JP2001289803A - X-ray fluorescence analyzer, X-ray detector used therefor, and method for manufacturing X-ray entrance window of such detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the performance of a fluorescent X-ray analyzer and an X-ray detector by proposing a novel window member capable of detecting fluorescent X-rays in a wide range of a hard X-ray region and a soft X-ray region. Plan. SOLUTION: A sample S placed in a vacuum sample chamber 100 is irradiated with X-rays from an X-ray tube 200, and fluorescent X-rays KX generated from the sample are separated by a spectroscopic element 350. In the X-ray fluorescence analyzer for measuring and analyzing the intensity of the X-ray detector 400, the window member of the entrance window 420 of the X-ray detector 400 for measuring the intensity of the fluorescent X-ray is
On the support member 431 provided with the mesh opening 433,
For example, the thin film layer 432 is formed by sputtering and depositing a substance having an absorption edge near the short wavelength side of fluorescent X-rays, such as boron, carbon, boron carbide, boron nitride, boron oxide, or carbon nitride.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray fluorescence analyzer for analyzing a sample by measuring X-ray fluorescence, and an X-ray analyzer therefor.
X-ray detectors, especially X-ray detectors in such devices and detectors
The present invention relates to the structure of the X-ray entrance window, and further relates to a method of manufacturing such an X-ray entrance window.

[0002]

2. Description of the Related Art Conventionally, for example, a fluorescent X-ray analyzer for analyzing a sample by irradiating the sample placed in a vacuum analysis chamber with X-rays to measure the fluorescent X-ray generated from the sample has been known in various fields. Are already widely used for the analysis of various substances. Further, in such a fluorescent X-ray analyzer, a proportional counter is generally used as an X-ray detector for measuring fluorescent X-rays generated from a sample. , Two types, a sealed type and a gas flow type, are used.

A sealed X-ray detector (proportional counter)
Is a container in which a detection gas such as Ar or Ne is sealed in a highly airtight container, and is currently mainly used because of its easy handling. The window material of such an enclosed X-ray detector has a thickness of about 12 μm (1 μm) in order to satisfy both requirements of high airtightness and good X-ray transmittance.
A beryllium thin plate of 2 μm ± 2 μm) is mainly used, and such a beryllium thin plate is used as its window material.
The line detector has high detection efficiency mainly in a so-called hard X-ray region whose wavelength is 1 nm or less.

On the other hand, in a so-called soft X-ray region within a wavelength range of about 1 nm to 10 nm, a gas flow type X-ray detector (proportional counter) having relatively high detection efficiency even for soft X-rays is used. Are mainly used. This is because, for a beryllium thin plate having a thickness of about 12 μm,
This is because the X-ray transmittance in the so-called soft X-ray region having a wavelength of 1 nm or more is sharply reduced. A polymer film (for example, a polyimide film) having a high line transmittance and a thickness of about 1 μm is used. In the case of an X-ray detector using this polymer film as a window material, it is necessary to keep a fresh detection gas constantly flowing into the detector during its operation in consideration of its airtightness. Therefore, it is necessary to stabilize the detection efficiency (stabilize the gas concentration in the detector).

[0005]

That is, in the above-mentioned prior art, in particular, in a fluorescent X-ray analyzer employing an enclosed X-ray detector, the inherent characteristics of the enclosed X-ray detector (that is, the detector The supply of the detection gas into the inside becomes unnecessary, but the handling is relatively easy. However, in the soft X-ray region having a wavelength of about 1 nm to 10 nm, the light is transmitted due to the properties of the window material (beryllium thin plate). This has the disadvantage that the efficiency drops sharply and the detection efficiency for soft X-rays of long wavelengths is extremely deteriorated.

On the other hand, in a fluorescent X-ray analyzer using a gas flow type X-ray detector using a polymer film having a thickness of about 1 μm as a window material, X-rays (soft X-rays) in a long wavelength region are also used. Although it is possible to obtain relatively high detection efficiency,
However, since it is necessary to always supply fresh detection gas during the operation, the structure becomes complicated, and there is a disadvantage that the device itself becomes very difficult to handle.

In view of the above-mentioned problems in the prior art, the present invention employs a novel window member to provide a hard X
Not only for the line region, but also for soft X-rays in the long wavelength region
Fluorescent X that can exhibit sufficient detection efficiency over a wide range and has a simple structure and easy handling
It is an object of the present invention to provide an X-ray analyzer and an X-ray detector therefor, and also to provide a method for manufacturing such an X-ray incident window.

[0008]

In order to achieve the above object, the present invention provides an X-ray wavelength having a large absorption as compared with a hard X-ray region having a relatively small absorption in a substance (wavelength of about 1 nm or less). This is done by paying attention to the X-ray absorption (transmittance) characteristics in a region, that is, a soft X-ray region (wavelength of about 1 to 10 nm) in which the transmittance is easily reduced.

More specifically, the fluorescent X-rays (wavelength to be detected) detected in the soft X-ray region and the window member forming the incident window of the X-ray detector are connected, particularly in the soft X-ray region. As such, the absorption edge showing the maximum value of the transmittance characteristic of the substance forming the window member is located near the short wavelength side of the detected wavelength,
In other words, the detected wavelength is selected as a window member by selecting a substance located in the vicinity of the long wavelength side of the absorption edge, so that the X-ray wavelength in the soft X-ray region necessary for X-ray fluorescence analysis is reduced. It is based on the knowledge of the present inventors that it is possible to obtain sufficient transmittance even if the fluorescent X-rays are detected not only in the hard X-ray region but also in the soft X-ray region. It is intended to realize a simple X-ray detector and improve the performance of the fluorescent X-ray analyzer.

That is, according to the present invention, in order to achieve the above object, first, a sample placed in a sample chamber is irradiated with X-rays from an X-ray tube, and fluorescent X-rays generated from the sample are spectrally separated. Means, and the intensity of the separated fluorescent X-rays is X
An X-ray fluorescence analyzer for analyzing the sample by measuring with a X-ray detector, wherein the entrance window is provided in a part of the X-ray detector and guides the separated X-ray fluorescence into the X-ray detector. X-ray which detects the window member provided in the part in the soft X-ray region
There is provided an X-ray fluorescence analyzer formed from a substance having an absorption edge near the short wavelength side of a line.

In addition, according to the present invention, in order to achieve the above object, a core wire for detecting incident X-rays is provided in a housing filled with a detection gas, and a part of the housing has strength. What is claimed is: 1. An X-ray detector comprising an incident window for entering an X-ray to be measured therein, said window member having an absorption edge near a short wavelength side of fluorescent X-rays to be detected in a soft X-ray region. An X-ray analyzer formed from a material is provided.

According to the present invention, in the X-ray fluorescence analyzer and the X-ray analyzer described above, the window member is formed from a plurality of stacked layers, and each of the plurality of layers is formed by: Different fluorescent X in the soft X-ray region
It is also possible to form the X-ray detector from a substance having an absorption edge near the short wavelength side of the line, and it is preferable that the X-ray detector is an enclosed X-ray detector.

In addition, in the above-mentioned X-ray detector,
Substances having an absorption edge near the short wavelength side of X-rays are boron,
Selected from the group consisting of carbon, boron carbide, boron nitride, boron oxide, and carbon nitride, this material is formed as a thin film on the surface of a plate-like support member, and further, the plate-like support member is made of silicon. , Silicon oxide, or metal, and has a mesh-like opening at a position corresponding to the entrance window, and it is particularly preferable to use an enclosed X-ray detector. The X-ray incidence window applied to such an apparatus or detector is formed by depositing at least one substance having an absorption edge near the short wavelength side of fluorescent X-rays to be detected in the soft X-ray region by vapor deposition. Is preferred.

[0014]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. First,
FIG. 3 shows a schematic configuration of a fluorescent X-ray analyzer according to one embodiment of the present invention. In the drawing, a detection sample S is transported in a vacuum chamber 100 in the apparatus. The sample S is placed at a predetermined position by the apparatus, and the sample S is irradiated with X-rays XR from the X-ray tube 200. The fluorescent X-rays KX generated from the sample by this X-ray irradiation are transmitted through the vacuum chamber 1
The spectroscopic element (spectroscopy means) 350 provided in the spectroscopic chamber 300 which is adjacent to 00 and which is also kept in a vacuum, is spectrally separated, and then the separated fluorescent X-rays KX are, for example,
The intensity is measured by the X-ray detector 400 including a proportional counter, and the sample is analyzed.

The X-ray detector 400 is, for example, provided on one side surface of a highly-sealed cylindrical member (housing) 410 made of a metal member as shown in FIG.
For example, a slit-shaped X-ray incident window 420 is provided, and a so-called window member 430 is fixed so as to cover the window 420. As shown in FIG. 5, an X-ray detection gas G such as Ar or Ne is sealed inside the X-ray detector 400, and a central portion thereof is, for example, about 50 μm in diameter. A core wire 440 made of a Pt wire is stretched. In FIG. 5, the electrode 450
And +1200 to the core wire 440 via the resistor R.
A high voltage (HV) of about 1500 V is supplied.
X-ray (fluorescent X-ray KX) detected by the core wire 440
Is extracted as an electric signal via a condenser C, the amplitude of which is further amplified by an amplifier A at the subsequent stage, and the intensity is measured as a pulse signal by a pulse height analyzer (PHA). Part will be transferred.

Next, the window member 430 for covering the entrance window 420 of the X-ray detector 400 will be described in detail below with reference to FIGS. The window member 430 is supported by the support plate 431, for example, by an adhesive, or by pressing, caulking, caulking, or the like.
It is sealed and fixed to the entrance window 420.

First, FIG. 2 shows a window member 43 according to the present invention.
As is clear from the figure, a thin film 432 of a substance, which will be described in detail below, is formed on one surface of a plate-like (thin plate having a thickness of 0.5 mm) support plate 431. It becomes. The substantially central portion of the plate-shaped support plate 431 is formed in a so-called mesh shape in a region corresponding to a position and a shape corresponding to the entrance window 420 of the X-ray detector 400, and thereby, a mesh is formed. An opening 433 in the shape of a circle is formed. The opening is, for example, in the form of a fine mesh having an aperture ratio of 80%, but is not necessarily limited to the mesh-like one, and a substantially central portion of the plate-shaped support plate 431 is formed in the entrance window 420. Cut to the corresponding shape,
Alternatively, it may be a simple opening formed by punching. However, from the viewpoint of improving the mechanical strength of the window member 430, it is preferable to form the mesh-shaped opening as described above.

Next, the selection of the material of the thin film 432 in the window member 430 according to the present invention will be described below with reference to FIG. In general, pure organic and inorganic substances are converted into X-rays (including fluorescent X-rays) passing through the inside.
And has a characteristic of absorbing X-rays, as shown by the transmittance on the vertical axis of the graph of FIG. That is, the larger the wavelength of the transmitted X-ray, the higher the absorption (that is, the lower the transmittance). And, the tendency is, in particular, a wavelength of about 1 to 10 nm.
In the soft X-ray region, which has conventionally caused a decrease in the detection efficiency of the X-ray detector 400 in the soft X-ray region.

Although the organic and inorganic substances differ depending on the substance, as shown in FIG. 1, the transmittance gradually increases from the characteristic of gradually decreasing the transmittance to the maximum value (MA).
X), and some substances exhibit this absorption edge in the soft X-ray region (wavelength: about 1 to 10 nm).

Therefore, in the present invention, the substance of the thin film 432 forming the window member 430 is selected based on the above findings. That is, as shown in FIG.
Among the X-ray wavelengths (detected wavelengths) detected by the X-ray detector 400 of the X-ray fluorescence analyzer, particularly, the detected wavelengths in the soft X-ray region (wavelength: about 1 nm to 10 nm) are:
The transmittance of the material forming the window member is located near the long wavelength side (right side of the horizontal axis of the graph in the drawing), in other words, near the short wavelength side of the wavelength to be detected, which is unique to the substance. The substance is selected as the thin film material of the window member so that the absorption edge showing the maximum value of the characteristic is located. Thereby, as is clear from the figure, even for a desired X-ray wavelength in the soft X-ray region, the incident window of the X-ray detector has
Sufficient permeability for the detection is obtained. In addition,
Specific examples of the substance having such properties include a substance group consisting of boron, carbon, boron carbide, boron nitride, boron oxide, and carbon nitride, and one substance is selected from these. In this specification, such a substance is simply referred to as a substance having an absorption edge near a short wavelength side of fluorescent X-rays detected in a soft X-ray region.

The plate-like support plate 431 constituting the window member 430 may be made of, for example, silicon or silicon in consideration of a mesh opening 433 formed at the center thereof.
Thin plates of various metals (alloys) including silicon oxide or stainless steel are preferable from the viewpoint of ease of processing. The support plate 431 has a thin film 432 on its surface.
Any material can be used as long as the material can be formed, and it is not necessarily limited to the above-described members.

Next, the window member 4 according to the present invention described above.
Thirty specific embodiments will be described in detail below.

(Example 1) C-Kα detection window member Here, C-Kα in the soft X-ray region (wavelength: 4.4)
The window member used for the detection of 7 nm) will be specifically described with reference to FIG.

First, a substance having an absorption edge near the short wavelength side of the fluorescent X-ray wavelength of C-Kα (wavelength: 4.47 nm) is selected. Specific candidates include carbon. Therefore, this carbon is mirror-polished on both sides to a thickness of about 0.5.
mm Si wafer is prepared (see FIG. 6A), and on one surface (upper surface) thereof, for example, by a sputter deposition method.
A single-layer film having a thickness of about 500 nm is formed (FIG. 6).
(B)).

On the other hand, on the other surface (lower surface) of the Si wafer, a mesh resist pattern is formed by pattern transfer (see FIG. 6C), and then a part of the Si is wet-etched by wet etching. (See FIG. 3D). Further, the transferred resist pattern is removed, and a mesh-shaped opening 433 is formed in the plate-shaped support plate 431.
The window member 430 is completed (FIG. 6).
(E)).

(Example 2) B-Kα, C-Kα, NK
α detection window member Here, B-Kα (wavelength: 6.7) in the soft X-ray region
6 nm), C-Kα (wavelength: 4.47 nm), and N
The window member used for detecting -Kα (wavelength: 3.16 nm) will be specifically described with reference to FIGS.

First, B-Kα, C-Kα, N-Kα
A substance having an absorption edge near the short wavelength side of the fluorescent X-ray wavelength is selected. Here, as a specific candidate, as a substance for BKα ray and NKα ray, for example, boron nitride is used, and as a substance for C—Kα ray, carbon is mentioned again.

First, a specific manufacturing method of this window member is as follows.
Prepare a stainless steel sheet with a thickness of about 0.1 mm (Fig. 7
(A), a carbon film having a thickness of about 75 nm and a thickness of about 150 n
A boron nitride film having a thickness of m and a carbon film having a thickness of about 75 nm were formed again in this order (see FIG. 7B).

Thereafter, a mesh resist pattern is formed on the other surface (lower surface) of the stainless steel sheet by pattern transfer (see FIG. 7C), and then a part of the stainless steel sheet is mesh-etched by wet etching. (See FIG. 7D), and further, the transferred resist pattern is removed to form a mesh-shaped opening 433 in the plate-shaped support plate 431, thereby completing the window member 430 (FIG. 7). (E) is the same as in the first embodiment.

In the second embodiment, a film made of a material having a three-layer structure of a carbon film, a boron nitride film, and a carbon film is formed on a stainless steel sheet. It is not limited to only such a layer structure,
For example, a two-layer structure of a carbon film and a boron nitride film, or a two-layer structure of a boron nitride film, that is, a four-layer structure is also possible. It will be possible to select as appropriate.

Subsequently, the window members obtained in Examples 1 and 2 which were obtained as described above, were mounted on an enclosed X-ray detector, and their X-ray transmittances (particularly, transmission in a soft X-ray region) were measured. The results of measurement of the ratio are shown in FIGS. 8 and 9 attached.

As is apparent from FIG. 8, the window member according to the first embodiment has a wavelength to be measured (detected wavelength) C-Kα.
Good transmittance is obtained in a wider region with a longer wavelength (wavelength: a region of 4.47 nm or more), and particularly, C-Kα
At the line wavelength (4.47 nm), about 0.65 (65%)
It can be seen that a very high transmittance was obtained.

As is apparent from FIG. 9, the window member according to the second embodiment has a plurality of wavelengths to be measured (detected wavelengths) N-Kα, C-Kα, and B-Kα (each having a wavelength:
It can be seen that good transmittance can be obtained in a wider wavelength region centered on 3.16 nm, 4.47 nm, wavelength: 6.76 nm). More specifically, compared to a conventional entrance window configured by coating a mylar film with aluminum and pasting it to a mesh support plate having an aperture ratio of 80%, for example, B-Kα is twice or more as high. The transmittance is obtained (X-ray transmittance of the conventional entrance window: about 0.2 (2
0%), and the X-ray transmittance of the entrance window of the present invention (Example 2): about 0.5 (50%).

Further, an airtightness test using a helium leak detector was performed on the sealed X-ray detector having the window members according to the first and second embodiments. As a result, about 1
The helium leak amount at the pressure difference of the atmospheric pressure is 10 ⁻⁹ Pa ·
m ³ / s or less, that is, it was found to have sufficient airtightness as a window member for an enclosed X-ray detector.

In the window members according to the first and second embodiments, the X-ray to be detected is placed on a support plate 431 made of a thin plate of various metals (alloys) including silicon, silicon oxide, or stainless steel. By forming a material having an absorption edge near the short wavelength side of the wavelength of
The strength of the line entrance window 430 as a window member is ensured.
However, when the window member of the present invention is used for a detector other than the above-mentioned enclosed type, for example, a gas flow type X-ray detector, the wavelength of the X-ray to be detected is once reduced on the surface of the support plate 431. Forming a film having a material having an absorption edge near the wavelength side,
Thereafter, by removing and peeling the support plate 431, it is possible to obtain a window member having a film structure made of only such a substance.

Further, an X-ray detector provided with the above-described window member according to the present invention at its entrance window, and the X-ray detector
According to the X-ray fluorescence spectrometer equipped with the X-ray detector, the wavelength
Not only in the so-called hard X-ray region of 1 nm or less, but also in the so-called soft X-ray region (1 nm to
10 nm), it is possible to measure the fluorescent X-rays from the sample, and it is possible to remarkably improve the performance as a fluorescent X-ray analyzer (for example, measurement with one X-ray detector is possible). Since the number of wavelengths of the fluorescent X-rays increases, the analysis speed as an analyzer can be improved without increasing the number of detectors). In particular, the window member having the support plate according to the first and second embodiments is excellent in mechanical strength and airtightness, and is most suitable as a window member of an encapsulated X-ray detector. Thereby, the structure and handling of the X-ray fluorescence analyzer can be simplified as well as the above performance can be improved.

Further, according to the window member of the present invention, the selectively selected material such as boron, carbon, boron carbide, boron nitride, boron oxide, carbon nitride, etc.
Compared to the polymer film (for example, polyimide film) used for detecting the line region, it is thermally stable, and is sufficient in the baking process required in the manufacturing process of the X-ray detector (counter tube). Particularly, it is advantageous in a vacuum X-ray fluorescence analyzer for performing analysis in a vacuum state of a measurement chamber.

[0038]

As is apparent from the above detailed description, according to the present invention, the range detectable by the X-ray detector is not limited to the short wavelength hard X-ray region but also to the long wavelength soft X-ray. By expanding to an area, it becomes possible to improve the analysis performance and speed of the fluorescent X-ray analyzer and to reliably manufacture an X-ray entrance window for realizing such excellent effects.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of selection of a substance in a window member constituting an entrance window of an X-ray detector according to the present invention.

FIGS. 2A and 2B are a top view and a bottom view, respectively, showing a detailed structure of a window member of the above-mentioned entrance window.

FIG. 3 is a diagram showing a schematic configuration of a fluorescent X-ray analyzer according to one embodiment of the present invention.

FIG. 4 is a perspective view showing an example of the structure of an X-ray detector which is a feature of the X-ray fluorescence analyzer of the present invention.

FIG. 5 is a block diagram showing an example of the internal structure of the X-ray detector and its related circuits.

FIG. 6 is a process explanatory view illustrating a method for manufacturing the window member of the entrance window according to the first embodiment of the present invention.

FIG. 7 is a process explanatory view illustrating a method for manufacturing a window member of an entrance window according to a second embodiment of the present invention.

FIG. 8 is a diagram showing a graph of characteristics (X-ray transmittance) at the entrance window according to the first embodiment of the present invention.

FIG. 9 is a diagram showing a graph of characteristics (X-ray transmittance) at an entrance window according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 100 vacuum chamber 200 X-ray tube 300 Spectroscopic chamber 350 Spectroscopic element (spectroscopic means) 400 X-ray detector 410 Member of X-ray detector (housing) 420 X-ray incident window 430 Window member 431 Supporting member 432 Thin film layer 433 Mesh Opening

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Junji Fujimori 14-8 Akaojimachi, Takatsuki-shi, Osaka Rigaku Electric Industrial Co., Ltd. F-term (reference) 2G001 AA01 BA04 BA11 BA13 CA01 DA01 DA10 EA01 GA01 JA04 KA01 NA03 NA07 RA02 RA04 RA08 2G088 EE29 FF02 GG01 JJ08

Claims (10)

[Claims] 1. A sample placed in a sample chamber is irradiated with X-rays from an X-ray tube, and fluorescent X-rays generated from the sample are separated by spectral means, and the intensity of the separated fluorescent X-rays is determined by an X-ray. What is claimed is: 1. An X-ray fluorescence analyzer for analyzing said sample by measuring with a detector, wherein said X-ray fluorescence analyzer is provided in a part of said X-ray detector.
A fluorescent member, characterized in that a window member provided in an incident window for guiding a ray into the X-ray detector is formed of a substance having an absorption edge near a short wavelength side of fluorescent X-rays detected in a soft X-ray region. X-ray analyzer. 2. The X-ray fluorescence analyzer according to claim 1, wherein the window member is formed of a plurality of stacked layers, and each of the plurality of layers is formed of a soft X-ray. An X-ray fluorescence analyzer characterized by being formed from a substance having an absorption edge near the short wavelength side of different X-ray fluorescence in the region. 3. The X-ray fluorescence spectrometer according to claim 1, wherein the X-ray detector is an enclosed X-ray detector. 4. A core line for detecting incident X-rays is provided in a casing filled with a detection gas, and an entrance window for entering X-rays for measuring intensity into a part of the casing is provided. X
An X-ray analyzer, wherein the window member is formed of a substance having an absorption edge near a short wavelength side of fluorescent X-rays to be detected in a soft X-ray region. 5. The X-ray detector according to claim 4, wherein the window member is formed of a plurality of stacked layers, and each of the layers forming each of the layers has a different short-wavelength X-ray wavelength. An X-ray detector formed from a substance having an absorption edge near a side. 6. X according to claim 4 or claim 5.
In the X-ray detector, the substance having an absorption edge near the short wavelength side of the X-ray is selected from the group consisting of boron, carbon, boron carbide, boron nitride, boron oxide, and carbon nitride. Line detector. 7. X according to claim 4 or claim 5.
The line detector further includes a plate-shaped support member, and the substance having an absorption edge near a short wavelength side of the X-ray to be detected is formed as a thin film on the surface of the plate-shaped support member. An X-ray detector comprising: 8. The X-ray detector according to claim 7, wherein the plate-shaped support member is made of any one of silicon, silicon oxide, and metal, and is located at a position corresponding to the entrance window. X has a mesh-shaped opening.
Line detector. 9. The X-ray detector according to claim 7, wherein said X-ray detector is an enclosed X-ray detector. 10. An X-ray detecting part of a housing of an X-ray detector.
A method for manufacturing an X-ray incident window provided for entering a line, wherein at least one substance having an absorption edge near a short wavelength side of fluorescent X-rays to be detected in a soft X-ray region is formed by vapor deposition. A method for manufacturing an X-ray incidence window, characterized by being formed by: