JPS62285048A - Element density distribution measurement - Google Patents

Abstract

PURPOSE:To obtain a correct element density distribution data, by removing the intensity of a background generated from an element to be measured from the intensity of an X-ray detection signal with a characteristic X-ray wavelength of the element being measured. CONSTITUTION:A charged particle beam E excites a sample S to release electron beam and X rays. An X rays spectroscope 1 has a mechanism, which can drive a driving section 5 with a drive controller 6 to scan wavelength, and spectrally analyzes X rays released from the sample S. An X rays detector 2 detects the X rays analyzed with the X rays spectroscope 1. Then, a signal processor 3 counts and store detection pulses detected with the X rays detector 2 and a sample stage 7 moves the sample S with a driver 8 to scan the surface of the sample by an electron beam. Then, at measuring points on the surface of the sample, the X rays spectroscope is used to measure the intensity BG of a background and the peak intensity PK of characteristic X-ray to be stored into a memory. A CPU calculates a difference I=[PK-BG] to record 9 and display 10 various data thus obtained.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention A. Field of Industrial Application The present invention is directed to the detection of characteristic X-rays generated by a sample such as EPMA by exciting the sample with a charged particle beam or the like. This article relates to a method for determining the elemental concentration distribution of a sample.

Conventional technology EPMA and other devices excite the sample with charged particles, etc., detect the characteristic X-rays generated by the sample, and obtain the elemental concentration distribution of the sample.One-plane line analysis is performed as a concentration distribution analysis. In conventional methods, an X-ray spectrometer was tuned to the wavelength of the characteristic X-ray of the target element, scanned the sample surface, detected only the peak intensity of the characteristic X-ray signal, and displayed this as concentration indication data of the target element. ing. However, if the composition or morphology of the sample changes significantly depending on the part of the sample, the background intensity of If the element concentration is displayed as it is, there is a problem in that the change in the background is relatively large and the result is displayed differently from the actual concentration distribution. For this reason, it is not only possible to make a quantitative judgment, but even if the target element appears on a chart or in an X-ray image of the sample surface, it is sometimes unclear whether or not the element truly exists. There are many.

This is because there is a possibility that X-ray intensity (background intensity) other than the characteristic X-rays generated from the measured element is being detected. Therefore, analysis is extremely difficult, especially when only data from line analysis or surface analysis is shown alone.

Problems to be Solved by the Invention The present invention removes 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. The purpose is to provide accurate elemental concentration distribution data.

21. Means for solving the problem Using a device that scans and excites the sample with charged particles, etc., and spectroscopy the X-rays generated from the sample, the characteristic X-rays corresponding to the element to be measured and the peaks of the same characteristic X-rays are used. X-ray intensity measurement data for both X-rays with wavelengths slightly apart from the rising edge of the sample were obtained in the scanning range of the sample surface, and the difference between the measured values was calculated and displayed as the element concentration.

According to the present invention, the background intensity BG and the characteristic X-ray vinyl intensity PK are measured using an X-ray spectrometer at each measurement point on the sample surface and stored in the memory, as shown in FIG. and the CPU calculates the difference I-[PK BG ]. For example, as shown in Figure 3a, there are three measurement areas, A and B.

In this case, the background intensity in each phase is as shown in Figure 3, and the actual concentration distribution of the target element is as shown in Figure 3d. Whereas C in FIG. 3, which is a superimposition of C and d, is displayed as the concentration distribution, in the present invention, a shape obtained by subtracting C from FIG. 3 is displayed, so that a correct concentration display can be obtained.

Embodiment FIG. 1 shows an embodiment of the present invention. In Figure 1, S
1 is a sample; E is a charged particle beam that excites the sample S to emit electron beams and The X-rays emitted from the sample S are spectrally analyzed. The X-ray detector 2 detects the X-rays separated by the X-ray spectrometer 1. 3
is a signal processing device that counts and stores detection pulses detected by the X-ray detector 2; 4 is a CPU that performs the processing shown in the flowchart of FIG. Reference numeral 7 denotes a sample stage in which the sample S is moved by a drive device 8 and the sample surface is scanned by 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 with the above configuration will be explained with reference to the flowchart shown in FIG. Since surface analysis can be performed by repeatedly performing line analysis by shifting the scanning line one pitch at a time, we will explain the case of line analysis. First, set the sample at one measurement point (b), and drive the drive unit 5 of the X-ray spectrometer 1 at that measurement point by sending a drive signal from the drive control device 6. The peak value P of the characteristic X-ray as shown in Fig. 2 is obtained by scanning the two designated wavelength points shown in Fig.
Measure K and the background value Be at a wavelength position slightly apart from the rise of the peak, and store the position and detected value (see below). The true concentration I is calculated by subtracting the background value BG from the stored peak value P of the characteristic X-ray and is stored (c). The stage 7 is driven by the drive device 8 and the sample S is set at the next measurement point (a). When the measurement is completed, the concentration ■ stored in the CPU 4 is displayed on the display W10.

In this example, wavelength scanning is performed with a scanning spectrometer at all measurement points to measure the peak value P of characteristic X-rays and the background value Be, but before measurement, the X-ray image is observed. Divide the same compositional region (phase), specify one or more measurement points for each phase, measure the background value Bo at the specified measurement point, memorize the measured value, and recalculate the characteristic X-ray. The same effect can be obtained by measuring the peak value pg over the entire measurement range and subtracting the background value Ba of that phase for each phase to determine the true concentration.

In addition, using two spectrometers, one is set to the characteristic X-ray wavelength of the element to be measured and measures the peak value PK of the characteristic The same effect can be obtained by setting the wavelength at the wavelength point, measuring the background value Bo, and simultaneously detecting the peak value PK of the characteristic X-ray and the background value BG.

Alternatively, scan the sample surface at the peak wavelength position of the characteristic X-ray to detect the peak value PK, and then scan the sample surface at a wavelength position away from the peak wavelength position of the characteristic X-ray to detect the background value BG. However, the same effect can be obtained by storing each data in memory and subtracting it later to find the true density.

G. Effects According to the present invention, since accurate concentration analysis data is displayed, it becomes easy to analyze the records of analysis results, and the accuracy of analysis is further improved.

[Brief explanation of the drawing]

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 at each phase when line analysis is performed, and Fig. 4 The figure is a flowchart diagram of the CPU. S: Sample, E: Charged particle beam. 1...X-ray spectrometer, 2...X-ray detector. 3...Signal processing device, 4...CPU. 5... Drive unit, 6... Drive control device. 7... Stage, 8... Drive device. 9...Recording device, 10...Display device.

Claims (1)

[Claims] Using a device that scans and excites a sample with charged particles, etc., and spectroscopy the X-rays generated by the sample, it is able to detect characteristic X-rays corresponding to the element to be measured and X-rays at a wavelength slightly apart from the rise of the peak of the same characteristic X-rays. 1. A method for measuring element concentration distribution, characterized in that X-ray intensity measurement data for both lines are obtained in a scanning range of a sample surface, and the difference between the measured values is calculated and displayed as an element concentration.