The impact of hydrogen on negative bias temperature instability in atomic layer deposited HfO2-based hole channel field-effect transistors is investigated. After forming gas anneal of the devices at high temperature (580degreesC), the saturated threshold voltage shift of the transistor is about 100 mV at 125degreesC. The threshold voltage instability is reduced to about a factor of 2 for devices annealed in forming gas at 520degreesC. A detailed analysis of the experimental results suggests that the defects responsible for negative bias temperature instabilities are hydrogen-induced overcoordinated oxygen centers, due to the transport and trapping of protons in the gate dielectric stack. (C) 2004 American Institute of Physics.