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Abstract: Ultra-shallow junction formation in metal oxide semiconductor field effect transistor (MOSFET) fabrication has been one of the most controversial parts of the silicon process technology. In the present work, ab initio calculations of the atomic and electronic structures of crystalline silicon (c-Si) with X@B6 and X@B12 (X=H–Br) clusters have been performed to investigate carrier generation by doping atoms inside the cage of the boron clusters as a novel type dopants for shallow junction formation. We confirmed that octahedral B6, cubo-octahedral B12 (B12-co), and icosahedral B12 (B12-ico) clusters can exist stably in c-Si and should act as double acceptors. We also found that H atoms can be settled in B12-co cluster and the H@B12-co cluster can introduce a very shallow single acceptor level whose activation energy is lower than those of B6, B12 (-co, -ico), and substitutional boron atom (Bs). The structural stability of the clusters was discussed from the viewpoint of the covalency between atom X and surrounding boron atoms using the bond overlap population and of the charge distribution, and we found that, in c-Si, the three-center bonding is not enough to account for their stability of the boron clusters. Among 96 trial models, H@B12-co cluster is the most promising candidate as the cluster dopant for the formation of a high-performance, ultra-shallow junction. [Copyright &y& Elsevier]

The electronic structure and x-ray photoelectron spectra of silicon with octahedral B6 clusters are investigated using first-principles calculations. It is found that the B6 clusters act as double acceptors in silicon and that the simulated chemical shift of the B 1s orbital signals of the B6 clusters in x-ray photoelectron spectra coincides with the chemical shift of B 1s experimentally observed in as-implanted silicon at an extremely high dose of boron. These results reveal that the B6 clusters are the origin of hole carriers. We propose a mechanism of hole generation and a model of B6 cluster formation at implantation-induced divacancy sites. [ABSTRACT FROM AUTHOR]