Carbon co-implantation for ultra-shallow P+-N junction formation

Carbon co-implantation in silicon has been studied as an approach for achieving ultra-shallow dopant profiles. Carbon implants to a dose of 1×10¹⁴ cm^-2 were performed in conjunction with 2 and 5 keV boron and BF₂ implants. Annealed samples implanted with carbon and boron exhibited junction depths up to 250 A shallower than control samples. However, no change was observed in dopant profiles when BF₂ was used as the implanted species. Residual defect analysis and electrical characterization of boron implanted samples suggest that enhanced carbon levels inhibit defect dissolution mechanisms thereby degrading electrical properties of the junctions. Alternatively, carbon and BF₂ implanted samples exhibit no changes in these parameters from control samples