In the post-Moore era, oxide thin-film transistors (TFTs), particularly wide-bandgap semiconductor transistors represented by amorphous indium gallium zinc oxide (a-IGZO), have attracted significant attention due to their low-temperature fabrication process, excellent compatibility with back-end-of-line (BEOL) processes, and outstanding electrical performance. These devices have been widely applied in fields such as displays, monolithic three-dimensional (3D) integration, and memory technologies. This article focuses on the dimensional scaling technology of a-IGZO TFTs, especially two key dimensions—channel length (L_ch) and contact length (LC)—to enhance density and performance. For channel scaling, architectural innovations such as dual-gate structures have been instrumental in mitigating short-channel effects, enabling devices with L_ch scaled down to 30 nm to achieve a near-ideal subthreshold swing of 63.4 mV/decade and a high transconductance of 559 μS/μm. Concurrently, vertical transistor designs, like channel-all-around architectures, have successfully pushed L_ch to 50 nm while maintaining excellent gate control and leakage currents below 10^-17 A/μm. Regarding contact scaling, interface engineering and optimized deposition processes have reduced the contact length to 20-40 nm, achieving a minimal contact pitch of 80 nm and a low specific contact resistivity. These developments highlight the strong potential of scaled a-IGZO TFTs. This article also summarizes and prospects their application potential in monolithic 3D integration and high-density memory fields.