Effective work function modulation (È m,eff ) and the thermal/electrical stability of NiSi fully-silicided (FUSI) gates on SiO 2 and HfO 2 are investigated. A new method, implant-to-silicide, differing from the pre-doped method, is used to realize È m,eff adjustments. The È m,eff of NiSi FUSI gates on SiO 2 can be tuned by incorporating BF 2 þ or P þ dopants after silicidation. Nevertheless, the Fermi-pinning effect was observed in the NiSi/HfO 2 gate which limits the È m,eff adjustment. A thin SiO 2 interfacial layer can reduce the Fermi-pinning effect. A NiSi FUSI gate on SiO 2 is thermally stable up to 600 C. The thermal stress and impurity diffusion after a prolonged 600 C annealing degraded the oxide integration. The temperature of the post-silicidation process should be as low as possible to lessen the thermal stress and impurity diffusion.