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Millisecond annealing techniques with flash lamps or lasers have become increasingly common for activating dopants and eliminating implantation-induced damage after ion implantation for transistor junction formation in silicon. Empirical data show that such techniques confer significant benefits, but key physical mechanisms underlying these benefits are not well understood. The present work employs numerical simulation and analytical modeling to show that for boron, millisecond annealing reduces unwanted dopant spreading by greatly reducing the time for diffusion, which more than compensates for an increased concentration of Si interstitials that promote dopant spreading. Millisecond annealing also favorably alters the relative balance of boron interstitial sequestration by the crystal lattice vs interstitial clusters, which leads to improved electrical activation at depths just short of the junction. [ABSTRACT FROM AUTHOR]

The article focuses on a model with a representation of defect annihilation at surfaces and near-surface band bending with improved representation of interstitial clustering in developing suitable annealing strategies. It provides a background on the rise of annealing methods after ion implantation that span a vast array of time scales given stringent scaling requirements on transistor junction depth and dopant activation. The experimental methods are discussed which employed data for the diffusion and activation of implanted boron in two time regimes.

In this letter, we present direct and unambiguous experimental evidence for nonthermal illumination effects in boron or arsenic implanted silicon. Both, dopant diffusion and activation vary significantly with illumination. Depending on annealing temperature, diffusion is either enhanced or inhibited. The results have significant implications for modeling and formation of ultrashallow junctions. [ABSTRACT FROM AUTHOR]

The continual downscaling of silicon devices for integrated circuits requires the formation of pn junctions that are progressively shallower, incorporate increasing levels of electrically active dopant, and sustain minimal implantation damage. In the case of boron implanted into preamorphized Si, the authors show that all these goals can be accomplished simultaneously through the use of an atomically clean surface, which during annealing acts as a large sink that removes Si interstitials selectively over dopant interstitials. [ABSTRACT FROM AUTHOR]

Abstract: Molecular dynamics simulations reveal a new picture for diffusion dynamics on the surface of amorphous silicon. The primary transport mechanism differs substantially from that observed on crystalline surfaces, in which small numbers of highly mobile adatoms or vacancies form and subsequently diffuse over substantial distances. Instead, diffusion takes place via large numbers of single atoms or dimers that move roughly one atomic diameter and are associated with highly strained rings having four atoms. [Copyright &y& Elsevier]