New global insight in ultra-thin oxide reliability using accurate experimental methodology and theoretical modeling

Abstract

We critically examine several important aspects concerning ultra-thin oxide reliability. Time- or charge-to-breakdown (T/sub BD//Q/sub BD/) measurements with high statistical accuracy are carried out over a wide range of oxide thickness (T/sub ox/), voltages, temperatures, and test structures. Thickness dependence of Weibull slopes and its physical interpretation based on a simple analytic model are reviewed. We also investigate the voltage-dependent voltage acceleration using two independent experimental methods of long-term module stress and area scaling techniques. In the context of voltage-dependent voltage acceleration, we resolve various seemingly contradicting and confusing observations such as the strong temperature dependence of oxide breakdown observed on ultra-thin oxides, temperature-independent voltage acceleration at a fixed T/sub BD/, and non-Arrhenius temperature dependence found on ultra-thin oxides. Using a newly developed kinetic approach for oxide breakdown, we propose a two-step hydrogen model as an alternative to explain the experimental observations on voltage-dependent voltage acceleration and temperature dependence of oxide breakdown.