscopic crystal 19 and a detector 20. It is equipped with Both spectrometers have equivalent performance and are set to detect X-rays of the wavelengths shown in FIGS. 1-4. That is, if the set wavelength of one spectrometer is λ ₁ , the set wavelength of the other spectrometer is λ ₂ , if one is λ ₃ , the other is λ ₄ , or if one is λ ₅ , the other is λ _6. That's how it is.

In this case, the detectors 18, 20 may be of any type, such as proportional counters or position sensitive detectors. Further, although both spectrometers are preferably provided close to each other as shown in the figure, they may be provided at positions separated from each other.

In this apparatus, characteristic X-rays 16 emitted from an analysis sample 10 are separated into different wavelengths by spectroscopic crystals 17 and 19, and are simultaneously incident on detectors 18 and 20, where they are detected simultaneously or in chronological order.

Assuming that the detection intensities of both detectors 18 and 20 are I ₁ and I ₂ , I ₂ is set to αβiI by α setting means 21 and βi (i=1, 2 or 3) setting means 22, as shown in FIG. ₂ , the comparison means 23 transforms I ₁
is compared with αβiI ₂ to determine whether the value represents a predetermined state. In this way, by displaying the determination results in real time while passing through the measurement points, a line analysis or two-dimensional distribution image of a specific state is displayed.

The output signals from the detectors 18 and 20 are once stored in the memories 24 and 25 together with the position information of the measuring point in the form of I ₁ and αβiI ₂ as shown in FIG. 7, and then compared by the computer 26. Alternatively, as shown in FIG. 8, I ₁ and I ₂ may be displayed together with the position information of the measurement points in the memories 27 and 28.
After storing, the computer 29 may add the coefficients α and βi, perform a comparison, and display the results.

FIG. 9 represents another embodiment of the apparatus for carrying out the invention.

In this embodiment, the spectrometer is one wavelength-dispersive spectrometer having a position detection type detector 30 and a spectroscopic crystal 31, and the intensity detection in the position detection type detector 30 is performed at one set wavelength (for example, λ ₁ ). This is different from the embodiment shown in FIG. 5 in that the detection is performed at two locations: one at a position corresponding to λ 2 and the other at a position corresponding to the other set wavelength (for example, λ ₂ ).

When performing intensity measurements at set wavelengths λ ₁ and λ ₂ with two independent spectrometers, each is set to a fully spectral state, whereas a single spectrometer with a position-sensitive detector is used. When simultaneously measuring the intensities at positions corresponding to wavelengths λ ₁ and λ ₂ with an instrument, the spectral conditions become approximate, but this is not true for the purpose of comparing intensities between wavelengths that are close to each other as in the present invention. There is no problem above.

As a result, in this embodiment, as shown in FIG. 10, detection signals I ₁ and I ₂ at mutually different set wavelengths are obtained from two locations of one position detection type detector 30 simultaneously or in time series. It will be done. These two detection signals I ₁ ,
By processing I ₂ in real time as shown in the same figure, or by processing it after being stored in the memory 24, 25 or 27, 28 as shown in FIG. 7 or 8, the line in a specific state can be Analysis or two-dimensional distribution lines can be displayed.

(Effects of the Invention) As described above, according to the present invention, the detection wavelength of the spectrometer of the EPMA apparatus is set to the peak wavelength of one peak of a characteristic X-ray indicating a specific bonding state of a specific element and the midpoint of that peak. Specify in advance the characteristic X-ray, the peak wavelength of each of two related peaks, or the wavelength midway between the long wavelength side and short wavelength side of the peak wavelength of one peak, and perform each measurement of the analytical sample. Characteristic X-rays from a point are detected at the two set wavelengths, and only those measurement points where the detection intensity ratio at those two set wavelengths falls within a predetermined range are output to obtain a status map. If it is a state such as a chemical bond state whose spectra change mutually to the extent that it can be analyzed in line analysis mode, it can be displayed individually, and line analysis or 2 Maps such as dimensional distribution images can be created. This greatly enhances the ability of EMPA, which was previously limited to merely showing elemental analysis, and makes it possible to supply state analysis, which is extremely important information for material analysis.

Further, in the present invention, since the wavelength to be detected is set in advance without scanning with a spectrometer, the capacity of the memory for storing measurement data can be small, and the processing circuit can also be simple.

[Brief explanation of drawings]

1 to 4 are diagrams showing characteristic X-ray spectra for explaining the method of the present invention, FIG. 5 is a schematic diagram showing an embodiment of the apparatus for carrying out the present invention, and FIGS. 6 to 8 is a block diagram showing a detection signal processing system of the same embodiment, FIG. 9 is a schematic diagram showing another embodiment of an apparatus implementing the present invention, and FIG. 10 is an example of a detection signal processing system of the same embodiment. FIG. 1 to 6...Characteristic X-ray peak, 16...Characteristic X
Line, 17, 19, 31... Spectroscopic crystal, 18, 20
...Detector, 23...Comparison means, 26, 29...
Computer, 30...Position detection type detector, λ ₁ ~
λ ₆ ...Setting wavelength, I ₁ , I ₂ ...Detection intensity.

Claims (1)

[Claims] 1. The detection wavelength of the spectrometer of the EPMA device is set in advance to the peak wavelength of one peak of characteristic A state mapping method that detects characteristic X-rays from each measurement point of a sample at the two set wavelengths and outputs only the measurement points for which the detection intensity ratio at these two set wavelengths falls within a predetermined range. 2 The detection wavelength of the spectrometer of the EPMA device is set in advance to the peak wavelength of each of the two related peaks of characteristic X-rays that indicate the specific bonding state of the specific element.
A state mapping method that detects characteristic X-rays from each measurement point of an analysis sample at the two set wavelengths and outputs only the measurement points for which the detection intensity ratio at these two set wavelengths falls within a predetermined range. 3. Set the detection wavelength of the spectrometer of the EPMA device in advance to a wavelength midway between the long wavelength side and short wavelength side of the peak wavelength of one peak of the characteristic X-ray that indicates the specific bonding state of a specific element. , a state mapping method in which characteristic X-rays from each measurement point of an analysis sample are detected at the two set wavelengths, and only measurement points where the detected intensity ratio at these two set wavelengths are within a predetermined range are output. .