Thermal stability of Ni–Pt–Ta alloy silicides on epi-Si1−xCx

We investigated the silicide formation in Ni/epi-Si1−xCx systems. Ni–Pt and Ni–Pt–Ta films were deposited on epi-Si1−xCx/Si substrates by DC magnetron sputtering and processed at various temperatures. The sheet resistance of the silicide from the Ni alloy/epi-Si1−xCx systems was maintained at low values compared to that from Ni/Si systems. By TEM and EDS analyses, we confirmed the presence of a Pt alloy layer at the top of the Ni–silicide layer. The stability of the silicide layer in the Ni alloy/epi-Si1−xCx system is explained by not only the Pt rich layer on the top of the Ni–silicide layer, but also by the presence of a small amount of Pt in the Ni–silicide layer or at the grain boundaries. And both the thermal stability and the morphology of silicide were greatly improved by the addition of Ta in Ni–Pt films.