Improvement of the Thermal Stability of NiSi by Germanium Ion Implantation

Abstract

The thermal stability of nickel monosilicide (NiSi) is one of the important research topics in the area of nano-complementary metal oxide semiconductor. This paper reports the effect of germanium (Ge) ion implantation on the thermal stability of the NiSi/Si structure. High dose Ge ion implantation (>5x10(15) cm(-2)) can improve the thermal stability of the NiSi/Si structure. Ge ion implantation before NiSi formation results in a very smooth NiSi/Si interface due to Ge atom pileup at the NiSi/Si interface. This high concentration Ge layer reduces the interface energy so that the thermal stability can be improved. Both the phase-transformation temperature and agglomeration temperature are improved by 50-100 degrees C. The effects of Ge ion implantation on the NiSi-contacted n(+)-p and p(+)-n shallow junctions are also examined. Although fast Ni diffusion via the ion implantation induced defects is observed, better thermal stability can still be observed on the n(+)-p junction.