JP2003294659A - X-ray analysis apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve flexibility larger than a conventional embodiment with regard to an arrangement location of a dispersive crystal and a detector, maintain high sensitivity and implement multiple element analysis without moving the dispersive crystal or the detector. <P>SOLUTION: When an electron beam 1 irradiates a sample 2, X rays are radiated from an element at a location irradiated by the electron beam 1. The X rays are collected by an X-ray collection means 3 and enter into an entrance face of the dispersive crystal 4. Only the X ray meeting a diffraction condition is diffracted and enters into a light receiving face of a CCD camera 5. The X ray entering into the light receiving face of the CCD camera 5 is picked up by the CCD camera 5. An image data picked up by the CCD camera 5 is processed by a predetermined process of a process means 6 and a spectrum is created. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray analyzer for analyzing characteristic X-rays emitted from a sample, which is provided with a wavelength-dispersive X-ray dispersive crystal, and more particularly to moving the dispersive crystal and X-ray detecting means. The present invention relates to an X-ray analysis apparatus that can perform multi-element analysis without using the element.

[0002]

2. Description of the Related Art Various types of X-ray analyzers for analyzing elements contained in a sample are known. One of them is a wavelength dispersive X-ray spectroscopic crystal (hereinafter, simply referred to as a spectroscopic crystal). A device using (referred to as) is known. For example, in a so-called electron probe microanalyzer (EPMA), a sample is irradiated with an electron beam, and characteristic X-rays (hereinafter, simply referred to as X-rays) emitted from the sample at that time are diffracted by a dispersive crystal. Then, the diffracted X-ray is detected by the detector.

[0003]

However, as is well known, in the conventional X-ray analyzer using the dispersive crystal, the X-ray source of the sample, the dispersive crystal, and the detector are arranged on the Rowland circle. Therefore, there is a problem that there is no degree of freedom in the arrangement position of the dispersive crystal and the detector.

Further, in this type of conventional X-ray analyzer,
Since a certain distance is required between the X-ray generation source of the sample and the dispersive crystal, the X-rays emitted from the sample are diffused,
There is also a problem in that the sensitivity tends to deteriorate because only part of the X-rays emitted from the sample is incident on the dispersive crystal.

Further, this type of conventional X-ray analyzer has the following problems. When the positions of the X-ray generation source of the sample, the dispersive crystal, and the detector are determined to be one, only one type of X-ray is detected by the detector. The detector and the detector must be interlocked to move on the Roland circle, but the dispersive crystal and the detector must be moved with high accuracy. Because
This is because the detected X-ray is determined by the positional relationship among the X-ray generation source of the sample, the dispersive crystal, and the detector.

However, in order to move the Roland circle with high accuracy by interlocking the dispersive crystal and the detector, a high-precision drive mechanism is required, which causes a problem of high cost. There is also a problem in that it takes time to measure because it takes time to measure. Further, there is a problem that the measurement accuracy is deteriorated due to a mechanical error caused by the movement of the dispersive crystal and the detector.

As described above, the conventional X using the dispersive crystal is used.
The line analysis device has various problems.

Therefore, according to the present invention, the arrangement position of the dispersive crystal and the detector has a wider degree of freedom than the conventional one, the sensitivity can be kept high, and the multi-element analysis is performed without moving the dispersive crystal or the detector. It is an object of the present invention to provide an X-ray analyzer capable of performing the above.

[0009]

In order to achieve the above object, an X-ray analyzer according to claim 1 is an X-ray condensing means for condensing characteristic X-rays emitted from a sample, and a characteristic X-ray. A wavelength-dispersive X-ray dispersive crystal having an incident surface on which rays are incident is curved in a concave shape and diffracting the characteristic X-rays condensed by the X-ray condensing means, and the wavelength-dispersive X-ray dispersive crystal. X-ray detecting means for making the characteristic X-rays incident on the light receiving surface are provided. An X-ray analyzer according to claim 2 is characterized in that, in claim 1, the X-ray condensing means, the wavelength dispersive X-ray dispersive crystal, and the X-ray detecting means are fixedly arranged. To do. The X-ray analysis apparatus according to claim 3 is
In Claim 1 or 2, The said X-ray condensing means is an X-ray lens, It is characterized by the above-mentioned. According to a fourth aspect of the present invention, in the first or second aspect, the X-ray focusing means is a polycapillary. According to a fifth aspect of the present invention, in the first or second aspect, the X-ray detecting means is a CCD camera.
According to a sixth aspect of the present invention, in the first or second aspect, the X-ray detecting means is a one-dimensional X-ray detector.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of an X-ray analysis apparatus according to the present invention. In the figure, 1 is an electron beam, 2 is a sample, 3 is an X-ray condensing means, 4 is a dispersive crystal, 5
Is an X-ray detection means, 6 is a processing means, and P is an X-ray generation source.

The X-ray focusing means 3 is an X-ray generation source P for the sample 2.
This is for preventing the diffusion of X-rays emitted from the X-ray analyzer and allowing more X-rays to be incident on the dispersive crystal 4, and is fixedly arranged in the X-ray analyzer. As the X-ray condensing means 3, an X-ray lens or a polycapillary can be used. Since the X-ray lens and the polycapillary are well known, detailed description will be omitted. Then, as will be apparent from the later description, by using this X-ray focusing means 3, the sensitivity can be improved as compared with the conventional one.

The dispersive crystal 4 is for separating incident X-rays, and the incident surface on which the X-rays are incident is curved in a concave shape (hereinafter, simply referred to as "curvature"). This dispersive crystal 4 is also fixedly arranged in the X-ray analysis apparatus. Dispersive crystal 4
The curvature of curvature of the incident surface of the crystal is the crystal surface spacing (spacing) d, the light receiving area of the X-ray detecting means 5 described later, the desired number of analysis elements, and the X-ray focusing means 3 and the dispersive crystal 4 and X. It may be determined in consideration of the positional relationship between the line detection means 5 and the like.

The X-ray detecting means 5 detects the X-rays dispersed by the dispersive crystal 5, and the X-ray detecting means 5 is also fixedly arranged in the X-ray analyzer. The X-ray detecting means 5 has a sensitivity in the X-ray region.
-Dimensional CCD camera or position sensitive proportional counter (PSPC: positi)
A well-known one-dimensional X-ray detector such as an on sensitive proportional counter) can be used. Here, X
A CCD camera is used as the line detection means 5,
It will be referred to as "CCD camera 5". The case of using the one-dimensional X-ray detector will be described later.

The processing means 6 creates a spectrum based on the image obtained by the CCD camera 5.
This process will be described later.

Since this X-ray analysis apparatus has the above-described structure, when the sample 2 is irradiated with the electron beam 1, X-rays are emitted from the elements near the irradiation position of the electron beam 1. Then, the X-rays emitted from the sample 2 are condensed by the X-ray condensing means 3 and are incident on the incident surface of the dispersive crystal 4, and only the X-rays satisfying the diffraction condition are diffracted and the light receiving surface of the CCD camera 5 is diffracted. Incident on. This is X-ray spectroscopy. And C
X-rays incident on the light receiving surface of the CD camera 5 are CCD cameras 5.
Is imaged by. The data of the image captured by the CCD camera 5 is subjected to a predetermined process by the processing means 6 to create a spectrum.

Here, the provision of the X-ray focusing means 3 is as follows.
As described above, it is important in the sense of improving sensitivity. This will be described below with reference to FIG. In FIG. 2, an X-ray lens is used as the X-ray focusing means 3.

The X-rays emitted from the X-ray generation source P of the sample 2 have a spread as shown in FIG. Now, considering the X-rays emitted in the directions indicated by A and B in FIG. 2, the X-rays A and B are broken lines in FIG. 2 when the X-ray focusing means 3 is not provided. Go straight as indicated by A'and B '. In the case shown in FIG. 2, these X-rays A ′ and B ′ do not enter the incident surface of the dispersive crystal 4. However, when the X-ray focusing means 3 is provided as shown in FIG. 2, the X-rays A and B are the X-ray focusing means 3, in this case X-rays, as shown by the chain lines A ″ and B ″ in FIG. The light is refracted by the linear lens and enters the incident surface of the dispersive crystal 4.

As described above, by disposing the X-ray condensing means 3 between the sample 2 and the dispersive crystal 4, more X-rays of the X-rays emitted from the sample 2 are incident on the incident surface of the dispersive crystal 4. Can be incident on. As a result, the utilization efficiency of the X-rays emitted from the sample 2 is improved and the sensitivity is improved.

Although the case where the X-ray lens is used as the X-ray focusing means 3 has been described above, the same effect can be obtained when the polycapillary is used as the X-ray focusing means 3.

Further, it is important to bend the incident surface of the dispersive crystal 4 from the viewpoint of increasing the number of elements that can be analyzed without moving the dispersive crystal 4 and the like. This will be described below with reference to FIGS. 3 and 4. In FIGS. 3 and 4,
In order to show a comparison between the case where the incident surface of the dispersive crystal is curved and the case where it is not curved, a polycapillary is used as the X-ray condensing means 3, and X emitted from the X-ray generation source P of the sample 2 is used. It is assumed that the lines are incident on the dispersive crystal 4 as parallel rays by a polycapillary. 3 and 4, only the X-ray generation source P is shown for the sample 2 and CC
For the D camera 5, only the light receiving surface Q is shown.

FIG. 3 shows a case where the dispersive crystal 4 is a flat plate, and the X-rays emitted from the X-ray generation source P are X-ray focusing means 3.
Since the light rays are parallel rays, the incident angle on the dispersive crystal 4 is a constant angle θ. However, as is well known, the diffraction condition by the dispersive crystal differs depending on the energy of the X-ray, more specifically, the wavelength of the X-ray. Therefore, as shown in FIG. 3, when the incident angle is θ, the diffraction condition is satisfied. There is only one X-ray even if there is such an X-ray, and only one X-ray that satisfies this diffraction condition is diffracted by the dispersive crystal 4 as shown in FIG. 3 and is incident on the light-receiving surface Q of the CCD camera 5. Will be done.

In other words, when a flat dispersive crystal is used, it can be analyzed if the disposition of the dispersive crystal 4 is determined as one.
Since there is only one line, therefore, in order to perform multi-element analysis, it is necessary to rotate the dispersive crystal 4 as shown by arrows a and b in FIG. 3, but this achieves the above object. You cannot do it.

On the other hand, when the incident surface of the dispersive crystal 4 is curved, as shown in FIG. 4, even if the incident X-rays are parallel rays, they are incident on the incident surface of the dispersive crystal 4. The angle depends on the incident position. That is, in FIG. 4, the incident angles α, β and γ are different from each other. Therefore, not only one X-ray satisfies the diffraction condition, but also a plurality of X-rays satisfy the diffraction condition. Actually, when the positional relationship between the X-ray generation source P and the X-ray condensing means 3 and the dispersive crystal 4 was determined by using a dispersive crystal having a curved incident surface, the incident angle was 13 ° to 39 °.
It was in the range of °.

As described above, when a dispersive crystal having a curved incident surface is used, it is possible to satisfy a plurality of X-ray diffraction conditions, so that multi-element analysis can be performed even with the dispersive crystal 4 fixed. It will be possible.

The above description is for the case where a polycapillary is used as the X-ray converging means 3, but the same applies when an X-ray lens is used as the X-ray condensing means 3. However, X
When a line lens is used, the X-rays do not always become parallel rays, and when the X-rays do not become parallel rays, the incident angle of the flat crystal to the incident surface of the dispersive crystal is Since it depends on the incident position, a plurality of X-rays may satisfy the diffraction condition. However, when a dispersive crystal having a curved incident surface is used, the incident angle can be made wider, so that the diffraction condition can be satisfied for a larger number of X-rays.

As described above, the use of the X-ray condensing means 3 and the use of the dispersive crystal having a curved incident surface are very important items for achieving the above object.

Next, the process of creating a spectrum based on the image taken by the CCD camera 5 will be described.

To construct this X-ray analysis apparatus, it is determined what kind of X-ray focusing means 3 is used.
Specifically, for example, what X-ray lens or polycapillary is used is determined. By this, X
The light collecting characteristic of the line light collecting means 3 is determined. Further, the configuration of the dispersive crystal 4 is determined. Specifically, how the curvature of the reflection surface is curved, what kind of crystal plane spacing is used, and the size such as length and width are determined. Further, what kind of CCD camera 5 is used, specifically, the image pickup characteristics such as the size of the light receiving surface and the number of pixels are determined. Then, the positional relationship between the X-ray generation source P, the X-ray focusing means 3, the dispersive crystal 4, and the CCD camera 5 is determined. Here, it is assumed that the arrangement positional relationship includes the relationship between the mutual distance and the three-dimensional angle. For example, in the case of the positional relationship between the dispersive crystal 4 and the CCD camera 5, the distance between the dispersive crystal 4 and the CCD camera 5, and the CCD
It also includes a three-dimensional angle relationship such as what angle the light receiving surface of the camera 5 should be.

When these are determined, the range of the incident angle to the incident surface of the dispersive crystal 4 is known, and the diffraction condition of the X-ray of each element in the dispersive crystal 4 is known. It can be seen whether the line is diffracted by the dispersive crystal 4 and is incident on the light receiving surface of the CCD camera 5. That is, it is possible to know what element can be analyzed.

The structure of the dispersive crystal 4, the X-ray diffraction conditions on the incident surface of the dispersive crystal 4, and the positional relationship between the X-ray generation source P, the X-ray focusing means 3, the dispersive crystal 4, and the CCD camera 5 are set. From this, it is possible to know what area of the light receiving surface of the CCD camera 5 the X-ray of which energy is incident on. This can be obtained by geometric theoretical calculation, or can be obtained by actually carrying out an experiment using a standard sample in which the elements contained in advance and their concentrations are known. Particularly, in the latter case, not only which energy X-ray is incident on what area of the CCD camera 5 but also the correspondence relationship between the integrated value of the luminance of the pixels in that area and the actual concentration of the element. It is effective because it can be calibrated.

From the above, as the processing performed by the processing means 6, for example, the image picked up by the CCD camera 5 is scanned and read out, the image data is temporarily stored in the memory, and the brightness is determined in any area. By determining whether there is any, it is possible to detect what energy the X-ray has entered, that is, what element is contained in the sample 2. The intensity of each X-ray incident on the light-receiving surface of the CCD camera 5 is detected by integrating the pixel values of pixels included in the area corresponding to the X-rays, that is, the brightness value.

By the above processing, the energy and intensity of the X-rays emitted from the X-ray generation source P of the sample 2 are detected.

Then, the processing means 6 creates a spectrum by plotting the energy and intensity of the X-ray detected by the above-mentioned processing, with the horizontal axis as the X-ray energy and the vertical axis as the X-ray intensity. In addition, it is natural that the process of removing the background noise is performed before the process of creating the spectrum described above.

The case where a CCD camera is used as the X-ray detecting means 5 has been described above, but a case where a one-dimensional X-ray detector, a so-called X-ray line sensor is used as the X-ray detecting means 5 will be additionally described.

When a one-dimensional X-ray detector is used as the X-ray detecting means 5, the arrangement is such that the longitudinal direction of the light receiving surface 8 is in the direction in which the X-ray energy is dispersed, as shown in FIG. To By doing so, it becomes possible to perform multi-element analysis. This one-dimensional X-ray detector is also fixedly arranged.

However, when a one-dimensional X-ray detector is used as the X-ray detecting means 5, only a part of the X-rays diffracted by the dispersive crystal 4 can be detected, so that the X-ray can be detected once. The intensity of X-ray cannot be measured with high precision by measurement. Therefore, in this case, as is well known, the X-ray source P
It is necessary to fix, and measure many times to perform the process of integrating the intensities detected by the one-dimensional X-ray detector.

As described above, according to this X-ray analyzer, there is no restriction that the X-ray source, the dispersive crystal and the X-ray detector have to be arranged on the Rowland circle as in the conventional case. Therefore, the X-ray generation source P, the dispersive crystal 4, and the X-ray detection means 5 have a greater degree of freedom than the conventional arrangement.

Further, the X-ray condensing means 3 is used to generate an X-ray source P.
Since the X-rays emitted from the light-collecting device are condensed and made incident on the dispersive crystal 4, more X-rays can be made incident on the dispersive crystal 4, and the sensitivity can be improved.

Further, since the dispersive crystal 4 having a curved incident surface is used, the incident angle of the X-ray can be widened, and as a result, the dispersive crystal 4 and / or the X-ray detecting means 5 can be moved. It is possible to carry out multi-element analysis without using it.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an X-ray analysis apparatus according to the present invention.

FIG. 2 is a diagram for explaining that the sensitivity can be improved by the X-ray focusing means 3.

FIG. 3 is a diagram for explaining a problem when a flat dispersive crystal is used as the dispersive crystal 4.

FIG. 4 is a diagram for explaining that the number of elements that can be analyzed can be increased by moving the incident surface of the dispersive crystal 4 without moving the dispersive crystal 4 and the like.

5 is a diagram for explaining the arrangement when a one-dimensional X-ray detector is used as the X-ray detection means 5. FIG.

[Explanation of symbols]

1 ... Electron beam, 2 ... Sample, 3 ... X-ray condensing means, 4 ... Dispersion crystal, 5 ... X-ray detecting means, 6 ... Processing means, P ... X-ray generating source.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Miyuki Kanayama             3-12 Musashino, Akishima-shi, Tokyo Japan             Electronic Engineering Co., Ltd. F-term (reference) 2G001 AA03 BA05 CA01 DA08 DA09                       EA01 EA02 GA01 HA13 JA06                       KA01 NA30 SA02 SA29 SA30

Claims (6)

[Claims] 1. An X for collecting characteristic X-rays emitted from a sample.
A line condensing means; a wavelength dispersive X-ray dispersive crystal having an incident surface on which characteristic X-rays are incident curved in a concave shape and diffracting the characteristic X-rays condensed by the X-ray condensing means; An X-ray analysis device, comprising: an X-ray detection unit that causes a characteristic X-ray diffracted by a dispersive X-ray analysis crystal to enter a light receiving surface. 2. The X-ray analysis apparatus according to claim 1, wherein the X-ray focusing means, the wavelength dispersive X-ray dispersive crystal, and the X-ray detecting means are fixedly arranged. 3. The X-ray analysis apparatus according to claim 1, wherein the X-ray focusing means is an X-ray lens. 4. The X-ray analyzer according to claim 1, wherein the X-ray focusing means is a polycapillary. 5. The X-ray analyzer according to claim 1, wherein the X-ray detecting means is a CCD camera. 6. The X-ray analysis apparatus according to claim 1, wherein the X-ray detection means is a one-dimensional X-ray detector.