JPH01307148A - X-ray spectral analyzing device - Google Patents

Abstract

PURPOSE:To move a specimen surface to the proper position by a single action by moving the specimen in such a direction as to provide equal output from two X-ray spectrum analyzers, arranged on the optical axis of an electron optical system with the point of view dislocated, while comparing the outputs from these two spectral analyzers. CONSTITUTION:In an X-ray spectral analyzer to locate a pointlike X-ray source on a Rowland circle by the use of bent crystals for spectral analysis, two X-ray spectrum analyzers M1, M2 are arranged around the electron beam while the point of view is dislocated in the optical axis (e) direction onto the optical axis (e) of an electron optical system E, i.e., the center line of an electron beam irradiating a specimen S. The point of view O of X-ray spectral analyzer M3 for analyzing specimen is located just in the middle between the points of view A, B of the two X-ray spectral analyzers M1, M2, and the specimen S surface is moved to the position in the middle of the points of view A, B of these two analyzers. Thereby the direction in which the specimen is dislocated, can be sensed, and adjustment of specimen position can be made in a single action without trial motion of the specimen.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention focuses an electron beam on a sample surface, like an X-ray spectrometer in an electron beam microanalyzer (EPMA), and detects X-rays emitted from the sample surface. The present invention relates to a sample position adjustment device in an X-ray spectrometer that uses a curved crystal to perform spectroscopy.

(Prior art) X'! using a curved crystal! In an 1A spectrometer, it is generally necessary to regulate the positional relationship between the three, such that the X-ray entrance slit, the exit slit, and the center of the spectroscopic crystal are located on one Rowland circle. When converging an electron beam on a point on the sample surface and using the convergence point of the electron beam as an X-ray source, the X-ray source can be positioned on the Rowland circle to eliminate the entrance slit. In this case, it is necessary to position the sample so that the electron beam irradiation point of the sample is located at a predetermined position of the X-ray spectrometer, that is, on the Rowland circle.

For this reason, in EPMA, the focal position of the optical microscope, which is attached coaxially with the electron optical system, is usually aligned with the position of the X-ray source in the X-ray spectrometer, and the sample surface is aligned with the focal position of the optical microscope. The sample position is adjusted with respect to the X-ray spectrometer, but if the sample surface is smooth and there is no visible pattern on the sample surface, the position cannot be adjusted using the microscope. In such cases, conventional methods have been used to detect characteristic elements in the sample, for example, if the sample is steel, X-rays are
The conventional method was to set the wavelength of the line spectrometer and adjust the sample position where the X vA detection intensity was maximized. However, with this method, it is not known in advance whether the position of the sample surface deviates from the correct position, positive or negative.
- It is necessary to move the sample for testing, and it is very inefficient. In particular, when analysis is performed while continuously changing the sample position (in some cases, it is necessary to move the sample up and down to follow the inclination or unevenness of the sample surface, but it is unclear whether the sample surface has shifted to the positive or negative side, so a new analysis is required). The horizontal movement of the sample had to be stopped at each point and the sample had to be moved vertically, making it impossible to perform one-dimensional or two-dimensional continuous analysis of the sample surface.

(Problems to be Solved by the Invention) The present invention attempts to detect the direction of positional deviation of the sample surface with respect to the X-ray spectrometer and to move the sample surface to the correct position in one operation.

(Means for solving the problem) In the 19 spectrometer, which uses a curved crystal for spectroscopy and positions the point-like XM source on the Rowland circle, the correct position of the X-ray source is
Let's call it the viewpoint of a line spectrometer. In the present invention, two X-ray spectrometers are arranged around the electron beam with their viewpoints shifted in the optical axis direction on the center line of the electron beam that irradiates the sample, that is, on the optical axis of the electron optical system, and both X-ray spectrometers are By positioning the viewpoint of the X-ray spectrometer for sample analysis at exactly the midpoint between the viewpoints of the instrument, and comparing the X-ray detection outputs of the two X-ray spectrometers, the sample surface can be determined by Moved the viewpoint to an intermediate position.

(Function) Since the two X-ray spectrometers are arranged with their viewpoints shifted on the optical axis of the electron optical system, the detection x111 of these two X-ray spectrometers! If the wavelength is matched to the characteristic X-ray wavelength of any element in the sample, when the sample surface is moved in the direction of the optical axis of the electron optical system, the output of each X-ray detector will change as shown in Figure 3. However, when the sample surface comes to the viewpoint position of each X-ray spectrometer, the output of that X-ray spectrometer becomes maximum, and when the sample surface is at the intermediate position between the above two viewpoints, the output of both X-ray spectrometers becomes maximum. The outputs will be equal. By comparing the outputs of both X-ray spectrometers and moving the sample in the direction where the outputs of both X-ray spectrometers are equal, the sample surface can be positioned at an intermediate position between the two X-ray spectrometers, allowing sample analysis. The viewpoint of the X-ray spectrometer for use with the X-ray spectrometer is positioned in advance between the viewpoints of the two X-ray spectrometers (this allows the sample to be aligned. In this case, the direction in which the sample surface is moved is the same as that of the two X-ray spectrometers. Since it can be determined by comparing the magnitude of the output and there is no need to perform trial movement, the sample surface can be moved up and down while continuously following the inclination or unevenness of the sample surface.

(Example) FIG. 1 shows an example of the present invention. This example is an EPM
In A, E is an electron optical system, G is an electron gun, L is an objective lens, and e is an optical axis of the electron optical system. Ml and M2 are independent X-ray spectrometers, R1 and R2 are Rowland circles in each spectrometer, C1 and C2 are curved crystals for spectroscopy, A1 and A2 are X-ray exit slits, and DI and D2 are
is an X-ray detector. The spectroscopic crystals C1 and C2 are connected to respective feed screws T1. Each screw Tl, T2 is fixed to the base Bl, B2 of the spectrometer, and the X-ray exit slit A
1. A2 and the corresponding detector D1. D2 is integrated and mechanically connected to spectroscopic crystals C1 and C2. This mechanism is the same as the one normally used and is omitted in the figure. Although it cannot be shown in FIG. 1, there is another X-ray spectrometer on the near side in the figure, which is structurally the same as M1 and M2 described above. FIG. 2 shows the arrangement of these X-ray spectrometers, which are arranged radially around the optical axis e of the electron optical system. M3 is an X-ray spectrometer not shown in FIG. In Figure 1, 0 on the optical axis e of the electron optical system.
The points are the regular viewpoint positions of the above-mentioned royal X-ray spectrometers M1 to M3. X-ray spectrometer M1. The bases Bl, B2 of M2 pass through the above 0 point and are at one point PL, P2 on a line perpendicular to the optical axis e.
The spectrometer M1. The viewpoint of M2 can be moved up and down from the 0 point on the optical axis e. Kl.

K2 can be turned with a cam from outside the main body of the EPMA, and is in contact with protrusions Fl and F2 that protrude downward from the bases Bl and B2. Hl in the spectrometer Ml
is a hit fixed to the EPMA main body, and when the cam 1 is rotated 180 degrees from the figure, the protrusion F1 hits Hl due to the weight of the spectrometer M1, and is separated from the cam 1. At this time, the point of view of the spectrometer M1 is is 0 points. When the cam K1 is placed in the position shown in the figure, the protrusion H1 is pushed to 1 by the cam, and the viewpoint of the spectrometer M1 is positioned at point A in the figure. Spectrometer M2
In F2. H2' is a hit fixed to the EPMA main body, and when the cam 2 is separated from the protrusion F2 as shown in the figure, F2 comes into contact with the hit F2 due to the weight of M2, and at this time, the viewpoint of the spectrometer M2 is B in the figure. Located at the point. Turn the cam 2 approximately 180 degrees from this position and the protrusion F2 will hit I]
2. At this time, the viewpoint of the spectrometer M2 is positioned at the regular position O. A sample S is set on an xyzS axis movement stage ST.

The PM is a pulse motor that moves the sample stage in the vertical direction (Z-axis direction) and is controlled by the controller CPtJ.

When automatically controlling the sample position with the above configuration, the sample is set on the stage ST, the viewpoints of the spectrometers Ml and M2 are set at the 0 point, and the respective detection wavelengths are set to the elements selected for sample position control, such as when the sample is For steel, use X-ray detector D1 to match the characteristic X-rays of iron. Align the vertical position of the sample so that the output of either D2 is maximum, and then output the outputs of Di and D2 to the CPU.
to be memorized. In principle, the outputs of Dl and D2 should be equal at this time, but they usually do not match due to differences in sensitivity of the detectors. Next, the detection wavelengths of the spectrometers M1 and M2 are shifted a certain amount above and below the wavelength of the characteristic X-ray, and the detection outputs of Di and D2, which are shifted to the respective wavelengths, are stored in the CPU as baseline data. The CPU calculates the respective baseline intensities at the characteristic Xn wavelength from the detection outputs of Di and D2 at these two wavelengths, and calculates the ratio of the values subtracted from the detection outputs of Dl and D2 at the characteristic x1111 wavelength position. do. This ratio is the spectrometer M1. The above characteristic X of M2
! This is the detection intensity ratio to III. After completing the above preparations, operate the cams Kl and 2 to assemble the spectrometer M1 as shown in FIG. Move M2's viewpoint to points A and B and start the analysis operation. The analysis operation involves moving the sample horizontally and performing analysis along one line on the sample surface.

Meanwhile, the CPU reads the outputs of the detectors Di and D2, and compares the detection outputs of DI and D2, which have been sensitivity-corrected by subtracting the previously stored baseline data and multiplying the value by the ratio based on the sensitivity difference, Pulse motor P so that the values match
Control M. During this time, the detected intensity of characteristic X-rays of the target element is captured by the spectrometer M3 by the CPU, and is stored in the memory m as analysis data.

In the above operation, the spectrometers Ml and M2 are used to adjust the position of the sample, and M3 is used for sample analysis, but the viewpoints of both Ml and M2 can be placed at the zero point by operating the cams Kl and 2. In this case, both Ml and M2 can be used for sample analysis, and therefore, simultaneous analysis of three elements is also possible in this embodiment. Of course, it goes without saying that M1 and M2 may be used exclusively for sample position control, with their viewpoints fixed at points A and B.

Also, in the above explanation, the preparation operations before starting the analysis are a bit troublesome, but the sensitivity data and baseline data of the two X-ray spectrometers are imported in advance and stored in the CPU (by this, each sample It is possible to save the trouble of measuring the sensitivity ratio of two X-ray spectrometers before each analysis.

(Effects of the Invention) According to the present invention, since the direction of displacement of the sample can be detected, the sample position can be adjusted without trial movement of the sample, and it is possible to continuously follow changes in the sample position. So,
The efficiency of continuous analysis of sample surfaces is significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a side view of one embodiment of the present invention, FIG. 2 is a plan view of the same embodiment, and FIG. 3 is an explanatory diagram of the operation of the present invention. G...electron gun, e...electron optical system optical axis, L...objective lens, S...sample, ST...sample stage, P
M...Pulse motor, A, B, O...Viewpoint of X-ray spectrometer, Ml, M2. M3...X* spectrometer, B1. B2
．． B3... Base of X-ray spectrometer, C1, C2... Spectroscopic crystal, Tl, T2... Lead screw, Di, C2...
X-ray detector, Fl, F2...Base I31. Projection projecting from B2, Kl, 2... cam, Hl, H2, H
2'... Hit fixed to the EPMA body, pl, p2
... Swing axis fulcrum of base Bl, B2, CPU... control device. Agent Patent Attorney Kosuke Agata

Claims (1)

[Claims] An X-ray spectrometer for sample analysis whose viewpoint is located on the center line of the electron beam that irradiates the sample, and two X-ray spectrometers for sample position adjustment located on the center line of the electron beam with their viewpoints on either side of the above viewpoint. X-ray spectroscopy equipped with a control means that compares the outputs of the spectrometer and these two X-ray spectrometers for adjusting the sample position and drives the sample in the direction of the center line of the electron beam so that both outputs have a constant relationship Device.