Experimental study of gate voltage scaling for TDDB under direct tunneling regime

Systematic experiments of time-to-breakdown (T_BD) of thin gate oxides are carried out in this paper for quantitative understanding of gate voltage scaling for TDDB under the direct tunneling regime. It is found that the slope of ln T_BD has a nonlinear relationship to gate oxide voltage, V_ox, and thus, the conventional constant voltage acceleration model is not applicable for lifetime prediction. A simple model to explain the experimental voltage acceleration factor is proposed based on the anode hole injection (AHI) concept. It is shown that the significant decrease in hole generation due to lowering of the electron energy injected to the anode greatly helps the TDDB reliability