Two topography experimental stations are presently available at SPring-8. The first, constructed at the short-length bending magnet beam line BL28, is designed to perform white- and selected wide-energy-range x-ray topography. The other is a high-resolution diffraction topography station located on the medium-length bending magnet beam line BL20, where the incoming beam displays a large cross section and high degree of parallelism. This allows us to observe fine structures of three-dimensionally large crystals used in industry if high energy is employed. The construction concepts, as well as first, selected experimental results are presented.

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.

We developed a compact synchrotron X-ray topography system equipped with a demountable Si channel-cut crystal monochromator with an energy range of 5-20 keV at beamline 09A in SAGA Light Source (SAGA-LS) to enable switching between a white X-ray beam and a monochromatic X-ray beam. The position of incidence of the X-ray beam on the sample is kept constant because the beam-path difference, which is caused by inserting the monochromator and by tuning the X-ray energy, is adjusted automatically. Two possible applications of this system are proposed: (1) the observation of dislocations in a thick Si rod by white X-ray topography, and (2) a comparative study of X-ray images of defects and strain in a 4H-SiC wafer captured using white and monochromatic X-ray beams.

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We have studied the propagation and elimination of dislocations generated at the early stage of Czochralski silicon crystal growth using synchrotron white x-ray topography combined with a topo-tomographic technique. Two silicon crystals with [001] growth-axes were examined. One was intentionally grown without enlarging its diameter to easily observe the features of the dislocation propagation, and the other was grown with Dash necking, followed by a 2 inch enlargement of its diameter in order to observe the elimination of the dislocations. The three-dimensional structure of the individual dislocation, i.e. the direction of the dislocation line, its Burgers vector and the glide plane, were determined. These investigations revealed that dislocation half loops, which were generated from tangled dislocations, were expanded on their glide planes and were often deformed by their interaction, cross slip and collision with the crystal surface, followed by a gradual decrease in their density. The dislocation-elimination effect of the Dash necking was caused by the expansion of the dislocation half loops being terminated within the crystal and by their pinning on the crystal surface.

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We have observed dislocations in a CZ‐silicon crystal using step‐scanning white X‐ray section topography and examined the feature of the dislocation images reconstructed by stacking 200 shots of sec‐ tion topographs. These topographs were obtained from symmetric 004‐reflection in the Laue case using 20, 30, and 60 keV X‐rays. Direct images, intermediary images, and dynamical images of dislocations were observed in a tomogram, i.e., a sliced image obtained from the stacked section topographs, and the contrast of the dynamical images was reduced with increasing X‐ray energy. The stacked section topographs provided three‐dimensional images of the dislocations based on the direct images, and the sliced image enabled us to observe the dislocations separately in a highly dislocated region of the CZ‐silicon crystal. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

An electron beam induced current (EBIC) method using an Al-Si Schottky barrier has been developed and applied to the observation of oxidation-induced stacking faults in (001) silicon. The minority carriers in thermally-oxidized silicon have a very large diffusion length. Analysis of the Y-modulation image of a stacking fault is effective for correlating the EBIC image contrast with the induced-current variation. Increasing beam energy increases the depth of a Frank partial dislocation segment showing the maximum contrast. A deep dislocation segment shows a larger resolution than a shallow one, and a further increase in resolution results from an increase in the beam energy. The Schottky barrier method is applied to the evaluation of the electrical activity of stacking faults and to the examination of their annealing behavior.