NANOSCALE OBSERVATION OF A GRAIN-BOUNDARY RELATED GROWTH MODE IN THIN-FILM REACTIONS

We report the atomic scale observation of a thin film growth mode rela ted to grain boundaries in multilayers of polycrystalline gold and amo rphous silicon. Using differential scanning calorimetry, in situ x-ray diffraction, and high-resolution electron microscopy, we observe sili cide nucleation to take place at grain boundaries in the polycrystalli ne gold films followed by lateral silicide growth parallel to gold/sil icon interfaces. This growth mode is related to solid-state reactions at low temperatures where atomic transport is restricted to grain and interphase boundaries. It demonstrates the importance of thin film mic rostructure for phase selection during thin film reactions at low temp eratures.