JP2584865B2 - Semiconductor X-ray detector for analytical electron microscope - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analytical electron microscope capable of simultaneously observing an electron microscope image and X-ray analysis, and more particularly to a semiconductor X-ray detector for detecting X-rays. It is about structure.

2. Description of the Related Art Conventionally, an analytical electron microscope has been known as one that simultaneously performs observation of an electron microscope image of a sample and X-ray analysis for elemental analysis of the sample. FIG. 5 shows an outline of the configuration.

In FIG. 5, an electron beam emitted from an electron gun 1 is converged and / or deflected by an electron lens group 3 and irradiated on a sample 4. The electron beam transmitted through the sample 4 is enlarged and projected by the electron lens group 5 on the fluorescent screen 6 arranged in the observation room 7. Further, the characteristic X-ray is generated from the sample 4 by the irradiation of the electron beam 2.
The X-rays are usually detected by an X-ray detector 8 composed of a semiconductor detector in which lithium is diffused in silicon, and a desired analysis is performed in an X-ray analyzer 9.

With the above configuration, it is possible to simultaneously perform an electronic analysis of the sample while observing an electron microscope image.

[Problems to be Solved by the Invention] In a transmission electron microscope type analytical electron microscope as shown in FIG. 5, the sample 4 has an objective lens, as shown in FIG. An X-ray detector 8 is arranged between a pole piece lower pole 11 and a pole piece lower pole 11 having a substantially trapezoidal shape. The sensitive area surface of the conventional X-ray detector 8 is circular. Considering the most desirable position of the X-ray detector 8 in such a configuration is as follows.

First, in order to detect X-rays with high sensitivity, an X-ray detector 8 is required.
Needs to be as close to the sample 4 as possible. That is, the sixth
In the figure, the sensitivity can be improved by shortening the distance between the measurement point P of the sample 4 and the center point Q of the sensitive area surface 13 of the X-ray detector 8. The angle θ ₀ between the surface of the sample 4 and the line segment PQ is called an extraction angle, and it is generally considered that the larger the extraction angle is, the more desirable it is. The reason for this is that as the take-out angle is larger, the unevenness of the sample is not affected, and the influence of X-ray absorption by the sample is smaller.

Further, in FIG. 6, the X-ray generated from the measurement point P is
Angle at which the sensitive area surface 13 is viewed from the measurement point P, that is, θ _{1 to} θ
Although will be detected by the _two range and the angular range is large, the X-ray absorption at the measurement point P is different, it means that the fall quantitative accuracy, the sensible region surface 13 from the measurement point P It is desirable that the viewing angle is small.

However, according to the conventional configuration, since the cross-sectional shape of the pole piece upper pole 10 is substantially trapezoidal, the arrangement of the X-ray detector 8 is spatially limited, and both the sensitivity and the extraction angle can be satisfied. It could not be placed in a position.
That is, in FIG. 6, when the X-ray detector 8 is arranged near the sample 4 in order to improve the detection sensitivity, not only the extraction angle becomes small and the accuracy of the extraction angle is reduced, but also the measurement point P Since the angle of view of the sensitive area 13 is widened, the quantitative accuracy is deteriorated, and if the extraction angle is increased, the distance between the measurement point P and the X-ray detector 8 is increased, so that the detection sensitivity is deteriorated.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a semiconductor X-ray detector for an analytical electron microscope capable of improving the accuracy of an X-ray extraction angle and the X-ray detection sensitivity. .

Means for Solving the Problems In order to achieve the above object, a semiconductor X-ray detector for an analytical electron microscope according to the present invention has a sensitive area surface having an elliptical shape,
It has a major axis and a minor axis, such as an ellipse, a chamfered rhombus, or a chamfered rectangle, and has a chamfered shape.

[Functions and Effects of the Invention] The present invention has a shape of the sensitive area surface of the X-ray detector having a major axis and a minor axis such as an ellipse, an ellipse, a chamfered rhombus or a chamfered rectangle. In addition, since the shape is chamfered, the accuracy of the X-ray extraction angle can be improved, and the distance between the sample and the X-ray detector can be shortened, so that the X-ray detection sensitivity can be improved.

Further, even when the distance between the upper pole and the lower pole of the pole piece of the objective lens is small, the take-out angle can be increased, so that the space of the objective lens can be effectively used.

[Example] Hereinafter, an example will be described with reference to the drawings.

In the present invention, the shape of the sensitive area surface of the X-ray detector has a major axis and a minor axis, such as an ellipse, an ellipse, a chamfered rhombus or a chamfered rectangle, and is chamfered. Shape. FIGS. 1 (a) and 1 (b) show an embodiment of the present invention. In FIG. 1 (a), the sensitive area surface is an ellipse, and in FIG. 1 (b), it is an ellipse. In addition, it is also effective to use a rhombus or a rectangle, but it is necessary to chamfer corners so that the electric field is not concentrated and the resolution is not reduced as a result.

The effect of making the shape of the sensitive area surface have a major axis and a minor axis, such as an ellipse, an ellipse, a chamfered rhombus or a chamfered rectangle, and a chamfered shape is as follows. It is.

Now, the area of the sensitive area surface is assumed to be 30 mm ² required, if the sensitive area surface is circular, its diameter of about 6.
In the case of an ellipse as shown in FIG. 1 (a), the short axis d ₁ is about 4.4 mm and the long axis d ₂ is about 8.4 mm. can do. Fig. 1 (b)
The same applies to the case shown in FIG. And in transmission electron microscopes, etc., in order to improve the performance of the objective lens,
The interval between the upper pole and the lower pole of the pole piece may be reduced, in which case the spatial restriction of arranging the X-ray detector becomes severe, but in the present invention, the shape of the sensitive area surface is:
It has a long axis and a short axis, such as an ellipse, an ellipse, a chamfered rhombus or a chamfered rectangle, and has a chamfered shape, and the short axis is shorter than that of the conventional one. So, by aligning the short axis with the pole piece upper pole,
Even when the distance between the upper and lower poles of the pole piece is small, X
The line detector can be arranged close to the sample.
This will be described later.

FIG. 2 is a diagram showing the difference in quantitative sensitivity between the conventional X-ray detector 20 having a circular sensitive area surface and the X-ray detector 21 according to the present invention. Even if the area of the sensitive area surface and the extraction angle are the same, the angle at which the X-ray detector 20 is viewed from the measurement point P is ΔQ ₁ PQ ₄ , whereas the X-ray detector 21 is The expected angle is ΔQ ₂ PQ ₃ , which is smaller than the conventional one. Therefore, the X-ray detector 21 according to the present invention can improve the quantitative sensitivity as compared with the conventional X-ray detector 20.

Further, the X-ray detector according to the present invention can increase the extraction angle as compared with the conventional X-ray detector. That is,
As shown in FIG. 3, if the X-ray detector is arranged along the extraction angle, the shape of the sensitive area surface according to the present invention is as follows.
The X-ray detector 26 having a long axis and a short axis such as an ellipse, an ellipse, a chamfered rhombus or a chamfered rectangle, and a chamfered shape has a short-axis side of a pole piece. By setting the extraction angle φ ₁ along the upper pole 10, the extraction angle φ of the conventional X-ray detector 25 in which the shape of the sensitive area surface is circular is set.
It can be larger than ₂ . Further, the position of the conventional X-ray detector 25 is changed to the position indicated by 25 'in FIG.
And the distance between the center of the sensitive area surface of the X-ray detector 25 'and the sample 4
When the X-ray detector 26 is moved to a position equal to the distance of the center of the sensitive area surface to make the X-ray detection sensitivity equal,
Take-out angle φ ₃ becomes smaller. As described above, the X-ray detector of the present invention can approach a sample with a large extraction angle.

The X-ray detector is the same when inserted in a direction perpendicular to the optical axis as shown in FIG. 4, take-out angle alpha ₂ of the X-ray detector 28 according to the present invention, conventional X-ray detector 27 Extraction angle α
It can be seen that it can be greater than _one .

In the above description, the cross-sectional shape of the pole piece upper pole is substantially trapezoidal, but it is apparent that other shapes may be used.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of a semiconductor X-ray detector for an analytical electron microscope according to the present invention, and FIGS. 2, 3, and 4 are conventional X-ray detectors and an X-ray detector according to the present invention. FIG. 5 is a diagram for explaining a comparison with an analyzer, FIG. 5 is a diagram showing a configuration example of an analytical electron microscope,
FIG. 6 is a view for explaining the shape and arrangement of a conventional X-ray detector. 1 ... electron gun, 2 is electron beam, 3 ... electron lens group,
4 sample, 5 electron lens group, 6 fluorescent screen, 7
... Observation room, 8 ... X-ray detector, 9 ... X-ray analyzer, 10
…… pole piece upper pole, 11 …… pole piece lower pole, 12…
…optical axis.

Claims (1)

(57) [Claims] 1. A sensitive area surface has a major axis and a minor axis, such as an ellipse, an ellipse, a chamfered rhombus or a chamfered rectangle, and is chamfered. A semiconductor X-ray detector for an analytical electron microscope.