A Highly Reliable Multi-level and 2-bit/cell Operation of Wrapped-Select-Gate (WSG) SONOS Memory with Optimized ONO Thickness

High-performance wrapped-select-gate (WSG) SONOS (silicon-oxide-nitride-silicon) memory cells with multi-level and 2-bit/cell operation have been successfully demonstrated. The source-side injection mechanism with different ONO thickness in WSG-SONOS memory was well investigated. The different programming efficiency of the WSG-SONOS memory with different ONO thickness can be explained by the lateral electrical field extracted from the simulation. Furthermore, multi-level storage is easily obtained and well V
_th
distribution is also presented. High program/erase speed (10 us/5 ms) and low programming current (3.5 u/A) are performed to achieve the multi-level operation with excellent gate and drain disturbance, second-bit effect, data retention and endurance.