Passivation of poly-Si thin film transistors with ion-implanted deuterium

A comparison of ion-implanted deuterium and ion implanted hydrogen for passivation of grain boundary states in poly-Si thin film transistors (TFTs) is presented for the first time. Gate-drain bias stressing was carried out after anneals at 350 degrees C, 400 degrees C, and 450 degrees C. Under stress, deuterated TFTs are more resistant to bias stress than hydrogenated TFTs in terms of most PMOS performance parameters and NMOS leakage current, but are markedly less resistant to NMOS threshold degradation. While still showing promise, these results are not as impressive as those shown for hot carrier degradation in very large scale integration (VLSI) MOS devices. After 350 degrees C activation anneal, deuterium is less effective than hydrogen at initial device passivation, probably as a result of excessive implant damage. After anneals at 400 or 450 degrees C, deuterium becomes more effective at passivation than hydrogen, possibly due to differences in diffusion between hydrogen and deuterium.