Issues of ultra shallow junction formation using sub-1 keV ion implantation

We examined the issues of ultra shallow junction formation using sub-1 keV ion implantation including the SIMS profiling, the contamination from the low energy implant, the channeling tail and the B diffusion. It is important to know how the SIMS profile closes to the actual profile, Recently, profiles deeper than 15 nm can be studied using SIMS on the condition for the shallow junction. A deceleration system is employed to reduce the practical beam current, so the energy-contamination from the deceleration must be considered. The penetrating contaminant makes one vary the junction depth depending on the beam line pressure and beam trajectory. Because the low energy beam can be spread easily compared with the conventional energy beam, the parts of the beam line should be protected from hitting the beam. The B profile of sub-1 keV ion implantation has different schemes from the conventional energy implantation, for example, the amount of channeling tail becomes small. Also, the B diffusion is influenced from the implant damage and B clustering. Therefore the dose and energy should be optimized carefully. Also, the improvement of annealing methods has a potential to achieve low resistivity shallow junctions