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

Abstract

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.