JP2000081399A - X-ray diffraction apparatus for membrane sample - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a membrane X-ray diffraction apparatus capable of obtaining the crystal data of the minute area in a polycrystal membrane sample. SOLUTION: Primary X-rays 4 of a single wavelength emitted from a fixed X-ray source 9 pass through an irradiation area restriction means 7 as almost parallel beam to irradiate the minute area of the surface of the membrane 1 formed on a substrate 2. Diffracted X-rays 5 by the membrane 1 pass through an emission angle restriction means 8 to be guided to an X-ray detector 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an X-ray diffraction apparatus for a thin film sample.

[0002]

2. Description of the Related Art A method of examining a crystalline state of a substance by X-ray diffraction is a very effective evaluation means in developing a new material and a new application form of the material. In particular, in the fields of optics, electronics, and the like, materials are often used in the form of a thin film, and it has become important to evaluate in the form of a thin film.

In order to measure the X-ray diffraction of a thin film, it is important to efficiently detect the diffracted X-rays from the thin film and to suppress as much as possible the scattered X-rays from the substrate material which causes the background.

A method widely used for X-ray diffraction measurement of a thin film is a method called the Zeeman-Bohlin method, for example, see [R. Feder and BS Berry, See
man-Bohlin X-Ray Diffraction for Thin Films,
Journal of Applied Crystallography, 3 (197
0) 372].

The principle will be described with reference to FIG. In the Zeeman-Bohrin method, the incident angle (α) of the primary X-ray 4 is fixed with respect to the surface of the sample 3, and the diffracted X-ray 5 emitted at various angles (2θ) is converted only by the X-ray detector 6. Is turned to detect and record. The search for penetration of the primary X-ray into the sample depends on the incident angle α. By setting the incident angle α to a very small value, the search for penetration of the primary X-ray into the sample can be reduced, and the contribution of the scattered X-ray from the substrate 2 can be extremely reduced. As a result, the thin film 1 near the surface of the sample 3
It is possible to selectively detect the diffracted X-rays from.
According to this method, for example, when the incident angle α is set to 0.5 °, an X-ray diffraction pattern of a polycrystalline thin film having a thickness of about 10 nm can be easily obtained.

[0006]

In the above-mentioned Zeeman-Bollin method, the width of the primary X-ray beam W
Is used, the width of the X-ray irradiation area on the sample surface is represented by W / sin α, and when the incident angle α is reduced, the X-ray beam is applied to a wide area of the sample surface. . For example, when W = 0.1 mm and α = 0.5 °, the width of the X-ray irradiation area on the sample surface is about 11 mm. Therefore, in a conventional thin-film X-ray diffractometer (see, for example, JP-A-60-263841) as shown in FIG.
Only the average information of a thin film having a relatively large area could be obtained.

On the other hand, in the case of a thin film material, several μm to several hundred μm are used.
In many cases, the structure changes in the region of m, and the function corresponding thereto is expressed. In the conventional thin film X-ray diffractometer, it was impossible to distinguish and measure the structure of such a minute region.

Accordingly, the present invention has been made in view of the problems of the conventional thin film X-ray diffractometer, and has as its object to provide a thin film X-ray diffractometer capable of obtaining crystal information of a minute region in a polycrystalline thin film sample. I have.

[0009]

SUMMARY OF THE INVENTION The present invention has been made by intensive studies to achieve the above-mentioned object, and has the following configuration.

That is, according to the present invention, when a crystalline thin film sample formed on a substrate is irradiated with X-rays, the crystal information of the sample is detected by detecting diffracted X-rays generated by diffraction of the sample. An X-ray diffraction apparatus for a thin film sample to be obtained, comprising: an irradiation area limiting means for limiting an irradiation area of irradiation X-rays on the surface of the sample; and an emission angle of the diffraction X-rays with respect to a plane including the sample surface being kept at a small angle. X-ray detecting means for detecting the diffracted X-rays.

Further, when detecting the diffracted X-ray,
Holding the sample as a means for keeping the emission angle of the diffracted X-rays at a small angle with respect to the plane including the surface of the sample,
A sample rotation mechanism for rotating the sample around a rotation axis coinciding with the surface of the sample, and emitting the diffracted X-rays to a plane including the sample surface, rotating around the rotation axis in conjunction with the sample; And an emission angle limiting means for limiting the angle to a minute angle.

In the present invention configured as described above, the irradiation X-rays on the surface of the sample are passed through the irradiation area limiting means, whereby the irradiation X-rays are restricted, and the surface of the thin film formed on the substrate is exposed. It is irradiated to a minute area. This makes it easy to obtain crystal information in a minute region of the thin film material from several μm to several hundred μm.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram for explaining the principle of the present invention. The primary X-rays 4 of a single wavelength emitted from the fixed X-ray source 9 pass through the irradiation area limiting means 7 as a substantially parallel beam, and are formed in a minute area on the surface of the thin film 1 formed on the substrate 2. Is irradiated. The X-rays 5 diffracted by the thin film 1 are guided to an X-ray detector 6 through an emission angle limiting means 8.

As the X-ray source 9, monochromatic synchrotron radiation can be used in addition to various X-ray tubes.
As the irradiation area limiting means 7, a slit system including one or a plurality of slits, a condensing system including one or a plurality of X-ray reflecting mirrors, various collimators, an X-ray conduit using a capillary, and the like are used. Can be. The size of the primary X-ray irradiation area can be selected in the range of several μm to several mm by appropriately using these irradiation area limiting means. The sample 3 is held by a sample rotating mechanism (not shown). As the emission angle limiting means 8, a slit installed at a predetermined position, an X-ray shielding member, or the like is used. The emission angle limiting means 8 rotates in conjunction with the rotation of the sample, so that the angle of extraction of the diffracted X-rays is kept constant with respect to a plane including the sample surface. As the X-ray detector 6, a scintillation counter and a proportional counter tube can be used together with a mechanism that turns in conjunction with sample rotation. Alternatively, in the case of a position-sensitive proportional counter, an imaging plate, a photographic film, or the like, the detector can be used without moving.

[0016]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to specific examples, but the present invention is not limited to these examples, and each element within a range in which the object of the present invention is achieved. This also includes those in which substitutions or design changes have been made.

(Embodiment 1) FIG. 2 is a view showing a first embodiment of the present invention. In FIG. 2, the same parts as in FIG.
The same numbers are given as.

In this embodiment, a rotating anti-cathode X-ray tube 19 using Cr as a negative electrode is used as an X-ray source (indicated by reference numeral 9 in FIG. 1).
It was used. The rotating anti-cathode X-ray tube 19 is set to a tube voltage of 40 kV,
It was driven at a tube current of 300 mA. The X-ray focus was a line focus. In the arrangement of this embodiment, the effective focus width is 0.1
mm and the length is 10 mm.

As the irradiation area limiting means (indicated by reference numeral 7 in FIG. 1), a slit 11 having a width of 300 μm is provided at a distance of 95 mm from the X-ray focal point. The Cr characteristic X-ray, which is the primary X-ray 4 from the fixed rotating anti-cathode X-ray tube 19, passes through the slit 11 and
90 mm from the surface of the sample 3. Sample 3
Is held by a sample holder (not shown) on the goniometer 10 which is a sample rotating mechanism. At this time, the rotation center axis of the goniometer 10 passes through the surface of the sample 3 and exists at the center of the primary X-ray irradiation area on the sample surface.

Assuming that the incident angle of the Cr characteristic X-rays 14 on the surface of the sample 3 is α, the width (horizontal direction) of the primary X-ray irradiation area on the surface of the sample 3 is given by 300 / sin α (μm). In the present embodiment, the width (horizontal direction) of the primary X-ray irradiation area measured near α = 60 ° is about 350 μm when the incident angle α = 60 °.

As emission angle limiting means (indicated by reference numeral 8 in FIG. 1), slits 12 and 13 each having a width of 150 μm are provided at positions 185 mm and 230 mm from the center of the sample, respectively. A scintillation counter 16 is provided as a line detector.
Slits 12 and 13 and scintillation counter 16
Are integrated, and rotate around the sample rotation axis in conjunction with the rotation of the sample 3 by the goniometer 10. The slit mechanism including the slits 12 and 13 reduces the angle of emergence β of the diffracted X-rays 5 from the sample 3 from the sample surface to about 0.07.
It can be specified with a resolution of 5 °.

Sample 3 was prepared by forming a 5 nm-thick palladium thin film on a quartz substrate, and the measurement of X-ray diffraction was performed using the apparatus of this embodiment. While maintaining the condition of a small emission angle β = 0.5 ° with respect to the plane including the sample surface, the diffraction X is rotated while rotating the slits 12 and 13 and the scintillation counter 6 in conjunction with the rotation of the sample 3. The line intensity was measured. An X-ray diffraction pattern having a diffraction angle (2θ) in the range of 50 ° to 70 ° could be recorded, and the diffraction peak of palladium was clearly observed.

According to this embodiment, the X-ray diffraction pattern of a region having a width of 350 μm can be measured for a thin film having a thickness of 5 nm.

(Embodiment 2) FIG. 3 is a view showing a second embodiment of the present invention. 3, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals as those in FIGS.

In this embodiment, a rotating anti-cathode X-ray tube 19 using Cr as a negative electrode was used as an X-ray source. The rotating anti-cathode X-ray tube 19 was driven at a tube voltage of 40 kV and a tube current of 300 mA. The X-ray focal point is a point focus. In the arrangement of this embodiment, the effective focal point has a width of 1 mm and a length of 1 mm.

A collimator 14 having a diameter of 50 μm as irradiation area limiting means (indicated by reference numeral 7 in FIG. 1) is
It was installed at a distance of 250 mm from the line focus. The Cr characteristic X-ray, which is the primary X-ray 4 from the fixed rotating anti-cathode X-ray tube 19, passes through the collimator 14 and is incident on the surface of the sample 3 at a position 5 mm from the exit of the collimator 14. . The sample 3 is held in a sample holder on a goniometer 10 which is a sample rotating mechanism. The size of the primary X-ray irradiation area is determined by the geometrical arrangement of the X-ray source, collimator, and sample. In the case of this embodiment, the diffraction angle is changed from 40 ° to 60 °.
It was confirmed by observing the emission of X-rays on the fluorescent plate with an optical microscope that the primary X-ray irradiation area did not exceed 100 μm even if the angle was changed to °.

As an emission angle limiting means (indicated by reference numeral 8 in FIG. 1), a lead plate having a thickness of 1 mm is used as the X-ray shielding member 15.

The X-ray shielding member 15 is fixed to a holder (not shown) like the sample 3, and the positional relationship with the sample does not change. The X-ray shielding member 15 blocks X-rays emitted from the sample at an emission angle equal to or greater than a certain angle, and does not enter the X-ray detector. In this embodiment, the X-ray shielding member 15 is provided so that X-rays having an emission angle of 5 ° or more are cut.

X-ray detector (indicated by reference numeral 6 in FIG. 1)
, A position-sensitive proportional counter 17 was used.

Sample 3 was prepared by forming a 5 nm-thick palladium thin film on a quartz substrate, and the X-ray diffraction was measured using the apparatus of this embodiment. While rotating the sample, the intensity of the diffracted X-ray was measured. An X-ray diffraction pattern having a diffraction angle (2θ) in the range of 50 ° to 70 ° could be recorded, and the diffraction peak of palladium was clearly observed.

According to the present embodiment, an X-ray diffraction pattern of a region having a diameter of 100 μm or less can be measured for a thin film having a thickness of 5 nm.

[0032]

As described above, according to the present invention, the X-ray source passes the X-ray through the irradiation area limiting means to irradiate the sample surface, and the X-ray diffracted by the thin film on the sample surface emits the X-ray angle limiting means. By passing the light through the X-ray detector, the X-ray diffraction pattern of a minute region of the thin film sample can be measured.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one example of an X-ray diffraction apparatus for a thin film sample according to the present invention.

FIG. 2 is a schematic view showing a first embodiment of the X-ray diffraction apparatus of the present invention.

FIG. 3 is a schematic view showing a first embodiment of the X-ray diffraction apparatus of the present invention.

FIG. 4 is a schematic diagram showing an example of a conventional thin film X-ray diffraction apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thin film 2 Substrate 3 Sample 4 Primary X-ray 5 Diffracted X-ray 6 X-ray detector 7 Irradiation area limiting means 8 Emission angle limiting means 9 X-ray source 10 Goniometer (sample rotating mechanism) 11 Irradiation area limiting slit 12 Slit 13 Emission Angle limiting slit 14 Collimator 15 Emission angle limiting shield plate 16 Scintillation counter 17 Position sensitive proportional counter 19 Rotating anti-cathode X-ray tube α Incident angle of primary X-ray to sample surface β Emission angle of diffracted X-ray to sample surface 2θ sample Angle of X-ray diffraction by W W width of primary X-ray beam

Claims (4)

[Claims] 1. A crystalline thin film sample formed on a substrate
An X-ray diffractometer for a thin film sample, which obtains crystal information of the sample by detecting diffracted X-rays generated by the sample when irradiated with the X-ray; A thin film, comprising: an irradiation area limiting means for limiting the X-rays; and an X-ray detecting means for detecting the diffracted X-rays while keeping an emission angle of the diffracted X-rays to a plane including the sample surface at a small angle. X-ray diffractometer for sample. 2. When the diffracted X-rays are detected, the sample is held as a means for keeping an emission angle of the diffracted X-rays at a minute angle with respect to a plane including the surface of the sample. A sample rotation mechanism for rotating the sample around a rotation axis coinciding with a surface, and a rotation around the rotation axis in conjunction with the sample, so that the emission angle of the diffracted X-ray with respect to a plane including the sample surface is minute. 2. An X-ray diffraction apparatus for a thin film sample according to claim 1, further comprising an emission angle limiting means for limiting the angle to an appropriate angle. 3. The X-ray diffraction apparatus for a thin film sample according to claim 2, wherein said emission angle limiting means is a slit mechanism. 4. The X-ray diffraction apparatus for a thin film sample according to claim 2, wherein said emission angle limiting means is an X-ray shielding member.