JP2000235009A - Particle analyzing device by means of electron probe microanalyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a particle analyzing device by means of an electron probe microanalyzer capable of correctly determining the compounds to be analyzed even if particles are small enough to fall under an electron diffusion domain of an electron beam irradiated to a specimen. SOLUTION: In this particle analyzing device, an electron probe microanalyzer, irradiating an electron beam to a specimen and analyzing elements in a specimen surface based on characteristic X-rays emitted from the specimen, is made up of a reflected electron detector 8 or a secondary electron detector 9 for obtaining an electron image of the specimen surface, a means 27 for computing the gravity center of particles in the surface of the specimen, a scanning coil 5 or a specimen-stage motor control circuit 23 for moving the electron beam to the position of the gravity center and fixing it thereto, a WDS 16 or an EDS 17 for quantatively analyzing the elements of the particles, a means 28 for computing atomic ratios from the weight concentrations of the elements based on a result of the quantitative analysis, and a means 29 for determining the compounds based on the atomic ratio, and grouping and totalizing them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for producing a sample having a small particle size smaller than the electron diffusion region of an electron beam irradiated on a sample.
The present invention relates to a particle analyzer using an electron probe microanalyzer (hereinafter abbreviated as EPMA) capable of correctly determining a particle compound.

[0002]

2. Description of the Related Art Conventionally, wavelength dispersion type X-ray spectrometer (WDS)
Or E using an energy dispersive X-ray spectrometer (EDS)
In PMA, characteristic X-rays of a sample are detected, and quantitative analysis is performed by comparison with the X-ray intensity of a standard sample. In addition, continuous analysis is possible by automatic control of the sample stage or the electron beam under computer control. Also, recently, a system that automatically detects particles such as inclusions with a reflected electron image or a secondary electron image, calculates the center of gravity, automatically moves and fixes the electron beam to the center of gravity, and can perform quantitative analysis. Has been built.

Further, in this quantitative analysis, the type of the compound of the obtained particles is automatically determined from the quantified value of each element (weight concentration%) in consideration of its statistical fluctuation and measurement error. A learning function system has been developed in which groups are divided into groups.

[0004]

By the way, in a scanning electron microscope (SEM) or EPMA at present, an electron beam can usually be narrowed down to about 50 to 60 °, and high-resolution observation is possible. However, since the accelerated electrons penetrate deep into the analysis sample and generate X-rays, the X-ray generation region is diffused to about 1 μm.

[0005] For example, when analyzing minute inclusions such as MnS and MgO in iron and steel, as shown in FIG.
With only the above large particles, it is possible to quantitatively analyze the particles themselves almost completely. That is, the accelerated electrons are scattered only in the inclusions and do not diffuse into the surrounding iron region, and thus are not affected by iron in the quantitative analysis. However, as shown in FIG. 2B, when small particles of 1 μm or less are mixed, electrons diffuse to the iron region around the small particles of 1 μm or less. For example, in the case of MnS particles, X-rays of surrounding iron are generated in addition to X-rays of Mn and S, and the quantification result is FeMnS
Is misrecognized as a compound of The online automatic particle analysis that is being developed is a function that classifies compounds by quantitatively analyzing all inclusions (particles) recognized in the electronic image. At this time, small MnS particles are present in steel as described above. If it is included, it is grouped as a compound FeMnS different from MnS, and there is a problem that it is determined that more compounds exist than actually. This is also because the compound grouping is constructed mainly by weight concentration.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the conventional particle analyzer, and it is possible to correctly determine a compound to be analyzed even in the case of particles having a size smaller than the electron diffusion region of a sample irradiation electron beam. It is an object of the present invention to provide a particle analyzer using EPMA.

[0007]

In order to solve the above problems, the present invention provides an electron probe which irradiates a sample with an electron beam and performs elemental analysis of the sample surface based on characteristic X-rays emitted from the sample. In the microanalyzer, means for observing the sample surface as an electron image, means for calculating the position of the center of gravity of the particles on the observed sample surface, and moving the sample stage or the electron beam to fix the electron beam at the position of the center of gravity of the particles Means for controlling, means for quantitatively analyzing the elements of the particles, means for calculating the atomic ratio from the element weight concentration based on the quantitative analysis result, and grouping by performing compound determination based on the calculated atomic ratio The counting means constitutes a particle analysis device.

As described above, the compound is determined based on the atomic ratio calculated based on the weight concentration of the element obtained as a result of the quantification. It becomes possible to determine the compounds of the same group even if the particle size becomes small or the concentration becomes small, and accurate particle analysis can be performed without erroneous recognition.

[0009]

Next, an embodiment will be described. FIG. 1 is a schematic configuration diagram showing an embodiment of a particle analysis device using EPMA according to the present invention. In FIG.
1 is an electron gun, 2 is a condenser lens coil, 3 is an objective aperture, 4 is a Faraday cup, 5 is a scanning (deflection) coil,
6 is an astigmatism correction coil, 7 is an objective lens, 8 is a backscattered electron detector, 9 is a secondary electron detector, 10 is a sample, 11 is a sample stage, and 12 is a stage drive motor. Reference numeral 13 denotes an X-ray spectroscopy element, 14 denotes an X-ray detector, 15 denotes an X-ray spectroscopy element driving motor, and these constitute a WDS (Wavelength Dispersion X-ray Spectrometer) 16. 17 is an EDS (energy dispersive X-ray spectrometer), 18 is an optical microscope, 19 is an EDSX signal data acquisition device, 20 is an electronic scanning circuit, 21 is a secondary electron signal data acquisition device, 22 is a reflected electron signal data acquisition. Device, 23 is a stage motor control circuit, 24 is a WDS X-ray signal data acquisition device, 25 is a central processing unit, 26 is a mass storage device, and in the central processing unit 25, secondary electron signal data or reflected electron signal data is used. Means 27 for calculating the center of gravity of the particles in the sample based on the sample electron image, EDSX-ray signal data or WDS
A means for calculating the atomic ratio of the particle constituents from the result of the quantitative analysis performed based on the X-ray signal data; and a means for determining the compounds based on the atomic ratio, grouping the groups, and totalizing the results. I have.

Next, the operation of the particle analyzer thus constructed will be described. First, electron beam scanning through the electronic scanning circuit 20 and the scanning coil 5 or scanning of the sample stage 11 through the stage motor control circuit 23 and the stage motor 12 is performed, and reflected electrons or secondary electrons from the sample surface are scanned. Is detected by the reflected electron detector 8 or the secondary electron detector 9, and a reflected electron image or a secondary electron image of the sample surface is obtained via the reflected electron signal data acquisition device 22 or the secondary electron signal data acquisition device 21. .

Then, the center of gravity of each particle in the sample is calculated based on the reflected electron image or the secondary electron image of the sample surface.
27, the electron beam is fixed by sequentially moving the sample stage 11 or the electron beam to the position of the center of gravity of each particle, and
Perform quantitative analysis by S16 or EDS17. And WDS
The analysis result is stored in the mass storage device 26 via the X-ray signal data acquisition device 24 or the EDSX-ray signal data acquisition device 19. In this quantitative analysis, all the detected elements are quantitatively analyzed, or only the element of interest in the detected elements is selected and quantitative analysis is performed. Next, the atomic ratio of the particle constituting material is calculated using the atomic weight based on the element weight concentration% obtained from the quantitative analysis result in the atomic ratio calculating means 28, and the compound Judgment is performed, grouping and aggregation are performed, and the particle analysis of the sample is completed.

As described above, by calculating the atomic ratio and determining the compound based on the calculated atomic ratio, the target compound can be correctly determined even in the case of small particles smaller than the electron diffusion region of the electron beam. it can. For example, MnS in steel
In the case of analyzing MgO particles and MgO particles, when a compound is determined at the conventional weight concentration, for example, 57 MnS, Fe _X (M
nS) _1-X: 23 pieces, MgO: 35 _{pieces, Fe X (MgO) 1-} X: Even when 17 and will be determined, according to the present invention, MnS: 80
And MgO: 52 can be correctly determined. Also,
Even if the sample surface is slightly contaminated and the quantitative element concentration decreases,
Since the compound is determined by the atomic ratio, correct particle analysis is possible.Also, even if the sample surface has some irregularities and the X-ray intensity decreases and the quantitative element concentration decreases, the compound is determined by the atomic ratio. Therefore, the analysis can be performed by offsetting the decrease in X-ray intensity, and even if the particle shape is somewhat complicated and the center of gravity is shifted outside the particle, the target compound can be analyzed if the particle is included in the electron diffusion region. Analysis is possible.

[0013]

As described above with reference to the embodiments, according to the present invention, a compound is determined based on an atomic ratio obtained from a quantitative analysis result, so that a sample is irradiated. Even in the case of small particles smaller than the electron diffusion region of the electron beam, it is possible to correctly determine the target compound, and the small particles are analyzed and E
A particle analysis device using PMA can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a particle analysis device based on EPMA according to the present invention.

FIG. 2 is a diagram showing a sample surface in which MnS and MgO particles are present in steel.

[Explanation of symbols]

 Reference Signs List 1 electron gun 2 condenser lens coil 3 objective aperture 4 Faraday cup 5 scanning (deflection) coil 6 astigmatism correction coil 7 objective lens 8 backscattered electron detector 9 secondary electron detector 10 sample 11 sample stage 12 stage drive motor 13 X-ray Spectroscopic element 14 X-ray detector 15 Motor for driving X-ray spectroscopic element 16 WDS 17 EDS 18 Optical microscope 19 EDSX X-ray signal data acquisition device 20 Electronic scanning circuit 21 Secondary electron signal data acquisition device 22 Reflected electron signal data acquisition device 23 Stage Motor control circuit 24 WDS X-ray signal data acquisition unit 25 Central processing unit 26 Mass storage unit 27 Center of gravity calculation unit 28 Atomic ratio calculation unit 29 Compound grouping and aggregation unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yu Takakura 3-1-2 Musashino, Akishima-shi, Tokyo Japan Electronic Co., Ltd. (72) Hidemi Ohashi 3-1-2 Musashino, Akishima-shi, Tokyo Japan Electronics F term in the company (reference) 2G001 AA03 BA05 BA07 BA15 BA30 CA01 CA03 CA10 EA01 EA03 EA08 FA06 FA18 HA09 JA11 KA01 KA20 MA04 NA03 NA08 NA10 NA17 NA20 PA11 5C033 PP01 PP02 PP05 PP06

Claims (1)

[Claims] An electron probe microanalyzer for irradiating a sample with an electron beam and performing elemental analysis of the sample surface based on characteristic X-rays emitted from the sample, means for observing the sample surface as an electronic image, Means for calculating the position of the center of gravity of the particles on the surface of the sample, means for moving the sample stage or the electron beam to fix and control the electron beam at the position of the center of gravity of the particles, and means for quantitatively analyzing the elements of the particles, A particle analysis device comprising: means for calculating an atomic ratio from the elemental weight concentration based on the result of quantitative analysis; and means for determining a compound based on the calculated atomic ratio and grouping and totaling. .