Analysis and modeling of the transient local tunneling in gate oxides

This work presents a detailed investigation of the local transient tunneling currents due to substrate- and gate-near traps generated by Fowler-Nordheim stress in nitrided oxide MOS structures. We demonstrate that for the correct interpretation of the transient stress-induced leakage currents measured in the external circuit, it is essential to include the effects of the substrate and poly-Si capacitances. This leads to gate-voltage-dependent weighting factors, which relate the measured current transients to the local trap tunnel currents near the substrate and the gate. By a combination of these measurements with transient capacitance measurements, it is possible to separately determine the local tunnel currents and, thus, the densities of traps generated close to the substrate and to the gate.