JP2002139598A - X-ray monochromator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make switchable the face direction of reflection in a monochromator by rotating the monochromator around the axis of a tunnel-like through-hole formed in a columnar monocrystal block with the inner surface of the through-hole as a reflecting surface. SOLUTION: A monocrystal block of silicon is worked into an octagonal pole, and the through-hole 11 is formed in the center. The inner surface of the through-hole 11 is used as the reflecting surface of X-ray. The axis of the monochromator 10 is aligned to the direction <110> of the silicon monocrystal. Eight flat surfaces 14-28 constituting the side surfaces of the monochromator 10 aligned to any one of the directions <100>, <111>, <110> and <211> of the silicon monocrystal. The X-ray reflected twice by the inner surface of the through-hole 11 leaves through the back-side end surface 54 of the monochromator 10 or through slits 36, 38, 40 and 42 on the side surfaces. The face direction of reflection can be changed by changing the attitude of the monochromator 10 in placing on an L-shaped support table 12, and the incident angle of X-ray can be changed by ω-turn the monochromator 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray monochromator used for a high-resolution X-ray diffractometer.

[0002]

2. Description of the Related Art High-resolution X-ray diffractometers have been developed based on a measuring method called "two-crystal method". In the two-crystal method, when measuring a rocking curve of a sample of a single crystal (a graph showing the relationship between the intensity of a diffraction X-ray and the diffraction angle for a diffraction peak), the first crystal is used to diffract the X-ray to obtain a single color. After that, the sample (second crystal) is irradiated with this. Generally, a perfect crystal of silicon (Si) or germanium (Ge) is used as the first crystal. In this two-crystal method, as the first crystal, the same crystal as the sample crystal and the same lattice plane as the lattice plane to be measured (the same d value: lattice plane interval)
It is known that the use of a diffraction surface having the maximum diffraction angle gives the highest rocking curve angular resolution. Such an X-ray optical system in which the first crystal and the sample crystal have the same d value is called “parallel arrangement”. In such an ideal state, the half width of the obtained rocking curve becomes the narrowest, and the shape of the rocking curve at that time substantially matches the theoretically expected shape.

[0003] Alternatively, even if the first crystal and the sample crystal are not completely the same, a first crystal having a d value substantially equal to the lattice plane to be measured of the sample crystal may be used (this is called a pseudo-parallel arrangement). ), The resolution increases. For example, GaAs
In order to obtain a rocking curve of {400} reflection of a single crystal or InP single crystal, a {400} reflection of a Ge perfect crystal can be used as the first crystal.

[0004] When the difference between the d value of the first crystal and the d value of the second crystal increases, the effect due to wavelength dispersion is added in the form of convolution, and the resolution decreases. As a result, the half width of the obtained rocking curve also becomes wide. Therefore, when it is desired to measure the rocking curve with the highest resolution using the two-crystal method, the first crystal as close as possible to its d value depends on the type of the sample crystal and the plane index (reflection plane index) of the lattice plane to be measured. It is preferred to select Therefore, it is necessary to frequently exchange the first crystal according to the type of the sample crystal and the reflection surface index, and to perform the alignment of the X-ray optical system each time.

However, it is troublesome to rearrange the alignment by rearranging the crystal arrangement in the two-crystal method.
This is an operation that requires skill. Therefore, in order to facilitate this work, an optical system that can adjust the rotation of the second crystal around the first crystal or an optical system that can adjust the rotation of the X-ray source around the first crystal can be used. A system has been devised (for example, JP-A-1-86100). However, the work of exchanging crystals and the work of alignment are still necessary, and the work remains troublesome and cannot be said to be efficient.

The above-mentioned first crystal is usually a plate crystal, but it is also known to make it a channel cut monochromator. Channel cut monochromator
A groove is machined into a monolithic single-crystal block. By diffracting X-rays multiple times on the side of the groove,
A monochromatic and parallelized X-ray beam can be extracted (for example, JP-A-9-49999). When the light is diffracted an even number of times (for example, twice) by a channel cut monochromator, the incident X-ray beam is "parallel to"
A monochromatic and parallelized X-ray beam can be extracted. As described above, if the outgoing X-ray beam of the first crystal is parallel to the incident X-ray beam, the direction of the X-ray beam coming from the first crystal before and after the change is changed even when the first crystal is changed. Since they are parallel to each other, even if the first crystal is changed, the work of "rotating" the X-ray tube and the sample part (goniometer part) to perform alignment is not required (although the alignment by translation is necessary), The installation space of the device can be minimized.

An X-ray beam obtained by a channel cut monochromator is basically the same as an X-ray beam obtained by a single reflection plate crystal monochromator. However, if the X-ray beam is diffracted “multiple times” using a channel cut monochromator, the intensity of the bottom of the reflectance curve of the output X-ray beam can be extremely reduced, which is The effect is. Even when using a channel cut monochromator, it is necessary to replace the channel cut monochromator with the optimal d value according to the type of sample crystal and reflection surface index in order to measure the rocking curve with the highest resolution. is there. When the channel cut monochromator is exchanged, it is generally necessary to perform an operation of translating and aligning the sample section.

Further, a four-crystal monochromator that does not require translational movement of the sample portion is disclosed in, for example, Japanese Patent Application Laid-Open No.
108945, JP-A-4-264299). This four-crystal monochromator can be configured by combining two channel cut monochromators in mirror symmetry.
The X-ray beam obtained by the four-crystal monochromator has excellent monochromaticity and parallelism, and the incident X-ray beam and the output X-ray beam can be arranged on the same straight line. When a rocking curve of a sample is measured using an X-ray beam obtained by a four-crystal monochromator, a high resolution can always be obtained without depending on the type of the sample crystal or the reflection surface index. However, using this four-crystal monochromator has the disadvantage that the X-ray intensity is reduced by about two orders of magnitude compared to the two-crystal method. Therefore, when a four-crystal monochromator is used, (1) a powerful X-ray source is required, which makes the X-ray source expensive, and (2) a long measurement time is required to increase the intensity. There are problems. Therefore, as the reflecting surface of the monochromator, only a surface index capable of extracting an X-ray beam having a high intensity can be used.

Next, the current state of the evaluation method using a high-resolution X-ray diffractometer will be described. With the spread of thin-film technology, the measurement targets of high-resolution X-ray diffractometers have also expanded from conventional bulk crystals to thin-film crystals on substrates. The crystalline state of such a thin film can be classified into (1) a complete epitaxial layer (pseudomorphic layer), (2) an epitaxial layer in which a transition occurs at the interface between the substrate crystal and the epitaxial layer and strain is relaxed, and (3) an orientation distribution. (4) Strongly oriented polycrystalline thin films, (5) non-oriented polycrystalline thin films, and (6) amorphous thin films. Under such circumstances, the high-resolution X-ray diffractometer does not only perform the rocking curve measurement described above, but also the reflectance measurement (measurement of the reflectance in the vicinity of total reflection by low-angle incidence) and the like. In order to be applicable to the polycrystalline thin film diffraction measurement, a single device having various functions has been required.

Therefore, it has become necessary to prepare various incident optical systems for adjusting the parallelism and the wavelength range of X-rays to be irradiated on the sample according to the state of the sample. As a means for achieving this, a method of replacing a modularized incident optical unit or a method of switching an incident optical system without removing a crystal (for example, JP-A-9-49811) is employed. However, the method of replacing the modularized incident optical unit requires a variety of optical units, which increases the cost, and also makes fine tuning after the replacement troublesome.

In the method for switching the incident optical system disclosed in Japanese Patent Application Laid-Open No. 9-49811, for example, the following four types of incident optical systems can be selected. (1) Direct removal. That is, the X-ray beam is passed without being reflected by the crystal. This incident optical system can be mainly used for polycrystalline thin film diffraction. (2) Channel cut monochromator optical system. This incident optical system reflects X-rays twice using a channel cut crystal having Ge {220} as a reflection surface. Thereby, Cu
By cutting Kα2, only CuKα1 can be taken out. This incident optical system can be mainly used for reflectance measurement. (3) Four crystal monochromator high intensity mode. This incident optical system combines two channel cut crystals having Ge {220} as a reflection surface, and can be used, for example, for measuring a rocking curve of an epitaxial film. (4) 4-crystal monochromator high resolution mode. This incident optical system combines two channel-cut crystals each having Ge {440} as a reflection surface and has an extremely good resolution, so that it can be used, for example, for measuring a rocking curve of a complete epitaxial layer.

In order to switch between the four types of incident optical systems, it is only necessary to set the respective adjustment axes so that the registered values are set in advance by CPU control. Therefore,
The switching operation is easy. However, if an attempt is made to set another incident optical system, an optional crystal is required. In order to mount the optional crystal, the following operation is performed. First, the crystal attached to the incident optical system is removed together with the holding block by loosening the mechanical clamp. Then, the block holding the optional crystal is mechanically clamped. However, since the position and angle of the crystal when it is clamped vary depending on the strength of the clamping, the reproducibility is not always good. Therefore, it is necessary to readjust the optical system or at least fine-tune after setting to the previous adjustment value, which is troublesome.

The following can be considered as the above optional crystal. (1) An asymmetric reflection channel cut monochromator that compresses the beam width. This monochromator is used for increasing the intensity of the X-ray beam. That is, by using asymmetrical reflection such that the width of the output X-ray beam is smaller than the width of the incident X-ray beam, it is possible to increase the X-ray intensity per unit width of the output beam. However, the angular resolution is lower than that of symmetric reflection. This monochromator can be used to measure the X-ray reflectivity of a thin film. The X-ray reflectivity method is a method capable of evaluating the thickness and density of a thin film, and the density of a surface / interface. In order to apply this technique to very thin films and analyze with high accuracy, the change in the intensity of X-rays reflected from the thin film must be 10 degrees from the very small incident angle with a dynamic range of 8 digits or more. It is necessary to measure in the angular range up to about. For that purpose, a narrow high-intensity monochromatic X-ray beam is required, and for this purpose, an asymmetric reflection channel cut monochromator for compressing the beam width can be used.

(2) An asymmetric reflection channel cut monochromator for expanding the beam width. This monochromator uses asymmetric reflection such that the width of the output X-ray beam is larger than the width of the incident X-ray beam, contrary to the above-described beam width compression. The X-ray intensity per unit width of the output beam is reduced, but the angular resolution is improved. This monochromator can be used for X-ray topography, for example, and can increase the area that can be photographed at one time.

(3) A channel cut monochromator having a quasi-parallel arrangement. That is, the d value of the channel cut crystal is made substantially equal to the d value of the sample crystal. Using this monochromator, a rocking curve with high intensity and high resolution can be measured. Since the thickness of the epitaxial film tends to become thinner, the intensity of the diffracted X-rays from the epitaxial film may not be sufficiently obtained. In such a case, the monochromator can be used. Further, the present invention can also be used in the following cases where a four-crystal monochromator cannot cope at all due to insufficient strength. (A) When the crystal is warped, the X-ray irradiation width on the sample may be narrowed to avoid the influence, and in such a case, the intensity of the X-ray is reduced. (B) In the evaluation of the fine region of the selectively grown film, the X-ray irradiation field itself is set to the width,
It is necessary to focus the X-ray on the target area by narrowing down the height. At this time, since the cross section of the X-ray beam is narrowed down to about 20 μm in width and about 50 μm in height, the intensity of the X-ray is reduced. (C) In order to examine the state of an epitaxial thin film crystal, an evaluation method for examining one sample using two or more diffraction vectors has been established. For example, it is common to observe {400} symmetrical reflections, as well as to observe asymmetrical reflections using {511} reflections and {422} reflections, in order to investigate whether or not there is relaxation of distortion at the interface. Is being done.
In such an evaluation method, all reflections could be measured with high resolution by introducing a four-crystal monochromator, and the results were tentatively successful. However, when insufficient strength as described in (a) and (b) above becomes a problem, the four-crystal monochromator is insufficient and cannot be measured efficiently. Ultimately, in these cases where insufficient intensity is a problem, the "two-crystal method", which can take the intensity while maintaining good resolution, is an effective method, and it is quasi-parallel to the lattice plane of the sample crystal. A channel cut monochromator is used. However, replacement and alignment of the monochromator crystal are required.

[0016]

As described in detail above,
In a high-resolution X-ray diffractometer, the two-crystal method is suitable for ensuring sufficient "intensity" while maintaining good resolution. However, when the two-crystal method is adopted, in order to enable measurement under various conditions, it is necessary to replace the incident optical unit or switch the incident optical system, and the workability is poor.

An object of the present invention is to provide an X-ray monochromator capable of switching the plane orientation of the reflecting surface only by using one monochromator having a through hole.

[0018]

According to the X-ray monochromator of the present invention, a single crystal block is formed in a columnar shape, and a through hole is formed so as to penetrate in the axial direction. It is a reflection surface of a line beam. When such a monochromator is used, by rotating the monochromator about the axis of the through-hole, the plane direction in which the X-rays are reflected can be changed. Further, by rotating the monochromator about a rotation center line perpendicular to the axis of the through hole, the incident angle of X-rays to the monochromator can be changed.

In this monochromator, the outer shape can be a polygonal prism and the cross section of the through hole can be circular. When the outer shape is a polygonal prism, it is easy to set the rotational position of the monochromator around the axis of the through hole to a specific position by using the side surface of the polygonal prism. In a preferred embodiment, the profile is an octagonal prism. A cubic crystal can be used as the single crystal. In this case, the axial direction of the through-hole is <1 of the cubic crystal.
The normal directions of the eight planes constituting the side surfaces of the octagonal prism are set to <100><111><110> in accordance with the <10> direction.
There are four types of <211>.

The monochromator is preferably designed so that the X-ray beam is reflected twice on the inner surface of the through hole and then exits. However, the number of reflections is not limited to two, but may be another even number, for example, four or six times.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a method of expressing a plane index (Miller index) of a lattice plane of a crystal will be briefly described. Since the crystal structure of the silicon crystal used in this embodiment is cubic, there are six lattice planes equivalent to the (100) plane, for example. In general, these are represented by waveform brackets such as {100}. Similarly, in the [100] direction, six equivalent directions including the [100] direction are represented by angle brackets such as <100>. This specification also employs such a general expression method. Germanium crystal can be used instead of silicon crystal,
The same applies to germanium crystals because they are cubic.

FIG. 1 is a perspective view of an embodiment of the present invention. The X-ray monochromator 10 is made by processing a single crystal block of silicon. The monochromator 10 has an octagonal shape in appearance, and a through-hole 11 having a circular cross-section penetrating in the axial direction is formed at a center position of the octagonal cross-section. The inner surface of this through hole 11 is X
Used as a reflective surface for lines. Since the monochromator 10 uses the inner surface of the tunnel-shaped through-hole 11 as a reflection surface, it will be hereinafter referred to as a tunnel monochromator. This tunnel monochromator 10 has a support base 12 having an L-shaped cross section.
Used in combination with.

First, the outer shape of the tunnel monochromator 10 will be described. The sides of the tunnel monochromator 10 have eight planes 14, 16, 18, 20, 22, 24, 2
6 and 28, the cross section of the tunnel monochromator 10 is octagonal. FIG. 2 is a front view of the tunnel monochromator 10 and the support 12. The axial direction of the tunnel monochromator 10 (the direction perpendicular to the plane of FIG. 2) coincides with the <110> direction of the silicon single crystal. The directions of the eight planes that constitute the side surface of the tunnel monochromator 10 are as follows. First
The normal direction of the plane 14 (the upward plane in FIG. 2) coincides with the <100> direction of the silicon single crystal. The normal direction of the second plane 16 in the upper right direction is <11 of silicon single crystal.
1> direction. The normal direction of the third plane 18 facing right coincides with the <110> direction of the silicon single crystal. The normal direction of the lower right fourth plane 20 coincides with the <211> direction of the silicon single crystal. The downward fifth plane 22 is parallel to the upward first plane 14. The lower left-facing sixth plane 24 is parallel to the upper right-facing second plane 16.
The left-facing seventh plane 26 is parallel to the right-facing third plane 18. The eighth plane 28 facing the upper left is the fourth plane 2 facing the lower right.
Parallel to 0. In this way, four pairs of parallel planes are formed. These eight planes circumscribe a single virtual cylindrical surface 30. The through hole 11 is concentric with the cylindrical surface 30.

The normal direction <11 of the upper right second plane 16
1> forms an angle of 35.26 ° counterclockwise with respect to the normal direction <110> of the third plane 18 facing right. On the other hand, the normal direction <211> of the lower right fourth plane 20 is at an angle of 54.74 ° clockwise with respect to the normal direction <110> of the right third plane 18. Therefore,
These two normal directions <111> and <211> are orthogonal to each other. Therefore, the upper right facing second plane 16 and the lower right facing fourth plane 20 are orthogonal to each other. Further, the normal direction <100> of the upward first plane 14 and the rightward third plane 1
Since the normal directions <110> of 8 are orthogonal to each other, the first plane 14 and the third plane 18 are orthogonal to each other.

Next, the relationship between the L-shaped support base 12 and the tunnel monochromator 10 will be described. L-shaped support 12
Has a first reference plane 32 (which is horizontal in FIG. 2) and a second reference plane 34 which is perpendicular to this. After placing the downwardly facing fifth flat surface 22 of the tunnel monochromator 10 on the first reference surface 32 of the support 12, the tunnel monochromator 10 is pressed toward the second reference surface 34 of the support 12, and the tunnel The right-handed third plane 18 of the monochromator 10 comes into close contact with the second reference plane 34. Fifth plane 22 and third plane 1 of tunnel monochromator 10
Since the planes 8 are orthogonal to each other, these planes can be in close contact with the two reference planes 32, 34 (perpendicular to each other) of the support 12. The tunnel monochromator 10
It can be fixed to the support base 12 by lightly pressing it against the L-shaped support base 12 with an appropriate pressing spring. Incidentally, the tunnel monochromator 10 can take four kinds of postures with respect to the support base 12. That is, the first posture in which the fifth plane 22 is placed on the first reference surface 32 of the support base 12, the second posture in which the sixth plane 24 is placed, the third posture in which the fourth plane 20 is placed, and the third posture There are four types of fourth postures on which the plane 18 is placed. Switching between these four types of postures is equivalent to rotating the tunnel monochromator 10 by a predetermined angle φ around the rotation center line 76 (the axis of the through hole 11) shown in FIG. In other words, the outer shape of the tunnel monochromator is an octagonal prism in order to facilitate the operation of rotating the tunnel monochromator by φ so as to be at a predetermined angular position.

Next, the slit formed on the side surface of the tunnel monochromator 10 will be described. Slits 36, 38, 40, and 42 are formed in the four planes 22, 24, 26, and 28 of the tunnel monochromator 10, respectively.
In FIG. 2, these slits are indicated by broken lines. These slits are openings for X-rays reflected on the inner surface of the through-hole 11 to exit from the monochromator. 2, the first slit 36 extends from the inner surface of the through hole 11 to the fifth plane 22. The second slit 38,
The second slit 40 and the third slit 42 are respectively formed from the inner surface of the through hole 11 to the sixth plane 24, the seventh plane 26,
It penetrates to the plane 28. In FIG. 1, the second slit 38, the third slit 40, and the fourth slit 42 are visible. Each slit is open at the rear end surface in the axial direction of the tunnel monochromator 10. The axial length of each slit is not the same. This will be described later.

Next, the positional relationship between the tunnel monochromator 10 and the X-ray beam will be described. FIG. 3B is a front view showing the first posture of the tunnel monochromator 10. The first posture is a state in which the fifth plane 22 of the tunnel monochromator 10 is placed on the first reference plane 32 of the support base 12 and the third plane 18 is in contact with the second reference plane 34. FIG.
3A is a sectional view (horizontal sectional view) taken along line 3a-3a of FIG. In FIG. 3B, considering a virtual horizontal plane 44 at the height of the center position of the through hole 11 of the tunnel monochromator 10, the X-ray beam advances toward the tunnel monochromator 10 in the horizontal plane 44. Come. In FIG. 3A, the incident X-ray beam 46 is incident on a point P1 on the inner surface of the through hole 11. The tangent plane at P1 (the plane in contact with the inner surface of the through-hole) is the third plane 18
(Which is in contact with the second reference plane 34), and its normal direction is <110>. When the incident X-ray beam 46 composed of the characteristic X-ray CuKα1 ray is incident on the tangent plane at the point P1 at an incident angle θ, θ = 23.65 °
At this time, the diffraction condition for the {220} plane of the silicon single crystal is satisfied, and the X-rays are reflected on the inner surface of the through hole 11.
The X-ray reflected at the point P1 is similarly reflected at the point Q1 on the inner surface on the opposite side of the through-hole 11, and exits as an output X-ray beam 48. The emitted X-ray beam 48 exits from the end face 54 on the back side of the tunnel monochromator. Since the emitted X-ray beam 48 is an X-ray reflected on the {220} plane of the silicon single crystal, it is indicated as 220 in FIG.

In FIG. 3A, the incident angle θ is set to 53.
If it is 35 ° (this is the incident X-ray beam 50),
Satisfies another diffraction condition. In this case, the diffraction condition for the {440} plane of the silicon single crystal is satisfied. The X-ray reflected at the point P1 under the incident condition reaches the point R1 on the inner surface on the opposite side of the through-hole 11, and is also reflected at the point R1 and exits as the output X-ray beam 52. This outgoing X-ray beam 52 passes through the third slit 40 this time. If the third slit 40 is not formed, the outgoing X-ray beam 52 reflected twice will collide with the inner surface of the through-hole 11, but since the third slit 40 is formed,
You can go out without disturbing the monochromator.
The axial length L of the third slit 40 must be such that the emitted X-ray beam 52 does not hit the monochromator. The outgoing X-ray beam 52 is an X-ray reflected on the {440} plane of the silicon single crystal, and thus is indicated as 440 in FIG.

Next, the second posture of the tunnel monochromator will be described. FIG. 4B shows a tunnel monochromator 10.
It is a front view which shows the 2nd attitude | position of. In the second posture, the sixth plane 24 of the tunnel monochromator 10 is placed on the first reference plane 32 of the support base 12 and the fourth plane 20 is moved to the second reference plane 3.
4. FIG. 4A is a sectional view taken along line 4a-4a in FIG. 4B. The incident X-ray beam 56 is incident on a point P2 on the inner surface of the through hole 11. The tangent plane at point P2 is the fourth plane 20 (contacting the second reference plane 34)
And its normal direction is <211>. The incident X-ray beam 56 composed of the characteristic X-ray CuKα1
When incident at an incident angle θ with respect to the tangential plane at the point, when θ = 44.02 °, the ｛42
X-rays are reflected, satisfying the diffraction condition for the 2｝ plane. The X-ray reflected at the point P2 is also reflected at the point Q2 on the inner surface on the opposite side of the through-hole 11, and exits as an output X-ray beam 58. The emitted X-ray beam 58 passes through the fourth slit 42. The axial length of the fourth slit 42 needs to be such that the emitted X-ray beam 58 does not hit the monochromator. Of course, the required length of the third slit 40 (FIG. 3A) and the fourth slit 42
The required length is different. Since the output X-ray beam 58 is an X-ray reflected on the {422} plane of the silicon single crystal, FIG.
Is displayed as 422. The above-mentioned point P2 is in the same position as the point P1 in the state of FIG. However, the position on the inner surface of the through hole 11 of the tunnel monochromator 10 is another position.

Next, the third position of the tunnel monochromator will be described. FIG. 5B shows a tunnel monochromator 10.
It is a front view showing the 3rd posture of. In the third position, the fourth plane 20 of the tunnel monochromator 10 is placed on the first reference plane 32 of the support base 12 and the second plane 16 is moved to the second reference plane 3.
4. FIG. 5A is a sectional view taken along line 5a-5a in FIG. 5B. The incident X-ray beam 60 is incident on a point P3 on the inner surface of the through hole 11. The tangent plane at point P3 is the second plane 16 (contacting the second reference plane 34).
And its normal direction is <111>. The incident X-ray beam 60 composed of the characteristic X-ray CuKα1 ray is
When incident at an incident angle θ with respect to the tangent plane at the point, X-rays are reflected at θ = 14.22 °, satisfying the diffraction condition for the {111} plane of the silicon single crystal. P3
The X-ray reflected by the point is Q3 on the inner surface on the opposite side of the through hole 11.
The light is similarly reflected at the point, and exits as an outgoing X-ray 62 beam. This emitted X-ray beam 62 exits from the end face 54 on the back side of the tunnel monochromator. Since the emitted X-ray beam 62 is an X-ray reflected on the {111} plane of the silicon single crystal, it is indicated as 111 in FIG.

In FIG. 5A, the incident angle θ is set to 47.
When the angle is set to 48 ° (this is defined as an incident X-ray beam 64),
Satisfies another diffraction condition. In this case, the diffraction condition for the {333} plane of the silicon single crystal is satisfied. The X-ray reflected at the point P3 under the incident conditions reaches the point R3 on the inner surface on the opposite side of the through hole 11, and is also reflected at the point R3 and exits as an output X-ray beam 66. The emitted X-ray beam 66 passes through the second slit 38. The length of the second slit 38 must be such that the emitted X-ray beam 66 does not hit the monochromator. The outgoing X-ray beam 66 is an X-ray reflected on the {333} plane of the silicon single crystal, and thus is indicated as 333 in FIG.

Next, the fourth position of the tunnel monochromator will be described. FIG. 6B shows a tunnel monochromator 10.
It is a front view showing the 4th posture of. In the fourth posture, the third plane 18 of the tunnel monochromator 10 is placed on the first reference plane 32 of the support base 12 and the first plane 14 is moved to the second reference plane 3.
4. FIG. 6A is a sectional view taken along line 6a-6a in FIG. 6B. The incident X-ray beam 68 is incident on a point P4 on the inner surface of the through hole 11. The tangent plane at point P4 is the first plane 14 (contacting the second reference plane 34)
And its normal direction is <100>. The incident X-ray beam 68 composed of the characteristic X-ray CuKα1
When incident at an incident angle θ with respect to the tangent plane at the point, when θ = 34.57 °, the ｛40
X-rays are reflected, satisfying the diffraction condition on the 0 ° plane.
The X-ray reflected at the point P4 is similarly reflected at the point Q4 on the inner surface on the opposite side of the through-hole 11, and exits as an output X-ray beam 70. The emitted X-ray beam 70 is
Pass through. The length of the first slit 36 needs to be such that the emitted X-ray beam 70 does not hit the monochromator. Since the emitted X-ray beam 70 is an X-ray reflected on the {400} plane of the silicon single crystal, FIG.
In FIG. 4A, 400 is displayed.

FIG. 12 shows a list of the four types of postures described above and possible reflection surface indices in each posture. There are a total of six possible reflection surface indices, and this tunnel monochromator can switch out six types of X-rays to be extracted.

Next, a method of arranging the tunnel monochromator between the X-ray source of the X-ray diffractometer and the sample will be described. In FIG. 1, the support base 12 is mounted on a turntable (not shown) that can rotate around a rotation center line 72. The rotation about the rotation center line 72 will be referred to as ω rotation.
This ω rotation is equivalent to X with respect to tunnel monochromator 10.
This is for adjusting the incident angle of the line beam. The rotation center line 72 is in contact with the inner surface of the through hole 11 of the tunnel monochromator 10, as shown in FIG. The position where the rotation center line 72 and the inner surface of the through hole 11 are in contact with each other is a point P1. When the rotation center line 72 is in contact with the inner surface of the through hole 11, there is an advantage that the X-ray irradiation position on the inner surface of the through hole 11 does not change when the tunnel monochromator 10 is rotated by ω. However, the rotation center line 72 is
It is also possible to set at a position not in contact with the inner surface of the through hole 11.

In order to satisfy a predetermined diffraction condition by moving the tunnel monochromator with the X-ray source fixed, the following is performed. In FIG. 7A, the support 12
When the support 12 is rotated by ω around the rotation center line 72 while the tunnel monochromator 10 is placed in the first posture on the above, the tunnel monochromator 10 can be tilted with respect to the incident X-ray beam 74. it can. If the tunnel monochromator 10 is rotated by ω so that the incident X-ray beam 74 is incident on the inner surface of the through hole 11 at an incident angle of 23.65 °, the state becomes the same as the state of {220} reflection in FIG. .

FIG. 7B shows a case where the tunnel monochromator 10 in the first position is rotated by ω around the rotation center line 72 so that the incident angle is 53.35 °. Figure 3
This is the same state as the {440} reflection.

FIG. 8 shows the tunnel monochromator 10 in the second position rotated by ω around the rotation center line 72 so that the incident angle is 44.02 °. This makes $ 4 in Fig. 4
It is in the same state as 22 ° reflection.

FIG. 9A shows a state in which the incident angle is set to 14.22 ° by rotating the tunnel monochromator 10 in the third position by ω around the rotation center line 72. Figure 5
The state is the same as the {111} reflection.

FIG. 9B shows the tunnel monochromator 10 in the third position rotated by ω around the rotation center line 72 to set the incident angle to 47.48 °. Figure 5
In the same state as the {333} reflection.

FIG. 10 shows the tunnel monochromator 10 in the fourth position rotated by ω around the rotation center line 72 so that the incident angle is 34.57 °. This results in the same state as the {400} reflection in FIG.

FIG. 11 is a standard stereographic projection centered on the cubic (110) pole. A set of three numbers shown in this stereo projection represents a plane index (Miller index) of a lattice plane of the crystal. The surface index on the circumference is a surface index that can obtain Bragg reflection among surface indices having a plane orientation perpendicular to the <100> direction. The six types of surface indices shown in FIG. 12 are all surface indices on the circumference (or an integer multiple of the surface indices). In the surface index, a horizontal line is usually put on the numeral in the case of the back to distinguish the front and back of the lattice surface, but in this drawing, a minus sign is attached before the numeral.

Next, applications of the six types of X-rays reflected on each reflecting surface will be described. Since the intensity of the X-ray beam (FIG. 7A) obtained by {220} reflection is relatively large, the reflectivity is measured (X-rays are incident on the sample surface, and the reflectivity near total reflection is reduced). Measurement). Also,
The {220} reflection can be used as a four-crystal monochromator by arranging two tunnel monochromators in mirror symmetry, and in that case, is suitable for measuring a rocking curve.

The X-ray beam (FIG. 7B) obtained by the {440} reflection has a smaller intensity than the {220} reflection but has a higher resolution, and is also used as a four-crystal monochromator to produce a rocking curve. Suitable for measuring

The X-ray beam obtained by {400} reflection (FIG. 10) is suitable for measuring a rocking curve by using a quasi-parallel arrangement. That is, when measuring the rocking curve of the {400} plane of GaAs (or the epitaxial film grown thereon), by using the X-ray diffracted on the {400} plane of the silicon crystal,
A quasi-parallel arrangement situation of the two crystal method can be created. The d value of the {400} plane of the silicon crystal is close to the d value of the {400} plane of the GaAs to be measured.

The X-ray beam (FIG. 8) obtained by the {422} reflection is suitable for measuring a rocking curve by using it in a quasi-parallel arrangement. That is, when measuring the rocking curve of the asymmetric reflection {422} plane of GaAs (or the epitaxial film grown thereon), the X-ray diffracted by the {422} plane of the silicon crystal is used to measure the bicrystal. A quasi-parallel arrangement situation of the modulus can be created.

The X-ray beam obtained by the {111} reflection (FIG. 9A) has a relatively high intensity and is suitable for reflectance measurement.

The X-ray beam obtained by the {333} reflection (FIG. 9B) is suitable for measuring a rocking curve by using it as a quasi-parallel arrangement with respect to the {511} reflection of the sample crystal. The surface spacing (d value) of the {333} surface is {5}
Since it is the same as the plane spacing of the 11 ° plane, for example, GaAs
When measuring the rocking curve of the asymmetrical reflection {511} plane (or the epitaxial film grown thereon), the X-ray diffracted on the {333} plane of the silicon crystal is used to measure A parallel arrangement situation can be created.

Next, the dimensions of the tunnel monochromator of the embodiment will be described. In FIG. 2, the diameter of the virtual cylindrical surface 30 is 10 mm to several tens mm. Through hole 1
The inner diameter of 1 is one third to one half of the diameter of the cylindrical surface 30.
It is. Axial direction (longitudinal direction) of tunnel monochromator
Is determined by the relationship between the inner diameter of the through hole 11 and the Bragg angle of reflection. Of the above six types of reflection, the one with the lowest Bragg angle is {111} reflection, and CuKα1
The incident angle is 14.22 ° with respect to the X-ray wavelength (FIG. 9A). The required length of the tunnel monochromator is determined by this lowest angle reflection. In this case, the through hole 1
Assuming that the inner diameter of 1 is 5 mm, the minimum distance (longitudinal distance between two reflection points) required for two reflections on the inner surface of the through hole is about 20 mm. In the actual design, X
Since there is a margin of about several mm at the entrance and exit of the line,
The required length of the tunnel monochromator is about 30 mm.

In FIG. 2, the cross-sectional shape of the inner surface of the through hole 11 is not circular but may be octagonal. That is, each side of the octagon on the inner surface of the through hole 11 may be parallel to each side of the octagon on the outer surface.

In the above-described embodiment, by combining an octagonal column monochromator with an L-shaped support,
Although four types of postures can be easily set, the tunnel monochromator can be freely rotated around the axis, and
If a rotation mechanism capable of stopping at an arbitrary rotation angle is provided (in that case, it is not necessary to use an octagonal prism), more reflections than the above-described six types of reflections can be extracted. In the case of the tunnel monochromator cut out in the azimuth as shown in FIG. 2, in principle, it is possible to extract reflections at all surface indices located on the circumference of the stereoscopic projection view of FIG. In this case, in addition to the six types of reflections shown in FIG. 12 described above, {311 {331 {511} reflections are possible. Although asymmetric reflection occurs, {531} reflection is also possible.

[0051]

According to the X-ray monochromator of the present invention, a tunnel-shaped through-hole is formed in one single crystal block.
Since the inner surface of the through hole is a reflecting surface, the plane orientation of the reflecting surface can be switched by rotating the monochromator about the axis of the through hole. Therefore, X-rays reflected at various surface indices can be extracted.

[Brief description of the drawings]

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

FIG. 2 is a front view of a tunnel monochromator and a support base.

FIG. 3 is a plan sectional view and a front view showing a positional relationship between a tunnel monochromator in a first posture and an X-ray beam.

FIG. 4 is a plan sectional view and a front view showing a positional relationship between a tunnel monochromator in a second posture and an X-ray beam.

FIG. 5 is a plan sectional view and a front view showing a positional relationship between a tunnel monochromator in a third posture and an X-ray beam.

FIG. 6 is a plan sectional view and a front view showing a positional relationship between a tunnel monochromator in a fourth position and an X-ray beam.

FIG. 7 is a horizontal sectional view showing two setting states of the tunnel monochromator in the first posture when the direction of the incident X-ray is fixed.

FIG. 8 is a horizontal sectional view showing a setting state of the tunnel monochromator in the second posture when the direction of incident X-rays is fixed.

FIG. 9 is a horizontal cross-sectional view showing two setting states of the tunnel monochromator in the third posture when the direction of incident X-rays is fixed.

FIG. 10 is a horizontal sectional view showing a setting state of a tunnel monochromator in a fourth posture when the direction of incident X-rays is fixed.

FIG. 11 is a standard stereo projection view of a (110) plane of a cubic crystal.

FIG. 12 is a table showing six possible surface indices of reflection.

[Explanation of symbols]

 Reference Signs List 10 tunnel monochromator 11 through hole 12 support base 14 first plane 16 second plane 18 third plane 20 fourth plane 22 fifth plane 24 sixth plane 26 seventh plane 28 eighth plane 30 cylindrical plane 32 first reference plane 34 Second reference plane 36 First slit 38 Second slit 40 Third slit 42 Fourth slit 72 Rotation centerline of ω rotation 76 Rotation centerline of φ rotation

Claims (6)

[Claims] 1. An X-ray monochromator in which a single-crystal block is formed in a columnar shape, a through-hole is formed so as to penetrate in the axial direction, and an inner surface of the through-hole is a reflection surface of an X-ray beam. 2. A single-crystal block having a polygonal column shape and a through-hole having a circular cross-section so as to penetrate the block in the axial direction. An X-ray beam is reflected an even number of times on the inner surface of the through-hole. X-ray monochromator. 3. The X-ray monochromator according to claim 1, wherein the single crystal is a cubic crystal, and an axial direction of the through hole coincides with a <110> direction of the cubic crystal. Characteristic X-ray monochromator. 4. The X-ray monochromator according to claim 2, wherein the polygonal prism is an octagonal prism, and side surfaces of the octagonal prism are formed of eight planes from a first plane to an eighth plane. The plane and the fifth plane are parallel to each other, and the second plane and the sixth plane are parallel to each other.
The planes are parallel to each other, the third plane and the seventh plane are parallel to each other, the fourth plane and the eighth plane are parallel to each other,
The first plane and the third plane are perpendicular to each other, the second plane and the fourth plane are perpendicular to each other, and the eight planes circumscribe the same virtual cylindrical surface. Line monochromator. 5. The X-ray monochromator according to claim 4, wherein the single crystal is a cubic crystal, an axial direction of the through-hole coincides with a <110> direction of the cubic crystal, and The normal direction of the plane and the fifth plane is <10
0> direction, the normal direction of the second plane and the sixth plane coincides with the <111> direction of the cubic crystal,
The normal direction of the first plane and the fifth plane is <1 of the cubic crystal.
An X-ray monochromator, wherein the X-ray monochromator coincides with the <10> direction, and the normal direction of the first plane and the fifth plane coincides with the <211> direction of the cubic crystal. 6. The X-ray monochromator according to claim 1, wherein the X-ray beam reflected by the inner surface of the through hole exits on a side surface of the columnar block. X characterized by having an opening formed
Line monochromator.