JPS627974B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray analyzer, and more particularly, to an X-ray analyzer that can analyze the composition of a sample by projecting a finely focused electron beam onto the sample and measuring the wavelength and intensity of the X-rays generated from the sample. The present invention relates to a so-called X-ray microanalyzer that performs.

One of the analytical methods conventionally performed using this type of apparatus is a method called area analysis. In other words, an electron beam is scanned two-dimensionally over a sample, and among the X-rays sequentially generated from the sample, the X-rays with wavelengths corresponding to the sample components to be analyzed are selectively extracted through a spectroscopic system. By introducing it into an X-ray detector and converting it into an electrical signal corresponding to the X-ray intensity, and further supplying the signal as a luminance signal to a cathode ray tube that is scanned in synchronization with the electron beam scanning on the sample. A characteristic X-ray image corresponding to the concentration distribution of the sample component to be analyzed can be obtained on the cathode ray tube screen.

However, with this method, the range that can be analyzed in one scan is extremely narrow due to limitations imposed by the X-ray spectroscopic system, and in the case of large samples, the area analysis must be repeated by moving the sample in small increments. It has the disadvantage that it cannot be used. In other words, the electron beam projection point on the sample, the X-ray spectrometer crystal, and the X-ray detector have a predetermined positional relationship (determined according to the wavelength of the X-ray to be selected) on a predetermined circle (Rowland circle). However, if the electron beam is scanned along the plane containing the Rowland circle, the angle of incidence of the X-rays on the spectroscopic crystal will change as the electron beam scans, and the wavelength of the resulting spectroscopic X-rays will be Produces a different result than the preset one. Therefore, the scanning range of the electron beam must be kept within a range that allows the above-mentioned errors (usually several hundred μm). Incidentally, if the electron beam is scanned in a direction perpendicular to the plane containing the Rowland circle, there is little risk of the above error occurring, but the scanning range in this direction is usually limited by the size of the spectroscopic crystal. It is about 1 mm to several mm.

The present invention has been made in view of the above-mentioned points, and it is an object of the present invention to provide an X-ray analyzer that can perform area analysis over a wide range in one scan. The present invention will be explained in detail below based on the drawings.

FIG. 1 is a diagram for explaining one embodiment of the present invention, and in the figure, reference numeral 1 denotes an electron beam narrowly focused by an electron optical system (not shown). The electron beam 1 is two-dimensionally scanned over a sample 4 by deflection coils 3X and 3Y to which a scanning signal from a scanning circuit 2 is supplied. X-rays 5 generated from the sample by electron beam scanning are incident on a spectroscopic crystal 6 curved along a predetermined Rowland circle. The X-rays separated by the spectroscopic crystal 6 are detected by the X-ray detector 7. The detection signal obtained from the detector 7 is sent to an amplifier 8.
The brightness signal is sent to the grid of the cathode ray tube 9 as a brightness signal. A scanning signal from the scanning circuit 2 is supplied to the deflection coil 10 of the cathode ray tube 9.
Reference numeral 11 detects the electron beam position on the sample based on the scanning signal generated by the scanning circuit 2, and supplies it to the spectroscopic crystal moving mechanism 12 to move the spectroscopic crystal along the Roland circle according to the electron beam position. This is a control circuit for generating position signals.

In the above configuration, the control circuit 11 determines the scanning position of the electron beam based on the scanning signal from the scanning circuit 2, and selects a desired wavelength of the X-rays generated from the electron beam projection point on the sample according to the determined position. A position signal is sent to the moving mechanism 12 to change the position of the spectroscopic crystal 6 along the Rowland circle so that only the X-rays enter the detector 7. For example, when the X-direction scanning of the electron beam on the sample is approximately perpendicular to the plane containing the Rowland circle, the spectroscopic crystal 6, the sample 4, and the detector 7 seen from above in FIG. This will be explained using FIG. 2 showing the arrangement.

In Fig. 2, when the spectroscopic crystal is at position 6A, the detection range Z in which X-rays of a predetermined wavelength on the sample 4 can be effectively detected is 1 mm to several mm in the direction perpendicular to the plane containing the Rowland circle, as mentioned earlier. mm, and a rectangle with a length of several hundred μm in the direction along the plane that includes the Rowland circle. The detection range Z moves from position ZA to position ZB on the sample as the spectroscopic crystal moves along the Rowland circle from position 6A to position 6B. Therefore, if the spectroscopic crystal is moved from position 6A to position 6B as the electron beam is scanned from A to B on the sample, X of a predetermined wavelength will be transmitted over the entire surface within the electron beam scanning range S. Because lines can be detected, several mm x several
Surface analysis over a wide area of up to mm can be performed with a single electron beam scan without moving the sample.

In the above case, since the X-direction scan of the electron beam is approximately perpendicular to the plane containing the Rowland circle, the surface analysis could be performed simply by moving the spectroscopic crystal from the position 6A to the position 6B. However, it is common practice to place two or more separate spectroscopic systems around the sample to simultaneously detect X-rays with different wavelengths emitted from the same point on the sample. Depending on the spectroscopic system, for example, as shown in FIG. 3, the scanning of the electron beam in the X direction may not be perpendicular to the plane containing the Rowland circle.
Even in such a case, the control circuit determines the X and Y coordinates of the electron beam projection point from the scanning signal, learns the positional change of the electron beam projection point based on the determined coordinates, and determines whether the electron beam projection point is within the detection range. As always, a position signal is generated to move the spectroscopic crystal along the Rowland circle. In other words, when the electron beam is scanned from point C to point D on the sample, the detection range covers it and extends from ZC to point D.
The spectroscopic crystal is moved along the Rowland circle from 6C to 6D so as to move to ZD. Similarly, the spectroscopic crystal repeats reciprocating movement following the electron beam scanning, and when the electron beam scan ends at point E, the spectroscopic crystal has reached position 6E to place the detection range at position ZE.

As described in detail above, according to the present invention, by moving the spectroscopic crystal in response to electron beam scanning, surface analysis over a wide area can be performed without moving the sample.

In the above-described embodiments, the case where the electron beam is scanned only in one direction has been described, but it goes without saying that the present invention is not limited to this, and can also be applied to a case where the electron beam is scanned alternately in opposite directions (reciprocating scanning).

[Brief explanation of the drawing]

FIG. 1 is a partial configuration diagram showing one embodiment of the present invention, and FIGS. 2 and 3 are diagrams for explaining the operation of the embodiment shown in FIG. 1. 2: Scanning circuit, 3X, 3Y: Deflection coil, 4:
Sample, 5: X-ray, 6: Spectroscopic crystal, 7: X-ray detector, 9: Cathode ray tube, 11: Control circuit, 12: Spectroscopic crystal movement mechanism.

Claims (1)

[Claims] 1. A means for projecting a narrowly focused electron beam onto a sample, a deflector for deflecting the electron beam, and a scanning signal for two-dimensionally scanning the electron beam on the sample to the deflector. an X-ray spectrometer into which the X-rays generated from the sample are incident, an X-ray detector into which the X-rays separated by the X-ray spectrometer are introduced, and the X-ray spectrometer is arranged in a Roland circle. In the apparatus, the moving means is controlled based on an information signal representing the scanning signal, and the position of the X-ray spectrometer is adjusted according to the irradiation position of the electron beam on the sample. An X-ray analysis device characterized by being provided with a control means for changing.