Improved stacked-structure oxide by laser annealing

Laser annealing techniques were successfully incorporated into standard MOS processing to improve the quality of oxides grown over polycrystalline silicon (polysilicon). Polysilicon films (5000 Å thick) deposited over 1000 Å SiO2, grown over (100) bulk Si were exposed to a short pulse (20 nsec) of ruby laser radiation at an energy density of 1 J/cm2 and subsequently oxidized at 925 °C. The resulting oxides over the polysilicon were found to have leakage currents which are lower by over three orders of magnitude than oxides grown over polysilicon films which were not laser annealed. C-V measurements taken on the underlying polysilicon-SiO2-Si structure indicate that no deleterious effects were produced in the underlying structure by the laser radiation.