Area Dependence of Reliability Characteristics for Atomic Layer Deposition HfO2 Film under Static and Dynamic Stress

Abstract

The reliability characteristics of high-k gate stacks of HfO2 films using atomic layer deposition method have been investigated. Weibull slopes (β), area scaling factor, and lifetime projection model have been checked for static and dynamic stress, in order to further understanding of the breakdown mechanism of HfO2 gate stacks. Irrespective of the static and dynamic stress, the breakdown distributions of HfO2 capacitors with various areas can be merged to a single Weibull plot, suggesting that the dielectric breakdown is intrinsic for both cases. This study shows that a higher frequency and lower duty cycle in the bipolar stress resulted in a longer lifetime enhancement. Additionally, increasing the stress time and voltage of the opposite polarity in the bipolar stress enhanced the dielectric breakdown lifetimes as well. With respect to gate area effect, the amount of lifetime enhancement increases as the gate area decreases. A higher weibull slope is observed on a smaller gate area under dynamic stress.