JPH07280750A - Wavelength dispersion type x-ray spectroscope - Google Patents

Abstract

PURPOSE:To adjust the position of a specimen to a focusing point of an x-ray optical system with a relatively simple structure regarding a wavelength dispersion type x-ray spectroscope. CONSTITUTION:Laser light beams are so radiated from a first laser light source 2 and a second laser light source 4 as to make the light beam passage cross at the focusing point of an x-ray optical system. The position adjustment of a specimen 11 to the focusing point of the x-ray optical system is completed by moving the specimen 11 supported by a goniometer 14 to the point where the laser light beams cross mutually. After that, ion beam 1a is radiated from a radiation source 1 and spectroscopic analysis of the x-ray generated from the specimen 11 is carried out by a spectroscopic crystal 3 and the resulting spectral components are detected by a proportional counter 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength dispersion type X for irradiating a sample with radiation such as an X-ray or a charged particle beam and analyzing the bonding state of elements and atoms in the sample from the X-ray generated from the sample. The present invention relates to a line spectrometer.

[0002]

2. Description of the Related Art Generally, in a wavelength dispersive X-ray spectroscope, in order to disperse weak X-rays generated from a sample as efficiently as possible, for example, a curved dispersive crystal 51 (spectrometer) as shown in FIG. An X-ray optical system provided with is used (for example, Hiroyoshi Fukushima “Electron Beam Microanalysis” published by Nikkan Kogyo Shimbun P.63). The wavelength λ of the X-ray to be dispersed is given by 2d · sin θ = n · λ (1) when a crystal lattice is used as the spectroscope. Here, d is the crystal lattice spacing, and θ is the angle of incidence of X-rays from the sample 53 on the dispersive crystal 51. Although n is an integer (n = 1, 2, ...), it is often used when n = 1, which is the strongest intensity of the X-ray to be dispersed. The separated X-rays are reflected from the dispersive crystal 51 at an emission angle θ toward the X-ray detector 52. As shown in FIG. 3A, when the dispersive crystal 51, the X-ray emission point 53 _a on the sample 53 and the X-ray detector 52 are arranged on the same circumference, the X-ray generated from the sample 53 The light enters the crystal 51 at an equal angle to any place on the surface and is focused on the position of the X-ray detector 52 to maximize the efficiency and resolution of the device. This circumference is generally called the Roland circle.

By the way, when the position of the sample 53 is deviated from the circumference of the Rowland as shown in FIG. 2B, the X-rays generated from the sample 53 are incident at different angles depending on the location of the surface of the dispersive crystal 51. , Clearly different wavelengths are separated from the above formula (1). Therefore, the wavelength resolution is reduced. At the same time, the light collecting ability also decreases. This is the wavelength dispersion type X
This means that the X-ray optical system of the line spectroscope has a shallow depth of focus. This depth of focus is several tens of μ in the case of elemental analysis
m, several μm in the case of state analysis. So, conventionally,
For example, the above-mentioned “electron beam microanalysis” (P. 5)
As disclosed in 1) and Japanese Patent Publication No. 57-55184, there is proposed one in which an optical microscope is installed so that the focal point can be aligned by observing the sample surface. That is, as shown in FIG. 5, the focus position of the optical microscope and the focus position of the X-ray optical system are adjusted in advance. Therefore, while observing the sample surface with this optical microscope and adjusting the sample to move it to the focal position, the sample is set in the depth of focus region of the dispersive crystal (not shown), and Be analyzed. Although the above description has been made mainly for the case of the crystal X-ray spectroscope, it is also generally applicable to the diffraction type X-ray spectroscope such as the artificial multilayer film and the diffraction grating.

[0004]

However, in order to install such an optical microscope, it is necessary to secure a relatively large area (solid angle). Especially, in an ion beam excitation type X-ray spectrometer, In addition to the wavelength dispersive X-ray spectrometer, a recoil ion analyzer, secondary electron detector, energy dispersive X-ray detector, etc. must be installed in order to perform multifaceted analysis of the sample. At present, there is no room to install such an optical microscope. Therefore, the present invention was devised in view of the above circumstances, and made it possible to adjust the position of the sample to the focal position of the X-ray optical system with a relatively simple structure, thereby making it compact or It is an object of the present invention to provide a wavelength dispersive X-ray spectroscopic device that enables installation of other detection equipment and the like due to space saving.

[0005]

In order to achieve the above-mentioned object, the main means adopted by the present invention is to provide a sample whose position is adjusted by a position adjusting mechanism at the focal position of the X-ray optical system. In the wavelength-dispersive X-ray spectroscope that irradiates radiation from a radiation source toward the X-ray detector, disperses the X-rays from the sample with a diffraction type spectroscope, and then detects them with an X-ray detector. And a second light beam irradiating means for irradiating light beams from different directions so that the sample is located at a position where the optical path intersects by driving the position adjusting mechanism. Distributed X
It is a line spectrometer. The light rays in the above-described configuration are a concept including visible light such as laser light, near-ultraviolet rays, near-infrared rays, and also radiation such as ion beams and X-rays.

[0006]

In the X-ray spectroscope according to the present invention, since the optical paths of the light rays emitted from the first and second light ray irradiation means are set in advance so that they intersect at the focal position of the X-ray optical system, By operating the position adjusting mechanism so that the sample is located at the position where the optical paths intersect, the sample can be easily positioned with respect to the focal position of the X-ray optical system.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the accompanying drawings for the understanding of the present invention. The following embodiments are examples of embodying the present invention and are not intended to limit the technical scope of the present invention. Here, FIG. 1 is a schematic configuration diagram of an X-ray spectroscope according to an embodiment of the present invention, FIG. 2 is a graph showing a result of analyzing zinc silicate by the X-ray spectroscope, and FIG. FIG. 3 is a schematic configuration diagram of an X-ray spectroscopic device according to the example of FIG. First, an example in which the present invention is applied to an ion beam excitation type X-ray spectrometer is shown in FIG.
Shown in. That is, the X-ray spectroscopic apparatus A according to the present embodiment irradiates the ion beam 1 _a from the radiation source 1 toward the sample 11 which is pre-positioned at the focal position of the X-ray optical system as described later, and the sample 11 The X-ray generated from the X-ray is dispersed by the dispersive crystal 3, and only the X-ray of the target wavelength is proportional to the proportional counter 6
(X-ray detector) is configured to guide and detect. Since the ion beam 1 _a does not pass through the atmosphere, the sample 11 is placed in a vacuum, and a load lock mechanism 12 is provided for attaching and detaching the sample 11.
Then, through the load lock mechanism 12, the sample 1
1 is placed on the goniometer head 13 in vacuum.
The position of the sample 11 supported by the goniometer head 13 is adjusted by a goniometer 14 (position adjusting mechanism), and the sample 11 is positioned at the focus position.

In this case, in the apparatus of this embodiment, the first laser light source 2 (first light beam irradiating means) and the second laser light source 2 for irradiating, for example, laser light from different directions are arranged so that the optical paths intersect at the focal position. The laser light source 4 (second light beam irradiating means) is provided. Therefore, the sample 11 is simply adjusted by driving the goniometer 14 at a position where the light beams intersect to adjust the position of the sample 11. It can be easily positioned at the focal position of the X-ray optical system. As described above, the observation of whether or not the sample 11 is located at the position where the light beams intersect is performed by, for example, C placed in the space of the device.
It is performed through the image from the CD camera 5. In the following, the above-mentioned configuration will be described in detail, and the position adjustment procedure of the first and second laser light sources 2 and 4 to be performed at the time of assembling or maintenance of the device will also be described. The proportional counter 6 is filled with argon gas inside, and the X-ray entrance window 8 for entering X-rays is made of a polymer film with a thickness of 1 μm supported by an optically transparent stainless mesh. Has been done. An optical window 7 is disposed at a position facing the X-ray incident window 8 so that the laser light from the first laser light source 2 passes through the optical window 7 and the X-ray incident window 8 and the proportional counting is performed. The light is emitted toward the dispersive crystal 3 coaxially with the optical axis of the X-ray with respect to the tube 6. In this case, the first laser light source 2 corresponds to the first visible light source.

On the other hand, the second laser light source 4 is arranged at a position where the laser light from the first laser light source 2 can be irradiated from a different direction. Continuing,
The procedure for adjusting the second laser light sources 2 and 4 and the dispersive crystal 3 will be described. First, for initial adjustment, a phosphor that emits visible light by irradiating the ion beam 1 _a is prepared as a sample. In this case, the surface of the sample 11 may be coated with a phosphor for use. When the ion beam 1 _a is irradiated, only the irradiated position on the sample surface emits light. Therefore, the light emission point and the light emission on the sample due to the laser light irradiation from the first laser light source 2 are emitted. The proportional counter 6 is moved together with the laser light source 2 of the table 1 in the direction of arrow 10 so that the points coincide with each other, and the position is adjusted. That is, the laser light emitted from the first laser light source 2 is reflected by the surface of the dispersive crystal 3 and illuminates the sample surface. Here, the surface of the dispersive crystal 3 is mirror-finished in advance in order to prevent parasitic scattering of X-rays. Similarly, the laser light from the second laser light source 4 is irradiated,
The position of the second laser light source 4 is adjusted so that the second laser light source 4 is positioned at the light emitting point on the surface of the sample. It should be noted that the confirmation as to whether or not the light emitting points coincide with each other as described above is performed through the image from the CCD camera 5.

The positioning of the first and second laser light sources 2 and 4 with respect to the focal position of the X-ray optical system is performed as described above. Further, in order to optimize the wavelength resolution in the intended X-ray spectroscopy, the dispersive crystal 3 is rotationally adjusted in the direction of the arrow 9, and the first laser light source 2 and the first laser light source 2 on the arm 18 interlocked therewith are adjusted. The proportional counter 6 is moved.
As _{a result} , the distance from the irradiation point of the ion beam 1 _a to the dispersive crystal 3 is adjusted. Here, the dispersive crystal 3
The incident angle of X-rays on the X-ray may be adjusted so as to operate within a range of ± 1 to 2 degrees centered on the angle given by the equation (1). Thus, during X-ray spectroscopy, the proportional counter 6 is moved with respect to the dispersive crystal 3 so that the position where the first laser light source 2 irradiates the sample 11 always coincides with the irradiation point of the ion beam 1 _a . Therefore, it is possible to adjust extremely easily while maintaining the accuracy of the optical axis and the focus position in the X-ray optical system. When a sample is analyzed by the apparatus adjusted as described above, first, the sample 11 is placed on the goniometer head 13 in vacuum through the load lock mechanism 12. Subsequently, the sample 11 is irradiated with laser light from the first and second laser light sources 2 and 4 so that the two emission points on the sample 11 coincide with each other.
4 is operated in the Z-axis direction (the irradiation direction of the ion beam 1 _a ). As described above, the position of the sample 11 can be adjusted to the focal position of the X-ray optical system.

When the position adjustment of the sample 11 is completed as described above, the irradiation of the first and second laser light sources 2 and 4 is stopped and the irradiation of the ion beam 1 _a from the radiation source 1 is started. . Then, as in the case of the above-described initial adjustment, the dispersive crystal 3 is rotated in the direction of the arrow 9, and the proportional counter 6 and the first laser beam 2 are moved in accordance with this operation. Here, when the ion beam 1 _a is irradiated, X-rays having different wavelengths are generated for each element. Therefore, the angle corresponding to the wavelength of the X-rays of the element to be analyzed is obtained according to the above equation (1), and this angle The dispersive crystal 3 is rotated so that the incident angle and the reflected angle of the X-rays with respect to the dispersive crystal 3 coincide with each other within a range of 1 to 2 degrees around the The laser light source 2 is moved.
For example, when performing a qualitative analysis of oxygen (presence or absence of oxygen), the X-ray wavelength peculiar to oxygen is 23.62Å, and if an artificial multilayer film having a lattice spacing of 40Å is used as the dispersive crystal 3, X From the equation (1), the incident angle of the line is n
A value of 17.2 degrees is obtained when = 1. Therefore, the dispersive crystal 3 may be rotated so that the value of the incident angle is within the range of 16.2 to 18.2 degrees. Fig. 2 shows the results of analyzing oxygen in zinc silicate by the device. In this case, in addition to oxygen X-rays (OKα) as analysis targets, X-rays (ZnLα) generated by zinc are observed as interfering X-rays (this X-ray is in the case of n = 2 in equation (1)). However, in this apparatus, the focus position adjustment in the X-ray optical system is performed with sufficient accuracy.

Incidentally, the X-ray spectroscopy according to this embodiment shown in FIG.
In the device A, in addition to the analyzing crystal 3 described above, recoil ions
Analyzer 15, energy dispersive X-ray spectrometer 16, secondary
Equipped with an electronic detector 17, etc., to analyze samples in multiple directions
can do. Further, the X-ray spectroscopic apparatus according to the above embodiment
In this case, the radiation source 1 is used as the second light beam irradiation means.
The second laser light source 4 is omitted, and
It is also possible to achieve simplification. In this case, dummy beforehand
Ion beam 1 by coating the surface of the material as a phosphor
_aAnd the laser from the first laser light source 2
Goniometer 14 so that the emission point by the light matches
Position. Then, the position is adjusted to the adjusted position.
Replace the sample to be analyzed with the dummy above and
The position of the radiation source 1 is adjusted again by the data source 14.
Beam 1_aBy irradiating
It is possible. FIG. 3 shows another embodiment of the present invention.
The related X-ray spectroscopic apparatus B is shown. X-ray spectroscopy according to this example
The device B applies the radiation 27 from the radiation source 20 to the sample 11.
Irradiate and analyze the X-ray generated from this sample 11.
It is the one. That is, in the X-ray spectrometer B, the radiation
The radiation 27 generated from the radiation source 20 is reflected by the collimator 21.
The sample 11 is irradiated with a narrow beam. Release
X-rays 28 generated from the sample 11 irradiated with the rays 27
The semiconductor crystal 29 (X-ray detection)
Guide). As the dispersive crystal 31, for example, silicon
Single crystals of germanium and germanium are used.

Between the radiation source 20 and the collimator 21, and between the dispersive crystal 31 and the semiconductor detector 29, there are disposed polymer thin films 24 and 25, which are examples of light metal element thin films, on which aluminum is deposited. ing. The laser light source 22 (second light beam irradiation means, second visible light source) and the laser light source 23 are provided corresponding to the polymer thin films 24 and 25.
(First light irradiating means, first visible light source) are respectively provided, and laser light 2 from the laser light sources 22 and 23 is provided.
6, 35 are configured to be guided to the optical axis of the X-ray optical system. Here, also in the X-ray spectroscope B, the laser light sources 22, 2 are processed in the same procedure as in the case of the X-ray spectroscope A.
3, the position adjustment of the dispersive crystal 31 and the semiconductor detector 29 is performed, and the laser light source 23 and the semiconductor detector 29 swing together with the polymer thin film 25 to swing together with the swing operation of the dispersive crystal 31. 19 supported. Also in this device, a CCD for observing the sample surface
In order to prevent unnecessary irradiation of the camera 33 and radiation,
A shutter 34 is provided on the front surface of the radiation source 20.

In order to prevent exposure to radiation, the entire device is housed in a shielding box 30 to enable measurement in the atmosphere. Here, thin aluminum sufficiently transmits X-rays generated by elements heavier than phosphorus. For example, 0.4 μm thick aluminum has 16% X-rays generated by phosphorus and 40% X-rays generated by argon.
To Penetrate. For elements heavier than this, the transmittance increases further, indicating that there is sufficient transmittance for analysis. Further, the polymer film absorbs less X-rays than aluminum and has no influence on the analysis. Therefore, when the laser light 26, 35 is emitted from the laser light sources 22, 23, the laser light is reflected by the polymer thin films 24, 25 on which aluminum is vapor-deposited and introduced along the optical axis of the X-ray optical system. Further, the one laser beam 26 is emitted from the collimator 21.
The sample 11 is irradiated with the light through the slit. The other laser beam 35 is reflected on the surface of the spectroscopic crystal 31 that has been mirror-polished, and irradiates the sample 11. Both laser light 2
Since the reference numerals 6 and 35 are adjusted in advance so as to intersect at the focal position of the X-ray optical system, the CCD camera 33
While observing the sample surface, the position of the sample 11 is adjusted so that the positions where the two laser beams 26 and 35 irradiate the sample surface coincide with each other, and the focus position adjustment of the sample 11 by the X-ray optical system is completed. Then, prior to the measurement, the rotary stage 3
2 is rotated to align the direction of the dispersive crystal 31 with an angle corresponding to the wavelength of the X-ray to be dispersed according to the above formula (1), and is supported by the arm 19 at a corresponding position in conjunction with this. The semiconductor detector 29 is moved. This arm 1
Reference numeral 9 indicates a laser light source 2 together with the semiconductor detector 29.
3, the polymer thin film 25 is also supported.

When the incident angle of X-rays on the dispersive crystal 31 is changed in this manner, the focal length of the X-ray optical system also changes, so that the distance between the dispersive crystal 31 and the sample 11 can be adjusted. . At this time, the laser light sources 22 and 23 are operated again to confirm the focus position. With the above, the adjustment in the X-ray optical system is completed, the shutter 34 is opened, and the radiation 27
And the amount of X-rays dispersed by the dispersive crystal 31 is measured by the semiconductor detector 29. As described above, also in the X-ray spectroscopic apparatus B of the present embodiment, the focus position adjustment in the X-ray optical system can be performed very simply as in the case of the X-ray spectroscopic apparatus A described above. Further, the position of the semiconductor detector 29 with respect to the sample 11 can be easily adjusted.

[0016]

As described above, the present invention irradiates the sample whose position is adjusted by the position adjusting mechanism at the focal position of the X-ray optical system with the radiation from the radiation source to emit X-rays from the sample.
In a wavelength dispersive X-ray spectroscopic device in which rays are separated by a diffractive spectroscope and then detected by an X-ray detector, first and second light rays are emitted from different directions so that the optical paths intersect at the focal position. The X-ray optics is a wavelength dispersive X-ray spectroscope characterized in that the sample is positioned at a position where the optical paths intersect by driving the position adjusting mechanism by means of two light irradiating means. It is possible to adjust the position of the sample to the focal position of the system with a relatively simple structure. Further, with the above configuration, it is possible to install other detectors or the like by making the entire apparatus compact or saving space.

[Brief description of drawings]

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

FIG. 2 is a graph showing the results of analyzing zinc silicate by the above X-ray spectroscope.

FIG. 3 is a schematic configuration diagram of an X-ray spectroscopic device according to another embodiment of the present invention.

FIG. 4 is an explanatory view of the principle of a wavelength dispersion type X-ray spectrometer.

FIG. 5 is a diagram for explaining a sample position adjusting mechanism in a conventional wavelength dispersive X-ray spectroscope.

[Explanation of symbols]

1, 20 ... Radiation source 1 _a ... Ion beam 2 ... First laser light source (first light beam irradiation means) 3, 31 ... Spectroscopic crystal (spectrometer) 4 ... Second laser light source (second light beam irradiation means) ) 6 ... Proportional counter (X-ray detector) 11 ... Sample 14 ... Goniometer (position adjustment mechanism) 22 ... Laser light source (second light beam irradiation means, second visible light source) 23 ... Laser light source (first light beam) Irradiation means, first visible light source) 24, 25 ... Polymer thin film 26, 35 ... Laser light 27 ... Radiation 28 ... X-ray 29 ... Semiconductor detector (X-ray detector) A, B ... X-ray spectroscopic device

Claims (5)

[Claims] 1. A radiation source irradiates a sample whose position is adjusted by a position adjusting mechanism at a focal position of an X-ray optical system, and X-rays from the sample are dispersed by a diffraction type spectroscope. , A wavelength dispersive X-ray spectroscopic device for detecting with an X-ray detector is provided with first and second light beam irradiation means for irradiating light beams from different directions so that the optical paths intersect at the focal position, and the position adjustment is performed. A wavelength dispersive X-ray spectroscopic device characterized in that the sample is located at a position where the optical paths intersect by driving a mechanism. 2. A first visible light source, wherein the first light beam irradiation means makes visible light incident from the X-ray detector side toward the spectroscope coaxially with the optical axis of X-rays to the X-ray detector. The wavelength dispersive X-ray spectrometer according to claim 1. 3. The wavelength dispersive X-ray spectroscope according to claim 1, wherein the radiation source is used as the second light beam irradiation means. 4. The wavelength dispersive X-ray spectroscope according to claim 1, wherein the second light beam irradiation means is a second visible light source that makes visible light incident coaxially with the optical axis of the radiation from the radiation source. apparatus. 5. The wavelength dispersive X-ray spectroscopic apparatus according to claim 2, wherein the first and / or second visible light source is a laser light source.