The effect of high pressure (HP) H-2/D-2 annealing and subsequent N-2 annealing, to enhance reliability, on hafnium-based high-k metal oxide semiconductor field effect transistor (MOSFET) has been studied. HP hydrogen annealing effectively passivates dangling bonds which in turn reduce the interface state density. Additional annealing in nitrogen ambient reduces threshold voltage shifts (Delta V-th) due to bias temperature instability and hot carrier injection. This improvement due to subsequent annealing might be related with the annihilation of hydrogen-related trapping sites from the high-k bulk. Since charge trapping is attributed mainly to dangling bonds at the interface and excess hydrogen species in the bulk of the high-k oxide, by optimizing annealing conditions, both reliability and performance of high-k MOSFETs are improved. (c) 2006 The Electrochemical Society.