標題: Role of environmental and annealing conditions on the passivation-free in-Ga-Zn-O TFT
作者: Fuh, Chur-Shyang
Sze, Simon Min
Liu, Po-Tsun
Teng, Li-Feng
Chou, Yi-Teh
電子工程學系及電子研究所
光電工程學系
顯示科技研究所
Department of Electronics Engineering and Institute of Electronics
Department of Photonics
Institute of Display
關鍵字: Thermal annealing;InGaZnO TFT;Annealing environment;Reliability mechanism;Operation model
公開日期: 30-Dec-2011
摘要: We examined the characteristics of passivation-free amorphous In-Ga-Zn-O thin film transistor (a-IGZO TFT) devices under different thermal annealing atmospheres. With annealing at higher temperature, the device performed better at the above-threshold operation region, which indicated the film quality was improved with the decrease of defects in the a-IGZO active region. The mobility, threshold voltage and subthreshold swing of a-IGZO TFT annealed at 450 degrees C was 7.53 cm(2)/V s, 0.71 V and 0.18 V/decade, respectively. It was also observed that the a-IGZO was conductive after thermal annealing in the vacuum, due to the ease of oxygen out-diffusion from the a-IGZO back channel. The oxygen deficiency resultantly appeared, and provided leaky paths causing electrical unreliability when TFT was turned off. In contrast, the annealing atmosphere full of O(2) or N(2) would suppress the oxygen diffusion out of the a-IGZO back channel. The worst Vth degradation of a-IGZO TFT after positive gate bias stress and negative gate bias stress (NGBS) was about 2 V and -2 V, respectively. However, the V(th) shift in the NGBS testing could be suppressed to -0.5 V in vacuum chamber. Material analysis methods including X-ray photoelectron spectroscopy and scanning electron microscopy were used to investigate the change of a-IGZO film after different thermal annealing treatments. The variation of O 1s spectra with different annealing atmospheres showed the consistence with our proposed models. (C) 2011 Elsevier B.V. All rights reserved.
URI: http://dx.doi.org/10.1016/j.tsf.2011.08.088
http://hdl.handle.net/11536/15346
ISSN: 0040-6090
DOI: 10.1016/j.tsf.2011.08.088
期刊: THIN SOLID FILMS
Volume: 520
Issue: 5
起始頁: 1489
結束頁: 1494
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