Island growth in ion beam assisted metal-on-metal deposition modelled by rate equations

Island growth in ion beam assisted deposition (IBAD) is modelled by rate equations, where deposition, diffusion driven aggregation, defect and target adatom production and island fragmentation are taken into account. It is shown that compared with results obtained for a thermal deposition, deposition with ion bombardment induced island fragmentation causes the total island density to increase and average island size to decrease. The observed behaviour is in qualitative agreement with experimental findings. It is demonstrated how the appropriately scaled island size distributions depend crucially on the fragmentation process, but remain relatively unaffected by diffusion. Possibilities to use scaled distributions in recognizing experimentally the relative importance of different processes in IBAD are pointed out.