Improvement of Hafnium Oxide/Silicon Oxide Gate Dielectric Stack Quality by High Pressure D₂O Post Deposition Annealing

In this study, an improvement of device performance with high-pressure heavy water (D2O) vapor annealing in a hafnium oxide/silicon oxide gate dielectric stack is reported in comparison with dry and water vapor annealing. The injected heavy water vapors reduced the interface state density and bulk oxide traps in hafnium oxide without increasing the equivalent oxide thickness. Under low electrical field stress, this method showed the smallest flat band voltage shift due to the effective removal of pre-existing traps in the HfO2 layer. These significant improvements of the electrical properties can be explained by the different thermal desorption rate between deuterium and hydrogen.