Total Ionization Dose Effects on Charge Storage Capability of Al_2O_3/HfO_2/Al_2O_3-Based Charge Trapping Memory Cell

Because of the discrete charge storage mechanism, charge trapping memory(CTM) technique is a good candidate for aerospace and military missions. The total ionization dose(TID) effects on CTM cells with Al_2O_3/HfO_2/Al_2O_3(AHA) high-k gate stack structure under in-situ 10 keV x-rays are studied. The C-V characteristics at different radiation doses demonstrate that charge stored in the device continues to be leaked away during the irradiation,thereby inducing the shift of flat band voltage(V_(fb)). The dc memory window shows insignificant changes, suggesting the existence of good P/E ability. Furthermore, the physical mechanisms of TID induced radiation damages in AHA-based CTM are analyzed.     

Total Ionizing Dose Effects of 55-nm Silicon-Oxide-Nitride-Oxide-Silicon Charge Trapping Memory in Pulse and DC Modes

The ~(60)Co-γ ray total ionizing dose radiation responses of 55-nm silicon-oxide-nitride-oxide-silicon(SONOS) memory cells in pulse mode(programmed/erased with pulse voltage) and dc mode(programmed/erased with direct voltage sweeping) are investigated. The threshold voltage and off-state current of memory cells before and after radiation are measured. The experimental results show that the memory cells in pulse mode have a better radiation-hard capability. The normalized memory window still remains at 60% for cells in dc mode and 76% for cells in pulse mode after 300 krad(Si) radiation. The charge loss process physical mechanisms of programmed SONOS devices during radiation are analyzed.