High resolution studies of NiSi₂ ultrathin film formation by ion scattering and cross-section tem

Abstract

Ultrathin epitaxial NiSi2 films (0-40 Å) have been grown on Si(111) surfaces. Medium energy ion shadowing and blocking has been used to determine the orientation, morphology and interfacial order of these films. For the whole coverage range studied ((0-1) × 1016 Ni atoms cm2) the films are found to be rotated 180° about the surface normal with respect to the Si(111) substrate. Using the high depth resolution of the technique the annealed films are shown to consist initially of islands, which coalesce into continuous films for coverages above ≈ 5 × 1015 Ni atoms cm2. High resolution cross-section transmission electron microscopy shows the NiSi2Si interface to be atomically abrupt. This interface has been probed directly using the ion channeling technique, and the number of disordered Ni atoms at the interface is found to be less than 7.5 × 1013 atoms cm2. © 1985.