JP3673825B2 - Oblique X-ray analysis method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention of this application relates to an oblique emission X-ray analysis method. More specifically, the invention of this application is a new oblique emission X-ray probe useful as an oblique emission electron probe micro X-ray analysis method for analyzing fine particles on a sample surface, minute inclusions observed on a sample polished surface, and the like. It relates to a line analysis method.
[0002]
[Prior art]
Conventionally, as a technique for analyzing a micro area of a sample, for example, as illustrated in FIG. 1A, a characteristic X-ray (1) irradiated with an electron beam (1) on a sample (3) and emitted from the irradiated micro area ( An electron beam probe micro X-ray analyzer (EPMA) that detects 2) with an X-ray detector (5) is known.
[0003]
However, in this conventional EPMA, for example, when a minute object (4) exists on the surface of the sample (3), characteristic X-rays (2 from both the inside of the sample (3) and the minute object (4) are obtained. (In FIG. 1, the generation area of the characteristic X-ray (2) from the inside of the sample (3) is shown in a pear shape), and it is difficult to analyze only the minute object (4). there were.
[0004]
In order to solve this problem, a new EPMA based on oblique emission X-ray measurement (hereinafter referred to as oblique emission EPMA) has already been proposed.
[0005]
This oblique emission EPMA utilizes the X-ray total reflection phenomenon. For example, as illustrated in FIG. 1B, the characteristic X-ray (2) of electron beam excitation is obtained by the X-ray detector (5). At the time of detection, the characteristic X-ray (2) from the inside of the sample (3) is set to the angle at which the characteristic X-ray (2) is taken below the angle at which it is not detected by the total reflection phenomenon. Only characteristic X-rays (2) from the minute object (4) can be detected.
[0006]
More specifically, for example, as illustrated in FIG. 2, the characteristic X-ray (2) generated from the minute object (4) is normally emitted in all directions in a vacuum. On the other hand, the characteristic X-ray (2) generated inside the sample (3) is obtained if the angle formed by the characteristic X-ray (2) with respect to the boundary surface between the surface of the sample (3) and the vacuum is greater than the critical angle. (3) It is emitted from the surface into a vacuum and is reflected at the boundary surface if it is less than the critical angle. This is the X-ray total reflection phenomenon. Focusing on this total reflection phenomenon, the criticality of the characteristic X-ray (2) generated inside the sample (3) is changed to the X-ray detector (5) in which the detection range of the characteristic X-ray (2) is limited by the slit (6). Only the characteristic X-ray (2) of the minute object (4) can be detected by adjusting to the angle or less. This makes it possible to realize excellent analysis of fine particles on the sample surface and minute inclusions observed on the sample polishing surface.
[0007]
[Problems to be solved by the invention]
However, even in the oblique emission EPMA having the excellent analysis capability as described above, problems to be further improved practically remain.
[0008]
This is because, in the oblique emission EPMA, for example, as illustrated in FIGS. 3A and 3B, the adjustment angle of the characteristic X-ray (2) (shown as the extraction angle θ with respect to the sample surface in FIG. 3) is adjusted. Furthermore, the inclination of the sample stage (7) is used (in FIG. 3, the sample (3) is installed on the sample stage (7) via the inclined sample stage (8) having an inclined surface), and therefore In addition, the mounting direction of the X-ray detector (5) and the tilt axis of the sample stage (7) must be orthogonal to each other. This is not applicable to a type of EPMA or scanning electron microscope in which the two are not orthogonal, such as a scanning electron microscope with an energy dispersive X-ray analyzer. Furthermore, there is also a concern that the observation field of view moves greatly when the sample stage (7) is tilted.
[0009]
The invention of this application has been made in view of the circumstances as described above, and has improved the prior art, regardless of the geometric positional relationship between the mounting direction of the X-ray detector and the tilt axis of the sample stage. It is an object of the present invention to provide a new oblique emission X-ray analysis method that enables adjustment of the characteristic X-ray extraction angle and suppresses fluctuations in the observation field during adjustment of the extraction angle.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention of this application is such that, when a characteristic X-ray from a minute object on the sample surface is detected by an X-ray detector, the characteristic X-ray from the inside of the sample is caused by the total reflection phenomenon. In the oblique emission X-ray analysis method in which the characteristic X-ray extraction angle is set below an undetected angle, a sample is placed on a sample stage having an inclined surface having an inclination axis different from the Z axis, and the sample is on the Z axis. By adjusting the position, the characteristic X-ray extraction angle is set to be equal to or smaller than the above angle, and the X-ray detector placed at a position other than the position where the tilt axis of the sample stage and the mounting direction of the X-ray detector are orthogonal to each other An oblique emission X-ray analysis method (claim 1) characterized by detecting characteristic X-rays from a minute object on a sample surface.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 4 is a diagram for explaining the oblique emission X-ray analysis method of the invention of this application. As shown in FIG. 4, in the invention of this application, when the characteristic X-ray (2) is detected by the X-ray detector (5), the position on the Z-axis of the sample (3) is adjusted. The extraction angle of the characteristic X-ray (2) is set to be equal to or less than an angle at which the characteristic X-ray (2) from the inside of the sample (3) is not detected due to the total reflection phenomenon.
[0012]
More specifically, in FIG. 4, the sample (3) is placed on the tilted sample stage (8) on the sample stage (7) as in FIG. In this case, when the position of the sample (3) on the Z-axis, that is, the position in the vertical direction is changed, the angle of the analysis point on the sample (3) with respect to the X-ray detector (5) changes, and the inclination The characteristic X-ray (2) is gradually taken out by the characteristic X-ray (2) being shielded by the inclined surface of the sample stage (8) and the slit (6) positioned in front of the X-ray detector (5). The range of will be limited. Therefore, by adjusting the position of the sample (3) on the Z-axis, the extraction angle of the characteristic X-ray (2) can be set to the above angle or less. The position adjustment can be performed with a Z-axis knob (also referred to as a Z movement knob) for adjusting the working distance of the sample stage (7).
[0013]
Thus, when the position adjustment on the Z-axis of the sample (3) is performed, the X-ray detector (5) is arranged differently from the conventional oblique emission EPMA described above. Specifically, as shown in FIG. 5, in the conventional oblique emission EPMA, the mounting direction of the X-ray detector (5) and the tilt axis of the sample stage (7) are orthogonal to each other in the positional relationship on the plane. In contrast to (A), in the case of carrying out the invention of this application, the X-ray detector (5) is placed at a position other than A, the secondary electron detector is at the position of A, and the sample stage (7) Becomes inclined with respect to the secondary electron detector.
[0014]
The characteristic X-ray (2) is excited not only by an electron beam but also by X-rays or charged particles. Therefore, in the oblique emission X-ray analysis method of the invention of this application, the detection target is not limited to the characteristic X-ray (2) of electron beam excitation, but characteristic X-rays (2) excited by other excitation sources. ). In any case, it goes without saying that the extraction angle of the characteristic X-ray (2) can be set by adjusting the position of the sample (3) on the Z-axis as described above.
[0015]
【Example】
FIG. 6 shows the detected intensities [cps] and Si of characteristic X-ray SiKα from Si and characteristic X-ray ZnLα from ZnO when zinc oxide (ZnO) particles on a silicon (Si) substrate are irradiated with an electron beam. It is the figure which illustrated the relationship with displacement amount (DELTA) Z [mm] of the Z direction of the sample stage which a board | substrate rides. However, it is assumed here that the working distance decreases as ΔZ increases.
[0016]
As is apparent from FIG. 6, the intensity of each characteristic X-ray also changes according to the displacement amount ΔZ, and it can be seen that only the characteristic X-ray ZnLα from the ZnO particles can be detected by appropriately setting ΔZ.
[0017]
FIG. 7A and FIG. 7B show the results of energy dispersive characteristic X-ray analysis when the displacement amounts ΔZ = 0 mm and 2.0 mm, respectively, for the sample.
[0018]
As shown in FIGS. 7 (a) and 7 (b), it can be understood that only the characteristic X-ray ZnLα from the ZnO particles can be detected strongly when the position of the sample is adjusted at a displacement ΔZ = 2.0 mm. . The peak intensities of SiKα and ZnLα in each case are as shown in the figure.
[0019]
FIG. 8 is a secondary electron image of ZnO particles on the Si substrate by a scanning electron microscope equipped with an energy dispersive characteristic X-ray analyzer.
[0020]
In the invention of this application, by setting the extraction angle by adjusting the position of the sample on the Z-axis, for example, as described above, only characteristic X-rays from ZnO particles on the Si substrate can be detected. It is not necessary to make the mounting direction of the line detector orthogonal to the tilt axis of the sample stage, and as is clear from FIG. 8, the ZnO particles can be accurately obtained even by a scanning electron microscope equipped with an energy dispersive characteristic X-ray analyzer. Can be captured. Further, even if the Z-axis height of the sample stage was changed, the visual field moved little, and observation within the same visual field was possible.
[0021]
Of course, the invention of this application is not limited to the above examples, and various modes are possible for details.
[0022]
【The invention's effect】
As described above in detail, the invention of this application makes it possible to adjust the characteristic X-ray extraction angle regardless of the geometric positional relationship between the X-ray detector mounting direction and the tilt axis of the sample stage, and Provided is a new oblique emission X-ray analysis method that suppresses fluctuations in the observation field during adjustment of the extraction angle. As a result, oblique emission EPMA can be promoted as a more versatile one that can be applied to scanning electron microscopes with all types of characteristic X-ray analyzers, and contribute greatly to the design and analysis of materials. Can do.
[Brief description of the drawings]
FIGS. 1A and 1B are diagrams illustrating a conventional EPMA and a conventional oblique emission EPMA, respectively.
FIG. 2 is a diagram for explaining detection of electron beam excitation characteristic X-rays in a conventional oblique emission EPMA.
FIGS. 3A and 3B are diagrams for explaining extraction angle setting in a conventional oblique emission EPMA. FIG.
FIG. 4 is a diagram illustrating an oblique emission X-ray analysis method according to the invention of this application.
FIG. 5 is a diagram for explaining the inclination direction of the sample stage and the arrangement of the X-ray detectors in the oblique emission X-ray analysis method of the invention of this application;
FIG. 6 is a diagram illustrating the relationship between the detected intensity of characteristic X-ray SiKα from Si and characteristic X-ray ZnLα from ZnO and the Z-direction displacement ΔZ when ZnO particles on a Si substrate are irradiated with an electron beam. It is.
7A and 7B are diagrams showing the results of energy dispersive characteristic X-ray analysis when the displacement amounts ΔZ = 0 mm and 2.0 mm, respectively.
FIG. 8 is a diagram showing a secondary electron image of ZnO particles on a Si substrate by a scanning electron microscope equipped with an energy dispersive characteristic X-ray analyzer.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electron beam 2 Characteristic X-ray 3 Sample 4 Minute object 5 X-ray detector 6 Slit 7 Sample stage 8 Inclined sample stand

Claims (1)

When detecting characteristic X-rays from a minute object on the sample surface with an X-ray detector, an oblique angle for setting the characteristic X-ray extraction angle to be equal to or less than an angle at which characteristic X-rays from the sample are not detected by the total reflection phenomenon In the outgoing X-ray analysis method,
A sample is placed on a sample stage having an inclined surface having an inclined axis different from the Z axis,
By adjusting the position of the sample on the Z-axis, the characteristic X-ray extraction angle is set to the angle or less,
Characteristic X-rays from minute objects on the sample surface are detected by an X-ray detector placed at a position other than a position where the tilt axis of the sample stage and the X-ray detector mounting direction are orthogonal to each other. Oblique emission X-ray analysis method.

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