JPH06267693A - X-ray irradiation device - Google Patents

Abstract

PURPOSE:To provide an X-ray irradiation device which can irradiate X-ray to simultaneously filfil indispensable diffraction conditions at the center section and the peripheral section of a specimen wide in area. CONSTITUTION:In the X-ray irradiation device irradiating X-ray onto a specimen 8, which is generated out of an X-ray tube 1 including inside for example, a thermal electron generating filament 2 wound in a spiral form, the X-ray tube 1 includes a plurality of filaments 2a, 2b, 2a,.... These filaments 2a, 2b, 2a,... are disposed in such a way that each axial core is formed roughly into a straight line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray irradiation device,
In particular, it relates to an X-ray irradiation device used for X-ray topography by X-ray diffraction.

[0002]

2. Description of the Related Art The Lang method and Berg-Barrett
An X-ray tube as shown in FIG. 4 was used for the X-ray irradiation device in the X-ray diffraction method such as the X-ray method. In FIG. 4, an X-ray tube 1 is provided with a hot cathode composed of a single spirally wound filament for thermoelectron generation 2 and a cylindrical rotating anticathode 3, and the filament 2 is a cylinder of the anticathode 3. It is located opposite to the side surface. The filament 2 and the anticathode 3 are in a vacuum tube (not shown). The length 1 of the filament 2 in the axial direction of the spiral shape is about 10 mm, and the width d of the spiral shape in the radial direction is about 1 mm. As the target 1, tungsten or the like is used for continuous X-rays, and iron, copper, or molybdenum is mainly used for characteristic X-rays.

The electron beam emitted from the filament 2 is converged by an electrode (not shown) and collides with the anode surface 4, and the anode surface 4
Then, the X-ray flux 5 is generated. The X-ray flux 5 is irradiated onto the sample through a slit or the like as necessary, and the X-ray diffracted from the sample is measured to obtain a screen such as an X-ray topograph.

[0004]

Problems to be Solved by the Invention Lang Method and Berg
When the Barrett method or the like is applied to a sample having a wide area, the X-ray tube 5 and the sample are separated from each other to increase the angular spread of the X-ray flux 5 to irradiate a wide area.

In the conventional X-ray irradiation apparatus, the X-ray tube is provided with only one filament 2. If the length 1 in the axial direction of one filament 2 is increased, the filament 2 is likely to be broken, and the length 1 in the axial direction of the spiral shape is limited, and the length 1 in the axial direction is It was about 10 mm at most.

For this reason, it was not possible to simultaneously satisfy the necessary diffraction conditions in the central portion and the peripheral portion of a large sample. At the same time, if the diffraction region that satisfies the diffraction condition is narrow, X
Scanning time is required because it is necessary to scan the flux. During this scanning time, there is a problem that the image quality of the X-ray topography is deteriorated due to changes in diffraction conditions and mechanical vibrations caused by temperature changes.

Further, in order to irradiate a sample having a large area with X-rays, the X-ray bundle 5 had to be irradiated with an angular spread, so that a non-parallel X-ray bundle was irradiated to the sample. However, there is a problem that the geometrical optical resolution is reduced due to the wide distribution of the incident angle and the diffraction angle.

Therefore, an object of the present invention is to eliminate the above-mentioned problems of the prior art, and to irradiate X-rays so that the necessary diffraction conditions are simultaneously satisfied in the central portion and the peripheral portion of a sample having a large area. It is to provide an X-ray irradiation device capable of performing the above.

[0009]

In order to achieve the above object, an X-ray irradiation apparatus according to the present invention is an X-ray that irradiates a sample with X-rays generated from an X-ray tube having a thermoelectron generating filament therein. In the irradiation apparatus, the X-ray tube has a plurality of the filaments, and the filaments are arranged so that their respective axial centers form a substantially straight line. The shape of the thermoelectron generating filament is, for example, a spiral shape. In addition, linear lanthanum hexaboride (LaB6) is used in place of the spiral filament, and the same arrangement is performed.

[0010]

The X-ray tube has a plurality of filaments, and these filaments are arranged so that the axes of the respective spirals or straight lines form a substantially straight line. It is possible to obtain an X-ray flux having a wide width for the beam component.

Further, since the width of the beam component of the beam component of the X-ray beam generated from the X-ray tube in the direction perpendicular to the axis of the filament is widened and the monochromator for collimating the beam component is provided. , It is possible to obtain a collimated X-ray flux having a wide width in the beam component in the direction perpendicular to the filament axis.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the X-ray irradiation apparatus according to the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of an X-ray tube 1 in the X-ray irradiation apparatus of this embodiment. The X-ray tube 1 includes a hot cathode composed of a filament 2 and a rotating anticathode 3 composed of a cylindrical Cu, and the filament 2 and the anticathode 3 are arranged in a vacuum tube (not shown).

The filament 2 comprises a plurality of thermoelectron generating filaments 2a, 2b, 2 each wound in a spiral shape.
It is composed of c ... Filaments 2a, 2b,
2c ... Each has a length in the axial direction of about 10 mm and a length of about 3
It has a radial width d of mm. In this embodiment, the number of filaments 2a, 2b, 2c, ... Is 13. These filaments 2a, 2b, 2c ...
Are arranged so that the axial direction of each spiral shape forms a substantially straight line at intervals. Therefore, the overall axial length l of the filament 2 is 140 mm. The width d in the radial direction is 3 mm or more, which is larger than the conventional value of 1 mm. The filament 2 is located so as to face the cylindrical side surface of the anticathode 3. The width of the side surface of the cylinder is about 140 mm. The material of the filament 2 is tungsten. The filament 2
As the material of the above, linear LaB6 or the like is also possible.

The electron beam emitted from the filament 2 is converged by an electrode (not shown) and collides with the anode surface 4, and the anode surface 4
Then, the X-ray flux 5 is generated. The anode surface 4 is a filament 2
Anode surfaces 4a, 4b, 4c corresponding to a, 2b, 2c ...
・ ・ It consists of. The length of the anode surface 4 in the longitudinal direction is the anode surface 4
It is an added value of the lengths in the longitudinal direction of a, 4b, 4c, ....

In the X-ray bundle 5, the filament 2 has an axial beam width (axial beam width) of about 130 mm, and the filament 2 has a beam width (radial beam width) of a direction perpendicular to the axial line of about 3 mm. .

FIG. 2 shows an X using the X-ray tube 1 shown in FIG.
The outline of a line irradiation device is shown. This X-ray irradiation device includes an X-ray tube 1, a monochromator 6, and a solar slit 7. As shown in FIG. 2A, the X-ray extraction angle of the X-ray tube 1 is about 6 degrees. The output intensity of the X-ray tube 1 is 6
It is 0 kV and 500 mA.

The monochromator 6 is made of single crystal Si (1,
It is formed by cutting out the (0, 0) plane. In the monochromator 6, the incident condition of the X-ray flux 5 emitted from the X-ray tube 1 is 422 asymmetrical reflection (Bragg angle = 44 degrees, incident angle = 8.8) in a plane parallel to the paper surface of FIG.
It is arranged so as to satisfy (degree).

The X-ray flux 5 incident on the monochromator 6 is diffracted into an X-ray flux 5a. The radial beam width of the X-ray flux 5a is the plane including the X-ray flux 5 and the X-ray width 5a, that is, FIG.
In the plane parallel to the paper surface of (a), it is about 7.1 times the radial beam width of the X-ray flux 5. The X-ray width 5a is
The beam divergence angle in the radial direction of the filament 2, that is, in the plane parallel to the paper surface of FIG. In addition,
The axial beam width of the X-ray flux 5a is approximately equal to the axial beam width of the X-ray flux 5 and is about 130 mm.

The solar slits 7 are parallel to each other and are about 0.
Many planar partition walls 7a, 7 arranged at intervals of 2 mm
b, 7c ... As shown in FIG. 2 (b), the solar slit 7 includes the partition walls 7 a, 7 b, 7
.. are arranged so as to be erected parallel to the direction perpendicular to the axis of the filament 2, that is, so as to be erected in the direction perpendicular to the paper surface of FIG. In addition to the solar slits 7, slits may be arranged parallel to the direction perpendicular to the axis of the filament 2.

X-ray flux 5a incident on the solar slit 7
Exits from the solar slit 7 and becomes an X-ray flux 5b.
The X-ray flux 5b is collimated by the solar slit 7 to reduce the beam divergence angle of the filament 2 in the axial direction. The resolution corresponding to the beam divergence angle of the filament 2 in the axial direction is (the size of the light source).
It is proportional to x (distance between sample and dry plate) / (passage path), but using the value used in the experiment described below, the resolution in this direction is 5 mm × 0.2 mm / 1 mm = 1 mμ, It can be seen that the X-ray irradiator has a very high resolution.

Since the X-ray flux 5b is collimated by the monochromator 6 before the solar slit 7, the beam divergence angle of the filament 2 in the radial direction is also small. That is, the X-ray flux 5b is an X-ray flux that is collimated so that the beam divergence angle becomes small in both the axial direction and the radial direction of the filament 2.

The beam width in the axial direction of the X-ray flux 5b is
It is approximately equal to the axial beam width of the X-ray flux 5a, that is, the axial beam width of the X-ray flux 5 and is about 130 mm. X
The radial beam width of the ray bundle 5b is substantially equal to the axial beam width of the X-ray bundle 5a, that is, 21 mm, which is approximately 7.1 times the radial beam width of the X-ray bundle 5.

Next, the result of irradiating the sample 8 with the X-ray flux 5b will be described. Sample 8 is a Si wafer having a diameter of 125 mm, and this Si wafer is obtained by cutting a (1, 0, 0) plane from single crystal Si. X-ray flux 5b
Is the X-ray flux 5b in a plane parallel to the paper surface of FIG.
Was irradiated so that the incident condition on the sample 8 satisfies 422 asymmetric reflection (Bragg angle = 44 °, incident angle = 8.8 °). The diffraction X-ray 5c diffracted from the sample 8 has a slit 9
After that, the nuclear dry plate 10 was exposed for about 15 minutes.

The X-ray flux 5 is transferred to the monochromator 6 at 42
2 is asymmetrically reflected, and further, the X-ray flux 5b is 422 asymmetrically reflected on the sample 8. Therefore, the radial beam width of the diffracted X-ray 5c is about 5 times the radial beam width of the X-ray flux 5.
It is 0 times 150 mm. The axial beam width of the diffracted X-ray 5c is 130 mm, which is substantially equal to the axial beam width of the X-ray flux 5b. That is, the diffracted X-ray 5c is diffracted from the entire surface of a Si wafer having a diameter of 125 mm.

The output from the nuclear plate 10 is the proportional counter 1
Counted by 1, an X-ray topograph as shown in FIG. 3 was obtained. In FIG. 3, symbol a and the like indicate crystal defects. The symbol b is due to the contour of the sample 8 and the symbol c is due to the surface strain of the sample 8. As can be seen from FIG. 3, the presence or absence of crystal defects on the entire surface of Sample 8 was obtained with clear contrast.

Incidentally, it was confirmed by the magnified observation of the image and the microscopic observation after the selective etching of the sample 8 that the X-ray topography thus obtained has a high resolution of about 1 mμ.

According to the configuration of this embodiment, the X-ray tube 1 has a plurality of filaments 2a, 2b, 2c ..., And the filaments 2a, 2b, 2c. Are formed so as to form an X-ray flux having a wide axial beam width of about 130 mm for the axial beam component of the filament.

Of the beam components of the X-ray generated from the X-ray tube 1, the beam width (radial beam width) of the beam component in the direction perpendicular to the axis of the filament is expanded and the beam component is parallelized. Since the monochromator 6 is provided, it is possible to obtain a collimated X-ray flux having a wide width of 21 mm, which is approximately 7.1 times the radial beam width of the X-ray flux 5 for the beam component in the direction perpendicular to the filament axis. You can

Since the width d of the filament 2 in the direction perpendicular to the axis is increased to about 3 mm as compared with the conventional width of about 1 mm, a large beam width can be obtained.

Since the solar slit 7 is provided, X
It is possible to efficiently collimate the beam component in the axial direction of the filament among the components of the X-ray beam generated from the ray tube 1.

The X-ray flux 5 is asymmetrically reflected by the monochromator 6 at 422, and the X-ray flux 5b is reflected by the sample 8.
At 422, asymmetric diffraction is performed, so that the diffraction X-ray 5
The beam width of c in the direction perpendicular to the filament axis is about 50 times as large as the beam width of the X-ray flux 5 in the direction perpendicular to the filament axis (approximately equal to the width d in the direction perpendicular to the axis of the filament 2). Can be wide.

Further, according to the structure of this embodiment, it is possible to obtain a collimated X-ray flux with a wide beam width, so that it is not necessary to scan the X-rays, and a high-contrast and high-resolution crystal defect image is obtained. Can be obtained in a short time. Utilizing this, the entire surface of the wafer can be evaluated non-destructively and in a short time with respect to dislocations, damages and the like induced when the VLSI is manufactured on the semiconductor surface. Further, since the distribution and position of defects in the device chip can be easily known, it is possible to easily identify at which stage of the manufacturing process the defect or the like occurred. As a result, the yield can be significantly improved on the manufacturing line.

[0033]

As described above, according to the present invention,
The X-ray tube has a plurality of filaments, and since these filaments are arranged so that their respective axes form a substantially straight line, an X-ray flux having a wide width with respect to the beam component in the axial direction of the filament is generated. Obtainable.

Further, since the width of the beam component of the beam component of the X-ray beam generated from the X-ray tube in the direction perpendicular to the axis of the filament is widened and the monochromator for collimating the beam component is provided. , It is possible to obtain a collimated X-ray flux having a wide width in the beam component in the direction perpendicular to the filament axis.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an X-ray tube in an X-ray irradiation apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view (a) showing a schematic configuration of FIG. 2 and a plan view (b) corresponding thereto.

FIG. 3 is a photograph of an X-ray topography showing crystal defects obtained by irradiating a Si wafer with an X-ray irradiator according to the present invention. a is a crystal defect, b is a wafer contour line, and c is a surface strain of the wafer.

FIG. 4 is a schematic configuration diagram showing an X-ray tube in a conventional X-ray irradiation device.

[Explanation of symbols]

 1 X-ray tube 2 filament 2a filament 2b filament 2c filament 3 rotating anticathode 4 anode surface 4a anode surface 4b anode surface 4c anode surface 5 X-ray flux 5a X-ray flux 5b X-ray flux 5c diffraction X-ray flux 6 monochromator 7 solar slit 7a partition wall 7b Partition 7c Partition 8 Sample (Si wafer) 9 Slit 10 Nuclear dry plate 11 Proportional counter

Claims (4)

[Claims] 1. An X-ray irradiator for irradiating a sample with X-rays generated from an X-ray tube having a thermoelectron generating filament therein, wherein the X-ray tube has a plurality of the filaments. Is an X-ray irradiator, wherein each axis is arranged so as to form a substantially straight line. 2. A monochromator for expanding the beam width and collimating the beam component of the beam component of the X-ray beam generated from the X-ray tube in a direction perpendicular to the axial direction of the filament. The X-ray irradiation apparatus according to claim 1, wherein 3. A plurality of slits for collimating the beam component in the axial direction of the filament among the beam components of the X-ray generated from the X-ray tube are provided, and the number of slits is small. The X-ray irradiation apparatus according to claim 1, wherein one is a solar slit. 4. A total of 10 of the plurality of filaments.
The X-ray irradiation apparatus according to claim 1, wherein the X-ray irradiation apparatus has a length in the axial direction of not less than mm and a width in the radial direction of not less than 3 mm.