Effects of the presence of native silicon oxide at the Fe/Si interface on the formation of silicides studied by Auger spectroscopy

Abstract

Auger lineshape analysis on SiLVV and FeLMM transitions was used to investigate the mechanisms of iron mono- and disilicide formation at the Fe/Si interface in the absence and in the presence of a native oxide layer (SiOx) approximately 0.5 nm thick on the silicon surface. Fe films, 0.3 to 2 nm thick, were evaporated on Si(111) and on SiOx/Si(111) surfaces in UHV environment. Thereafter thermal treatments up to 580°C were performed in situ. Besides the well known mechanism of silicide formation via silicon diffusion at the Fe/Si interface, it was demonstrated that silicide formation in the presence of native oxide is inhibited at room temperature while, at T≥450°C, it occurs at the SiOx/Si interface via Fe diffusion through the oxide layer. This ends in a Fe/SiOx/FeSi/Si or Fe/SiOx/FeSi2/Si type of structure. The kinetics of silicide formation in the presence of an oxide layer are therefore dominated by the diffusion of the metal through the oxide. © 1993.