A two-step process of Ni silicide formed on bulk silicon,and the effects of different process conditions,including two-step RTA temperature and time,selective etching,and process protective nitrogen gas on the properties of the Ni silicide film have been studied.In particular,the experiments show that the quality of NiSi film is very sensitive to the process conditions of the first RTA.The experiments also show that the quality of the film is very sensitive to the flow of protective nitrogen gas.The corresponding mechanisms are discussed. A two-step process of Ni silicide formed on bulk silicon, and the effects of different process conditions, including two-step RTA temperature and time, selective etching, and process protective nitrogen gas on the properties of the Ni silicide film have been studied. In particular, the experiments show that the quality of NiSi film is very sensitive to the process conditions of the first RTA. The experiments also show that the quality of the film is very sensitive to the flow of protective nitrogen gas. The corresponding mechanisms are discussed .