Simulation of stress-induced leakage current in silicon dioxides: A modified trap-assisted tunneling model considering Gaussian-distributed traps and electron energy loss

In this article, a modified generalized trap-assisted tunneling model (GTAT) is proposed to explain the excessive currents occurring at low electric fields during stressing (stress-induced leakage current, SILC). Parameters such as trap energy level, Gaussian-distributed traps, and energy loss (when electrons tunnel through an oxide) are all included in this model. The trap energy levels relative to the effective Fowler-Nordheim tunneling barriers (Φ_B) are classified into either shallow traps or deep traps. Quantitative analyses of the effects of oxide thickness, trap energy levels, trap concentrations, and energy losses on SILC are performed. Examples relating to the SILC of thermal oxides are shown to validate the suitability of our GTAT model. Good agreement between experimental data and the simulated current-voltage curves using this model is obtained for various SILC phenomena. The extracted trap energy levels exist between 1.5 and 2.0 eV for shallow traps and at 3.2 eV for deep traps, while trap concentrations are in the range of 10¹⁸-10²⁰cm^-3 depending on various stress conditions. The energy level of induced traps and trap concentration can be easily derived from this model without the need for other complicated measurements. This model is demonstrated to be an accurate and reliable SILC model for investigating ultrathin gate oxide devices in integrated circuits of future generations.