ION-BEAM-INDUCED INTERFACIAL GROWTH IN SI AND SILICIDES

We review the mechanisms and consequences of ion beam-induced epitaxia l crystallization (IBIEC) in the transition metal- or rare earth-impla nted aSi/cSi systems, as determined from in situ transmission electron microscopy (TEM) during irradiation, combined with channeling, high r esolution TEM and optical measurements. IBIEC experiments on nm-size c rystals confirm previously measured low values of interface roughness in IBIEC. We have performed interfacial growth simulations which indic ate that the IBIEC process is, in fact, interface roughness-limited. T hey also suggest that interfacial growth processes are similar in seve ral respects to surface growth processes, and that they largely determ ine (i) the growth habit of silicide precipitation, which is dominated by the interfacial energy, (ii) the possibility of trapping a large f raction of the impurities in non-equilibrium sites, leading to signifi cant supersaturation. A consequence of this effect is to allow incorpo ration of large (over 300-fold supersaturation) Er concentrations in t he substitutional sites of the Si lattice, leading to room-temperature photoluminescence (without any oxygen co-implantation). Evidence of a new, thermally induced instability in interfacial growth is presented : it displays both intermittency and very high growth rates, and is st rongly affected by ion irradiation.