High-dose implantations of Al into Si(111) and Si(100)

摘要

High dose implants of Al (0.5 (times) 10(sup 18) to 2.0 (times) 10(sup 18)/cm(sup 2)) at 200 keV into silicon substrates at 375C were performed in an attempt to form a pure, monocrystalline buried layer of Al in silicon upon post-implant annealing. Nuclear reaction analysis (NRA) and Auger electron spectroscopy (AES) were used to determine the Al concentration and morphology as a function of depth. Results show a peak Al concentration of 83 at.% at a depth of (approx)350 run for the highest dose, and the morphology of the Al is of an interconnected network of 100 at.% Al. Failure to form a continuous elemental layer is explained by the as-implanted morphology resulting thermally induced precipitate coarsening rate at 375C. Formation of large, stable, individual Al precipitates was thermodynamically favored for the implant conditions and effectively precluded coalescence into a continuous layer.