Influence of hydrogen plasma surface treatment of Si substrate on nickel silicide formation

Nickel silicide (NiSi) offers the advantages of lower processing temperature, reduced silicon consumption in silicide formation, and absence of bridging failures and is hence expected to replace Ti and Co silicides as contact material in Si microelectronics. In this article, we report on our work involving the study of hydrogen plasma pretreatment of the Si substrate on the properties of subsequently formed NiSi. We observe the sheet resistance of the silicide film to decrease with hydrogenation at the expected lower processing temperatures of 400 and 500 °C. Transmission electron microscopy studies do reveal that defects are introduced near the silicide-silicon interface in the hydrogenated wafers at lower processing temperatures. But these defects are annealed out at higher processing temperatures. Secondary ion mass spectroscopy profiles show an enhanced diffusion of Ni into the Si substrate at 500 and 600 °C, apparently due to the defects introduced in the substrate by the hydrogen treatment.