Modeling and characterization of dopant redistributions in metal and silicide contacts

A shallow n
⁺
layer of implanted arsenic is used to lower the effective barrier height of PtSi-n-Si and W-n-Si Schottky-barrier diodes. A device model is presented for metal-semiconductor structures that correctly accounts for physical mechanisms involved in the interface formation and dopant redistribution. Image and dipole barrier lowering as well as silicon consumption and dopant pile,up effects present in metal and silicide contacts are included in the model. A theoretical model is presented to calculate the electric-field dependence of metallic charge penetration into the semiconductor energy gap and experimental results are extracted from the measured electrical characteristics of Schottky-barrier diodes. The barrier height and ideality factor are studied at various temperatures and the theoretical calculations are shown to be in good agreement with the experimental results.