Unified model for breakdown in thin and ultrathin gate oxides (12-5 nm)

A unified model explaining the wear-out and the breakdown of thin and ultra thin films of silicon dioxide when subjected to electrical stressing is pro posed. The suggested breakdown model is based on the ability of charge trap ped inside the dielectric to increase locally the effective dielectric perm ittivity (epsilon) of the material by increasing the polarization locally. The impact of this local perturbation to the macroscopic characteristics of the oxide is investigated. Breakdown is correlated with the existence of a fixed amount of trapped charge inside the oxide. Moreover, the dependence of this bulk oxide trapped charge at breakdown with respect to the oxide th ickness has been justified by the suggested mechanism and has been found to have excellent agreement with the experimental data. (C) 1999 American Ins titute of Physics. [S0021-8979(99)08421-2].