09-07-2011, 03:59 PM
INTEREST in nitride-based localized trapping storage Flash memory cells has revived for 10-min-cell operation, which can double the memory density. Besides, they also show better scalability since charges are stored in nitride traps rather than a poly silicon floating-gate in conventional Flash memory cells. Nitride storage memories do not have floating-gate-induced drain turn-on and coupling issues, which are believed to be the scaling limitations of conventional floating-gate memories .Various operation schemes were proposed based on the nitride-storage cell structure. A novel PHINES cell is proposed based on the nitride storage cell structure
Recently, NROM cell with channel-hot-electron (CHE) programming and band-to-band tunneling induced hot hole (BTBT HH) erasing has demonstrated excellent intrinsic cell Performance. In spite of many advantages, previous works reveal that reliability issues including read disturb, over erase and cell retention after cycling are major challenges of a NROM cell. Swift et al .proposed to use uniform tunneling for erasing instead of the HH injection to reduce stress induced degradation in erase. However, for mass data storage, CHE programming is still not suitable due to its high power consumption.
