Reduction of contact resistivity by As redistribution during Pd ₂Si formation

We have investigated the redistribution of uniformly doped As atoms (N _D=4.0×10¹⁹ cm^-3) in Si during Pd₂Si formation with neutron activation analysis and the influence of the redistribution on contact resistivity. Some of the uniformly doped As atoms are pushed ahead into Si near the silicide-silicon interface during Pd₂Si formation at 250°C. The amount of the redistributed As atoms increases with the thickness of Si consumed and reaches a peak concentration of 2.0×10²⁰ cm^{- 3}. Contact resistivity is reduced from the initial values of 3.8×10^-5-4.1×10^-4 Ω cm² before silicide formation, to a final value of 1.8×10^-6 Ω cm² after complete reaction. The electrically active As atoms is estimated to be 50% of the total redistributed.