Modeling of boron implantation into Si with decaborane ions

A molecular Dynamics (MD) model of B implantation into Si and of sputtering the Si surface with energetic B₁₀ clusters has been developed. The goal was to simulate the implantation of ions of decaborane (B₁₀H₁₄), which may become an important process for the formation of ultra shallow junctions in future MOS devices. The simulations, carried out for the cluster ion impact energy from 3.5 kev to 15 keV, have revealed the formation of a large amorphized region in a subsurface region. At low cluster impact energies in this range some of the B atoms were recoiled back from the surface, but at the energy of 12 kev and above almost all of the Boron atoms were successfully implanted into Si. The sputtering yield of Si has been also computed and found to increase with energy, reaching the value of 6 Si atoms per B₁₀ cluster at 15 KeV. The number of displaced surface atoms correlates well with the sputtering yield, and between 3.5 and 10 kev it has a non-linear dependence on energy. At higher energies the number of displaced atoms increases linearly with energy, in agreement with the Khinchin-Pease formula [9]. The sputtering yield at 12 kev was also measured by the amount of Si removed by a decaborane beam from a thin Si film deposited on a carbon substrate. The predicted sputtering yield agrees well with this experiment.