The Early Stages of Silicide Formation on Metal and Silicon Surfaces, Time-of-Flight Atom-Probe Studies of Atomic Structures and Compositions

ABSTRACTThe early stages of silicide formation on metal and silicon surfaces have been studied in the atom-probe FIM. Precursors to silicide formation are low temperature diffusion of single Si atoms, their interactions, and adsorption layer superstructure formation. These phenomena have been studied quantitatively. At high temperatures, silicide films can be formed. Four distinctive stages of silicide formation on tungsten surfaces have been observed from the atomically resolved FIM images. Formation of silicide layers on platinum, nickel, and silicon surfaces have also been studied. From both the atom-probe compositional depth profiling and the FIM observation one can conclude that the interface formed at low temperature is sharp. At high temperature, Si atoms can diffuse deep into a Pt matrix and Ni atoms into a Si matrix. Conclusions drawn from these atom-probe studies are summarized, and future directions suggested.