Role of Nitrogen Incorporation into Hf-Based High-k Gate Dielectrics for Termination of Local Current Leakage Paths

摘要

We studied effects of nitrogen incorporation into Hf-based high-k gate dielectrics on local insulating properties by conductive atomic force microscopy. Nitrogen-incorporated HfSiO/HfO_2/SiO_2 gate stacks exhibited excellent dielectric reliability, whereas we observed the creation of local leakage sites for untreated gate stacks, i.e., without nitridation. Both types of high-k dielectric layers were crystallized, and there was no relationship between the current leakage sites and surface morphology. These findings indicate that grain boundaries of the high-k films do not act as the leakage sites. Instead, we propose nitrogen incorporation as an important method for terminating the current leakage paths and discuss detailed mechanisms based on first-principles calculations.