Infusion doping for USJ formation

Abstract

We report for the first time results on infusion doping of boron for ultra shallow junctions (USJ). Using B/sub 2/H/sub 6/ or BF/sub 3/ source gas, the resulting USJ boron dopant profile measured by SIMS shows no evidence of channeling with extreme abruptness of <2.5nm/decade for a 12 nm shallow junction. Infusion doping shows a power log to the 1/3 relationship between energy to junction depth in contrast to the traditional linear fit observed with ion implantation due to nuclear stopping power effects. Boron surface doping levels of 1-2E22/cm/sup 3/ for 2E16/cm/sup 2/ doses were achieved. Dopant activation using low temperature furnace annealing from 450/spl deg/C to 950/spl deg/C were compared using standard 4PP and non-penetrating elastic material 4PP for sheet resistance measurements,on these USJ structures. Also, electrically active dopant profiling was conducted using spreading resistance profile (SRP) for USJ junction depth (Xj) comparison to SIMS. Use of amorphizing implantation resulted in lower Rs values after low temperature SPE annealing.