Spectroscopic characterization of stress-induced leakage current in sub 5-nm-thick silicon oxide film

Abstract

This article proposes a spectroscopic characterization technique for examining the stress-induced leakage current in sub 5-nm-thick silicon oxide films. The fluctuation power of stress-induced leakage currents suggests that defects have a single, dominant energy level. Monte Carlo simulations are carried out to verify the defect model and stress-induced leakage current characteristics. It is clearly demonstrated using simulations and spectroscopic analyses that the stress-dependent magnitude of the leakage current is characterized by defect location and defect energy level. Defect distribution is extracted from stress-induced leakage current characteristics based on a physics-based practical defect model; the defect distribution differs from past predictions. It is also identified from simulations that defect regions, which contribute to the stress-induced leakage current observed at high gate voltages, exist mainly at a depth of about 1.2 nm from the SiO2/Si substrate interface with the distribution width of 0.6 nm. Finally, simulations suggest that the stress-induced leakage current observed at low gate voltages results from structural modification of the gate electrode/SiO2 interface.