Annealing process influence and dopant-silicide interaction in self-aligned NiSi technology

This paper reports the annealing process influence on interfacial electrical properties, dopant effects on silicide formation, and dopant redistribution during silicidation in self-aligned NiSi technology. The reverse leakage current results of NiSi/n-Si Schottky diodes show that two-step rapid thermal process (RTP) significantly improves the NiSi/Si area-contact characteristics in comparison with one-step RTP, and low temperature in RTPI is beneficial to the final Ni-silicide/Si contact properties. Both structural and electrical characterization shows substantially different Ni-silicidation behaviors on heavily-doped n and p Si substrates at low temperature (300°C). The larger grain size of Ni₂Si formed on heavily As-doped Si is responsible for the lower resistivity, comparing with Ni:Si formed on heavily B-doped Si. Ni/Si reaction on highly doped Si substrates also results in significant dopant segregation at the silicide/Si interface and pile up in void-layer formed just underneath the silicide surface.