Composition profiles and Schottky barrier heights of silicides formed in NiPt alloy films

Abstract

Metal silicides such as PtSi and NiSi have important applications in silicon integrated circuit technology as rectifying or Ohmic contacts. With a view to obtaining contacts with Schottky barrier heights adjustable between those of NiSi and PtSi, silicides were formed in NiPt alloy films with varying concentrations of Ni and Pt. The metal films were sputter deposited sequentially from Ni and Pt targets and also from a single alloy target containing 15 wt% Pt. Silicides were formed by sintering at 475 °C for 20 min. The depth-compositional profiles of these films were obtained by Auger electron spectroscopy (AES) coupled with Ar+ ion sputtering. The effects of the sintering and the presence of oxygen impurity on the composition profiles are discussed. The chemical effects observed in the Auger spectra from the silicides are presented. The Schottky barrier height (φB) of the silicide film on n-type silicon increases from that of NiSi-nSi to PtSi-nSi with increasing amount of Pt in the NiPt films. The variation of φB cannot be adequately explained by the interfacial composition obtained from the Auger data.