Title :
Improving radiation hardness of EEPROM/flash cell by N2O annealing
Author :
Huang, Tiao-Yuan ; Jong, Fuh-Cheng ; Chao, Tien-Sheng ; Lin, Horng-Chih ; Leu, Len-Yi ; Young, Konrad ; Lin, Chen-Hsi ; Chin, K.Y.
Author_Institution :
Dept. of Electron. Eng., Nat. Chiao Tung Univ., Hsinchu, Taiwan
fDate :
7/1/1998 12:00:00 AM
Abstract :
The effects of an N/sub 2/O anneal on the radiation effects of a split-gate electrical erasable programmable read only memory (EEPROM)/flash cell with a recently-proposed horn-shaped floating gate were studied. We have found that although the cells appear to survive 1 Mrad(Si) Co/sup 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 50 K. However, by adding an N/sub 2/O 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. N/sub 2/O annealing also improves the after-irradiation program and erase efficiencies. The N/sub 2/O annealing step therefore presents a potential method for enhancing the robustness of the horn-shaped floating-gate EEPROM/flash cells for radiation-hard applications.
Keywords :
CMOS memory circuits; EPROM; annealing; gamma-ray effects; integrated circuit testing; nitridation; oxidation; radiation hardening (electronics); 1 Mrad; 20 to 50 K; CMOS; Co/sup 60/ irradiation; EEPROM/flash cell; N/sub 2/O; N/sub 2/O anneal; N/sub 2/O annealing; after-irradiation program efficiencies; after-irradiation write/erase cycling endurance; data retention failure; erase efficiencies; horn-shaped floating gate; horn-shaped floating-gate EEPROM/flash cells; interpoly oxidation; radiation hardness; radiation-hard applications; split-gate electrical erasable programmable read only memory; write/erase cycling endurance; Annealing; Chaos; Degradation; EPROM; Laboratories; Nonvolatile memory; Pulse amplifiers; Radiation effects; Space technology; Split gate flash memory cells;
Journal_Title :
Electron Device Letters, IEEE
