Nickel silicide is being considered as a candidate for applications in deep sub-micron integrated circuits. In this paper, some pertinent electrical and material properties are studied systematically. The effects of substrate doping on the silicide sheet resistance are examined for both single crystal and poly-silicon substrates. The thermal stability of the silicide films and the effects of dopants are discussed. Particular attention is paid to these properties as the silicide feature size is reduced towards the 0.1 mu m range, The influence of feature size on the morphology and topography of the silicide is also presented.