Dopant-Segregated Schottky Junction Tuning With Fluorine Pre-Silicidation Ion Implant

Dopant-segregated Schottky (DSS) junctions are formed by implant-to-silicide (ITS) processing with NiSi. It is shown that a fluorine pre-silicidation ion implant (F-PSII) can be used to reduce the depth of the doped Si region. This provides a new means for engineering the source/drain extension regions in DSS source/drain MOSFETs for performance optimization. It is also shown that there are two distinct regions of diffusion that can result in a kink in the dopant profile for long post-ITS anneals. F-PSII also reduces DSS diode leakage by reducing the extent of Ni diffusion into Si, which reduces the concentration of generation-recombination centers. Finally, F-PSII reduces the electron Schottky barrier height (SBH) in DSS junctions despite a reduction in interfacial dopant concentration apparently due to the reduction in Ni spatial distribution. The majority-carrier SBH is found to be zero or near-zero for DSS junctions formed by ITS processing, with or without F-PSII.