Radiation Response of MOS Capacitors Containing Fluorinated Oxides

By introducing small amounts of fluorine into the gate oxide, we have been able to significantly alter the radiation response of Metal/SiO2/Si (MOS) capacitors, and their subsequent time dependent behavior. Experimentally we have observed that compared with their control capacitors, which have no fluorine introduced into the oxide, the fluorinated samples exhibit the following major differences: (1) the densities of radiation-induced oxide charge and interface traps are drastically reduced, (2) the gate-size dependence of the radiation-induced interface traps is greatly suppressed, and (3) the overall density of the radiation-induced interface traps continues to decrease with time for many hours after irradiation before a turn-around trend is observed. Possible mechanisms involving the roles that fluorine may play in relieving the oxide strain near the SiO2/Si interface and in the post-irradiation defect-reaction chemistry are discussed.