ION-BEAM-ASSISTED GROWTH OF BETA-FESI2

This article reports the structural and morphological characterization of beta-FeSi2 films, about 120 nm thick, grown by ion beam assisted deposition (IBAD). The silicide layers were obtained by Fe evaporations onto (001) Si substrates maintained at T=600-degrees-C, while an Ar+ beam bombarded the sample surface at an energy ranging between 100 and 650 eV. Beta-FeSi2 films were even grown at several ion current densities and, in one case, the beam bombardment was limited to the early stage of the silicide formation. We have found that MAD process reduces the crystalline grain size and improves the film morphology. Moreover, the relationship between ion beam process and grain nucleation at the silicide/silicon interface shows that when the number of Ar+ reaching the silicide/Si interface is about 1/3 of the Si substrate surface atomic density, the nucleation mechanism tends to saturate.