H-2 and NH3 plasma passivation on poly-Si TFTs with bottom-sub-gate induced electrical junctions

Abstract

The effects of NH3 and H-2 plasma passivation on the characteristics of poly-Si thin-film transistors (TFTs) with source/drain extensions induced by a bottom sub-gate were studied. Our results show that although significant improvements in device performance can be obtained by either passivation method, the NH3-plasma-treatment appears to be more effective in reducing the off-state leakage, subthreshold swing, and in improving mobility compared to H-2 plasma passivation. Furthermore, NH3 plasma treatment is also found to be more effective in reducing the anomalous subthreshold hump phenomenon observed in nonplasma-treated short-channel devices. Detailed analysis suggests that all these improvements can be explained by the more effective passivation of traps distributed in both the front and back sides of the channel by NH3 plasma treatment. (C) 2003 The Electrochemical Society.