Nickel silicide is formed on the basis of a gaseous precursor, such as nickel tetra carbonyl, wherein the equilibrium of the decomposition of this gas may be controlled to obtain a highly selective nickel silicide formation rate. Moreover, any etch step for removing excess nickel may be avoided, since only minute amounts of nickel may form on exposed surfaces, which may then be effectively removed by correspondingly shifting the equilibrium. Consequently, reduced process complexity, enhanced controllability and enhanced tool lifetime may be obtained.