Ultra-shallow junction formation : co-implantation and rapid thermal annealing
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Boron diffusion and activation in the presence of co-implanted species are studied experimentally and theoretically (ab initio Molecular Dynamics simulations and SUPREM diffusion process simulator) in this dissertation. Simulation results imply that B diffusion and activation in the presence of coimplanted species can be affected through both the electronic and strain compensation effects and the theoretical prediction is consistent with experimental data. In the presence of co-implanted species, the electronic bonding between B and the co-implant species makes it energetically unfavorable for B to migrate when it comes close to the co-implant species. The bonding can be characterized by the electronegativity difference between B and the coimplanted species. The strain effect, on the other hand, indicates that B tends to stay close to the larger co-implant species (In, for example) so that the strain caused by the size misfit of In and Si can be compensated by the smaller B atom. In order to have both the above factors be effective in B diffusion reduction, we need to increase the concentration of the co-implant species in order to maximize the B diffusion reduction with the co-implant technique. Experiments on B diffusion and activation in the presence of Al, Ga, In, Ge, F and C, with or without capping layers (oxide, nitride or Si), are conducted in this research. Those species are incorporated into Si either by ion implantation or Chemical Vapor Deposition (CVD) process. Boron and co-implant diffusion and activation is studied Rapid Thermal Annealing (RTA) for various process parameters such as ramp-up rate, soak time and peak temperature. Fundamental studies on the interaction of B, defects and the co-implanted species are also included in this dissertation.