Performance improvement of SONOS memory by bandgap engineering of charge-trapping layer |
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Authors: | Tung-Sheng Chen Kuo-Hong Wu Hsien Chung Chin-Hsing Kao |
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Affiliation: | Dept. of Electr. Eng., Nat. Defense Univ., Taoyuan, Taiwan; |
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Abstract: | A significant improvement in device performance and reliability characteristics of silicon-oxide-nitride-oxide-silicon (SONOS) Flash memory has been achieved. Superior endurance characteristic shows no sign of degradation even after 10/sup 6/ program/erase cycles and an extrapolated ten-year detection window of 1.4 V has been attained from retention measurement. The dramatic improvement results from a bandgap engineering of the SiN charge-trapping layer. With a gradual variation of the Si/N ratio from bottom to top of nitride film rather than uniform standard composition, a large number of highly accessible trapping levels are created in addition to the deepened barrier height between nitride and tunnel oxide that reduces back-tunneling probability. The proposed technique shall be valuable in pushing Flash memory technology into the next generation. |
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