Time-dependent dielectric breakdown of SiO₂ films in a wide electric field range

We have performed time dependent dielectric breakdown measurement of SiO₂ films in the electric field (E_OX) range 7-13.5 MV/cm and evaluated the electric field dependence of intrinsic lifetime, using both area and temperature dependences of oxide lifetime. We have evaluated the electric field dependence of time to breakdown (t_BD) below 125 °C, because the activation energy of intrinsic lifetime changes at 125 °C t_BD of 7.1 and 9.6 nm oxides is not proportional to exp(E_OX) but proportional to exp(1/E_OX). This suggests that the breakdown mechanism of 9.6 and 7.1 nm oxides is the same and adheres to the anode hole injection model. However, the breakdown mechanism of 4.0 nm oxides is not the same as that of 7.1 and 9.6 nm oxides. The slope of log(t_BD) versus 1/E_OX plot in 4.0 nm oxide increases with decreasing oxide fields. The intrinsic lifetime in the positive gate bias decreases with increasing oxide thicknesses in the range of electric fields employed in the present experiment.