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

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.