Développements d'une technique de topographie en réflexion des rayons X

An X-ray reflexion topography camera has been designed to study structural defects near the surface of monocrystalline semiconductors. Large surfaces can be covered by means of successive fixed exposures. A surface of 30 mm x 10 mm for example can be studied in less than ten minutes on nuclear emulsions. The conditions for the observations of dislocations in gallium arsenide have been examined: the choice of reflecting planes is limited by the depth of penetration of X-rays, so that the effective crystal thickness must be of the order of the width of a dislocation image (2-5 microns). Studies to which these observations can be applied are numerous: structural defects induced by diffusion, lattice strains, orientation of dislocations near the surface, structural evolution of silicon during integrated circuits elaboration, structure of cleavage surfaces, lapping and polishing defects, structural defects of epitaxic layers.