JPH1144662A - Minute part x-ray analysis device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform X-ray diffraction measurement and X-ray fluorescence analytical measurement for a minute part of a sample at the same time while a positional relationship between the minute part of the sample and X-ray beam is kept appropriately, by devising allocation of two X-ray detectors and structure of a sample holder. SOLUTION: A minute part 22 of a sample 20 is irradiated with X-ray beam 36 through a collimator 12 at incident angle of 20-30 deg.. During measurement, the sample 20 is rotated around ϕ axis 26 and ω axis 34 so that the crystal grain present in X-ray irradiation region is oriented in various bearings. The ϕrotation is continuous rotation covering angular range of 360 deg., while the ωrotation is swinging rotation covering 0-90 deg., Diffraction X-ray is detected with a deflected position-sensitive proportional counter tube 16, while X-ray fluorescence with a semiconductor detector 18. The two X-ray detectors may be standstill during measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micropart X-ray analyzer capable of simultaneously measuring a diffraction X-ray and a fluorescent X-ray on a micropart of a sample.

[0002]

2. Description of the Related Art An apparatus described in JP-A-54-685 and an apparatus disclosed in Japanese Patent Publication No. Sho 60-29896, which can simultaneously measure diffraction X-rays and fluorescent X-rays on minute portions of a sample, are disclosed. An apparatus described in Japanese Patent Application Laid-Open Publication No. H10-26095 is known. In the apparatus described in JP-A-54-685, one semiconductor detector is used as an X-ray detector, and this semiconductor detector measures both diffracted X-rays and fluorescent X-rays. In this apparatus, "continuous X-rays" (X-rays having a continuous wavelength) are used as X-rays incident on a sample. Diffracted X-rays and fluorescent light are obtained by performing energy analysis on the detected X-rays with a multi-peak analyzer. Both X-rays can be measured simultaneously.

On the other hand, in the apparatus described in Japanese Patent Publication No. 60-29896, two proportional counters are used as an X-ray detector.
Are used for measuring fluorescent X-rays. To measure diffracted X-rays, the first proportional counter is moved,
This movement realizes the X-ray diffraction measurement of the angle dispersion method. In order to measure fluorescent X-rays, a balanced filter that allows only fluorescent X-rays from a target element to pass is disposed in front of the detection surface of the second proportional counter.

Japanese Patent Application Laid-Open No. Hei 5-188019 describes an apparatus in which diffracted X-rays and fluorescent X-rays are separately measured by different types of X-ray detectors. However, it does not measure a minute part of the sample. In this apparatus, a curved position-sensitive detector is used to detect diffracted X-rays, and a semiconductor detector is used to detect fluorescent X-rays. Further, an X-ray detector for EXAFS measurement is also provided. The measurement of the diffracted X-ray, the measurement of the fluorescent X-ray, and the EXAFS measurement are separately performed. That is, the goniometer and the X-ray detector are optimally arranged according to the type of measurement. To enable such an arrangement, a curved position sensitive detector or semiconductor detector is made retractable so as not to interfere with the goniometer or other detectors. Another characteristic of the incident X-rays is that the incident X-rays are incident on the sample at a minute angle equal to or smaller than the critical angle for total reflection.

[0005]

The conventional apparatus described in Japanese Patent Application Laid-Open No. 54-685 uses continuous X-rays for measuring diffracted X-rays. The detection intensity of the diffracted X-ray becomes weak. When a plurality of diffraction peaks are detected and the peak intensity ratio is determined, since the X-ray energies of the respective diffraction peaks are different,
Intensity correction is required. By the way, in this publication,
Although it is said that it is possible to measure a minute part of 200 μm,
When the X-ray irradiation area of the sample becomes minute as described above, the number of crystal grains contributing to diffraction becomes very small while the posture of the sample remains stationary, and the detection intensity of the diffracted X-ray becomes very weak.

The conventional apparatus described in Japanese Patent Publication No. 29896/1985 uses a combination of a proportional counter and a balanced filter for measuring X-ray fluorescence, so that only specific elements can be analyzed by X-ray fluorescence. X-ray fluorescence analysis of arbitrary plural elements is impossible in principle. In that sense, the applications are limited. Also, since the proportional counter is moved to measure the diffracted X-rays, it takes time to measure the diffracted X-rays (weak intensity) from the minute portions. further,
The irradiation position of the sample (XY movement) can be changed, but the posture of the sample cannot be changed. Therefore, when measuring a minute part of the sample, the number of crystal grains contributing to diffraction becomes very small. , The detection intensity of the diffracted X-rays becomes very weak.

[0007] In the conventional apparatus described in Japanese Patent Application Laid-Open No. 5-188019, the incident X-ray is made to enter the sample at a small angle equal to or smaller than the critical angle for total reflection, so that the irradiation area on the sample is long in the irradiation direction. Therefore, it is impossible to measure only a specific minute portion. Further, neither diffraction X-rays nor fluorescent X-rays are measured at the same time.

After all, in the various conventional devices described above,
It has not been possible to perform X-ray diffraction measurement and X-ray fluorescence analysis measurement of a minute portion of a sample simultaneously and with high accuracy in a short time.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to simultaneously perform X-ray diffraction measurement and X-ray fluorescence analysis measurement of a minute portion of a sample in a short time. An object of the present invention is to provide a microscopic X-ray analyzer that can be performed with high accuracy.

[0010]

An X-ray microanalyzer according to the present invention is capable of simultaneously measuring a diffracted X-ray and a fluorescent X-ray from a microscopic portion of a sample by separate X-ray detectors. The sample holder for that purpose is also devised. That is, the micropart X-ray analyzer of the present invention has the following (a) to
(E). (A) An X-ray source that generates an X-ray beam including characteristic X-rays. (B) A collimator arranged between a sample and an X-ray source to irradiate an X-ray beam to a minute part (about 100 μm or less in diameter) of the sample. (C) A sample holder that can rotate the sample around two rotation axes while keeping the incident angle of the X-ray beam on the sample surface within a range of 20 to 30 degrees. (D) A position-sensitive first X-ray detector for detecting a diffracted X-ray diffracted by the minute portion of the sample. (E) A second energy dispersing method for detecting fluorescent X-rays generated in the minute portion of the sample
X-ray detector.

The first axis of rotation of the sample holder is on the same straight line as the X-ray beam incident on the sample, and the second axis of rotation of the sample holder is the same as the normal of the sample surface in the minute part. Being on a straight line, the second rotation axis rotates around the first rotation axis.

As the first X-ray detector, a curved position-sensitive proportional counter having the minute portion as the center of curvature can be used. Alternatively, an imaging plate may be used as the first X-ray detector. Further, a semiconductor detector can be used as the second X-ray detector.
Other than this, another X-ray detector may be used as the second X-ray detector as long as it is an energy dispersive method.

The apparatus of the present invention is used as follows. An X-ray beam is incident on a minute part of the sample at an incident angle of 20 to 30 degrees. By rotating the sample around two rotation axes during the measurement, the crystal grains existing in the X-ray irradiation region are directed in various directions. Thereby, even if the X-ray irradiation area is minute, a diffraction pattern without leakage can be obtained. The sample rotation about the second axis of rotation (Φ axis) is an in-plane rotation of the sample, which preferably rotates continuously over an angular range of 360 degrees. The sample rotation about the first rotation axis (ω axis) is preferably oscillatingly rotated in an angle range of 0 to 90 degrees. This makes it possible to always detect diffracted X-rays and fluorescent X-rays by using two X-ray detectors while rotating the sample around two rotation axes. Both X-ray detectors may remain stationary during the measurement. Therefore, compared to the method of measuring by moving the detector,
Measurement time is short. Originally, in the X-ray analysis measurement of a minute part, since the intensity of the diffracted X-ray and the fluorescent X-ray is weak, the measurement tends to take a long time. On the other hand, the apparatus of the present invention is advantageous because it can measure diffracted X-rays and fluorescent X-rays simultaneously, and can use the two detectors in a stationary state. Both simultaneous measurement and stationary measurement help to reduce the measurement time, and are convenient for measurement of minute parts.

By using the apparatus of the present invention, elemental analysis (measurement of X-ray fluorescence) and crystal analysis (measurement of X-ray diffraction) can be simultaneously performed on a minute portion of a sample.

[0015]

FIG. 1 is a perspective view showing an embodiment of the present invention, and FIG. 2 is a side view thereof. In FIG. 1, the micropart X-ray analyzer includes an X-ray source 10, a collimator 12, a sample holder 14, a curved position-sensitive proportional counter 16, and a semiconductor detector 18. The X-ray source 10 generates characteristic X-rays specific to the target. The collimator 12 irradiates the microscopic portion 22 of the sample 20 on the sample holder 14 with an X-ray beam, and the inner diameter of the opening at the tip (that is, the diameter of the X-ray beam irradiation area) is 10 to 100 μm. .

The sample stage 24 of the sample holder 14 is rotated around a φ axis 26 by a φ rotation motor 28 (φ rotation). The base end of the arm 30 supporting the Φ rotation motor 28 is fixed to the rotation shaft 33 of the ω rotation motor 32. The arm 30 is driven by an ω rotation motor 32
The oscillating rotation is performed around the axis 34 in an angle range of 90 degrees (ω rotation). The ω axis 34 is an X-ray beam 36 incident on the sample 20.
On the same straight line as. On the other hand, as shown in FIG. 2, the Φ axis 26 is on the same straight line as the normal 21 of the sample surface in the X-ray irradiating part (the minute part 22 in FIG. 1) of the sample 20. The ω axis 34 corresponds to the first rotation axis in the present invention, and the Φ axis 26
Corresponds to the second rotating shaft in the present invention.

In FIG. 1 and FIG. 4 (front view), the detection surface 17 (inner surface) of the position-sensitive proportional counter 16 is curved, and the center of the curvature is the position of the intersection of the Φ axis 26 and the ω axis 34. It is in. Then, the position of this intersection becomes the X-ray irradiating part (the minute part 22) of the sample 22. Position-sensitive proportional counter 16
Is on a plane 38 (in this embodiment, a vertical plane) that includes the ω-axis 34. This plane 3
Let 8 be called the diffraction plane. The reason is that the diffracted X-ray diffracted on the diffraction plane 38 is detected by the position-sensitive proportional counter 16. The normal to the detection surface 19 of the semiconductor detector 18 is perpendicular to the diffraction plane 38 described above. That is, the semiconductor detector 18 detects fluorescent X-rays emitted in a direction perpendicular to the diffraction plane 38.

In FIG. 2, the surface of the sample 20 is X
The line beam 36 is incident at an incident angle α. Sample 20 is Φ axis 2
Φ rotation around 6. This Φ rotation is a continuous rotation over an angular range of 360 degrees. Since the Φ axis 26 is on the same straight line as the normal 21, the Φ rotation causes the sample 20 to rotate in the plane. Then, when the Φ axis 26 rotates around the ω axis 34, the sample 20 rotates ω around the ω axis 34. This ω rotation is a swing rotation within an angle range of 90 degrees. The surface of the sample 20 is located at the intersection of the Φ axis 26 and the ω axis 34, and the X-ray beam 36 strikes this intersection. Therefore, the X-ray irradiation position on the sample 20 does not change even when the Φ rotation and the ω rotation are performed. The X-ray irradiation area is a minute portion (10 to 100 μm in diameter). Even when the Φ rotation and the ω rotation are performed, since the X-ray incident angle α with respect to the sample 20 is constant, X
The area of the minute portion hit by the line does not change.

FIG. 3A is a plan view of the apparatus of FIG.
FIG. 4A is a front view thereof. In FIG. 3A, the position-sensitive proportional counter 16 disposed above is indicated by an imaginary line, and the components below the position-sensitive proportional counter 16 are indicated by a solid line. In this drawing, the sample holder 14 is in a posture as shown in FIG. That is, the Φ axis 26 is on the diffraction plane 38. In this state, ω = 0 degrees is defined. Then, the direction in which the sample 20 is rotated clockwise while viewing the sample 20 from the X-ray is defined as the positive direction of the ω rotation.

FIG. 3B is a plan view showing a state in which the posture of the sample holder 14 has been changed, and FIG. 4B is a front view thereof. In this case, a plane (which becomes a horizontal plane) including the Φ axis 26 and the ω axis 34 is perpendicular to the diffraction plane 38 (vertical plane). According to the definition of ω rotation described above, the sample holder 14
Is in the state of ω = 90 degrees.

In FIG. 4A, a case where the sample 20 is viewed from the detection surface 17 of the position-sensitive proportional counter 16 (that is, a case where the sample 20 is viewed from above) is considered. FIG.
When the sample 20 is rotated ω by 90 degrees counterclockwise as viewed from the front from the state of (A) (ω = 0 degrees) (that is,
When ω = −90 degrees), the surface of the sample 20 is in a vertical posture. At this time, the sample surface cannot be seen from the detection surface 17 of the position-sensitive proportional counter 16. This time, on the contrary,
When the sample 20 is rotated clockwise by 90 degrees from the state shown in FIG. 4A by ω (when ω = 90 degrees), the surface of the sample also becomes invisible. Therefore, the position-sensitive proportional counter 1
When the sample 20 is viewed from the detection surface 17 of FIG. 6, the condition that the sample surface can be seen is that the ω rotation is within 180 degrees (ω = minus 90 degrees to plus 90 degrees) around the state of FIG.
Degree).

Next, a case where the sample 20 is viewed from the detection surface 19 of the semiconductor detector 18 in FIG. When the sample 20 is rotated by 90 degrees in the counterclockwise direction from the state of FIG. 4B (ω = 90 degrees) (when ω = 0 degrees),
The sample surface becomes invisible. Conversely, when the sample 20 is rotated clockwise by 90 degrees from the state of FIG. 4B by ω (when ω = 180 degrees), the surface of the sample also becomes invisible. Therefore, when the sample 20 is viewed from the detection surface 19 of the semiconductor detector 18, the conditions under which the sample surface is visible are as shown in FIG.
The ω rotation is within the range of 180 degrees (ω = 0 to 180 degrees) around the state of (B).

Therefore, considering the condition that the surface of the sample 20 can be seen from both the detection surface 17 of the position-sensitive proportional counter 16 and the detection surface 19 of the semiconductor detector 18, when the above two conditions are satisfied, that is, ω = 0 to 90 degrees. Therefore, it is most effective to swing and rotate the sample within the range of ω = 0 to 90 degrees to simultaneously detect diffracted X-rays and fluorescent X-rays. Outside this angle range, geometrically, at least one of the position-sensitive proportional counter 16 and the semiconductor detector 18 cannot detect diffracted X-rays or fluorescent X-rays from the sample.

For the above reasons, in the sample holder 14 of this embodiment, the Φ axis 26 changes from the state shown in FIG. 4A (ω = 0 degrees) to the state shown in FIG. 4B (ω = 90 degrees). Swings around the ω-axis 34 within the range up to.

FIG. 5 is an enlarged side view showing the positional relationship between the sample 20 and the X-ray beam 36. The normal 21 of the surface of the sample 20 and the Φ axis 26 are on the same straight line. The X-ray beam 36 is incident on the sample surface at a constant incident angle α. α is 20-30
Set the angle within the range of degrees. X-ray beam 36 and sample 2
The angle β between the zero and the normal 21 is β = (90−α) = 6
0 to 70 degrees. α is set to 20 to 30 degrees for the following reason. When α is reduced, the X-ray irradiation area increases along the X-ray irradiation direction on the sample surface, and there is a possibility that the X-ray beam irradiates other than the target “micro portion”. Therefore, in order to measure only the target minute portion, it is better not to make the incident angle α too small. Conversely, if α is increased, low-angle reflection (reflection with a small diffraction angle) of the X-ray diffracted by the sample 20 is blocked by the sample itself, and the measurement limit of the low-angle reflection increases. . For this reason, in the present invention, α = 20
３０30 degrees is the optimum incident angle. When the sample holder is used, α is kept constant even when the sample is rotated by Φ and ω, so that the optimum incident angle is always maintained.

In the present invention, by employing the arrangement as shown in FIG. 1, even when the semiconductor detector 18 is brought close to the sample 20, the position-sensitive proportional counter 16 and the diffracted X-rays incident on the counter are not affected by the interference. Never do. Therefore, the detection surface of the semiconductor detector 18 can be arranged very close to the sample 20. Thereby, the distance until the fluorescent X-rays generated in the sample 20 reach the detection surface of the semiconductor detector 18 is shortened.
Since fluorescent X-rays from light elements (for example, aluminum and silicon) are easily absorbed by air, the semiconductor detector 18
If the distance to the detection surface can be shortened, the influence of air absorption can be reduced. As described above, in the apparatus of the present invention, even when measurement is performed in the air, the fluorescence X
Lines can be detected.

In the present invention, an imaging plate (also called a stimulable phosphor or a stimulable phosphor) can be used in place of the curved position-sensitive proportional counter. The curved position-sensitive proportional counter used in the above embodiment is a one-dimensional position-sensitive type, but the imaging plate is a two-dimensional position-sensitive X-ray detector.

[0028]

The micropart X-ray analyzer of the present invention optimizes the positional relationship between the micropart of the sample and the X-ray beam by devising the arrangement of the two X-ray detectors and the structure of the sample holder. , X-ray diffraction measurement and X-ray fluorescence analysis measurement on a minute portion of the sample can be performed simultaneously and in a relatively short time.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a side view of the apparatus of FIG.

FIG. 3 is a plan view of the apparatus of FIG. 1;

FIG. 4 is a front view of the apparatus of FIG. 1;

FIG. 5 is an enlarged side view showing a positional relationship between a sample and an X-ray beam.

[Explanation of symbols]

 Reference Signs List 10 X-ray source 12 Collimator 14 Sample holder 16 Curved position sensitive proportional counter 17 Detection surface of curved position sensitive proportional counter 18 Semiconductor detector 19 Detection surface of semiconductor detector 20 Sample 21 Normal 22 Small Part 24 sample stage 26 Φ axis 28 Φ rotation motor 30 arm 32 ω rotation motor 34 ω axis 36 X-ray beam 38 Diffraction plane

Claims (5)

[Claims] 1. A micropart X-ray analyzer comprising the following (a) to (e). (A) An X-ray source that generates an X-ray beam including characteristic X-rays. (B) A collimator that is arranged between the sample and the X-ray source and irradiates a minute part of the sample with an X-ray beam. (C) The angle of incidence of the X-ray beam on the sample surface is 20 to
A sample holder capable of rotating a sample around two rotation axes while holding the sample at a fixed angle within a range of 30 degrees. (D) A position-sensitive first X-ray detector for detecting a diffracted X-ray diffracted by the minute portion of the sample. (E) A second X-ray detector of the energy dispersive type for detecting fluorescent X-rays generated in the minute part of the sample. 2. A first rotation axis of the sample holder is on the same straight line as an X-ray beam incident on the sample, and a second rotation axis of the sample holder is a normal line of the sample surface in the minute portion. 2. The microscopic X-ray analyzer according to claim 1, wherein the second rotation axis rotates around the first rotation axis on the same straight line as that of the micro X-ray analyzer. 3. 3. The method according to claim 1, wherein the first X-ray detector is a curved position-sensitive proportional counter having the minute portion as a center of curvature, and the second X-ray detector is a semiconductor detector. The micropart X-ray analyzer according to claim 2, wherein: 4. The curved detection surface of the position-sensitive proportional counter is on one plane containing an X-ray beam incident on a sample, and the normal of the detection surface of the semiconductor detector is on the plane. 4. The minute portion X according to claim 3, which is vertical.
Line analyzer. 5. The second rotation axis rotates around the first rotation axis so that the sample surface is always visible from both the detection surface of the position-sensitive proportional counter and the detection surface of the semiconductor detector. The micropart X-ray analyzer according to claim 4, wherein the micropart X-ray analyzer rotates in a swinging manner within an angle range of 90 degrees.