Influence of Au as an impurity in Ni-silicide growth

Abstract
The growth of Ni silicides in Ni films on Si and in lateral diffusion couples with Ni films on Si patterns on Al2O3 is strongly influenced by the presence of 1–2 at. % Au in Ni. During silicide formation, Au accumulates at the silicide/ Ni and silicide/Si interface and retards phase formation at temperatures below the Au/Si eutectic. At temperatures of 400–500 °C (above the eutectic), the growth rate is enhanced by over two orders of magnitude. We believe the increase is due to the segregation of Au at the Ni-silicide grain boundaries and the transport of Si in the Au-Si liquid. The growth rate is independent of temperature from 600–800 °C and is limited by the diffusion of Si in the Au-Si liquid at a value of 10−5 cm2/sec.