In-situ Ar plasma treatment as a low thermal budget technique for high performance InGaSnO thin film transistors fabricated using magnetron sputtering

Abstract

High-performance InGaSnO thin film transistors are successfully fabricated with a reduced thermal budget by an in-situ Ar plasma treatment process. This process does not require external equipment for plasma treatment of the deposited film, which ensures the original vacuum environment and uses plasma energy for weak treatment. The atomic force microscope measurement shows that the surface roughness of the InGaSnO thin film decreased from 0.472 nm to 0.266 nm after treatment. The reduction of oxygen vacancy defect states is verified by the O 1s spectrum of X-ray photoelectron spectroscopy, and its interfacial defect density is also significantly reduced. The stabilities of InGaSnO TFTs are also considerably improved, with the threshold voltage shift under the negative bias stress test reduced to 0.39 V, better than annealing at 300 °C. Ar plasma treatment improves film quality and enhances device performance, which exhibits high field-effect mobility (30.8 cm2/Vs), a small sub-threshold swing (0.32 V/decade), and a low threshold voltage (−0.54 V). Overall, in-situ Ar plasma treatment not only reduces the thermal budget but also simplifies the process, enabling the utility of long-term high-temperature annealing, showing its potential in flexible display applications.