JP2000275192A - X-ray diffraction apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To arbitrarily set resolving power in the measurement of the diffraction pattern of diffracted X-rays generated when a sample is irradiated with X-rays. SOLUTION: In the X-ray diffraction apparatus, a sample 3 is held on a goniometer 12 having a sample rotating mechanism and the incident angle ωof primary X-ray 4 from an X-ray source 7 is regulated by the sample rotating mechanism. A position-sensitive type proportion counter 6 is provided in order to measure the emitting angle α of diffracted/scattered X-rays 5 from the sample 3 to be arranged on a rectilinear stage 11 movable in a Tx-direction and a Ty-direction and changes in its resolving power corresponding to the distance L with the sample 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray diffractometer capable of measuring X-ray diffraction at an arbitrary resolution.

[0002]

2. Description of the Related Art Since various device materials in recent years are formed in the form of a thin film, a method of examining the crystal structure of the thin film using X-ray diffraction is frequently used. In addition, the X-ray diffraction method has advantages in that the measurement atmosphere can be freely controlled, non-destructive measurement can be performed, and diffraction intensity can be relatively easily quantified.

When evaluating the structure of a thin film using X diffraction, it is important to detect diffracted X-rays from the thin film efficiently and to reduce the background from the substrate as much as possible. For this purpose, the following two methods are generally used.

(1) Oblique incidence method: A method in which the angle of incidence of X-rays on a sample surface is limited to several degrees or less, and a detector is scanned in a plane perpendicular to the surface.

(2) Oblique emission method: The incidence angle of X-rays on the sample surface is set relatively large, the detector is scanned in a plane perpendicular to the sample surface, and X-rays are detected near the sample surface. How to set. Compared to the oblique incidence method, by setting the size of the primary X-ray beam appropriately, it becomes possible to measure a minute area.

[0006] In any of the methods, a typical method of detecting X-rays is to use a scintillation counter or the like.
In general, measurement is performed by scanning a dimensional detector.

[0007]

The resolution at the time of evaluating the structure of a thin film material by X-ray diffraction measurement is determined as follows.

In the measurement by the grazing incidence method, in order to measure the diffraction profile of the X-ray diffracted by the sample at a high resolution, a thin foil is usually placed immediately before the detector in the scanning direction of the detector. A so-called solar slit mounted so as to be vertical is used. The solar slits must be completely stacked in parallel, keeping stainless steel foil or the like having a thickness of about 50 μm at an interval of about 50 to 100 and close to 100 μm. In order to select and measure the resolution appropriately, it is necessary to replace the solar slit,
Achieving a certain level of resolution or more is difficult from the technical point of view of the solar slit. When used in a normal laboratory system, it is used at a fixed resolution of about 0.25 °.

On the other hand, in the measurement by the oblique emission method, since the X-rays to be detected are almost parallel components emitted near the sample surface, the resolution of the X-ray detection is usually determined by using a slit or the like. To determine. Therefore, the resolution is determined by the width of the slit used, and in a normal arrangement, the resolution is 0.1 mm.
The resolution is about 05 °. Therefore, in order to appropriately select the resolution, it is necessary to exchange the slits, but it is impossible to set the resolution appropriately unless a variable slit or the like is used.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and it is possible to arbitrarily set a resolution in measuring a diffraction pattern of a diffraction X-ray generated when a sample is irradiated with an X-ray. It is an object of the present invention to provide an X-ray diffractometer capable of being used.

[0011]

In order to achieve the above object, an X-ray diffractometer according to the present invention detects a diffracted X-ray generated by diffracting a sample when the sample is irradiated with X-rays. An X-ray diffraction apparatus for obtaining structural information of the sample, comprising: an incident angle defining means for defining an incident angle of irradiation X-rays on a surface of the sample; and an emission angle of the diffracted X-rays on a surface including the surface of the sample. X to measure
It is characterized by having a line detecting means and a resolution changing means for changing the resolution of the X-ray detecting means.

In the X-ray diffractometer of the present invention configured as described above, the incident angle of the incident X-ray to the sample is defined by the incident angle defining means, and the output angle of the diffracted X-ray from the sample is set to X-ray.
X-ray diffraction profile is obtained by measuring with the line detecting means, and based on this, structural information near the sample surface can be obtained. Here, in the present invention, the resolution of the X-ray detecting means is arbitrarily set because the resolution changing means is provided.

As the X-ray detecting means, a position-sensitive proportional counter can be used, and in this case, the resolution changes according to the distance from the sample. Therefore, the resolution can be easily set by using the means for changing the distance between the position-sensitive proportional counter and the sample as the resolution changing means. Further, in order to improve the detection of diffracted X-rays by the position-sensitive proportional counter, the resolution changing means further includes:
It is preferable to change the position in the direction perpendicular to the direction in which the angle to the sample or the distance to the sample is changed.

[0014]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing an example of a sample measuring apparatus to which the present invention is applied. In this embodiment, the sample 3 in which the thin film 1 is formed on the substrate 2 is an object to be measured.

In FIG. 1, primary X-rays 4 of a single wavelength emitted from an X-ray source 7 are applied to the thin film 1 formed on a substrate 2 as substantially parallel beams. As means for converting the primary X-ray 4 into a parallel beam, a solar slit,
A four-crystal or two-crystal monochromator can be used. As the X-ray source 7, monochromatic synchrotron radiation can be used in addition to various X-ray tubes.

An irradiation area limiting means 8 is inserted between the X-ray source 7 and the sample 3. As the irradiation area limiting means 8, it is possible to use a normal slit, one or a plurality of X-ray reflection and collection optical systems, an X-ray conduit such as a capillary, or the like. The size of the irradiation area of the primary X-rays 4 on the sample 3 can be selected in the range of several μm to several mm by appropriately using these irradiation area limiting means 8.

The sample 3 is held on a goniometer 12 equipped with a sample rotating mechanism. By using this rotating mechanism, the incident angle ω of the primary X-ray 4 with respect to the surface of the sample 3 can be freely set. I can do it.

Primary X-rays 4 transmitted through the irradiation area limiting means 8
Are diffracted and scattered on the surface of the sample 3. The diffracted / scattered X-rays 5 pass through the shield 9 and are position-sensitive proportional counters 6 (PSPCs), which are X-ray detectors for measuring the exit angle of the diffracted / scattered X-rays 5.
nal Counter). In order to detect only the diffracted / scattered X-rays 5 from the sample 3, the shield 9 is installed so that X-rays and the like scattered from an extra area are not made incident on the position-sensitive proportional counter 6. That's why.

The position-sensitive proportional counter 6 has a direction (T _x direction) defining a distance L from the center of rotation of the sample 3 to the core wire 10 in the position-sensitive proportional counter 6, and a direction (T _x ) perpendicular thereto. _In order to be able to move freely in the ( _y direction), it is installed on a translation stage 11 as a resolution varying means in the present invention, which can move in each direction. For example, if the translation stage 11 can be controlled from outside,
The arrangement according to the measurement can be easily set.
The translation stage 11 may be rotatable in a plane parallel to the rotation plane of the sample 3 so that the angle of incidence of the diffracted / scattered X-rays 5 on the position-sensitive proportional counter 6 can be adjusted.

The position-sensitive proportional counter 6 itself can be set to be independently movable or can be set to be rotatable about the rotation center of the sample 3 as a rotation axis.

When the area where the diffracted X-rays are generated can be regarded as a point light source, the measurement resolution is the distance L from the center of rotation of the sample 3 to the core wire 10 in the position-sensitive proportional counter 6 and the position-sensitive proportional count. It is determined by the inherent resolution R of the tube 6 itself. Therefore, the resolution can be appropriately determined by changing the distance L from the rotation center of the sample 3 to the core wire 10 in the position-sensitive proportional counter 6.

A detector (position-sensitive proportional counter 6)
The X-rays are obliquely incident on both ends of, and the resolution is slightly lower than that near the center.

In using the ordinary position-sensitive proportional counter 6, the inside is replaced with a mixed gas of Ar and CH ₄ or the like, and the measurement is performed. For example, PR gas (Ar90
%, CH ₄ 10%), the counting efficiency of detection changes depending on the energy of the primary X-ray 4 used. For example, the energy is about 38% when using CuKα and about 54% when using CrKα.
Therefore, in order to perform detection more efficiently, it is preferable to use energy near CrKα.

In the actual measurement, first, the incident angle ω of the primary X-ray 4 with respect to the surface of the sample 3 is determined by driving the sample rotating mechanism of the goniometer 12 and fixed. Thereafter, the position-sensitive proportional counter 6 is installed at a position where the desired Bragg angle of the thin film 1 can be detected.

Then, while monitoring the diffraction peak,
The translation stage 11 is driven to move the position-sensitive proportional counter 6 in the _Ty direction so that the diffraction peak appears substantially at the center of the position-sensitive proportional counter 6. The diffraction peak does not necessarily need to appear at the center, but it is desirable to appear at the center in order to reproduce the diffraction peak more accurately.

Next, the position-sensitive proportional counter 6 is moved in the _Ty direction so as to obtain a desired resolution, an optimum arrangement is determined, and a diffraction peak is measured. As described above, the resolution can be set easily only by moving the position-sensitive proportional counter 6 in the _Tx direction.

[0028]

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.

(Example 1) The experimental arrangement in this example is the same as that in FIG. As the X-ray source 7, a rotating anti-cathode X-ray tube using Cu as a negative electrode was used. The rotating anti-cathode X-ray tube was driven at a tube voltage of 40 kV and a tube current of 200 mA.
The X-ray focus was a line focus. In the arrangement of the present embodiment, the width of the effective focal point is 0.05 mm and the length is 10 mm.

The irradiation area limiting means 8 has a width of 150 μm.
m slit was set at a position 100 mm from the X-ray source 7. The primary X-rays 4 generated from the X-ray source 7 pass through the irradiation area limiting means 8 and are irradiated on the sample 3 at a position 85 mm from the irradiation area limiting means 8. In this embodiment, the substrate 2
A palladium thin film formed by vacuum deposition as a thin film 1 on the quartz substrate is heated in the atmosphere,
The oxidized product was designated as Sample 3. By appropriately setting the incident angle ω of the primary X-ray 4 with respect to the surface of the sample 3, the oblique emission X
A line diffraction measurement was performed.

First, the position-sensitive proportional counter 6 whose effective length s of the core wire 10 is 50 mm is set at 20 mm from the rotation center of the sample 3.
When fixed at a position of 0 mm and subjected to oblique emission X-ray diffraction measurement, a diffraction pattern of 2θ = about 32 ° to 44 ° can be measured, and a diffraction peak due to metallic palladium and a diffraction peak due to palladium oxide can be measured. Both diffraction peaks were observed. The resolution in this arrangement is approximately 0.06 °
Met.

Further, in order to obtain information on metal palladium, the position-sensitive proportional counter 6 was moved to a position 500 mm from the center of rotation of the sample 3 and fixed to perform oblique emission X-ray diffraction measurement. In this arrangement, 2θ = 38 ° ~
The diffraction angle was measured up to about 43 °, and a peak around 2θ = 40.1 ° due to metallic palladium was observed. The resolution in this arrangement was approximately 0.02 °.

(Embodiment 2) The arrangement used in the experiment is Embodiment 1.
In the same manner as in the above, for the measured sample 3, an aluminum film was vacuum-deposited on a quartz substrate. Oblique emission X in this arrangement
A line diffraction measurement was performed. Primary X-ray 4 on the surface of sample 3
Was set to 38.0 °. The position-sensitive proportional counter 6 whose effective length s of the core wire 10 was 50 mm was fixed at a position 300 mm from the rotation center of the sample 3, and oblique emission X-ray diffraction measurement was performed. In this arrangement, a diffraction pattern from 2θ = about 34 ° to 43 ° could be measured, and a diffraction peak due to aluminum was observed. The resolution in this arrangement was approximately 0.04 °.

(Example 3) The experimental arrangement and sample 3 were the same as in Example 2, except that a rotating anti-cathode X-ray tube using Cr as a negative electrode was used as the X-ray source 7. Rotating anti-cathode X-ray tube,
It was driven at a tube voltage of 40 kV and a tube current of 200 mA. The X-ray focus was a line focus. In the arrangement of this embodiment, the effective focal point has a width of 0.05 mm and a length of 10 mm. Since the detection efficiency of the position-sensitive proportional counter 6 uses the characteristic X-ray of Cr, the data of the S / N ratio is shorter than that of the third embodiment measured using the characteristic X-ray of Cu. Could be obtained.

[0035]

As described above, according to the present invention, the resolution variable means for changing the resolution of the X-ray detecting means for measuring the angle of emission of the diffracted X-ray from the sample is provided. The resolution for obtaining the diffraction profile can be set arbitrarily. In particular, when the X-ray detecting means is a position-sensitive proportional counter, the resolution varying means
The resolution can be easily set as long as the distance of the position-sensitive proportional counter to the sample is changed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of a sample measuring device to which the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thin film 2 Substrate 3 Sample 4 Primary X-ray 5 Diffraction / scattered X-ray 6 Position sensitive proportional counter 7 X-ray source 8 Irradiation area limiting means 9 Shield 10 Core wire 11 Translation stage 12 Goniometer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G001 AA01 AA09 BA14 BA18 CA01 DA01 DA02 DA03 DA08 EA09 GA05 GA13 JA06 JA11 JA20 KA08 KA13 MA05 NA06 NA15 NA17 NA21 RA03 SA01 SA02

Claims (5)

[Claims] 1. An X-ray diffraction apparatus for obtaining structural information of a sample by irradiating the sample with X-rays and detecting diffracted X-rays generated by diffraction of the sample. Incident angle defining means for defining the incident angle of the irradiated X-ray to the X-ray; X-ray detecting means for measuring the emission angle of the diffracted X-ray with respect to the surface including the surface of the sample; and resolution of the X-ray detecting means. An X-ray diffraction apparatus, comprising: a resolution changing means for changing the resolution. 2. The X-ray diffraction apparatus according to claim 1, wherein said X-ray detection means is a position-sensitive proportional counter. 3. The X-ray diffraction apparatus according to claim 2, wherein said resolution changing means is means for changing a distance between said position-sensitive proportional counter and said sample. 4. The X-ray diffraction apparatus according to claim 3, wherein said resolution changing means changes an angle of said position-sensitive proportional counter with respect to said sample. 5. The X according to claim 3, wherein the resolution varying means is means for changing a position of the position-sensitive proportional counter in a direction perpendicular to a direction in which a distance from the sample is changed. Line diffractometer.