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Impact of Annealing on Contact Formation and Stability of IGZO TFTs

2014; Institute of Physics; Volume: 61; Issue: 4 Linguagem: Inglês

10.1149/06104.0405ecst

2151-2051

Tarun Mudgal, Nathaniel Walsh, Robert G. Manley, Karl D. Hirschman,

Nanowire Synthesis and Applications

Annealing processes were investigated on Indium-Gallium-Zinc-Oxide (IGZO) thin-film transistors (TFTs). Molybdenum and aluminum were used as contact metals which defined the working source/drain electrodes. Annealing was performed either pre-metal or post-metal deposition, in various gas ambients including air, oxygen, nitrogen, forming gas (5% H 2 in N 2 ) and vacuum. Pre-metal annealing in air ambient resulted in similar I-V characteristics on Mo-contact and Al-contact devices. A post-metal anneal for Mo-contact devices resulted in higher on-state current and steeper subthreshold slope, whereas the Al-contact devices experienced severe degradation suggesting the formation of an AlO x interface layer. A post-metal anneal at 400 °C in N 2 followed by an air ambient ramp-down yielded Mo-contact devices with SS ~ 200 mV/dec, channel mobility µ sat ~ 8.5 cm 2 /V∙s, and improved stability over other anneal conditions.