WO2021112079A1

WO2021112079A1 - X-ray fluorescence analysis device

Info

Publication number: WO2021112079A1
Application number: PCT/JP2020/044667
Authority: WO
Inventors: 肇二位
Original assignee: 株式会社堀場アドバンスドテクノ
Priority date: 2019-12-02
Filing date: 2020-12-01
Publication date: 2021-06-10
Also published as: JP7377890B2; JPWO2021112079A1

Abstract

In order to provide an X-ray fluorescence analysis device in which the influence of scattered X-rays is unlikely to appear in the output of a detector, the lower detection limit of X-ray fluorescence generated from light elements such as silicon (Si) is reduced, and it is thus possible to accurately measure the concentration thereof, an X-ray fluorescence analysis device (100) for analyzing a liquid sample (LS) containing a first element to be measured and a second element having a larger atomic number than the first element is provided with: an X-ray source (1) that emits first X-rays; a secondary target (3) that is excited by the first X-rays and generates second X-rays, said secondary target (3) being provided such that the second X-rays are incident on the liquid sample (LS); a detector (6) for detecting X-ray fluorescence generated by the second X-rays incident on the liquid sample (LS); and a concentration calculator (7) that uses the output of the detector (6) as a basis to detect the concentration of the first element in the liquid sample (LS), said X-ray fluorescence analysis device (100) being configured so that a center of irradiation which is the intersection of the irradiation optical axis (LA) of the second X-rays with the sample surface (SP) of the liquid sample (LS) and a visual field center which is the intersection of the detection optical axis (DA) of the detector (6) with the sample surface (SP) are separated in the sample surface (SP).

Description

X-ray fluorescence analyzer

The present invention relates to a fluorescent X-ray analyzer capable of measuring the concentration of an element contained in a liquid sample.

In wet etching of a nitride film in a semiconductor manufacturing process, it is known that the silicon concentration in phosphoric acid affects the etching rate. Therefore, the silicon concentration in phosphoric acid is measured, and the quality control of phosphoric acid is performed.

Conventionally, the silicon concentration in phosphoric acid has been measured by, for example, the ion-selective electrode method (see Patent Document 1). In this method, since it is necessary to cool the phosphoric acid to a predetermined temperature, it is difficult to measure the silicon concentration in the phosphoric acid circulating at a high temperature in the etching control device in-line. In addition, since this measurement method has a problem that running is high, a measurement method that is easier to use is required.

By the way, the use of fluorescent X-ray analysis to measure the silicon concentration in phosphoric acid has not been industrially attempted so far.

This is because the intensity of fluorescent X-rays generated by exciting light elements such as silicon (Si) is lower than that of heavy elements, and the energy is low, so the degree of attenuation by the atmosphere is large. This is because it is difficult to quantitatively analyze silicon because the background effect of scattered X-rays generated at the same time as fluorescent X-rays is large on the output. Further, in fluorescent X-ray analysis using a spectroscopic crystal, it is difficult to accurately measure the concentration because the driving unit that drives the spectroscopic crystal and the spectroscopic crystal itself are affected by temperature by high-temperature phosphoric acid. In addition, if you try to select the energy of the fluorescent X-ray to be measured by the filter, the detected intensity will decrease, so it is suitable for fluorescent X-ray analyzers of light elements such as silicon (Si). Absent.

Japanese Unexamined Patent Publication No. 2016-6434

The present invention has been made in view of the above-mentioned problems, and the influence of scattered X-rays is less likely to appear on the output of the detector, and fluorescence X generated by exciting a light element such as silicon (Si) is generated. It is an object of the present invention to provide a fluorescent X-ray analyzer capable of lowering the lower limit of detection of a line and accurately measuring its concentration.

That is, the fluorescent X-ray analyzer according to the present invention is a fluorescent X-ray analyzer that analyzes a liquid sample containing a first element to be measured and a second element having a larger atomic number than the first element. The X-ray source that emits the first X-ray and the second X-ray that is excited by the first X-ray to generate the second X-ray are provided so that the second X-ray is incident on the liquid sample. The concentration of the first element in the liquid sample is calculated based on the next target, a detector that detects fluorescent X-rays generated in the liquid sample excited by the second X-ray, and the output of the detector. The irradiation center, which is the intersection of the second X-ray irradiation optical axis with respect to the sample surface of the liquid sample, and the visual field center, which is the intersection of the detection optical axis of the detector with respect to the sample surface. However, it is characterized in that it is configured to be separated in the sample plane.

In such a case, since the detector has the field of view centered at a portion deviated from the irradiation center on the sample surface, the intensity of the scattered X-rays of the second X-ray generated at the irradiation center is large. The component in the scattering direction can be made difficult to enter the field of view of the detector. On the other hand, since the fluorescent X-rays generated at the irradiation center are uniformly emitted in all directions, the amount of fluorescent X-rays incident in the field of view of the detector is scattered X-rays even if the irradiation center and the field center are shifted. Does not decrease compared to. Therefore, the influence of scattered X-rays on the background on the output of the detector can be reduced, and the lower limit of detection of fluorescent X-rays can be lowered. From these facts, even the intensity of fluorescent X-rays generated from a light element such as silicon (Si) can be measured without being buried in background noise.

As a configuration suitable for performing fluorescent X-ray analysis on the liquid sample, an X-ray permeable film that comes into contact with the liquid sample and forms a sample surface is further provided, and the second X-ray passes through the X-ray permeable film. Anything may be used as long as it is configured to irradiate the liquid sample. In such a case, the X-ray tube, the secondary target, and the detector and the measurement system can be arranged under the liquid sample to perform fluorescent X-ray analysis. Even if the liquid sample evaporates, the vapor does not affect the measurement system. Therefore, the configuration is particularly suitable when the liquid sample has a risk of deterioration of the measurement system due to vapor such as phosphoric acid. Further, when the measurement system is arranged above the liquid sample and a film or the like is provided to prevent the steam of the liquid sample, bubbles are generated between the liquid sample and the film, which hinders fluorescent X-ray analysis. There is a possibility that extra scattering may occur, but if the liquid sample is analyzed from below via the X-ray transmission film, such a problem can be prevented from occurring in the first place.

In order to achieve a thinness suitable for fluorescent X-ray analysis using the X-ray permeable membrane even when the liquid sample is at a high temperature, and to maintain sufficient mechanical strength, the X-ray is used. The line-transmitting membrane may be formed of polyimide, aromatic polyetherketone, polyphenylene sulfide, aramid, graphene, or diamond dry carbon.

The scattered X-rays of the second X-ray generated in the liquid sample are less likely to be incident on the detector, and each device is densely packed, and the optical path length of the fluorescent X-rays generated in the liquid sample to reach the detector. In order to shorten the length so that the detection can be performed at a higher intensity and lower the lower limit of measurement, the irradiation optical axis of the first X-ray is orthogonal to the Z-axis and the Z-axis at the light source point of the X-ray source. When the axis forming the XZ plane parallel to the sample surface is the X-axis, the axis passing through the light source point of the X-ray source and being orthogonal to the X-axis and the Z-axis is the Y-axis, the secondary target is the said. It is sufficient that the target surface on which the first X-ray is incident is provided, and the target surface is inclined with respect to the XZ plane and also with respect to the YZ plane.

As a specific configuration example of the target surface, the target is such that the normal vector with respect to the target surface is (X, Y, Z) = (-1 / 2,1 / √2, −1 / 2). Examples thereof include those whose surfaces are inclined with respect to the XZ plane and the YZ plane.

In order to increase the ratio of fluorescent X-rays to scattered X-rays incident on the detector and further lower the detection lower limit, the detector includes a detection surface for detecting fluorescent X-rays, and the detection surface is an XZ plane. It suffices that the detection surface faces the X-ray source side while being inclined with respect to the X-ray source.

In order to generate fluorescent X-rays at a plurality of locations in the liquid sample and to increase the intensity of the fluorescent X-rays incident on the detector by about a plurality of times, the secondary targets are required to generate second X-rays separately. It may consist of a plurality of target elements arranged in.

As a specific configuration example in which the intensity of fluorescent X-rays generated in the liquid sample can be doubled while keeping the influence of scattered X-rays small on the X-rays detected by the detector, two target elements are used. , Those arranged so as to sandwich the detector.

Even if the first element is silicon (Si) and the second element is phosphorus (P), the fluorescence analyzer of the present invention can reduce the running cost as compared with the ion-selective electrode method. Moreover, the concentration of silicon (Si) can be accurately measured. In addition, the concentration of silicon (Si) can be measured in-line.

As a specific configuration example for efficiently capturing the fluorescent X-rays generated by the liquid material into the detector, the distance between the irradiation center and the visual field center is 3 mm or more and 10 mm or less.

As described above, according to the fluorescent X-ray analyzer of the present invention, since the irradiation center and the detection center are displaced on the sample surface, the intensity of the scattered X-rays generated on the sample surface is high. The direction in which the high component is contained makes it easy to deviate from the solid angle that can be detected by the detector, and the intensity of the fluorescent X-ray to be measured can be relatively increased. Therefore, since the background value at the output of the detector can be lowered, the lower limit of detection of fluorescent X-rays can also be lowered. Therefore, even fluorescent X-rays of light elements such as silicon (Si) can be sufficiently detected, and quantitative analysis can be performed.

The schematic perspective view which shows the fluorescent X-ray analyzer in one Embodiment of this invention. The schematic diagram of the structure of the fluorescent X-ray analyzer in the same embodiment. FIG. 6 is a schematic view of the fluorescent X-ray analyzer according to the same embodiment when viewed along the Z-axis direction. FIG. 6 is a schematic view of the fluorescent X-ray analyzer according to the same embodiment when viewed along the Y-axis direction. Schematic graph showing the peaks and absorption edges of fluorescent X-rays of phosphorus (P) and silicon (Si). The schematic diagram which shows the fluorescent X-ray analyzer in another embodiment of this invention.

100 ・・・ Fluorescent X-ray analyzer 1 ・・・ X-ray source 2 ・・・ Primary collimator 3 ・・・ Secondary target 4 ・・・ Secondary collimator 5 ・・・ X-ray transmission film 6 ・・・ Detector 7 ・・・ Concentration calculator

The fluorescent X-ray analyzer 100 according to the embodiment of the present invention will be described with reference to FIGS. 1 to 5. The fluorescent X-ray analyzer 100 measures, for example, the concentration of silicon (Si), which is an element contained in a high-temperature phosphoric acid solution used for wet etching of a nitride film in a semiconductor manufacturing process. For example, phosphoric acid is in a high temperature state of 100 ° C. to 300 ° C., and in this embodiment, it is a liquid sample LS having a temperature of about 160 ° C. or 160 ° C. In addition, silicon (Si) contained in phosphoric acid is a trace element present at a concentration of about 1/1000 to 1/10000 with respect to phosphorus (P). That is, in phosphoric acid, which is a liquid sample LS, the first element to be measured is silicon (Si), and the second element having an atomic number larger than that of silicon (Si) is phosphorus (P). That is, the fluorescent X-ray analyzer 100 of the present embodiment performs fluorescent X-ray analysis on a liquid sample containing a large amount of the second element having an atomic number larger than that of the first element by one. In the fluorescent X-ray analyzer 100 of the present embodiment, for example, a part of phosphoric acid circulating in the etching apparatus is sampled, and fluorescent X-ray analysis is performed in a liquid state without cooling to obtain a silicon (Si) concentration. Is used to measure. Therefore, in the fluorescent X-ray analyzer 100, only silicon (Si) is excited to derive fluorescent X-rays, and fluorescent X-rays are not excited from phosphorus (P), or silicon (Si) and phosphorus (P) are excited. ) Are both excited, but the amount of fluorescent X-rays generated from phosphorus (P) is small enough to have little effect on calculating the concentration of silicon (Si).

Specifically, as shown in FIGS. 1 to 4, the fluorescent X-ray analyzer 100 is in contact with the X-ray source 1, the primary collimator 2, the secondary target 3, the secondary collimator 4, and the liquid sample LS. It is provided with at least a permeable film 5, a detector 6, and a concentration calculator. In the following description, the Cartesian coordinates of the right-handed system are set with the Z-axis as the emission direction of the first X-ray emitted from the X-ray source 1 and the light source point of the X-ray source 1 as a reference, and are used in the description. That is, the axis that is perpendicular to the Z-axis through the light source point and forms a surface parallel to the sample surface SP of the liquid sample LS formed by the X-ray transmission film 5 is the X-axis, and the X-axis passes through the light source point. The axis orthogonal to the Z axis and the Z axis is set as the Y axis. In this embodiment, the sample plane SP and the XZ plane are horizontal planes, and the Y axis coincides with the vertical direction.

The X-ray source 1 emits the first X-ray, and emits X-rays having an energy different from the energy irradiated to the liquid sample LS. The fluorescent X-ray generated by irradiating the secondary target 3 with the first X-ray is used as the second X-ray to irradiate the liquid sample LS. The X-ray source 1 is, for example, a vacuum vessel 11 in which the inside is kept in a vacuum and a beryllium (Be) window is formed as an X-ray transmission window 12, and an electron beam source (not shown) provided in the vacuum vessel 11. And a primary target 13 in which electrons emitted from an electron beam source are incident and a first X-ray is generated.

The primary collimeter 2 limits the range of irradiation of the first X-ray to a predetermined range. That is, the primary collimator 2 limits the first X-ray emitted from the beryllium window into a cylinder having a predetermined radius extending along the Z axis.

The secondary target 3 is a block body including a target surface 31 on which the first X-rays are incident, and a liquid in which the second X-rays generated by the first X-rays incident on the target surface 31 are arranged above the secondary target 3. It is configured to be ejected onto the sample LS and the X-ray transmission film 5. Specifically, as shown in FIGS. 1, 3 and 4, the target surface 31 is inclined with respect to the XZ plane and the YX plane. In the present embodiment, the target surface 31 is on the XZ plane and the YZ plane so that the normal vector with respect to the target surface 31 is (X, Y, Z) = (-1 / 2,1 / √2, -1 / 2). On the other hand, it is inclined.

Further, the main energy of the second X-ray emitted from the secondary target 3 excites silicon (Si), which is the first element contained in the liquid sample LS, to generate the corresponding fluorescent X-ray, and the liquid. The second element phosphorus (P) contained in the sample LS is selected so as not to be excited and to generate fluorescent X-rays. That is, the energy of the absorption edge of silicon (Si), which is the first element, is E1, the energy of the absorption edge of phosphorus (P), which is the second element, is E2, and the energy of the second X-ray generated by the first X-ray on the target surface 31. When the energy peak is EP, the secondary target 3 is configured so as to satisfy E1 <EP <E2. In this embodiment, the secondary target 3 is formed of phosphorus (P) which is not a measurement target. Here, as shown in the graph of FIG. 5, the energy EP of the Kα ray, which is a fluorescent X-ray generated by the incident of the first X-ray on phosphorus (P), is smaller than the energy E2 at the absorption edge of phosphorus (P). , It is larger than the energy E1 at the absorption edge of silicon (Si). That is, since the energy at the absorption edge of a certain element is larger than the energy of the second X-ray generated by the incident of the first X-ray, the secondary target 3 is formed by the second element to be excluded in the liquid sample LS. By doing so, it is possible to prevent the liquid sample LS from emitting the fluorescent X-ray of the second element by the second X-ray generated by the secondary target 3.

As shown in FIGS. 1 to 4, the secondary collimator 4 limits the irradiation range and irradiation direction of the second X-ray generated by the secondary target 3 with respect to the sample surface SP. That is, the secondary collimator 4 defines the irradiation optical axis LA of the second X-ray in a predetermined direction.

The X-ray transmission film 5 is a film extending along a horizontal plane, and forms a sample surface SP in contact with the liquid sample LS on the upper surface thereof. The X-ray transmission film 5 is, for example, a resin film having a film thickness of μm, and is configured to suppress the attenuation of incident second X-rays and fluorescent X-rays generated in the liquid sample LS as much as possible. In the present embodiment, the X-ray transmission film 5 is formed of polyimide or aromatic polyetherketone. The second X-ray generated by the secondary target 3 penetrates through the X-ray transmission film 5 and penetrates into the liquid sample LS to a predetermined depth. Here, the predetermined depth is about several tens of μm to several hundreds of μm. As described above, the second X-ray incident on the liquid sample LS generates fluorescent X-rays for silicon (Si) contained in the liquid sample LS and also generates scattered X-rays at the same time. The X-ray permeable membrane 5 may be formed of polyphenylene sulfide, aramid, graphene, or diamond-like carbon.

The detector 6 detects fluorescent X-rays generated in the liquid sample LS, and the detection surface 61 is arranged so as to be parallel to the sample surface SP. That is, the detection optical axis DA of the detector 6 is provided so as to be perpendicular to the sample surface SP, and as shown in FIGS. 3 and 4, the detection center which is the intersection of the sample surface SP and the detection optical axis DA. Is placed directly above the detector 6. Further, the detector 6 is arranged so that the area directly below the irradiation center is the outer peripheral portion of the detection surface 61. Specifically, as shown in each figure, the irradiation center, which is the intersection of the irradiation optical axis LA of the second X-ray generated by the secondary target 3 and the sample surface SP, and the detection center are a predetermined distance on the sample surface SP. It is configured to shift. In the present embodiment, the irradiation center is separated from the detection center by a predetermined distance with respect to the X-axis direction according to the tilting direction of the target surface 31 of the secondary target 3, and the separation distance is, for example, 3 mm or more and 10 mm. It is set as follows. In particular, as shown in FIG. 3, since the irradiation optical axis LA of the second X-ray and the detection optical axis DA of the detector 6 are arranged so as to be offset, the detection is detected by the detector 6 for the following reasons. The ratio of fluorescent X-rays to X-rays can be increased. In this example, the scattered X-rays generated at the irradiation center are dependent on the scattering angle, and a high-intensity component is generated centering on the direction perpendicular to the sample surface SP (Y-axis direction). In the present embodiment, the detection center is separated from the irradiation center, and the area directly below the irradiation center is located on the outer edge of the detection surface 61. Therefore, the intensity of the scattered X-rays in the solid angle of the field of view of the detector 6 It is possible to prevent the high directional component from being included so that the component with a weak scattering angle and a shallow scattering angle is mainly detected. On the other hand, fluorescent X-rays are not angle-dependent and are emitted uniformly in all directions. Therefore, even if the irradiation center and the detection center are deviated, the fluorescent X-rays incident on the solid angle of the field of view of the detector 6 The amount does not decrease as much as the scattered X-rays mentioned above. As a result, the background value due to the influence of scattered X-rays on the sample surface SP of the second X-ray can be reduced in the output of the detector 6, and the lower limit of detection of fluorescent X-rays mainly of silicon (Si) can be lowered. ..

The function of the concentration calculator 7 is realized by, for example, a CPU, a memory, an A / D converter, a D / A converter, and a so-called computer having various input / output means. In this concentration calculator 7, the program stored in the memory is executed by the CPU, and various devices cooperate to determine the concentration of silicon (Si) contained in the liquid sample LS based on the output of the detector 6. calculate. As a specific calculation formula, for example, a known one is used.

According to the fluorescent X-ray analyzer 100 of the present embodiment configured in this way, silicon, which is a trace element contained in the liquid sample LS in the liquid state without cooling or evaporating the liquid sample LS. The (Si) concentration can be measured based on fluorescent X-rays.

That is, in the present embodiment, since the irradiation center of the second X-ray on the sample surface SP and the detection center of the detector 6 are separated from each other, the directional component having high intensity among the scattered X-rays generated on the sample surface SP Is difficult to detect by the detection surface 61, and the ratio of fluorescent X-rays of silicon (Si) to the X-rays detected by the detector 6 can be increased. As a result, the lower limit of detection of silicon (Si) can be lowered as compared with the conventional case.

Further, since at least the target surface 31 of the secondary target 3 is formed of phosphorus (P), the energy of the second X-ray generated by the secondary target 3 is a large amount of phosphorus (P) fluorescence contained in the liquid sample LS. By reducing the generation of X-rays, only fluorescent X-rays of silicon (Si) contained in a small amount in the liquid sample LS can be generated. Therefore, the peak of the fluorescent X-ray of silicon (Si) is not hidden in the hem portion of the peak of the fluorescent X-ray of phosphorus (P) which is present in a large amount. Therefore, the concentration of silicon (Si) can be accurately measured from fluorescent X-rays having low intensity of light elements such as silicon (Si). In other words, a liquid that contains elements with consecutive atomic numbers, such as silicon (Si) and phosphorus (P), and has a large amount of second elements that interfere with the first element to be measured. Since it is a sample, it is considered difficult to separate and analyze each of them by fluorescent X-ray analysis in the past, and the concentration of trace elements that has not even been attempted to be measured industrially is the concentration of the present embodiment. This is possible with the fluorescent X-ray analyzer 100.

Furthermore, the secondary target 3, the liquid sample LS, and the detector 6 are densely arranged. The optical path length of each X-ray is shortened to prevent attenuation. Further, since the X-ray transmission film 5 is also set to have a thin film thickness, it is possible to reduce the attenuation when X-rays pass through the X-ray transmission film 5. Therefore, fluorescent X-rays can be detected with the intensity required to measure the concentration of silicon (Si) contained in the liquid sample LS, which is a trace amount of a light element.

Other embodiments will be described.

The fluorescent X-ray analyzer according to the present invention is not limited to measuring the concentration of silicon (Si) contained in the phosphoric acid solution. It can be used to measure the concentration of the first element based on fluorescent X-rays with respect to a liquid sample containing the first element to be measured and the second element having an atomic number larger than that of the first element. The difference between the atomic numbers of the first element and the second element was 1, but the difference between the atomic numbers of the first element and the second element may be 2, and the difference between the atomic numbers is larger than 2. Is also good.

In the above embodiment, a part of the liquid sample is sampled and the fluorescent X-ray analysis is performed as it is without cooling or evaporating. For example, the fluorescent X-ray analysis is performed while the liquid sample is flowing. , Real-time in-line density measurement may be realized. For example, a branch flow path formed of an X-ray permeable film is formed in a part of a pipe through which a liquid sample flows, and fluorescent X-ray analysis is performed in that part, or a window made of an X-ray permeable film is formed in a part of the pipe. May be formed and fluorescent X-ray analysis may be performed through the window.

The arrangement and orientation of each device constituting the fluorescent X-ray analyzer is not limited to the one shown in the above embodiment. For example, the detection optical axis of the detector may be configured to be obliquely incident on the sample surface instead of being vertically incident on the sample surface. In this case, in the arrangement shown in FIGS. 1 to 4, the detection surface of the detector may be tilted toward the X-ray source side where the first X-ray is emitted. In this way, the irradiation center and the detection center can be further shifted to make it difficult for the detector to detect the scattered X-rays generated on the detection surface of the liquid sample, and the proportion of the detected fluorescent X-rays can be increased. The direction in which the detector is tilted may be appropriately different depending on the type of the liquid sample and the equipment used. For example, the detector may be tilted so that the detection surface faces the side opposite to the X-ray source. Further, the target surface of the secondary target is not limited to the one that is inclined with respect to both the XZ plane and the YZ plane as in the above embodiment, but only with respect to either the XZ plane or the YZ plane. It may be inclined.

Further, as shown in FIG. 6, the secondary target 3 may be composed of a plurality of target elements 3E, and the second X-ray generated by each target element 3E may be separately irradiated to the sample surface SP. More specifically, the target element 3E may be arranged in a substantially V shape so as to sandwich the detector 6 in a mirror plane symmetry with respect to the detection optical axis DA. In this way, the fluorescent X-rays generated by the first element from the sample surface SP are incident on the detector 6 symmetrically with respect to the detection optical axis DA. Can be doubled. As a result, the measurement time can be shortened by about half, or the statistical measurement error can be reduced and more accurate measurement results can be obtained in the same measurement time.

The element constituting the secondary target is not limited to phosphorus (P), but may be zirconium (Zr) as shown in FIG. If it is Lα ray which is a component of fluorescent X-ray of zirconium, the above-mentioned relationship between energies is satisfied and the same effect can be obtained. Further, the secondary target may be one formed of yttrium (Y). Further, any element can be used as the secondary target as long as it is an element that generates a second X-ray satisfying E1 <EP <E2.

Various embodiments of the present invention can be considered depending on the relationship between the atomic numbers and the concentration of the first element and the second element to be measured. For example, a fluorescent X-ray analyzer may be used in which the elements constituting the secondary target are selected so as to satisfy E1 <EP <E2 in a state where the irradiation center and the detection center are aligned on the sample surface without shifting. Alternatively, fluorescent X-rays of both the first element and the second element may be generated with the irradiation center and the detection center shifted by a predetermined distance.

Further, the material constituting the secondary target described in the embodiment may be used as a material for generating primary X-rays, and the sample may be directly irradiated with primary X-rays.

Other than that, various modifications may be made to each embodiment or a part of each embodiment may be combined as long as it does not contradict the gist of the present invention.

According to the present invention, it is possible to provide a fluorescent X-ray analyzer capable of sufficiently detecting fluorescent X-rays of a light element such as silicon (Si) and performing quantitative analysis.

Claims

A fluorescent X-ray analyzer that analyzes a liquid sample containing a first element to be measured and a second element having an atomic number larger than that of the first element.
An X-ray source that emits the first X-ray and
A secondary target, which is excited by the first X-ray to generate a second X-ray and is provided so that the second X-ray is incident on the liquid sample,
A detector that detects fluorescent X-rays generated in the liquid sample excited by the second X-rays, and
A concentration calculator for calculating the concentration of the first element in the liquid sample based on the output of the detector is provided.
The irradiation center, which is the intersection of the second X-ray irradiation optical axis with respect to the sample surface of the liquid sample, and the visual field center, which is the intersection of the detection optical axis of the detector with respect to the sample surface, are separated from each other in the sample surface. A fluorescent X-ray analyzer characterized in that it is configured as such.
An X-ray permeable membrane that comes into contact with the liquid sample and forms a sample surface is further provided.
The fluorescent X-ray analyzer according to claim 1, wherein the second X-ray is configured to pass through the X-ray transmission membrane and irradiate the liquid sample.
The fluorescent X-ray analyzer according to claim 2, wherein the X-ray transmission film is made of polyimide, aromatic polyetherketone, polyphenylene sulfide, aramid, graphene, or diamond-like carbon.
The first X-ray irradiation light axis is the Z-axis, the Z-axis is orthogonal to the light source point of the X-ray source, the axis forming the XZ plane parallel to the sample surface is the X-axis, and the light source point of the X-ray source is the X-axis. As you can see, when the axis orthogonal to the X-axis and Z-axis is the Y-axis,
The secondary target comprises a target surface on which the first X-ray is incident.
The fluorescent X-ray analyzer according to any one of claims 1 to 3, wherein the target surface is inclined with respect to the XZ plane and also with respect to the YZ plane.
The target plane is tilted with respect to the XZ plane and the YZ plane so that the normal vector with respect to the target plane is (X, Y, Z) = (-1 / 2,1 / √2, -1 / 2). The fluorescent X-ray analyzer according to claim 4.
The detector comprises a detection surface for detecting fluorescent X-rays.
The fluorescent X-ray analyzer according to claim 4 or 5, wherein the detection surface is inclined with respect to the XZ plane and the detection surface faces the X-ray source side.
The fluorescent X-ray analyzer according to any one of claims 1 to 5, wherein the secondary target comprises a plurality of target elements arranged so as to separately generate a second X-ray.
The fluorescent X-ray analyzer according to claim 7, wherein the two target elements are arranged so as to sandwich the detector.
The first element is silicon (Si).
The fluorescent X-ray analyzer according to any one of claims 1 to 8, wherein the second element is phosphorus (P).
The fluorescent X-ray analyzer according to claim 9, wherein the distance between the irradiation center and the visual field center is 3 mm or more and 10 mm or less.