Silicided Ni/Au contacts with very low contact resistance were realized on p-type [001] silicon at low temperature by ex-situ or, alternatively, by in situ annealing processes. During the ex-situ annealing, performed at 200° C for 10 s, a uniformly thin (14 nm) Ni 2Si layer was formed having an extremely flat interface with silicon thanks to the trans-rotational structure of the silicide. During the in situ annealing, promoted by a sputter etch processing (T< 300° C), a 44 nm-thick silicide layer was formed as a mixture of trans-rotational NiSi and epitaxial NiSi2, domains. In both cases, using a low thermal budget has guaranteed a limited consumption of silicon during the reaction process and a good adhesion with the substrate avoiding gold contaminations. As a consequence of the presence of trans-rotational domains, wherein a pseudo-epitaxial relationship between the silicide and the silicon …