Structural characterization of damage in Si(100) produced by MeV Si+ ion implantation and annealing

Abstract

Buried amorphous layers were produced by implantation of MeV Si+ ions in silicon single crystal at room temperature and liquid nitrogen temperature. The damage is characterized structurally both in the as-implanted condition and after post-implantation furnace annealing. Growth of the amorphous layer during room temperature implantation is found to occur by a layer-by-layer mechanism with relatively sharp interfacial transition regions. A wide region ahead of the buried amorphous region extending to the surface is observed to be free of any extended defects. Recrystallization of the damaged region during thermal annealing occurs by solid-phase epitaxial growth at both interfaces. A lower growth velocity is found at the upper interface, which is attributed to a higher hairpin dislocation density grown-in at this interface. Results of irradiation at liquid nitrogen temperature, on the other hand, show that nucleation and growth of the amorphous damage occurs over a wide region and is not confined to the interfacial region. This results in a very diffuse upper interface composed of a mixture of amorphous and crystalline phases. Substantial reordering is observed in this mixed-phase region after 400°C annealing, even though this temperature is too low for normal interfacial solid-phase epitaxial growth. Cross-sectional transmission electron microscopy, as well as Rutherford backscattering spectroscopy, were used in this study.