Role of hydrogen on negative bias temperature instability in HfO2-based hole channel field-effect transistors

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 (580°C), the saturated threshold voltage shift of the transistor is about 100mV at 125°C. The threshold voltage instability is reduced to about a factor of 2 for devices annealed in forming gas at 520°C. 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.