JP2010190679A - X-ray analysis apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray analysis apparatus capable of condensing X rays without lowering the intensity when irradiating a minute area with the X rays. <P>SOLUTION: The apparatus includes: an X-ray source 1; a first X-ray converting plate 2 for converting the X-rays emitted by the X ray source 1 into a parallel-ray bundle; a second X-ray converting plate 3 for condensing the bundled parallel-ray having passed through the first X-ray converting plate 2 on to a sample position; and a detector 4 for detecting secondary X rays emitted by a sample which is placed on the sample position and irradiated with the condensed X rays. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an X-ray analysis method for collecting X-rays from an X-ray source, irradiating a sample, and analyzing generated secondary X-rays, and an X-ray analyzer using the same.

In recent years, X-ray analyzers have been used in a wide range of fields from biological analysis to manufacturing processes for electronic components such as semiconductors. In each of these fields, it is required to perform an analysis on a minute region. In such an analysis on a minute region, it is necessary to irradiate a measurement target with X-rays having a minute diameter. . As a method for condensing X-rays in such an analyzer, a method using an optical element such as a collimator or an X-ray mirror is known (for example, see Patent Document 1).

JP-A-10-339798

By the way, in the above-described prior art, when the X-ray is focused on a very small diameter, there arises a problem that the X-ray intensity is lowered. In addition, there is a problem that an X-ray source and its peripheral devices become large in order to maintain a sufficient X-ray intensity even when the intensity is reduced due to light collection. In addition, when an optical element is used without using such a large-scale apparatus, X-rays cannot be sufficiently condensed due to the processing accuracy of the optical element.
The present invention has been made in view of the above circumstances, and provides a relatively compact X-ray analyzer that can irradiate a small-diameter X-ray beam without reducing the X-ray intensity. Objective.

The present invention made to achieve the above object has the following features.
An X-ray analyzer according to the present invention passes through an X-ray source, a first X-ray conversion plate that converts X-rays radiated from the X-ray source into parallel beam bundles, and the first X-ray conversion plate A second X-ray conversion plate for condensing the parallel beam bundle at the sample position, and a detector for detecting secondary X-rays generated from the sample irradiated with the condensed X-ray placed at the sample position It is characterized by being configured.
With such a feature, the X-ray analyzer according to the present invention can collect and irradiate the sample without reducing the intensity of the X-ray without using a large-scale apparatus.

  In the X-ray analyzer according to the present invention, the second X-ray conversion plate is preferably movable in the optical axis direction. Thereby, the focal position can be moved in the optical axis direction.

  In addition, the X-ray analyzer is preferably composed of a control device that controls the position of the second X-ray conversion plate so that the detection state of secondary X-rays by the detector is optimized. . Thereby, even when measuring samples having different thicknesses, the position of the second X-ray conversion plate can be controlled so that the focal position becomes the optimum position.

  In the X-ray analysis apparatus according to the present invention, the first X-ray conversion plate and the second X-ray conversion plate have a plurality of through holes penetrating from the front surface to the back surface, and the side surfaces of the through holes. Preferably totally reflects the incident X-rays. Thereby, the optical path of the X-ray can be converted without impairing the intensity of the X-ray.

The X-ray analyzer according to the present invention preferably includes a collimator between the second X-ray conversion plate and the sample position. Thereby, it can prevent that X-rays are irradiated other than the target location of a sample.
Moreover, in the X-ray analyzer which concerns on this invention, it is preferable that the cross-sectional shape of the through-hole of both said 1st X-ray conversion plate and said 2nd X-ray conversion plate is circular. Thereby, X-rays can be condensed into a substantially circular shape.
Moreover, in the X-ray analyzer which concerns on this invention, it is preferable that the cross-sectional shape of the through-hole of any one or both of a 1st X-ray conversion plate and said 2nd X-ray conversion plate is a square. Thereby, both of the two multiplates can prevent the X-ray intensity from being lowered as compared with the case where the cross-sectional shape of the through hole is circular.

In the X-ray analyzer according to the present invention, it is preferable that the detector detects fluorescent X-rays.
In the X-ray analysis method according to the present invention, the X-ray emitted from the X-ray source is converted into a parallel beam by the first X-ray conversion plate, and the parallel beam passing through the first X-ray conversion plate is converted. The second X-ray conversion plate collects light at a sample position, and detects secondary X-rays generated from the sample irradiated with the condensed X-ray placed at the sample position.

According to the X-ray analysis apparatus of the present invention, it is possible to collect light without reducing the intensity of X-rays and irradiate the sample with X-rays without using a large-scale apparatus.

It is a typical side view of a structure of a X-ray analyzer. It is a schematic diagram which shows the optical path by a multichannel plate. It is a schematic front view of a multichannel plate having a circular opening. It is a model front view of the multichannel plate with a square opening. It is a schematic diagram which shows the focus movement by the movement of the multichannel plate by the side of a sample. It is a schematic diagram of the condensing by the multichannel plate which has a square opening.

EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated with reference to an accompanying drawing. FIG. 1 is a side view schematically showing the configuration of the X-ray analyzer. The X-ray analyzer includes an X-ray source 1, a first multi-channel plate 2, a second multi-channel plate (second X-ray conversion plate) 3, a collimator 6, and a stage 8 on which a sample 7 is placed. And a holding unit and an X-ray detector 5.
The X-ray source 1 is a device that generates X-rays for irradiating a measurement object. Radial X-rays are irradiated to the first multi-channel plate (first X-ray conversion plate) 2 from the opening of the X-ray source 1.
The first multi-channel plate (first X-ray conversion plate) 2 is a plate that receives radial X-rays from the X-ray source 1 and converts them into parallel light. The first multi-channel plate 2 is installed on the optical axis between the X-ray source 1 and the sample stage 8.
The second multi-channel plate (second X-ray conversion plate) 3 is a plate that condenses the parallel light that has passed through the first multi-channel plate 1 on the sample 7, and is fixed by the holding unit 10. The holding unit 10 can move up and down in the optical axis direction when the driving unit 9 operates, and accordingly, the second multi-channel plate 3 also moves up and down in the optical axis direction. When the second multi-channel plate 3 moves up and down in the optical axis direction, the focal position of the light emitted from the second multi-channel plate 3 also moves. The drive unit 9 moves the second multi-channel plate 3 through the holding unit 10 under the control of the control unit 4. For example, when the sample 7 is thick, the control unit 4 can move the position of the second multi-channel plate so that the focal position is optimized according to the sample.
The X-rays that have passed through the second multi-channel plate 3 are collected and irradiated on the sample 7 on the sample stage 8. Here, the focal point of the X-ray is preferably on the sample 7. Also, the collimator 6 can be installed on the optical axis between the second multi-channel plate 3 and the sample stage 8. The collimator 6 can remove the diffracted light slightly spreading near the focal point when being collected by the second multi-channel plate 3.
The X-rays that have passed through the second multi-channel plate 3 are irradiated onto the sample 7, and secondary X-rays are generated from the sample 7. The detector 5 detects the secondary X-ray and transmits a signal to the control unit 4. Here, the detector 5 detects, for example, fluorescent X-rays as secondary X-rays.

  FIG. 2 is a schematic diagram showing an optical path by a multichannel plate. FIG. 3 is a schematic front view of a multi-channel plate having a circular opening. FIG. 4 is a schematic front view of a multi-channel plate having a square opening.

  As shown in FIG. 3, the multi-channel plate has a substantially disk shape, and has a plurality of through holes on the surface thereof. In the embodiment of FIG. 3, a plurality of through holes 21 having a circular cross section are provided. The through hole 21 has a diameter of 10 μm to 100 μm. Further, the surface of the through hole has a property of totally reflecting X-rays irradiated at an acute angle. By this total reflection, the multichannel plate can change the optical path of the X-rays that have passed through the through hole 21.

  The first multi-channel plate 2 in FIG. 2 is a side view of the AA cross section in FIG. The first multi-channel plate 2 has a shape curved in a spherical shape. Due to the warp due to this curvature, the circular through hole 21 faces in the optical axis direction. In FIG. 2, the warped concave surface of the first multi-channel plate 2 faces the direction of the X-ray source 1.

The X-ray 11 irradiated from the X-ray source 1 is totally reflected by the side surface of the through hole of the first multi-channel plate 2 and converted into parallel line side X-rays parallel to the optical axis 12. At this time, the relationship between the distance f from the center of the first multichannel plate 2 to the focal point and the radius of curvature R of the multichannel plate is f = R / 2.
The cross-sectional shape of the through-hole 21 provided in the first multichannel plate 2 is circular or square as shown in FIGS. When the diameter when the cross-sectional shape is circular or the length of one side when the cross-sectional shape is square is D, this D is 10 μm to 100 μm. The thickness L and the curvature radius R of D and the multichannel plate are set so that the incident angle of X-rays is smaller than the critical angle so that the X-rays can be totally reflected by the wall surface of the hole. This critical angle is approximately 2 ° when the X-ray energy is 1 keV. When the thickness L of the first multi-channel plate 2 is increased, the energy of X-rays is reduced due to multiple reflection, so the ratio L / D of D and L is about 100.
The through hole 21 is formed by removing a glass material serving as a core by etching or the like, and the surface roughness of the wall surface of the through hole 21 is several nm.
FIG. 4 shows a front view of a multi-channel plate in which the through hole 21 has a square cross section. A multi-channel plate having a square cross-sectional shape of the through hole has higher light collection efficiency than a multi-channel plate having a through-hole having a circular cross-sectional shape. However, when the second multi-channel plate 3 having a rectangular through hole 21 has a rectangular cross-sectional shape, spreading due to diffracted X-rays occurs near the focal point.

  FIG. 6 is a schematic view of light collection by a multi-channel plate having a square opening. The condensing shape 13 is a condensing shape of X-rays collected by the first multi-channel plate 2 and the second multi-channel plate 3. The diffraction pattern 14 is a diffraction pattern when a through-hole 21 having a square cross section is used in the second multichannel plate 3. The diffraction pattern when the through hole 21 having a square cross section is used in the second multi-channel plate is a cross pattern as shown in FIG.

In FIG. 6, a collimator 6 is provided immediately before the focal position so as not to irradiate the sample 7 with the noise of the cross pattern. By collimating the spread X-ray, the high-intensity X-ray can be irradiated only to the focal position. Further, by making only the multichannel plate 3 a circular hole, it is also possible to reduce the spread of light collection at the focal position. However, even in a multi-channel plate having a circular cross-sectional shape of the through-hole, it is not possible to collect a complete point image. Even in this case, it is effective to arrange the collimator 6.
FIG. 5 is a schematic diagram showing focal point movement by movement of the multi-channel plate on the sample side. The figure on the left shows the position of the second multichannel plate 3 when the sample 7 is thin. In this case, the second multi-channel plate 3 is positioned near the sample stage 8, and the focal position is lowered so as to hit the sample surface. The right figure shows the case where the sample 7 is thick. The second multi-channel plate is positioned far from the sample 7, and the focal position is upward so that the focal point comes to the surface of the material.
Thus, the position of the second multi-channel plate 3 in the optical axis direction can be variably arranged. The position of the second multi-channel plate 3 can be moved by the control unit 4 controlling the drive unit 9. The control unit 4 can control the drive unit 9 so as to optimize the focal position in consideration of, for example, a difference in thickness of the sample 7.

DESCRIPTION OF SYMBOLS 1 X-ray source 2 1st multichannel plate 3 2nd multichannel plate 4 Control part 5 Detector 6 Collimator 7 Sample 8 Sample stage 9 Drive part 10 Holding part 11 X-ray 12 Optical axis 14 Diffraction pattern 21 Through-hole

Claims (9)

An X-ray source, and a first X-ray conversion plate for converting X-rays emitted from the X-ray source into parallel beam bundles;
A second X-ray conversion plate for condensing the parallel beam bundle that has passed through the first X-ray conversion plate at a sample position;
A detector for detecting secondary X-rays generated from the sample irradiated with the condensed X-rays placed at the sample position;
X-ray analyzer composed of The X-ray analyzer according to claim 1, wherein the second X-ray conversion plate is movable in the optical axis direction. 3. The X-ray analyzer according to claim 1, further comprising a control device that controls the position of the second X-ray conversion plate so that the detection state of secondary X-rays by the detector is optimized. The first X-ray conversion plate and the second X-ray conversion plate have a plurality of through holes penetrating from the front surface to the back surface, and side surfaces of the through holes totally reflect incident X-rays. The X-ray analyzer according to any one of claims 1 to 3, characterized in that: The X-ray analyzer according to claim 1, further comprising a collimator between the second X-ray conversion plate and the sample position. 6. The X-ray according to claim 1, wherein the through hole of either or both of the first X-ray conversion plate and the second X-ray conversion plate is circular. Analysis equipment. 6. The X-ray according to claim 1, wherein the through hole of either or both of the first X-ray conversion plate and the second X-ray conversion plate has a square shape. Analysis equipment. The X-ray analyzer according to claim 1, wherein the detector detects fluorescent X-rays. X-rays emitted from the X-ray source are converted into parallel beam bundles by the first X-ray conversion plate,
The parallel line bundle that has passed through the first X-ray conversion plate is condensed at the sample position by the second X-ray conversion plate,
An X-ray analysis method for detecting secondary X-rays generated from a sample irradiated with the condensed X-rays placed at the sample position.

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