Total Ionizing Dose Effects on FinFET-Based Capacitor-Less 1T-DRAMs

We have characterized the total ionizing dose (TID) response of SOI FinFETs, fabricated in two different technologies, operated in 1T-DRAM mode, one with poly-crystalline Si gates and a SiO₂ gate dielectric, and the other with metal gates and a high-K gate dielectric. These devices were programmed using both back-gate pulse and gate induced drain leakage (GIDL) programming methods. 1T-DRAM cells programmed with back-gate pulses are quite sensitive to total ionizing dose radiation, with the memory sensing margin and retention time decreasing significantly with increasing dose. In contrast, the sensing margin and retention time show high tolerance to total ionizing dose irradiation when the 1T-DRAM cells are programmed via GIDL. The sensing margin increases significantly with decreasing gate length for 1T-DRAM cells programmed via GIDL. We conclude that capacitor-less 1T-DRAMs programmed via GIDL are strong candidates for embedded memory applications for ultimately scaled CMOS devices in high-TID applications.