AVS 45th International Symposium
    Surface Science Division Thursday Sessions
       Session SS-ThP

Paper SS-ThP9
The Atomistics of Silicide Formation on Si(111) and Si(113) Studied with High Temperature STM

Thursday, November 5, 1998, 5:30 pm, Room Hall A

Session: Surface Science Division Poster Session
Presenter: V. Dorna, Ruhr-Universitaet Bochum, Germany
Authors: V. Dorna, Ruhr-Universitaet Bochum, Germany
P. Kohstall, Ruhr-Universitaet Bochum, Germany
U.K. Koehler, Ruhr-Universitaet Bochum, Germany
Correspondent: Click to Email
Basic steps of the nucleation of iron silicide on Si(111) and Si(113) during gas phase deposition (CVD) were investigated by high temperature STM directly during growth up to 650°C. The formation of ordered silicides above 300°C is directly observed in form of STM-"movies". When solely iron is deposited via Fe(CO)@sub 5@ as a gaseous source, silicon from the substrate reacts to form the silicide. On Si(111) always three different types of islands nucleate even in the very first stage. The dominating @gamma@-silicide type is surrounded by holes in the silicon substrate. In a quantitative analysis the stochiometry of the silicide nuclei was found to be temperature dependent, whereas the sticking behavior of the precursor gas is not activated. At higher temperatures the fraction of a second island-type increases, which shows an only weakly ordered surface periodicity pointing to an @alpha@-silicide. A reversible transition between both phases can be forced by a surplus of Si or Fe. The third island type is implanted into the substrate surface. When Fe and Si using Si@sub 2@H@sub 6@ are co-deposited, a gas composition for a stochiometric silicide growth is found which is in agreement with separately determined sticking coefficients on the substrate. With increasing coverage all different phases transform into @gamma@-silicide, but no layer by layer growth could be archived on Si(111). On Si(113), on the other hand, the 3D-growth seems to be suppressed in the case of the co-depostion, which may be a chance to achieve layer by layer growth.