Diffusion of nickel in silicon below 475 °C

Abstract

Nickel films were deposited on (100) and (111) surfaces of single-crystal silicon and were then annealed. The conditions under which the nickel is deposited determine whether or not an NiSi compound forms on annealing. It is postulated that defects are necessary for the formation of an NiSi compound at annealing temperatures below at least 475 °C, although the presence of defects may not necessarily cause the formation of a silicide. For substrate temperatures below 70 °C, defects are created during the vapor deposition of nickel on silicon. These defects always result in the formation of nickel silicide when the sample is annealed at higher temperatures. When nickel is deposited on defect-free silicon at temperatures of about 250 °C no defects are generated and, although interdiffusion of nickel and silicon occurs, silicide formation does not take place upon subsequent annealing below 475 °C. The activation energies for the diffusion of nickel into (100) silicon and (111) silicon were determined.