Total-Ionizing-Dose Effects on Polycrystalline-Si Channel Vertical-Charge-Trapping Nand Devices

Total-ionizing-dose effects are evaluated in vertical-charge-trapping NAND devices with silicon oxynitride (SiON) and SiO2 tunneling layers. Processing splits include SiON tunneling layers with and without H ₂ /D ₂ high-pressure annealing. Programmed devices were irradiated to 500 krad(SiO ₂ ) with 10-keV X-rays and annealed for 30 min. Second programming after annealing does not fully restore the original, programmed state. Radiation-induced trapped holes compensate for deeply trapped electrons that are injected into the dielectric during device programming. Throughout the full irradiation and annealing sequence, threshold voltages remain large enough to enable successful nonvolatile (NV) memory application.