Epitaxial NiSi₂ formation by pulsed ion beam annealing

Epitaxial nickel silicide layers have been formed by ion beam annealing of 300-400-Å Ni films on (001) Si with 300-400-ns pulses of H+ or Ba+ ions. Cellular structures were formed at an H+ energy density of 1.3 J/cm2 and a Ba+ energy density above about 0.7 J/cm2. At lower energy densities, uniform epitaxial layers of NiSi2 were formed, as indicated by both Rutherford backscattering channeling and transmission electron microscopy. With ion beam annealing, melting starts at the Ni/Si interface and epitaxy is found at energy densities well below that required to melt crystalline Si.