Stress induced gate–drain leakage current in ultra-thin gate oxide

Ultra-thin gate oxide reliability, in large area MOSFETs, can be monitored by measuring the gate current when the substrate is depleted. When the channel length is scaled down, the tunneling current associated with the source/drain extension region (SDE) to the gate–overlap regions can dominate the gate current. In N-MOSFETs, as a function of the negative gate voltage two components of the gate–drain leakage current should be considered, the first for VFB < VG < 0 V and the second for VG < VFB. These components are studied in this work before and after voltage stresses. The aim of this work is to see whether this gate–drain current can be used to monitor the oxide degradation above or near the source and/or drain extension region in N-MOSFETs. It is important because the most serious circuit-killing breakdown occurs above or near the drain (or source) extension region. Finally, we show that it is necessary, before explaining the gate LVSILC curves obtained after stresses on short-channel devices, to verify which is the dominate current at low voltage.