| 초록 |
Amorphous oxide semiconductors (AOS) have become one of superb active materials of thin-film transistor (TFT) backplane for active matrix displays due to their excellent characteristics such as a high field-effect mobility, low off-current, and low subthreshold slope. Recently, it has been much attention to secure high performance TFT characteristics at low temperature process for flexible and stretchable display application. It is important to fabricate TFTs at the temperature below 150 ˚C to minimize dimensional changes on plastic substrates during TFT processes. In this paper, the electrical properties of In-Ga-Sn-O (IGTO) thin-films such as carrier concentrations (Ne), and Hall mobilities (μH) were examined with different annealing temperatures to ascertain feasibility as a semiconductor with high mobility at low process temperature. The IGTO thin-films were sputter deposited, and annealed from 150 to 350 ˚C at intervals of 50 ˚C, respectively. Hall measurements of the films were carried out using the van der Pauw configuration. We also fabricated IGTO TFTs with top gate staggered structure. The IGTO thin-films were deposited with the change of various sputtering parameters such as thickness and oxygen (O2)/argon (Ar) partial pressure to improve the performance of the IGTO TFTs. at r.t. Aluminum oxide (Al2O3) as a gate insulator was deposited using atomic layer deposition (ALD). We investigated the electrical characteristics of the IGTO TFTs fabricated under various ALD process conditions, which largely affect a formation of channel interface of the TFTs. As optimizing the process conditions of the IGTO and the Al2O3 thin-films with low temperatures on polyimide substrates, we could obtain excellent electrical characteristics with high field-effect mobility above 30 cm2V-1s-1 and low subthreshold shop of 0.18 Vdec-1 with moderate electrical reliability. It demonstrates that the IGTO can be a promising low-temperature-processable semiconductor for TFT backplane of flexible and stretchable displays. |
