Fabrication of ultra-shallow junctions with high electrical activation by excimer laser annealing

The combination of BF2 ion implantation and excimer laser annealing has been used to fabricate ultra-shallow junctions, with depths below 100 nm and high electrical activation. Secondary ion mass spectrometry and spreading resistance profiling analysis have been performed to investigate B atomic transport and electrical activation in these samples. The structural analysis of the material irradiated by excimer laser and of the corresponding samples annealed by conventional methods, was carried out by Transmission Electron Microscopy. The latter technique enabled us to detect the presence of microcavities, induced by the implanted fluorine, which are detrimental with respect to the electrical activation issue. We have found that the use of ion implantation and excimer laser annealing results in ultrashallow junctions with an electrically active peak concentration higher than the levels normally achieved by conventional annealing cycles.