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

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, SiO x 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 SiO x 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 cm2 V–1 s–1, a subthreshold swing of 185 mV dec–1, a switching ratio exceeding 107, 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.