Degradation and Breakdown of Gate Oxides in VLSI Devices

A model for the degradation and breakdown of thin gate oxide films is presented. During electrical stresses, a small fraction of the energy of the tunnel electrons that is dissipated in the oxide is converted into the creation of electron traps. When a critical density of traps is achieved, a fast runaway process leads the oxide to break down and its insulating properties are irreversively lost. It is demonstrated that the total charge injected to breakdown depends on the applied current in accordance with recently published results. The quasi-linear log (time-to-breakdown) versus log (current density) plot experimentally obtained for VLSI oxides (tox ≈ 100 Å) is correctly predicted.