JPH1048159A - Method and apparatus for analyzing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously analyze a two-dimensional structure parallel to a sample face of atomic structure or the like, and change information of the structure in a depthwise direction in a short time, by inputting X rays within a specific range of angles to the sample face and detecting diffracted X rays by a two-dimensional detector. SOLUTION: A sample 11 is set on a holder 1 so that a surface of the sample 11 is perpendicular to a rotary shaft of an angle control part 2. The angle control part 2 rotates the holder 1 around a z-axis, and an angle control part 3 sets a two-dimensional detector 5 at an optional position in the circumference of the rotary shaft of the angle control part 2. An angle control part 4 rotates the whole of the holder 1 and angle control parts 2, 3 to entering X rays thereby controlling an angle of incidence of X rays to the sample 11. X rays are projected when the angle α of incidence to the face of the sample 11 from an X-ray source 12 is limited to be 0 deg.<α<5 deg.. While a diffraction angle 2θ of the detector 5 is changed by the control part 3, an intensity of diffracted rays is measured. In this manner, both a periodicity in two-dimensional directions and information in a depthwise direction in the face of the sample and be measured at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of irradiating a sample with X-rays and detecting a spatial distribution of energy, diffraction direction and intensity of the diffracted X-rays obtained by a diffraction phenomenon from the sample. The present invention relates to a structure analysis method and a structure analysis apparatus for analyzing an electronic structure and an atomic structure, and is particularly suitably applied to the analysis of the structure of the surface of a sample, the vicinity of the surface, and the interface near the surface.

[0002]

2. Description of the Related Art The X-ray diffraction method has a variety of measurement atmospheres and can be observed on the spot, as compared with the electron beam diffraction method which is one of the other main structural analysis methods. It has the advantage that the quantitative analysis of the diffraction intensity is relatively easy because the multiple scattering is small, so that precise structural analysis is easy.

As a method of applying the X-ray diffraction method having such advantages to, in particular, structural analysis near the surface, X-rays are incident on the sample at a small angle of several degrees, and X-rays are applied to the sample. A grazing incidence X-ray diffraction method in which the penetration depth is made relatively small and the diffraction intensity from the vicinity of the surface is increased has been used.

In such a conventional grazing incidence X-ray diffraction method, X-rays diffracted in a direction in a plane perpendicular to or close to the sample surface are detected. In order to detect the X-rays, measurement was performed while rotating a zero-dimensional or one-dimensional detector in a plane perpendicular to or close to the surface of the sample. Further, when measuring using a two-dimensional detector, it is necessary to use a goniometer rotatable in the in-plane direction and a special screen, and to limit the angle of emission of the diffraction line. Kaihei 6-2
No. 22017).

[0005]

The conventional grazing incidence X-ray diffraction method for examining the structure of the surface of a material is described as follows. As shown in FIG. 7, (a) the scattering vector is in a plane perpendicular to the sample surface. Optical system (hereinafter referred to as surface optical system (I)) (b) There are two kinds of measurement methods of an optical system having a scattering vector in the plane (hereinafter referred to as surface optical system (II)). . These features are shown in Table 1 below.

[0006]

[Table 1]

In the surface optical system (I), the incident angle of the X-ray is limited to several degrees, and the detector is scanned in a plane almost perpendicular to the surface. The information obtained as a result is information on a bulk region near the surface, that is, average information on a thick region having a surface depth of several μm;

On the other hand, the surface optical system (II), X-ray incident angle of the critical angle alpha _c vicinity to the fixed sample, scanning the detector surface in nearly parallel to plane. The information obtained as a result is information on the two-dimensional structure in the in-plane direction of the outermost surface (100 ° or less; 20 atomic layers or less), that is, information on the in-plane atomic arrangement in the outermost surface region having a very small surface depth.

However, in the conventional method of scanning and measuring a zero-dimensional detector with the surface optical system (I) of the grazing incidence X-ray diffraction method, it is necessary to scan the detector in a plane perpendicular to the surface. Since the direction of the periodicity observed differs depending on the diffraction angle, quantitative analysis is difficult when the crystal grains near the surface are preferentially oriented in a specific direction.

Furthermore, there are many problems in measuring a weak signal. This is because, compared to the ordinary bulk X-ray diffraction method, the surface diffraction method in which the incident angle α is fixed to a small angle has a smaller number of atoms in the surface layer contributing to diffraction, the diffraction intensity is extremely weak, and the signal intensity is lower. / Background ratio (S /
B ratio) is small.

Further, in order to examine structural changes at different depths, it is necessary to change the incident angle α, and a longer measurement time is required.

A method of scanning a two-dimensional detector with a conventional surface optical system (I) for measurement (Japanese Patent Laid-Open No. Hei 6-2).
Also in Japanese Patent No. 22017), since it is necessary to use a special screen and measure the diffraction beam at a limited angle, only one part of the diffraction line that can be measured at a time can be measured at a time. Cannot be measured simultaneously. Therefore, when the measurement requires a long time, the structure of the sample changes during the measurement (for example, a reaction with moisture in the atmosphere), and precise structural analysis is impossible.

On the other hand, in the conventional surface optical system (II), 0
The measurement is performed by scanning a two-dimensional detector, and when measuring a weak signal, the measurement time is very long, the structure may change during the long time measurement, it spreads in three dimensions There are many problems such as difficulty in distinguishing from the noise background because one point of the diffraction line is measured. This is because, compared to the ordinary bulk X-ray diffraction method, the surface diffraction method in which the incident angle α is fixed to a small angle has a smaller number of atoms in the surface layer contributing to diffraction, the diffraction intensity is extremely weak, and the signal intensity is lower. This is because the background ratio (S / B ratio) is small. Therefore, it took a long time to measure accurate diffraction data.

For example, the surface of a single crystal gold (001) is irradiated with an incident angle α using an enclosed X-ray generator with a power of 2 kW.
In the conventional surface diffraction method in which the measurement is performed by scanning a zero-dimensional detector such as a scintillation counter in a plane substantially parallel to the surface, and measuring the diffraction peak in the vicinity of the critical angle α _c , it takes one day to measure one diffraction peak. Need more time,
It takes several days to measure all diffraction peaks for identification of the surface structure. Further, when the S / B ratio is still smaller, such as in the case of an amorphous substance or a trace content, it is often impossible to detect a diffraction line by such a method even if measurement is performed for a long time. For this reason, not only quantitative analysis but also qualitative crystal structure identification has been a major problem.

Further, in both the conventional surface optical system (I) and the surface optical system (II), a problem common to the case where the measurement is performed by scanning a 0-dimensional detector is that the crystal grains are oriented in a specific direction. Measurements with preferentially oriented materials are very difficult or impossible. this is,
If the material is polycrystalline (the crystal orientation is random), the diffraction line can be measured even if the detector is scanned in any direction. This is because the line appears only in a specific direction, and even if scanning is performed in a specific direction, the diffraction line cannot be captured unless it coincides with the direction in which the diffraction line appears. However, there are many cases where preferential orientation is observed in the crystal grains on the surface of such a material. As such a material, there is an epitaxially grown thin film which is influenced by the crystal structure of the substrate when the film is grown and grows in a preferential crystal orientation having consistency with the crystal structure of the substrate. Such an epitaxial film is often present in electronic materials, and its analysis by surface analysis is extremely important.

Further, the surface optical system (I) can be obtained by a grazing incidence X-ray diffraction method using a conventional dimensional or one-dimensional detector.
In order to perform the measurement of the surface optical system (II) with a single diffraction device, it is necessary to use a large-scale structural analysis system because the manner of scanning by the detector is completely different. In addition, since it is impossible in principle to measure different diffraction lines using the conventional method, it is inevitable to examine each information separately. It was difficult to observe any significant changes.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and is intended to reduce the spatial distribution of the energy, diffraction direction, and diffraction intensity of diffracted X-rays obtained by the diffraction phenomenon from the material surface. In the detection method, a two-dimensional structure parallel to the sample surface, such as the atomic structure and electronic structure of the surface of the sample and the interface near the surface, and information on changes in the depth direction are simultaneously analyzed in a short time and with high accuracy. An object of the present invention is to provide an analysis method and a structure analysis device.

[0018]

According to the present invention, as a result of diligent studies to solve the above-mentioned conventional problems, the angle of incidence of X-rays on a sample is limited, and a two-dimensional detector is used as a detector. By using, and if necessary, moving the two-dimensional detector in the in-plane direction parallel to the sample surface and measuring again, diffraction lines from the surface can be measured efficiently in a short time,
In addition, it was found that the information on the two-dimensional structure parallel to the sample surface and the change in the depth direction can be measured simultaneously. The present invention
This is based on this finding.

According to the structure analysis method of the present invention, a sample is irradiated with X-rays, and the energy of X-rays diffracted from the sample and / or
Or analyzing the structure of atoms and / or electrons of the sample by detecting the spatial distribution of diffraction intensity,
The angle α between the incident X-ray and the surface of the sample is 0 ° <α ≦
This is a technique in which X-rays are incident within a range of 5 ° and diffracted X-rays are detected by a two-dimensional detector.

In one embodiment of the structure analysis method of the present invention, when α _c is the critical angle of the sample with respect to the incident X-ray, the angle α between the incident X-ray and the sample surface is 0 ° <α ≦ 2α.
The value must be within the range of _c .

In one embodiment of the structural analysis method of the present invention, the operation of moving the two-dimensional detector in an in-plane direction parallel to the surface of the sample and measuring again is repeated.

The structure analyzing apparatus of the present invention irradiates a sample with X-rays, and obtains energy and / or energy of X-rays diffracted from the sample.
Or for analyzing the structure of atoms and / or electrons of the sample by detecting the spatial distribution of diffraction intensity, wherein the angle α between the incident X-ray and the surface of the sample is 0 °.
This is an apparatus that can make X-rays incident within the range of <α ≦ 5 ° and detects X-rays diffracted from the sample by a two-dimensional detector.

In the structure analyzing apparatus of the present invention, the surface of the sample is x
When setting the x, y, z orthogonal coordinate system to be within the y plane, rotate the sample around each of the x, y axes, and in the directions of the x, y, z axes. A sample holder that can be translated, a two-dimensional detector that detects diffracted X-rays generated from the sample when the sample is irradiated with X-rays, and a second unit that rotates the sample holder around the z-axis. A first angle control unit and the two-dimensional detector are coupled to each other, and a second angle control for disposing the two-dimensional detector at an arbitrary position around a rotation axis of the first angle control unit Part, a third angle controller for rotating the sample holder, the first and second angle controllers about an axis orthogonal to the z-axis, the two-dimensional detector, and the first and second detectors. And a control unit for controlling the third angle control unit.

[0024]

The object of the present invention can be achieved for the following reasons.

By limiting the incident angle of the X-ray, the penetration depth of the X-ray can be kept extremely small. And
A two-dimensional detector uses a diffraction line containing information from the periodicity in the depth direction (surface diffraction line: referred to as _ID ) and a diffraction line containing information from the periodicity in the surface direction (surface diffraction line: I _P). ) Are measured at the same time. Two-dimensional detector to the measured diffraction lines are the aggregate containing both components of surface diffraction lines I _D and I _P, the ratio of the depth and the surface in the direction information is variously mixed Diffraction lines can be measured simultaneously.

Specifically, the direction parallel to the sample surface is I _P
Only the component, the perpendicular direction to the sample surface and the direction perpendicular thereto is only the _ID component, and the other directions are regions where both are mixed at various ratios. That is, the intensity distribution obtained by the two-dimensional detector is a function F ( _ID , _IP ) using two types of information (the periodicity in the depth direction and the periodicity in the in-surface direction) of the sample surface as variables. Corresponding to Then, by converting the diffraction intensities I _D and I _P from the diffraction theory to the structures, the structures in various depths and in-plane directions can be determined.

In order to obtain a wider range of information, a two-dimensional detector is arranged at a specific position for measurement, and then the two-dimensional detector is moved in an in-plane direction parallel to the sample surface to measure again. I do. By repeating this operation, sufficient information will be gathered to reveal structures in the in-plane direction at various depths.

[0028]

Embodiments of the present invention will be described below.

In the surface diffraction method, the X-ray incident angle α is limited to a value within the range of 0 ° <α ≦ 5 ° (hereinafter referred to as “incident condition 1”) for the following reason.

D is the distance between the surfaces causing diffraction and α is the incident X
Assuming that the angle between the line and the sample surface is made, the sample 11 of the incident X-ray
The medium optical path length l is represented by l∝d / cos (α). Therefore, in order to emphasize the information near the surface, the incident depth of the X-ray may be limited, and the path (optical path) until the X-ray is completely attenuated may be limited to the vicinity of the surface. When the incident angle α of the X-ray is limited to 0 ° <α ≦ 5 °, information near the surface is enhanced 10 times or more as compared with a normal 2θ-θ optical system, so that it is necessary to achieve the object. It is a requirement.

[0031] In the surface diffraction method, in particular, limit the incidence angle alpha of the X-ray in the range of 0 ° <α ≦ 2α _c (hereinafter, referred to as incident condition 2) is given to the following reason.

In order to investigate the two-dimensional structure in a region near the surface more than the incident condition 1, it is necessary to further limit the X-ray incident depth and to detect diffraction lines from the two-dimensional structure in the surface. is there. For this purpose, it is necessary to keep the incident angle α close to the critical angle α _c at which the incident light is totally reflected by the surface.
Under such conditions, the incident X-rays are totally reflected, the penetration depth of the incident rays into the sample 11 is about 100 ° (about 20 atomic layers) or less, and the enhancement effect due to the interference between the incident X-rays and the diffracted X-rays Thus, information on the two-dimensional structure of the outermost surface can be measured by the surface optical system (II).

In the surface diffraction method, the reason why the incident angle α of X-rays is kept at 2α _c or less is that at a larger angle, the penetration depth into the sample 11 becomes sharply large and the diffraction X This is because the emphasis effect due to the line interference is significantly reduced. The lower limit of the incident angle α is larger than 0 ° because measurement becomes impossible below this value. Also,
And if the sample 11 surface is not completely flat, if it is composed of a plurality of layers may be employed a critical angle by the weighted average of the surface roughness and a plurality of layers as the critical value alpha _c.

Since the X-ray incident depth can be limited by using the method of the incident condition 1 or the incident condition 2, the structure of the surface / interface can be reduced by detecting the diffraction line from the X-ray under the condition. Can be analyzed. Under the incidence conditions of this embodiment, as described above, the penetration depth of X-rays is sufficiently small, and only signals on the surface can be effectively extracted. Therefore, there is no need to use a special screen, which has been conventionally required (Japanese Patent Laid-Open No. 6-222017), or to perform measurement by limiting the emission angle of diffraction rays.

As the two-dimensional detector, for example, an imaging plate or a CCD camera is used. In the case of an imaging plate, it may be convenient to simultaneously perform measurement while monitoring with a detector such as a scintillation type. When an imaging plate or the like is used as a two-dimensional detector, it is effective to bend the reciprocal lattice space in order to measure it without distortion.

This analysis method will be described with reference to a specific structure analysis apparatus. FIG. 1 illustrates this structural analysis apparatus.

This structural analysis apparatus comprises a sample holder 1 and
Angle control units 2 to 4, two-dimensional detector 5, control unit 6
And an arm 7.

The sample holder 1 holds the sample 11 and controls the direction and the position of the sample 11 with respect to the incident X-ray. As its function, when taking a rectangular coordinate system of x, y, z so that the surface of the sample 11 is in the xy plane, the sample 11 is rotated around each of the x, y axes, and y,
It can be translated in the direction of each axis of z. The sample holder 1 is installed on a rotation center axis (z axis) of the angle control unit 2.

The angle control unit 2 has a function of rotating the sample holder 1 around the z-axis, and is installed on the angle control unit 3.

The angle control section 3 is for installing the two-dimensional detector 5 at an arbitrary position around the rotation axis of the angle control section 2. Normally, the two-dimensional detector 5 may be installed on the arm 7 extending vertically from the rotation axis. It is desirable that the length of the arm 7 be variable depending on measurement conditions. Usually, as the length of the arm 7 increases, the measurement accuracy of the diffraction line improves, but on the other hand, the range that can be measured by the two-dimensional detector 5 at a time decreases, and the measured diffraction intensity decreases. As for the method of connecting the arm 7 and the two-dimensional detector 5, the two-dimensional detector 5 may be simply attached in a direction perpendicular to the arm 7. In order to further improve the measurement accuracy of the diffraction intensity, the two-dimensional detector 5 may be arranged on a locus that draws an arc in a direction perpendicular to the arm 7. With this arrangement, diffraction X-rays can be measured without distortion. In order to realize this arrangement, as shown in FIG. 2, a curved rail 8 having a shape of a locus that draws an arc in a direction perpendicular to the arm 7 is installed at the tip of the arm 7, and two curved rails 8 are placed on the curved rail 8. What is necessary is just to be able to move and arrange the dimensional detector 5. Alternatively, the two-dimensional detector 5 may be installed on a curved rail 8 orthogonal to the arm 7 and a rotator installed at the tip of the curved rail 8.

The angle controller 4 rotates the whole of the sample holder 1, the angle controller 2, and the angle controller 3 with respect to the incident X-ray, and thereby controls the incident angle of the X-ray to the sample 11. I do.

The two-dimensional detector 5 is, for example, an imaging plate or a CCD camera. In the case of an imaging plate, as shown in FIG. 3, a scintillation detector 9 is installed and measurement is performed while monitoring diffraction lines. Sometimes it is convenient. When an imaging plate is used as the two-dimensional detector 5, it is effective to bend and attach the reciprocal lattice space for measurement without distortion.

The controller 6 controls the angle controllers 2 to 4 and the two-dimensional detector 5.

In order to analyze the surface structure of the sample 11 using the structure analyzing apparatus having such a configuration, first, the sample 11 is placed on the sample holder 1 and the surface of the sample 11 is perpendicular to the rotation axis of the angle control unit 2. Installed so that After that, the sample 1 is irradiated with the incident X-ray so that the position to be measured on the sample 11 is irradiated.
The position 1 is set by the parallel movement of the sample holder 1.

For measurement with the surface optical system (I), the surface of the sample 11 is arranged by the angle control unit 2 so as to be parallel to the z-axis (the rotation axis of the angle control unit 3). Then, after setting the incident angle α to a target angle by the angle controller 4, the sample 11 is irradiated with incident X-rays, and measurement is performed while changing the diffraction angle of the two-dimensional detector 5 by the angle controller 3.

Another method of measuring with the surface optical system (I) is to leave the sample 11 set so that its surface is perpendicular to the rotation axis of the angle control unit 2, and instead use the angle control unit. 3 scans the two-dimensional detector 5 in addition to rotation parallel to the surface of the sample 11 (that is, rotation around the rotation axis of the angle control unit 2), and rotation around an axis perpendicular to the rotation (2θ). ') Is a way to do this. In this case, it is desirable to measure with the detector angle 2θ = 0 ° (see FIG. 1) from the viewpoint of obtaining a high intensity. However, when the orientation of the crystal plane to be measured is significantly deviated from the surface of the sample 11, Angle 2θ at which the diffraction intensity is maximized
The measurement may be performed at. In this measurement, the angle of 2θ ′ corresponds to the diffraction angle.

The rotation of 2θ ′ may be added to the angle controller 3 as its function, or a straight or curved arm perpendicular to the arm 7 is disposed at the tip of the arm 7 extending from the angle controller 3. Then, the latter arm may be scanned by the two-dimensional detector 5.

In order to measure with the surface optical system (II),
As described above, the sample is set so that its surface is substantially perpendicular to the rotation axis of the angle control unit 2. Thereafter, in order to determine and control the incident angle α and the outgoing angle α ′ with high accuracy, the detector angle 2θ = 0 ° and the detector angle α ′
The angle may be obtained based on the critical angle α _c obtained by measuring the reflectance while changing the angle.

After that, the incident X-ray is irradiated, and the intensity of the diffraction line is measured while changing the diffraction angle 2θ of the two-dimensional detector 5 by the angle control unit 3.

The measurement method in the surface optical system (I) and the surface optical system (II) has been described above. However, since the two information of the surface optical system (I) and the surface optical system (II) are measured at the same time. In this case, the two-dimensional detector 5 may be installed in a direction including the surface of the sample, and simultaneously observe a diffraction line in a direction parallel to the sample surface and a diffraction line in a direction perpendicular to the sample surface (details will be described later). I do.)

Until now, the crystal surface and the sample surface have been referred to as “sample surface” as being exactly coincident with each other, but in an actual sample, there is an angle deviation between them. In this case, the crystal plane is changed to Bragg by the sample holder 1 or the angle controllers 2 to 4.
The difference may be corrected so as to satisfy the condition.

The measurement is performed by the method described above. Among them, how the conventional problem is solved by using the two-dimensional detector will be described below.

The reason why the measurement time is greatly reduced when a two-dimensional detector is used is as follows. In a conventional method of scanning a zero-dimensional detector (for example, a scintillation detector) while changing the diffraction angle (2θ or α ′),
Measuring a wide range of information in reciprocal lattice space is very time consuming. To give a standard example, 10cm x 10c
When a two-dimensional detector of m is placed at a distance of 20 cm from the sample and measured, a 0400-dimensional detector is used to scan at a step angle of 0.1 ° in order to obtain equivalent data. It is necessary to measure points. That is, although it depends on the sensitivity difference between the two-dimensional detector and the point-type detector, the measurement in a time shorter than 1/1000 or more using the two-dimensional type detector is more difficult than the point-type detector. It is possible. For the same reason, a two-dimensional type detector can perform measurement in 1/100 or more times shorter than a one-dimensional type detector.

Further, the reason why a weak signal can be detected by a two-dimensional detector is that information can be analyzed by a two-dimensional information pattern recognition method. It is extremely difficult to analyze the scattering from a very weak surface.
It is difficult to recognize scattered radiation only from measurement by scanning in a certain one-dimensional direction. However, by forming a two-dimensional pattern of the scattered intensity in all directions in the space measured simultaneously by the two-dimensional detector, it becomes possible to measure a minute signal which cannot be determined by the conventional method.

The reason why the two-dimensional detector is easy to measure even when the preferential orientation of the crystal grains on the surface is observed is as follows. In order to detect a diffraction line, it is necessary to scan the direction in which the diffraction line is observed with a detector, but this direction is different even for the same structure. In this case, it becomes ring-shaped. That is,
In the case of a single crystal, it is possible to obtain a specific orientation by calculation, and in the case of a polycrystal, it is possible to cross the ring regardless of the scanning direction, so a point-type detector is used. Measurement is also easy. If there is a preferential orientation of crystal grains, the diffraction line ring will be discontinuous, so it is necessary to scan with a point-type detector in anticipation of the azimuth where the diffraction line is found, making measurement very difficult. Become. On the other hand, in the two-dimensional detector, since a certain direction is measured at the same time, the measurement can be performed even when there is a preferential orientation of the crystal grains.

When a two-dimensional detector is used, in-situ observation is possible because all measurement points can be measured simultaneously and in a short time. Therefore, when the structure of the sample changes during the measurement (for example, reaction even at a high temperature), there is a problem that the structure is different between the initial stage and the final stage of a scan that occurs when measuring using a point-type or linear detector. Can be avoided.

When a two-dimensional detector is used, it is possible to simultaneously measure two pieces of information of the surface optical system (I) and the surface optical system (II), which were impossible with the conventional method. By installing a two-dimensional detector in a direction including the sample surface, diffraction lines in a direction parallel to the sample surface and diffraction lines in a direction perpendicular to the sample surface are observed at the same time. This is because measurement is possible. Then, by combining the periodicity in the two-dimensional direction in the surface and the information in the depth direction, three-dimensional (three-dimensional) information at different depths on the surface and near the surface can be obtained.

As a specific arrangement of the optical system, the optical system is arranged so as to be measured by the above-mentioned surface optical system (II). That is,
The sample is set so that its surface is perpendicular to the rotation axis of the angle control unit 2, and the two-dimensional detector is installed so as to include the surface of the sample and also include components perpendicular to the surface. Thereafter, the angle of incidence α and the angle of emission α ′ are set to target angles by the angle control unit 3 and the angle control unit 4. And
A diffraction line in a direction parallel to the sample surface and a diffraction line in a direction perpendicular to the sample surface may be simultaneously observed.

In order to obtain a wider range of information on the two-dimensional structure, the intensity of the diffraction line is measured after the measurement while changing the diffraction angle 2θ of the two-dimensional detector 5 by the angle control unit 3. Also, to obtain information on the structure in the depth direction over a wider range,
The angle of incidence α may be increased by the angle controller 4, and at the same time, the two-dimensional detector 5 may be scanned on the arm 7 to measure a diffraction line for a larger emission angle α ′.

As a process of analyzing the obtained result, there is the following method. The measured diffraction line is a diffraction line containing information from the periodicity in the depth direction (surface diffraction line: _ID ).
And a diffraction line (surface diffraction line: I _P ) including information from the periodicity in the in-surface direction. Therefore, when a virtual two-dimensional space having these as two components is introduced, a change in the depth direction of the structure near the surface can be expressed by a function f ( _ID , _IP ). Then, by allocating all the measured diffraction lines to this space and analyzing the space, it is possible to determine the structures in various depths and in the direction of love.

Of course, it is also possible to obtain information on structures at different depths by changing the angle α.
More detailed information can be obtained by continuously measuring the angle α with the two-dimensional detector 5 for each of the plurality of angles α.

By obtaining such information in the depth direction, when there are a plurality of surface thin films near the surface, information on the structure of each layer and the interface structure between these layers can also be obtained. Generally, when there are multiple interfaces, their critical angles α _c are different. Therefore, by examining the structure of each layer and the interface with respect to the corresponding incident angle and diffraction angle, the structure of a plurality of interfaces can be examined simultaneously and nondestructively.

It is unnecessary to use a special screen, which is required in the prior art (JP-A-6-222017), or to limit the angle of emission of the diffracted rays. This is because, under the incidence condition, the penetration depth of the X-ray is sufficiently small as described above, and only the signal on the surface can be effectively extracted.

[0064]

EXAMPLES Hereinafter, some examples of the present invention will be described.
Description will be made based on comparison with a comparative example.

Example 1 A film thickness of about 500 was formed on a silicon single crystal substrate by magnetron sputtering evaporation.
A pure iron thin film having a thickness of 1 nm is formed, and then a sample 11 is prepared in a state where a natural thin film of Fe ₂ O ₃ (iron oxide layer) having a thickness of about 1 nm is formed on the pure iron thin film. Then, a monochromatic X-ray of 8 keV was incident on the sample 11 at an incident angle α = 1 °, and measurement was performed using an imaging plate as the two-dimensional detector 5. FIG. 3 shows the measurement results. Although the crystal grains of the iron oxide layer near the surface are oriented in a specific direction, diffraction lines can be clearly confirmed. The measurement time was 90 seconds.

(Comparative Example 1) Using a sample similar to that of Example 1, measurement was performed by scanning a scintillation counter as a 0-dimensional detector under the same measurement conditions. FIG. 4 shows the measurement results. Here, the scanning direction corresponds to the direction indicated by the broken line in FIG. 3 in the first embodiment. Since the crystal grains of the iron oxide layer near the surface are oriented in a specific direction, no diffraction line can be confirmed (the arrow in FIG. 4 indicates the position of the diffraction line predicted from the calculation). The measurement time was 30 hours.

(Example 2) The same sample as in Example 1 (it is considered that the film is slightly different in crystallinity because the substrate was heated at the time of preparation) was used and the incident angle α =
When 0.3 <α _c , the two-dimensional detector 5 (imaging plate) is installed in the direction including the extension of the surface of the sample 11 as shown in FIG. 1, and the surface optical system (I) and the surface optical system (I
The two pieces of information I) were measured simultaneously. FIG. 5 shows the measurement results. The iron oxide layer near the surface can be clearly confirmed, and the periodicity in the two-dimensional direction within the surface (in FIG. 5, <inside of the sample surface>
And the depth direction (in FIG. 5, <the depth direction from the surface>).
And display) are obtained. Measurement time 2
Minutes.

(Comparative Example 2) Using a sample similar to that of Example 2, measurement was performed by scanning a scintillation counter under the same measurement conditions. FIG. 6 shows the measurement results. here,
The scanning direction corresponds to the direction indicated by the broken line in FIG. 5 in the second embodiment. The diffraction peak from the iron oxide layer near the surface cannot be confirmed (the arrow in FIG. 6 indicates the position of the diffraction line predicted from the calculation). The measurement time was 35 hours. These Examples 1 and 2 and Comparative Examples 1 and 2
Are summarized in Table 2 below.

[0069]

[Table 2]

Example 3 A structural analysis apparatus shown in FIG. 1 was prepared. A rotating anti-cathode (Cu) device (output: 60 kV, 600 mA) was used as the X-ray source, and an imaging plate was used as the two-dimensional detector 5. The size of this structural analysis device is about 2 m in width × 1.5 m in depth × 1.5 m in height.

[0071]

According to the present invention, the periodicity in the two-dimensional direction and the information in the depth direction in the material surface can be simultaneously measured, and the three-dimensional (three-dimensional) information of the structure at the surface and the different depths near the surface can be measured. Is obtained. In addition, the measurement time can be significantly reduced. Furthermore, it is possible to detect an extremely weak signal by two-dimensional pattern analysis. Also,
As for the measurement involving a temporal change, a quantitative measurement is possible because the average value of the change during the measurement is equally observed at each measurement point.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of a structural analysis device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing another example of the structural analysis device according to the embodiment of the present invention.

FIG. 3 is a characteristic diagram showing measurement results of Example 1.

FIG. 4 is a characteristic diagram showing measurement results of Comparative Example 1.

FIG. 5 is a characteristic diagram showing measurement results of Example 2.

FIG. 6 is a characteristic diagram showing measurement results of Comparative Example 2.

FIG. 7 is a schematic diagram showing two optical systems for examining a material surface by an X-ray analysis method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sample holder 2-4 Angle control part 5 Two-dimensional detector 6 Control part 7 Arm 8 Curved rail 9 Scintillation detector 11 Sample 12 X-ray source

Claims (6)

[Claims] 1. A structure for irradiating a sample with X-rays and detecting the spatial distribution of energy and / or diffraction intensity of X-rays diffracted from the sample to analyze the structure of atoms and / or electrons of the sample. An analysis method, wherein an X-ray is incident within an angle α between an incident X-ray and a sample surface within a range of 0 ° <α ≦ 5 °, and the diffracted X-ray is detected by a two-dimensional detector. A structural analysis method characterized by the following. 2. When α _c is the critical angle of the sample with respect to the incident X-ray, the angle α between the incident X-ray and the sample surface is 0 ° <
2. The method according to claim 1, wherein the value is in a range of α ≦ 2α _c . 3. The method according to claim 1, wherein after measuring the diffraction line, the operation of moving the two-dimensional detector in an in-plane direction parallel to the surface of the sample and measuring again is repeated. Structural analysis method. 4. The method according to claim 2, wherein after measuring the diffraction line, the operation of moving the two-dimensional detector in an in-plane direction parallel to the surface of the sample and measuring again is repeated. Structural analysis method. 5. A method for analyzing the structure of atoms and / or electrons of a sample by irradiating the sample with X-rays and detecting a spatial distribution of energy and / or diffraction intensity of X-rays diffracted from the sample. Wherein the angle α formed between the incident X-ray and the sample surface can be made to enter the X-ray within a range of 0 ° <α ≦ 5 °, and the X-ray diffracted from the sample is A structural analysis device characterized by detecting with a two-dimensional detector. 6. When the x, y, z orthogonal coordinate system is set so that the surface of the sample is in the xy plane, the sample is rotated around the x, y axes, and x , A sample holder capable of moving in parallel in the directions of the axes y, z, a two-dimensional detector for detecting diffracted X-rays generated from the sample when the sample is irradiated with X-rays, a z-axis A first angle control unit for rotating the sample holder around the first angle control unit, and the two-dimensional detector is coupled to the first angle control unit. A second angle control unit disposed at the position of: the sample holder around the axis orthogonal to the z-axis;
And a third angle control unit for rotating the second angle control unit; and a control unit for controlling the two-dimensional detector and the first, second, and third angle control units. Characteristic structural analysis device.