Stress enhanced arsenic diffusion in titanium salicided junctions by implantation into C49 TiSi{sub}2 and rapid thermal annealing

摘要

We studied reverse leakage current in n+/p titanium-salicided shallow junctions using C49 Ti-suicide as a diffusion source. After Ti deposition, rapid thermal annealing (RTA) was performed to form the C49 Ti-suicide. Subsequently, arsenic ionswere implanted and a 2nd RTA was carried out at 850°C to form the low resistivity C54 Ti-silicide. In spite of no drive-in process following the 2nd annealing, the implanted As diffused well into Si substrate and the reverse leakage current of the n+/pjunctions was reduced to two orders of magnitude lower. Since the high chemical affinity of As to Ti-silicide trapped the dopant in the silicide, it has been known that Ti or Ti-silicide cannot be used as a diffusion source. However, in this work, wefound that the C49 Ti-silicide acted as a diffusion source of As ions. The reason of fast diffusivity is attributed to the generation of high tensile stress induced by As implantation.