High-Performance Low-Cost Back-Channel-Etch Amorphous Gallium–Indium–Zinc Oxide Thin-Film Transistors by Curing and Passivation of the Damaged Back Channel

Abstract

High-performance, low-cost amorphous gallium-indium-zinc oxide (a-GIZO) thin-film-transistor (TFT) technology is required for the next generation of active-matrix organic light-emitting diodes. A back-channel-etch structure is the most appropriate device structure for high-performance, low-cost a-GIZO TFT technology. However, channel damage due to source/drain etching and passivation-layer deposition has been a critical issue. To solve this problem, the present work focuses on overall back-channel processes, such as back-channel N2O plasma treatment, SiOx passivation deposition, and final thermal annealing. This work has revealed the dependence of a-GIZO TFT characteristics on the N2O plasma radio-frequency (RF) power and frequency, the SiH4 flow rate in the SiOx deposition process, and the final annealing temperature. On the basis of these results, a high-performance a-GIZO TFT with a field-effect mobility of 35.7 cm(2) V(-1) s(-1), a subthreshold swing of 185 mV dec(-1), a switching ratio exceeding 10(7), and a satisfactory reliability was successfully fabricated. The technology developed in this work can be realized using the existing facilities of active-matrix liquid-crystal display industries.

Role of Self-Assembled Monolayers on Improved Electrical Stability of Amorphous In-Ga-Zn-O Thin-Film Transistors

“…9 For these reasons the bias stress stability of IGZO-TFTs has been intensely investigated where effects of composition, process temperature, process conditions, gate dielectric, back channel passivation, and many other factors have been evaluated. [10][11][12][13][14][15] Proposed mechanisms for bias stress threshold voltage (V th ) shifts include electron trapping at the semiconductor/dielectric interface, electron injection into the dielectric, or formation of sub-band gap states in the bulk of films. It has also been suggested that adsorbed species (e.g., O 2 and H 2 O) on the back channel of the IGZO-TFTs can be the dominant mechanism for device instability, by providing acceptor or donor states or through field induced adsorption or desorption of these species.…”

Recent progress in high performance and reliable n-type transition metal oxide-based thin film transistors

“…Therefore, the N 2 O treated device exhibited a high mobility of 37.0 cm 2 Vs −1 , low SS of 0.25 V/ decade and low I off of 10 −13 A ( figure 12(b)). The switching property and BTS induced stability of dry etching-based BCE IGZO TFTs can be improved further by optimizing the N 2 O plasma treatment, deposition conditions and post annealing of the SiO 2 passivation layer [79].…”

24.5: Back‐Channel‐Etched a‐IGZO TFTs with TiO2:Nb Protective Layer

“…Furthermore, the overlapped regions between ESL and S-D make the channel length difficult to be less than 5 μm. Until now, several back-channel-etched (BCE) methods have been reported to fabricate a-IGZO TFT [6][7][8][9][10]. These methods can be classified into 3 categories.…”

“…These methods can be classified into 3 categories. The first one to pattern the S-D electrodes is using dry etching with post N 2 O plasma treatment [6]. Although the device performance could be recovered after post treatment on the back channel, the stability is always deteriorated.…”