• Realization of 1 µm short-channel SATG ITZO TFTs with Al 2 O 3 /SiO 2 stacked GI. • Outstanding electrical performance with suppressed short-channel effects. • Al 2 O 3 /SiO 2 GI passivates interface defects and enhances GI bonding network integrity. • Defect passivation mechanism elucidated via ToF-SIMS and XPS analyses. • Findings guide scaling of SATG oxide TFTs for future semiconductor engineering. Virtual and augmented reality and other next-generation displays require ultrahigh-resolution. This trend, in turn, drives aggressive pixel scaling, necessitating the miniaturization of thin-film transistors (TFTs) that control each pixel. High-performance TFTs that operate reliably in the short-channel regime are therefore essential. Herein, 1-µm short-channel self-aligned top-gate (SATG) In–Sn–Zn–O (ITZO) TFTs incorporating an Al 2 O 3 /SiO 2 dual-layer gate insulator (GI) are realized. The devices are compatible with low-temperature processing and exhibit excellent electrical characteristics: a field-effect mobility of 38.76 cm 2 /Vs, a subthreshold swing of 0.08 V/decade, a threshold voltage of −1.28 V, an on/off current ratio of ∼10 8 , a negligible drain-induced barrier lowering of ≈0 mV/V, and a threshold voltage shift of +0.23 V under negative bias stress. To elucidate the origin of the remarkable performance in these micron-scale Al 2 O 3 /SiO 2 GI devices, the fundamental dielectric properties of the GI were evaluated, and time-of-flight secondary ion mass spectrometry (ToF-SIMS) depth profiling and X-ray photoelectron spectroscopy (XPS) analysis were conducted. The results reveal that in addition to the enhanced insulating properties of the GI, the outstanding performance of the Al 2 O 3 /SiO 2 GI devices is attributable to the dielectric stack, which effectively passivates dangling bond–related defects at the GI–channel interface and strengthens the bonding network and structural integrity of the underlying SiO 2 bulk. Consequently, the high-performance 1-µm-channel SATG ITZO TFTs and the underlying mechanisms identified in this study represent substantial advancements, with implications that extend to the broader field of advanced semiconductors.
Shin et al. (Sat,) studied this question.