Synthesis of NiSi2 by 6 MeV Ni implantation into silicon

Abstract

Six MeV high-dose Ni implantation into silicon has been applied to synthesize deep-buried metallic layers. These layers have been analyzed by optical reflectivity and spreading resistance depth profiling as well as transmission electron microscopy and cross-section transmission electron microscopy. Already in the as-implanted state, at target temperatures of 450 K and doses above 1017 Ni/cm2, epitaxial precipitates of NiSi2 are formed. They grow in type-A and type-B orientations. In addition to these polyhedral crystallites, thin NiSi2 platelets on {111} lattice planes exist. At a dose of 1.3 × 1018 Ni/cm2, a continuous but highly defective layer of epitaxial NiSi2 is formed by coalescence of mainly type-A precipitates at the maximum of the Ni profile. Investigations indicate that damage gettering of nickel atoms as well as the atomic density increase during implantation influence the depth distribution of implanted metal atoms. Moreover, a suppression of silicon amorphization by nickel is evident.