Formation of NiSi-Silicided p+n Shallow Junctions by BF2+ Implantation into/through Silicide and Rapid Thermal Annealing

Abstract

NiSi-silicided p+n shallow junctions are fabricated by BF2+ implantation into/through a thin NiSi silicide layer, followed by rapid thermal annealing (RTA). The NiSi film starts to show agglomeration after RTA at 650°C, which may result in the formation of discontinuous islands at higher temperatures. The incorporation of fluorine atoms in the NiSi film can retard the film agglomeration, making the film stable up to 800°C. A forward ideality factor very close to unity and a reverse bias current density of 0.6 nA/cm2 can be attained for the NiSi(31 nm)/p+n junctions fabricated by BF2+ implantation to a dose of 5×1015 cm-2 at 35 keV, followed by RTA for 30 s at 650°C; the junction formed is about 37 nm measured from the NiSi/Si interface. Activation energy measurement shows that the reverse bias junction currents are dominated by the diffusion current, which indicates that most of the implanted damage can be recovered by RTA at temperatures as low as 650°C.