Effects of channel width and NH3 plasma passivation on electrical characteristics of polysilicon thin-film transistors by pattern-dependent metal-induced lateral crystallization

Abstract

This work studied the effects of channel width and NH3 plasma passivation on the electrical characteristics of a series of pattern-dependent metal-induced lateral crystallization (PDMILC) polysilicon thin-film transistors (poly-Si TFTs). The performance of PDMILC TFTs improves as each channel width decreasing. Further, PDMILC TFTs with NH3 plasma passivation outperforms without such passivation, resulting from the effective hydrogen passivation of the grain-boundary dangling bonds, and the pile-up of nitrogen at the SiO2/poly-Si interface. In particular, the electrical characteristics of a nanoscale TFT with ten 67 nm wide split channels (M10) are superior to those of other TFTs. The former includes a higher field effect mobility of 84.63 cm(2)/V s, a higher ON/OFF current ratio (> 10(6)), a steeper subthreshold slope (SS) of 230 mV/decade, and an absence of drain-induced barrier lowering (DIBL). These findings originate from the fact that the active channels of the M10 TFT have exhibit the most poly-Si grain enhanced to reduce the grain boundary defects and the best NH3 plasma passivation. Both effects can reduce the number of defects at grain boundaries of poly-Si in active regions for high performances. (c) 2005 The Electrochemical Society. All rights reserved.