An Oxide-Buffered BE-MANOS Charge-Trapping Device and the Role of Al{sub}2O{sub}3

摘要

The role of Al{sub}2O{sub}3 in MANOS device is critically examined, and we conclude that its primary function is to reduce gate injection during erase operation. By itself, Al{sub}2O{sub}3 cannot stop charge leakage from the charge-trapping nitride layer. Furthermore, Al{sub}2O{sub}3 provides no magic during the erase operation, and MANOS erases very slowly through charge de-trapping. BE-SONOS [1], with the band engineered ONO tunneling layers, provides efficient channel hole injection for erase. BE-MANOS [2] should be an ideal combination with fast erase and good reliability. However, it shows poor data retention. By inserting a SiO{sub}2 buffer layer between Al{sub}2O{sub}3 and the SiN storage layer, the oxide-buffered BE-MANOS shows good performance and good reliability. The EOT scalability is also investigated.