JPH0785064B2 - Element concentration distribution measurement method - Google Patents

Description

Detailed Description of the Invention a. Industrial field of the present invention, such as EPMA, by exciting the sample with a charged particle beam,
The present invention relates to a method of detecting a characteristic X-ray generated from a sample and obtaining an element concentration distribution of the sample.

B. Conventional techniques such as EPMA, where the sample is excited by charged particles and the characteristic X-rays generated from the sample are detected to obtain the elemental concentration distribution of the sample, when performing line analysis or area analysis as concentration distribution analysis, Conventionally, the X-ray spectroscope is adjusted to the wavelength of the characteristic X-ray of the target element, the sample surface is scanned, only the peak intensity of the characteristic X-ray signal is detected, and this is displayed as concentration instruction data of the target element. . However, when the composition or morphology of the sample changes significantly depending on the site of the sample, the background intensity of X-rays differs depending on the place of the sample, and when the target element concentration is low or the concentration change is minute, the detected signal intensity When is directly displayed as the elemental concentration, there is a problem that the background changes relatively large and the result different from the actual concentration distribution is displayed. For this reason, if the target element is displayed on the X-ray image on the chart or on the sample surface, not only the quantitative judgment but also the judgment as to whether the element really exists or not is ambiguous. There are many. This is because there is a possibility that the X-ray intensity (background intensity) other than the characteristic X-ray generated from the measurement element may be detected. Therefore, when only the data of these line analysis and area analysis are shown alone, the analysis is very difficult.

C. Problems to be Solved by the Invention The present invention eliminates X-ray intensity (background intensity) other than the characteristic X-rays generated from the measurement element from the X-ray detection signal intensity of the characteristic X-ray wavelength of the measurement element, and The purpose is to be able to provide various element concentration distribution data.

D. Means for Solving Problems Using a device that scans and excites a sample with charged particles and separates the X-ray generated from the sample with an X-ray spectrometer using a dispersive crystal, the entire analysis area of the sample surface is scanned in advance. Then, an X-ray image is taken, and the analysis region is divided by the same composition region, that is, the phase by the image, and at a wavelength in the background region close to the characteristic X-ray peak wavelength of the quantitative target element at one to several points for each phase. The background X-ray intensity is measured and stored, and then the entire analysis area of the sample is scanned to perform the characteristic X-ray intensity measurement, and the background intensity previously measured for each phase is subtracted. Then, it is displayed as the concentration of the target element.

E. Action According to the present invention, the background intensity is measured by the X-ray spectroscope at each measurement point on the sample surface, as shown in FIG.
B _G and the peak intensity P _K of the characteristic X-ray are measured and stored in a memory, and the CPU calculates the difference I = [P _K −B _G ]. For example, as shown in FIG.
3b, the background intensity in each phase is as shown in FIG. 3b, and the actual concentration distribution of the target element is as shown in FIG. 3d. In contrast to the density distribution shown in FIG. 3c in the form of overlapping FIGS. 3b and 3d, the present invention displays the density subtracted from FIG. Here, in the present invention, the background intensity data is obtained by measuring a small number of points for each phase of the sample surface rather than measuring the entire analysis area of the sample surface at the background wavelength. In comparison with measuring the characteristic X-ray and the background for each pixel of the sample surface, the time required for the measurement is shortened.

F. Embodiment FIG. 1 shows an embodiment of the present invention. In FIG. 1, S
Is a sample, E is a charged particle beam that excites the sample S to emit an electron beam and X-rays, 1 is an X-ray spectroscope, and a drive controller 5 drives a drive unit 5 to provide a mechanism for wavelength scanning. X-rays emitted from the sample S are separated. The X-ray detector 2 detects the X-rays dispersed by the X-ray spectroscope 1. Three
Is a signal processing device that counts and stores the detection pulses detected by the X-ray detector 2. A CPU 4 executes the processing shown in the flowchart of FIG. A sample stage 7 moves the sample S by a driving device 8 to scan the sample surface with an electron beam. A recording device 9 records various data obtained by the CPU 4. A display device 10 displays various data obtained by the CPU 4.

The operation of the CPU 4 having the above configuration will be described with reference to the flowchart of FIG. Since the surface analysis can be performed by repeating the line analysis by shifting the scanning lines by one pitch, the case of the line analysis will be described. First, the spectroscope is aligned with one wavelength position, and the entire analysis region of the sample is scanned with an electron beam to collect X-ray intensity data (a). The wavelength set here is arbitrary, but it is preferable to set the wavelength at which strong X-rays are radiated, for example, the characteristic X-ray wavelength of the main component (element contained in the largest amount) in the sample. Image display of the next collected data (b)
To do. This image is used to identify the phase on the sample surface, the phase boundary data is input to the signal processing device together with the phase identification code (c), the measurement point is specified for each phase, and the spectroscope is set to the background wavelength. Set and start the measurement, and store the measurement data for each point (D). When the measurement of all designated points is completed, the spectral wavelength is adjusted to the characteristic X-ray wavelength of the element to be quantified, the analysis of the entire analysis region is started, and the measurement data is stored (e). After this measurement, the background intensity data stored in step (d) for the corresponding phase is subtracted from the X-ray intensity data obtained in step (e) to convert it to the concentration value I of the target element. Then, the display device 10 records or displays (f), and the operation ends. When subtracting the background of the corresponding phase from the data of the step (e), the boundary calculation data of the phase and the phase identification code are used, and the above calculation is performed using them.

G. Effect According to the present invention, the result of background correction is obtained by line analysis or surface analysis of the sample surface by X-ray spectroscopy.
The analysis of the record of the analysis result becomes easy, the analysis accuracy is improved, and the characteristic X-ray measurement of the target element and the background measurement are performed for the entire analysis region, or the characteristic X-ray wavelength is measured for each pixel. X to background wavelength
Compared to moving the line spectroscope, the number of background measurement points is smaller, the time required for analysis is shorter, and the driving amount of the X-ray spectroscope is also reduced, which is advantageous in maintenance of the spectroscope.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a signal intensity diagram obtained by wavelength-scanning a measurement point, FIG. 3 is a signal diagram in each phase when line analysis is performed, and FIG. The figure is a flow chart of the CPU. S ... Sample, E ... Charged particle beam, 1 ... X-ray spectrometer, 2 ... X-ray detector, 3 ... Signal processor, 4 ... CPU, 5 ... Driving unit, 6 ... Driving Controller, 7 ... Stage, 8 ... Driving device, 9 ... Recording device, 10 ... Display device.

Claims (1)

[Claims] 1. An X-ray having an appropriate wavelength is preliminarily scanned by scanning an entire analysis area of a sample surface by using an apparatus for scanning and exciting the sample with charged particles or the like and dispersing X-rays generated from the sample using a dispersive crystal.
A line image is taken, and the analysis area of the sample is divided into phases according to the image, and one to several points are specified for each phase, and the background is at a wavelength in the background region close to the characteristic X-ray wavelength of the quantitative target element. The intensity is measured and stored, and then the entire analysis area of the sample is scanned to measure the intensity of the characteristic X-ray,
A method for measuring element concentration distribution, characterized in that the background intensity measured in advance for each phase is subtracted from the data and recorded or displayed as the concentration of the target element.