The effects of an N 2 O anneal on the radiation effects of a split-gate electrical erasable programmable read only memory (EEPROM)/flash cell with a recently-proposed hornshaped floating gate were studied. We have found that although the cells appear to survive 1 Mrad(Si) Co 60 irradiation without data retention failure, the write/erase cycling endurance was severely impeded after irradiation. Specifically, the write/erase cycling endurance was degraded to 20 K from the pre-irradiation value of

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... 50 K. However, by adding an N2O annealing step after the interpoly oxidation, the after-irradiation write/erase cycling endurance of the resultant cell can be significantly improved to over 45 K. N2O annealing also improves the after-irradiation program and erase efficiencies. The N2O annealing step therefore presents a potential method for enhancing the robustness of the horn-shaped floating-gate EEPROM/flash cells for radiation-hard applications. Index Terms-EEPROM/flash cells, horn-shaped floating-gate, N2O annealing, and radiation hardness.