Effect of IGZO thin films fabricated by Pulsed-DC and RF sputtering on TFT characteristics

Abstract

Various studies have been conducted to improve TFT's processing methods and characteristics. In this study, we conducted an experiment to produce a high-performance amorphous indium–gallium–zinc oxide (a-IGZO) TFT using the sputtering method, which has attracted attention as an a-IGZO channel layer deposition method. The characteristics of a-IGZO thin films deposited by pulsed-DC magnetron sputtering and RF magnetron sputtering were analyzed. Furthermore, the effect of the characteristics of thin films on the electrical characteristics of TFT devices according to the sputtering method was investigated. For thin film analysis, a-IGZO samples were prepared and analyzed on eagle glass with the same thickness of 30 nm by the sputtering methods and then applied to the TFT devices to analyze their characteristics. Chemical analysis using XPS showed that pulsed-DC sputtering had a higher deposition rate, oxygen binding rate, oxygen vacancy ratio, bandgap and good uniformity than RF sputtering. Subsequently, the density of the thin film was analyzed using XRR. When applied to TFT devices, the threshold voltages of 1.65V, 1.34V, and saturation mobility of 13.06 V/cm2, 18.20 V/cm2, S.S. of 0.50 V/Dec, 0.34 V/Dec, On/Off ratio of 2.62 × 107, 4.73 × 107 were showed to the devices fabricated by RF and pulsed-DC, respectively. The stability of the bias and illumination was investigated, and the characteristics of the TFT devices fabricated through pulsed-DC were confirmed to be more excellent. These results can be helpful for future research regarding replacement of a-Si and poly-Si TFTs in the fabrication of semiconductor devices for next generation display.