Improvement of TDDB reliability, characteristics of HfO_2 high-k/metal gate MOSFET device with oxygen post deposition annealing

摘要

In this work, influences of oxygen effect on an Hf-based high-k gate dielectric were investigated. A post deposition annealing (PDA) including oxygen ion after high-k dielectric deposition was used to improve reliability of the Hf-based high-k/metal gate device. The basic electrical characteristics of devices were compared with and without the PDA process. Experiment results show that the oxygen PDA did not degrade the drive current and effective oxide thickness of the Hf-based gate devices. In addition, reliability issues such as positive bias instability, negative bias instability and TDDB were also improved by the oxygen PDA significantly. During the TDDB test, the charge trapping was characterized by an in situ charge pumping system, which could make us to understand the variations of interface trap during the reliability stress easily.