Implant temperature dependence of transient-enhanced diffusion in silicon (100) implanted with low-energy arsenic ions

The diffusion of arsenic implanted into silicon at low ion energies (2.5 ke V) has been studied with medium-energy ion scattering, secondary ion mass s pectrometry and four-point probe measurements. The dopant redistribution to gether with the corresponding damage recovery and electrical activation pro duced by high-temperature (550-975 degreesC) rapid thermal anneals has been investigated for a range of substrate temperatures (+ 25, + 300 and -120 d egreesC) during implant. Initial results show an implant temperature depend ence of the damage structure and arsenic lattice position prior to anneal. Solid-phase epitaxial regrowth was observed following 550 degreesC, 10s ann eals for all implant temperatures and resulted in approximately 60% of the implanted arsenic moving to substitutional positions. Annealing at 875 degr eesC resulted in similar arsenic redistribution for all implant temperature s. Following annealing at 925 degreesC, transient-enhanced diffusion was ob served in all samples with more rapid diffusion in the + 25 degreesC sample s than either the -120 or + 300 degreesC implants, which had similar dopant profiles. In the 975 degreesC anneal range, similar rates of implant redis tribution were observed for the + 300 and + 25 degreesC implants, while dif fusion in the -120 degreesC sample was reduced. These observations are disc ussed qualitatively in terms of the nature and density of the complex defec ts existing in the as-implanted samples. (C) 2000 Elsevier Science Ltd. All rights reserved.