Structural and electrical characterization of silicided Ni/Au contacts formed at low temperature (<300°C) on p-type [001] silicon

Abstract

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 NiSi 2, 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 lattices is established, an ohmic behavior was observed in a wide range of substrate doping (3.5 10 18 3 10 19 B/cm 3) for both annealing processes (in situ and ex-situ). On the other hand, conventional TiNiAu and CrNiAu contacts showed, in the same range of B doping concentration, a rectifying behavior with systematically higher specific contact resistance values (R c) compared to those of the Ni silicided contacts. © 2011 American Institute of Physics.