Dopant Redistribution from Ion Implanted WSi2 on Poly-Si

The possibility of doping the polycrystalline silicon in a polycide configuration by implantation into the silicide and subsequent thermal diffusion has been evaluated. In a first step it is demonstrated that a phosphorus implantation to a dose of 5E15 cm^-2 into WSi2 can produce flatband voltages similar to those obtained by conventional diffusion doping into the polysilicon. This is true even if 2E15 cm^¿2 boron is subsequently implanted. Secondly arsenic and boron implantations were tried with the aim to produce n-and p-doped gates respectively. Work function shifts between the two species approaching 1 Vindicate that typical source/drain implantations may be used for this purpose.