3D-Stacked CAAC-In-Ga-Zn Oxide FETs with Gate Length of 72nm

We have fabricated two monolithic 3D-stacked c- axis aligned crystalline In-Ga-Zn oxide FETs (CAAC-IGZO FETs) with a gate length of 72nm using CAAC-IGZO as the channel material. Estimated off-state leakage current at 85°C, estimated write time for dynamic oxide semiconductor RAM at −40°C, estimated write time for nonvolatile oxide semiconductor RAM at −40°C, and estimated endurance at 27°C of the fabricated CAAC-IGZO FETs are less than 5.0 × 10−20 A/μm, 1.0 to 3.0 ns, 1.0 to 10.0 ns, and more than 1012 times, respectively. A memory cell using the CAAC-IGZO FETs has extremely long-term data retention (nonvolatile), high-speed operation (high-speed read/write and erase operations) and high endurance. These features cannot be achieved with Si FETs.