JP2002168997A - X-ray micro-beam generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate an X-ray micro-beam of a sufficiently small diameter and small diffusion angle using asymmetric reflection crystals. SOLUTION: Asymmetric reflection crystals 18a and 18b are disposed to be capable of contracting the diameter and diffusion angle of an incidental X-ray beam in a horizontal direction, and asymmetric reflection crystals 18c and 18d are disposed to be capable of contracting the diameter and diffusion angle of the X-ray beam in a vertical direction. The asymmetric reflection crystals 18a and 18b (18c and 18d) are supported to be capable of simultaneously rotating around a first support shaft 42, and the asymmetric reflection crystal 18b (18d) is supported to be capable of solely rotating around a second support shaft 43.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray microbeam generating apparatus for generating an X-ray microbeam by using an asymmetric reflection crystal.

[0002]

2. Description of the Related Art In recent years, when miniaturizing a semiconductor device, it has become necessary to analyze a localized stress acting on a specific region of the semiconductor device (for example, a region immediately below a gate electrode of a MOS transistor) with high accuracy. I have. In order to perform such an analysis, it is necessary to use a highly parallel X
It is considered optimal to perform X-ray diffraction using a X-ray microbeam as a probe. For this reason, research for generating an X-ray microbeam having a small diameter (about several micrometers) and a small divergence angle (about 10 ^-5 radians) in accordance with miniaturization of a semiconductor element has been advanced.

[0003]

As a technique for generating an X-ray microbeam, a technique using a curved multilayer mirror or a Fresnel zone plate is known. According to these techniques, although the beam diameter can be reduced to some extent, a highly parallel beam having a sufficiently small divergence angle cannot be obtained. Therefore, it is practically impossible to use the X-ray microbeam generating apparatus obtained by the above technique to analyze localized stress or the like acting on a specific region of a semiconductor element with high accuracy. It is also conceivable to generate an X-ray microbeam having a small diameter and a small divergence angle by using an asymmetric reflective crystal having a surface that is not parallel to the crystal lattice plane. However, a specific configuration for that purpose is not yet known.

Accordingly, an object of the present invention is to provide an X-ray microbeam generator capable of generating an X-ray microbeam having a sufficiently small diameter and a small divergence angle by using an asymmetric reflection crystal. .

[0005]

In order to achieve the above object, an X-ray microbeam generating apparatus according to claim 1 generates an X-ray microbeam using an asymmetric reflective crystal having a surface that is not parallel to a crystal lattice plane. An X-ray micro-beam generating apparatus for performing the above-described operation, comprising a first crystal support member and a second crystal support member. The first crystal support member includes:
The beam width of the X-rays reflected by the first asymmetrical reflection crystal and the second asymmetrical reflection crystal on which the X-ray diffracted by the first asymmetric reflection crystal is incident is reduced in the first direction. Thus, it is possible to adjust the surface angles of the supported first and second asymmetric reflection crystals, respectively. Further, the second crystal support member has a third asymmetric reflection crystal on which the diffracted X-rays by the second asymmetrical reflection crystal are incident, and a fourth asymmetrical reflection crystal on which the diffracted X-rays by the third asymmetric reflection crystal is incident. While supporting the asymmetrical reflection crystal of the third type such that the beam width of the X-rays reflected by them is reduced in a second direction substantially perpendicular to the first direction. It is possible to adjust the surface angle of each of the four asymmetric reflection crystals.

According to the first aspect, the first and second asymmetric reflection crystals are supported by the first crystal support member such that the surface angles thereof can be adjusted, so that the first and second asymmetric reflection crystals are provided. It is possible to place the crystals sufficiently close together. Thereby, before the beam reduced in the first direction by the first asymmetric reflection crystal is expanded, the beam is reduced again in the first direction by the second asymmetric reflection crystal. An X-ray micro-beam having a sufficiently small diameter (for example, in the horizontal direction) and a small divergence angle is generated. Similarly, the third and fourth asymmetric reflective crystals are supported by the second crystal support member so that the surface angles thereof can be adjusted, so that the third and fourth asymmetric reflective crystals are sufficiently close to each other. It becomes possible to arrange. Thereby, before the beam reduced in the second direction by the third asymmetric reflective crystal is expanded, the beam is reduced again in the second direction by the fourth asymmetric reflective crystal. An X-ray microbeam having a sufficiently small diameter (for example, in the vertical direction) and a small divergence angle is generated. This makes it possible to generate an X-ray microbeam having a sufficiently small diameter and a small divergence angle in any of two substantially orthogonal directions.

Further, in the X-ray microbeam generating apparatus according to the present invention, the first crystal support member rotates the first and second asymmetrical reflection crystals about the same axis to thereby adjust the surface angle of the first and second asymmetric reflection crystals. And a second adjustment mechanism for adjusting the surface angle of only one of the first and second asymmetrical reflection crystals, wherein the second crystal support member is provided. Is the third and fourth
A third adjusting mechanism that simultaneously adjusts the surface angle by rotating the asymmetrical reflection crystal around the same axis;
A fourth adjustment mechanism for adjusting the surface angle of only one of the third and fourth asymmetrical reflection crystals.

According to the second aspect, since the two asymmetric reflective crystals are respectively rotated around the same axis by the first or third adjusting mechanism, the relative positions of the two asymmetric reflective crystals with respect to the incident X-rays. It is possible to change the relationship with great freedom. Therefore, when an X-ray microbeam is generated using X-ray diffraction using synchrotron radiation having a continuous energy value as a light source, the energy of incident X-rays near the surface is determined according to the measurement depth of the sample. It can be changed with great freedom to adapt to any Bragg diffraction conditions. Further, since the second and fourth adjusting mechanisms adjust the surface angle of only one of the two asymmetrical reflection crystals, the first or third adjusting mechanism adjusts the surface angle.
It is possible to compensate for the angular deviation from the incident angle required to cause diffraction in the second and fourth asymmetrical reflective crystals caused by the rotation of the two asymmetrical reflective crystals about the same axis. .

Further, in the X-ray micro beam generating apparatus according to a third aspect, the second adjusting mechanism and the fourth adjusting mechanism each have a solid actuator for adjusting a surface angle of the asymmetric reflection crystal. It is characterized by having.

According to the third aspect, the surface angle of the asymmetrical reflection crystal can be adjusted by the solid-state actuator.
And the fourth adjustment mechanism can be small and have a simple configuration. This makes it possible to arrange the first and second asymmetrical reflection crystals and the third and fourth asymmetrical reflection crystals sufficiently close to each other. As the solid actuator, for example, an actuator having a piezo element, a magnetostrictive element, or the like can be used.

In the X-ray microbeam generating apparatus according to a fourth aspect of the present invention, the supporting axes of the first and second asymmetric reflecting crystals and the supporting axes of the third and fourth asymmetric reflecting crystals are orthogonal to each other. In addition, the first crystal support member and the second crystal support member are arranged.

According to the fourth aspect, since both support shafts are perpendicular to each other, the first crystal support member and the second crystal support member hardly interfere with each other, and both support shafts are not interfered with each other. Can be brought closer to each other.
This makes it possible to arrange the second asymmetric reflection crystal and the third asymmetric reflection crystal sufficiently close to each other,
An X-ray microbeam having a smaller diameter and a smaller divergence angle can be generated.

The X-ray microbeam generating apparatus of the present invention is not limited to the first to fourth asymmetric reflection crystals, and may use five or more asymmetric reflection crystals.
In that case, the first and second asymmetric reflection crystals (or the third crystal support) may be provided on the first crystal support (or the second crystal support).
And a fourth asymmetric reflection crystal), or another asymmetric reflection crystal may be supported, or a separately provided crystal support member may have another asymmetric reflection crystal different from the first to fourth asymmetric reflection crystals. Crystals may be supported. However, the direction of the incident X-ray beam and the direction of the reflected X-ray beam are made substantially the same by using a multiple of two asymmetrical reflection crystals that reduce the beam in each of two directions substantially orthogonal to each other. It becomes easier. On the other hand, considering that the intensity of diffracted X-rays decreases as the number of asymmetric reflection crystals used increases, the number of asymmetric reflection crystals for reducing the beam in each of two orthogonal directions is about four. Is realistic.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the principle of asymmetrical reflection of X-rays according to the present invention will be described with reference to FIG. As shown in FIG. 1, the silicon single crystal 1 is an asymmetric crystal,
The surface 1a and the crystal lattice plane 1b are not parallel but form an angle α. Therefore, the incident X-ray beam 2 is
Instead of being reflected so as to be symmetrical about an axis perpendicular to the crystal lattice plane 1b, it is reflected so as to be symmetrical about an axis perpendicular to the crystal lattice plane 1b.
That is, when the angle of incident X-ray beam 2 makes with the crystal lattice plane 1b and theta _B, the angle of diffracted X-ray beam 3 reflected by the crystal lattice plane 1b forms a crystal lattice plane 1b also becomes theta _B. On the other hand, the angle between the incident X-ray beam 2 and the surface 1a of the silicon single crystal 1 is θ _B + α, and the angle between the diffracted X-ray beam 3 and the surface 1a of the silicon single crystal 1 is θ _B −α.

The beam width of the incident X-ray beam 2 is set to L _0.
Then, the beam width L _h of the diffracted X-ray beam 3 is b × L ₀
Is equal to Where b is an asymmetry factor and si
n (θ _B -α) / sin (θ _B + α). Since the asymmetry factor b has a value of 1 or less, the beam width L _h of the diffracted X-ray beam 3 is smaller than the beam width L ₀ of the incident X-ray beam 2. Regarding the divergence angle, the diffraction X-ray beam 3
Becomes larger than the incident X-ray beam 2. Since the divergence angle is about Δb times the divergence angle of the diffracted X-rays from the symmetrical reflection crystal, it is possible to avoid an extremely large divergence angle.
As described above, by reflecting X-rays using an asymmetric crystal, a diffracted X-ray beam having a small diameter and a small divergence angle can be obtained.

Next, a preferred embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a schematic configuration diagram of an optical system of the X-ray analysis apparatus including the X-ray microbeam generation unit according to the present embodiment. As shown in FIG. 2, the synchrotron radiation 11 provided to the X-ray analyzer 10 is incident on a spectroscope 12 having two symmetric reflection crystals 12a and 12b, both of which are silicon single crystals. The X-ray beam 13 taken out of the spectroscope 12 passes through the slits 15 and then is made of four asymmetric reflection crystals 18a, 18b and 18 both of which are silicon single crystals.
c, 18d are supplied to the X-ray microbeam generation unit 16.

Of the four asymmetrical reflection crystals 18a to 18d, the asymmetrical reflection crystals 18a and 18b can reduce the diameter and divergence angle of the incident X-ray beam 13 in the horizontal direction based on the above-described principle. And the asymmetric reflection crystals 18c and 18d
It is arranged so that the diameter and the divergence angle of the line beam 13 can be reduced in the vertical direction. for that reason,
X-ray beam 1 that has passed through X-ray micro-beam generation unit 16
Reference numeral 3 denotes a microbeam whose diameter and divergence angle are reduced in two directions, horizontal and vertical.

The X-ray beam 19 whose diameter and divergence angle have been reduced by the X-ray microbeam generator 16 is incident on a sample 20 to be analyzed. The portion of the surface of the sample 20 irradiated with the X-ray beam 19 is composed of two CCD cameras 21.
a, 21b. The X-ray beam 22 diffracted by the sample 20 enters the scintillation counter 24 via the analyzer 23.

Next, the detailed structure of the X-ray micro-beam generator 16 included in the X-ray analyzer 10 shown in FIG. 2 will be described with reference to FIGS. FIG.
FIG. 3 is a perspective view of a support mechanism of an asymmetric reflection crystal mounted on the X-ray analysis apparatus shown in FIG. FIG. 4 is a side view of a crystal holder included in the support mechanism of the asymmetric reflection crystal. FIG.
FIG. 5 is a plan view of the crystal holder shown in FIG. FIG. 6 is an enlarged view of the vicinity of the tip of the piezo element in the crystal holder shown in FIG. FIG. 7 is a schematic diagram of a main part of the support mechanism depicted in FIG.

The X-ray microbeam generator 16 shown in FIG. 2 includes a support mechanism 30 for an asymmetrical reflection crystal as shown in FIG. The support mechanism 30 includes a substantially L-shaped main body 31, a crystal holder 33 attached to a mounting portion 32 a provided on an inner side surface 31 a of the main body 31 so as to project in the horizontal direction, and a lower upper surface 31 b of the main body 31. And a crystal holder 34 attached to the attached attachment portion 32b so as to protrude upward.

In the main body 31, levers (not shown) interlocking with the mounting portions 32a, 32b are provided with crystal holders 33, 34.
Are provided so as to extend in the radial direction. These levers have a crystal holder 3 near their outer ends.
A micro head (a member whose length in the rotation axis direction changes according to the rotation angle: not shown) is arranged on the opposite side of the spring from the springs 3 and 34. I have. The amount of rotation of the microhead is controlled by a motor (not shown) coupled to the microhead via a plurality of gears. That is, it is possible to control the rotation position of the lever by changing the length of the micro head by controlling the motor, whereby the rotation angle of the mounting portions 32a and 32b can be reduced by the minimum rotation angle unit of the motor and a plurality of The angle can be adjusted to a desired angle in units of a minute angle corresponding to the gear down ratio of the gear.

As shown in FIGS. 4 and 5, the crystal holder 33 (hereinafter, the crystal holder 33 will be described. Since the crystal holder 34 is configured substantially in the same manner as the crystal holder 33, Is omitted) is a substantially cylindrical base 41 that fits with the mounting portion 32a.
And a first support shaft 42 on the rotation axis of the mounting portion 32a.
And a second support shaft 43 supported on the side by the first support shaft 42. The tops of the first support shaft 42 and the second support shaft 43 are provided with the asymmetrical reflection crystal 18.
a, a crystal stage 42a on which 18b is installed,
43a are provided respectively. In the vicinity of the center of the second support shaft 43 in the longitudinal direction, a concave portion 43c having a depth up to the center of the second support shaft 43 is provided. Also, the first support shaft 42
And second support shaft 43 includes crystal stages 42a, 43
The positions of the crystals placed on the screw heads 42b, 43
It is divided into a plurality of parts so that the angle can be manually adjusted by rotating b.

As described above, the mounting portion 32b is attached to the main body 31.
Since the first support shaft 42 can rotate in accordance with the rotation of the internal motor, the first support shaft 42 rotates around the rotation of the mounting portion 32b. Also, the second support shaft 42 supported by the first support shaft 42
The support shaft 43 rotates around the rotation of the first support shaft 42. That is, the first support shaft 42 and the second support shaft 43 simultaneously rotate around the central axis of the first support shaft 42 with the rotation of the mounting portion 32b.

The crystal holder 33 is perpendicular to the center axis of the first support shaft 42 so as to penetrate the first support shaft 42 and contact the tip with the second support shaft 43 in the concave portion 43c. Actuator 4 whose direction is the displacement direction
5 are supported. As shown in FIG. 6, the piezo actuator 45 has a hemispherical tip portion 45a,
The distal end portion 45a is in contact with the second support shaft 43 at a position 43e which is separated from the shaft center 43d of the second support shaft 43 by a distance d. Therefore, when an electric signal is applied to the piezo actuator 45 and its length changes, the second support shaft 43 rotates about the shaft center 43d, and the rotational displacement angle is proportional to the amount of change in the length of the piezo actuator 45. It will be.

As described above, in the present embodiment, the two asymmetric reflection crystals 18a and 18b are supported by one crystal holder 33 so that the surface angles can be adjusted, respectively.
The two asymmetric reflection crystals 18a and 18b can be arranged sufficiently close to each other. Therefore, before the beam reduced in the horizontal direction by the asymmetrical reflection crystal 18a is expanded again in the horizontal direction by the asymmetrical reflection crystal 18b, the X-ray having a sufficiently small diameter and small divergence angle in the horizontal direction is obtained. A microbeam is generated. Although not described in detail here, the crystal holder 34 generates an X-ray microbeam having a sufficiently small diameter and a small divergence angle in the vertical direction, similarly to the crystal holder 33.
Therefore, the X-ray microbeam generation unit 1 of the present embodiment
6 makes it possible to generate an X-ray microbeam having a sufficiently small diameter and a small divergence angle in both the horizontal and vertical directions.

In the present embodiment, the crystal holder 33 attached to the main body 31 of the support mechanism 30 included in the X-ray microbeam generator 16 is supported by the first and second support shafts 42 and 43, respectively. A mechanism for simultaneously adjusting the surface angles of the asymmetrical reflection crystals 18a, 18b by rotating the two asymmetrical reflection crystals 18a, 18b around the first support shaft 42, and a piezo actuator 45
And a mechanism for adjusting the surface angle of only the asymmetric reflection crystal 18b provided on the second support shaft 43.

Thus, in the present embodiment, when the two asymmetric reflection crystals 18a and 18b are rotated around the first support shaft 42, the two asymmetric reflection crystals with respect to the incident X-ray beam 13 The relative positional relationship between 18a and 18b can be changed with a large degree of freedom. Therefore, determination is made based on Bragg's diffraction equation (2 dsin θ _B = nλ: d = distance between lattice planes, θ _B = angle of incidence of the X-ray beam on the lattice plane, n = arbitrary natural number, λ = wavelength of X-ray beam). Then, the energy of the incident X-ray beam 13 can be changed with a large degree of freedom according to the measurement depth of the sample 20 and the like.

In this embodiment, since the surface angle of only the asymmetrical reflection crystal 18b among the two asymmetrical reflection crystals 18a and 18b can be adjusted by driving the piezo actuator 45, the two asymmetrical reflection crystals 18a and 18b can be adjusted. It is possible to compensate for the angular deviation from the incident angle of the X-ray beam 13 required for causing diffraction in the asymmetrical reflection crystal 18b caused by the rotation of the first support shaft 42 around the first support shaft 42. It is possible.

Further, in this embodiment, since the surface angle of the asymmetrical reflection crystal 18b is adjusted by the solid actuator such as the piezo actuator 45, it is reduced to 1/100.
The angle can be adjusted with high accuracy on the order of seconds, and the mechanism for adjusting the surface angle of the asymmetric reflective crystal 18b has a small and simple configuration. Therefore, two asymmetric reflective crystals 1
8a and 18b can be arranged sufficiently close to each other. In addition, as a solid actuator,
For example, an actuator having a magnetostrictive element or the like in addition to the piezo actuator 45 may be used.

As shown in FIGS. 3 and 7, in this embodiment, two support shafts 42, 4 of crystal holder 33 are provided.
3 and the two support shafts 42 and 43 of the crystal holder 34 are orthogonal to each other, so that these two crystal holders 33 and 34 do not interfere with each other at the base 41 and the mounting portions 32a and 32b. The crystal stage 43a at the tip of the support shaft 43 and the crystal stage 42a at the tip of the support shaft 42 of the crystal holder 34 can be brought close to each other. Thereby, the asymmetric reflection crystal 18 of the crystal holder 33
b and the asymmetric reflection crystal 18c of the crystal holder 34 can be arranged sufficiently close to each other, so that the X-ray microbeam generation unit 16 of the present embodiment has an extremely small diameter (1.0 to 1.5 μm). X-ray microbeam with a small divergence angle (about 1 to 2 seconds).

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various design changes are possible as long as they are described in the appended claims. Things. For example, in the above embodiment, two asymmetric reflective crystals are used in each of the horizontal and vertical directions, but three or more asymmetric reflective crystals may be used in each direction. Further, as the asymmetric reflection crystal, not only a silicon single crystal but also other known ones can be used. In addition, the examples shown in FIGS. 3 to 6 are examples in which the present invention is embodied, and various mechanisms can be considered as a specific device configuration for supporting the asymmetric reflective crystal.

[0033]

As described above, according to the first aspect, an X-ray microbeam having a sufficiently small diameter and a small divergence angle in each of two directions substantially orthogonal to each other is generated by using an asymmetric reflection crystal. It becomes possible. This allows
For example, it is possible to analyze the local distortion of a fine electronic device such as a compound semiconductor laser element with high accuracy, and to improve the manufacturing process of the electronic device based on the data of the distortion analysis. Therefore, it is expected that the product yield will be greatly improved.

According to the second aspect, since the relative positional relationship between the two asymmetrical reflection crystals with respect to the incident X-ray can be changed with a large degree of freedom, the energy of the incident X-ray can be changed according to the measurement depth of the sample. It can be changed with a large degree of freedom in response. According to the third aspect, it is possible to arrange the first and second asymmetric reflection crystals and the third and fourth asymmetric reflection crystals sufficiently close to each other. According to the fourth aspect, it is possible to arrange the second asymmetric reflection crystal and the third asymmetric reflection crystal sufficiently close to each other to generate an X-ray micro beam having a smaller diameter and a smaller divergence angle. Will be able to

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining the principle of asymmetrical reflection of X-rays according to the present invention. .

FIG. 2 is a schematic configuration diagram of an optical system of an X-ray analysis apparatus including an X-ray microbeam generation unit according to one embodiment of the present invention.

FIG. 3 is a perspective view of a support mechanism of an asymmetrical reflection crystal mounted on the X-ray analyzer shown in FIG.

FIG. 4 is a side view of a crystal holder included in a support mechanism of the asymmetrical reflection crystal.

5 is a plan view of the crystal holder shown in FIG.

6 is an enlarged view of the vicinity of the tip of a piezo element in the crystal holder shown in FIG.

FIG. 7 is a schematic diagram of a main part of the support mechanism depicted in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silicon single crystal 2 Incident X-ray beam 3 Diffracted X-ray beam 10 X-ray analyzer 11 Synchrotron radiation beam 12 Spectroscope 13 X-ray beam 15 Slit 16 X-ray micro beam generation part 18a-18d Asymmetric reflection crystal 20 Sample 24 Scintillation counter Reference Signs List 30 support mechanism 31 main body 32a, 32b mounting part 33, 34 crystal holder 41 base 42 first support shaft 43 second support shaft 45 piezo actuator

Claims (4)

[Claims] 1. An X-ray microbeam generating apparatus for generating an X-ray microbeam using an asymmetric reflective crystal having a surface not parallel to a crystal lattice plane, comprising: a first asymmetric reflective crystal; The second asymmetrical reflection crystal on which the diffracted X-rays by the first asymmetrical reflection crystal are incident is supported such that the beam widths of the X-rays reflected by the second asymmetrical reflection crystal are both reduced in the first direction. A first crystal support member capable of adjusting the surface angles of the first and second asymmetrical reflection crystals, a third asymmetrical reflection crystal on which diffracted X-rays by the second asymmetrical reflection crystal are incident, and A fourth asymmetric reflection crystal on which the diffracted X-rays by the third asymmetric reflection crystal are incident;
While supporting the beam widths of the X-rays reflected by them so as to be reduced in a second direction substantially perpendicular to the first direction, the supported third and fourth asymmetrical reflection crystals are supported. X having a second crystal support member capable of adjusting the surface angle respectively.
Line microbeam generator. 2. A first adjustment mechanism, wherein the first crystal support member adjusts a surface angle of the first and second asymmetrical reflection crystals simultaneously by rotating the first and second asymmetric reflection crystals about the same axis; A second adjusting mechanism for adjusting a surface angle of only one of the first and second asymmetrical reflection crystals, wherein the second crystal support member is provided with the third and fourth asymmetrical reflection crystals. A third adjusting mechanism for simultaneously adjusting the surface angle by rotating the mirrors about the same axis, and a fourth adjusting mechanism for adjusting the surface angle of only one of the third and fourth asymmetrical reflection crystals. The X-ray micro beam generating apparatus according to claim 1, further comprising a mechanism. 3. The apparatus according to claim 2, wherein the second adjustment mechanism and the fourth adjustment mechanism each include a solid actuator for adjusting a surface angle of the asymmetric reflection crystal. X-ray microbeam generator. 4. The first crystal support member and the first crystal support member such that the support axes of the first and second asymmetrical reflection crystals and the support axes of the third and fourth asymmetrical reflection crystals are orthogonal to each other. The X-ray microbeam generating apparatus according to any one of claims 1 to 3, wherein two crystal support members are arranged.