Multilevel Contact System with a Thin Silicide Reaction Controlling Interlayer

Abstract

ABSTRACTTaking advantage of controllable interdiffusion and reaction processes by using a 50 nm thin Ti interlayer an annealing step in the temperature range from 450 to 475°C transforms the TiNiAg layer sequence on silicon into a stable final state, whereby a contamination free, homogeneous nanoscale NiSi contact layer arises with low values of the contact resistance. Intercalating a thin Ti layer the nickel silicide growth rate is lowered by 2 orders of magnitude. Low sheet resistance and a good bondability are preserved by the remaining Ni-Ag top layer sequence which does not interact during the contact formation process.