Modeling of SILC based on electron and hole tunneling. I. Transient effects

A detailed investigation of the steady-state and transient leakage currents in thin oxides is proposed. The experimental data are compared with numerical results obtained from a model based on an inelastic trap-assisted tunneling process, which includes both electron and hole contributions. In order to accurately reproduce the transient discharge currents, a continuous distribution of oxide traps was adopted. The energies of these levels can be either in correspondence of the conduction or valence band edges of the adjacent silicon/polysilicon layers. Both electrons and holes contribute to the transient stress-induced leakage current (SILC), but the extracted trap densities cannot account for the steady-state SILC. A different mechanism, involving trap levels with energy aligned to the energy gap of the silicon layers is proposed and is developed in the following paper. The model can be applied to any type of device and bias conditions and may be used to correctly recognize the role of electron and hole SILC and the spatial and energy distribution of defect states.