Effects of hydrogenation on the performance and hot-carrier endurance of polysilicon thin-film transistors

Statistical analysis was performed to investigate the performance and reliability of hydrogenated polysilicon thin-film transistors (TFTs) in relation to the hydrogenation process. The hydrogenation was performed in pure H/sub 2/ plasma and in plasma of 4% H/sub 2/ diluted in Ar or He gas. TFTs hydrogenated in H/sub 2//Ar or H/sub 2//He plasma have lower on-voltage and better uniformity compared to the nonhydrogenated devices due to passivation of grain boundary dangling bonds. Hot-carrier experiments demonstrate that electron trapping is the dominant mechanism at the early stages of the degradation process and generation of interface and grain boundary traps as the stress proceeds further. The overall results indicate that devices hydrogenated in H/sub 2//He plasma are the most reliable in terms of uniformity and hot-carrier stress.