JPH11248651A - Microarea x-ray diffractometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make automatically adjustable the position of a microarea in a short time. SOLUTION: In this X-ray diffractometer, an adjustment sample is mounted on a sample stage 1 and a video camera 6 is inserted right under or near the adjustment sample to operate an x-axis and a y-axis with an exterior driving motor so as to set a pattern into the view of the video camera 6 for focusing the sample on its surface with z-axis driving motor. When the adjustment sample has been fixed, the search of a steady point is started, thereby to start the rotation of the sample stage 1 around a ϕ-axis, take an output signal from the video camera for every preset time, recognize a position on the sample corresponding to the position by using an image prior to one frame and find the steady point as the center of rotation in the view of the video camera 6 with computation. Such operation is continued until the steady point is fixed in a range of position error εof the steady point preset by a measuring person, this coordinate position is stored when the steady point is fixed, and the operation for finding the value of the steady point is ended. The sample is changed into a fluorescent plate to position adjust an X-ray source 3 and X-ray is generated from the X-ray source 3 to be radiated to the fluorescent plate for jigging a collimator 4 corresponding to the position of the steady point found by an X-ray emission area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micro area X-ray diffractometer for analyzing the structure of a sample using X-rays.

[0002]

2. Description of the Related Art Conventionally, an X-ray diffractometer has been widely used as a general means for analyzing the crystal structure and the like of a sample. For example, X-ray diffraction of a small region of a sample having a diameter of 10 μm to 1 mm is measured. And X-ray diffraction measurement is performed on a small amount of sample. In such a minute area X-ray diffractometer, by using a collimator or the like having a diameter corresponding to the measurement area, the X-ray is limited to a minute part and irradiated.
In general, X-rays diffracted while the sample is rocked are detected by a detector.

In this micro area X-ray diffractometer, when a desired area is accurately irradiated with X-rays, the X-ray diffraction is accompanied by the swing of the sample.
In order to prevent the irradiation point of the line from moving, the following strict adjustment is performed before the measurement is performed. That is, an ω axis orthogonal to the optical axis of the X-ray incident on the sample, a φ axis orthogonal to the ω axis and orthogonal to the sample surface, and a χ axis orthogonal to both the ω axis and the φ axis. One of the three axes is set as the swing axis of the sample, and while observing the sample surface with a microscope, these three ω axes and φ axes are swung so that a minute portion of the sample to be measured is almost in the microscope field of view. Until it stops moving, the position of the sample is moved spatially for adjustment. By performing such an operation, the measurement minute portion of the sample is positioned at the intersection of the ω axis, φ axis, and χ axis.

[0004]

However, in the above-described conventional example, the work of arranging the minute measurement part at the intersection of the ω axis, φ axis, and χ axis is finely adjusted manually while observing with a microscope. In addition, it is difficult to perform the adjustment with high accuracy, and it takes a considerable time. In addition, when performing measurement after exchanging the sample or after a long period of non-use, a circular adjustment sample is used, and by rotating the sample, a position where the circle is not blurred is searched for, and the center of the position is defined as φ. Although the sample is swung as the rotation center of the shaft, this method has a problem that it takes time for adjustment and it is difficult to set the position accurately.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a micro area X-ray diffraction apparatus that can automatically adjust the position of a micro area in a short time.

[0006]

A small-area X-ray diffractometer according to the present invention for achieving the above object measures the diffraction angle and intensity of diffracted X-rays generated when a sample is irradiated with X-rays. In a micro area X-ray diffraction apparatus for obtaining information on the sample,
Means for generating X-rays, means for limiting the X-ray irradiation area on the sample surface to a minute area, and detection of X-rays diffracted in the X-ray irradiation area to measure the diffraction angle and intensity of the X-rays Means for observing the X-ray irradiation region, an optical observation means for observing the X-ray irradiation region, a three-axis sample rocking mechanism for spatially averaging the orientations of crystals constituting the sample to improve data quality, and The three swing axes of the three-axis sample swing mechanism intersect at one point, and these three axes
An adjustment mechanism that uses an image of the adjustment sample obtained by the optical observation means so that the intersection of the two oscillation axes coincides with the X-ray irradiation area, and the optical observation means Thus, the positions of two or more points in the plane of the adjustment sample can always be recognized.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the illustrated embodiment. FIG. 1 shows a configuration diagram of a micro area X-ray diffractometer. This micro area X-ray diffractometer is used when the sample S is minute or when measuring a minute area of the sample S. X-ray diffraction measurement is performed. Sample S
Is supported by a sample stage 1 that can be translated in a plane, and the sample stage 1 is provided with an x-axis drive motor and a y-axis drive motor for driving a stage (not shown) for parallel translation in an xy plane. And a z-axis drive motor for focusing the surface of the sample S.

The sample stage 1 is held by a large holder 2 rotatable around each of the ω, φ, and χ axes, each of which passes through a minute area in the sample S, and these three axes are orthogonal to each other. ing. Further, an X-ray source 3 for generating X-rays toward the sample S is provided, and a collimator 4 for forming a parallel X-ray beam having a minute cross section is provided at an X-ray outlet. An x-axis drive motor and a y-axis drive motor (not shown) are connected to the collimator 4 so as to irradiate an X-ray beam to a small area of the sample S.

At the position below the sample S, an X-ray detector P
SPC (Position Sensitive P: Position Sensitive P
and a X-ray intensity at each position in the diffraction angle 2θ direction is detected by the PSPC 5. In addition, a video camera 6 is disposed between the sample S and the PSPC 5 as a sample surface observation means. The video camera 6 is driven by a driving device (not shown) and can be inserted immediately below the sample S. It has become. The video camera 6 is used to determine a desired measurement position and to determine a fixed point in the visual field, and is removed from the position in the figure at the time of actual measurement. The output signal of the video camera 6 is connected to a computer provided outside.

FIG. 2 shows a flowchart of the measurement. In the actual measurement, it is necessary to rotate the sample stage 1 around the φ axis and to obtain a fixed point in the visual field. First, the adjustment sample is attached to the sample stage 1 in step (1). As the adjustment sample, a sample in which two or more positions can always be recognized during the swinging operation is drawn as a pattern on a smooth metal material. The adjustment sample performs a calculation on the image output of the video camera 6 in the next process, and thus has a simple shape. In addition, in order to digitize the image output of the video camera 6, the difference in light reflectance is large. It is preferable that the outline of the image be easily extracted.

Subsequently, the video camera 6 is inserted immediately below the sample for adjustment, and the x-axis and the y-axis are operated by the external drive motor so that the pattern comes within the field of view of the video camera 6. Further, focusing of the sample surface is performed using a z-axis drive motor. When the adjustment sample is fixed, step
In (2), a fixed point search is started. When the operation start signal is generated by the measurer's operation, in step (3), the shape of the initial adjustment sample is transferred as an output signal from the video camera 6 to a storage area of an external computer, and the outline of the image is extracted. The image information of the lever is digitized, and rotation of the sample stage 1 around the φ axis is started.

Thereafter, in step (4), an output signal from the video camera 6 is fetched at an arbitrary time interval, and
In (5), the position on the sample corresponding to this position is recognized using the image one frame before, and in step (6), the fixed point which is the rotation center in the visual field of the video camera 6 is obtained by calculation. In step (7), this operation is performed until the fixed point is determined within the range of the fixed position error ε of the fixed point set by the measurer in the range of ± in the x-axis and y-axis directions. The algorithm of the fixed point calculation method may be any method as long as a fixed point can be obtained.

FIG. 3 to FIG. 6 are explanatory diagrams of the fixed point calculating method. First, before rotating the φ-axis, an arbitrary point on the figure drawn in the adjustment sample as shown in FIG. N points P1 to Pn,
In FIG. 3, four points P1 to P4 on the circumference are stored. Angular velocity α rad
Rotation of the φ axis at a rate of P1 per second as shown in FIG.
Assuming that .about.Pn has moved to the points Q1 to Qn after .tau. Seconds, the points Q1 to Qn are stored using the image of the video camera 6 at this point.
Next, Pj, Qj (j = 1, 2,... N) from the temporary origin O
Are calculated, and the value of the line segment PjQj is calculated as shown in FIG. As shown in FIG. 6, the midpoint Rj of the line segment PjQj is obtained.
To calculate the perpendicular bisector of the line segment PjQj.

From the perpendicular bisector of a plurality of midpoints Rj, the intersection
S1j is obtained, and this value is set as the first fixed point candidate coordinates S1j. Subsequently, a plurality of fixed point candidate coordinates are calculated in the above-described procedure, and the position error between the k-th fixed point candidate coordinate Skj and the (k + 1) th fixed point candidate coordinate Sk + 1j is calculated by the equation | Skj.
| − | Sk + 1j | ≦ ε, the value ε preset by the measurer
Repeat until the following.

When the fixed point is determined, the coordinate position is stored in step (8), and the operation for determining the fixed point is completed. In step (9), the sample is converted into a fluorescent plate and the X-ray source 3 is converted. Is adjusted to generate X-rays from the X-ray source 3 and irradiate the fluorescent screen. The collimator 4 is slightly moved so that the X-ray emission area matches the position of the determined fixed point. This operation is X
Although a line is actually generated, the operation is performed while viewing the output image of the video camera 6 from the outside in a state of being covered with the X-ray protection cover, so there is no possibility of being exposed.

After that, in the same manner as in a normal measuring method,
A single crystal silicon powder, which is a standard sample having a known diffraction angle, is placed on the sample stage 1, and the diffraction pattern is measured while oscillating each axis, and datum of the PSPC 5 is performed. Note that the adjustment sample, the fluorescent plate, and the standard sample are installed on one sample stage, and all operations can be performed by automatically exchanging them, but it is also possible to partially operate them manually.

FIG. 7 shows a side view of the measurement sample S. A minute area on the quartz substrate 11 has a diameter of about 120 μm and a thickness of about 1 μm.
A 0 nm palladium oxide thin film 12 is formed, and a measurement sample S
And In order to perform X-ray diffraction measurement of a minute area of the palladium oxide thin film 12 in the sample S, gold (A) as shown in FIG.
u) An adjustment sample S ′ in which a circle 14 having a diameter of 50 μm is engraved on 13 and points P1 to P8 for identification on the circumference thereof is used.

The adjustment sample S 'is fixed to the sample stage 1, and the video camera 6 is disposed immediately below. While observing the output signal of the video camera 6 using a CRT (not shown), focusing is performed using a driving device connected to the sample stage 1 for performing focus adjustment. The image at this point has been transferred to the storage area of the external computer in advance, and 8 points on the circumference
A fixed point is calculated using P1 to P8 as calculation points.

Subsequently, the sample stage 1 is swung around the φ axis at an angular velocity of π / 6 rad / sec, and a circle 14 stored in advance is used.
A first fixed point search is performed using the upper points P1 to P8 and the points Q1 to Q8 two seconds later. Next, a second fixed point search is performed using the point after 2 seconds and the point after 4 seconds, and finally a total of 5 searches are performed every 2 seconds, and the fixed point has a position error of ± 5 μm. It can be obtained as follows.

As the X-ray source 3, a rotating cathode X-ray tube using copper as a cathode is used.
It is driven at kV and a tube current of 300 mA. The X-ray focus is a point focus, the effective focus width is 1 mm and the length is 1 m
m, and the collimator 4 having a diameter of 50 μm is used.

Next, a fluorescent plate is set on the sample stage 1, and the fluorescent plate is irradiated with X-rays generated under the above-mentioned conditions while observing the output signal of the video camera 6 on an external CRT. In this state, the light emitting region by the X-ray irradiation is immediately moved to the position of the fixed point determined in the previous step, and then the silicon powder sample is set on the sample stage 1 and the datum of the PSPC 5 is executed.

After all the above adjustments are completed, the sample S
Is placed on the sample stage 1, and the X-rays generated from the X-ray source 3 pass through the collimator 4 and irradiate the palladium oxide thin film 12 in a small area in the sample S. The measurement was performed on the ω axis at 45.
The intensity of the diffracted X-rays is detected by the PSPC 5 by rotating from φ to 60 °, rotating the φ axis counterclockwise at a constant speed, and swinging the χ axis in a range of ± 5 °. An X-ray diffraction pattern having a diffraction angle 2θ in the range of 20 ° to 80 ° can be recorded in one hour measurement, and the diffraction peak of the palladium oxide thin film 12 can be observed.

FIG. 9 shows a plan view of another adjustment sample S '. The same measurement sample as in the first embodiment was used,
As the adjustment sample S ′, a sample in which two circles 15 a and 15 b having different radii are engraved on the gold 13 at a distance of about 50 μm is used.

The adjustment sample S ′ is fixed to the sample stage 1, and the video camera 6 is disposed immediately below.
While observing the output signal of the sample stage using a CRT, focusing is performed using a drive device for performing focus adjustment connected to the sample stage 1. At this time, the center P1, P2 and the center P1, P1, P2 of the first and second circles 15a, 15b are transferred in advance to the storage area of the external computer to obtain a fixed point.
A total of three intersection points P3 between the line connecting P2 and the first circle 15a are set as calculation points.

Subsequently, the sample stage 1 is swung around the φ axis at an angular velocity of π / 6 rad / sec, and the calculation points P1 to P3 stored in advance are set.
A first fixed point search is performed using the point and the points Q1 to Q3 two seconds later. Next, a second fixed point search is performed using the point after 2 seconds and the point after 4 seconds, and finally a total of 5 searches are performed every 2 seconds to determine the fixed point with a position error of ± 5 μm. It can be obtained as follows. The measurement of the diffraction pattern is performed in the same manner as in the first embodiment.

FIG. 10 shows a plan view of still another adjustment sample S '. The same measurement sample as that of the first embodiment was used. As the adjustment sample S ′, one side of 50
One in which three circles 16a to 16c having different radii centered on the vertexes of a regular triangle of μm are engraved is used. The adjustment sample S ′ is fixed to the sample stage 1 and the video camera 6
Is placed directly below.

While observing the output signal of the video camera 6 using a CRT, focusing is performed using a drive device for performing focus adjustment connected to the sample stage 1. The image at this point is previously transferred to the storage area of the external computer, and each circle 16a to 16c
Are the calculation points.

Subsequently, the sample stage 1 is swung around the φ axis at an angular velocity of π / 6 rad / sec, and the points P1 to P3 stored in advance and the points G1 to G3 two seconds later are used. A first fixed point search is performed, and then a second fixed point search is performed using the point after 2 seconds and the point after 4 seconds. Finally, a total of three searches are performed every two seconds, and the fixed point can be obtained with a position error of ± 5 μm or less. The measurement of the diffraction pattern is performed in the same manner as in the first embodiment.

FIG. 11 shows a plan view of still another adjustment sample S '. The same measurement sample as in the first embodiment is used,
As the adjustment sample S ′, four circles 17a having different radii centered on the vertices of a square having a side of 50 μm on the gold 10
１７17d is used. The adjustment sample is fixed to the sample stage 1, and the video camera 6 is disposed immediately below.

While observing the output signal of the video camera 6 on a CRT, focusing is performed using a driving device connected to the sample stage 1 for performing focus adjustment. The image at this time is previously transferred to the storage area of the external computer, and the four points P1 to P4 at the center of each of the circles 17a to 17d are calculated in order to obtain fixed points.

Subsequently, the sample stage 1 was swung around the φ axis at an angular velocity of π / 6 rad / sec. The first fixed point search is performed using the points P1 to P4 stored in advance and the points G1 to G4 two seconds later, and then the second fixed point search is performed using the points two seconds and four seconds later. Is performed. Finally, a total of three searches are performed every two seconds, and the fixed point can be obtained with a position error of ± 5 μm or less. The measurement of the diffraction pattern is performed in the same manner as in the first embodiment.

[0032]

As described above, the micro area X-ray diffraction apparatus according to the present invention uses the three-axis sample rocking mechanism to reduce the required micro area before starting the X-ray diffraction measurement of the micro area. By performing all the alignment adjustments automatically, the adjustment work can be completed in a short time and accurate and efficient X-ray diffraction measurement can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a micro area X-ray diffraction apparatus.

FIG. 2 is a flowchart of a measurement.

FIG. 3 is an explanatory diagram of a fixed point calculation method.

FIG. 4 is an explanatory diagram of a fixed point calculation method.

FIG. 5 is an explanatory diagram of a fixed point calculation method.

FIG. 6 is an explanatory diagram of a fixed point calculation method.

FIG. 7 is a side view of a measurement sample.

FIG. 8 is a plan view of an adjustment sample.

FIG. 9 is a plan view of another adjustment sample.

FIG. 10 is a plan view of still another adjustment sample.

FIG. 11 is a plan view of still another adjustment sample.

[Explanation of symbols]

 Reference Signs List 1 sample stage 2 large holder 3 X-ray source 4 collimator 5 PSPC 6 video camera 11 quartz substrate 12 palladium oxide thin film 13 gold S measurement sample S 'adjustment sample

Claims (4)

[Claims] 1. Diffraction X generated when a sample is irradiated with X-rays
In a micro area X-ray diffraction apparatus that obtains information on the sample by measuring the diffraction angle and intensity of a line, a means for generating X-rays, a means for limiting an X-ray irradiation area on the sample surface to the micro area, Means for detecting X-rays diffracted in the X-ray irradiation area and measuring the diffraction angle and intensity of the X-rays, optical observation means for observing the X-ray irradiation area, and a crystal constituting the sample Sample oscillating mechanism for spatially averaging the orientations of the three axes to improve data quality, and three oscillating axes of the three-axis sample oscillating mechanism intersect at one point, and these three oscillating axes And an adjustment mechanism that uses an image of the adjustment sample obtained by the optical observation means in order to make the intersection of the X-ray irradiation area coincide with the X-ray irradiation area. The position of two or more points in the plane of the sample can always be recognized. Small area X-ray diffractometer. 2. The small area X-ray diffraction according to claim 1, wherein the adjustment sample has a region having different light reflectivity, and is a polygon in which a positional relationship between the two or more points can be always recognized. apparatus. 3. The micro area X-ray diffraction apparatus according to claim 1, wherein the adjustment sample has regions having different light reflectivities, and is composed of a plurality of circular patterns having different sizes. 4. The small-area X-ray diffraction apparatus according to claim 1, wherein said optical observation means includes a video camera.