ELECTRON-MICROSCOPY STUDY OF OXIDATION-INDUCED DEFECTS AT THE SILICON SILICON-DIOXIDE INTERFACE

It is shown by transmission and electron scanning microscopies and energy-dispersive X-ray spectroscopy that the conditions of thermal annealing and the initial surface damage influence the microstructure of the silicon-silicon-dioxide interface and the silicon underlayers, especially the structure and chemical composition of defects. Annealing underr vacuum enhances the dislocation formation induced by diamond polishing. Oxidizing annealing of similar samples induces stacking faults, while mechanochemically polished samples do not show any stacking faults after the same thermal treatment. Copper precipitation in {110} planes is observed. The shape of the precipitates depends on the density of nucleation sites in the near-surface layers as well as on the amount of contaminating copper: some small copper precipitates are detected when the silicon has been mechanically polished and oxidized, while giant copper colonies are revealed when the silicon sample has been mechanochemically etched.