JPH04218753A - Total reflection x-ray diffraction microscopic apparatus - Google Patents

Abstract

PURPOSE:To observe the crystal flaw in the vicinity of the surface of a sample, in allowing selected X-rays to be incident to the sample at an incident angle equal to or less than a critical angle generating total reflection, by shortening the wavelength of a monochrometer. CONSTITUTION:When the wavelength of X-rays 15 made monochromatic by a monochrometer 14 is slightly shortened by setting the omega rotation of a first goniometer 13 to a low angle, the angle thetabeta of diffraction from an asymmetric reflecting surface is slightly reduced so as to follow the shortening of the wavelength of X-rays 15 and, therefore, by performing the omega rotation of a second goniometer 17 at a low angle, the diffracted wave from a sample is obtained. As a result, the incident angle thetabeta-alpha of the X-rays made monochromatic incident to the sample 18 is reduced and, when this work is repeated, the incident angle thetabeta-alpha can be allowed to approach 0 without missing the asymmetric reflection from the sample 18 and, finally, a critical angle generating total reflection can be reduced. By this method, the diffracted wave from the sample can be microscopically observed under such a condition that the incident angle thetabeta-alpha is set to the critical angle or less by a photographic film 19.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a surface-sensitive total reflection X-ray diffraction microscopy device for detecting minute crystal defects on a surface.

(Prior Art) Crystal defects (eg, vacancies, dislocations, stacking faults, precipitation, segregation, etc.) existing in a single crystal have a negative effect on semiconductor device characteristics. Conventionally, there is an X-ray diffraction microscopy method that uses the X-ray diffraction phenomenon shown in Figure 2 to observe the pattern of the spatial distribution of crystal defects within a single crystal (Reference: Applied Physics 196
7, 36, 88-104). The incident X-rays 21 are formed by a monochromator 22 into wide X-rays 23 that are monochromatic and have small angular divergence, and then enter a sample 24, and the diffracted X-rays 25 from the sample 24 are captured by a photographic film 26. By photographing, crystal defects are observed using diffraction microscopy.

(Problem to be solved by the invention) However, in the conventional method, the penetration depth of X-rays into the sample is large, approximately several μm, and only average information in the depth direction can be obtained, and surface polarization The drawback is that it is impossible to obtain information about crystal defects only in the vicinity.

The object of the present invention is to eliminate such conventional drawbacks and provide an apparatus for observing crystal defects in the very vicinity of the surface using X-ray diffraction microscopy.

(Means for Solving the Problem) The present invention maintains the condition that the diffracted X-rays from the sample are asymmetrically reflected by making monochromatic X-rays incident on the sample using a monochromator and performing ω rotation of the sample. At the same time, by shortening the wavelength selected by the monochromator by ω rotation of the monochromator, the angle of incidence of the incident X-rays on the sample is set to a state below the critical angle at which X-rays undergo total reflection, and the diffracted X-rays from the sample are The present invention provides a total internal reflection X-ray diffraction microscopy apparatus characterized by observing radiation using a diffraction microscopy method.

The present invention also provides an X-ray source that generates X-rays of continuous wavelengths;
A monochromator for monochromating the X-rays generated from the X-ray source, a sample stage arranged to irradiate the sample with the monochromatic X-rays by the monochromator, and diffraction generated from the sample by the X-ray irradiation. The present invention provides a total internal reflection X-ray diffraction microscopy apparatus comprising means for observing X-rays, and wherein the monochromator and the sample stage are rotatable by ω.

(Function) The relationship between the sample and the incident X-rays is arranged to satisfy the conditions for asymmetric reflection in order to reduce the incident angle of the X-rays. The incident X-rays are monochromated by an X-ray monochromator with continuous wavelengths. At this time, if the ω rotation of the monochromator is rotated to a low angle, the wavelength of the obtained X-rays becomes shorter. Following this change in wavelength, the sample is also rotated by ω so that conditions for asymmetric reflection are always maintained. If the wavelength of the incident X-ray is further shortened in a state where this asymmetric reflection is obtained, diffracted X-rays can be obtained from the sample at an incident angle other than the critical angle at which total internal reflection occurs. As a result, the penetration depth of X-rays into the sample can be made significantly shallower than in the past, making it possible to obtain information very close to the sample surface.

(Example) Synchrotron radiation has a powerful continuous wavelength and is very useful as an X-ray source for detecting crystal defects using a diffraction phenomenon. 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 a total internal reflection X-ray diffraction microscopy apparatus according to the present invention. In FIG. 1, reference numeral 11 indicates synchrotron radiation light, which is continuous light. After this synchrotron radiation light 11 is formed into an X-ray beam size by a slit 12, it is monochromated to a specific wavelength by a monochromator 14 installed in the head of a first goniometer 13 that is rotatable in ω-2θ. . After the monochromated X-rays 15 are formed into a beam size by a slit 16, a second goniometer 17 which is rotatable in ω-2θ
The light is incident on the sample 18 installed in the head of the camera. The reflection from the sample 18 is asymmetrical so as to reduce the incident angle θβ−α of the monochromated X-rays 15 incident on the sample 18 using asymmetric reflection that utilizes lattice planes that are oblique to the sample surface. Choose a reflective surface. Here, θβ is the monochromator 14
is the diffraction angle of the monochromatic X-ray 15 caused by the asymmetric reflecting surface of the sample 18, and α is the angle formed by the sample surface and the asymmetric reflecting surface.

Now, the X-ray 15 has been made monochromatic by the monochromator 14.
By rotating the ω rotation of the first goniometer 13 to a lower angle, the wavelength of It is possible to obtain the diffraction line from the sample 18 by rotating it at a low angle. As a result, monochromatic X-rays 15 incident on the sample 18
The incident angle θβ−α decreases, and by repeating this process, the incident angle θβ−α decreases without losing sight of the asymmetric reflection from the sample 18.
It is possible to bring β-α close to 0, and finally to make it smaller than the critical angle at which total internal reflection occurs. The wavelength of the monochromated X-rays 15 can be continuously shortened by the monochromator 14 by effectively utilizing the continuity of synchrotron radiation light. Diffraction lines from the sample 18 are observed microscopically using a photographic film 19 under the condition that the incident angle θβ−α is below the critical angle.

In the above embodiments, a synchrotron radiation source was used as the X-ray source because it can easily provide powerful continuous wavelength X-rays. The effect of the present invention is that the continuous wavelength
For example, a normal X-ray sealed tube may be used as long as it can obtain radiation. Further, in the embodiment, a goniometer capable of ω-2θ rotation was used in the apparatus, but any goniometer capable of ω rotation may be used.

(Effects of the Invention) According to the present invention, diffracted X-rays can be obtained by injecting X-rays into the sample at an incident angle below the critical angle that causes total internal reflection, so crystal defects existing in the extremely close vicinity of several nm from the surface, e.g. , swirls, strained layers due to surface treatment, scratches, dislocations, etc. can be observed using X-ray microscopy. It can be used as an effective means for comparing these crystal defects and deterioration of semiconductor device characteristics.

[Brief explanation of the drawing]

FIG. 1 is a block diagram according to the present invention, and FIG. 2 is a block diagram showing a conventional X-ray diffraction microscopy apparatus. 11... Synchrotron radiation, 12... Slit, 13...
1st goniometer, 14... Monochromator, 15... Monochromated X-ray, 16... Slit, 17... Second goniometer, 18... Sample, 19... Photographic film, 20... Synchrotron radiation light source, 21... Incident X-ray, 22... Monochromator, 23... X-ray, 24... Sample, 25... Diffracted X-ray, 26...
photographic film. Representative Patent Attorney Susumu Uchihara

Claims (2)

[Claims] [Claim 1] Injecting monochromatic X-rays into a sample by a monochromator, and performing ω rotation of the sample, while maintaining a condition in which the diffracted X-rays from the sample are asymmetrically reflected. By doing this, the wavelength of the incident X-rays is shortened and the angle of incidence of the incident X-rays on the sample is below the critical angle at which the X-rays undergo total internal reflection. A total reflection X-ray diffraction microscopy device characterized by observation. 2. An X-ray source that generates X-rays of continuous wavelength; a monochromator for monochromating the X-rays generated by the X-ray source; comprising a sample stage arranged for irradiation and means for observing diffracted X-rays generated from the sample by X-ray irradiation,
A total internal reflection X-ray diffraction microscopy apparatus characterized in that the monochromator and the sample stage are rotatable by ω.