Modeling of stress-induced leakage current and impact ionization in MOS devices

Stress-induced leakage current (SILC) modeling requires consistency with a variety of experimental observations, like steady-state leakage, transient discharge currents and impact ionization characteristics observed after stress. Here we present a SILC model based on trap-assisted tunneling and recombination at deep-levels in the oxide, which successfully reproduces all SILC features. Based on a detailed analysis of SILC data, a two-band defect distribution is determined, in which the low- and high-energy ranges account for stationary SILC and transient currents, respectively. The stress-induced impact ionization (SIII) components associated with these defect distributions are then calculated, showing that the main contribution results from high-energy states. Simulation results are in good agreement with experimental data for leakage and SIII currents in p-channel devices with an oxide thickness of 8.2 nm. These results point out the limitation of the quantum yield method for measuring the mean energy loss in the SILC mechanism. (C) 2002 Elsevier Science Ltd. All rights reserved.