JPS6382350A - X ray crystal diffraction apparatus - Google Patents

Abstract

PURPOSE:To facilitate measurement of a distribution of mosaic structures of a crystal, by providing a slit with the width of 15-200mum preferably, 20-90mum in front of a window section of a counter tube. CONSTITUTION:It is necessary that a holder 4 for holding a sample single crystal is rotatable when a locking curve is obtained. X rays radiated from an X ray tube 1 are spectrally analyzed with a single crystal 2 for spectroscopy so that X rays with a desired wavelength are made to irradiate a sample single crystal. The counting tube 5 is held movably on the circumference of a circle centered on the holder 4 and a slit 6 with the width 15-200mum is provided in front of window section of the counting tube 5. To measure a distribution of mosaic structures, first, the locking curve is measured using no slit 6, the counting tube 5 is fixed at a position where the peak thereof is detected and subsequently, the slit 6 is mounted to measure the locking curve by turning the sample single crystal. A half value breadth of the locking curve thus obtained is a parameter indicating the degree of the distribution of mosaic structures.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The apparatus of the present invention relates to an X-ray crystal diffraction apparatus suitable for measuring the distribution of a mosaic structure of a crystal.

"Prior Art" Compound single crystals such as GaAs are generally produced by adding impurities,
Since the lattice constant changes easily due to heat treatment or the like, even the same single crystal has a distribution of lattice constants.

Furthermore, the crystals of these compounds also have a so-called mosaic structure consisting of fine regions with orientation distribution caused by plastic deformation.

Measure these distributions, especially the fine structures such as mosaic structures.1. Evaluating the jlt crystal is important when manufacturing various semiconductor devices using our single crystal.

Conventionally, these measurements have been carried out using the Xm two-piece method or the Xi three-piece method.
No. 1255-1259 (1972)].

That is, by these methods, the sample single crystal was rotated with respect to the incident X#a, and the above distribution was evaluated from the half-width of the so-called rocking curve, which is a change curve of the intensity of the diffraction X#Q with respect to the rotation angle. .

However, in the method of evaluation from the half-width of the rocking curve, in the case of a single crystal compound having a mosaic structure, the half-width does not include the mosaic structure and the lattice constant. It was difficult to measure only the distribution of the mosaic structure, as the effects of both distributions were included.

[Means for Solving the Problems] As a result of extensive research aimed at developing an X-ray crystal diffraction device that can easily measure the distribution of mosaic structures, the present inventors have developed the present invention. It has been reached.

The above object of the invention is to provide at least one microfocus X-ray tube.
In an This is achieved by a device with a 15-200 μm wide slit in the front of the tube window.

The apparatus of the present invention will be explained based on FIG.

Figure tpJ1 is a layout diagram showing the layout of each part of the device of the present invention.

In FIG. 1, 1 is a microfocus X-ray tube.

The X#a tube used in the device of the present invention needs to have a minute focus. This is because it is necessary to use a narrow X-ray beam in order to improve the resolution and avoid the influence of sample At crystal bending.

Note that the area of the focal plane of the microfocus X-ray tube is
When the σ plane on the tarp is projected onto a plane perpendicular to the direction of the ray bundle of l, the area of the focal plane is lX
Less than 10'μm2, preferably 4X10'' to 5X10
'A range of 62 μm is appropriate.

The xiw may be of an enclosed type or an assembled type.

The material of the tarded material is appropriately selected depending on the wavelength of the wavelength Xm.

The wavelength of X-rays suitable for measurement differs depending on the type a of the sample crystal, but compounds consisting of elements of group IIIb and group Vb of the periodic table, such as Si, GaAs, and GaP,
When measuring a single crystal of a so-called III-V compound, α for Cu- or α2#a for Cu- is usually used. In this case, copper is used as the tarded material.

2 is a single crystal for spectroscopy. The spectroscopic single crystal 2 is an X-ray I
It is used to separate the X-rays emitted from r1T1 into their spectra. That is, X +lQ l:1m
On the other hand, it functions as a 4R lattice.

At least one single crystal for spectroscopy is used. Unless a single crystal for spectroscopy is used, X-rays cannot be made monochromatic, which is not preferable.

In general, increasing the number of single crystals used for spectroscopy improves the wavelength purity of monochromatic Xa, but the intensity decreases, so the number should be selected as appropriate.

The distance between the X491 tube 1 and the single crystal for spectroscopy 2 is 100~SO
O+n is normal.

In order to easily adjust the angle between the X-ray tube 1 and the X-ray tube 1, it is preferable to use a rotatable holder.

The relative arrangement of the single crystal for spectroscopy and the sample single crystal may be such that the sample single crystal is irradiated with X-rays of a desired wavelength.

The spectroscopy-m single crystal is preferably one that has a small difference in lattice constant from the sample single crystal. For example, when measuring a GaAs single crystal, it is preferable to use a GaAs or Si single crystal because measurement accuracy improves.

3 is a slit. The slit 3 is used as necessary to extract only the required wavelength of X-rays from the spectrum of the X-rays obtained by the spectroscopic +1j crystal 2. The width of the slit is typically 100-500-μm.

3 is preferable since it is possible to appropriately select the required X-ray propagation by installing the spectroscopic single crystal 2 movably on the circumference of a circle centered on it.

Also, X-ray Ii? In order to prevent the spread of the X#1 flux generated in 1, a slit may also be provided at the opening of the X-ray tube 1 and the single crystal for spectroscopy 2.

4 is a holder. Holder 4 is used to hold sample J) crystals.

When obtaining a rocking curve, it is necessary to rotate the sample single crystal, so the holder 4 needs to be rotatable. Further, it is desirable that the rotation angle can be measured accurately.

5 is a counter. Count'I? 5 is used to measure the intensity of diffracted X-rays.

The counter '175 needs to be held movably on the circumference of a circle centered on the holder 4. This is to measure the distribution of diffraction intensity in the moving direction of the counter tube 5.

Further, it is desirable that the counter tube 5 be mounted on a goniometer in order to read the movement angle thereof.

As the counter 5, an Iga-Muller counter or a scintillation counter is usually used.

The distance between the counter tube 5 and the holder 4, that is, the path length of XIQ, is usually 100 to 500III6.

6 is a slit. The slit 6 must be provided in front of the window of the counter tube 5. Slit 6 and count 1
The spacing between the i75 windows is preferably 30+nm or less, more preferably 1 to 20+am.

If the slit 6 is not provided, it will not be possible to separate and measure only the mosaic structure distribution of the sample single crystal, so the slit 6 is essential.

The slit width of the slit 6 is preferably in the range of 15 to 200 μm, preferably 20 to 90 μm. If the slit width is less than 15 μto, the intensity of the X-rays incident on the counter W5 becomes weak, and the accuracy of intensity measurement decreases.

In addition, if it exceeds 200 μI, it becomes difficult to separate and measure the lattice constant distribution and the mosaic structure distribution, so both are not preferred (the material of the 1° slit 6 is not particularly limited, such as iron, copper, or other metal material). However, if a thin plate of a single crystal of a -V group compound such as GaAs is used and its cleavage plane ((110) plane) is used, a precise slit can be easily produced.

It is preferable that the slit width of the slit 6 is adjustable.

7 is a dotted line indicating the path of the X-ray, and is drawn for convenience of explanation.

Embodiment An embodiment of the apparatus of the present invention will be described with reference to a case where a GaAs (400) surface is measured.

As the Xm tube, an X-ray tube with a Cu tarde whose focal plane was 50μ+n×50μτn (focal plane area 2.5×10′μ×2) was used.

A Si single crystal was used as the single crystal for spectroscopy.

The plane orientation of the incident plane of the single crystal was set to the (220) plane.

Note that CuKCl rays were used as the X-rays for measurement.

The path length between the X-ray tube and the single crystal for spectroscopy is 300 +n+n
And so.

The path length of Xm between the sample single crystal holder and the single crystal for spectroscopy was set to 20IIIO. In addition, the X-ray tube and spectroscopy Jl.
A slit with a slit width of 100 μm was provided between the i-crystals and between the single crystal for spectroscopy and the sample single crystal.

〃A-- A slit with a slit width of 30 μT11 was installed at a position of 10+am of the curved surface of the window of the Mueller counter tube. The slit was made by cutting a GaAs (100) wafer.

The path length between the sample single crystal and the Gai-Mueller counter was 344 square meters.

The distribution of the lattice constant and the distribution of the mosaic structure of the GaAs single crystal were measured using an apparatus that satisfies the specifications listed in 2.

To measure the distribution of the mosaic structure, the rocking curve was measured without providing a slit in the curved surface of the window of the counter, and the counter was fixed at the position where the peak was detected. Next, attach a slit △￥C to the front of the window of the Ei counter.
The rocking curve was measured by rotating the sample single crystal.

The half-width of the obtained rocking curve, Δθ.

is a parameter representing the degree of mosaic structure distribution.

In the case of the above sample, Δθ1 was 6.71.

Generally, in a perfect crystal, Δθ1 is 0, and as the distribution of the mosaic structure increases, Δθ1 increases.

The lattice constant distribution was measured in 2θ/θ mode by installing a slit in front of one of the windows of the counter. If Δθ2 is a parameter representing the lattice constant distribution, the half-width of the obtained curve corresponds to 2Δθ2.

In the case of the above sample, Δθ2 was 25.5''.

When the rocking curve of the above sample was measured without providing a slit in front of the counter, its half-width was 22''.This value is determined by the influence of the lattice constant distribution in addition to Δθ. It is a value that includes

"Effects of the Invention" The VC arrangement of the present invention has the following effects and has great industrial utility value.

(1) As a result of providing a slit in the front of the counter window, the distribution of the mosaic structure can be made independent of the lattice constant distribution, and
Can be easily measured.

Therefore, a heteroepitaxial structure in which a Gu, -xAIxΔS mixed crystal layer, etc. is epitaxially grown on a GaAs substrate.
Wafer evaluation becomes extremely easy.

(2) Since we use finely focused X-rays from a microfocus xi tube, the wafer bends by 16'! − can be reduced.

(3) As a result of providing the slit, the resolution is improved even when measuring in other measurement modes such as 2θ/θ mode.

4 WJfit Explanation of the Drawings FIG. 1 is a layout diagram showing the arrangement of each part of the apparatus of the present invention.

1...Microfocus X-ray tube 2...Single crystal for spectroscopy 4...Holder 5...Counter tube 6...Slit Patent applicant Ito Itsu (and 2 others) Agent
Patent Attorney Hase - (1 other person) Ta 1 Figure

Claims (4)

[Claims] (1) A microfocus X-ray tube, at least one single crystal for spectroscopy, a holder that rotatably holds a sample single crystal, and a holder that is held movably on the circumference of a circle centered on the rotation axis of the holder. 1. An X-ray crystal diffraction apparatus having a counter, characterized in that a slit with a width of 15 to 200 μm is provided in the front face of a window of the counter. (2) The device according to claim 1, wherein the width of the slit is 20 to 90 μm. (3) The device according to claim 1 or 2, wherein the distance between the slit and the window of the counter is 10 mm or less. (4) The device according to claim 1, 2, or 3, wherein the slit is constructed using a thin plate of a compound single crystal consisting of group IIIb and group Vb elements.