New global insight in ultrathin oxide reliability using accurate experimental methodology and comprehensive database

Abstract

In this paper, we critically examine several important experimental aspects concerning ultrathin oxide reliability. The statistical nature of breakdown measurements and the impact on data interpretation is discussed. Thickness dependence of Weibull slopes and its impact on reliability projection is reviewed. We also investigate the voltage-dependent voltage acceleration using two independent experimental methods over a wide range of oxide thickness values. Within the framework of a general defect generation model, we explore the possibility of a voltage-dependent defect generation rate to account for the increase in voltage acceleration with decreasing voltages. Using direct experimental results, we clarify that strong temperature dependence found on ultrathin oxides is a voltage effect, not a thickness effect as previously suggested, In the context of voltage-dependent voltage acceleration, we experimentally resolve various seemingly contradicting and confusing observations such as temperature-independent voltage acceleration and non-Arrhenius temperature dependence found on ultrathin oxides. Finally, we provide a global picture for time-to-breakdown in voltage and temperature domain constructed from two important empirical principles based on comprehensive experimental database.