SHALLOW JUNCTION FORMATION BY SMALL CLUSTER IMPLANTATION

摘要

We have studied the cluster ion implantation with different small cluster ions to form ultra-shallow junctions for the future CMOS technology. Shallow junctions were formed by GeB, SiB, and SiB_2 cluster ions implantation into Si at different energies and dosages. Two-step annealing was performed to separate crystal regrowth and point defects removal from dopant activation and diffusion. Samples were rapid thermal annealed in dry N_2 at (ⅰ) 1000℃/10sec (one step annealing), (ⅱ) 550℃/300sec, and (ⅲ)550℃/300sec +1000℃/10sec (two-step annealing) respectively. For samples prepared by GeB ion implantation, the two step-annealing produced a junction depth that was only one half of what the one-step annealing could achieve. The samples were also evaluated by transmission electron microscopy, RBS(Rutherford Backscattering Spectrometry)/channeling and SIMS (Secondary Ion Mass Spectrometry) profiling. The two-step annealing procedure led to a defect free recrystalized region with Ge atoms mostly in the substitutional sites. The SiB and SiB_2 cluster ions also led to similar results, though less effective in reducing the junction depth.