Influence of the nature of the Si substrate on nickel silicide formed from thin Ni films

Abstract

We investigate the rate of silicide formation and the composition of the resulting compound when thin (1000–5000 Å) Ni films vacuum deposited onto various substrates are annealed from 200 °C to 325 °C and from 1 2 to 24 h . Only the phase Ni 2Si is observed on substrates of (111), (100) and polycrystalline Si. On amorphous (vacuum-deposited) Si the two phases Ni 2Si and NiSi form simultaneously in two distinct sublayers. In all cases, the compound layers grow at ( time) 1 2 , and the activation energies all lie between 1.3 and 1.6 eV. The actual value of the growth rate depends on the substrate. On (100), polycrystalline and amorphous Si substrates the rates are very similar and correspond to about 1000 Å at 1 h and 275 °C. On (111) Si substrates the rate is about a quarter of that. Transmission electron micrographs establish that silicide layers grown on different substrates have different microcrystalline structure.