Hydrogenation Effects On The Hot-Carrier Degradation Of MILC N-Type Poly-Si TFTs

Hydrogenation effects on the performance and hot-carrier (HC) stability of n-type metal induced laterally crystallized (MILC) polycrystalline silicon thin-film transistors (TFTs) are investigated. Performance and stability are systematically investigated using statistics about transfer characteristic. It is demonstrated for the first time that plasma hydrogenation not only largely improves the performance before stress, but also significantly enhances the HC endurance of each parameters of transfer characteristic after stress. The improvement of HC reliability of each parameter about transfer characteristic is attributed to the reduced Si-H bond breaking mechanism, and the suppression of impact ionization in hydrogenated MILC TFTs. But the degradation of hydrogenated TFTs is not improved in output characteristic. And the saturation current of hydrogenated TFT degenerates more seriously. It may be the result of drain induced barrier lowering (DIBL). First high drain voltage (Vd) is applied when we measure the output characteristic. Second local defects near the drain are generated after HC stress in unhydrogenated TFTs, while the defects may be more diffused in hydrogenated TFTs. So DIBL is more effect to unhydrogenated TFTs in output characteristic. As a result, the saturation current of unhydrogenated TFT degenerates more slightly.