Phosphorus diffusion in isoconcentration backgrounds under inert conditions in silicon

The diffusivity of phosphorus in isoconcentration backgrounds under inert conditions in silicon is investigated. Phosphorus is implanted at low dose into silicon wafers that are constantly doped with arsenic and boron. These samples are annealed to remove any damage. Secondary ion mass spectroscopy (SIMS) measurements are taken of these as-implanted samples. The wafers are then diffused at both 900 and 1100 “C for 60 and 30 min, respectively. The wafer profiles are then measured using SIMS. The ditfusivity of phosphorus is measured for five different dopant concentrations. The results show that a double-negative interstitial component of phosphorus is needed to adequately model the data. Also, the heavily doped boron sample shows a significantly retarded diffusivity at 1100 “C! which suggests phosphorus-boron pairing or significant strain effects on diffusion.