This paper investigates the effects of Zr capping on nickel silicided n(+)/p shallow junctions. Although nickel silicide possesses many benefits compared with titanium and cobalt silicide, some potential problems still need to be addressed for ultrashallow junction applications. In this work, a Zr protective cap is used to preserve the silicide from oxygen contamination and to suppress the increase of junction leakage during the silicidation process. Due to the suppressed leakage current and the appropriate series resistence, formation of a 30 nm ultrashallow junction can be accomplished. (C) 2005 The Electrochemical Society.