연구홍보포털

논문 초록 (Abstract)

Trench-structured thin-film transistors (TFTs) based on oxide semiconductors have attracted increasing attention for next-generation high-resolution displays, owing to their compact footprint and potential for high current-driving capability in short-channel configurations. However, prior approaches to increasing the current in trench-structured oxide TFTs often rely on non-uniform thicknesses induced by sputtering, which are difficult to control and reproduce. This paper presents a trench TFT with an oxide semiconductor active layer deposited via atomic layer deposition (ALD) combined with selective protective layer (PL) dry etching. The optimized device with a short channel length of 5.51 µm achieves an ultra-high normalized on-current of 163.2 µA/µm and on/off ratio exceeding 1010 at a drain voltage of 4.1 V. Directional dry etching selectively removes the PL from the horizontal device regions, significantly altering their electrical properties while preserving the integrity of the vertical channel. This enables region-specific electrical tuning that overcomes the uncontrolled characteristics of conventional trench TFTs formed by non-uniform deposition. Multiple characterization techniques confirmed that BCl₃ dry etching introduces shallow donor-like states near the etched surface, effectively increasing the free-carrier concentration in the horizontal channel regions. This localized doping lowers the channel resistance, and thereby contributes to a significant improvement in the overall electrical performance. The optimized ALD-based trench TFT exhibits a favorable subthreshold swing (0.108 V/dec) and acceptable turn-on voltage (−0.68 V). These results demonstrate that the ALD trench TFT with selective dry etching provides a promising strategy for future high-performance ultra-high-resolution display backplanes