A novel transient current technique to characterize process-induced thin oxide damage

Thin oxide characterization is becoming more involved due to the secondary effects like oxide leakage and narrow active regions in small-geometry devices. In-line monitoring techniques should also be sensitive to gate oxide degradation with the subsequent steps of an advanced CMOS multilevel metal process. In this work, we use transient current measurements (I/sub G/-V/sub G/) to investigate process-induced defects in MOS capacitors with thin oxides. We demonstrate high sensitivity and simplicity of the measurement, as well as a novel approach to data analysis. In the literature, transient currents such as stress-induced leakage SILC and displacement current, have been attributed to oxide defects: either in the oxide volume (slow trapping), or near the interface (fast trapping). No correlation between these currents has been reported so far. Using specially designed structures, we observed for the first time that fast or slow trapping may occur either in common or exclusively, and that depending on the V/sub G/ range, either the SILC or the displacement component would dominate. Mechanisms are discussed.