Characterization of SiO/sub 2/ dielectric breakdown for reliability simulation

The authors analyze breakdown distributions of thin oxide MOS capacitors to reveal the limitations of accelerated procedures for reliability simulation at circuit level. The detailed analysis of the breakdown distributions corresponding to different stress voltages shows the presence of three modes of breakdown, associated with different kinds of defects. These breakdown nodes control the shape of the distributions at different oxide field ranges. The mean values of time-to-breakdown, charge-to-breakdown, and energy-to-breakdown and their dependence on oxide field are found to be directly related to the mode dominating the distribution. Since the shape of the breakdown distribution changes with stress voltage, an accelerated testing procedure must provide a way to extrapolate to operation conditions not only the mean value, but also the shape of the distribution. The results indicate that different physical mechanisms cause the breakdown at low and high fields.>