Pre- and post-BD electrical conduction of stressed HfO2/SiO2 MOS gate stacks observed at the nanoscale

In this work, the electrical properties of fresh and stressed HfO₂/SiO₂ gate stacks have been studied using a prototype of Conductive Atomic Force Microscope with enhanced electrical performance (ECAFM). The nanometer resolution of the technique and the extended current dynamic range of the ECAFM has allowed to separately investigate the effect of the electrical stress on the SiO₂ and the HfO₂ layer of the high-k gate stack. In particular, we have investigated this effect on both layers when the structures where subjected to low and high field stresses.