Stress-induced leakage current due to charging damage: gate oxide thickness and gate poly-Si etching condition dependence

Abstract

Stress-induced gate leakage current (SILC) was used to evaluate plasma process-induced damage to ultra-thin gate oxide transistors. Even though the leakage currents increase as the oxide thickness decreases, the reliability of ultra-thin gate oxide (2.2 nm) is superior to the thicker oxides. No SILC was observed for the thinnest films, while thicker oxides show large SILC variation due to process-induced charging damage. The effect of different gate poly-Si etching processes in a high density TCP (transformer-coupled plasma) system were also evaluated. Only the gate that was etched with an abnormally high bias power overetch process, and connected to large connection ratio antenna shows SILC.