JPH03289547A - Method and apparatus for measuring grating constant - Google Patents

Abstract

PURPOSE:To make the change in grating constant continuous in two dimensions and to make the countermeasure at a place clear and accurate by emitting collimated monochromatic X rays, performing spectroscopy of diffracted rays from a sample to be measured in an angle-decomposing way, and observing the rays. CONSTITUTION:Collimated monochromatic X rays 14 are cast on a material to be measured 18. At this time, the sample 18 is fixed at a certain angle. With an analyzer 111 being rotated, a series of diffracted rays undergo spectroscopy in an angle-decomposing way, and the rays are observed in a microscopic way. When the sample 18 is fixed at another angle, the diffracted rays 19 from the samples can undergo spectroscopy in the angle-decomposing way at the other angle position. Thus, the change in lattice constant of a single crystal can be made continuous in two dimensions without the effect of the lattice surface, and countermeasure at a place can be made clear and accurate. In this way, the grating constant can be obtained in the minute region in the vicinity of transition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lattice constant measuring method and apparatus for detecting lattice constant non-uniformity in minute regions of single crystal materials, particularly in the vicinity of dislocations.

[Conventional technology]

The non-uniformity of the lattice constant of single crystal materials is, for example, GaAs
For compound semiconductor materials such as crystals, Ga and As
stoichiometry, and affects the nonuniformity of device characteristics. In particular, changes in stoichiometry in minute regions near dislocations significantly affect the nonuniformity of device characteristics.

Conventionally, as a method for measuring the lattice constant of a single crystal material, there is an X-ray bond method shown in FIG. Incident X-rays 21 are made incident on a sample 22, and diffraction lines 23 from the sample 22 are detected by a detector 2.
4 and measure the Black angle of the sample 22. In order to eliminate the influence of the lattice plane inclination, zero correction, etc., it is determined by the diffraction line 23 and the diffraction line 25 from the sample 22 on the opposite side. The lattice constant is determined from the Black angle.

[Problem to be solved by the invention]

However, because the conventional method measures the diffraction intensity curve using a narrowly focused X-ray beam, it is not possible to determine whether the location being measured is near a dislocation existing in a single crystal. . Furthermore, the information obtained is also discrete, and only a small portion of the information about the single crystal material can be obtained.

The object of the present invention is to eliminate such conventional drawbacks and provide a method and apparatus for observing changes in lattice constants two-dimensionally and continuously, with clear spatial correspondence.

[Means to solve the problem]

The present invention provides a lattice constant measurement method characterized by irradiating a sample to be measured with collimated monochromatic X-rays, diffraction lines from the sample to be measured are spectrally analyzed in an angle-resolved manner, and observed using diffraction microscopy. It is.

In addition, the equipment for realizing this method includes a monochromator and an X-ray of a specific wavelength selected by the monochromator.
A configuration comprising at least a collimator on which the X-rays are incident, a sample stage on which the sample to be measured is placed on which the asymmetrically reflected X-rays from the collimator are incident, and an analyzer for angle-resolved spectroscopy of diffraction lines from the sample to be measured. It has become.

〔Example〕

Zircrotron radiation has a powerful, continuous wavelength and is very useful as an X-ray source for crystal evaluation using diffraction phenomena. The present invention effectively utilizes the characteristics of synchrotron radiation. Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention.

After the synchtron radiation light 11 is shaped into an X-ray beam size by a slit, it is made monochromatic to a specific wavelength by a monochromator 13 installed in the first goniometer head and capable of rotation in ω-2θ. This monochromatic X! 14 is shaped into a beam size by a slit 15, and then enters a collimator 16 which is rotatable in ω-2θ and is installed in the second goniometer head. The reflection from the collimator 16 uses asymmetric reflection that exists obliquely with respect to the sample surface, and it is possible to reduce the divergence angle of the X-rays 17 emitted from the collimator 16 and widen the ray flux. The X-ray 17 is incident on a sample 18 installed in a third goniometer head capable of concave rotation in ω-2θ, and the diffraction line 19 from the sample 18 is installed in a fourth goniometer head capable of concave rotation in ω-2θ. After being angularly resolved into spectra by an analyzer 111, the light is observed using a diffraction microscope using a nuclear emulsion plate 112.

Now, when the sample 18 is fixed at a certain angle and a series of diffraction images are microscopically observed while the analyzer 111 is rotated one after another, the diffraction lines 19 from the sample 18 are analyzed by the analyzer 111 in an angle-resolved manner. becomes possible. Similarly, when a series of diffraction images are microscopically observed while fixing the sample 18 at different angles and sequentially rotating the analyzer 111, the analyzer 111 detects diffraction lines 19 from the sample 18 from different angular positions. It becomes possible to perform angularly resolved spectroscopy.

A series of such diffraction microscopic images is shown in Figure 3.
The lattice points where strong diffraction images were obtained at each location (A-D) inside the cell in the s-crystal are plotted in reciprocal space.
It is a diagram. In FIG. 3, A is an intermediate region between the cell wall where a dislocation network is formed and dislocations protruding to the crystal surface, B is an intermediate region between two dislocations that do not protrude to the crystal surface, C, D is a region where no dislocations exist inside the cell. In FIG. 4, the lattice points at each location show a band shape extending along the q8 axis, and the change in the lattice constant at each location can be determined from the shift of the midpoint. Furthermore, it is possible to determine the shift of the midpoint in the qy-axis direction and the change in the lattice plane at each location, and the change in the lattice constant and the change in the lattice plane can be determined separately.

〔Effect of the invention〕

According to the present invention, changes in the lattice constant of a single crystal can be determined continuously in two dimensions without being affected by lattice planes, and with clear local correspondence, for example, in minute regions near dislocations. For example, it has an effective effect in comparing the stoichiometry near dislocations in a GaAs single crystal and the characteristics of a semiconductor device.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a diagram of a conventional lattice constant measuring device, Fig. 3 is a diagram showing a cell structure in a GaAs crystal, and Fig. 4 is a diagram showing each location. FIG. 2 is a diagram in which lattice points from which strong diffraction images were obtained are plotted in reciprocal space. 11... Synchrotron radiation, 12... Slit, 13... Monochromator, 14... Monochromatic X
Line, 15...Slit, 16...Collimator, 17
... Outgoing X-ray, 18... Sample, 19... Diffraction line,
111... Analyzer, 112... Nuclear emulsion plate, 2
DESCRIPTION OF SYMBOLS 1... Incident X-ray, 22... Sample, 23... Diffraction line, 24... Detector, 25... Diffraction line.

Claims (1)

[Claims] 1. A lattice constant characterized by irradiating a sample to be measured with collimated monochromatic X-rays, diffraction lines from the sample to be measured are separated into angle-resolved spectra, and observed using diffraction microscopy. Measuring method. 2. A monochromator, a collimator on which X-rays of a specific wavelength selected by the monochromator are incident, a sample stage on which a sample to be measured is placed on which the asymmetrically reflected X-rays from the collimator are incident, and a What is claimed is: 1. A lattice constant measuring device comprising at least an analyzer for angle-resolved spectroscopy of diffraction lines.