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

In this article, a modified generalized trap-assisted tunneling model (GTAT ) is proposed to explain the excessive currents occurring at low electric f ields during stressing (stress-induced leakage current, SILC). Parameters s uch as trap energy level, Gaussian-distributed traps, and energy loss (when electrons tunnel through an oxide) are all included in this model. The tra p energy levels relative to the effective Fowler-Nordheim tunneling barrier s (Phi (B)) are classified into either shallow traps or deep traps. Quantit ative 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 curr ent-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 ra nge of 10(18)-10(20) cm(-3) depending on various stress conditions. The ene rgy level of induced traps and trap concentration can be easily derived fro m this model without the need for other complicated measurements. This mode l is demonstrated to be an accurate and reliable SILC model for investigati ng ultrathin gate oxide devices in integrated circuits of future generation s. (C) 2001 American Institute of Physics.