Determination of the three-dimensional structure of dislocations in silicon by synchrotron white X-ray topography combined with a topo-tomographic technique

Abstract

The determination of the three-dimensional dislocation structure, i.e. the configuration and nature of the dislocations, in silicon by synchrotron white X-ray topography combined with a topo-tomographic technique is demonstrated. A [001]-oriented CZ-Si crystal of diameter approximately 7 mm was fixed on a subsidiary goniometer with three rotation axes (omega, Rx, Ry) and x-y-z stages, keeping its growth axis parallel to the omega-axis. This goniometer was mounted on the swivel stage of the main diffractometer installed at the experimental hutch of beamline BL28B2 of SPring-8. After adjusting the (110) plane to be perpendicular to the incident white X-ray beam by observing transmission Laue patterns, the crystal was inclined by 4.3 degrees so that the 004 Laue spot could be formed by 60 keV X-rays. Laue topographs observed by rotating the omega-axis of the subsidiary goniometer were recorded using X-ray films and a cooled CCD camera. The direction of the dislocation lines, Burgers vectors and glide planes were determined by following the variation in features of the dislocation images in the 004 Laue spot and by examining the contrast of the dislocation images in the Laue spots concerning the [111] and [022] planes. It is concluded that white X-ray topography combined with the omega-rotation technique is useful for clarifying the three-dimensional dislocation structure.

Development of white and monochromatic X‐ray topography system in SAGA‐LS

“…Dash‐necking is usually employed in Si crystal growth technology to remove dislocations that form and propagate in a grown crystal. To understand the mechanism of dislocation elimination in the grown crystal, it is necessary to examine its neck (3–7 mm ϕ ) nondestructively 11, 12.…”

Study of the three-dimensional distribution of defects in crystals by synchrotron radiation diffraction tomography

“…The use of different azimuthal setting or different reflections on projection topographs gave rise to the method of stereo-pairs [6]. More recently, ''topo-tomography'' was shown to produce a 3D image of defects in crystals [7,8]. This approach consists in recording many images in the same Bragg reflection, while turning the sample around the diffraction vector.…”

Characterization of VGFB-grown ZnTe single crystals by means of synchrotron X-ray topo-tomographic technique

“…The technique is very sophisticated but is insufficient for determining the nature of individual dislocations such as their Burgers vectors and glide planes due to a lack of information about the image contrast. Recently, Kawado et al [6] used an improved topotomographic technique, which is white Laue topography combined with the rotation around the diffraction vector, for clarifying the three-dimensional dislocation structure in the Dash necking of Czochralski-grown Si. The advantage of their method is the ability to acquire information about the configuration of lattice defects from the variation in their features observed in a specific Laue spot by the tomographic technique, in addition to information about the image contrast of the defects observed in several Laue spots by conventional white X-ray topography.…”