JP2564896B2 - X-ray spectroscopic mapping device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus for measuring element distribution on a sample surface by X-ray spectroscopy.

(Prior Art) A sample surface mapping analysis is performed in which the element distribution on the sample surface is measured by X-ray spectroscopy using an electron microanalyzer, and the element concentrations are color-coded and visually displayed. In this case, one X-ray spectroscope is used for one element, and the sample surface is scanned in accordance with the wavelength of one characteristic X-ray of one element to be measured by the X-ray spectroscope. On the other hand, when one site of the sample surface is irradiated with an excitation ray and the spectrum of the X-rays emitted from the sample is measured, the characteristic X-ray peaks of the constituent elements of the sample are found to be the device characteristic, the sample excitation condition and the sample. You can see that you are riding on the background determined by the composition. However, as described above, since the mapping measurement was conventionally performed by the one element one X-ray spectroscope, the background correction cannot be performed in real time, and the background measurement is performed over the entire sample surface before or after the fact. A method has been used in which background correction is performed, or background measurement is performed at several points on the sample surface to estimate the background of the entire sample surface for correction. In the former method of performing background measurement over the entire sample surface, the sample surface is scanned twice, so the overall analysis time becomes very long, and in the latter several points the background measurement method is Although not very disadvantageous in terms of time, accurate background correction cannot be performed because the background is affected not only by the device characteristics and sample excitation conditions, but also by the elemental composition at the measurement point.

(Problem to be Solved by the Invention) The present invention is to provide an X-ray spectroscopic mapping device capable of accurately performing background correction without increasing the time required for analysis as a whole.

(Means for Solving the Problem) A plurality of X-ray spectroscopes are used for one element, and the focal positions on the sample surface of the X-ray spectroscopes are made to coincide with each other, and one X-ray spectroscope is to be measured. Matching to one characteristic X-ray wavelength of the element, the other X-ray spectroscope is adjusted to the wavelength corresponding to the skirt of the characteristic X-ray peak of the element to be measured close to the above wavelength, and the above X-ray spectroscopes simultaneously The sample surface was scanned to obtain the characteristic X-ray data including the background of the element to be measured and the background data at the same time to perform the background correction.

(Operation) When the X-ray spectrum before and after the characteristic X-ray peak of one of the elements to be measured is measured, it is generally as shown in FIG. In this figure, P is the characteristic X-ray peak of the element to be measured, and B is the background. In the present invention, one of the plurality of X-ray spectroscopes is divided into the central wavelength λo of the characteristic X-ray peak, and the wavelength of the other X-ray spectroscope is adjusted to λ or λ'in the figure. In this way, the characteristic X-ray data and the background correction data are simultaneously obtained by simultaneously scanning the sample surface while observing the same point on the sample surface with a plurality of X-ray spectroscopes, so that the background correction is performed in real time. Since the background correction data is obtained over the entire measurement area of the sample, the background correction can be accurately performed without being affected by the element distribution.

(Embodiment) FIG. 1 shows an apparatus according to an embodiment of the present invention. The main part of the device of the embodiment is EPMA, and this kind of device is generally 2-6.
An X-ray spectroscope on the stage is arranged around an electron optics unit that forms an electron beam that illuminates the sample. In this embodiment, two of the plurality of X-ray spectroscopes correspond to the analysis of one element, and the device portion for that one element is shown in the drawing. In the figure, e is an electron beam, S is a sample, and 1 is a sample.
The sample stage is moved in two directions.

Reference numerals 2 and 3 are X-ray spectroscopes, and each X-ray spectroscope includes curved crystals C and C'for spectroscopic analysis, X-ray detectors 4 and 5, an electron beam irradiation point on the sample S, and each spectroscopic crystal. A mechanism for connecting the dispersive crystal and the X-ray detector so that C, C'and the front slits of the X-ray detectors 4 and 5 are positioned on the circumference of each Roland circle for each of the spectroscopes 2 and 3. Both X-ray spectroscopes 2 and 3 are arranged such that the electron beam irradiation point on the sample becomes a common focus of both X-ray spectroscopes 2 and 3. 6 is an X-ray detector
A data writing unit for A / D converting the outputs of 4 and 5 and storing them in the image memories 7 and 8 together with the position information of the sample. Reference numeral 9 is a sample stage driving device, which is a pulse for driving the sample stage in the x direction and the y direction. It has a motor. The pulses that drive these pulse motors are given from the central processing unit CPU,
Those pulse signals are also input to the data writing section as information on the position of the sample S. Reference numeral 10 is a background correction calculation unit, and the background-corrected element mapping data of the sample surface is stored in the image memory 11. A spectroscope driving device 12 is provided at the wavelength position set by the wavelength setting means 13 and has the dispersive crystals C1 and C2 and the X-ray detectors 4,5.
To move. Image memory 11 contents are color CRT14
Are displayed in color by.

In the above-mentioned configuration, the spectroscope 2 is set to the wavelength position of the appropriate characteristic X-ray of one element to be analyzed, and the spectroscope 3 is set to the wavelength value located at the skirt of the characteristic X-ray peak close to the above wavelength. Set. These two wavelengths are designated by the wavelength setting means 13. For this wavelength setting, the X-ray spectrum (Fig. 2) obtained by scanning the spectroscope 2 at an arbitrary point with an appropriate range centered on the wavelength of the characteristic X-ray of the target element on the CRT14 Displayed on the second
The wavelengths of λo and λ are determined. When the mapping operation is started after setting the wavelengths of the two X-ray spectrometers 2 and 3, CP
U controls the sample stage 9 to drive the sample S in the x and y directions to scan the sample surface with the electron beam e, and the detector 4
The output of the detector is stored in the image memory 7, and the output of the detector 5 is stored in the image memory 8. At this time, the data writing unit 6 counts the drive pulses in the x direction and the y direction input to the sample stage drive device 9 to obtain information on the position of the electron beam irradiation point on the sample, and based on this information, the image memory 7 , 8 address information is formed and the outputs of the X-ray detectors 4 and 5 are stored in the respective image memories. After scanning the sample surface
The CPU causes the background correction calculation unit 10 to perform background correction on the characteristic X-ray detection output data of the target element stored in the image memory 7, and the result is stored in the image memory 11 at the same address as the image memories 7 and 8. It is stored using information, and the contents of the memory are displayed on the CRT 14 as a concentration distribution pattern of the target element on the sample surface in response to an external command.

The background correction calculation performed by the background correction calculation unit 10 is performed as follows in this embodiment. The data stored in the image memory 8 is the X-ray detection output at the wavelength λ shown in FIG. 2, which is the X-ray intensity at the tail of the characteristic X-ray peak of the target element and indicates the intensity of the background. . However, since this data is highly uneven due to statistical fluctuations during X-ray detection, the calculation unit 10
Then, the data in the image memory 8 is once read out, the smoothing process is performed, the smoothed background data is stored in the image memory 8 again, and then the data at the same address is read from the image memories 7 and 8, and the data in the image memory 7 is read. The result of subtracting the data of 8 to 8 is stored in the same address of the image memory. In this way, the background-corrected mapping data of the target element is stored in the image memory 11.

(Effect of the Invention) According to the present invention, in the mapping measurement of the element distribution on the sample surface, the background correction data is simultaneously collected during the mapping operation, and the background correction data at the same point as the analysis point is obtained over the entire surface of the sample. Therefore, accurate background correction is possible without increasing the overall analysis time.

[Brief description of drawings]

FIG. 1 is a block diagram of a main part of an apparatus according to an embodiment of the present invention.
The figure shows the X-ray spectrum near the peak of one characteristic X-ray. 1 ... Sample stage, 2,3 ... X-ray spectroscope, 4,5 ... X-ray detector, 6 ... Data writing section, 7,8,11 ... Image memory, 9 ... Sample stage drive device , 10 …… Background correction calculation unit, 12 …… Spectrometer drive device, CPU …… Central processing unit.

Claims (1)

(57) [Claims] 1. A plurality of X-ray spectroscopes are arranged around the sample such that their focal points coincide with each other on the sample surface, and the detection wavelength of one of the X-ray spectroscopes is set to an appropriate characteristic X-ray wavelength of the target element. In addition, the detection wavelength of the other X-ray spectroscope is adjusted to the wavelength of the tail of the characteristic X-ray on the X-ray spectrum of the sample, and the X-ray detection output of the angular X-ray spectroscope at the same time is taken in to obtain the sample. X-ray spectral mapping, characterized in that background correction calculation means for performing a correction calculation using the output of the other X-ray spectroscope for the output of the one X-ray spectroscope for the same point above is provided. apparatus.