JP2006194632A - Total reflection x-ray fluorescence analyzer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a total reflection X-ray fluorescence analyzer having a simple constitution, wherein the intensity of a fluorescence X-ray is hardly influenced by change of a load of an X-ray tube. <P>SOLUTION: This analyzer is equipped with the X-ray tube 1 of a point light source having in a cylindrical casing 11 a bar-like target 10 wherein the axial direction of the casing 11 is its longitudinal direction L, and a filament 13 arranged in the longitudinal direction L of the target, wherein thermal electrons 14 radiated from the filament 13 which is a cathode are allowed to collide with the end face of the target 10 which is an anode, and an X-ray generated from the target 10 and directed to the side wall of the casing 11 is emitted through a window 12. In the analyzer, the X-ray 2 from the X-ray tube 1 is monochromatized by a spectral element 4, and allowed to enter the sample surface 5a at a fine incident angle α as a belt-like primary X-ray 3, and the intensity of a generated fluorescence X-ray 6 is measured by a detection means 7. In this case, the X-ray tube 1 is arranged so that the longitudinal direction L of the target is parallel to the sample surface 5a. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a total reflection fluorescent X-ray analyzer.

  Conventionally, as described in Patent Document 1 and Patent Document 2, for example, X-rays from an X-ray tube are monochromatized by a spectroscopic element and incident as a primary X-ray at a small incident angle on a sample surface. There is a total reflection fluorescent X-ray analyzer that measures the intensity of fluorescent X-rays with a detection means. Here, with regard to the X-ray tube, a cylindrical X-ray tube is arranged upright so as to be substantially orthogonal to the sample surface. Such a configuration is made so that the X-ray tube is irradiated with primary X-rays having the highest possible intensity with the line light source and the sample surface in parallel, and the X-ray tube is arranged in the analyzer. It depends on ease.

When the load of the X-ray tube is changed in this configuration, a rod-shaped target (see Patent Documents 3 and 4) whose longitudinal direction is the axial direction of the casing expands and contracts in the cylindrical casing of the X-ray tube. The height of the focal point, that is, the X-ray generation point with respect to the sample surface changes. As a result, the incident angle of the primary X-rays on the sample surface also changes. However, even if the change is slight, it occurs in the total reflection X-ray fluorescence analysis where the incident angle is very small and near the critical angle of total reflection. This greatly affects the intensity of fluorescent X-rays. Therefore, the optical system is stabilized by suppressing the expansion and contraction of the target due to thermal expansion by maintaining the temperature constant by cooling the X-ray tube with water.
JP 2002-357572 A JP-A-8-136479 JP 2002-350373 A (FIG. 1) JP 59-221948 (FIG. 1)

  However, the configuration of the apparatus is complicated by piping for cooling the X-ray tube with water, and the installation location of the apparatus is limited because a cooling water supply source is required.

  The present invention has been made in view of the above-described conventional problems, and provides a total reflection X-ray fluorescence analyzer having a simple configuration and hardly affecting the intensity of fluorescent X-rays even when the load of the X-ray tube changes. Objective.

  In order to achieve the above object, a total reflection X-ray fluorescence spectrometer of the present invention first includes a rod-shaped target having a longitudinal direction in the axial direction of the casing, and a longitudinal direction of the target in a cylindrical casing. The thermal electrons emitted from the filament as a cathode collide with the end face of the target as an anode, and X-rays generated from the target and directed toward the side wall of the housing are opened in a window. An X-ray tube of a point light source that emits through the light source is provided. Then, the X-ray from the X-ray tube is monochromatized by a spectroscopic element and is incident on the sample surface as a band-shaped primary X-ray at a minute incident angle, and the intensity of the generated fluorescent X-ray is measured by a detecting means. Furthermore, the X-ray tube is arranged so that the longitudinal direction of the target is parallel to the sample surface.

  According to the present invention, the X-ray tube is arranged so that the longitudinal direction of the target is parallel to the sample surface. Therefore, even if the load of the X-ray tube changes and the target expands and contracts, The primary X-rays only move in the width direction, and the incident angle does not change. Therefore, it hardly affects the intensity of the fluorescent X-ray, and does not require water cooling of the X-ray tube, and the configuration of the apparatus is simplified.

  In the present invention, a plurality of the X-ray tubes may be provided, and a moving mechanism for moving the X-ray tubes may be provided, with the direction orthogonal to the longitudinal direction of the targets of the X-ray tubes as the moving direction. However, a selection function for arranging one X-ray tube selected from the plurality of X-ray tubes so that X-rays from the X-ray tube enter the spectroscopic element, and an X-ray arranged by the selection function It is preferable to have a fine adjustment function for finely adjusting the position of the tube in the moving direction.

  In the total reflection X-ray fluorescence analyzer, in order to change the wavelength of the primary X-ray, there may be a case where a plurality of X-ray tubes with different target materials are selected. In order to finely adjust the direction of moving the selected X-ray tube to be placed in the X-ray optical path and the height with respect to the sample surface after placement in order to place the X-ray tube upright and parallel to each other. The direction of movement is orthogonal. Therefore, a separate moving mechanism is required for each movement, and the configuration of the apparatus is complicated. On the other hand, according to the preferable configuration of the present invention, the direction in which the selected X-ray tube is moved in order to arrange it in the X-ray optical path, and the direction in which the selected X-ray tube is moved in order to finely adjust the height with respect to the sample surface. Are both in the direction perpendicular to the longitudinal direction of the target and are the same, a single moving mechanism is sufficient for both movements, and the configuration of the apparatus is simplified.

  Hereinafter, a total reflection X-ray fluorescence spectrometer according to an embodiment of the present invention will be described with reference to the drawings. As shown in the plan view of FIG. 2, this apparatus first has a rod-like target 10A having a longitudinal direction L in the axial direction of the casing 11 and a longitudinal direction of the target 10A. The thermoelectron 14 emitted from the filament 13 serving as the cathode collides with the end face of the target 10A serving as the anode, and is generated from the target 10A and travels toward the side wall of the housing 11. A point light source X-ray tube 1A for emitting X-rays 2A through a window 12 and a diaphragm 15 having a dot-like hole is provided. The target 10A is composed of a target support 10Ab and a target material 10Aa that is attached to the end of the filament 13 and collides with the thermoelectrons 14, and the longitudinal direction L of the target 10A is parallel to the sample surface 5a. An X-ray tube 1A is arranged.

  Then, as shown in FIG. 1, which is a front view, the X-ray 2A from the X-ray tube 1A is monochromatized by the spectroscopic element 4 and is incident on the sample surface 5a as a strip-shaped primary X-ray 3A at a small incident angle α. The intensity of the generated fluorescent X-ray 6 is measured by a detection means 7 such as an SSD. The X-ray 2A from the X-ray tube 1A as a point light source travels while spreading in a conical shape, but is formed between the lower surface (incident surface) of the spectroscopic element 4 and the upper end of the knife edge 16 provided immediately below it. By passing through a linear slit (extending in the direction perpendicular to the paper surface) and being diffracted by the spectroscopic element 4, it is monochromatic and becomes a strip-like primary X-ray (having a width in the direction perpendicular to the paper surface) 3A. The sample 5 is a silicon wafer, for example, and is placed on the sample table 9.

  Furthermore, in the apparatus of this embodiment, in order to change the wavelength of the primary X-ray 3, two X-ray tubes 1A and 1B having different target materials are selected. That is, it has the same structure as the X-ray tube 1A described above, but includes another X-ray tube 1B having a target material 10Ba (FIG. 2) made of a different material from the target material 10Aa of the X-ray tube 1A. Yes. And the moving mechanism 8 which moves X-ray tube 1A, 1B by making the direction orthogonal to the longitudinal direction L (FIG. 2) of the targets 10A, 10B of those X-ray tubes 1A, 1B into the moving direction M is provided.

  The moving means 8 lays down the X-ray tube 1A so that the longitudinal direction L (FIG. 2) of the targets 10A and 10B, that is, the axial direction of the casings 11 and 11 of the X-ray tubes 1A and 1B is parallel to the sample surface 5a. , 1B are mounted in a line up and down, and a pulse motor 8a for moving the mounting plate 8c in the moving direction M and a ball screw mechanism (or a rack and pinion mechanism or the like) 8b. The moving mechanism 8 has the following selection function and fine adjustment function, and each function is exhibited by being controlled by a control unit 17 such as a computer.

  When performing the selection function, for example, the X-ray tube 1A selected by the operator or the like from the two X-ray tubes 1A and 1B, the X-ray 2A from the X-ray tube 1A enters the spectroscopic element 4. Arrange as follows. FIG. 1 shows such a state, but when the X-ray tube 1B is selected in the state of FIG. 1, the attachment plate 8c is largely moved upward along the moving direction M to remove the X-ray tube 1B from the X-ray tube 1B. The X-ray 2B is arranged so as to enter the spectroscopic element 4. When performing the fine adjustment function, the mounting plate 8c is moved little by little along the movement direction M, and fine adjustment of the position in the movement direction M of the X-ray tube 1A, for example, arranged by the selection function, that is, the sample surface 5a. Make fine adjustments to the height. Note that three or more X-ray tubes may be provided in the same arrangement as described above. Further, when the X-ray tubes 1A and 1B are selected and finely adjusted, the spectroscopic element 4 is exchanged and the tilt angle is adjusted as necessary by the control unit 17, an exchange mechanism (not shown), a rotation mechanism, and the like.

  According to the apparatus of this embodiment, as shown in FIG. 2, the X-ray tubes 1A and 1B are arranged so that the longitudinal direction L of the targets 10A and 10B is parallel to the sample surface 5a. For example, even if the load of the X-ray tube 1A used changes and the target 10A expands and contracts, the band-shaped primary X-ray 3A only moves in the width direction with respect to the sample surface 5a, and the incidence shown in FIG. The angle α does not change. Therefore, the intensity of the fluorescent X-ray 6 is hardly affected, the water cooling of the X-ray tubes 1A and 1B is unnecessary, and the configuration of the apparatus is simplified.

  Further, in the apparatus of the present embodiment, in order to change the wavelength of the primary X-ray 3, two X-ray tubes 1A and 1B having different target materials are selected and selected. The direction of movement for placement in the linear light paths 2 and 3 and the direction of movement for fine adjustment of the height relative to the sample surface 5a after placement are both orthogonal to the longitudinal direction L (FIG. 2) of the target. Unlike the conventional case where a plurality of X-ray tubes are arranged so as to be substantially perpendicular to the sample surface and are arranged in parallel as in the prior art, if there is a single moving mechanism 8 for both movements, The configuration of the device is simple.

  When the X-ray tube is a linear light source, the linear light source, the linear portion on the incident surface of the spectroscopic element where the X-ray should be incident, and the sample surface are all parallel. Adjustments must be made strictly, but this requires skill. On the other hand, in the apparatus of this embodiment, since the X-ray tubes 1A and 1B are point light sources, tilt adjustment is performed on the X-ray tubes 1A and 1B, that is, tilt adjustment with the horizontal direction in FIG. There is no need to perform strictly, and only the relationship between the sample surface 5a and the spectroscopic element 4 needs to be adjusted strictly. In addition, when the X-ray tubes 1A and 1B are point light sources, the intensity of the primary X-rays 3A and 3B is lower than that of the case of the line light source. Since the water cooling of 1B is not required, the configuration of the apparatus is simplified, and the degree of freedom of the installation location is increased, so that the utility value of the apparatus of the present embodiment is great.

It is a front view which shows the total reflection X-ray fluorescence spectrometer of one Embodiment of this invention. It is a top view of the apparatus.

Explanation of symbols

1A, 1B X-ray tube 2A, 2B X-ray 3A, 3B from X-ray tube Primary X-ray 4 Spectroscopic element 5a Sample surface 6 Fluorescent X-ray 7 Detection means 8 Moving mechanism 10A, 10B Target 11 Housing 12 Window 13 Filament 14 Thermoelectron L Longitudinal direction M of target X Movement direction of X-ray tube α Incident angle of primary X-ray

Claims (2)

A cylindrical housing has a rod-shaped target whose longitudinal direction is the axial direction of the housing and a filament disposed in the longitudinal direction of the target, and thermionic electrons emitted from the filament as a cathode are anodes. An X-ray tube of a point light source that collides with the end face of the target and emits X-rays generated from the target toward the side wall of the housing through a window;
The X-ray from the X-ray tube is monochromatized by a spectroscopic element and is incident on the sample surface as a band-shaped primary X-ray at a minute incident angle, and the total reflection fluorescence X is measured by the detection means. A line analyzer,
A total reflection fluorescent X-ray analyzer in which the X-ray tube is arranged so that a longitudinal direction of the target is parallel to a sample surface. In claim 1,
A plurality of the X-ray tubes;
A moving mechanism for moving the X-ray tube with a direction perpendicular to the longitudinal direction of the target of the X-ray tube as a moving direction;
The moving mechanism is arranged by a selection function for arranging one X-ray tube selected from the plurality of X-ray tubes so that X-rays from the X-ray tube enter the spectroscopic element, and the selection function. A total reflection fluorescent X-ray analyzer having a fine adjustment function for finely adjusting the position of the X-ray tube in the moving direction.

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