Impact of Post-Metal Deposition Annealing Temperature on Performance and Reliability of High-K Metal-Gate N-Finfets

This research studies the effects of post-metal deposition annealing temperature on degradation induced by positive bias stress (PBS) in TiN/HfO2 n-channel fin field-effect transistors (FinFETs). The initial electrical characteristics possess higher threshold voltage, transconductance and on-state current in high-annealing temperature devices. In addition, PBS-induced degradation was found to be more severe in high-annealing temperature devices due to more high-k bulk traps. However, in these devices, oxygen vacancies are generated within HfO2 since oxygen is more likely to diffuse toward the interface layer (IL) and repair Si/SiO2 dangling bonds. Furthermore, using charge-pumping and C–V measurements, less interface trapping and a thicker IL were found in high-annealing temperature devices, verifying the proposed model.