Cluster size effect on reactive sputtering by fluorine cluster impact using molecular dynamics simulation

The mechanism of high-yield sputtering induced by reactive cluster impact w as investigated using molecular dynamics (MD) simulations. Various sizes of fluorine clusters were radiated on clean silicon surface. At an incident e nergy of 1 eV/atom. F atom and F-2 molecule are only adsorbed on the surfac e and sputtering of Si atom does not occur. However, fluorine cluster. whic h consists of more than several tens molecules causes sputtering. In this c ase, most of Si atoms are sputtered as fluorinated material such as SiFx. T his effect is due to the fact that cluster impact induces high-density part icle and energy deposition, which enhances both formation of precursors and desorption of etching products. The deposition of atoms and energy becomes denser as the incident cluster size increases, so that larger clusters hav e shown higher sputtering yield. (C) 2001 Elsevier Science B.V. All rights reserved.