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Bilayers of Si/metal (metal on top) and metal/Si (Si on top) were annealed in vacuum to produce the Si/silicide/metal and metal/silicide/Si configurations, respectively. The sandwich structures were then irradiated with Xe ions of energies ranging from 125 to 300 keV such that the Xe ions traverse only one of the two interfaces (metal-silicide or silicide-Si). In the case of CrSi2, irradiation above 150°C induces further and laterally uniform growth of a stoichiometric layer of silicide, but only when the Cr/CrSi2 interface is traversed, not when the other interface is traversed. We conclude that the formation of CrSi2 is an interface-limited process, which is consistent with the linear time dependence of the growth of CrSi2 under thermal annealing, and that the limiting reaction occurs at the Cr/ CrSi2 interface. On the other hand, in TaSi2 for temperatures up to 500°C, and in Pt2Si at room temperature, Xe ions penetrating through only one of either of the two interfaces does not induce silicide growth in a layer-by-layer fashion. This observation is consistent with the fact that under thermal annealing, the growth of Pt2Si is a diffusion-controlled process. The absence of further growth of TaSi2 is attributed to unidentified processes which control the formation of the silicide.
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